JP2024158076A - Excavator - Google Patents

Abstract

To provide a shovel that can improve work efficiency.
[Solution] The excavator 100 includes a lower traveling body 1, an upper rotating body 3 rotatably mounted on the lower traveling body 1, an attachment AT including a boom 4, an arm 5, and a bucket 6 attached to the upper rotating body 3, and a controller 30 that repeatedly calculates an excavation force based on information related to an excavation operation by the attachment AT. In order to prevent the lower traveling body 1 from rotating about a fulcrum due to a reaction force of the excavation force generated during an arm closing operation, causing the front end of the upper rotating body 3 to lift up, the controller 30 raises the boom 4 so that the tip of the bucket 6 moves toward the fulcrum when the excavation force exceeds a predetermined value.
[Selected Figure] Figure 1

Description

This disclosure relates to a shovel.

Shovels equipped with an overload prevention device are known in the art (see Patent Document 1).

Japanese Patent Application Publication No. 64-6420

The above-mentioned overload prevention device detects the hydraulic oil pressure in the bottom oil chamber of the boom cylinder as a reaction force from the ground while the shovel is excavating, and when that pressure reaches a predetermined pressure, it automatically activates the attachment, preventing the front end of the shovel from lifting up.

However, the above-mentioned overload prevention device automatically operates the attachment as long as the pressure of the hydraulic oil in the bottom oil chamber of the boom cylinder reaches a predetermined pressure. Therefore, the above-mentioned overload prevention device does not allow the excavator to perform excavation that makes maximum use of its own weight, and there is a risk of reducing work efficiency.

Therefore, it is desirable to provide a shovel that can improve work efficiency.

The excavator according to an embodiment of the present disclosure includes a lower running body, an upper rotating body rotatably mounted on the lower running body, an attachment including a boom, an arm, and a bucket attached to the upper rotating body, and a control device that repeatedly calculates an excavation force based on information related to an excavation operation performed by the attachment. When the excavation force exceeds a predetermined value, the control device raises the boom so that the tip of the bucket moves toward the fulcrum in order to prevent the lower running body from rotating about a fulcrum due to a reaction force of the excavation force generated during an arm closing operation, causing the front end of the upper rotating body to lift up.

The above-mentioned shovel can improve work efficiency.

FIG. FIG. 2 is a diagram illustrating an example of the configuration of a control system for a shovel. FIG. 1 is a diagram illustrating a schematic configuration example of a hydraulic system of a shovel. FIG. 1 is a diagram of a portion of the hydraulic system for operation of the arm cylinder. FIG. 2 is a diagram of a portion of the hydraulic system involved in the operation of the boom cylinder. FIG. 2 is a diagram of a portion of a hydraulic system for operation of a bucket cylinder. FIG. 2 is a diagram of a portion of a hydraulic system relating to the operation of a swing hydraulic motor. FIG. 1 is a diagram of a portion of the hydraulic system relating to the operation of the left traveling hydraulic motor. FIG. 1 is a diagram of a portion of the hydraulic system relating to the operation of the right travel hydraulic motor. FIG. 1 is a diagram showing the relationship of forces acting on a shovel when excavation is performed. 13 is a flowchart showing an example of the flow of a support process. FIG. 13 is a diagram showing a state in which an excavator executing a support process excavates a pile of earth and sand.

The shovel 100 according to an embodiment of the present disclosure will now be described with reference to the drawings. First, an overview of the shovel 100 will be described with reference to FIG. 1. FIG. 1 is a side view of the shovel 100.

The excavator 100 includes a lower carrier 1, an upper rotating body 3 mounted on the lower carrier 1 so as to be freely rotatable via a rotating mechanism 2, a boom 4, an arm 5, and a bucket 6 constituting an excavation attachment which is an example of an attachment AT, and a cabin 10.

The lower traveling body 1 allows the excavator 100 to travel by hydraulically driving a pair of left and right crawlers by traveling hydraulic motors 2M (see FIG. 2). The traveling hydraulic motors 2M include a left traveling hydraulic motor 2ML and a right traveling hydraulic motor 2MR. In other words, the left traveling hydraulic motor 2ML and the right traveling hydraulic motor 2MR drive the lower traveling body 1 (crawlers) as the driven part.

The upper rotating body 3 is driven by a hydraulic motor 2A (see FIG. 2) to rotate relative to the lower traveling body 1. In other words, the hydraulic motor 2A is a rotation drive unit that drives the upper rotating body 3 as a driven unit, and can change the orientation of the upper rotating body 3.

The upper rotating body 3 may be electrically driven by a rotating electric motor as an electric actuator instead of the rotating hydraulic motor 2A. In other words, the rotating electric motor is a rotating drive part that drives the upper rotating body 3 as a driven part, similar to the rotating hydraulic motor 2A, and can change the orientation of the upper rotating body 3.

The boom 4 is rotatably attached to the center of the front of the upper rotating body 3, an arm 5 is rotatably attached to the tip of the boom 4, and a bucket 6 is rotatably attached to the tip of the arm 5 as an end attachment. The boom 4, arm 5, and bucket 6 are hydraulically driven by a boom cylinder 7, arm cylinder 8, and bucket cylinder 9, which serve as hydraulic actuators, respectively.

The bucket 6 is an example of an end attachment, and other end attachments, such as a slope bucket, a dredging bucket, or a breaker, may be attached to the tip of the arm 5 instead of the bucket 6 depending on the work content, etc.

The cabin 10 is the driver's compartment in which the operator sits and is located on the front left side of the upper rotating body 3.

Next, the specific configuration of the shovel 100 will be described with reference to FIG. 2 in addition to FIG. 1. FIG. 2 is a diagram that shows a schematic example of the configuration of the control system of the shovel 100. In FIG. 2, the mechanical power transmission lines, hydraulic oil lines, pilot lines, and electrical signal lines are indicated by double lines, solid lines, dashed lines, and dotted lines, respectively.

The drive system of the excavator 100 includes an engine 11, a regulator 13, a main pump 14, and a control valve unit 17. The hydraulic drive system of the excavator 100 also includes hydraulic actuators such as a travel hydraulic motor 2M, a swing hydraulic motor 2A, a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9 that hydraulically drive the lower travel structure 1, the upper swing structure 3, the boom 4, the arm 5, and the bucket 6, respectively.

The engine 11 is a power source in the hydraulic drive system, and is mounted, for example, at the rear of the upper rotating body 3. Specifically, the engine 11 rotates at a constant speed at a preset target speed under direct or indirect control by the controller 30, and drives the main pump 14 and the pilot pump 15. The engine 11 is, for example, a diesel engine.

The regulator 13 controls the discharge volume of the main pump 14. For example, the regulator 13 adjusts the angle (tilt angle) of the swash plate of the main pump 14 in response to a control command from the controller 30. The regulator 13 includes, for example, a left regulator 13L and a right regulator 13R (see FIG. 3).

The main pump 14 is mounted, for example, on the rear of the upper rotating body 3, and supplies hydraulic oil to the control valve unit 17 through a hydraulic oil line. The main pump 14 is driven by the engine 11. The main pump 14 is, for example, a variable displacement hydraulic pump, and under the control of the controller 30, the tilt angle of the swash plate is adjusted by the regulator 13 to adjust the stroke length of the piston, thereby controlling the discharge flow rate (displacement volume). The main pump 14 includes, for example, a left main pump 14L and a right main pump 14R (see FIG. 3).

The control valve unit 17 is a hydraulic control device mounted, for example, at the center of the upper rotating body 3, and controls the hydraulic drive system in response to the operation of the operating device 26 by the operator. The control valve unit 17 is connected to the main pump 14 via a hydraulic oil line, and selectively supplies hydraulic oil supplied from the main pump 14 to each of a plurality of hydraulic actuators (travel hydraulic motor 2M, swing hydraulic motor 2A, boom cylinder 7, arm cylinder 8, and bucket cylinder 9) in response to the operating state of the operating device 26. Specifically, the control valve unit 17 includes control valves 171 to 176 that control the flow rate and flow direction of hydraulic oil supplied from the main pump 14 to each of the hydraulic actuators. More specifically, the control valve 171 corresponds to the left traveling hydraulic motor 2ML, the control valve 172 corresponds to the right traveling hydraulic motor 2MR, and the control valve 173 corresponds to the swing hydraulic motor 2A. Furthermore, control valve 174 corresponds to bucket cylinder 9, control valve 175 corresponds to boom cylinder 7, and control valve 176 corresponds to arm cylinder 8. Control valve 175 includes, for example, control valve 175L and control valve 175R, and control valve 176 includes, for example, control valves 176L and 176R (see FIG. 3).

The operation system of the shovel 100 includes a pilot pump 15 and an operating device 26. The operation system of the shovel 100 also includes a solenoid valve 31 as a component related to the machine control function by the controller 30.

The pilot pump 15 is mounted, for example, at the rear of the upper rotating body 3 and supplies pilot pressure to each pilot port of the control valves 171 to 176 via a pilot line. The pilot pump 15 is, for example, a fixed displacement hydraulic pump, and is driven by the engine 11.

The operating device 26 is provided near the driver's seat in the cabin 10, and is an operation input means for the operator to operate various operating elements (lower traveling body 1, upper rotating body 3, boom 4, arm 5, bucket 6, etc.). In other words, the operating device 26 is an operation input means for the operator to operate the hydraulic actuators (travel hydraulic motor 2M, swing hydraulic motor 2A, boom cylinder 7, arm cylinder 8, bucket cylinder 9, etc.) that drive each operating element. A pilot pressure according to the operation content (operation direction and operation amount) of the operating device 26 is input to each pilot port of the control valves 171 to 176. In the illustrated example, the operation device 26 includes a left operation lever 26L (see FIG. 4A) which is a lever device for operating the upper rotating body 3 (swing hydraulic motor 2A) and the arm 5 (arm cylinder 8), a right operation lever 26R (see FIG. 4B) which is a lever device for operating the boom 4 (boom cylinder 7) and the bucket 6 (bucket cylinder 9), and a travel operation device 26D (see FIG. 4E) which operates the crawler (travel hydraulic motor 2M) of the lower traveling body 1. The travel operation device 26D includes a left travel lever 26DL (see FIG. 4E) which operates the left crawler (left traveling hydraulic motor 2ML) and a right travel lever 26DR (see FIG. 4F) which operates the right crawler (right traveling hydraulic motor 2MR). The travel operation device 26D may include a left travel pedal which operates the left crawler (left traveling hydraulic motor 2ML) and a right travel pedal which operates the right crawler (right traveling hydraulic motor 2MR).

In the illustrated example, the operating device 26 is an electric type that outputs an electric signal, and the electric signal from the operating device 26 is input to the controller 30, which controls the pilot pressure acting on each pilot port of the control valves 171 to 176 according to the input electric signal, thereby realizing the operation of various hydraulic actuators according to the operation content of the operating device 26. Specifically, between the pilot pump 15 and each pilot port of the control valves 171 to 176, a solenoid valve 31 that operates according to an electric signal from the controller 30 is disposed. Then, when the operating device 26 is operated, the controller 30 controls the solenoid valve 31 by an electric signal corresponding to the operation amount (e.g., the lever operation amount) to increase or decrease the pilot pressure, thereby operating each of the control valves 171 to 176 according to the operation content of the operating device 26. The control valves 171 to 176 may be electromagnetic solenoid spool valves that are driven by commands from the controller 30.

The control system of the excavator 100 includes a controller 30, a discharge pressure sensor 28, an operation sensor 29, a solenoid valve 31, a display device 40, an input device 42, a sound output device 43, a memory device 47, a boom angle sensor S1, an arm angle sensor S2, a bucket angle sensor S3, a machine body inclination sensor S4, a turning state sensor S5, an imaging device S6, a positioning device Q1, and a communication device T1.

The controller 30 (an example of a control device) is provided in the cabin 10 and is configured to control the drive of the excavator 100. The functions of the controller 30 may be realized by any hardware, software, or a combination thereof. In the illustrated example, the controller 30 is configured mainly with a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a non-volatile auxiliary storage device, various input/output interfaces, etc. The controller 30 realizes various functions by, for example, executing various programs stored in the ROM or non-volatile auxiliary storage device on the CPU.

In the illustrated example, the controller 30 sets a target rotation speed based on a work mode, etc., that is preset by a predetermined operation by an operator, etc., and performs drive control to rotate the engine 11 at a constant speed. The controller 30 may output a control command to the regulator 13 as necessary to change the discharge volume of the main pump 14.

The controller 30 may be configured to control a machine guidance function that guides the operator in manually operating the shovel 100 through the operating device 26. The controller 30 may also be configured to control a machine control function that automatically assists the operator in manually operating the shovel 100 through the operating device 26. In this case, the controller 30 may include a machine guidance unit 50 as a functional unit related to the machine guidance function and the machine control function.

In addition, some of the functions of the controller 30 may be realized by other controllers (control devices). That is, the functions of the controller 30 may be realized in a distributed manner by multiple controllers. For example, the machine guidance function and the machine control function may be realized by a dedicated controller (control device).

The discharge pressure sensor 28 detects the discharge pressure of the main pump 14. A detection signal corresponding to the discharge pressure detected by the discharge pressure sensor 28 is input to the controller 30. The discharge pressure sensor 28 includes, for example, a left discharge pressure sensor 28L and a right discharge pressure sensor 28R (see FIG. 3).

The operation sensor 29 detects the operation contents (operation direction and operation amount) of the operation device 26. The detection signal of the operation sensor 29 is taken into the controller 30. The operation sensor 29 includes, for example, an operation sensor 29LA (see FIG. 4A) that detects the operation contents in the front-rear direction (arm operation direction) of the left operation lever 26L, an operation sensor 29RA (see FIG. 4B) that detects the operation contents in the front-rear direction (boom operation direction) of the right operation lever 26R, an operation sensor 29RB (see FIG. 4C) that detects the operation contents in the left-right direction (bucket operation direction) of the right operation lever 26R, an operation sensor 29LB (see FIG. 4D) that detects the operation contents in the left-right direction (swing operation direction) of the left operation lever 26L, an operation sensor 29DL (see FIG. 4E) that detects the operation contents of the left travel lever 26DL, and an operation sensor 29DR (see FIG. 4F) that detects the operation contents of the right travel lever 26DR.

In the illustrated example, the operation sensor 29 is a tilt sensor capable of detecting the amount of operation (amount of tilt) and the direction of tilt of the operating device 26, but it may be any sensor such as an encoder or potentiometer.

The solenoid valve 31 is provided in a pilot line connecting the pilot pump 15 and each pilot port of the control valves 171 to 176, and is configured so that its flow path area (cross-sectional area through which hydraulic oil can flow) can be changed. The solenoid valve 31 operates in response to a control command input from the controller 30. This allows the controller 30 to supply pilot oil discharged from the pilot pump 15 to each pilot port of the control valves 171 to 176 via the solenoid valve 31, even when the operating device 26 is not being operated by the operator. In the illustrated example, the solenoid valve 31 includes solenoid valves 31AL to 31FL and solenoid valves 31AR to 31FR, as shown in Figures 4A to 4F.

The display device 40 is provided in a location that is easily visible to an operator seated in the driver's seat inside the cabin 10, and displays various information under the control of the controller 30. The display device 40 may be connected to the controller 30 via an in-vehicle communication network, or may be connected to the controller 30 via a one-to-one dedicated line.

The input device 42 is provided within reach of an operator seated in the driver's seat inside the cabin 10, accepts various operational inputs by the operator, and outputs signals corresponding to the operational inputs to the controller 30. The input device 42 is, for example, a touch panel mounted on the screen of the display device 40 that displays various information, a knob switch provided at the tip of the lever of a lever device, a button switch, lever, toggle switch, or rotary dial installed around the display device 40, etc. Signals corresponding to operations on the input device 42 are taken into the controller 30.

The input device 42 also has a mode switch 42a. The mode switch 42a is a switch for switching the work mode of the shovel 100. The work mode refers to the type of work performed by the shovel 100, and includes, for example, a crane mode and a normal mode. The mode switch 42a may be a software switch displayed on the screen of the display device 40, a hardware switch installed in the vicinity of the display device 40, or a switch installed in another position within the cabin 10.

The sound output device 43 is provided, for example, in the cabin 10, connected to the controller 30, and outputs sound under the control of the controller 30. The sound output device 43 is, for example, a speaker or a buzzer. The sound output device 43 audibly outputs various information in response to a sound output command from the controller 30.

The storage device 47 is provided, for example, in the cabin 10, and stores various information under the control of the controller 30. The storage device 47 is, for example, a non-volatile storage medium such as a semiconductor memory. The storage device 47 may store information output by various devices during operation of the shovel 100, or may store information acquired via various devices before operation of the shovel 100 is started. The storage device 47 may store data regarding a target point acquired, for example, via the communication device T1, or set via the input device 42, for example. The target point is, for example, a point on a target construction surface. The data regarding the target point may be set (saved) by the operator of the shovel 100, or may be set by a construction manager, etc.

The boom angle sensor S1 is attached to the boom 4 and detects the rotation angle of the boom 4 (hereinafter, "boom angle"). The boom angle is, for example, the angle formed by a straight line connecting both ends of the boom 4 (center points of the connecting pins) with the rotation plane (plane perpendicular to the rotation axis) of the upper rotating body 3 in a side view. The boom angle sensor S1 is, for example, a rotary encoder, an acceleration sensor, a six-axis sensor, an IMU (Inertial Measurement Unit), or a combination thereof. The boom angle sensor S1 may also be composed of a potentiometer using a variable resistor, a stroke sensor that detects the stroke amount of a hydraulic cylinder (boom cylinder 7) corresponding to the boom angle, or the like. The same applies to the arm angle sensor S2 and the bucket angle sensor S3. The detection signal corresponding to the boom angle by the boom angle sensor S1 is taken into the controller 30.

The arm angle sensor S2 is attached to the arm 5 and detects the rotation angle of the arm 5 (hereinafter, the "arm angle"). For example, in a side view, the arm angle is the angle between a line connecting both ends of the boom 4 (the center points of the connecting pin) and a line connecting both ends of the arm 5 (the center points of the connecting pin). A detection signal corresponding to the arm angle by the arm angle sensor S2 is input to the controller 30.

The bucket angle sensor S3 is attached to the bucket 6 and detects the rotation angle of the bucket 6 (hereinafter, "bucket angle"). For example, in a side view, the bucket angle is the angle between a line connecting both ends of the arm 5 (center points of the connecting pin) and a line connecting the fulcrum (center point of the connecting pin) and the tip (blade tip) of the bucket 6. A detection signal corresponding to the bucket angle by the bucket angle sensor S3 is input to the controller 30. Note that the bucket angle sensor S3 may be omitted.

The machine body tilt sensor S4 detects the tilt state of the machine body (upper rotating body 3 or lower running body 1) relative to the horizontal plane. The machine body tilt sensor S4 is attached to, for example, the upper rotating body 3, and detects the tilt angles around two axes in the forward/backward and left/right directions (hereinafter, "forward/rearward tilt angle" and "left/right tilt angle") of the shovel 100 (i.e., upper rotating body 3). The machine body tilt sensor S4 is, for example, a rotary encoder, an acceleration sensor, a six-axis sensor, an IMU, or a combination thereof. The detection signal corresponding to the tilt angle (forward/backward tilt angle and left/right tilt angle) by the machine body tilt sensor S4 is input to the controller 30.

The rotation state sensor S5 outputs information regarding the rotation state of the upper rotating body 3. The rotation state sensor S5 detects, for example, the rotation angular velocity of the upper rotating body 3. The rotation state sensor S5 may also detect the rotation angle. The rotation state sensor S5 is, for example, a gyro sensor, a resolver, or a rotary encoder. The detection signal corresponding to the rotation angular velocity of the upper rotating body 3 by the rotation state sensor S5 is input to the controller 30.

The imaging device S6, which serves as a spatial recognition device, captures images of the periphery of the shovel 100. In the illustrated example, the imaging device S6 includes a camera S6F that captures an image in front of the shovel 100, a camera S6L that captures an image to the left of the shovel 100, a camera S6R that captures an image to the right of the shovel 100, and a camera S6B that captures an image to the rear of the shovel 100. The imaging device S6 may be directly connected to the controller 30 so as to be able to communicate with it.

In the illustrated example, camera S6F is attached to the ceiling of cabin 10, i.e., inside cabin 10. Camera S6F may also be attached to the outside of cabin 10, such as the roof of cabin 10 or the side of boom 4. Camera S6L is attached to the left end of the top surface of upper rotating body 3, camera S6R is attached to the right end of the top surface of upper rotating body 3, and camera S6B is attached to the rear end of the top surface of upper rotating body 3.

Each of the imaging devices S6 (camera S6F, camera S6B, camera S6L, and camera S6R) is, for example, a monocular wide-angle camera that provides a wide angle of view. Each of the imaging devices S6 may be a stereo camera or a distance imaging camera, etc. Images captured by each of the imaging devices S6 are input to the controller 30 via the display device 40.

The imaging device S6 as a spatial recognition device may function as an object detection device. In this case, the imaging device S6 may detect objects present around the shovel 100. Objects to be detected may include, for example, people, animals, vehicles, construction machinery, buildings, holes, etc. The imaging device S6 as an object detection device may calculate the distance from the imaging device S6 or the shovel 100 to the recognized object. The imaging device S6 as an object detection device may be a stereo camera or a distance image sensor, etc. Specifically, the imaging device S6 is a monocular camera having an imaging element such as a CCD or CMOS, and outputs the captured image to the display device 40.

In addition to the imaging device S6, the shovel 100 may be provided with other object detection devices, such as ultrasonic sensors, millimeter wave radar, LIDAR, and infrared sensors, as spatial recognition devices. A millimeter wave radar, ultrasonic sensor, laser radar, or the like, as a spatial recognition device, may emit multiple signals (such as laser light) toward an object and receive the reflected signals to detect the distance and direction of the object from the reflected signals.

A boom rod pressure sensor S7R and a boom bottom pressure sensor S7B are attached to the boom cylinder 7. An arm rod pressure sensor S8R and an arm bottom pressure sensor S8B are attached to the arm cylinder 8. A bucket rod pressure sensor S9R and a bucket bottom pressure sensor S9B are attached to the bucket cylinder 9. The boom rod pressure sensor S7R, the boom bottom pressure sensor S7B, the arm rod pressure sensor S8R, the arm bottom pressure sensor S8B, the bucket rod pressure sensor S9R, and the bucket bottom pressure sensor S9B are collectively referred to as the "cylinder pressure sensors."

The boom rod pressure sensor S7R detects the pressure in the rod side oil chamber of the boom cylinder 7 (hereinafter referred to as the "boom rod pressure"), and the boom bottom pressure sensor S7B detects the pressure in the bottom side oil chamber of the boom cylinder 7 (hereinafter referred to as the "boom bottom pressure"). The arm rod pressure sensor S8R detects the pressure in the rod side oil chamber of the arm cylinder 8 (hereinafter referred to as the "arm rod pressure"), and the arm bottom pressure sensor S8B detects the pressure in the bottom side oil chamber of the arm cylinder 8 (hereinafter referred to as the "arm bottom pressure"). The bucket rod pressure sensor S9R detects the pressure in the rod side oil chamber of the bucket cylinder 9 (hereinafter referred to as the "bucket rod pressure"), and the bucket bottom pressure sensor S9B detects the pressure in the bottom side oil chamber of the bucket cylinder 9 (hereinafter referred to as the "bucket bottom pressure").

The positioning device Q1 is configured to measure the position of the upper rotating body 3. In the illustrated example, the positioning device Q1 is a GNSS (Global Navigation Satellite System) compass that detects the position and orientation of the upper rotating body 3, and a detection signal corresponding to the position and orientation of the upper rotating body 3 is input to the controller 30. Note that the orientation of the upper rotating body 3 may be detected by another device, such as a direction sensor attached to the upper rotating body 3.

The communication device T1 is configured to communicate with an external device through any communication network including a mobile communication network, a satellite communication network, or the Internet. Specifically, the communication device T1 may be configured as a mobile communication module compatible with a mobile communication standard such as LTE (Long Term Evolution), 4G (4th Generation), or 5G (5th Generation), or a satellite communication module for connecting to a satellite communication network.

The machine guidance unit 50 is configured to execute a machine guidance function. In the illustrated example, the machine guidance unit 50 conveys work information such as the distance between the target point and the control point (for example, the working part of the end attachment) to the operator through the display device 40 or the sound output device 43. Data related to the target point is pre-stored in the storage device 47. The data related to the target point is expressed in a reference coordinate system. The reference coordinate system is, for example, the World Geodetic System. The World Geodetic System is a three-dimensional orthogonal XYZ coordinate system with the origin at the center of gravity of the earth, the X axis in the direction of the intersection of the Greenwich meridian and the equator, the Y axis in the direction of 90 degrees east longitude, and the Z axis in the direction of the North Pole. The operator may set an arbitrary point on the construction site as a reference point through the input device 42, and then set the relative positional relationship between the reference point and the target point. The working part of the end attachment is, for example, the tip (tip of the claw) of the bucket 6, or the back of the bucket 6, etc. The machine guidance unit 50 notifies the operator of work information via the display device 40 or the sound output device 43, etc., and guides the operator in operating the shovel 100 via the operating device 26.

The machine guidance unit 50 may also be configured to execute a machine control function. For example, when an operator is manually operating the machine, the machine guidance unit 50 may automatically operate at least one of the swing hydraulic motor 2A, the traveling hydraulic motor 2M, the boom 4, the arm 5, and the bucket 6 so that the target point and the control point (a point in the working portion of the end attachment) coincide with each other.

In the illustrated example, the machine guidance unit 50 acquires information from the boom angle sensor S1, arm angle sensor S2, bucket angle sensor S3, vehicle tilt sensor S4, turning state sensor S5, imaging device S6, positioning device Q1, communication device T1, input device 42, etc. Then, based on the acquired information, the machine guidance unit 50 calculates the distance between the target point and the control point, notifies the operator of the size of the distance between the target point and the control point by sound from the sound output device 43 and an image displayed on the display device 40, and automatically controls the operation of the actuator so that the control point and the target point coincide. The machine guidance unit 50 includes a position calculation unit 51, a distance calculation unit 52, an information transmission unit 53, an automatic control unit 54, a force calculation unit 55, and an excavation support unit 56 as functional elements related to the machine guidance function and the machine control function.

The position calculation unit 51 calculates the position of a predetermined positioning target. For example, the position calculation unit 51 calculates the coordinates of a control point in a reference coordinate system. Specifically, the position calculation unit 51 calculates the coordinates of the control point from the travel distance of the lower traveling body 1, the rotation angle of the upper rotating body 3, and the respective rotation angles (boom angle, arm angle, and bucket angle) of the boom 4, arm 5, and bucket 6, etc.

The distance calculation unit 52 is configured to calculate the distance between two positioning targets. In the illustrated example, the distance calculation unit 52 calculates the distance between a control point and a target point. For example, the distance calculation unit 52 calculates the distance between a control point on the tip of the bucket 6 and a point on a target construction surface.

The information transmission unit 53 transmits (notifies) various pieces of information to the operator of the shovel 100 through notification means such as the display device 40 or the sound output device 43. The information transmission unit 53 may notify the operator of the shovel 100 of the magnitude of various distances, etc. calculated by the distance calculation unit 52. For example, the information transmission unit 53 may convey the magnitude of the distance between the control point and the target point to the operator using at least one of visual information from the display device 40 and auditory information from the sound output device 43.

Specifically, the information transmission unit 53 may use intermittent sounds from the sound output device 43 to inform the operator of the distance between the control point and the target point. In this case, the information transmission unit 53 may shorten the interval of the intermittent sounds as the distance decreases, and may lengthen the interval of the intermittent sounds as the distance increases. The information transmission unit 53 may also use a continuous sound, or may express the difference in the distance by varying the pitch or intensity of the sound. The information transmission unit 53 may also issue an alarm through the sound output device 43 when the control point at the tip of the bucket 6 is lower than the target construction surface, that is, when it has passed beyond the target construction surface. This alarm is, for example, a continuous sound that is significantly louder than the intermittent sound.

The information transmission unit 53 may also cause the display device 40 to display, as work information, the distance between the control point and the target point, etc. The display device 40 may display the work information received from the information transmission unit 53 together with the image data received from the imaging device S6 under the control of the controller 30. The information transmission unit 53 may convey the distance to the operator using an image of an analog meter or a bar graph indicator, etc.

The automatic control unit 54 automatically assists the operator in manually operating the excavator 100 through the operating device 26 by automatically operating the actuators. Specifically, the automatic control unit 54 can individually and automatically adjust the pilot pressure acting on the pilot port of the control valve corresponding to each of the multiple hydraulic actuators. This allows the automatic control unit 54 to automatically operate each hydraulic actuator. The control of the machine control function by the automatic control unit 54 may be performed, for example, when a predetermined switch included in the input device 42 is pressed. The predetermined switch may be, for example, a machine control switch (hereinafter, "MC (Machine Control) switch"), and may be disposed as a knob switch at the tip of the grip of the operating device 26 (for example, an arm operating lever, which is a lever device used to operate the arm 5). The following description relates to the machine control function that is performed when the MC switch is pressed.

For example, when an MC switch or the like is pressed, the automatic control unit 54 automatically extends and retracts at least one of the boom cylinder 7 and the bucket cylinder 9 in accordance with the operation of the arm cylinder 8 in response to the operation of the arm operation lever in order to support excavation work. Specifically, when an operator manually performs a closing operation of the arm 5 (hereinafter, "arm closing operation"), the automatic control unit 54 automatically extends and retracts at least one of the boom cylinder 7 and the bucket cylinder 9 so that a target point on the target construction surface coincides with a control point on a work site such as the tip or back of the bucket 6. In this case, the operator can close the arm 5 while aligning the tip of the bucket 6 with the target construction surface, for example, simply by operating the arm operation lever in the arm closing direction.

The force calculation unit 55 is configured to calculate the excavation reaction force or the excavation force. The excavation reaction force is a reaction force to the excavation force, and is a force having the same magnitude as the excavation force and directed in the opposite direction to the excavation force. Therefore, calculating the excavation reaction force is equivalent to calculating the excavation force. In the illustrated example, the force calculation unit 55 derives the excavation force based on the attitude of the excavation attachment and the load acting on the excavation attachment. The attitude of the excavation attachment is detected by an attitude sensor. The attitude sensor includes at least one of a boom angle sensor S1, an arm angle sensor S2, and a bucket angle sensor S3. The load acting on the excavation attachment is detected by a cylinder pressure sensor. The cylinder pressure sensor includes at least one of a boom rod pressure sensor S7R, a boom bottom pressure sensor S7B, an arm rod pressure sensor S8R, an arm bottom pressure sensor S8B, a bucket rod pressure sensor S9R, and a bucket bottom pressure sensor S9B.

Specifically, the force calculation unit 55 repeatedly derives the excavation force at a predetermined calculation period using a predetermined calculation formula. The force calculation unit 55 may also correct the derived excavation force taking into account soil characteristics such as soil density. The value representing the soil characteristics may be a value input by the operator through the input device 42 or the like, or may be a value automatically calculated based on the output of various sensors such as an image sensor (imaging device S6) or a cylinder pressure sensor. In the illustrated example, the force calculation unit 55 may be configured to calculate the vertical component of the excavation force. The vertical component of the excavation force is a component in a direction perpendicular to a straight line connecting the fulcrum (center of rotation) when the machine body is lifted and the point of action of the excavation force (for example, the tip of the bucket 6). The moment of the vertical component of the excavation force around the fulcrum is a reaction moment to the moment of the vertical component of the excavation reaction force around the fulcrum, and the moment of the vertical component of the excavation reaction force around the fulcrum is the moment of the force that causes the machine body to lift up.

The excavation support unit 56 is configured to support the excavation operation performed by the operator of the excavator 100. For example, the excavation support unit 56 is configured to prevent the lower traveling body 1 from rotating about the fulcrum during the excavation operation, causing the front end of the upper rotating body 3 to rise up. Specifically, the excavation support unit 56 is configured to automatically raise the boom 4 when the value of the excavation force repeatedly calculated during the excavation operation exceeds a predetermined value. In the illustrated example, the excavation support unit 56 is configured to automatically raise the boom 4 when the value of the vertical component of the excavation force repeatedly calculated during the excavation operation exceeds a predetermined value TH.

In the illustrated example, the predetermined value TH is a value calculated based on the vertical component of the maximum allowable excavation force, which is the maximum value of the excavation force that does not cause the machine body to lift up, and is, for example, a value obtained by multiplying the value of the vertical component of the maximum allowable excavation force by a predetermined ratio (for example, 0.8). The value of the vertical component of the maximum allowable excavation force is a value calculated based on the attitude of the excavation attachment. Furthermore, the predetermined ratio is typically a value less than 1.0, but may be 1.0.

Specifically, when the value of the vertical component of the excavation force exceeds a predetermined value TH, the excavation support unit 56 automatically raises the boom 4 so that the raising speed of the boom 4 increases as the excess, which is the difference between the value of the vertical component of the excavation force and the predetermined value TH, increases. In this case, the excavation support unit 56 may determine the magnitude of the control command for the solenoid valve 31 corresponding to the boom cylinder 7 based on the magnitude of the excess.

In addition, when the value of the vertical component of the excavation force exceeds a predetermined value TH, the excavation support unit 56 may automatically raise the boom 4 so that the point of application of the excavation force moves toward the fulcrum. In this case, the excavation support unit 56 may determine the magnitude of the control command for the solenoid valve 31 corresponding to the boom cylinder 7 based on the magnitude of the arm closing speed. The arm closing speed corresponds to the rotation angle of the arm 5 per unit time, the extension amount of the arm cylinder 8 per unit time, the increment of the arm closing side pilot pressure per unit time, or the operation amount (tilt angle) or operation speed (tilt angular speed) of the arm operating lever, etc.

The excavation support unit 56 may be configured to simultaneously determine the magnitude of the control command for the solenoid valve 31 based on the magnitude of the excess and the magnitude of the control command for the solenoid valve 31 based on the magnitude of the arm closing speed. In this case, the excavation support unit 56 may be configured to determine the magnitude of the control command to be finally output to the solenoid valve 31 by correcting the magnitude of the control command determined based on the magnitude of the excess by the magnitude of the control command determined based on the magnitude of the arm closing speed. Alternatively, the excavation support unit 56 may be configured to adopt the larger of the control command determined based on the magnitude of the excess and the control command determined based on the magnitude of the arm closing speed as the control command to be finally output to the solenoid valve 31.

Next, the hydraulic system of the excavator 100 will be described with reference to FIG. 3. FIG. 3 is a diagram showing a schematic configuration example of the hydraulic system of the excavator 100. Note that in FIG. 3, the mechanical power transmission lines, hydraulic oil lines, pilot lines, and electrical signal lines are shown by double lines, solid lines, dashed lines, and dotted lines, respectively, as in FIG. 2 and the like.

The hydraulic system circulates hydraulic oil from the left main pump 14L driven by the engine 11 to the hydraulic oil tank via the left center bypass oil passage C1L and the left parallel oil passage C2L, and also circulates hydraulic oil from the right main pump 14R driven by the engine 11 to the hydraulic oil tank via the right center bypass oil passage C1R and the right parallel oil passage C2R.

The left center bypass oil passage C1L starts at the left main pump 14L, passes through the control valves 171, 173, 175L, and 176L arranged in the control valve unit 17, and reaches the hydraulic oil tank.

The right center bypass oil passage C1R starts at the right main pump 14R, passes through the control valves 172, 174, 175R, and 176R arranged in the control valve unit 17, and reaches the hydraulic oil tank.

The control valve 171 is a spool valve that supplies hydraulic oil discharged from the left main pump 14L to the left traveling hydraulic motor 2ML and discharges hydraulic oil discharged by the left traveling hydraulic motor 2ML into the hydraulic oil tank.

The control valve 172 is a spool valve that supplies hydraulic oil discharged from the right main pump 14R to the right traveling hydraulic motor 2MR and discharges hydraulic oil discharged by the right traveling hydraulic motor 2MR to the hydraulic oil tank.

The control valve 173 is a spool valve that supplies hydraulic oil discharged from the left main pump 14L to the swing hydraulic motor 2A and discharges hydraulic oil discharged by the swing hydraulic motor 2A into the hydraulic oil tank.

The control valve 174 is a spool valve that supplies hydraulic oil discharged from the right main pump 14R to the bucket cylinder 9 and also discharges the hydraulic oil in the bucket cylinder 9 to the hydraulic oil tank.

The control valve 175 includes control valve 175L and control valve 175R. Control valve 175L is a spool valve that supplies hydraulic oil discharged by the left main pump 14L to the boom cylinder 7 and discharges the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank. Control valve 175R is a spool valve that supplies hydraulic oil discharged by the right main pump 14R to the boom cylinder 7 and discharges the hydraulic oil in the boom cylinder 7 to the hydraulic oil tank.

The control valve 176 includes a control valve 176L and a control valve 176R. The control valve 176L is a spool valve that supplies hydraulic oil discharged by the left main pump 14L to the arm cylinder 8 and discharges the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank. The control valve 176R is a spool valve that supplies hydraulic oil discharged by the right main pump 14R to the arm cylinder 8 and discharges the hydraulic oil in the arm cylinder 8 to the hydraulic oil tank.

Each of the control valves 171 to 176 adjusts the flow rate and/or switches the flow direction of the hydraulic oil supplied to the hydraulic actuator depending on the pilot pressure acting on the pilot port.

The left parallel oil passage C2L is arranged in parallel with the left center bypass oil passage C1L and is configured to supply hydraulic oil discharged by the left main pump 14L to each of the control valves 173, 175L, and 176L. This allows the left parallel oil passage C2L to supply hydraulic oil to a downstream control valve when the flow of hydraulic oil through the left center bypass oil passage C1L is restricted or blocked by either the control valve 171, 173, or 175L.

The right parallel oil passage C2R is arranged in parallel with the right center bypass oil passage C1R and is configured to be able to supply hydraulic oil discharged by the right main pump 14R to each of the control valves 174, 175R, and 176R. This allows the right parallel oil passage C2R to supply hydraulic oil to a more downstream control valve when the flow of hydraulic oil through the right center bypass oil passage C1R is restricted or blocked by any of the control valves 172, 174, or 175R.

The left regulator 13L is configured to adjust the discharge volume of the left main pump 14L by adjusting the tilt angle of the swash plate of the left main pump 14L under the control of the controller 30. The right regulator 13R is configured to adjust the discharge volume of the right main pump 14R by adjusting the tilt angle of the swash plate of the right main pump 14R under the control of the controller 30.

The left discharge pressure sensor 28L detects the discharge pressure of the left main pump 14L, and a detection signal corresponding to the detected discharge pressure is input to the controller 30. The same is true for the right discharge pressure sensor 28R. This allows the controller 30 to control the left regulator 13L according to the discharge pressure of the left main pump 14L, and to control the right regulator 13R according to the discharge pressure of the right main pump 14R.

A left throttle 18L is provided in the left center bypass oil passage C1L between the most downstream control valve 176L and the hydraulic oil tank. As a result, the flow of hydraulic oil discharged by the left main pump 14L is restricted by the left throttle 18L. The left throttle 18L generates a left control pressure for controlling the left regulator 13L. A right throttle 18R is provided in the right center bypass oil passage C1R between the most downstream control valve 176R and the hydraulic oil tank. As a result, the flow of hydraulic oil discharged by the right main pump 14R is restricted by the right throttle 18R. The right throttle 18R generates a right control pressure for controlling the right regulator 13R.

The left control pressure sensor 19L detects the left control pressure, and a detection signal corresponding to the detected left control pressure is input to the controller 30. The right control pressure sensor 19R detects the right control pressure, and a detection signal corresponding to the detected right control pressure is input to the controller 30.

The controller 30 may control the left regulator 13L in response to the discharge pressure of the left main pump 14L detected by the left discharge pressure sensor 28L, and adjust the discharge volume of the left main pump 14L. For example, the controller 30 may control the left regulator 13L in response to an increase in the discharge pressure of the left main pump 14L, and reduce the discharge volume of the left main pump 14L by adjusting the swash plate tilt angle of the left main pump 14L. The same applies to the right regulator 13R. This allows the controller 30 to control the total horsepower of the main pump 14 so that the absorption horsepower of the main pump 14, which is expressed as the product of the discharge pressure and the discharge volume, does not exceed the output horsepower of the engine 11.

The controller 30 may also adjust the discharge volume of the left main pump 14L by controlling the left regulator 13L according to the left control pressure detected by the left control pressure sensor 19L. For example, the controller 30 decreases the discharge volume of the left main pump 14L as the left control pressure increases, and increases the discharge volume of the left main pump 14L as the left control pressure decreases. The same applies to the discharge volume of the right main pump 14R.

Specifically, in the case of a standby state (state shown in FIG. 3) in which none of the hydraulic actuators in the excavator 100 are operated, the hydraulic oil discharged by the left main pump 14L passes through the left center bypass oil passage C1L to the left throttle 18L. The flow of the hydraulic oil discharged by the left main pump 14L increases the left control pressure generated upstream of the left throttle 18L. As a result, the controller 30 reduces the discharge amount of the left main pump 14L to the allowable minimum discharge amount, suppressing the pressure loss (pumping loss) when the hydraulic oil discharged by the left main pump 14L passes through the left center bypass oil passage C1L. The same applies to the pressure loss (pumping loss) when the hydraulic oil discharged by the right main pump 14R passes through the right center bypass oil passage C1R.

On the other hand, when any of the hydraulic actuators is operated through the operating device 26, the hydraulic oil discharged from the left main pump 14L flows into the hydraulic actuator to be operated via the control valve corresponding to the hydraulic actuator to be operated. The flow of hydraulic oil discharged from the left main pump 14L reduces or eliminates the amount of hydraulic oil reaching the left throttle 18L, lowering the left control pressure generated upstream of the left throttle 18L. As a result, the controller 30 increases the discharge volume of the left main pump 14L, circulating sufficient hydraulic oil to the hydraulic actuator to be operated, and reliably driving the hydraulic actuator to be operated. The same applies to the hydraulic oil discharged from the right main pump 14R.

Next, the configuration for the controller 30 to operate the actuators will be described with reference to Figures 4A to 4F. Figures 4A to 4F are diagrams of parts of the hydraulic system. Specifically, Figure 4A is a diagram of the hydraulic system portion related to the operation of the arm cylinder 8, and Figure 4B is a diagram of the hydraulic system portion related to the operation of the boom cylinder 7. Figure 4C is a diagram of the hydraulic system portion related to the operation of the bucket cylinder 9, and Figure 4D is a diagram of the hydraulic system portion related to the operation of the swing hydraulic motor 2A. Figure 4E is a diagram of the hydraulic system portion related to the operation of the left traveling hydraulic motor 2ML, and Figure 4F is a diagram of the hydraulic system portion related to the operation of the right traveling hydraulic motor 2MR.

As shown in Figures 4A to 4F, the hydraulic system includes solenoid valves 31. Solenoid valves 31 include solenoid valves 31AL to 31FL and solenoid valves 31AR to 31FR.

The solenoid valve 31 is disposed in a pipe connecting the pilot pump 15 and the pilot port of the corresponding control valve in the control valve unit 17, and is configured to be able to change the flow area of the pipe by changing the opening area. In this embodiment, the solenoid valve 31 is an electromagnetic proportional valve, and operates in response to a control command output by the controller 30. Therefore, the controller 30 can supply the pilot oil discharged by the pilot pump 15 to the pilot port of the corresponding control valve in the control valve unit 17 via the solenoid valve 31 in response to the operation of the operating device 26 by the operator, or regardless of the operation of the operating device 26 by the operator. Then, the controller 30 can apply the pilot pressure generated by the solenoid valve 31 to the pilot port of the corresponding control valve.

With this configuration, the controller 30 can operate the hydraulic actuator corresponding to a specific operating device 26 not only when an operation is being performed on the specific operating device 26, but also when no operation is being performed on the specific operating device 26. Furthermore, the controller 30 can forcibly stop the operation of the hydraulic actuator corresponding to the specific operating device 26 even when an operation is being performed on the specific operating device 26.

For example, as shown in FIG. 4A, the left operating lever 26L is used to operate the arm 5. Specifically, the left operating lever 26L uses pilot oil discharged by the pilot pump 15 to apply pilot pressure corresponding to the operation in the forward and backward directions to the pilot port of the control valve 176. In this case, the left operating lever 26L functions as an arm operating lever. More specifically, when the left operating lever 26L is operated in the arm closing direction (rearward direction), it applies pilot pressure corresponding to the operation amount to the right pilot port (arm closing side pilot port) of the control valve 176L and the left pilot port (arm closing side pilot port) of the control valve 176R. Also, when the left operating lever 26L is operated in the arm opening direction (forward direction), it applies pilot pressure corresponding to the operation amount to the left pilot port (arm opening side pilot port) of the control valve 176L and the right pilot port (arm opening side pilot port) of the control valve 176R.

The operation device 26 is provided with a switch SW. In this embodiment, the switch SW includes a switch SW1 and a switch SW2. The switch SW1 is an MC switch (push button switch) provided at the tip of the left operation lever 26L. The operator can operate the left operation lever 26L while pressing the switch SW1. The switch SW1 may be provided on the right operation lever 26R or at another position in the cabin 10. The switch SW2 is an MC switch (push button switch) provided at the tip of the left travel lever 26DL. The operator can operate the left travel lever 26DL while pressing the switch SW2. The switch SW2 may be provided on the right travel lever 26DR or at another position in the cabin 10.

The operation sensor 29LA detects the forward/rearward operation of the left operating lever 26L by the operator and outputs the detected value to the controller 30.

The solenoid valve 31AL operates in response to a control command (current command) output by the controller 30. The solenoid valve 31AL adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the right pilot port of the control valve 176L and the left pilot port of the control valve 176R via the solenoid valve 31AL. The solenoid valve 31AR operates in response to a control command (current command) output by the controller 30. The solenoid valve 31AR adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the left pilot port of the control valve 176L and the right pilot port of the control valve 176R via the solenoid valve 31AR. The solenoid valve 31AL can adjust the pilot pressure so that the control valve 176L and the control valve 176R can be stopped at any valve position. Similarly, the solenoid valve 31AR can adjust the pilot pressure so that the control valve 176L and the control valve 176R can be stopped at any valve position.

With this configuration, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the right pilot port of the control valve 176L and the left pilot port of the control valve 176R via the solenoid valve 31AL in response to the arm closing operation by the operator. The controller 30 can also supply pilot oil discharged by the pilot pump 15 to the right pilot port of the control valve 176L and the left pilot port of the control valve 176R via the solenoid valve 31AL, regardless of the arm closing operation by the operator. In other words, the controller 30 can close the arm 5 in response to the arm closing operation by the operator or regardless of the arm closing operation by the operator. In this way, the solenoid valve 31AL functions as an "arm solenoid valve" or an "arm closing solenoid valve".

In addition, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the left pilot port of the control valve 176L and the right pilot port of the control valve 176R via the solenoid valve 31AR in response to the arm opening operation by the operator. In addition, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the left pilot port of the control valve 176L and the right pilot port of the control valve 176R via the solenoid valve 31AR, regardless of the arm opening operation by the operator. In other words, the controller 30 can open the arm 5 in response to the arm opening operation by the operator or regardless of the arm opening operation by the operator. In this way, the solenoid valve 31AR functions as an "arm solenoid valve" or an "arm opening solenoid valve".

In addition, with this configuration, even if the operator is performing an arm closing operation, the controller 30 can, if necessary, reduce the pilot pressure acting on the pilot ports on the closing side of the control valve 176 (the left pilot port of the control valve 176L and the right pilot port of the control valve 176R) to forcibly stop the closing operation of the arm 5. The same applies to the case where the opening operation of the arm 5 is forcibly stopped when the operator is performing an arm opening operation.

Alternatively, even if the operator is performing an arm closing operation, the controller 30 may, as necessary, control the solenoid valve 31AR to increase the pilot pressure acting on the opening pilot port of the control valve 176 (the right pilot port of control valve 176L and the left pilot port of control valve 176R) opposite the closing pilot port of the control valve 176, and forcibly return the control valve 176 to the neutral position, thereby forcibly stopping the closing operation of the arm 5. The same applies to the case where the opening operation of the arm 5 is forcibly stopped when the operator is performing an arm opening operation.

Although the following explanation with reference to Figures 4B to 4F is omitted, the same applies to the case where the operation of the boom 4 is forcibly stopped when the operator is performing a boom-raising or boom-lowering operation, the case where the operation of the bucket 6 is forcibly stopped when the operator is performing a bucket-closing or bucket-opening operation, and the case where the rotation operation of the upper rotating body 3 is forcibly stopped when the operator is performing a rotation operation. The same also applies to the case where the traveling operation of the lower traveling body 1 is forcibly stopped when the operator is performing a traveling operation.

The controller 30 may also be configured to apply a small pilot pressure to the pilot ports on both sides of the control valve 176 before the arm operation (arm closing operation and arm opening operation) is performed, in order to improve the responsiveness of the arm operation. The same applies to other operations such as boom operation (boom raising operation and boom lowering operation). In other words, the controller 30 can increase the responsiveness of the hydraulic actuator by using more pilot oil.

Also, as shown in FIG. 4B, the right operating lever 26R is used to operate the boom 4. Specifically, the right operating lever 26R uses pilot oil discharged by the pilot pump 15 to apply pilot pressure corresponding to the operation in the forward and backward directions to the pilot port of the control valve 175. In this case, the right operating lever 26R functions as a boom operating lever. More specifically, when the right operating lever 26R is operated in the boom-up direction (rearward), it applies pilot pressure corresponding to the operation amount to the right pilot port (boom-up side pilot port) of the control valve 175L and the left pilot port (boom-up side pilot port) of the control valve 175R. Also, when the right operating lever 26R is operated in the boom-down direction (forward), it applies pilot pressure corresponding to the operation amount to the right pilot port (boom-down side pilot port) of the control valve 175R.

The operation sensor 29RA detects the forward/rearward operation of the right operating lever 26R by the operator and outputs the detected value to the controller 30.

The solenoid valve 31BL operates in response to a control command (current command) output by the controller 30. It adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the right pilot port of the control valve 175L and the left pilot port of the control valve 175R via the solenoid valve 31BL. The solenoid valve 31BR operates in response to a control command (current command) output by the controller 30. It adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the right pilot port of the control valve 175R via the solenoid valve 31BR. The solenoid valve 31BL can adjust the pilot pressure so that the control valve 175L and the control valve 175R can be stopped at any valve position. The solenoid valve 31BR can also adjust the pilot pressure so that the control valve 175R can be stopped at any valve position.

With this configuration, the controller 30 can supply pilot oil discharged from the pilot pump 15 to the right pilot port of the control valve 175L and the left pilot port of the control valve 175R via the solenoid valve 31BL in response to the boom-raising operation by the operator. The controller 30 can also supply pilot oil discharged from the pilot pump 15 to the right pilot port of the control valve 175L and the left pilot port of the control valve 175R via the solenoid valve 31BL, regardless of the boom-raising operation by the operator. In other words, the controller 30 can raise the boom 4 in response to the boom-raising operation by the operator or regardless of the boom-raising operation by the operator. In this way, the solenoid valve 31BL functions as a "boom solenoid valve" or a "boom-raising solenoid valve".

In addition, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the right pilot port of the control valve 175R via the solenoid valve 31BR in response to the boom lowering operation by the operator. In addition, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the right pilot port of the control valve 175R via the solenoid valve 31BR, regardless of the boom lowering operation by the operator. In other words, the controller 30 can lower the boom 4 in response to the boom lowering operation by the operator or regardless of the boom lowering operation by the operator. In this way, the solenoid valve 31BR functions as a "boom solenoid valve" or a "boom lowering solenoid valve".

As shown in FIG. 4C, the right operating lever 26R is also used to operate the bucket 6. Specifically, the right operating lever 26R uses pilot oil discharged by the pilot pump 15 to apply pilot pressure corresponding to left/right operation to the pilot port of the control valve 174. In this case, the right operating lever 26R functions as a bucket operating lever. More specifically, when the right operating lever 26R is operated in the bucket closing direction (left direction), it applies pilot pressure corresponding to the operation amount to the left pilot port of the control valve 174. Also, when the right operating lever 26R is operated in the bucket opening direction (right direction), it applies pilot pressure corresponding to the operation amount to the right pilot port of the control valve 174.

The operation sensor 29RB detects the left/right operation of the right operating lever 26R by the operator and outputs the detected value to the controller 30. If the bucket angle sensor S3 is omitted, the controller 30 may estimate the bucket angle based on the output of the operation sensor 29RB.

The solenoid valve 31CL operates in response to a control command (current command) output by the controller 30. It adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the left pilot port of the control valve 174 via the solenoid valve 31CL. The solenoid valve 31CR operates in response to a control command (current command) output by the controller 30. It adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the right pilot port of the control valve 174 via the solenoid valve 31CR. The solenoid valve 31CL can adjust the pilot pressure so that the control valve 174 can be stopped at any valve position. Similarly, the solenoid valve 31CR can adjust the pilot pressure so that the control valve 174 can be stopped at any valve position.

With this configuration, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the left pilot port of the control valve 174 via the solenoid valve 31CL in response to the bucket closing operation by the operator. The controller 30 can also supply pilot oil discharged by the pilot pump 15 to the left pilot port of the control valve 174 via the solenoid valve 31CL, regardless of the bucket closing operation by the operator. In other words, the controller 30 can close the bucket 6 in response to the bucket closing operation by the operator, or regardless of the bucket closing operation by the operator. In this way, the solenoid valve 31CL functions as a "bucket solenoid valve" or a "bucket closing solenoid valve".

In addition, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the right pilot port of the control valve 174 via the solenoid valve 31CR in response to the bucket opening operation by the operator. In addition, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the right pilot port of the control valve 174 via the solenoid valve 31CR, regardless of the bucket opening operation by the operator. In other words, the controller 30 can open the bucket 6 in response to the bucket opening operation by the operator, or regardless of the bucket opening operation by the operator. In this way, the solenoid valve 31CR functions as a "solenoid valve for bucket" or a "solenoid valve for bucket opening".

As shown in FIG. 4D, the left operating lever 26L is also used to operate the turning mechanism 2. Specifically, the left operating lever 26L uses pilot oil discharged by the pilot pump 15 to apply pilot pressure corresponding to the operation in the left and right direction to the pilot port of the control valve 173. In this case, the left operating lever 26L functions as a turning operating lever. More specifically, when the left operating lever 26L is operated in the left turning direction (left direction), it applies pilot pressure corresponding to the operation amount to the left pilot port of the control valve 173. Also, when the left operating lever 26L is operated in the right turning direction (right direction), it applies pilot pressure corresponding to the operation amount to the right pilot port of the control valve 173.

The operation sensor 29LB detects the left/right operation of the left operating lever 26L by the operator and outputs the detected value to the controller 30.

The solenoid valve 31DL operates in response to a control command (current command) output by the controller 30. It adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the left pilot port of the control valve 173 via the solenoid valve 31DL. The solenoid valve 31DR operates in response to a control command (current command) output by the controller 30. It adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the right pilot port of the control valve 173 via the solenoid valve 31DR. The solenoid valve 31DL can adjust the pilot pressure so that the control valve 173 can be stopped at any valve position. Similarly, the solenoid valve 31DR can adjust the pilot pressure so that the control valve 173 can be stopped at any valve position.

With this configuration, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the left pilot port of the control valve 173 via the solenoid valve 31DL in response to a left turning operation by the operator. The controller 30 can also supply pilot oil discharged by the pilot pump 15 to the left pilot port of the control valve 173 via the solenoid valve 31DL, regardless of a left turning operation by the operator. In other words, the controller 30 can rotate the turning mechanism 2 to the left in response to a left turning operation by the operator or regardless of a left turning operation by the operator. In this way, the solenoid valve 31DL functions as a "swing solenoid valve" or a "left turning solenoid valve".

In addition, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the right pilot port of the control valve 173 via the solenoid valve 31DR in response to a right turning operation by the operator. In addition, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the right pilot port of the control valve 173 via the solenoid valve 31DR, regardless of a right turning operation by the operator. In other words, the controller 30 can rotate the turning mechanism 2 to the right in response to a right turning operation by the operator or regardless of a right turning operation by the operator. In this way, the solenoid valve 31DR functions as a "swing solenoid valve" or a "right turning solenoid valve".

Also, as shown in FIG. 4E, the left travel lever 26DL is used to operate the left crawler 1CL. Specifically, the left travel lever 26DL uses pilot oil discharged by the pilot pump 15 to apply pilot pressure corresponding to the operation in the forward and backward directions to the pilot port of the control valve 171. More specifically, when the left travel lever 26DL is operated in the forward direction (forward direction), it applies pilot pressure corresponding to the operation amount to the left pilot port of the control valve 171. Also, when the left travel lever 26DL is operated in the reverse direction (rearward direction), it applies pilot pressure corresponding to the operation amount to the right pilot port of the control valve 171.

The operation sensor 29DL electrically detects the forward/rearward operation of the left travel lever 26DL by the operator and outputs the detected value to the controller 30.

The solenoid valve 31EL operates in response to a current command output by the controller 30. The solenoid valve 31EL adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the left pilot port of the control valve 171 via the solenoid valve 31EL. The solenoid valve 31ER operates in response to a current command output by the controller 30. The solenoid valve 31ER adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the right pilot port of the control valve 171 via the solenoid valve 31ER. The solenoid valves 31EL and 31ER can adjust the pilot pressure so that the control valve 171 can be stopped at any valve position.

With this configuration, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the left pilot port of the control valve 171 via the solenoid valve 31EL, regardless of the left forward movement operation by the operator. In other words, the left crawler 1CL can be moved forward. Also, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the right pilot port of the control valve 171 via the solenoid valve 31ER, regardless of the left reverse movement operation by the operator. In other words, the left crawler 1CL can be moved backward. In this way, the solenoid valve 31EL functions as a "left running solenoid valve" or a "left forward running solenoid valve", and the solenoid valve 31ER functions as a "left running solenoid valve" or a "left reverse running solenoid valve".

As shown in FIG. 4F, the right travel lever 26DR is used to operate the right crawler 1CR. Specifically, the right travel lever 26DR uses pilot oil discharged by the pilot pump 15 to apply pilot pressure corresponding to the operation in the forward and backward directions to the pilot port of the control valve 172. More specifically, when the right travel lever 26DR is operated in the forward direction (forward direction), it applies pilot pressure corresponding to the operation amount to the right pilot port of the control valve 172. Also, when the right travel lever 26DR is operated in the reverse direction (rearward direction), it applies pilot pressure corresponding to the operation amount to the left pilot port of the control valve 172.

The operation sensor 29DR electrically detects the forward/rearward operation of the right travel lever 26DR by the operator and outputs the detected value to the controller 30.

The solenoid valve 31FL operates in response to a current command output by the controller 30. The solenoid valve 31FL adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the left pilot port of the control valve 172 via the solenoid valve 31FL. The solenoid valve 31FR operates in response to a current command output by the controller 30. The solenoid valve 31FR adjusts the pilot pressure by the pilot oil introduced from the pilot pump 15 to the right pilot port of the control valve 172 via the solenoid valve 31FR. The solenoid valves 31FL and 31FR can adjust the pilot pressure so that the control valve 172 can be stopped at any valve position.

With this configuration, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the right pilot port of the control valve 172 via the solenoid valve 31FL, regardless of the right forward movement operation by the operator. In other words, the right crawler 1CR can be moved forward. Also, the controller 30 can supply pilot oil discharged by the pilot pump 15 to the left pilot port of the control valve 172 via the solenoid valve 31FR, regardless of the right reverse movement operation by the operator. In other words, the right crawler 1CR can be moved backward. In this way, the solenoid valve 31FL functions as a "right running solenoid valve" or a "right forward running solenoid valve", and the solenoid valve 31FR functions as a "right running solenoid valve" or a "right reverse running solenoid valve".

The excavator 100 may also be configured to automatically operate the bucket tilt mechanism. In this case, the hydraulic system portion related to the bucket tilt cylinder that constitutes the bucket tilt mechanism may be configured in the same manner as the hydraulic system portion related to the operation of the boom cylinder 7, etc.

Although the description has been given of an electric operation lever as the form of the operation device 26, a hydraulic operation lever may be used instead of an electric operation lever. In this case, the operation amount of the hydraulic operation lever may be detected in the form of pressure by a pressure sensor and input to the controller 30. In addition, a solenoid valve may be disposed between the operation device 26 as a hydraulic operation lever and the pilot port of each control valve. The solenoid valve is configured to operate in response to an electric signal from the controller 30. With this configuration, when manual operation is performed using the operation device 26 as a hydraulic operation lever, the operation device 26 can move each control valve by increasing or decreasing the pilot pressure in response to the operation amount. In addition, each control valve may be configured as an electromagnetic spool valve. In this case, the electromagnetic spool valve operates in response to an electric signal from the controller 30 corresponding to the operation amount of the electric operation lever.

Next, referring to FIG. 5, the relationship of forces acting on the shovel 100 when excavation is performed will be described. FIG. 5 is a diagram showing the relationship of forces acting on the shovel 100 when excavation is performed. For ease of explanation, FIG. 5 shows the relationship of forces acting on the shovel 100 when excavation is performed by the shovel 100 located on a horizontal plane.

First, we will explain the parameters related to the control to prevent the body of the shovel 100 from floating up during excavation operations.

In FIG. 5, point P1 indicates the connection point between the upper rotating body 3 and the boom 4. Point P2 indicates the connection point between the upper rotating body 3 and the cylinder of the boom cylinder 7. Point P3 indicates the connection point between the rod 7C of the boom cylinder 7 and the boom 4. Point P4 indicates the connection point between the boom 4 and the cylinder of the arm cylinder 8. Point P5 indicates the connection point between the rod 8C of the arm cylinder 8 and the arm 5. Point P6 indicates the connection point between the boom 4 and the arm 5. Point P7 indicates the connection point between the arm 5 and the bucket 6. Point P8 indicates the point of action of the excavation force (the tip of the bucket 6). Note that for clarity, the bucket cylinder 9 is not shown in FIG. 5.

In addition, FIG. 5 shows the angle between the horizontal line and the line connecting points P1 and P3 as boom angle θ1, the angle between the line connecting points P3 and P6 and the line connecting points P6 and P7 as arm angle θ2, and the angle between the line connecting points P6 and P7 and the line connecting points P7 and P8 as bucket angle θ3. The boom angle θ1 is detected by boom angle sensor S1, the arm angle θ2 is detected by arm angle sensor S2, and the bucket angle θ3 is detected by bucket angle sensor S3.

In addition, in FIG. 5, distance D1 indicates the horizontal distance between the center of rotation RC, which is the fulcrum when lift-up of the machine body occurs, and the center of gravity GC of the shovel 100, i.e., the distance between the line of action of gravity M·g, which is the product of the mass M of the shovel 100 and the gravitational acceleration g, and the center of rotation RC. The product of distance D1 and the magnitude of gravity M·g represents the magnitude of the moment of the first force around the center of rotation RC. Note that the symbol "·" is a multiplication symbol. Also, point P8, which is the point of application of the excavation force, and the center of rotation RC are both located on a horizontal plane.

In addition, in FIG. 5, distance D2 indicates the horizontal distance between the center of rotation RC and point P8, i.e., the distance between the line of action of the vertical component FR1 of the excavation reaction force FR and the center of rotation RC. The product of distance D2 and the magnitude of the vertical component FR1 represents the magnitude of the second force moment around the center of rotation RC. The excavation reaction force FR forms an excavation angle θ with respect to the vertical line, and the vertical component FR1 of the excavation reaction force FR is expressed as FR1 = FR × cos θ. The excavation angle θ is calculated based on the boom angle θ1, the arm angle θ2, and the bucket angle θ3.

In addition, in FIG. 5, distance D3 indicates the distance between the line connecting points P2 and P3 and the center of rotation RC, i.e., the distance between the line of action of force FB attempting to pull out rod 7C of boom cylinder 7 and the center of rotation RC. The product of distance D3 and the magnitude of force FB represents the magnitude of the third force moment around the center of rotation RC.

In addition, in FIG. 5, distance D4 indicates the distance between the line of action of the excavation reaction force FR and point P6. The product of distance D4 and the magnitude of the excavation reaction force FR represents the magnitude of the first force moment about point P6.

In addition, in FIG. 5, distance D5 indicates the distance between point P6 and the straight line connecting points P4 and P5, i.e., the distance between point P6 and the line of action of arm thrust FA that closes arm 5. The product of distance D5 and the magnitude of arm thrust FA represents the magnitude of the second force moment around point P6.

Here, it is assumed that the vertical component FR1 of the excavation reaction force FR can be replaced with the force moment tending to lift the shovel about the center of rotation RC and the force FB tending to pull out the rod 7C of the boom cylinder 7 tending to lift the shovel about the center of rotation RC. In this case, the relationship between the magnitude of the second force moment about the center of rotation RC and the magnitude of the third force moment about the center of rotation RC is expressed by the following equation (1).
FR1・D2=FR・cosθ・D2=FB・D3...(1)
It is also considered that the force moment of the arm thrust force FA attempting to close the arm 5 about point P6 and the force moment of the excavation reaction force FR attempting to open the arm 5 about point P6 are balanced. In this case, the relationship between the magnitude of the first force moment about point P6 and the magnitude of the second force moment about point P6 is expressed by the following formulas (2) and (2)'. Note that the symbol "/" is a division symbol.
FA・D5=FR・D4...(2)
FR=FA・D5/D4...(2)'
Further, from equations (1) and (2), the force FB attempting to pull out the rod 7C of the boom cylinder 7 is expressed by the following equation (3).
FB=FA・D2・D5・cosθ/(D3・D4)...(3)
5, if the annular pressure-receiving area of the piston facing rod-side oil chamber 7R of boom cylinder 7 is area A1 and the pressure of the hydraulic oil in rod-side oil chamber 7R is pressure PB, then force FB attempting to pull out rod 7C of boom cylinder 7 is expressed as FB = PB · A1. Therefore, formula (3) can be expressed by the following formulas (4) and (4)'.
PB=FA・D2・D5・cosθ/(A1・D3・D4)...(4)
FA=PB・A1・D3・D4/(D2・D5・cosθ)...(4)'
Here, if the force FB that tries to pull out the rod 7C of the boom cylinder 7 when the machine body is lifted is defined as a force FBmax, then the moment of the first force about the center of rotation RC that prevents gravity M·g from lifting the machine body and the moment of the third force about the center of rotation RC that tries to lift the machine body by the force FBmax are considered to be in balance. In this case, the relationship in magnitude between the moments of these two forces is expressed by the following equation (5).
M・g・D1=FBmax・D3...(5)
In addition, if the pressure of the hydraulic oil in the rod side oil chamber 7R of the boom cylinder 7 at this time is the maximum allowable pressure PBmax, which is the maximum pressure that does not cause the aircraft body to lift up, the maximum allowable pressure PBmax is expressed by the following equation (6).
PBmax=M・g・D1/(A1・D3)...(6)
The distance D1 is a value determined according to the swing angle, while the distances D2 and D3 are values determined according to the swing angle and the attitude of the excavation attachment, i.e., the boom angle θ1, the arm angle θ2, and the bucket angle θ3. Specifically, the distance D2 is determined according to the swing angle and the boom angle θ1, the arm angle θ2, and the bucket angle θ3, while the distance D3 is determined according to the swing angle and the boom angle θ1. Furthermore, the distance D4 is determined according to the bucket angle θ3, and the distance D5 is determined according to the arm angle θ2.

Therefore, the controller 30 can calculate the maximum allowable pressure PBmax using the rotation angle, the boom angle θ1, and equation (6).

The controller 30 can also suppress the lifting of the excavator 100 by maintaining the pressure PB in the rod-side oil chamber 7R of the boom cylinder 7 at a predetermined pressure that is equal to or lower than the maximum allowable pressure PBmax. Specifically, when the pressure PB reaches the predetermined pressure, the controller 30 increases the flow rate of hydraulic oil flowing out from the rod-side oil chamber 7R to the hydraulic oil tank, thereby lowering the pressure PB. This is because the reduction in pressure PB reduces the arm thrust FA, as shown in equation (4)', and further reduces the excavation reaction force FR and its vertical component FR1, as shown in equation (2)'.

The maximum allowable excavation reaction force FRmax, which is the maximum value of the excavation reaction force that does not cause the machine body to lift up, is expressed by the following formula (7), and the vertical component FR1max of the maximum allowable excavation reaction force FRmax is expressed by the following formula (8). The maximum allowable excavation reaction force FRmax is a force that has the same magnitude as the maximum allowable excavation force and is in the opposite direction to the maximum allowable excavation force.
FRmax=M・g・D1/(D2・cosθ)...(7)
FR1max=M・g・D1/D2...(8)
The position of the rotation center RC is determined based on the output of the turning state sensor S5. For example, when the turning angle, which is the angle between the front-rear axis of the lower traveling body 1 and the front-rear axis of the upper rotating body 3, is 0 degrees, the rear end of the part where the lower traveling body 1 contacts the ground surface (horizontal plane) becomes the rotation center RC, and when the turning angle is 180 degrees, the front end of the part where the lower traveling body 1 contacts the ground surface becomes the rotation center RC. When the turning angle is 90 degrees or 270 degrees, the side end of the part where the lower traveling body 1 contacts the ground surface becomes the rotation center RC.

Next, a process in which the controller 30 assists in an excavation operation (hereinafter, referred to as "assistance process") will be described with reference to Figures 6 and 7. Figure 6 is a flow chart showing an example of the flow of the assistance process. The controller 30 repeatedly executes this assistance process at a predetermined control period while an excavation operation is being performed. Figure 7 is a diagram showing the state in which the excavator 100 executing the assistance process excavates a pile of earth and sand. Specifically, Figure 7 shows the state in which the operator is performing excavation work by operating the left operating lever 26L rearward (in the direction of closing the arm). Note that, for clarity, the boom cylinder 7, arm cylinder 8, and bucket cylinder 9 are omitted from Figure 7.

First, the controller 30 determines whether the excavation force exceeds a predetermined value (step ST1). In the illustrated example, the excavation support unit 56 of the controller 30 determines that the excavation force EF exceeds a predetermined value when the vertical component EF1 of the excavation force EF calculated by the force calculation unit 55 exceeds a predetermined value TH. In the illustrated example, the predetermined value TH is a value obtained by multiplying the value of the vertical component of the maximum allowable excavation force by 0.7.

Figure 7 shows line segment L1 connecting the center of rotation RC, which is the fulcrum when lift-off of the machine body occurs as shown by arrow AR1, to the point of application WP of the excavation force EF, and line segment L2 passing through the point of application WP and perpendicular to line segment L1. Figure 7 also shows the excavation force EF and its vertical component EF1 with block arrows, indicating that the value of the vertical component EF1 exceeds the predetermined value TH by an excess amount EX, and that the value of the vertical component EF1 is below the maximum allowable vertical component UL, which is the vertical component of the maximum allowable excavation force.

If it is determined that the excavation force EF does not exceed the predetermined value (NO in step ST1), the excavation support unit 56 ends the current support process. This is because the machine body will not lift up. In this case, the tip of the bucket 6, which is the point of application of the excavation force, moves along the trajectory L3 shown by the dotted line in Figure 7.

When it is determined that the excavation force EF exceeds the predetermined value (YES in step ST1), the excavation support unit 56 determines the boom raising speed based on the excess (step ST2). In the illustrated example, the excavation support unit 56 determines the boom raising speed so that the boom raising speed increases as the excess increases. In the illustrated example, determining the boom raising speed means determining the opening area of the solenoid valve 31BL (see FIG. 4B) as a boom raising solenoid valve, that is, determining the magnitude of the control command (current command) for the solenoid valve 31BL. Increasing the boom raising speed means increasing the opening area of the solenoid valve 31BL. The opening area of the solenoid valve 31BL may be controlled by open loop control, or may be controlled by closed loop control based on the boom raising side pilot pressure detected by the pilot pressure sensor, the stroke amount of the boom cylinder 7 detected by the stroke sensor, or the boom angle detected by the boom angle sensor S1.

Then, the excavation support unit 56 determines whether the amount of arm operation exceeds a predetermined amount (step ST3). In the illustrated example, the excavation support unit 56 determines that the amount of arm operation exceeds a predetermined amount when the amount of operation (tilt angle) of the left operating lever 26L backward (arm closing direction) exceeds a predetermined amount (predetermined angle).

In addition, instead of determining whether the amount of operation of the left operating lever 26L backward (arm closing direction) exceeds a predetermined amount, the excavation support unit 56 may determine whether the operation speed (operation angle per unit time) of the left operating lever 26L backward (arm closing direction) exceeds a predetermined speed. Then, if the operation speed exceeds the predetermined speed, it may be determined that the amount of arm operation exceeds the predetermined amount.

When it is determined that the arm operation amount exceeds the predetermined amount (YES in step ST3), the excavation support unit 56 corrects the boom raising speed based on the arm operation amount (step ST4). In the illustrated example, the excavation support unit 56 corrects the boom raising speed determined based on the magnitude of the excess so that the application point WP moves along the line segment L1 as shown by the arrow AR2 in FIG. 7. In other words, the excavation support unit 56 corrects the boom raising speed so that the movement speed of the application point WP in a direction parallel to the line segment L2 becomes zero. That is, the excavation support unit 56 corrects the boom raising speed so that the downward movement of the application point WP in a direction parallel to the line segment L2 due to the arm closing operation is canceled by the upward movement of the application point WP in a direction parallel to the line segment L2 due to the boom raising operation.

On the other hand, if it is determined that the arm operation amount does not exceed the predetermined amount (NO in step ST3), the excavation support unit 56 executes the next step, step ST5, without correcting the boom raising speed.

Then, the excavation support unit 56 executes the boom raising operation (step ST5). In the illustrated example, the boom raising operation is executed so as to achieve a boom raising speed determined based on the size of the excess, or a boom raising speed corrected based on the amount of arm operation. That is, the excavation support unit 56 executes the boom raising operation regardless of whether or not the operator is performing a boom raising operation. Note that, when the operator is performing a boom raising operation, the excavation support unit 56 executes the boom raising operation so as to achieve the greater of the boom raising speed determined by the boom raising operation and the boom raising speed derived by the excavation support unit 56.

By executing such support processing, the controller 30 can realize an excavation operation that utilizes an excavation force that can be the maximum allowable excavation force while suppressing floating of the machine body. Therefore, the controller 30 can improve the work efficiency of the excavator 100.

As described above, the excavator 100 according to the embodiment of the present disclosure includes, as shown in FIG. 1, a lower traveling body 1, an upper rotating body 3 rotatably mounted on the lower traveling body 1, an attachment AT including a boom 4, an arm 5, and a bucket 6 attached to the upper rotating body 3, and a controller 30 as a control device that repeatedly calculates the excavation force based on information related to the excavation operation by the attachment AT. As shown in FIG. 7, the controller 30 is configured to raise the boom 4 so that the point of action WP moves toward the fulcrum (center of rotation RC) when the excavation force EF exceeds a predetermined value in order to prevent the lower traveling body 1 from rotating about the fulcrum (center of rotation RC) due to the reaction force of the excavation force EF generated during the arm closing operation and the front end of the upper rotating body 3 from lifting up as shown by the arrow AR1.

With this configuration, the controller 30 can prevent the front end of the upper rotating body 3 from lifting up during excavation operations. In other words, the controller 30 can prevent so-called jacking up from occurring during excavation operations. Therefore, the excavator 100 can perform excavation operations using the maximum allowable excavation force, thereby improving work efficiency.

From another perspective, in the excavator 100 according to the embodiment of the present disclosure, the controller 30 is configured to raise the boom 4 when the excavation force EF generated during the arm closing operation exceeds a predetermined value in order to prevent the lower traveling body 1 from rotating about the fulcrum (center of rotation RC) due to the reaction force of the excavation force EF generated during the arm closing operation and the front end of the upper rotating body 3 from lifting up as shown by the arrow AR1, as shown in Fig. 7. The lifting speed of the boom 4 (boom raising speed) is determined based on the excess, which is the difference between the current value of the excavation force EF and the predetermined value, and is controlled to be larger as the excess increases. In the example shown in Fig. 7, the controller 30 is configured to raise the boom 4 when the vertical component EF1 of the excavation force EF generated during the arm closing operation exceeds a predetermined value TH. The lifting speed of the boom 4 (boom raising speed) is determined based on the excess EX, which is the difference between the current value of the vertical component EF1 of the excavation force EF and a predetermined value TH, and is controlled to be larger the larger the excess EX is.

With this configuration, the controller 30 can prevent the front end of the upper rotating body 3 from lifting up during excavation operations. In other words, the controller 30 can prevent so-called jacking up from occurring during excavation operations. Therefore, the excavator 100 can perform excavation operations using the maximum allowable excavation force, thereby improving work efficiency.

In addition, in the excavator 100, the controller 30 may be configured to control the lifting of the boom 4 by controlling the stroke amount of the boom cylinder 7, the rotation angle of the boom 4, the boom-raising pilot pressure, or the opening area of the solenoid valve 31BL as a boom-raising solenoid valve by open-loop control or closed-loop control, etc., when the excavation force EF exceeds a predetermined value.

This configuration allows the controller 30 to control the boom raising speed with high precision, and more reliably prevents the jacking up from occurring.

In addition, in the excavator 100, when the excavation force EF exceeds a predetermined value and a boom raising operation is being performed, the controller 30 may raise the boom 4 at a raising speed that is greater than the raising speed corresponding to the amount of operation of the boom raising operation.

With this configuration, the controller 30 can prevent jacking up by raising the boom 4 at an appropriate lifting speed, even when the operator of the excavator 100 is performing a combined operation that includes a boom raising operation and an arm closing operation.

In addition, in the excavator 100, when the excavation force EF exceeds a predetermined value, as shown in FIG. 7, the vertical component EF1 of the excavation force EF may exceed a predetermined value TH. The vertical component EF1 is a component in a direction perpendicular to the straight line (line segment L1) connecting the fulcrum (center of rotation RC) and the point of action (tip of the bucket 6).

With this configuration, the controller 30 can determine whether to raise the boom 4 based on the magnitude of the vertical component EF1 of the excavation force EF, which has a significant effect on the occurrence of jacking up. Therefore, the controller 30 can more reliably prevent jacking up from occurring during excavation operations. And the excavator 100 can more reliably perform excavation operations using the maximum allowable excavation force, further improving work efficiency.

The above describes preferred embodiments of the present invention in detail. However, the present invention is not limited to the above-described embodiments, nor to the embodiments described below. Various modifications or substitutions can be applied to the above-described or below-described embodiments without departing from the scope of the present invention. Furthermore, features described separately can be combined as long as no technical contradiction occurs.

For example, the shovel 100 may be a remote-controlled shovel. In this case, the controller 30 may be a control device installed in a remote control room outside the shovel 100. The shovel 100 may also be an autonomous shovel that does not require operation by an operator.

1: Lower traveling body 2: Swing mechanism 2A: Swing hydraulic motor 2M: Travel hydraulic motor 2ML: Left traveling hydraulic motor 2MR: Right traveling hydraulic motor 3: Upper rotating body 4: Boom 5: Arm 6: Bucket 7: Boom cylinder 8: Arm cylinder 9: Bucket cylinder 10: Cabin 11: Engine 13: Regulator 14: Main pump 15: Pilot pump 17: Control valve unit 18L: Left throttle 18R: Right throttle 19L: Left control pressure sensor 19R: Right control pressure sensor 26: Operation device 26D: Travel operation device 26DL: Left travel lever 26DR: Right travel lever 26L: Left operation lever 26R: Right operation lever 28: Discharge pressure sensor 29, 29DL, 29DR, 29LA, 29LB, 29RA, 29RB, ... Operation sensor 30: Controller 31, 31AL to 31FL, 31AR to 31FR... solenoid valve 40... display device 42... input device 42a... mode switch 43... sound output device 47... storage device 50... machine guidance section 51... position calculation section 52... distance calculation section 53... information transmission section 54... automatic control section 55... force calculation section 56... excavation support section 100... shovel 171 to 176... control valve AT... attachment EF... excavation force EF1... vertical component EX... excess Q1... positioning device RC... center of rotation S1... boom angle sensor S2... arm angle sensor S3... bucket angle sensor S4... machine body inclination sensor S5... turning state sensor S6... imaging device S6B, S6F, S6L, S6R... camera S7B... boom bottom pressure sensor S7R... boom rod pressure sensor S8B: Arm bottom pressure sensor S8R: Arm rod pressure sensor S9B: Bucket bottom pressure sensor S9R: Bucket rod pressure sensor T1: Communication device TH: Predetermined value UL: Maximum allowable vertical component WP: Point of action

Claims (6)

A lower running body;
An upper rotating body rotatably mounted on the lower traveling body;
An attachment including a boom, an arm, and a bucket attached to the upper rotating body;
and a control device that repeatedly calculates an excavation force based on information about an excavation operation by the attachment,
The control device raises the boom so that the tip of the bucket moves toward the fulcrum when the excavation force exceeds a predetermined value in order to suppress lifting of the front end of the upper rotating body caused by the lower traveling body rotating about the fulcrum due to a reaction force of the excavation force generated during the arm closing operation.
Shovel. A lower running body;
An upper rotating body rotatably mounted on the lower traveling body;
An attachment including a boom, an arm, and a bucket attached to the upper rotating body;
and a control device that repeatedly calculates a value of the excavation force based on information about the excavation operation of the attachment,
The control device is configured to raise the boom when the excavation force generated during the arm closing operation exceeds a predetermined value in order to suppress the lower traveling body from rotating about a fulcrum due to a reaction force of the excavation force generated during the arm closing operation, and the front end portion of the upper rotating body from lifting up,
The boom raising speed is determined based on the difference between the current value of the excavation force and a predetermined value, and the larger the difference, the larger the boom raising speed.
Shovel. the control device controls the lifting of the boom by controlling a stroke amount of a boom cylinder when the excavation force exceeds a predetermined value.
The shovel according to claim 1 or 2. The control device controls the lifting of the boom by controlling a rotation angle of the boom when the excavation force exceeds a predetermined value.
The shovel according to claim 1 or 2. When the excavation force exceeds a predetermined value and a boom raising operation is being performed, the control device raises the boom at a raising speed that is higher than a raising speed corresponding to an amount of operation of the boom raising operation.
The shovel according to claim 1 or 2. When the excavation force exceeds a predetermined value, the vertical component of the excavation force exceeds a predetermined value;
The vertical component is a component in a direction perpendicular to a straight line connecting the fulcrum and the tip of the bucket.
The shovel according to claim 1 or 2.

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