Work machine

Abstract

To provide a work machine capable of further reliably operating a vibration suppression device.SOLUTION: A work machine 1 includes a vehicle body, a work implement operably attached to the vehicle body, a second boom cylinder 512 that is a hydraulic cylinder for operating the work implement, and a vibration suppression device 10. The vibration suppression device 10 includes a discharge valve 24 connected between the hydraulic cylinder and a hydraulic oil tank 11, an accumulator control valve 25 connected between the hydraulic cylinder and an accumulator 13, a relay 22 having a first contact 221 that switches between a conductive state and a non-conductive state between a power source and an upstream terminal of the discharge valve 24, and a second contact 222 that switches between a conductive state and a non-conductive state between a downstream terminal of the accumulator control valve 25 and a ground 20G, and a controller 30. When an abnormality is detected in the electrical circuit of the vibration suppression device 10, the controller 30 does not place the first contact 221 and the second contact 222 of the relay in a conductive state and does not apply voltage to the upstream terminal of the accumulator control valve 25.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to work machines. [Background technology]

[0002] Construction machines equipped with working implements have a function to suppress vibrations that occur during travel. Patent Document 1 discloses a technology for preventing a boom from falling when the vibration suppression device (travel damper) operation is switched on in a hydraulic circuit for suppressing travel vibrations in a wheeled construction machine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-078633 Summary of the Invention [Problem to be solved by the invention]

[0004] In a work machine, it is desirable to operate the vibration suppression device more reliably. [Means for solving the problem]

[0005] According to the present disclosure, there is provided a work machine including a vehicle body, a work implement operably attached to the vehicle body, a hydraulic cylinder for operating the work implement, and a vibration suppression device. The vibration suppression device includes a discharge valve connected between the hydraulic cylinder and a hydraulic oil tank, an accumulator control valve connected between the hydraulic cylinder and an accumulator, a relay having a first contact unit that switches between a conductive state and a non-conductive state between a power source and an upstream terminal of the discharge valve, and a second contact unit that switches between a conductive state and a non-conductive state between a downstream terminal of the accumulator control valve and ground, and a controller. When an abnormality is detected in the electrical circuit of the vibration suppression device, the controller does not switch the first contact unit and the second contact unit of the relay into a conductive state and does not apply voltage to the upstream terminal of the accumulator control valve. [Effects of the Invention]

[0006] According to the present disclosure, a work machine can be provided that is capable of operating a vibration suppression device more reliably. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing a work machine according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram of a hydraulic circuit in the vibration suppression device according to the embodiment. [Figure 3] FIG. 3 is a schematic block diagram of a vibration suppression device according to an embodiment. [Figure 4] FIG. 4 is a block diagram illustrating an example of a computer system according to an embodiment. [Figure 5] FIG. 5 is a flowchart showing the processing carried out by the controller of the work machine according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the embodiments. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

[0009] [Work machinery] FIG. 1 is a perspective view showing a work machine 1 according to an embodiment. The work machine 1 comprises a vehicle body 2 and a work implement 4 operably attached to the vehicle body 2. The work machine 1 is, for example, a hydraulic excavator, a wheel loader, a forklift, a motor grader, or the like. In the embodiment, the work machine 1 is a hydraulic excavator. In the following description, the work machine 1 will be referred to as a hydraulic excavator 1 where appropriate. The hydraulic excavator 1 comprises the vehicle body 2, the work implement 4, and a work implement cylinder 5.

[0010] The vehicle body 2 includes a running body 2A and a revolving body 2B. The running body 2A has a pair of left and right front wheels 2F and a pair of left and right rear wheels 2R. The front wheels 2F and rear wheels 2R are rotated by a travel motor. The running body 2A travels due to the rotation of the front wheels 2F and rear wheels 2R. The revolving body 2B is rotatably supported on the running body 2A. A driver's cab 2C is provided on the revolving body 2B. The work implement 4 is operably attached to the vehicle body 2. In this embodiment, the work implement 4 is operably attached to the revolving body 2B. The work implement 4 includes a boom 41, an arm 42, and a bucket 43. In this embodiment, the boom 41 includes a first boom 411 and a second boom 412. The first boom 411 is rotatably connected to the revolving body 2B via a first boom pin. The second boom 412 is rotatably connected to the first boom 411 via a second boom pin. The arm 42 is rotatably connected to the second boom 412 via an arm pin. The bucket 43 is rotatably connected to the arm 42 via a bucket pin.

[0011] The work implement cylinders 5 operate the work implement 4. The work implement cylinders 5 are hydraulic cylinders. The work implement cylinders 5 include a first boom cylinder 511, a second boom cylinder 512, an arm cylinder 513, and a bucket cylinder 514.

[0012] [Vibration suppression device] Fig. 2 is a schematic diagram of a hydraulic circuit in a vibration suppression device 10 according to an embodiment. Fig. 3 is a schematic block diagram of the vibration suppression device 10 according to an embodiment. The vibration suppression device 10 is configured to be able to suppress shaking of the vehicle body 2 caused by vibrations while the hydraulic excavator 1 is traveling. As shown in Fig. 2, the hydraulic circuit of the vibration suppression device 10 includes a second boom cylinder 512, a hydraulic oil tank 11, an accumulator 13, a second boom control valve 18, a pilot control valve 15, a fall prevention valve (opening / closing control valve) 23, a discharge valve 24, and an accumulator control valve 25.

[0013] The second boom cylinder 512 is a hydraulic cylinder for operating the second boom 412 of the hydraulic excavator 1. The second boom cylinder 512 has a bottom chamber 512A and a head chamber 512B. The bottom chamber 512A is connected to the second boom control valve 18 and the accumulator control valve 25 via the fall prevention valve 23 in the hydraulic circuit. The head chamber 512B is connected to the second boom control valve 18 and the discharge valve 24 in the hydraulic circuit.

[0014] The second boom cylinder 512 extends and retracts to operate the second boom 412. Hydraulic oil is supplied from the second boom control valve 18 to the bottom chamber 512A and hydraulic oil is discharged from the head chamber 512B, thereby extending the second boom cylinder 512. When the second boom cylinder 512 extends, the second boom 412 operates to move the arm 42 and the bucket 43 away from the operator's cab 2C. When the second boom control valve 18 supplies hydraulic oil to the head chamber 512B and hydraulic oil is discharged from the bottom chamber 512A, the second boom cylinder 512 retracts. When the second boom cylinder 512 retracts, the second boom 412 operates to move the arm 42 and the bucket 43 closer to the operator's cab 2C.

[0015] Accumulator 13 is connected to the hydraulic circuit of second boom cylinder 512. Accumulator 13 functions as a damping device for suppressing vibrations during travel of the hydraulic excavator 1 by storing and discharging hydraulic oil in second boom cylinder 512. In the hydraulic circuit, accumulator 13 is connected to bottom chamber 512A of second boom cylinder 512 via accumulator control valve 25 and fall prevention valve 23. When second boom cylinder 512 retracts, at least a portion of the hydraulic oil discharged from bottom chamber 512A is supplied to accumulator 13. Accumulator 13 is configured to be able to store pressure using hydraulic oil supplied from bottom chamber 512A.

[0016] When the vibration suppression device 10 is active, the accumulator 13 configured in this manner functions as a damping device for suppressing vibrations during travel of the hydraulic excavator 1. More specifically, when the fall prevention valve 23, the discharge valve 24, and the accumulator control valve 25 are open, the accumulator 13 functions as a damping device for suppressing vibrations during travel of the hydraulic excavator 1.

[0017] Hydraulic oil tank 11 is a tank for storing hydraulic oil for hydraulic excavator 1. Hydraulic oil tank 11 is configured to be able to store hydraulic oil discharged from bottom chamber 512A or head chamber 512B of second boom cylinder 512. Hydraulic oil tank 11 is connected to second boom control valve 18 and head chamber 512B of second boom cylinder 512 via discharge valve 24 in the hydraulic circuit.

[0018] Second boom control valve 18 supplies hydraulic oil for driving second boom cylinder 512 from hydraulic pump 19 based on operation of a second boom operating device (not shown) by an operator. Second boom control valve 18 is configured to be able to supply hydraulic oil to a bottom chamber 512A of second boom cylinder 512 and a head chamber 512B of second boom cylinder 512. Second boom control valve 18 is connected to bottom chamber 512A of second boom cylinder 512 via fall prevention valve 23 in the hydraulic circuit. Second boom control valve 18 is connected to head chamber 512B of second boom cylinder 512 in the hydraulic circuit.

[0019] The second boom control valve 18 adjusts the flow rate of hydraulic oil supplied to the second boom cylinder 512 based on the amount of operation of the second boom operation device. As the amount of operation of the second boom operation device increases, the second boom control valve 18 increases the flow rate of hydraulic oil supplied to the second boom cylinder 512. This increases the extension and retraction speed of the second boom cylinder 512. As the amount of operation of the second boom operation device decreases, the second boom control valve 18 reduces the flow rate of hydraulic oil supplied to the second boom cylinder 512. This decreases the extension and retraction speed of the second boom cylinder 512.

[0020] The pilot control valve 15 controls the pilot hydraulic pressure for operating the fall prevention valve 23. The pilot control valve 15 is connected to a pilot port 23c of the fall prevention valve 23 in the hydraulic circuit. The pilot control valve 15 is configured as a switching valve whose valve position can be switched between a first position 15a and a second position 15b. The valve position of the pilot control valve 15 is switched to either the first position 15a or the second position 15b based on a control signal from a controller 30, which will be described later. The pilot control valve 15 has a pilot control valve solenoid 15c.

[0021] When the valve position is located at first position 15a, pilot control valve 15 applies first pilot hydraulic pressure, which is supplied based on the operation of the second boom operation device, to pilot port 23c of fall prevention valve 23. When the valve position is located at second position 15b, pilot control valve 15 applies second pilot hydraulic pressure, which is constantly supplied at a predetermined pressure, to pilot port 23c of fall prevention valve 23.

[0022] When the vibration suppression device 10 is enabled, the valve position of the pilot control valve 15 is controlled to be in the second position 15b. When the vibration suppression device 10 is disabled, the valve position of the pilot control valve 15 is controlled to be in the first position 15a.

[0023] Fall prevention valve 23 is configured to be able to maintain the internal pressure of bottom chamber 512A of second boom cylinder 512. Fall prevention valve 23 is connected to bottom chamber 512A of second boom cylinder 512 in the hydraulic circuit. Fall prevention valve 23 is connected to second boom control valve 18 and accumulator control valve 25 in the hydraulic circuit.

[0024] The fall prevention valve 23 has its valve position controlled by pilot oil pressure supplied from the pilot control valve 15 between a closed position 23a, where hydraulic oil cannot move, and a communicating position 23b, where hydraulic oil can move mutually.

[0025] When the valve position of pilot control valve 15 is located at first position 15a, the valve position of fall prevention valve 23 is controlled between closed position 23a and communicating position 23b by first pilot hydraulic pressure supplied based on the operation of the second boom operation device by the operator. When the valve position of pilot control valve 15 is located at second position 15b, the valve position of fall prevention valve 23 is controlled so as to always be in communicating position 23b by second pilot hydraulic pressure constantly supplied at a predetermined pressure.

[0026] When the vibration suppression device 10 is effective, the valve position of the fall prevention valve 23 is controlled by the second pilot hydraulic pressure so that it is always in the communicating position 23b. When the vibration suppression device 10 is effective, the fall prevention valve 23 is controlled by the second pilot hydraulic pressure passing through the pilot control valve 15 so that it is always kept in the communicating state.

[0027] When vibration suppression device 10 is disabled, the valve position of fall prevention valve 23 is controlled between closed position 23a and connected position 23b by the first pilot hydraulic pressure. When vibration suppression device 10 is disabled, fall prevention valve 23 is controlled between a closed state and a connected state in accordance with the first pilot hydraulic pressure passing through pilot control valve 15. More specifically, when vibration suppression device 10 is disabled, the valve position of fall prevention valve 23 is controlled to connected position 23b in accordance with the operation of the operator to retract second boom cylinder 512. As a result, fall prevention valve 23 is controlled so as to be able to discharge hydraulic oil from bottom chamber 512A of second boom cylinder 512.

[0028] Discharge valve 24 is configured to be able to discharge hydraulic oil from head chamber 512B of second boom cylinder 512 to hydraulic oil tank 11. Discharge valve 24 is connected in the hydraulic circuit between head chamber 512B of second boom cylinder 512 and hydraulic oil tank 11. Discharge valve 24 has a discharge valve solenoid 24c.

[0029] The discharge valve 24 is configured as a switching valve whose valve position can be switched between a closed position 24a, at which the hydraulic oil cannot be discharged to the hydraulic oil tank 11, and a communicating position 24b, at which the hydraulic oil can be discharged to the hydraulic oil tank 11. The valve position of the discharge valve 24 is switched to either the closed position 24a or the communicating position 24b based on a control signal from the controller 30.

[0030] When the valve position is in the closed position 24a, the hydraulic oil in the head chamber 512B of the second boom cylinder 512 does not pass through the discharge valve 24 and is not discharged into the hydraulic oil tank 11. When the valve position is in the communicating position 24b, the hydraulic oil in the head chamber 512B of the second boom cylinder 512 passes through the discharge valve 24 and is discharged into the hydraulic oil tank 11.

[0031] Accumulator control valve 25 is configured to be able to supply hydraulic oil from bottom chamber 512A of second boom cylinder 512 to accumulator 13. Accumulator control valve 25 is connected in the hydraulic circuit between fall prevention valve 23 and accumulator 13. Accumulator control valve 25 has an accumulator control valve solenoid 25c.

[0032] The accumulator control valve 25 is configured as a switching valve whose valve position can be switched between a closed position 25a, at which hydraulic oil cannot be supplied to the accumulator 13, and a communication position 25b, at which hydraulic oil can be supplied to the accumulator 13. The valve position of the accumulator control valve 25 is switched to either the closed position 25a or the communication position 25b based on a control signal from the controller 30.

[0033] When the valve is in the closed position 25a, the hydraulic oil in the bottom chamber 512A of the second boom cylinder 512 does not pass through the accumulator control valve 25 and is not supplied to the accumulator 13. When the valve is in the communicating position 25b, the hydraulic oil in the bottom chamber 512A of the second boom cylinder 512 passes through the accumulator control valve 25 and is supplied to the accumulator 13.

[0034] Vibration suppression device 10 controls the operation of accumulator 13 connected to the hydraulic circuit of second boom cylinder 512, as shown in Fig. 2. As shown in Fig. 3, vibration suppression device 10 includes an operation switch 21, a relay 22, a pilot control valve solenoid 15c, a discharge valve solenoid 24c, an accumulator control valve solenoid 25c, a vehicle speed sensor 29, and a controller 30.

[0035] The operation switch 21 is a switch that accepts an operation to switch the vibration suppression device 10 between enabled (ON) and disabled (OFF). The operation switch 21 is electrically connected to the controller 30 via an electric signal line 211 and an electric signal line 212. The operation switch 21 is operated by an operator. When operated by the operator, the operation switch 21 outputs an operation signal to the controller 30. When the operation switch 21 is operated "ON", the operation switch 21 outputs a signal indicating an "ON" operation. When the operation switch 21 is operated "OFF", the operation switch 21 outputs a signal indicating an "OFF" operation. The operation switch 21 is arranged in the operator's cab 2C of the hydraulic excavator 1.

[0036] The relay 22 is controlled to be opened or closed by a control signal from the controller 30. The relay 22 includes a first contact portion 221, a second contact portion 222, and a coil portion 223.

[0037] The first contact 221 is disposed between the upstream terminal of the pilot control valve solenoid 15c and the upstream terminal of the discharge valve solenoid 24c and the power supply. The first contact 221 switches between a conductive state and a non-conductive state of an electrical circuit connecting the power supply to the upstream terminal of the pilot control valve solenoid 15c and the upstream terminal of the discharge valve solenoid 24c. The first contact 221 is configured to electrically connect or disconnect the power supply to the upstream terminal of the pilot control valve solenoid 15c and the upstream terminal of the discharge valve solenoid 24c.

[0038] The second contact portion 222 is disposed between the downstream terminal of the accumulator control valve solenoid 25c and the ground 20G. The second contact portion 222 switches between a conductive state and a non-conductive state of an electric circuit connecting the downstream terminal of the accumulator control valve solenoid 25c and the ground 20G. The second contact portion 222 is configured to electrically connect or disconnect the downstream terminal of the accumulator control valve solenoid 25c and the ground 20G.

[0039] The coil portion 223 switches the first contact portion 221 and the second contact portion 222 between a conductive state and a non-conductive state. The coil portion 223 is electrically connected to a first output terminal 301 of the controller 30 via an electric signal line 2231. The coil portion 223 is controlled based on a control signal from the controller 30. When the coil portion 223 is in an excited state, the first contact portion 221 and the second contact portion 222 are in a conductive state. When the coil portion 223 is in a demagnetized state, the first contact portion 221 and the second contact portion 222 are in a non-conductive state.

[0040] When the first contact 221 is in a conductive state, the power supply is electrically connected to the upstream terminal of the pilot control valve solenoid 15c and the upstream terminal of the discharge valve solenoid 24c. When the second contact 222 is in a conductive state, the downstream terminal of the accumulator control valve solenoid 25c is electrically connected to the ground 20G. When the first contact 221 is in a non-conductive state, the power supply is electrically disconnected from the upstream terminal of the pilot control valve solenoid 15c and the upstream terminal of the discharge valve solenoid 24c. When the second contact 222 is in a non-conductive state, the downstream terminal of the accumulator control valve solenoid 25c is electrically disconnected from the ground 20G.

[0041] The pilot control valve solenoid 15c controls the valve position of the pilot control valve 15. The upstream terminal of the pilot control valve solenoid 15c is connected to the first contact 221 of the relay 22. The downstream terminal of the pilot control valve solenoid 15c is connected to the ground 20G. When the coil 223 is in an excited state, the upstream terminal of the pilot control valve solenoid 15c is electrically connected to the power supply. When the upstream terminal of the pilot control valve solenoid 15c is electrically connected to the power supply, the pilot control valve solenoid 15c is excited. When the pilot control valve solenoid 15c is excited, the pilot control valve solenoid 15c switches the valve position of the pilot control valve 15 to the second position 15b. When the coil 223 is in a de-energized state, the upstream terminal of the pilot control valve solenoid 15c is electrically disconnected from the power supply. When the electrical connection between the upstream terminal of the pilot control valve solenoid 15c and the power supply is interrupted, the pilot control valve solenoid 15c is de-energized, and switches the valve position of the pilot control valve 15 to the first position 15a.

[0042] The discharge valve solenoid 24c controls the valve position of the discharge valve 24. An upstream terminal of the discharge valve solenoid 24c is connected to a first contact portion 221 of the relay 22. A downstream terminal of the discharge valve solenoid 24c is connected to the ground 20G. When the coil portion 223 is in an excited state, the upstream terminal of the discharge valve solenoid 24c is electrically connected to the power supply. When the upstream terminal of the discharge valve solenoid 24c is electrically connected to the power supply, the discharge valve solenoid 24c is excited. When the discharge valve solenoid 24c is excited, the discharge valve solenoid 24c switches the valve position of the discharge valve 24 to the communicating position 24b. When the coil portion 223 is in a demagnetized state, the upstream terminal of the discharge valve solenoid 24c is electrically disconnected from the power supply. When the electrical connection between the upstream terminal of the discharge valve solenoid 24c and the power supply is interrupted, the discharge valve solenoid 24c is de-energized, and switches the valve position of the discharge valve 24 to the closed position 24a.

[0043] The accumulator control valve solenoid 25c controls the valve position of the accumulator control valve 25. An upstream terminal of the accumulator control valve solenoid 25c is electrically connected to a second output terminal 302 of the controller 30. The upstream terminal of the accumulator control valve solenoid 25c is electrically connected to the controller 30 via an electrical signal line 25c1. A downstream terminal of the accumulator control valve solenoid 25c is connected to a second contact portion 222 of the relay 22. When the coil portion 223 is in an excited state, the downstream terminal of the accumulator control valve solenoid 25c is electrically connected to ground 20G. When the downstream terminal of the accumulator control valve solenoid 25c is electrically connected to ground 20G, the accumulator control valve solenoid 25c is excited. When the accumulator control valve solenoid 25c is energized, the accumulator control valve solenoid 25c switches the valve position of the accumulator control valve 25 to the communicating position 25b. When the coil portion 223 is deenergized, the downstream terminal of the accumulator control valve solenoid 25c is electrically disconnected from the ground 20G. When the electrical connection between the downstream terminal of the accumulator control valve solenoid 25c and the ground 20G is disconnected, the accumulator control valve solenoid 25c is deenergized. When the accumulator control valve solenoid 25c is deenergized, the accumulator control valve solenoid 25c switches the valve position of the accumulator control valve 25 to the closed position 25a.

[0044] The vehicle speed sensor 29 detects the traveling speed of the hydraulic excavator 1. The vehicle speed sensor 29 outputs a speed signal indicating the detected traveling speed of the hydraulic excavator 1.

[0045] [controller] The controller 30 controls the hydraulic excavator 1 so as to suppress shaking of the vehicle body 2 caused by vibrations during travel. The controller 30 includes a numerical calculation device (processor) such as a CPU (Central Processing Unit).

[0046] 4 is a block diagram showing an example of a computer system according to an embodiment. The controller 30 includes a computer system 1000. The computer system 1000 includes a processor 1001 such as a CPU, a main memory 1002 including a nonvolatile memory such as a read-only memory (ROM) and a volatile memory such as a random access memory (RAM), a storage 1003, and an interface 1004 including an input / output circuit. The functions of the controller 30 described above are stored as a program in the storage 1003. The processor 1001 reads the program from the storage 1003, loads it into the main memory 1002, and executes the above-described processing in accordance with the program. The program may be distributed to the computer system 1000 via a network.

[0047] As shown in FIG. 3, the controller 30 includes a monitoring unit 31, a signal receiving unit 32, a command control unit 33, and an output unit .

[0048] The monitoring unit 31 detects abnormalities in the electrical circuit of the vibration suppression device 10. Examples of abnormalities include a short to the power supply in the electrical signal line and stuck contacts of the relay 22. The monitoring unit 31 detects abnormalities based on, for example, a change in the voltage or current applied to the electrical circuit of the vibration suppression device 10.

[0049] The monitoring unit 31 detects an abnormality such as a short to power in the electric signal line 2231 connecting the first output terminal 301 of the controller 30 and the coil unit 223. For example, when the monitoring unit 31 detects that a voltage equal to or greater than a threshold value is being applied to the electric signal line 2231 in a state in which the command control unit 33 described below is not outputting a command signal to excite the coil unit 223, the monitoring unit 31 determines that an abnormality such as a short to power has occurred in the electric signal line 2231.

[0050] The monitoring unit 31 detects an abnormality, such as a short to power, in the electric signal line 25c1 that connects the second output terminal 302 of the controller 30 and the upstream terminal of the accumulator control valve solenoid 25c. For example, when the monitoring unit 31 detects that a voltage equal to or greater than a threshold value is being applied to the electric signal line 25c1 in a state in which the command control unit 33 is not outputting a command signal to excite the accumulator control valve solenoid 25c, the monitoring unit 31 determines that an abnormality, such as a short to power, has occurred in the electric signal line 25c1.

[0051] The monitoring unit 31 detects an abnormality such as sticking of the second contact portion 222 of the relay 22. For example, when the monitoring unit 31 detects that a current equal to or greater than a threshold value is flowing through the electric signal line 25c1 connecting the second output terminal 302 of the controller 30 and the upstream terminal of the accumulator control valve solenoid 25c while the command control unit 33 is not outputting a command signal to excite the coil portion 223, the monitoring unit 31 determines that an abnormality such as sticking has occurred in the coil portion 223.

[0052] The monitoring unit 31 outputs an abnormality signal indicating the abnormality when it determines that an abnormality has occurred in the electric circuit of the vibration suppression device 10. Note that the monitoring unit 31 may output an abnormality signal indicating that an abnormality has occurred at each location where it has determined that an abnormality has occurred in the electric circuit of the vibration suppression device 10.

[0053] The signal receiving unit 32 receives an operation signal from the operation switch 21. The signal receiving unit 32 includes a first signal receiving unit 321 and a second signal receiving unit 322. The first signal receiving unit 321 receives a signal indicating an "ON" operation from the operation switch 21. The second signal receiving unit 322 receives a signal indicating an "OFF" operation from the operation switch 21. The signal receiving unit 32 outputs the operation signal received from the operation switch 21 to the command control unit 33.

[0054] The command control unit 33 outputs a command signal to the output unit 34 to operate the vibration suppression device 10 based on the operation signal from the signal receiving unit 32 and the speed signal from the vehicle speed sensor 29 .

[0055] The command control unit 33 determines that the enabling conditions for the vibration suppression device 10 are satisfied when the first signal receiving unit 321 receives a signal indicating an "ON" operation from the operation switch 21 and the traveling speed of the hydraulic excavator 1 is equal to or greater than a threshold value. If it is determined that the enabling conditions for the vibration suppression device 10 are satisfied, the command control unit 33 outputs a command signal to the output unit 34 to cause the accumulator 13 to function as a damping device for suppressing vibrations when the hydraulic excavator 1 is traveling.

[0056] If the second signal receiving unit 322 receives a signal indicating an "OFF" operation from the operation switch 21, or if the traveling speed of the hydraulic excavator 1 is less than a threshold value, the command control unit 33 determines that the enabling conditions for the vibration suppression device 10 are not satisfied. If it is determined that the enabling conditions for the vibration suppression device 10 are not satisfied, the command control unit 33 does not output a command signal to the output unit 34.

[0057] In the embodiment, the threshold driving speed is, for example, 5 km / h.

[0058] The command control unit 33 outputs a command signal for controlling the relay 22. If the command control unit 33 determines that the enabling conditions for the vibration suppression device 10 are satisfied, the command control unit 33 outputs a command signal for closing the first contact unit 221 and the second contact unit 222 of the relay 22. Specifically, if the command control unit 33 determines that the enabling conditions for the vibration suppression device 10 are satisfied, the command control unit 33 outputs a command signal for exciting the coil unit 223 of the relay 22. If the command control unit 33 determines that the enabling conditions for the vibration suppression device 10 are not satisfied, the command control unit 33 does not output a command signal for closing the first contact unit 221 and the second contact unit 222 of the relay 22. Specifically, if the command control unit 33 determines that the enabling conditions for the vibration suppression device 10 are not satisfied, the command control unit 33 does not output a command signal for exciting the coil unit 223 of the relay 22.

[0059] The command control unit 33 outputs a command signal for controlling the accumulator control valve 25. When the command control unit 33 determines that the enabling conditions for the vibration suppression device 10 are satisfied, it outputs a command signal for switching the valve position of the accumulator control valve 25 to the communicating position 25b. Specifically, when the command control unit 33 determines that the enabling conditions for the vibration suppression device 10 are satisfied, it outputs a command signal for exciting the accumulator control valve solenoid 25c. When the command control unit 33 determines that the enabling conditions for the vibration suppression device 10 are not satisfied, it does not output a command signal for switching the valve position of the accumulator control valve 25 to the communicating position 25b. Specifically, when the command control unit 33 determines that the enabling conditions for the vibration suppression device 10 are not satisfied, it does not output a command signal for exciting the accumulator control valve solenoid 25c.

[0060] Based on the abnormality signal from the monitoring unit 31 and the command signal from the command control unit 33, the output unit 34 applies a voltage to the coil unit 223 of the relay 22 and the accumulator control valve solenoid 25c.

[0061] When the output unit 34 does not receive an abnormality signal from the monitoring unit 31 and receives a command signal from the command control unit 33 to excite the coil unit 223, the output unit 34 applies a voltage to the coil unit 223. When the output unit 34 does not receive an abnormality signal from the monitoring unit 31 and receives a command signal from the command control unit 33 to excite the accumulator control valve solenoid 25c, the output unit 34 applies a voltage to the accumulator control valve solenoid 25c.

[0062] When the output unit 34 receives an abnormality signal from the monitoring unit 31, it does not apply a voltage to the coil 223 so that the first contact 221 and the second contact 222 of the relay 22 are not brought into a conductive state, regardless of the command signal from the command control unit 33. Furthermore, when the output unit 34 receives an abnormality signal from the monitoring unit 31, it does not apply a voltage to the accumulator control valve solenoid 25c so that the accumulator control valve solenoid 25c is not excited, regardless of the command signal from the command control unit 33.

[0063] [Control processing of vibration suppression device] Next, the processing procedure of the embodiment will be described with reference to the flowchart shown in Fig. 5. Fig. 5 is a flowchart showing the processing content performed by the controller 30 of the hydraulic excavator 1 according to the first embodiment.

[0064] The monitoring unit 31 detects an abnormality in the electric circuit of the vibration suppression device 10 (step ST11). If an abnormality in the electric circuit of the vibration suppression device 10 is not detected (No in step ST11), the process proceeds to step ST12. If an abnormality in the electric circuit of the vibration suppression device 10 is detected (Yes in step ST11), the process ends.

[0065] The command control unit 33 determines whether or not a signal indicating an "ON" operation has been received from the operation switch 21 (step ST12). If it is determined that a signal indicating an "ON" operation has been received (Yes in step ST12), the command control unit 33 proceeds to step ST13. If it is determined that a signal indicating an "ON" operation has not been received (No in step ST12), the command control unit 33 ends this processing.

[0066] If it is determined that a signal indicating an "ON" operation has been received (Yes in step ST12), the command control unit 33 determines whether the traveling speed of the hydraulic excavator 1 is equal to or greater than a threshold value (step ST13). If it is determined that the traveling speed is equal to or greater than the threshold value (Yes in step ST13), the command control unit 33 proceeds to step ST14. If it is determined that the traveling speed is less than the threshold value (No in step ST13), the command control unit 33 ends this processing.

[0067] If it is determined that the traveling speed is greater than or equal to the threshold value (Yes in step ST13), the command control unit 33 outputs a command signal to the output unit 34 to cause the accumulator 13 to function as a damping device to suppress vibrations when the hydraulic excavator 1 is traveling (step ST14).

[0068] The output unit 34 applies a voltage to the coil unit 223 of the relay 22 and the accumulator control valve solenoid 25c (step ST15).

[0069] [effect] As described above, in the embodiment, the vibration suppression device 10 includes the discharge valve 24 connected between the head chamber 512B of the second boom cylinder 512 and the hydraulic oil tank 11, the accumulator control valve 25 connected between the bottom chamber 512A of the second boom cylinder 512 and the accumulator 13, the relay 22, and the controller 30. The relay 22 has a first contact 221 that switches between a conductive state and a non-conductive state between the power supply and the upstream terminal of the discharge valve solenoid 24c, and a second contact 222 that switches between a conductive state and a non-conductive state between the downstream terminal of the accumulator control valve solenoid 25c and the ground 20G. In the embodiment, when an abnormality in the electrical circuit of the vibration suppression device 10 is detected, the controller 30 does not apply voltage to the coil 223 of the relay 22, thereby preventing the first contact 221 and the second contact 222 of the relay 22 from being conductive. This prevents the accumulator 13 from functioning as a damping device. According to the embodiment, it is possible to provide a work machine 1 that is capable of operating the vibration suppression device 10 more reliably.

[0070] In this embodiment, when the controller 30 detects an abnormality in the electrical circuit of the vibration suppression device 10, it does not apply voltage to the upstream terminal of the accumulator control valve solenoid 25c, preventing the accumulator control valve solenoid 25c from being excited. This prevents the accumulator 13 from functioning as a damping device. According to this embodiment, it is possible to provide a work machine 1 that can operate the vibration suppression device 10 more reliably.

[0071] In the embodiment, when the controller 30 detects no abnormality in the electric circuit of the vibration suppression device 10 and determines that the enabling condition of the vibration suppression device 10 is satisfied, the controller 30 brings the first contact portion 221 and the second contact portion 222 into a conductive state and applies a voltage to the upstream terminal of the accumulator control valve solenoid 25c. As a result, according to the embodiment, the accumulator 13 can fulfill the function of the vibration suppression device 10.

[0072] In this embodiment, when a signal indicating an "ON" operation is received from the operation switch 21 and the traveling speed of the hydraulic excavator 1 is equal to or greater than a threshold, it is determined that the enabling conditions for the vibration suppression device 10 are satisfied. According to this embodiment, the vibration suppression device 10 can exert its vibration suppression function under appropriate conditions.

[0073] [Variations] The output unit 34 in the above embodiment may perform the following processing. The output unit 34 may perform control to prevent a voltage from being applied to either the coil unit 223 or the accumulator control valve solenoid 25c, depending on the location where the monitoring unit 31 determines that an abnormality has occurred. For example, if a short-to-power circuit has occurred in the electrical signal line 2231, the output unit 34 may perform control to prevent a voltage from being applied to the accumulator control valve solenoid 25c. For example, if a short-to-power circuit has occurred in the electrical signal line 25c1, the output unit 34 may perform control to prevent a voltage from being applied to the coil unit 223. For example, if a sticking of the coil unit 223 has occurred, the output unit 34 may perform control to prevent a voltage from being applied to the accumulator control valve solenoid 25c.

[0074] [Other variations] In the above embodiment, the work machine 1 has been described as a hydraulic excavator equipped with a two-piece boom, but is not limited to this and can also be applied to, for example, a hydraulic excavator equipped with a single boom or an offset boom.

[0075] In the above embodiment, the command control unit 33 outputs a command signal to the output unit 34 to operate the vibration suppression device 10 based on an operation signal from the signal receiving unit 32 and a speed signal from the vehicle speed sensor 29. However, instead of the vehicle speed sensor 29, the command signal to operate the vibration suppression device 10 may also be output to the output unit 34 based on a signal from, for example, a work equipment lock switch that enables or disables the operation of the work equipment 4 in response to the operator's operation. [Explanation of symbols]

[0076] 1...hydraulic excavator (work machine), 2...body, 2A...traveling body, 2B...swivel body, 2C...operator's cab, 2F...front wheels, 2R...rear wheels, 4...working machine, 5...working machine cylinder, 512...second boom cylinder (hydraulic cylinder), 512A...bottom chamber, 512B...head chamber, 10...vibration suppression device, 11...hydraulic oil tank, 13...accumulator, 20G...gland, 21...operating switch, 22...relay, 221...first contact portion, 222...second contact portion, 223...coil portion, 23...fall prevention valve (opening / closing control valve), 24...discharge valve, 25...accumulator control valve, 29...vehicle speed sensor, 30...controller, 31...monitoring unit, 32...signal receiving unit, 33...command control unit, 34...output unit.

Claims

1. A work machine comprising a vehicle body, a work implement operably attached to the vehicle body, a hydraulic cylinder for operating the work implement, and a vibration suppression device. The vibration suppression device a drain valve connected between the hydraulic cylinder and a hydraulic oil tank; an accumulator control valve connected between the hydraulic cylinder and an accumulator; a relay including: a first contact portion that switches between a conductive state and a non-conductive state between a power source and an upstream terminal of the discharge valve; and a second contact portion that switches between a conductive state and a non-conductive state between the downstream terminal of the accumulator control valve and ground; A controller; Equipped with The controller When an abnormality is detected in the electrical circuit of the vibration suppression device, The first contact portion and the second contact portion of the relay are not in a conductive state, No voltage is applied to the upstream terminal of the accumulator control valve; Work machinery.

2. The controller If it is determined that no abnormality is detected in the electrical circuit of the vibration suppression device and that the valid conditions for the vibration suppression device are satisfied, The first contact portion and the second contact portion are brought into a conductive state, applying a voltage to an upstream terminal of the accumulator control valve; 2. The work machine according to claim 1.

3. The controller receiving a signal from a switch that accepts an operation to switch between enabling and disabling the vibration suppression device; determining that the enabling condition for the vibration suppression device is satisfied when a signal indicating that the vibration suppression device should be enabled is received from the switch and the traveling speed of the work machine is equal to or greater than a threshold value; 3. The work machine according to claim 2.

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