JP4700447B2 - Hydraulic excavator with crane specification - Google Patents

Description

The present invention relates to a hydraulic excavator with a crane specification provided with a “crane mode” in which a crane work is performed using a hook attached to a work arm device in addition to a “normal mode” such as excavation and loading work.

This will be described with reference to FIG. The hydraulic excavator with crane specifications includes a hook 4 for crane work at the tip of a work arm device 6 attached to an upper swing body 5. The position of the hook 4 is moved by moving the work arm device 6. Since the allowable lifting load by the hook 4 varies depending on the position of the hook 4, a lifting load detection device is provided, and when the load lifted by the hook 4 becomes the rated load in the “crane mode”, the operator is notified by, for example, an overload alarm ( For example, see Patent Document 1).

The hydraulic excavator with crane specifications includes means for restricting the operation of the hydraulic actuator that moves the work arm device 4 so that the hook 4 does not move in the overload direction in the “crane mode”. The outline of the regulating means will be described with reference to FIG. 3 together with FIG.

Each of the operation valves of the operation valve unit 8 including a plurality of pilot operation valves operated by the operator controls a plurality of directions of the direction control valve unit 12 that controls the operation of the hydraulic actuator of the work arm device 6 by the pilot oil passage 10. Connected to each control valve.

The pilot oil passage 10 is provided with an electromagnetic valve unit 14 having a plurality of operation restricting solenoid valves for controlling the operation of a hydraulic actuator by controlling the operation of a predetermined direction control valve in the “crane mode”. Yes. The operation regulating solenoid valve controls pilot pressure oil in a predetermined pilot oil passage by a pre-programmed electric signal from the controller 16.

The solenoid valve unit 14 also outputs an oil amount regulating solenoid valve that outputs a control pressure for reducing the maximum discharge oil amount of the variable displacement pump 18 that discharges hydraulic oil to the flow rate control mechanism 20 of the pump in the “crane mode”. Is included.

The flow rate control mechanism 20 selects and inputs the control pressure of the oil amount regulating electromagnetic valve and the circuit pressure that fluctuates according to the operation state of the direction control valve unit 12, and the variable displacement pump 18 receives the input signal pressure. Negative control is performed to discharge an inversely proportional oil amount. Therefore, the hydraulic actuator in the “crane mode” is decelerated more than in the “normal mode” by the oil amount corresponding to the operation of the direction control valve within the range of the reduced maximum discharge oil amount.

The variable displacement pump 18 is mounted on the engine 22 located at the rear end of the upper swing body 5. The operation valve unit 8 is installed in the cab 5a. The direction control valve unit 12 is installed in the engine compartment 5b, which is intermediate between the cab 5a and the engine 22. The solenoid valve unit 14 is installed in the lower part of the cab 5a near the operation valve unit 8 that connects a number of pilot oil passage pipes. A control pressure pipe 24 that sends the control pressure of the oil amount regulating solenoid valve to the pump flow control mechanism 20 extends from the cab 5a to the pump 18 at the rear end of the upper swing body 5b.
Japanese Patent Laid-Open No. 11-232081 (FIGS. 1 and 2)

The conventional hydraulic excavator with crane specifications in the form as described above has the following problems to be solved.

In the control pressure pipe 24 of the oil amount regulating solenoid valve, pressure fluctuation and intense pulsation are generated by the control pressure of the oil amount regulating solenoid valve and the circuit pressure of the direction control valve unit 12. The control pressure pipe 24 is formed by a long hydraulic hose connecting the cab 5a and the pump 18. Therefore, since the control pressure pipe 24 is likely to vibrate and fluctuate, it is sufficient to prevent breakage due to contact with surrounding structures, pipes and the like, particularly in a portion close to the operator of the cab 5a. Piping is difficult due to the need for protection and proper routing. Furthermore, since the oil amount regulating solenoid valve is installed in an inaccessible portion under the floor of the cab 5a, the control pressure pipe 24 using a long hydraulic hose tends to make the control pressure transmitted to the flow control mechanism 20 of the pump unstable. Therefore, there is a problem that it is difficult to set the pressure of the oil amount regulating solenoid valve.

The present invention has been made in view of the above-mentioned fact, and the technical problem is that the control pressure piping that sends the control pressure of the oil amount regulating solenoid valve to the flow control mechanism of the variable displacement pump of the hydraulic excavator with crane specifications is provided. It is to solve difficult problems and problems such as the difficulty of setting the pressure of the oil amount regulating solenoid valve due to the arrangement of the oil amount regulating solenoid valve and the long control pressure piping.

According to the present invention, as a hydraulic excavator with a crane specification that solves the above technical problem, a plurality of directional control valves that respectively control a plurality of hydraulic actuators that operate a work arm device are connected via pilot oil passages. A pilot operation valve, an operation regulating solenoid valve provided near the pilot operation valve of a predetermined pilot oil passage, and which controls the pilot pressure oil to decelerate or stop the operation of the predetermined hydraulic actuator when in the “crane mode”; A pilot hydraulic pressure is applied to a predetermined control pressure (P3) that is provided in the vicinity of the flow rate control mechanism of the variable displacement pump that discharges the hydraulic fluid of the actuator and reduces the maximum discharged oil amount to a predetermined value (Q3) in the “crane mode”. oil amount regulating solenoid valve the pressure oil source and vacuum output to the flow control mechanism, control of the oil amount controlling solenoid valve The high pressure selection valve pressure and the directional control valve is incorporated in the valve body of the oil amount regulating solenoid valve to select the high-pressure side leading to the flow rate control mechanism of the circuit pressure in the oil passage leading to the tank when the neutral position A hydraulic excavator with a crane specification is provided.

The hydraulic excavator with crane specifications configured according to the present invention is provided with an oil amount regulating solenoid valve that outputs a control pressure to the flow control mechanism of the variable displacement pump in the vicinity of the flow control mechanism. Therefore, it is possible to substantially eliminate the control pressure piping that sends the control pressure, and it is difficult to connect the piping. Also, it is difficult to set the oil amount regulating solenoid valve due to the arrangement of the oil amount regulating solenoid valve and the long piping. Can be excluded.

Hereinafter, a hydraulic excavator with a crane specification configured according to the present invention will be described in more detail with reference to the accompanying drawings illustrating a preferred embodiment.

This will be described with reference to FIG. The hydraulic excavator with a crane specification includes an upper swing body 5 which is mounted on a lower traveling body 3 so as to be rotatable about a vertical axis, and a working arm device 6 in which a hook 4 for crane work is attached to the upper swing body 5. The cab 5a and the engine compartment 5b are provided.

The work arm device 6 includes a boom 6a attached to the upper swing body 5 so as to be swingable up and down, an arm 6b attached to the tip of the boom 6a so as to be swingable up and down, and swings up and down at the tip of the arm 6b. A freely mounted bucket 6c is provided, a boom cylinder 6d is provided between the upper swing body 5 and the boom 6a, an arm cylinder 6e is provided between the boom 6a and the arm 6b, and a bucket cylinder is provided between the arm 6b and the bucket 6c. 6f is provided. The hook 4 is attached to the connecting portion of the bucket 6 c at the tip of the working arm device 6.

The position of the hook 4 is moved by appropriately expanding and contracting the boom 6a, the arm 6b, and the bucket 6c of the boom cylinder 6d, the arm cylinder 6e, and the bucket cylinder 6f as hydraulic actuators.

Since the allowable lifting load of the hook 4 varies depending on the position of the hook 4, a lifting load detection device (not shown) is provided. The suspended load detection device calculates a suspended load by an arithmetic unit based on the posture of the work arm device 6 in a state where the load is suspended on the hook 4 and the hydraulic pressure generated in the hydraulic cylinder at that time, and lifts in that posture. Compare with allowable load. Since this suspension load detection device does not form a novel feature of the present invention, a detailed description thereof is omitted.

The hydraulic excavator with crane specifications includes means for restricting the operation of the hydraulic actuator of the work arm device 6 so that the hook 4 does not move in the overload direction exceeding the allowable lifting load in the “crane mode”; Means are provided for regulating the amount of oil discharged from a hydraulic pump that discharges hydraulic oil to slow down the operation.

With reference to FIG. 1 together with FIG. 2, a control hydraulic circuit of a crane-equipped hydraulic excavator provided with these regulating means will be described.

The control hydraulic circuit denoted by reference numeral 50 is each of the direction control valves 12a, 12b, 12c of the direction control valve unit 12 that controls the arm cylinder 6e, the bucket cylinder 6f, and the boom cylinder 6d that are hydraulic actuators for operating the work arm device 6. The pilot operating valves 8a, 8b, 8c of the operating valve unit 8 connected to the pilot oil passage 10 are provided in the vicinity of the pilot operating valves of the predetermined pilot oil passage. An electromagnetic valve unit 14 including operation regulating electromagnetic valves 14a, 14b, 14c that regulate and decelerate or stop the operation of a predetermined hydraulic actuator, and a flow rate control mechanism 20 of a variable displacement pump 18 that discharges hydraulic oil of the hydraulic actuator. Maximum discharge oil amount in the `` crane mode '' provided in the vicinity And a oil amount regulating solenoid valve 26 for outputting a control pressure to reduce the flow rate control mechanism 20.

The variable displacement pump 18 includes a pair of pumps directly connected to the engine 22.

The direction control valves 12a, 12b, 12c are operated by the pilot pressure oil of the pilot operation valves 8a, 8b, 8c. The direction control valve unit 12 further includes a direction control valve 12d for controlling the turning motor 5c for turning the upper turning body 5 and direction control valves 12e, 12f for controlling the pair of travel motors 3a, 3b, respectively. The directional control valve unit 12 is also a well-known mechanism, a pair of signal oil passages 30 and 30 for guiding the circuit pressure of the neutral oil passage leading to the tank 28 to the variable displacement pump 18 as a negative control pressure for controlling the amount of discharged oil. It has.

The pilot operation valves 8a, 8b, and 8c are well-known proportional pressure reducing valves that output the pilot pressure oil from the pilot hydraulic source 32 to the direction control valves 12a, 12b, and 12c via the pilot oil passage 10 at a pressure corresponding to the operation amount of the operator. It is.

In the pilot oil passage 10, the operation restricting electromagnetic valve 14a is provided in an oil passage (indicated by symbol B) that operates the arm cylinder 6e in the contraction direction, and the operation restriction electromagnetic valve 14b is an oil passage that operates the bucket cylinder 6f in the contraction direction. The operation regulating solenoid valve 14c is provided in an oil passage (indicated by reference symbol E) that operates the boom cylinder 6d in the extending direction.

The operation regulating solenoid valves 14a, 14b, 14c are operated by pre-programmed electrical signals from the controller 16 to regulate the pressure oil in the respective pilot oil passages to control the operation of predetermined hydraulic actuators. The predetermined hydraulic actuator is decelerated or stopped so that the hook 4 that suspends the load does not move in the overload direction.

The oil amount regulating solenoid valve 26 reduces the pressure oil of the pilot hydraulic source 32 to a predetermined pressure P3 (the pressure P3 will be described later) and outputs it in the “crane mode” by an electric signal from the controller 16. .

A high pressure side of the control pressure P3 of the oil amount regulating electromagnetic valve 26 and the circuit pressure P of the signal oil passage 30 of the direction control valve unit 12 is selected and guided to the pump flow control mechanism 20 via the high pressure selection valve 34. The high-pressure selection valve 34 is formed by a shuttle valve and is integrated in the valve body of the oil amount regulating electromagnetic valve 26.

The operation of the oil amount regulating electromagnetic valve 26 will be described with reference to FIG. The discharge oil amount Q of the variable displacement pump 18 is so-called negatively controlled by the signal pressure P input to the flow control mechanism 20. That is, the discharge oil amount Q depends on the magnitude of the signal pressure P between the minimum discharge oil amount Q1 defined on the high pressure side P1 of the signal pressure P and the maximum discharge oil amount Q2 defined on the low pressure side P2. Increased or decreased.

The high pressure P1 and the low pressure P2 are defined by the circuit pressure that varies depending on the switching of the direction control valve from the signal oil passage 30 of the direction control valve unit 12, and the discharge oil amount Q in the “normal mode” is as shown in FIG. As shown by the solid line, the circuit pressure, which is the signal pressure, is between the minimum discharge oil amount Q1 defined by the high pressure side pressure P1 and the maximum discharge oil amount Q2 defined by the low pressure side pressure P2. Increase / decrease is controlled accordingly.

The oil amount regulating solenoid valve 26 outputs a control pressure P3 between the high pressure P1 and the low pressure P2 so as to decrease the maximum discharged oil amount Q2 in the “crane mode”. Accordingly, as shown by the dotted line in FIG. 4, the discharge oil amount in the “crane mode” is defined by the pressure P3 on the low pressure side of the signal pressure, and by the maximum discharge oil amount Q3 and the pressure P1 defined by the pressure P3. Increase / decrease control is performed with respect to the minimum discharge oil amount Q1.

The effect of the crane-spec hydraulic excavator provided with the control hydraulic circuit 50 as described above will be described.

The hydraulic excavator with crane specifications provided with the control hydraulic circuit 50 is provided with an oil amount regulating electromagnetic valve 26 that outputs a control pressure to the flow control mechanism 20 of the variable displacement pump 18 in the vicinity of the flow control mechanism 20. Therefore, the control pressure pipe for sending the control pressure can be substantially removed, particularly from the vicinity of the operator of the cab 5a, and a pipe for avoiding vibration, fluctuation, damage, etc. in the conventional control pressure pipe is provided. Difficult problems can be eliminated.

Further, an oil amount regulating electromagnetic valve 26 is provided in the vicinity of the flow rate control mechanism 20 so that the poorly accessible part under the floor of the cab 5a is changed to the accessible engine room 5b, and further a long control pressure pipe for sending control pressure. Therefore, it is possible to eliminate the problem that it is difficult to set the pressure of the oil amount regulating solenoid valve due to the unstable control pressure caused by the arrangement of the conventional oil amount regulating solenoid valve and the control pressure piping.

Further, since the high pressure selection valve 34 for selecting and guiding the high pressure side of the control pressure and the circuit pressure is integrated into the valve body of the oil amount regulating electromagnetic valve 26 in the flow rate control mechanism 20 of the pump, the piping is further simplified. It is possible to eliminate the oil leakage problem due to poor assembly when a high pressure selection valve is installed in the middle of the piping, and the oil leakage failure can be improved by simplifying the piping.

1 is a control hydraulic circuit diagram of a hydraulic excavator with a crane specification configured according to the present invention. The side view of a hydraulic excavator with a crane specification. The outline explanatory view of the conventional regulation means. The characteristic diagram which shows the relationship between the signal pressure and the amount of discharged oil in a variable displacement hydraulic pump.

Explanation of symbols

6: Working arm device 6d: Boom cylinder (hydraulic actuator)
6e: Arm cylinder (hydraulic actuator)
6f: Bucket cylinder (hydraulic actuator)
8: Operating valve unit 8a: Pilot operating valve 8b: Pilot operating valve 8c: Pilot operating valve 10: Pilot oil passage 12: Direction control valve unit 14: Electromagnetic valve unit 14a: Operation restricting solenoid valve 14b: Operation restricting solenoid valve 14c: Operation restriction solenoid valve 18: Variable displacement pump 20: Flow rate control mechanism 26: Oil amount restriction solenoid valve 34: High pressure selection valve 50: Control hydraulic circuit

Claims (1)

A hydraulic excavator with crane specifications,
A plurality of pilot operating valves connected via pilot oil passages to respective directional control valves for controlling a plurality of hydraulic actuators for operating the work arm device;
An operation restricting solenoid valve that is provided in the vicinity of a pilot operation valve of a predetermined pilot oil passage and restricts the pilot pressure oil to decelerate or stop the operation of the predetermined hydraulic actuator when in the `` crane mode '';
Provided in the vicinity of the flow control mechanism of the variable displacement pump that discharges the hydraulic oil of the hydraulic actuator, when in the “crane mode”, the pilot controls a predetermined control pressure (P3) that reduces the maximum discharged oil amount to a predetermined value (Q3). An oil amount regulating solenoid valve for reducing the pressure oil of the hydraulic source and outputting it to the flow rate control mechanism ;
Built in the valve body of the oil amount restriction solenoid valve that selects the high pressure side of the control pressure of the oil amount restriction solenoid valve and the circuit pressure of the oil passage leading to the tank when the directional control valve is in the neutral position and leads to the flow control mechanism A high-pressure selection valve that is
A hydraulic excavator with crane specifications.

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