JP2018105487A - Hydraulic actuation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an appropriate hydraulic pressure supply to each of several hydraulic actuators as required when they are simultaneously operated.SOLUTION: When operation levers 20 for operating any one of first and second hydraulic actuators AG1, AG2 are operated, a first change-over valve 31 is released to allow operation oil to supply from the first control valves 40 to the second control valves 50, a second change-over valve 35 is closed to restrict operation oil supply from the third control valves 60 to the second control valves 50. When operation levers 20 for operating together at least one hydraulic actuator of the first hydraulic actuators AG1 and the second hydraulic actuators AG2 are operated, a first change-over valve 31 is closed to restrict operation oil supply from the first control valves 40 to the second control valves 50, the second change-over valve 35 is released to allow the operation oil supply from the third control valves 60 to the second control valves 50.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a hydraulic actuator having a plurality of hydraulic actuators operated by hydraulic pressure, such as a power shovel.

  The power shovel is configured, for example, by providing a swivel base on a vehicle that can travel so that the swivel can swing horizontally, and by providing a drilling device that includes a boom, an arm, and a bucket. It is well known that the traveling operation of the traveling vehicle, the turning operation of the swivel base, and the swinging operation of the boom, arm, and bucket are operated using hydraulic pressure. That is, the travel operation is performed by the hydraulic travel motor, the swing operation is performed by the hydraulic swing motor, and the swing operation of the boom, the arm, and the bucket is performed by the boom cylinder, the arm cylinder, and the bucket cylinder, which are hydraulic cylinders. Specifically, hydraulic oil from a hydraulic supply source (for example, a hydraulic pump driven by an engine) is supplied to a traveling hydraulic motor or the like via a control valve in accordance with the operation of an operation lever to control the operation of each device. Done. Note that the hydraulic travel motor, the hydraulic swing motor, the boom cylinder, the arm cylinder, and the bucket cylinder are collectively referred to as a hydraulic actuator.

  For example, when the bucket operating lever that swings the bucket is operated, the hydraulic oil supply to the bucket cylinder is controlled by the bucket control valve in response to the operation of the bucket operating lever, and at a speed corresponding to the operation of the bucket operating lever. The bucket cylinder is expanded and contracted, and the bucket is swung. A hydraulic actuator configured by mounting a plurality of hydraulic actuators such as a power shovel usually has a plurality of control valves corresponding to each hydraulic actuator in parallel in a supply oil passage to which hydraulic oil from a hydraulic pump is supplied. (See, for example, FIG. 1 of Patent Document 1).

  When work is performed using the power shovel having such a configuration, a plurality of operations may be performed simultaneously (combined operations) depending on the work situation. For example, there is a case where an operation of simultaneously swinging the boom and the arm is performed while the vehicle is traveling. In this case, it is necessary to supply hydraulic oil to the hydraulic travel motor, the boom cylinder, and the arm cylinder in accordance with this combined operation. However, how to control the supply oil amount when the maximum amount of oil that can be supplied from the hydraulic pump is less than the oil amount required by the hydraulic travel motor, boom cylinder, and arm cylinder according to the operation amount of the operation lever. It is necessary to think about. In view of this, when the lever operation for simultaneously swinging the boom and the arm in addition to the traveling hydraulic motor is performed, the operating speed of the boom and the arm is allowed to be slow, but the traveling operation lever is The applicant of the present application has proposed a hydraulic actuator that enables control that can ensure traveling operation (Patent Document 2).

JP-A-10-103305 JP 2014-20395 A

By the way, in a hydraulic actuator used for a power shovel or the like, a load sensing system using a pressure compensation valve is used for the purpose of minimizing the driving load of the hydraulic pump. The pressure compensation valve is used to increase the supply pressure by reducing the amount of oil supplied to the actuator with a small load during complex operation, and to supply the necessary hydraulic pressure to the actuator with a large load. When this load sensing system is used in the hydraulic actuator disclosed in Patent Document 2, when a combined operation of simultaneously swinging the boom and the arm while running the vehicle is performed, the fluctuation of the operating load of the boom and the arm is changed. As a result, it has been found that there is a possibility that the hydraulic oil supply to the traveling hydraulic motor fluctuates and smooth traveling is hindered. In particular, the operating loads of the boom and the arm may fluctuate greatly, and there is a problem that smooth running is easily hindered when the fluctuation is abrupt and large.

  The present invention has been made in view of the above problems, and a hydraulic actuator having a configuration capable of supplying an appropriate hydraulic pressure as necessary when a plurality of hydraulic actuators are simultaneously operated. The purpose is to provide.

  In order to solve the above problems, a hydraulic actuator according to the present invention comprises first, second, and third hydraulic actuator groups configured to include at least one hydraulic actuator, and the first hydraulic actuator group. A first control valve group comprising at least one control valve for controlling hydraulic oil supply to the hydraulic actuator, and at least one control valve for performing hydraulic oil supply control to the hydraulic actuator constituting the second hydraulic actuator group A second control valve group comprising: a third control valve group comprising at least one control valve for performing hydraulic oil supply control to the hydraulic actuators constituting the third hydraulic actuator group; Operates first and second hydraulic oil supply sources to supply and first to third hydraulic actuator groups Constructed and an operation device which is operated to. Further, the hydraulic actuator connects the first oil passage for supplying the first control valve group with the hydraulic oil from the first hydraulic oil supply source, and connects the first control valve group and the second control valve group. A second oil passage, a third oil passage for supplying hydraulic oil from the second hydraulic oil supply source to the third control valve group, and a fourth connecting the third control valve group and the second control valve group. An oil passage, a first switching valve disposed in the second oil passage, and a second switching valve disposed in the fourth oil passage. When one of the first and second hydraulic actuator groups is operated, the first switching valve is opened to allow hydraulic oil to be supplied from the first control valve group to the second control valve group. And closing the second switching valve to restrict the supply of hydraulic oil from the third control valve group to the second control valve group, and at least one hydraulic actuator of the first hydraulic actuator group and the first When operating at least one hydraulic actuator of the two hydraulic actuator groups together, the first switching valve is closed to restrict the supply of hydraulic oil from the first control valve group to the second control valve group, and The 2 switching valve is opened to allow the hydraulic oil supply from the third control valve group to the second control valve group.

  In the hydraulic actuator configured as described above, preferably, a pilot oil passage to which pilot oil pressure is supplied is provided, and the control valves constituting the first and second control valve groups respectively communicate the pilot oil passage to the drain side. A pilot control unit that performs control to shut off, and each of the pilot control units communicates the pilot oil passage to the drain side when the corresponding control valve is in the neutral position, and the pilot oil in the operation position. The passage is configured to be shut off from the drain side, and the pilot control unit in at least one control valve of the first control valve group and the pilot control unit in at least one control valve of the second control valve group include: When both are shut off from the drain side, pilot oil pressure is generated in the pilot oil passage. Pilot hydraulic is configured to open the second switching valve while closing the first switching valve by acting on the first and the second switching valve via the pilot oil passage.

In the hydraulic actuator configured as described above, it is more preferable that the control valves constituting the first and second control valve groups each include a load pressure of a corresponding hydraulic actuator controlled by its own control valve, and the first and second control valves. There is provided a pressure compensation valve that operates in response to the maximum load pressure among the load pressures of the hydraulic actuators constituting the second hydraulic actuator group, and the first switching valve is closed to close the first control valve group. When the hydraulic oil supply to the second control valve group is restricted from being performed, the pressure compensation valve provided in the first control valve group includes a maximum load pressure of the hydraulic actuators constituting the two hydraulic actuator groups. It is configured not to act.

  According to the hydraulic actuator according to the present invention, when any one of the first and second hydraulic actuator groups is operated, the first switching valve is opened and the operation from the first control valve group to the second control valve group is performed. Since the oil supply is allowed and the hydraulic oil supply from the third control valve group to the second control valve group is restricted by closing the second switching valve, the operation of the corresponding control valve according to the operation of the operating device Is controlled, the hydraulic oil supplied from the first hydraulic oil supply source is supplied to the corresponding hydraulic actuator, and the operation thereof is appropriately controlled. On the other hand, when operating at least one hydraulic actuator of the first hydraulic actuator group and at least one hydraulic actuator of the second hydraulic actuator group together, the first switching valve is closed to change the second control valve from the first control valve group. The supply of hydraulic oil to the group is restricted, and the second switching valve is opened to allow the supply of hydraulic oil from the third control valve group to the second control valve group. For this reason, the hydraulic oil is supplied from the first hydraulic oil supply source to the first control valve group, and the hydraulic oil supply to the first hydraulic actuator group is controlled by the first control valve group, and the operation thereof is accurately controlled. The On the other hand, since the hydraulic oil is supplied from the second hydraulic oil supply source to the second control valve group through the fourth control passage through the third control valve group, the second hydraulic actuator group is supplied by the second control valve group. The hydraulic fluid supply to the hydraulic actuator is controlled, and the operation of the hydraulic actuators on these sides is also appropriately controlled independently of the first hydraulic actuator group.

  In the above-described hydraulic actuator, the control valves constituting the first and second control valve groups are each provided with a pilot control unit that performs control for communicating / blocking the pilot oil passage to the drain side, When the corresponding control valve is in the neutral position, the pilot oil passage is communicated with the drain side, and when the corresponding control valve is in the operating position, the pilot oil passage is shut off from the drain side. Pilot control of the first and second control valve groups It is preferable that the pilot hydraulic pressure generated when both parts are shut off from the drain side is applied to the first and second switching valves to close the first switching valve and open the second switching valve. If it does in this way, the 1st and 2nd change-over valve can be operated appropriately corresponding to the operation of the 1st and 2nd hydraulic actuator groups.

  Further, in the hydraulic actuator described above, a pressure compensation valve is provided in each of the control valves constituting the first and second control valve groups, the first switching valve is closed, and the second control valve is switched from the first control valve group. When the hydraulic oil supply to the group is restricted, the pressure compensation valve provided in the first control valve group is configured not to act on the maximum load pressure of the hydraulic actuator constituting the second hydraulic actuator group. Is preferred. In this way, when any one of the first hydraulic actuator group and the second hydraulic actuator group is controlled by the hydraulic fluid supplied from the first hydraulic fluid supply source, the pressure of the control valve for performing the operational control is naturally. Compensation valve works properly. Further, the operation control of the first hydraulic actuator group is performed by the hydraulic oil supply from the first hydraulic oil supply source, and the operation control of the second hydraulic actuator group is performed by the hydraulic oil supply from the second hydraulic oil supply source. Each pressure compensation valve can be operated properly without the mutual hydraulic actuator group being affected by the change in hydraulic pressure of the counterpart hydraulic actuator group.

It is a perspective view which shows the power shovel comprised mounting the hydraulic actuator which concerns on this invention. It is a block diagram which shows the control system of the said power shovel. It is a hydraulic circuit diagram which shows the structure of the hydraulic actuator of the said power shovel.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a crawler type excavator 1 to which the present invention is applied, and FIG. 2 is a block diagram showing a control system for controlling the operation of the hydraulic actuator of the power shovel 1. The schematic configuration of the power shovel 1 will be described first with reference to FIGS. 1 and 2. In addition, since the swivel base 6 turns and the front-back direction changes, for convenience of explanation, the arrow directions shown in FIG. 1 will be defined as front-back, left-right, and up-down.

  As shown in FIG. 1, the excavator 1 includes a traveling device 4 configured to include traveling mechanisms 3 and 3 on the left and right sides of a traveling carriage 2 having a substantially H shape in plan view. A blade 5 is provided at the rear part of the traveling carriage 2 so as to be swingable up and down, a swivel base 6 is provided at the upper part of the traveling carriage 2 so as to be pivotable horizontally, and an excavator mechanism 7 is provided at the front part of the swivel base 6 to turn An operator cabin 8 for boarding the operator is erected on the top of the table 6.

  The pair of left and right traveling mechanisms 3, 3 includes a driving sprocket wheel 9 provided at the left and right front portions of the traveling carriage 2, an idler wheel 10 provided at the left and right rear portions of the traveling carriage 2, a driving sprocket wheel 9 and an idler. The crawler belt 11 is wound around the wheel 10. The traveling mechanism 3 provided on the right side of the traveling carriage 2 is provided with a hydraulically driven right traveling motor 9R that drives the driving sprocket wheel 9. The traveling mechanism 3 provided on the left side of the traveling carriage 2 includes Is provided with a hydraulically driven left travel motor 9L. The blade 5 is swung up and down by a hydraulically driven blade cylinder 26 (see FIG. 2). The swivel base 6 is horizontally swiveled with respect to the traveling device 4 by a hydraulically driven swivel motor 25 (see FIG. 2).

  As shown in FIG. 1, the excavator mechanism 7 includes a boom 12 pivotally connected to the front portion of the swivel base 6, and can swing up and down within the swing surface of the boom 12 at the tip of the boom 12. And an bucket 13 pivotally connected to the tip of the arm 13 so as to be swingable up and down. A hydraulically driven boom cylinder 15 is provided across the front portion of the swivel base 6 and the boom 12, and the boom 12 is oscillated by the boom cylinder 15. A hydraulically driven arm cylinder 16 is provided across the boom 12 and the arm 13, and the arm 13 is pivoted by the arm cylinder 16. A hydraulically driven bucket cylinder 17 is provided across the arm 13 and the bucket 14, and the bucket 14 is oscillated by the bucket cylinder 17.

  The operator cabin 8 is formed in a substantially rectangular box shape, and an operator seat 18 on which an operator sits facing forward is provided. On the left and right sides of the operator seat 18 are provided a right work operation lever 21 and a left work operation lever 22 for operating the blade 5, the swivel base 6, the shovel mechanism 7, and the like. A right travel operation lever 23 and a left travel operation lever 24 for operating the travel device 4 are provided in front of the operator seat 18. The right travel operation lever 23 is an operation lever for operating the right travel motor 9R, and the left travel operation lever 24 is an operation lever for operating the left travel motor 9L. These four operation levers 21 to 24 are collectively referred to as an operation lever 20.

In the power shovel 1 configured as described above, an operator sits on the operator seat 18 and tilts the right work operation lever 21 and the left work operation lever 22 back and forth, and right and left, and the right travel operation lever 23 and the left travel lever. By tilting the operation lever 24 back and forth, the power shovel 1 can be moved back and forth by the travel device 4, or the excavator mechanism 7 can be operated to perform work such as excavation.

  Specifically, the boom 12 is swung up and down by tilting the right operation lever 21 back and forth, and the bucket 14 is swung up and down by tilting left and right. The left work operation lever 22 is tilted back and forth to swing the arm 13 up and down and swing left and right to swing the swivel 6 to the left and right. Further, the right traveling operation lever 23 is tilted forward to drive the right traveling motor 9R in the forward direction, the right traveling mechanism 3 is driven in the forward direction, and the backward traveling is performed by tilting in the backward direction. To drive backwards. Similarly, the left traveling motor 9L is forwardly driven by tilting the left traveling operation lever 24 in the forward direction to drive the left traveling mechanism 3 in the forward direction, and the backward traveling is driven by tilting in the backward direction. And drive in the reverse direction.

  The configuration of the power shovel 1 has been described so far. Next, in the power shovel 1, a configuration of a hydraulic control unit HCU that operates hydraulic actuators such as the boom cylinder 15 in order to perform the above-described operation in accordance with the operation of the operation levers 21 to 24 will be described. 2 and FIG. In addition, when each operation lever 21-24 is operated back and forth or right and left as described above, an operation signal (electric signal or signal hydraulic pressure) corresponding to the operation direction and operation amount is output.

  As shown in FIG. 2, the hydraulic control unit HCU has a control device 30 to which operation signals from the operation levers 21 to 24 (operation levers 20) are input, and is controlled by the control device 30 to operate the hydraulic actuator. A first control valve group 40, a second control valve group 50, and a third control valve group 60 that perform oil supply control are provided. The first control valve group 40 includes right and left travel control valves 41 and 45 that control the supply of hydraulic oil to the left and right travel motors 9R and 9L. These right and left travel control valves 41 and 45 are hydraulic pilot type valves, and the right and left travel control valves are used to control the travel control pilot pressure from the control device 30 in response to the operation of the right and left travel operation levers 23 and 24. The pilot ports 41 and 45 are supplied to control their operation. This operation control will be described later. The left and right traveling motors 9R, 9L (hydraulic actuators) that are controlled by the first control valve group 40 are collectively referred to as a first hydraulic actuator group AG1.

  The second control valve group 50 includes a boom control valve 51 that performs hydraulic oil supply control to the boom cylinder 15, an arm control valve 55 that performs hydraulic oil supply control to the arm cylinder 16, and hydraulic oil supply control to the bucket cylinder 17. A bucket control valve 56 is provided. The operation control pilot pressure is supplied from the control device 30 to the pilot ports of these control valves 51, 55, 56 in response to the operation of the right and left work operation levers 21, 22, and the operation thereof is controlled. This operation control will also be described later. The boom cylinder 15, the arm cylinder 16, and the bucket cylinder 17 (hydraulic actuator) that are controlled by the second control valve group 50 are collectively referred to as a second hydraulic actuator group AG2.

The third control valve group 60 includes a swing control valve 61 that controls hydraulic oil supply to the swing motor 25, a blade control valve 65 that controls hydraulic oil supply to the blade cylinder 26, and a service port (external hydraulic pressure take-out port). ) AUX control valve 66 for controlling hydraulic oil supply to 27 is provided. The service port 27 is a hydraulic port for connecting the pipes from the outside and taking out the hydraulic pressure to the outside. For example, when the hydraulic operation attachment is attached, the service port 27 is a port for supplying hydraulic oil to the hydraulic actuator that operates the attachment. It is. The operation control of these control valves 61, 65, 66 is performed by operating an operating device (not shown). When an operation device (not shown) is operated, an operation signal is input to the control device 30, and an operation control pilot pressure is supplied from the control device 30 to the pilot ports of the control valves 61, 65, 66 in response to the operation of the operation device (not shown). To control its operation. This operation control will also be described later. The swing motor 25, the blade cylinder 26, and the service port 27 that are controlled by the third control valve group 60 (hydraulic supply control) are collectively referred to as a third hydraulic actuator group AG3.

  The hydraulic control unit HCU further includes a first hydraulic pump P1, a second hydraulic pump P2, and a pilot hydraulic pump P3 that are rotationally driven by the engine E. The oil discharged from the first hydraulic pump P1 is sent to the first control valve group 40 through the oil passage 71. The oil discharged from the second hydraulic pump P2 is sent to the third control valve group 60 through the oil passage 81. The third pump P3 is a pump for supplying a pilot pressure. The discharged oil is discharged to the oil passage 91, and the pilot pressure regulating valve 92 generates the pilot pressure Pp in the oil passage 91.

  The first control valve group 40 and the second control valve group 50 are connected via oil passages 73 and 74. A first switching valve 31 is provided between the oil passages 73 and 74, and the first switching valve 31 is configured to perform communication / blocking control between the first control valve group 40 and the second control valve group 50. ing. Further, the second control valve group 50 and the third control valve group 60 are connected via oil passages 83 and 84. A second switching valve 35 is provided between the oil passages 83, 84, and the second switching valve 35 is configured to perform communication / blocking control between the second control valve group 50 and the third control valve group 60. ing.

  Hereinafter, the detailed configuration of the hydraulic control unit HCU will be described with reference to FIG. 3 and the operation control of the first to third hydraulic actuator groups AG1 to AG3 based on the operation of the operation lever 20 will be described.

  The first hydraulic pump P <b> 1 is a swash plate type variable displacement hydraulic pump, is driven to rotate by the engine E, sucks up the hydraulic oil stored in the hydraulic oil tank T, and discharges it to the oil passage 71. The inclination angle of the swash plate in the first hydraulic pump P1 is set so that the amount of hydraulic oil supplied to the hydraulic actuator is maintained in response to the operation of the operation lever 20 regardless of the fluctuation of the load pressure in the hydraulic actuator. It is controlled by a pump regulator (not shown). The pump regulator includes a discharge hydraulic pressure of the first hydraulic pump P1 (the hydraulic pressure of the oil passage 71, which is referred to as a pump pressure) and a highest load pressure (hydraulic actuator operated by using the discharged oil ( Maximum load pressure) is input. Based on these input pressures, the pump regulator controls the discharge amount by controlling the swash plate angle of the first hydraulic pump P1 so that the pump pressure is higher than the maximum load pressure by a predetermined pressure ( So-called “load sensing control”). The second hydraulic pump P2 is a swash plate type fixed displacement type hydraulic pump, and is configured to be open center controlled.

  The third hydraulic pump P3 is a fixed displacement type hydraulic pump, is driven to rotate by the engine E, sucks up the hydraulic oil stored in the hydraulic oil tank T, and discharges it to the pilot oil passage 91. As described above, the hydraulic pressure in the pilot oil passage 91 is adjusted to the pilot pressure Pp by the pilot pressure adjusting valve 92. The pilot pressure Pp is sent to the control device 30 via the oil passage 93, and from here, the target control valves (first, second and third control valve groups 40, 50, 60) according to the operation of the operation lever 20. Is supplied to the pilot port of the target control valve), and the operation of this control valve is controlled. The pilot oil passage 91 is also connected to the pilot oil passage 95 via a throttle 94, which will be described later.

The oil passage 71 that receives the oil discharged from the first hydraulic pump P1 is connected to the right travel control valve 41 from the oil passage 71a as shown in FIG. The right travel control valve 41 is subjected to load sensing control, and when neutral, the oil passage 71 is sent from the oil passage 72 to the left travel control valve 45 (not shown in FIG. 3). A pressure compensation valve 43 is provided on the inlet side of the right travel control valve 41. Pilot ports 44a and 44b are provided at the upper and lower ends of the right travel control valve 41, and are controlled by the control device 30 according to the operation of the right travel operation lever 23 to be supplied with the pilot pressure Pp. The operation of the control valve 41 is controlled. Specifically, the hydraulic oil supplied from the first pump P1 to the oil passage 71 is controlled by the right travel control valve 41 and supplied to the right travel motor 9R. As a result, the right travel motor 9R is supplied with hydraulic oil in the supply direction and supply amount according to the operation of the right travel operation lever 23. As a result, the right travel motor 9R is rotationally driven at a rotation direction and a rotation speed corresponding to the operation direction and the operation amount of the right travel operation lever 23.

  The right travel control valve 41 further includes a pilot control unit 42. The inlet side port of the pilot control unit 42 is connected to the oil passage 97a connected to the pilot oil passage 95 described above, and the outlet side port is connected to the tank T via the oil passage 97b. When the right travel control valve 41 is in the neutral position, the pilot control unit 42 connects the inlet side port and the outlet side port, and connects the pilot oil passages 95, 97, and 97a to the tank T (drain side). On the other hand, when the right travel control valve 41 is in the operating position (position moved to the upper side or the lower side in the figure), the pilot control unit 42 shuts off the inlet side port and the outlet side port and opens the pilot oil passages 95, 97, 97a. Shut off from tank T (drain side).

  Although not shown in FIG. 3, the left travel control valve 45 is connected to the oil passage 72. When the left travel control valve 45 is neutral, the oil supplied to the oil passage 72 is sent to the oil passage 73. A pressure compensation valve is also provided on the inlet side of the left travel control valve 45. Pilot ports are also provided at the upper and lower ends of the left travel control valve 45, and a pilot pressure Pp controlled by the control device 30 according to the operation of the left travel operation lever 24 is supplied to the left travel control valve 45. Is controlled. As a result, the hydraulic oil supplied to the oil passage 72 is controlled by the left travel control valve 45 and supplied to the left travel motor 9L. The left travel motor 9L corresponds to the operation direction and the operation amount of the left travel operation lever 24. It is rotationally driven in the rotational direction and rotational speed.

  The left travel control valve 45 further includes a pilot control unit, the pilot oil passage 97 is connected to the inlet side port, and the outlet side port is connected to the oil passage 97a. When the left travel control valve 45 is in the neutral position, the pilot control unit communicates the inlet side port and the outlet side port, and the pilot oil passage 97 is connected to the tank T via the pilot control unit 42 of the right travel control valve 41. Connect to (drain side). When the left travel control valve 45 is in the operating position, the pilot control unit shuts off the inlet side port and the outlet side port, and shuts off the pilot oil passages 95 and 97 from the tank T (drain side).

  As can be seen from the above description, the right travel control valve 41 and the left travel control valve 45 are connected in parallel to the oil passage 71 that receives the oil discharged from the first hydraulic pump P1. That is, the first control valve group 40 is connected to the oil passage 71. In the pilot oil passage extending from the pilot oil passage 95 to the drain side (tank T) via the pilot oil passages 97, 97a, 97b, two pilot control units provided in the right and left travel control valves 41, 45 are connected in series. It leads to. For this reason, when both of these two pilot control units are opened, the pilot oil passage 95 is connected to the drain side, and when at least one of them is closed, the pilot oil passage 95 is blocked from the drain side.

The oil passage 73 is connected to the oil passage 74 via the first switching valve 31, and the oil passage 74 is connected from the oil passage 74 a to the inlet side of the boom control valve 51 through the pressure compensation valve 53. The first switching valve 31 has a pilot port 32 connected to a pilot oil passage 95 via a pilot oil passage 99 on one end side, and a spring 33 on the other end side. When the pressure in the pilot oil passage 95 is low and a low (or zero pressure) pilot pressure is acting on the pilot port 32, the first switching valve 31 is pressed by the spring 33 to the open state shown in the figure, Road 73 and oil path 74
To communicate with. On the other hand, when the pilot pressure Pp is generated in the pilot oil passage 95, the pilot pressure Pp acts on the pilot port 32 through the pilot oil passage 99, and the first switching valve 31 is moved up against the bias of the spring 33. To close the oil passage 73 and the oil passage 74.

  The boom control valve 51 supplies the hydraulic oil in the oil passage 74 to the oil passage 75 as it is when neutral. A pressure compensation valve 53 is provided on the inlet side of the boom control valve 51. Pilot ports 54 a and 54 b are provided at the upper and lower ends of the boom control valve 51, and the pilot pressure Pp is supplied by being controlled by the control device 30 in accordance with the front / rear operation of the right work operation lever 21. The operation of the valve 51 is controlled. Specifically, the hydraulic oil supplied from the first pump P1 to the oil passage 71 bypasses the neutral first control valve group AG1 and is supplied to the boom control valve 51, and is controlled by the boom control valve 51. Is supplied to the boom cylinder 15. As a result, the boom cylinder 15 is supplied with hydraulic oil in the supply direction and the supply amount corresponding to the front / rear operation of the right work operation lever 21. As a result, the boom cylinder 15 is operated at an operation direction and an operation speed corresponding to the operation direction and operation amount of the right work operation lever 21.

  The boom control valve 51 further includes a pilot control unit 52. An oil passage 98 connected to the pilot oil passage 95 described above is connected to the inlet side port of the pilot control unit 52, and the outlet side port is connected to the tank T via the oil passages 98a and 98b. When the boom control valve 51 is in the neutral position, the pilot control unit 52 connects the inlet side port and the outlet side port, and connects the pilot oil passages 95 and 98 to the tank T (drain side). On the other hand, when the boom control valve 51 is in the operating position (position moved to the upper side or the lower side in the figure), the pilot control unit 52 shuts off the inlet side port and the outlet side port and connects the pilot oil passages 95 and 98 to the tank T ( Shut off from the drain side).

  Although not shown in FIG. 3, the arm control valve 55 is connected to the oil passage 75. When the arm control valve 55 is neutral, the hydraulic oil in the oil passage 75 is sent to the oil passage 76 as it is. The oil passage 76 communicates with a tank (drain side) via an unload valve 78. A pressure compensation valve is also provided on the inlet side of the arm control valve 55. Pilot ports are also provided at the upper and lower ends of the arm control valve 55, and a pilot pressure Pp controlled by the control device 30 according to the front / rear operation of the left work operation lever 22 is supplied to the arm control valve 55. Operation is controlled. As a result, the hydraulic oil supplied to the oil passage 75 is controlled by the arm control valve 55 and supplied to the arm cylinder 16, and the arm cylinder 16 has an operation direction corresponding to the operation direction and the operation amount of the left work operation lever 22. Operated at operating speed.

  The arm control valve 55 further includes a pilot control unit, the pilot oil passage 98a is connected to the inlet side port, and the outlet side port is connected to the oil passage 98b. When the arm control valve 55 is in the neutral position, the pilot control unit causes the inlet side port and the outlet side port to communicate with each other, and the pilot oil passage 98a is connected to the tank T (drain) via the pilot control unit 52 of the arm control valve 55. Side). When the arm control valve 55 is in the operating position, the pilot control unit shuts off the inlet side port and the outlet side port, and shuts off the pilot oil passages 95 and 98 from the tank T (drain side).

Although not shown in FIG. 3, the bucket control valve 56 is connected to the oil passage 75. A pressure compensation valve is also provided on the inlet side of the bucket control valve 56. Pilot ports are also provided at the upper and lower ends of the bucket control valve 56, and a pilot pressure Pp controlled by the control device 30 in response to the right / left tilting operation of the right work operation lever 21 is supplied to the bucket control valve 56. Is controlled. As a result, the hydraulic oil supplied from the oil passage 75 is controlled by the bucket control valve 56 and supplied to the bucket cylinder 17. The bucket cylinder 17 has an operation direction corresponding to the operation direction and the operation amount of the right work operation lever 21. Operated at operating speed.

  The bucket control valve 56 further includes a pilot control unit, and a pilot oil passage 98a is connected to an inlet side port of the bucket control valve 56 via a pilot control unit of the arm control valve 55, and an outlet side port is connected to the oil passage 98b. When the bucket control valve 56 is in the neutral position, the pilot control unit communicates the inlet side port and the outlet side port, and connects the pilot oil passage 98a to the tank T (drain side). When the bucket control valve 56 is in the operating position, the pilot control unit shuts off the inlet side port and the outlet side port, and shuts off the pilot oil passages 95 and 98 from the tank T (drain side).

  As can be seen from the above description, a load sensing type boom control valve 51, arm control valve 55, and bucket control valve 56 are connected in parallel to the oil passage 74. That is, the second control valve group 50 is connected to the oil passage 74. In the pilot oil passage extending from the pilot oil passage 95 to the drain side (tank T) via the pilot oil passages 98, 98a, 98b, three boom control valves 51, an arm control valve 55, and a bucket control valve 56 are provided. The pilot control unit is connected in series. For this reason, when all three pilot control units are opened, the pilot oil passage 95 is connected to the drain side, and when at least one of them is closed, the pilot oil passage 95 is blocked from the drain side.

  Next, the oil passage 81 that receives the oil discharged from the second hydraulic pump P2 is connected to the turning control valve 61 as shown in FIG. The turning control valve 61 is an open center type, and when in the neutral state, the oil path 81 on the inlet side is directly communicated with the oil path 82 on the outlet side. Pilot ports 64a and 64b are provided at the upper and lower end portions of the turning control valve 61. Here, pilot pressure Pp is supplied by being controlled by the control device 30 in accordance with the left / right tilting operation of the left work operation lever 22, and turning. The operation of the control valve 61 is controlled. Specifically, the hydraulic oil supplied from the second pump P <b> 2 to the oil passage 81 is supplied to the turning control valve 61, controlled by the turning control valve 61, and supplied to the turning motor 25. As a result, the turning motor 25 is supplied with hydraulic oil in the supply direction and supply amount corresponding to the left / right tilting operation of the left work operation lever 22. As a result, the turning motor 25 is rotationally driven at a rotation direction and a rotation speed corresponding to the operation direction and the operation amount of the left work operation lever 22.

  Although not shown in FIG. 3, the blade control valve 65 is connected to the oil passage 82 on the outlet side of the turning control valve 61. The blade control valve 65 is also of an open center type, and in the neutral state, the oil path 82 on the inlet side is directly communicated with the oil path on the outlet side. Pilot ports are also provided at the upper and lower ends of the blade control valve 65, and a pilot pressure Pp controlled by the control device 30 is supplied in response to an operation of a blade operation lever (not shown) to operate the blade control valve 65. Is controlled. As a result, the hydraulic oil supplied to the oil passage 82 is controlled by the blade control valve 65 and supplied to the blade cylinder 26. The blade cylinder 26 operates in accordance with the operation direction and the operation speed of the blade operation lever. Operated with.

Although not shown in FIG. 3, an AUX control valve 66 is connected to the oil passage on the outlet side of the blade control valve 65. The AUX control valve 66 is also of an open center type, and in the neutral state, the oil path on the inlet side is directly communicated with the oil path on the outlet side. Pilot ports are also provided at the upper and lower end portions of the AUX control valve 66, and a pilot pressure Pp controlled by the control device 30 is supplied in response to an operation of an AUX operation lever (not shown) to operate the AUX control valve 66. Is controlled. As a result, the hydraulic oil supplied from the oil passage 82 through the turning control valve 61 and the blade control valve 65 is controlled by the AUX control valve 66 and supplied to the service port 27. Therefore, the supply of hydraulic oil to the external actuator attached to the service port 27 can be controlled by the AUX control valve 66.

  As can be seen from the above description, the oil path 81 is connected in series with an open center type turning control valve 61, a blade control valve 65, and an AUX control valve 66. That is, the third control valve group 60 is connected to the oil passage 81.

  As described above, the third control valve group 60 having the above configuration is connected to the second control valve group 50 via the oil passages 83 and 84 having the second switching valve 35. This configuration will be described with reference to FIG. 3. The oil passage 83 is connected to the outlet side of the AUX control valve 66 constituting the third control valve group 60, and the second switching valve 35 is connected to the oil passage 83. The second switching valve 35 has a pilot port 36 connected to the pilot oil passage 95 via a pilot oil passage 96 on one end side, and a spring 37 on the other end side. When the pressure in the pilot oil passage 95 is low and a low (or zero pressure) pilot pressure is applied to the pilot port 36, the second switching valve 35 is pressed by the spring 37 to be in the open state shown in the figure, and the oil The passage 83 is communicated with the oil passage 85 to communicate with the drain side (tank T), and the oil passage 84 is closed. On the other hand, when the pilot pressure Pp is generated in the pilot oil passage 95, the pilot pressure Pp acts on the pilot port 36 through the pilot oil passage 96, and the second switching valve 35 is moved downward against the bias of the spring 37. The oil passage 83 and the oil passage 84 are communicated.

  The configuration of the hydraulic control unit HCU has been described above. Before describing the operation, the pressure compensation valve and load sensing control provided in each control valve will be described. The pressure compensation valve has a desired hydraulic fluid even if a load fluctuation (hydraulic fluctuation) of a target hydraulic actuator, which is controlled by the target control valve, is supplied to the control valve (referred to as a target control valve) provided with the pressure compensation valve. This is a valve for making supply. For this reason, the pressure compensation valve sets the passing oil amount so that the input pressure of the target control valve is higher than the operating hydraulic pressure of the target hydraulic actuator by a predetermined pressure.

  Although this is a basic function, desired hydraulic oil is supplied to all of the target control valves even during a combined operation in which a plurality of hydraulic actuators are simultaneously operated. For this reason, the maximum load oil pressure of all the hydraulic actuators is taken out and used as a signal pressure for all the pressure compensation valves to operate the pressure compensation valves. That is, when a combined operation is performed, the maximum load pressure is extracted from the load pressures of a plurality of hydraulic actuators controlled by a plurality of target control valves (using a shuttle valve or the like), and is obtained for each pressure. By acting on the compensation valve, the pressure compensation valve is operated so that the input pressure is higher than the maximum load pressure by a predetermined pressure. Specifically, in a light load control valve, the pressure compensation valve is closed to limit the inflow amount.

  This maximum load pressure is also supplied to a pump regulator that performs variable displacement control (swash plate angle control) of the hydraulic pump to perform load sensing control. As can be seen from the above, the pressure compensation valve provided on the inlet side of each control valve performs pressure compensation for the load of the hydraulic actuator controlled by each control valve. Pressure compensation for maximum load oil pressure is performed. Furthermore, the maximum load pressure is also used for the pump regulator, and load sensing control for performing variable displacement control of the pump using the maximum load pressure is also performed together.

Next, the operation of the hydraulic control unit HCU with respect to the operation of the operation lever 20 will be described. First, a case where the operation of a single hydraulic actuator group is controlled by operation of the operation lever 20 will be described. For example, the operation when only the operation control of the first hydraulic actuator group AG1 by the first control valve group 40 is performed will be described. The first control valve group 40 includes right and left travel control valves 41 and 45, which are operated by operating the right and left travel operation levers 23 and 24, and control hydraulic oil supply to the right and left travel motors 9R and 9L. To do. When at least one of the right and left travel control valves 41 and 45 is operated as described above, the pilot oil passage 97 is shut off from the drain side by the pilot control unit provided in them. However, since the second control valve group 50 is not actuated and is in the neutral position, the pilot oil passage 98 communicates with the drain side by these pilot control units. For this reason, the oil pressure of the pilot oil passage 95 is low, the first switching valve 31 is in the state shown in FIG. 3, and the oil passage 73 and the oil passage 74 are in communication with each other. Since the pilot oil passage 93 connected to the control device 30 is connected to the pilot oil passage 95 via the throttle 94, the pilot pressure Pp is maintained in the pilot oil passage 93, and the pilot pressure Pp is always kept in the control device 30. Is supplied.

  At this time, the pressure compensation valve provided on the inlet side of the right and left travel control valves 41, 45 is a pressure based on the higher pressure (maximum load pressure) of the load pressures of the right and left travel motors 9R, 9L. Compensate. The maximum load pressure is determined by the load pressure of the second hydraulic actuator group AG2 as well, but since the second hydraulic actuator group AG2 is not operated, the highest load pressure of the right and left traveling motors 9R, 9L is high. One of the pressures is the maximum load pressure. The maximum load pressure is also sent to the pump regulator of the first hydraulic pump P1, and pump displacement control based on the maximum load pressure, that is, load sensing control is performed.

  Next, the operation when only the operation control of the second hydraulic actuator group AG2 by the second control valve group 50 is performed will be described. The second control valve group 50 includes a boom control valve 51, an arm control valve 55, and a bucket control valve 56. The second control valve group 50 is operated by operating the right and left work operation levers 21 and 22, and the boom cylinder 15, the arm cylinder 16, and the bucket cylinder. The hydraulic oil supply to 17 is controlled. When at least one of the boom control valve 51, the arm control valve 55, and the bucket control valve 56 is operated, the pilot oil passage 98 is shut off from the drain side by a pilot control unit provided therein. However, since the first control valve group 40 is not operated and is in the neutral position, the pilot oil passage 97 communicates with the drain side by the pilot control unit. For this reason, the oil pressure of the pilot oil passage 95 is low, the first switching valve 31 is in the state shown in FIG. 3, and the oil passage 73 and the oil passage 74 are in communication with each other.

  At this time, the pressure compensation valve provided on the inlet side of the boom control valve 51, the arm control valve 55, and the bucket control valve 56 is the higher pressure of the load pressures of the boom cylinder 15, the arm cylinder 16, and the bucket cylinder 17. Compensates for pressure based on (maximum load pressure). The maximum load pressure is also sent to the pump regulator of the first hydraulic pump P1, and pump displacement control based on the maximum load pressure, that is, load sensing control is performed.

  As described above, when the first hydraulic actuator group AG1 or the second hydraulic actuator group AG2 is operated alone, the hydraulic fluid supplied from the first hydraulic pump P1 is supplied to the first control valve group 40 or the second control valve. It is controlled by the valve group 50 and supplied to the first hydraulic actuator group AG1 or the second hydraulic actuator group AG2.

Next, a case where the first and second hydraulic actuator groups AG1, AG2 are operated simultaneously (for example, a case where the shovel mechanism 7 is operated during traveling) will be described. This is a case where the work operation levers 21 and 22 are also operated while operating the traveling operation levers 23 and 24. At least one of the control valves of the first control valve group 40 and at least one of the second control valve group 50 is used. The control valve is activated. Then, the pilot control unit of any control valve of the first control valve group 40 blocks the pilot oil passage 97 from the drain side, and the pilot control unit of any control valve of the second control valve group 50 is the pilot oil passage. 98 is shut off from the drain side. As a result, a pilot pressure Pp regulated by the pilot pressure regulating valve 92 is generated in the pilot oil passage 95. The pilot pressure Pp acts on the first switching valve 31 via the pilot oil passage 99 and moves it upward to block communication between the oil passage 73 and the oil passage 74. The pilot pressure Pp further acts on the second switching valve 35 via the pilot oil passage 96 and moves it downward, causing the oil passage 83 and the oil passage 84 to communicate with each other.

  Since the first and second switching valves 31 and 35 are thus operated, the discharge oil from the first hydraulic pump P1 is sent from the oil passage 71 to the first control valve group 40, and the operation control of the first hydraulic actuator group AG1 is performed. However, the oil discharged from the first hydraulic pump P1 is not sent to the second control valve group 50. However, the oil discharged from the second hydraulic pump P2 passes through the third control valve group 60 and is sent to the oil path 74 via the oil path 83, the second switching valve 35, and the oil path 84, and is supplied to the second control valve group 50. Sent. For this reason, the second control valve group 50 performs control to supply the oil discharged from the second hydraulic pump P2 to the second hydraulic actuator group AG2, and the operation of the second hydraulic actuator group AG2 is controlled. As a result, the first hydraulic actuator group AG1 is operated by the hydraulic oil from the first hydraulic pump P1, and the second hydraulic actuator group AG2 is operated by the hydraulic oil from the second hydraulic pump P2. The two hydraulic actuator groups AG1, AG2 can be reliably controlled.

  By the way, as described above, each pressure compensation valve arranged on the inlet side of the first and second control valve groups 40, 50 is pressure compensated based on the maximum load pressure of the first and second hydraulic actuator groups AG1, AG2. The load sensing control of the first hydraulic pump P1 is performed based on this maximum load pressure. When this control is performed also when the first hydraulic actuator group AG1 is operated by the hydraulic oil from the first hydraulic pump P1, and the second hydraulic actuator group AG2 is operated by the hydraulic oil from the second hydraulic pump P2, The load fluctuation of the second hydraulic actuator group AG2 adversely affects the operation of the first control valve group 40. Therefore, the maximum load pressure of the second hydraulic actuator group AG2 is not allowed to act on the pressure compensation valve of the first control valve group 40, and is not used for the load sensing control of the first hydraulic pump P1. A three-switching valve (not shown) is provided.

  The third switching valve operates in response to the pilot hydraulic pressure Pp generated in the oil passage 95, and prevents the maximum load pressure of the second hydraulic actuator group AG2 from acting on the pressure compensation valve of the first control valve group 40. In this configuration, the first hydraulic pump P1 is prevented from acting on a pump regulator that performs load sensing control. As a result, each pressure compensation valve arranged on the inlet side of the first control valve group 40 performs pressure compensation based only on the maximum load pressure of the first hydraulic actuator group AG1, and the first pressure control valve group 40 performs the first compensation based on the maximum load pressure. 1 Load sensing control of the hydraulic pump P1 is performed.

  On the other hand, the oil discharged from the second hydraulic pump P2 is sent to the second control valve group 50 to the third control valve group 60 and further sent to the second control valve group 50 via the oil passages 83 and 84. . Therefore, at this time, the maximum load pressure of the second hydraulic actuator group AG2 is sent to the pressure compensation valve disposed on the inlet side of the second control valve group 50, and these pressure compensation controls are performed. In this way, the switching that causes the maximum load pressure of the second hydraulic actuator group AG2 to act is performed by the third switching valve.

  Next, a case where the third hydraulic actuator group AG3 is operated will be described. The third control valve group 60 includes a swing control valve 61, a blade control valve 65, and an AUX control valve 66, and is operated by a left / right tilt operation of the left work operation lever 22 and an operation lever (not shown). The hydraulic oil supply to the cylinder 26 and the service port 27 is controlled. These control valves are supplied with hydraulic oil from the second hydraulic pump P2, and the swing control valve 61, the blade control valve 65 and the AUX control valve 66 supply this hydraulic oil to the swing motor 25, the blade cylinder 26 and the service port 27. Take control.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not restricted to the thing which concerns on the said embodiment. For example, an example in which a power shovel uses a crawler type traveling device is shown, but a wheeled traveling device may be used. Another combination may be used for the first to third hydraulic actuator groups. For example, the first hydraulic actuator group AG1 may be configured by the boom cylinder 15, the arm cylinder 16, and the bucket cylinder 17, and the second hydraulic actuator group AG2 may be configured by the right and left traveling motors 9R and 9L. It is also possible to use another hydraulic actuator.

  The power excavator has been described above as an example. However, the present invention is not limited to this, and the present invention can be applied to any device as long as it is a hydraulic operation device including a plurality of hydraulic actuators.

DESCRIPTION OF SYMBOLS 1 Excavator 3 Traveling mechanism 9R, 9L Right and left traveling motor (1st hydraulic actuator group AG1)
12 Boom 13 Arm 14 Bucket 15 Boom cylinder 16 Arm cylinder 17 Bucket cylinder 20 Operation lever 30 Controller 31 First switching valve 35 Second switching valve 40 First control valve group 50 Second control valve group 60 Third control valve group P1 1st hydraulic pump P2 2nd hydraulic pump P3 3rd hydraulic pump E Engine AG1 1st hydraulic actuator group AG2 2nd hydraulic actuator group AG3 3rd hydraulic actuator group HCU Hydraulic control unit

Claims (3)

First, second and third hydraulic actuator groups each having at least one hydraulic actuator;
A first control valve group composed of at least one control valve for performing hydraulic oil supply control to the hydraulic actuators constituting the first hydraulic actuator group;
A second control valve group comprising at least one control valve for performing hydraulic oil supply control to the hydraulic actuators constituting the second hydraulic actuator group;
A third control valve group comprising at least one control valve for performing hydraulic oil supply control to the hydraulic actuators constituting the third hydraulic actuator group;
First and second hydraulic oil supply sources for supplying hydraulic oil, respectively;
An operation device operated to operate the first to third hydraulic actuator groups, and a hydraulic operation device configured to include:
A first oil passage for supplying hydraulic oil from the first hydraulic oil supply source to the first control valve group;
A second oil passage connecting the first control valve group and the second control valve group;
A third oil passage for supplying hydraulic oil from the second hydraulic oil supply source to the third control valve group;
A fourth oil passage connecting the third control valve group and the second control valve group;
A first switching valve disposed in the second oil passage;
A second switching valve disposed in the fourth oil passage,
When operating any one of the first and second hydraulic actuator groups, the first switching valve is opened to allow hydraulic oil supply from the first control valve group to the second control valve group, And closing the second switching valve to restrict hydraulic oil supply from the third control valve group to the second control valve group,
When operating at least one hydraulic actuator of the first hydraulic actuator group and at least one hydraulic actuator of the second hydraulic actuator group together, the first switching valve is closed to release the first control valve group from the first control valve group. (2) The hydraulic oil supply to the control valve group is restricted, the second switching valve is opened, and the hydraulic oil supply from the third control valve group to the second control valve group is permitted. Features hydraulic actuator. It has a pilot oil passage to which pilot hydraulic pressure is supplied,
Each of the control valves constituting the first and second control valve groups includes a pilot control unit that performs control for communicating and blocking the pilot oil passage to the drain side,
Each of the pilot control units is configured to communicate the pilot oil passage to the drain side when the corresponding control valve is in the neutral position, and to shut off the pilot oil passage from the drain side when in the operating position,
When the pilot control unit in at least one control valve of the first control valve group and the pilot control unit in at least one control valve of the second control valve group are both shut off from the drain side, the pilot oil passage is piloted. Hydraulic pressure is generated, and the pilot hydraulic pressure acts on the first and second switching valves via the pilot oil passage to close the first switching valve and open the second switching valve. The hydraulic actuator according to claim 1. Each of the control valves constituting the first and second control valve groups includes a load pressure of a corresponding hydraulic actuator controlled by its own control valve, and a hydraulic actuator constituting the first and second hydraulic actuator groups. There is a pressure compensation valve that operates in response to the maximum load pressure of the load pressure,
When the first switching valve is closed to restrict the supply of hydraulic oil from the first control valve group to the second control valve group, the pressure compensation valve provided in the first control valve group includes 3. The hydraulic actuator according to claim 1, wherein a maximum load pressure of the hydraulic actuators constituting the two hydraulic actuator groups is not applied. 4.

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