WO2019017318A1 - Hydraulic drive device and hydraulic drive system provided therewith - Google Patents

Hydraulic drive device and hydraulic drive system provided therewith Download PDF

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Publication number
WO2019017318A1
WO2019017318A1 PCT/JP2018/026663 JP2018026663W WO2019017318A1 WO 2019017318 A1 WO2019017318 A1 WO 2019017318A1 JP 2018026663 W JP2018026663 W JP 2018026663W WO 2019017318 A1 WO2019017318 A1 WO 2019017318A1
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WO
WIPO (PCT)
Prior art keywords
pressure
control valve
output
pilot
electromagnetic proportional
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PCT/JP2018/026663
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French (fr)
Japanese (ja)
Inventor
哲弘 近藤
知道 能勢
直希 畑
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川崎重工業株式会社
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Publication of WO2019017318A1 publication Critical patent/WO2019017318A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B20/00—Safety arrangements for fluid actuator systems; Applications of safety devices in fluid actuator systems; Emergency measures for fluid actuator systems

Definitions

  • the present invention relates to a hydraulic drive unit that drives hydraulic actuators by flowing hydraulic fluid from a main pump to a hydraulic actuator, and a hydraulic drive system including the same.
  • the hydraulic actuator is driven by hydraulic oil from the main pump, and the main pump constitutes a hydraulic drive circuit together with the multi-control valve.
  • the direction and flow rate of hydraulic fluid flowing from the main pump to the hydraulic actuator are controlled by the multi-control valve, whereby the movement of the hydraulic actuator is controlled.
  • a hydraulic drive circuit having such a function, a hydraulic drive circuit as described in, for example, Patent Document 1 is known.
  • the pilot pressure input to the multi-control valve is controlled by the electromagnetic proportional control valve. That is, the operation amount of the operation lever is input to the control device, and the control device controls the movement of the electromagnetic proportional control valve so as to apply the pilot pressure according to the input operation amount to the spool of the multi-control valve.
  • hydraulic fluid having a flow rate corresponding to the amount of operation is guided to the hydraulic actuator, and the hydraulic actuator can be moved at a speed according to the amount of operation.
  • the following problems may occur in the electromagnetic proportional control valve. That is, a failure may occur in the wiring path such as disconnection of a signal line connecting the electromagnetic proportional control valve and the control device. In this case, even if the control lever is operated, the primary pressure passage and the secondary pressure (output) passage of the electromagnetic proportional control valve continue to be blocked, and the output pressure from the electromagnetic proportional control valve remains zero. It becomes. In addition, a failure may occur such as sticking in a state in which the valve body of the electromagnetic proportional control valve shuts off the passage on the primary pressure side and the passage on the secondary pressure side of the electromagnetic proportional control valve. As is the case, the output pressure from the proportional solenoid valve remains zero.
  • the present invention provides a hydraulic drive device capable of operating a hydraulic actuator according to the operation of the operating device even if a failure occurs such that the output pressure from the electromagnetic proportional control valve is maintained at zero. It is an object of the present invention to provide a hydraulic drive system comprising:
  • two pilot pressures are input in the opposite direction to each other, and movement according to the pressure difference between the two pilot pressures is performed in one and the other in the predetermined directions and flows from the main pump to the hydraulic actuator
  • a flow control valve having a spool that switches the direction of oil and controls the opening between the main pump and the hydraulic actuator, and pressure oil supplied from a pressure source that supplies pressure oil maintained at a constant set pressure
  • a proportional proportional type electromagnetic proportional control valve wherein the first output pressure is controlled to be one of the two pilot pressures.
  • a direct proportional type first electromagnetic proportional control valve that outputs to the flow control valve as one pilot pressure to move the spool in one of the predetermined directions, and pressure oil supplied from the pressure source is used as a primary pressure And a proportional proportional second electromagnetic proportional control valve for performing pressure reduction control to a second output pressure according to the input current, and a set pressure supplied from the pressure source And any one of the second output pressure outputted from the second electromagnetic proportional control valve as the second pilot pressure, which is the other of the two pilot pressures, to the flow control valve to cause the spool to A switching valve for moving the other in the predetermined direction, an oil passage branched from a passage between the first electromagnetic proportional control valve and the flow control valve and connected to the switching valve, and a first direction and a second direction different from each other
  • the first electromagnetic proportional control valve and the second electromagnetic proportional control valve operate normally, and the first electromagnetic directional control valve operates in the first direction.
  • the first pilot pressure and the second output pressure are input to the switching valve so as to be opposed to each other, and the switching valve has a predetermined difference obtained by subtracting the second output pressure from the first pilot pressure.
  • the set pressure is output as the second pilot pressure to the flow control valve, and when the difference is less than the predetermined pressure, the second output pressure is the second pilot pressure.
  • control unit generates a fault in the second electromagnetic proportional control valve or its wiring path such that the second output pressure is maintained at zero even if the operating device is operated in the second direction. If it is determined that The first output pressure corresponding to the second direction operation amount of the operating device at the predetermined pressure or more by supplying power to the first electromagnetic proportional control valve from the first electromagnetic proportional control valve as the first pilot pressure It makes it output to the said flow control valve and the said switching valve.
  • the second output pressure corresponding to the amount of operation of the operating device is output.
  • Ru On the other hand, if there is no output from the first solenoid proportional control valve, the difference between the first pilot pressure and the second output pressure becomes equal to or less than the predetermined pressure, and the second output pressure becomes the second pilot pressure from the switching valve to the flow control valve Output to
  • the spool of the flow control valve moves in the other direction to the position corresponding to the second output pressure, and the opening degree between the main pump and the hydraulic actuator corresponds to the second output pressure.
  • the hydraulic fluid of the flow rate according to the operation amount of the operating device can be flowed to the hydraulic actuator, and the hydraulic actuator can be moved at a speed according to the operation amount of the operating device.
  • the control unit when the operating device is operated in the second direction, the control unit does not perform the second electromagnetic proportional control valve but the first electromagnetic proportional control
  • the valve is energized to cause the first electromagnetic proportional control valve to output a first output pressure equal to or higher than a predetermined pressure.
  • the first pilot pressure becomes equal to or higher than the predetermined pressure
  • the set pressure is output from the switching valve to the flow control valve as the second pilot pressure. That is, two pilot pressures opposing each other act on the spool.
  • the first pilot pressure is controlled to be equal to or lower than the set pressure
  • the second pilot pressure is equal to the set pressure.
  • the two pilot pressures act on the spool to move the spool in the other direction and to a position according to the difference. Therefore, the difference between the two pilot pressures can be adjusted by adjusting the first output pressure according to the amount of operation of the operating device, and the spool is operated even if a failure occurs in the wiring path of the second electromagnetic proportional control valve. It can be moved to the position according to the second direction operation amount of the device. That is, as in the case where a fault occurs in the wiring path of the electromagnetic proportional control valve, the second electromagnetic proportional control valve has a fault in which the output pressure from the second electromagnetic proportional control valve is maintained at zero. In this case, hydraulic oil at a flow rate corresponding to the second direction operation amount of the operating device can be flowed to the hydraulic actuator, and the hydraulic actuator can be moved at a speed according to the second direction operation amount of the operating device.
  • the control unit When the operating device is operated in the first direction, the control unit generates a current corresponding to the amount of operation of the operating device, regardless of the presence or absence of a failure in the second electromagnetic proportional control valve or its wiring path. Output to proportional control valve. Then, the first output pressure of the pressure according to the operation amount of the operating device is output as the first pilot pressure from the first electromagnetic proportional control valve to the flow control valve, and in the first direction in which the operating device is operated The spool moves to a position according to the amount of operation. As a result, hydraulic oil at a flow rate corresponding to the first direction operation amount of the operating device can be flowed to the hydraulic actuator, and the hydraulic actuator can be moved at a speed according to the first direction operation amount of the operating device.
  • the stroke of the spool in one of the predetermined directions is made.
  • the amount may be configured to be maximum, and the switching valve may be configured such that the predetermined pressure is higher than the specified pressure.
  • the prescribed pressure is set lower than the prescribed pressure, so even if the second electromagnetic proportional control valve or its wiring path is broken, even if the first pilot pressure is boosted to the prescribed pressure.
  • the set pressure is not output as the second pilot pressure. Therefore, even in a state where the second electromagnetic proportional control valve or its wiring path is broken, the spool can be made to travel in one direction in the predetermined direction to the maximum stroke amount. That is, in the state where the second electromagnetic proportional control valve or the wiring path thereof is broken, it is possible to suppress the deterioration of the function of the hydraulic drive when moving the spool in one direction by the first pilot pressure.
  • either one of the first output pressure output from the first electromagnetic proportional control valve and the set pressure maintained constant by the pressure source is used as the first pilot pressure in the flow rate control valve.
  • the first switching valve is further provided, and the second switching pressure is input to the first switching valve so that the second pilot pressure and the first output pressure oppose each other, and the first switching valve is the second pilot.
  • the set pressure is output as the first pilot pressure, and the first difference is less than the first predetermined pressure
  • the first output pressure is output as the first pilot pressure
  • the first pilot pressure and the second output pressure are input to the second switching valve, which is the switching valve, so as to oppose each other
  • the second switching valve is If the second difference which is the difference obtained by subtracting the second output pressure from the one pilot pressure is equal to or greater than a second predetermined pressure which is a predetermined pressure, the set pressure is output to the flow control valve as the second pilot pressure If the second difference is less than the second predetermined pressure, the second output pressure is output as the second pilot pressure to the flow control valve, and the control unit causes the controller to operate in the first direction.
  • the second electromagnetic proportional control valve is energized.
  • the second output pressure corresponding to the first predetermined pressure or more and corresponding to the first direction operation amount of the operating device is the second pilot pressure, and the second electromagnetic proportional control valve controls the flow control valve and the second control pressure. Even when switching valve output There.
  • the operation amount of the operation device is used regardless of whether the operation in the first direction or the second direction is performed on the operation device. It is possible to flow the hydraulic fluid at a different flow rate to the hydraulic actuator, and move the hydraulic actuator at a speed according to the operation amount of the operating device.
  • the spool has the first pilot pressure greater than the second pilot pressure, and the differential pressure between the two pilot pressures reaches a predetermined first prescribed pressure in one of the predetermined directions.
  • the second pilot pressure is larger than the first pilot pressure, and the differential pressure between the two pilot pressures reaches a second predetermined pressure defined in advance, the stroke amount in the other direction in the predetermined direction Is configured to be maximum
  • the first switching valve is configured such that the first predetermined pressure is higher than the first prescribed pressure
  • the second switching valve is configured to have the second predetermined pressure be the second predetermined pressure. It may be configured to be greater than 2 specified pressure.
  • the first prescribed pressure is set lower than the first prescribed pressure
  • setting is made even if the second pilot pressure is boosted to the prescribed pressure in a state in which the first electromagnetic proportional control valve can not be energized. Pressure is not output as the first pilot pressure. Therefore, even in a state where the first electromagnetic proportional control valve or its wiring path is broken, the spool can be made to stroke in the other direction to the maximum stroke amount. That is, in the state where the first electromagnetic proportional control valve or its wiring path is broken, it is possible to suppress the deterioration of the function of the hydraulic drive system when moving the spool to the other side in the predetermined direction.
  • the spool is directed in the other direction in the other direction also in the state where the second electromagnetic proportional control valve or its wiring path is broken. Stroke to the maximum stroke amount. That is, when the spool is moved in one direction, it is possible to suppress the deterioration of the function of the hydraulic drive system.
  • the spool may be located at a neutral position for interrupting between the main pump and the hydraulic actuator when the differential pressure between the two pilot pressures is zero.
  • the second electromagnetic proportional control valve when the second electromagnetic proportional control valve sticks out in a state where the secondary pressure port is in communication with the primary pressure port and becomes uncontrollable, the second electromagnetic proportional control valve has the same pressure as the set pressure.
  • the second output pressure is to be output.
  • a second output pressure equal to the set pressure as the second pilot pressure is output from the second switching valve to the flow rate control valve.
  • the first switching valve the second output pressure equal to the set pressure is input as the second pilot pressure, whereby the first switch valve outputs the set pressure as the first pilot pressure to the flow rate control valve It will be.
  • first pilot pressure and the second pilot pressure of the same pressure act on the spool of the flow control valve so as to oppose each other, and the spool is held at the neutral position.
  • hydraulic fluid can be prevented from being guided to the hydraulic actuator to perform an undesired movement, and fail safe can be achieved.
  • a hydraulic drive system includes the above-described hydraulic drive device, a main pump that discharges hydraulic oil supplied to the hydraulic actuator, and a sub pump that constitutes the pressure source.
  • the hydraulic actuator can be operated according to the operation of the operating device even if a failure occurs such that the output pressure from the electromagnetic proportional control valve is maintained at zero.
  • various attachments are provided, which are moved by a hydraulic actuator 2 such as a hydraulic cylinder or a hydraulic motor.
  • the hydraulic drive system 1 is provided to move the hydraulic actuator 2.
  • the hydraulic drive system 1 supplies hydraulic fluid to a hydraulic actuator 2 (a hydraulic cylinder in the present embodiment) to drive the hydraulic actuator 2.
  • a hydraulic actuator 2 a hydraulic cylinder in the present embodiment
  • two or more hydraulic actuators may be connected to the hydraulic drive system 1.
  • the configuration of the hydraulic drive system 1 will be described in more detail.
  • the hydraulic drive system 1 includes a main pump 11, a tank 12, an engine E, a sub pump 13, and a hydraulic drive device 14.
  • the main pump 11 is a variable displacement swash plate pump
  • the tank 12 is connected to the suction port 11a
  • the hydraulic drive 14 is connected to the discharge port 11b.
  • the main pump 11 is connected to the engine E, and the engine E is configured to rotate the rotation shaft 11 c of the main pump 11 at an arbitrary predetermined rotational speed.
  • the main pump 11 has a swash plate 11 d capable of changing the tilt angle, and the discharge displacement of the main pump 11 can be adjusted by changing the tilt angle of the swash plate 11 d.
  • a regulator 15 is provided on the swash plate 11 d of the main pump 11 so that the tilt angle of the swash plate 11 d can be changed by the regulator 15.
  • the main pump 11 configured as described above discharges the hydraulic fluid by rotating the rotation shaft 11c of the engine E, and the flow rate of the hydraulic fluid to be discharged (ie, the discharge flow rate) is oblique.
  • the flow rate corresponds to the tilt angle of the plate 11 d and the rotational speed of the engine E.
  • the rotating shaft 13a of the sub pump 13 is further rotated integrally with the rotating shaft 11c on the rotating shaft 11c of the main pump 11 having such a function.
  • the sub pump 13 is connected in series to the main pump 11.
  • the sub pump 13 may be connected in parallel, and may be connected on the opposite side of the engine E to the main pump 11. It is also good.
  • the sub pump 13 connected in this manner is a fixed displacement type pump, the tank 12 is connected to the suction port 13 b, and the sub passage 20 of the hydraulic drive device 14 is connected to the discharge port 13 c.
  • the rotation shaft 13a of the sub pump 13 is connected to the engine E via the rotation shaft 11c, and rotates at a rotational speed corresponding to the rotational speed of the engine E.
  • the sub pump 13 discharges pressure oil to the sub passage 20 by rotating, and the sub passage 20 is provided with a relief valve 28 to keep the pressure of the pressure oil constant.
  • the relief valve 28 is disposed to communicate the sub passage 20 with the tank 12.
  • the relief valve 28 discharges the hydraulic fluid flowing through the sub passage 20 when the hydraulic pressure of the sub passage 20 exceeds a predetermined set pressure, and maintains the sub pump discharge pressure pp of the sub pump 13 at the set pressure (that is, constant pressure). .
  • the hydraulic drive unit 14 is supplied with pressure oil at a constant pressure.
  • the hydraulic drive unit 14 operates using the sub pump discharge pressure pp from the sub pump 13 and switches to which path of the hydraulic actuator 2 the hydraulic oil discharged from the main pump 11 is to be led or adjusts the flow rate By doing this, the movement of the hydraulic actuator 2 is controlled. More specifically, the hydraulic drive device 14 includes a flow control valve 21, a first electromagnetic proportional control valve 22R, a second electromagnetic proportional control valve 22L, a first switching valve 24R, and a second switching valve 24L. A control unit 26 and an operating device 27 are provided.
  • the flow control valve 21 is connected to the main pump 11 and the hydraulic actuator 2 so as to control the direction and flow rate of hydraulic fluid flowing from the main pump 11 to the hydraulic actuator 2. More specifically, the hydraulic actuator 2 has two ports 2a and 2b, and the flow control valve 21 is connected to the two ports 2a and 2b. Further, the flow control valve 21 is connected to the discharge port 11b of the main pump 11 and the tank 12, and has a spool 21a to switch the connection state of these. That is, the flow control valve 21 can adjust the flow direction of the hydraulic fluid and the opening degree of the flow control valve 21 by moving the spool 21 a.
  • the spool 21a can be moved from one direction and the other in a predetermined direction, ie, from the neutral position M0 to the first offset position M1 and the second offset position M2, respectively. Between the hydraulic actuator 2 and the hydraulic actuator 2 and between the hydraulic actuator 2 and the tank 12 so that hydraulic fluid does not flow between them.
  • the discharge port 11 b of the main pump 11 and the first port (in the present embodiment, the head side port) 2 a of the hydraulic actuator 2 are connected, and the second port of the hydraulic actuator 2 (In the present embodiment, the rod side port) 2b and the tank 12 are connected.
  • the discharge port 11b and the first port 2a are connected at an opening degree according to the position of the spool 21a, and hydraulic oil of a flow rate according to the position (stroke amount) of the spool 21a is guided to the first port 2a .
  • the hydraulic actuator 2 extends at a speed corresponding to the position of the spool 21a.
  • the discharge port 11b of the main pump 11 and the second port 2b of the hydraulic actuator 2 are connected, and the first port 2a of the hydraulic actuator 2 and the tank 12 are connected Be done.
  • the discharge port 11b and the second port 2b are connected at an opening degree corresponding to the position of the spool 21a, and hydraulic oil having a flow rate corresponding to the position of the spool 21a is guided to the second port 2b.
  • the hydraulic actuator 2 contracts at a speed corresponding to the position of the spool 21a.
  • the flow control valve 21 configured in this manner further includes two springs 31L and 31R, and the two springs 31L and 31R bias the spool 21a so as to oppose each other so that the spool 21a is in the neutral position. It is maintained at M0.
  • the flow control valve 21 has two pilot ports 21R and 21L, and the pilot pressures piR and piL are respectively input to the flow control valve 21.
  • the first pilot port 21R is formed to act on the spool 21a so that the first pilot pressure piR inputted thereto opposes the first spring 31L, and the spool 21a is operated by the first pilot pressure piR. It is pressed toward the first offset position M1.
  • the second pilot port 21L is formed to act on the spool 21a so that the second pilot pressure piL input thereto opposes the second spring 31R, and the spool 21a is a second pilot pressure. It is pushed toward the second offset position M2 by piL. Therefore, the spool 21a moves to a position corresponding to the differential pressure between the two pilot pressures piR and piL acting thereon, and hydraulic fluid in a direction and flow rate corresponding to the position flows to the hydraulic actuator 2 ing.
  • the two pilot pressures piR and piL thus input are generated from the sub pump discharge pressure pp discharged from the sub pump 13, and the sub pump 20 is connected to the sub pump 13 to generate two pilot pressures piR and piL.
  • the two electromagnetic proportional control valves 22R and 22L are connected in parallel via each other.
  • the primary pressure port is selectively connected to either the sub pump 13 or the tank 12, and the secondary pressure port is the first It is connected to the switching valve 24R.
  • the first solenoid proportional control valve 22R can be supplied with current (that is, the first command signal is input) to the solenoid part 22Ra, and is opened according to the current supplied to the solenoid part 22Ra. It is designed to switch degrees.
  • the first electromagnetic proportional control valve 22R is a direct proportional electromagnetic proportional control valve, and the sub pump 13 and the secondary pressure port are connected by supplying a current to the solenoid section 22Ra, and the sub pump 13 and the secondary pressure port Is opened at an opening degree corresponding to the current flowing to the solenoid portion 22Ra.
  • the sub pump 13 and the valve secondary pressure port are shut off, and the valve secondary pressure port is connected to the tank 12.
  • the first electromagnetic proportional control valve 22R configured in this manner controls the pressure of the sub pump discharge pressure pp to a pressure (first output pressure psR) according to the current flowing to the solenoid section 22Ra, and outputs it to the secondary pressure port Do.
  • the second electromagnetic proportional control valve 22L which is the other of the two electromagnetic proportional control valves 22R and 22L, has the same structure as the first electromagnetic proportional control valve 22R, and the primary pressure port is the sub pump 13 and the tank 12 And the secondary pressure port is connected to the second switching valve 24L. That is, the second electromagnetic proportional control valve 22L is a direct proportional electromagnetic proportional control valve, and the sub pump 13 and the secondary pressure port are connected by supplying a current to the solenoid unit 22La, and the sub pump 13 and the secondary pressure port Is opened at an opening degree corresponding to the current flowing to the solenoid portion 22La.
  • the second electromagnetic proportional control valve 22L configured in this way controls the sub pump discharge pressure pp to a pressure (that is, the second output pressure psL) corresponding to the current flowing to the solenoid section 22La, and the secondary pressure port Output to
  • the two electromagnetic proportional control valves 22R and 22L configured as described above have the following functions. That is, the output pressures psR and psL output from the two electromagnetic proportional control valves 22R and 22L are input to the two switching valves 24R and 24L, respectively.
  • the sub pump 13 and the first pilot port 21R of the flow control valve 21 are connected to the first switching valve 24R, and the second switching valve 24L is connected to the second switching valve 24L.
  • the sub pump 13 and the second pilot port 21L of the flow control valve 21 are connected.
  • the first switching valve 24R and the second switching valve 24L thus connected are configured as follows.
  • the first switching valve 24R is connected to the first pilot port 21R of the flow control valve 21 via the first pilot passage 23R, and switches the first pilot pressure piR input to the flow control valve 21. That is, the first switching valve 24R has the spool 24Ra movable between the first position M1R and the second position M2R, and the first electromagnetic proportional control is performed with the spool 24Ra positioned at the first position M1R.
  • the secondary port of the valve 22R and the first pilot port 21R are connected.
  • the first output pressure psR which is the secondary pressure of the first electromagnetic proportional control valve 22R, is output to the flow control valve 21 as the first pilot pressure piR.
  • the second switching valve 24L is connected to the second pilot port 21L of the flow control valve 21 through the second pilot passage 23L, and switches the second pilot pressure piL input to the flow control valve 21.
  • the second switching valve 24L has a spool 24La switchable between the first position M1L and the second position M2L, and the second electromagnetic proportional control is performed with the spool 24La positioned at the first position M1L.
  • the secondary port of the valve 22L and the second pilot port 21L are connected.
  • the second output pressure psL of the second electromagnetic proportional control valve 22L is output to the flow control valve 21 as the first pilot pressure piL.
  • the sub pump 13 and the second pilot port 21L are connected, and the sub pump discharge pressure pp is output to the flow control valve 21 as the second pilot pressure piL.
  • first pilot passage 23R is connected to the first oil passage 25R so as to branch along the way, and the first oil passage 25R is connected to the second switching valve 24L.
  • the first oil passage 25R applies a first pilot pressure piR to the spool 24La of the second switching valve 24L.
  • the second output pressure psL output from the second electromagnetic proportional control valve 22L acts on the spool 24La of the second switching valve 24L in a direction that opposes the first pilot pressure piR. Therefore, the spool 24La of the second switching valve 24L moves in accordance with the differential pressure between the second output pressure psL and the first pilot pressure piR, and switches its position.
  • the spool 24La of the second switching valve 24L is provided with a spring 24Lb that applies a biasing force in a direction that opposes the first pilot pressure piR. Therefore, when the differential pressure obtained by subtracting the second output pressure psL from the first pilot pressure piR is less than the second predetermined pressure ps2, the spool 24La is located at the first position M1L and the second output pressure psL Are output to the flow control valve 21 as the second pilot pressure piL. On the other hand, when the difference is equal to or greater than the second predetermined pressure ps2, the spool 24La is positioned at the second position M2L. As a result, the sub pump discharge pressure pp is output to the flow control valve 21 as the second pilot pressure piL.
  • the second predetermined pressure ps2 is a pressure determined according to the biasing force of the spring 24Lb that biases the spool 24La, and is set as follows. That is, the second predetermined pressure ps2 is set to a pressure that is larger than the pressure pm1 required to cause the spool 21a to stroke to the maximum stroke amount by causing the first pilot pressure piR to act on the spool 21a and smaller than the sub pump discharge pressure pp There is. In the present embodiment, the second predetermined pressure ps2 is set to the same pressure as the first predetermined pressure ps1.
  • the second pilot passage 23L is connected to the second oil passage 25L so as to branch along the way, and the second oil passage 25L is connected to the first switching valve 24R.
  • the second oil passage 25L applies a second pilot pressure piL to the spool 24Ra of the first switching valve 24R.
  • the first output pressure psR output from the first electromagnetic proportional control valve 22R acts on the spool 24Ra of the first switching valve 24R in a direction that opposes the second pilot pressure piL. Therefore, the spool 24Ra of the first switching valve 24R moves in accordance with the differential pressure between the first output pressure psR and the second pilot pressure piL, and switches its position.
  • the spool 24Ra of the first switching valve 24R is provided with a spring 24Rb that applies a biasing force in a direction that opposes the second pilot pressure piL. Therefore, the spool 24Ra is positioned at the first position M1R if the differential pressure obtained by subtracting the first output pressure psR from the second pilot pressure piL is less than the first predetermined pressure ps1, and the first output pressure psR The first pilot pressure piR is output to the flow control valve 21. On the other hand, when the difference is equal to or more than the first predetermined pressure, the spool 24Ra is located at the second position M2R. As a result, the sub pump discharge pressure pp is output to the flow control valve 21 as the first pilot pressure piR.
  • the first predetermined pressure ps1 is a pressure determined according to the biasing force of the spring 24Rb that biases the spool 24Ra, and is set as follows. That is, the first predetermined pressure ps1 is set to a pressure which is larger than the pressure pm2 necessary for causing the second pilot pressure piL to act on the spool 21a and causing the spool 21a to stroke to the maximum stroke amount and smaller than the discharge pressure pp of the sub pump 13. (See the graph in Figure 2). In the graph of FIG. 2, the horizontal axis represents the pilot pressure piR, piL, and the vertical axis represents the stroke amount of the spool 24Ra.
  • the hydraulic drive device 14 configured in this way is capable of supplying current to the two electromagnetic proportional control valves 22R and 22L, and the spool of the flow control valve 21 is generated by causing the current to flow.
  • the position of 21a is to be controlled.
  • a control unit 26 is electrically connected to the two electromagnetic proportional control valves 22R, 22L configured in this way so as to supply current to them and control their movement, and the control unit 26 has an operating device 27 are electrically connected.
  • the operating device 27 has an operating lever 27a, and the operating lever 27a is configured to be operable (more specifically, tiltable) in mutually opposing first direction A1 and second direction A2.
  • the operating device 27 is also configured to output to the control unit 26 an operating command according to the operating direction and the operating amount (i.e., the amount of tilting) of the operating lever 27a.
  • the control unit 26 is electrically connected to the first electromagnetic proportional control valve 22R, the second electromagnetic proportional control valve 22L, and the regulator 15, and controls these movements in response to an operation command from the operating device 27. ing. That is, the control unit 26 operates the regulator 15 to adjust the tilt angle of the swash plate 11 d to a tilt angle according to the amount of operation of the control lever 27 a. Further, the control unit 26 controls either of the two electromagnetic proportional control valves 22R and 22L according to the operation direction of the control lever 27a, and the flow rate according to the operation amount in the direction according to the operation direction of the control lever 27a. Is supplied to the hydraulic actuator 2.
  • the control unit 26 also operates as follows to detect a failure of the first electromagnetic proportional control valve 22R and the second electromagnetic proportional control valve 22L. That is, the control unit 26 detects the value of the current flowing to the first electromagnetic proportional control valve 22R and the second electromagnetic proportional control valve 22L, and the wiring paths of the electromagnetic proportional control valves 22R and 22L (ie, the first and second electromagnetic For each of the proportional control valves 22R and 22L, the conduction state of the harness connected to the control unit 26, the connection portion, and the solenoid portions 22Ra and 22La) is detected, and the conduction failure in each wiring path (ie, disconnection in the wiring path and Detection of a short).
  • control unit 26 detects the discharge pressure p of the main pump 11 using a pressure sensor (not shown), and the relationship between the detected discharge pressure p and the operation amount of the control lever 27a causes the first electromagnetic proportional control valve 22R and 2) It is possible to detect whether or not the valve element of the electromagnetic proportional control valve 22L operates according to the supplied current value (that is, the presence or absence of the occurrence of the stick).
  • the hydraulic drive system 1 configured as described above can supply the hydraulic actuator 2 with hydraulic fluid in a direction and at a flow rate corresponding to the amount of operation of the control lever 27a. That is, the hydraulic actuator 2 can be driven in the direction according to the amount of operation of the control lever 27a and at the speed.
  • the operation lever 27a is operated in the second direction A2
  • an operation command according to the operated direction and the operation amount of the operation lever 27a is output from the operation device 27 to the control unit 26.
  • the control unit 26 supplies a current corresponding to the operation command to the solenoid section 22La of the second electromagnetic proportional control valve 22L.
  • the second output pressure psL corresponding to the operation amount of the control lever 27a is output from the second electromagnetic proportional control valve 22L to the second switching valve 24L.
  • the spool 24La changes its position according to the differential pressure between the first output pressure psR and the second pilot pressure piL.
  • the first pilot pressure piR fluctuates according to the first output pressure psR of the first electromagnetic proportional control valve 22R and the position of the spool 24Ra of the first switching valve 24R.
  • the first output pressure psR is basically the tank pressure
  • the position of the spool 24Ra of the first switching valve 24R is the first pilot pressure piL It depends on whether or not the predetermined pressure ps1 or more.
  • the spool 21a of the flow control valve 21 is configured to stroke up to the maximum stroke amount when the second pilot pressure piL reaches the pressure pm2. Therefore, the control unit 26 is controlled such that the second output pressure psL is in the range of 0 ⁇ psL ⁇ pm2, except in the case described later (ie, failure of the second electromagnetic proportional control valve 22L).
  • the second pilot pressure piL is controlled within the range of 0 ⁇ piL ⁇ pm2. That is, the second pilot pressure piL is basically less than the first predetermined pressure ps1, the spool 24Ra of the first switching valve 24R is located at the first position M1R, and the first pilot pressure piR is the tank pressure. It is maintained.
  • the differential pressure obtained by subtracting the second output pressure psL from the first pilot pressure piR becomes less than the second predetermined pressure ps2, and the spool 24La of the second switching valve 24L also becomes Located at the first position M1L.
  • the second output pressure psL is output as the second pilot pressure piL from the second switching valve 24L to the flow control valve 21, and the spool 21a of the flow control valve 21 corresponds to the second pilot pressure piL, that is, the operation lever Move to the position according to the operation amount of 27a.
  • the hydraulic actuator 2 By moving, the hydraulic oil having a flow rate corresponding to the amount of operation of the control lever 27a is guided to the direction in which the control lever 27a is operated, that is, the second port 2b of the hydraulic actuator 2.
  • the hydraulic actuator 2 can be contracted at a speed corresponding to the amount of operation of the control lever 27a.
  • the operation when the operation lever 27a is operated in the first direction A1 is the same as the operation when operated in the second direction A2 and thus will not be described in detail, but the operation may be performed when the operation lever 27a is operated in the first direction A1.
  • an operation command is output from the operating device 27 to the control unit 26.
  • the control unit 26 supplies a current corresponding to the operation command to the solenoid section 22Ra of the first electromagnetic proportional control valve 22R.
  • the first output pressure psR is output to the flow control valve 21 via the first switching valve 24R, that is, the first output pressure psR is input to the flow control valve 21 as a first pilot pressure piR.
  • the hydraulic drive system 1 that operates in this manner operates as follows when any of the first electromagnetic proportional control valve 22R and the second electromagnetic proportional control valve 22L fails.
  • the second output pressure psL of the second electromagnetic proportional control valve 22L (or the first output pressure psR of the first electromagnetic proportional control valve 22R) is maintained at zero due to the electrification failure and the stick of the valve body.
  • the second output pressure psL of the second electromagnetic proportional control valve 22L (or the first output pressure psR of the first electromagnetic proportional control valve 22R) is maintained at zero, the second electromagnetic proportional control
  • a failure that is, disconnection or short circuit
  • the control unit 26 detects the value of the current when the second electromagnetic proportional control valve 22L is energized. Therefore, the command current corresponding to the operation command (ie, the current value instructed by the control unit) and the value of the actually detected current (ie, the current value actually flowing to the second electromagnetic proportional control valve) are If different, for example, if it is attempted to energize the second electromagnetic proportional control valve 22L and the value of the current is not detected, the control unit 26 determines that the wiring path in the second electromagnetic proportional control valve 22L has a fault. .
  • the second switching valve 24L and the tank 12 are in communication regardless of the operation of the control lever 27a because the second solenoid proportional control valve 22L is a direct proportional type solenoid valve. It is maintained.
  • the first output pressure psR can be controlled within the range of 0 ⁇ psR ⁇ pm1 when the first electromagnetic proportional control valve 22R operates normally, the spool 24La of the second switching valve 24L is the first It can be stopped at position M1L. That is, the second pilot pressure piL is maintained at the tank pressure.
  • the control unit 26 when the control lever 27a is operated in the first direction A1, the control unit 26 is in the range of 0 ⁇ psR ⁇ pm1 as in the case where no failure occurs in the wiring path in the second electromagnetic proportional control valve 22L. It is possible to control the first electromagnetic proportional control valve 22R and extend the hydraulic actuator 2 at a speed according to the operation amount of the control lever 27a (the effective pilot range (0 ⁇ psR ⁇ pm1 in the graph of FIG. 3)). reference).
  • the horizontal axis indicates the output pressure psR
  • the upper side of the vertical axis indicates the first pilot pressure piR
  • the lower side of the vertical axis indicates the second pilot pressure piL.
  • the control unit 26 uses the first electromagnetic proportional control valve 22R to perform hydraulic pressure as follows.
  • the actuator 2 is contracted. That is, when the operation lever 27a is operated in the second direction A2 and the operation signal is received from the operation device 27, the control unit 26 performs the first electromagnetic proportional control so that the first output pressure psR becomes equal to or higher than the second predetermined pressure ps2. Control the operation of the valve 22R.
  • the first output pressure psR equal to or higher than the second predetermined pressure ps2 is output from the first switching valve 24R as the first pilot pressure piR, and the first pilot pressure piR becomes equal to or higher than the second predetermined pressure ps2.
  • the spool 24La of the second switching valve 24L moves to the second position M2L, and the second switching valve 24L causes the sub pump 13 and the flow control valve 21 to The second pilot port 21L is connected. That is, the sub pump discharge pressure pp of the sub pump 13 is output from the second switching valve 24L as the second pilot pressure piL.
  • the second pilot pressure piL larger than the first pilot pressure piR can be applied to the spool 21a of the flow control valve 21 so as to withstand the first pilot pressure piR, and the spool 21a can be operated based on the differential pressure.
  • control unit 26 controls the output pressure psR in accordance with the amount of operation of the control lever 27a as shown in the graph of FIG. 3, and hydraulic oil of a flow rate corresponding to the amount of operation of the control lever 27a flows to the hydraulic actuator 2.
  • the spool 21a is moved to a position corresponding to the amount of operation of the control lever 27a, that is, toward the second offset position M2 by adjusting (the two-dot chain line in FIG. 3).
  • the output pressure psL of the pressure value px is output from the second electromagnetic proportional control valve 22L with respect to the operation amount of the control lever 27a.
  • the control unit 26 moves the spool 21a by the same stroke amount as the operation amount described above, so that the differential pressure between the two pilot pressures piL and piR (more detailed The output pressure psR adjusted so that the differential pressure obtained by subtracting the first pilot pressure piR from the second pilot pressure piL becomes the pressure value px is output from the first electromagnetic proportional control valve 22R.
  • control unit 26 adjusts the output pressure psR so that the difference from the sub pump discharge pressure pp becomes the pressure value px.
  • the hydraulic actuator 2 can be contracted at a speed according to the amount of operation of the control lever 27a.
  • the operation lever 27a is operated in the second direction A2 (ie, The relationship between the first output pressure psR and the position of the spool 21a is in inverse proportion to each other. That is, the spool 21a is at the neutral position in a state where the control unit 26 energizes the first electromagnetic proportional control valve 22R and the opening degree is maximized (ie, the first output pressure psR becomes equal to the sub pump discharge pressure pp).
  • the amount of stroke in the direction to the second offset position M2 of the spool 21a is increased by reducing the current supplied to the first electromagnetic proportional control valve 22R by the control unit 26 to reduce the opening degree,
  • the stroke amount is maximized when the first output pressure psR becomes equal to the second predetermined pressure ps2.
  • the hydraulic drive system 1 of this embodiment is provided with the function mentioned above as a fail safe function to the last, it is comprised as follows. That is, in the hydraulic drive system 1 according to the present embodiment, the second pilot pressure piL can be varied in the range of 0 ⁇ piL ⁇ pp ⁇ ps2 when the second electromagnetic proportional control valve 22L fails to be energized. is there. Therefore, the sub pump discharge pressure pp and the second predetermined pressure ps2 are set so that the value obtained by subtracting the second predetermined pressure ps2 from the sub pump discharge pressure pp becomes smaller than the above-described pressure pm2.
  • the second electromagnetic proportional control valve 22L breaks down, the maximum stroke amount of the spool 21a can be limited, and the speed with respect to the operation amount when the operation amount of the operation lever 27a is operated beyond the predetermined amount Can be limited to constant speed without proportion. Also, in this way, the driver can be notified of the failure of the proportional valve without adding any parts.
  • the value obtained by subtracting the second predetermined pressure ps2 from the sub pump discharge pressure pp may be larger than the pressure pm2. In that case, it is possible to configure the hydraulic drive system 1 whose speed is not limited with respect to the operation amount of the control lever 27a even at the time of failure.
  • the hydraulic drive system 1 outputs the first output pressure psR at or above the first specified pressure pm1 that can not be effectively used even if the first electromagnetic proportional control valve 22R does not have a fault and outputs it in a normal state.
  • the first electromagnetic proportional control valve 22R enables the hydraulic actuator 2 to be contracted as well as extended. Therefore, in the hydraulic drive system 1, even when a failure occurs in the wiring path in the second electromagnetic proportional control valve 22L, failsafe can be achieved, and the highly reliable hydraulic drive system 1 can be realized.
  • the cost increase of the hydraulic drive system 1 can be suppressed, achieving fail safe.
  • the first pilot pressure piR is prescribed first in a state where energization of the second electromagnetic proportional control valve 22L is defective. Even if the pressure is increased to the pressure pm1, the sub pump discharge pressure pp is not output as the second pilot pressure piL. Therefore, even in the state where the second electromagnetic proportional control valve 22L is in the state of the electrification failure, the spool 21a can be made to stroke toward the first offset position M1 up to the maximum stroke amount. That is, in the state where the second electromagnetic proportional control valve 22L is in the state of energization failure, it is possible to suppress the decrease in the function of the hydraulic drive device 14 when moving the spool 21a to the first offset position M1.
  • the second output pressure psL of the second electromagnetic proportional control valve 22L (or the first output pressure psR of the first electromagnetic proportional control valve 22R) is maintained at zero as a fault such that the output side and the tank 12
  • the hydraulic actuator 2 can be contracted according to the amount of operation of the control lever 27a by executing the same control as when the second electromagnetic proportional control valve 22L can not be energized as described above. .
  • the second output pressure psL of the second electromagnetic proportional control valve 22L is the sub pump discharge It becomes equal to the pressure pp. Therefore, the spool 24La of the second switching valve 24L is located at the first position M1L regardless of the magnitude of the first pilot pressure piR, and the second output pressure psL equal to the sub pump discharge pressure pp is the flow rate as the second pilot pressure piL. It is output to the control valve 21.
  • the second output pressure psL equal to the sub pump discharge pressure pp is output as the second pilot pressure piL. Move to 2 position M2R.
  • the sub pump discharge pressure pp is output to the flow control valve 21 as the first pilot pressure piR.
  • the first pilot pressure piR and the second pilot pressure piL of the same pressure act on the spool 21a of the flow control valve 21 to oppose each other, and the spool 21a is held at the neutral position M0.
  • hydraulic fluid can be prevented from being guided to the hydraulic actuator 2 to perform an undesired movement, and fail safe can be achieved.
  • the hydraulic drive system 1 of this embodiment is connected to only one hydraulic actuator 2, the hydraulic actuator connected as described above is not limited to one.
  • the hydraulic drive system 1 may be connected to two or more hydraulic actuators, and may have a plurality of flow control valves 21 accordingly.
  • the plurality of flow control valves 21 are connected, for example, in parallel to the main pump 11, and each of the flow control valves 21 is provided with a first electromagnetic proportional control valve 22R, a second electromagnetic proportional control valve 22L, A first switching valve 24R and a second switching valve 24L are provided respectively.
  • the hydraulic drive system provided with the plurality of flow control valves 21 also achieves the same function as the case described above.
  • the switch valves 24R and 24L are provided at any of the ports 21R and 21L of the flow control valve 21. However, it is not necessary to have both of them. Good.
  • the pressure source for supplying a constant set pressure is configured by the sub pump 13 and the relief valve 28, but such a configuration is not necessarily required.
  • a pressure source may be configured by the main pump 11 and the pressure reducing valve, and a predetermined set pressure may be supplied to the sub passage 20 from the main passage connecting the main pump 11 and the flow control valve 21 via the pressure reducing valve. .
  • the maximum speed of the hydraulic actuator 2 is limited after occurrence of a failure in the electromagnetic proportional control valves 22R and 22L, and the operation amount of the control lever 27a before and after the failure occurrence and the hydraulic actuator 2
  • the control unit 26 is configured such that the relationship with the speed of the vehicle does not change.
  • the control unit 26 does not necessarily have to be configured in this way. That is, when the operation amount of the operation lever 27a is maximized even after the failure occurs, the operation amount of the operation lever 27a and the speed of the hydraulic actuator 2 are set so that the hydraulic actuator 2 can be driven at the same maximum speed as before the failure occurrence.
  • the correspondence relationship may be changed.
  • the sub pump discharge pressure pp needs to be a pressure obtained by adding the second predetermined pressure pm2 to the first predetermined pressure ps1, and a pressure obtained by adding the first predetermined pressure pm1 to the second predetermined pressure ps2.
  • a hydraulic cylinder is employed as the hydraulic actuator 2, but the present invention is not necessarily limited to the hydraulic cylinder. That is, the hydraulic actuator 2 may be a hydraulic motor, as long as it operates by supplying hydraulic fluid such as hydraulic fluid.

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  • Physics & Mathematics (AREA)
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Abstract

Provided is a hydraulic drive device that makes it possible to operate a hydraulic actuator in accordance with operation of an operation device, even when there has been a failure in an electromagnetic proportional control valve or a wiring pathway thereof. A hydraulic drive system, wherein: a first pilot pressure and a second output pressure are inputted to a switch valve so as to resist one another; the switch valve outputs a set pressure to a flow rate control valve as a second pilot pressure if the difference obtained by subtracting the second output pressure from the first pilot pressure is a predetermined pressure or greater; the switch valve outputs the second output pressure as the second pilot pressure if the difference is less than the predetermined pressure; and if such a determination is made that a second electromagnetic proportional control valve or a wiring pathway thereof is experiencing a failure that causes the second output pressure to be zero even if the operation device is operated in a second direction, then a control unit powers a first electromagnetic proportional control valve and causes the same to output a first output pressure, which is at least the predetermined pressure and corresponds to a second direction operation amount of the operation device, as the first pilot pressure to the flow rate control valve and the switch valve.

Description

油圧駆動装置、及びそれを備える油圧駆動システムHydraulic drive system and hydraulic drive system provided with the same
　本発明は、メインポンプから油圧アクチュエータに作動油を流して油圧アクチュエータを駆動する油圧駆動装置、及びそれを備える油圧駆動装置システムに関する。 The present invention relates to a hydraulic drive unit that drives hydraulic actuators by flowing hydraulic fluid from a main pump to a hydraulic actuator, and a hydraulic drive system including the same.
　油圧アクチュエータは、メインポンプからの作動油によって駆動するようになっており、メインポンプはマルチコントロール弁と共に油圧駆動回路を構成している。油圧駆動回路では、マルチコントロール弁によってメインポンプから油圧アクチュエータに流れる作動油の方向及び流量が制御されており、これによって油圧アクチュエータの動きが制御されている。このような機能を有する油圧駆動回路の一例として、例えば特許文献１に記載されているような油圧駆動回路が知られている。 The hydraulic actuator is driven by hydraulic oil from the main pump, and the main pump constitutes a hydraulic drive circuit together with the multi-control valve. In the hydraulic drive circuit, the direction and flow rate of hydraulic fluid flowing from the main pump to the hydraulic actuator are controlled by the multi-control valve, whereby the movement of the hydraulic actuator is controlled. As an example of a hydraulic drive circuit having such a function, a hydraulic drive circuit as described in, for example, Patent Document 1 is known.
　特許文献１の油圧駆動回路では、マルチコントロール弁に入力されるパイロット圧を電磁比例制御弁によって制御するようになっている。即ち、操作レバーの操作量が制御装置に入力され、制御装置は、入力された操作量に応じたパイロット圧をマルチコントロール弁のスプールに与えるべく電磁比例制御弁の動きを制御する。これにより、操作量に応じた流量の作動油が油圧アクチュエータに導かれ、操作量に応じた速度で油圧アクチュエータを動かすことができる。 In the hydraulic drive circuit of Patent Document 1, the pilot pressure input to the multi-control valve is controlled by the electromagnetic proportional control valve. That is, the operation amount of the operation lever is input to the control device, and the control device controls the movement of the electromagnetic proportional control valve so as to apply the pilot pressure according to the input operation amount to the spool of the multi-control valve. As a result, hydraulic fluid having a flow rate corresponding to the amount of operation is guided to the hydraulic actuator, and the hydraulic actuator can be moved at a speed according to the amount of operation.
特開昭６４－６５０１号公報Japanese Patent Application Laid-Open No. 64-6501
　電磁比例制御弁は、以下のような故障が発生することが考えられる。即ち、電磁比例制御弁と制御装置とを繋ぐ信号線が断線する等のような配線経路に故障が生じる場合がある。この場合、操作レバーを操作しても電磁比例制御弁の一次圧側の通路と二次圧（出力）側の通路とが遮断された状態が継続し、電磁比例制御弁から出力圧がゼロのままとなる。また、電磁比例制御弁の弁体が電磁比例制御弁の一次圧側の通路と二次圧側の通路とを遮断する状態でスティックするような故障が生じる場合もあり、この場合も配線経路に故障が生じている場合と同様に、電磁比例制御弁から出力圧がゼロのままとなる。それ故、何れの場合においても、操作レバーが操作されてもマルチコントロール弁のスプールが中立位置に維持されるので、操作レバーを操作しても油圧アクチュエータが反応しない。しかし、このような故障が生じている場合においても、油圧アクチュエータを作動させることができるようにすることが望まれている。 The following problems may occur in the electromagnetic proportional control valve. That is, a failure may occur in the wiring path such as disconnection of a signal line connecting the electromagnetic proportional control valve and the control device. In this case, even if the control lever is operated, the primary pressure passage and the secondary pressure (output) passage of the electromagnetic proportional control valve continue to be blocked, and the output pressure from the electromagnetic proportional control valve remains zero. It becomes. In addition, a failure may occur such as sticking in a state in which the valve body of the electromagnetic proportional control valve shuts off the passage on the primary pressure side and the passage on the secondary pressure side of the electromagnetic proportional control valve. As is the case, the output pressure from the proportional solenoid valve remains zero. Therefore, in either case, even if the control lever is operated, the spool of the multi-control valve is maintained in the neutral position, so the hydraulic actuator does not respond even if the operation lever is operated. However, it is desirable to be able to operate the hydraulic actuator even when such a failure has occurred.
　そこで本発明は、電磁比例制御弁からの出力圧がゼロのままに維持されるような故障が生じても、操作装置の操作に応じて油圧アクチュエータを動作させることができる油圧駆動装置、及びそれを備える油圧駆動システムを提供することを目的としている。 Therefore, the present invention provides a hydraulic drive device capable of operating a hydraulic actuator according to the operation of the operating device even if a failure occurs such that the output pressure from the electromagnetic proportional control valve is maintained at zero. It is an object of the present invention to provide a hydraulic drive system comprising:
　本発明の油圧駆動装置は、互いに抗する方向に２つのパイロット圧が入力され、前記２つのパイロット圧の差圧に応じて所定方向一方及び他方に夫々移動してメインポンプから油圧アクチュエータに流れる作動油の方向を切換えると共に前記メインポンプと油圧アクチュエータとの間の開度を制御するスプールを有する流量制御弁と、一定の設定圧に保たれた圧油を供給する圧源から供給される圧油を一次圧とする正比例型の電磁比例制御弁であって、入力される電流に応じた第１出力圧に減圧制御し、前記第１出力圧を前記２つのパイロット圧のうちの一方である第１パイロット圧として前記流量制御弁に出力して前記スプールを前記所定方向一方に移動させる正比例型の第１電磁比例制御弁と、前記圧力源から供給される圧油を一次圧とする正比例型の電磁比例制御弁であって、入力される電流に応じた第２出力圧に減圧制御して出力する正比例型の第２電磁比例制御弁と、前記圧力源から供給される設定圧及び前記第２電磁比例制御弁から出力される前記第２出力圧のうち何れかを前記２つのパイロット圧のうちの他方である第２パイロット圧として前記流量制御弁に出力して前記スプールを前記所定方向他方に移動させる切換弁と、前記第１電磁比例制御弁と前記流量制御弁との間の通路から分岐して前記切換弁に接続する油通路と、互いに異なる第１方向及び第２方向に操作可能な操作装置と、前記第１電磁比例制御弁及び前記第２電磁比例制御弁が正常に作動する状態で、且つ前記操作装置が前記第１方向に操作される場合は、その第１方向操作量に応じた電流を前記第１電磁比例制御弁に流し、前記操作装置が前記第２方向に操作される場合は、その第２方向操作量に応じた電流を前記第２電磁比例制御弁に流す制御ユニットと、を備え、前記切換弁には前記第１パイロット圧と前記第２出力圧とが互いに抗するように入力され、前記切換弁は、前記第１パイロット圧から前記第２出力圧を差し引いた差分が予め定められた所定圧力以上である場合は、前記設定圧を第２パイロット圧として前記流量制御弁に出力し、前記差分が前記所定圧力未満である場合は、前記第２出力圧を前記第２パイロット圧として出力し、前記制御ユニットは、前記操作装置が前記第２方向に操作されても前記第２出力圧がゼロに維持されるような故障が前記第２電磁比例制御弁又はその配線経路に生じていると判断した場合は、前記第１電磁比例制御弁に通電して前記所定圧力以上で且つ前記操作装置の第２方向操作量に応じた前記第１出力圧を前記第１パイロット圧として前記第１電磁比例制御弁から前記流量制御弁及び前記切換弁に出力させるものである。 In the hydraulic drive system according to the present invention, two pilot pressures are input in the opposite direction to each other, and movement according to the pressure difference between the two pilot pressures is performed in one and the other in the predetermined directions and flows from the main pump to the hydraulic actuator A flow control valve having a spool that switches the direction of oil and controls the opening between the main pump and the hydraulic actuator, and pressure oil supplied from a pressure source that supplies pressure oil maintained at a constant set pressure A proportional proportional type electromagnetic proportional control valve, wherein the first output pressure is controlled to be one of the two pilot pressures. (1) A direct proportional type first electromagnetic proportional control valve that outputs to the flow control valve as one pilot pressure to move the spool in one of the predetermined directions, and pressure oil supplied from the pressure source is used as a primary pressure And a proportional proportional second electromagnetic proportional control valve for performing pressure reduction control to a second output pressure according to the input current, and a set pressure supplied from the pressure source And any one of the second output pressure outputted from the second electromagnetic proportional control valve as the second pilot pressure, which is the other of the two pilot pressures, to the flow control valve to cause the spool to A switching valve for moving the other in the predetermined direction, an oil passage branched from a passage between the first electromagnetic proportional control valve and the flow control valve and connected to the switching valve, and a first direction and a second direction different from each other The first electromagnetic proportional control valve and the second electromagnetic proportional control valve operate normally, and the first electromagnetic directional control valve operates in the first direction. Forward current according to the amount of directional operation A control unit for causing a current to flow to the second electromagnetic proportional control valve, which flows to the first electromagnetic proportional control valve, and when the operating device is operated in the second direction, supplies a current corresponding to the second directional operation amount to the second electromagnetic proportional control valve; The first pilot pressure and the second output pressure are input to the switching valve so as to be opposed to each other, and the switching valve has a predetermined difference obtained by subtracting the second output pressure from the first pilot pressure. When the pressure is equal to or higher than the predetermined pressure, the set pressure is output as the second pilot pressure to the flow control valve, and when the difference is less than the predetermined pressure, the second output pressure is the second pilot pressure. And the control unit generates a fault in the second electromagnetic proportional control valve or its wiring path such that the second output pressure is maintained at zero even if the operating device is operated in the second direction. If it is determined that The first output pressure corresponding to the second direction operation amount of the operating device at the predetermined pressure or more by supplying power to the first electromagnetic proportional control valve from the first electromagnetic proportional control valve as the first pilot pressure It makes it output to the said flow control valve and the said switching valve.
　本発明に従えば、第２電磁比例制御弁又はその配線経路に故障がない状態において、操作装置が第２方向に操作されると、操作装置の操作量に応じた第２出力圧が出力される。他方、第１電磁比例制御弁からの出力がなければ、第１パイロット圧から第２出力圧を引いた差分が所定圧力以下となり、第２出力圧が第２パイロット圧として切換弁から流量制御弁に出力される。これにより、流量制御弁のスプールは、所定方向他方に且つ第２出力圧に応じた位置へと移動し、メインポンプと油圧アクチュエータとの間の開度が第２出力圧に応じた開度となる。即ち、操作装置の操作量に応じた流量の作動油を油圧アクチュエータに流すことができ、操作装置の操作量に応じた速度で油圧アクチュエータを動かすことができる。 According to the present invention, when the operating device is operated in the second direction with no failure in the second electromagnetic proportional control valve or its wiring path, the second output pressure corresponding to the amount of operation of the operating device is output. Ru. On the other hand, if there is no output from the first solenoid proportional control valve, the difference between the first pilot pressure and the second output pressure becomes equal to or less than the predetermined pressure, and the second output pressure becomes the second pilot pressure from the switching valve to the flow control valve Output to Thus, the spool of the flow control valve moves in the other direction to the position corresponding to the second output pressure, and the opening degree between the main pump and the hydraulic actuator corresponds to the second output pressure. Become. That is, the hydraulic fluid of the flow rate according to the operation amount of the operating device can be flowed to the hydraulic actuator, and the hydraulic actuator can be moved at a speed according to the operation amount of the operating device.
　他方、例えば第２電磁比例制御弁の配線経路に故障が生じている状態において、操作装置が第２方向に操作されると、制御ユニットは、第２電磁比例制御弁ではなく第１電磁比例制御弁に通電して、第１電磁比例制御弁から所定圧力以上の第１出力圧を出力させる。これにより、第１パイロット圧が所定圧力以上になり、設定圧が第２パイロット圧として切換弁から流量制御弁に出力される。即ち、互いに抗する２つパイロット圧がスプールに作用するようになる。ここで、第１パイロット圧は、設定圧以下に制御され、第２パイロット圧は設定圧と同圧になっている。それ故、２つのパイロット圧がスプールに作用することによってスプールが所定方向他方に且つその差分に応じた位置に移動する。従って、操作装置の操作量に応じて第１出力圧を調整することによって２つのパイロット圧の差分を調整することができ、第２電磁比例制御弁の配線経路において故障が生じてもスプールを操作装置の第２方向操作量に応じた位置に移動させることができる。即ち、電磁比例制御弁の配線経路において故障が生じた場合のように、第２電磁比例制御弁からの出力圧がゼロのままに維持されるような故障が第２電磁比例制御弁に生じた場合において、操作装置の第２方向操作量に応じた流量の作動油を油圧アクチュエータに流すことができ、操作装置の第２方向操作量に応じた速度で油圧アクチュエータを動かすことができる。 On the other hand, for example, in a state where a fault occurs in the wiring path of the second electromagnetic proportional control valve, when the operating device is operated in the second direction, the control unit does not perform the second electromagnetic proportional control valve but the first electromagnetic proportional control The valve is energized to cause the first electromagnetic proportional control valve to output a first output pressure equal to or higher than a predetermined pressure. As a result, the first pilot pressure becomes equal to or higher than the predetermined pressure, and the set pressure is output from the switching valve to the flow control valve as the second pilot pressure. That is, two pilot pressures opposing each other act on the spool. Here, the first pilot pressure is controlled to be equal to or lower than the set pressure, and the second pilot pressure is equal to the set pressure. Therefore, the two pilot pressures act on the spool to move the spool in the other direction and to a position according to the difference. Therefore, the difference between the two pilot pressures can be adjusted by adjusting the first output pressure according to the amount of operation of the operating device, and the spool is operated even if a failure occurs in the wiring path of the second electromagnetic proportional control valve. It can be moved to the position according to the second direction operation amount of the device. That is, as in the case where a fault occurs in the wiring path of the electromagnetic proportional control valve, the second electromagnetic proportional control valve has a fault in which the output pressure from the second electromagnetic proportional control valve is maintained at zero. In this case, hydraulic oil at a flow rate corresponding to the second direction operation amount of the operating device can be flowed to the hydraulic actuator, and the hydraulic actuator can be moved at a speed according to the second direction operation amount of the operating device.
　なお、操作装置が第１方向に操作される場合には、第２電磁比例制御弁又はその配線経路における故障の有無に関わらず、制御ユニットが操作装置の操作量に応じた電流を第１電磁比例制御弁に出力する。そうすると、操作装置の操作量に応じた圧力の第１出力圧が第１パイロット圧として第１電磁比例制御弁から流量制御弁に出力され、操作装置が操作される第１方向であって且つその操作量に応じた位置にスプールが移動する。これにより、操作装置の第１方向操作量に応じた流量の作動油を油圧アクチュエータに流すことができ、操作装置の第１方向操作量に応じた速度で油圧アクチュエータを動かすことができる。 When the operating device is operated in the first direction, the control unit generates a current corresponding to the amount of operation of the operating device, regardless of the presence or absence of a failure in the second electromagnetic proportional control valve or its wiring path. Output to proportional control valve. Then, the first output pressure of the pressure according to the operation amount of the operating device is output as the first pilot pressure from the first electromagnetic proportional control valve to the flow control valve, and in the first direction in which the operating device is operated The spool moves to a position according to the amount of operation. As a result, hydraulic oil at a flow rate corresponding to the first direction operation amount of the operating device can be flowed to the hydraulic actuator, and the hydraulic actuator can be moved at a speed according to the first direction operation amount of the operating device.
　上記発明において、前記スプールは、前記第２パイロット圧に比べて前記第１パイロット圧が大きく且つ前記２つのパイロット圧の差圧が予め定められる規定圧力に達すると、前記所定方向一方へスプールのストローク量が最大となるように構成され、前記切換弁は、前記所定圧力が前記規定圧力より大きくなるように構成されていてもよい。 In the above invention, when the spool has the first pilot pressure greater than the second pilot pressure and the differential pressure between the two pilot pressures reaches a predetermined pressure, the stroke of the spool in one of the predetermined directions is made. The amount may be configured to be maximum, and the switching valve may be configured such that the predetermined pressure is higher than the specified pressure.
　上記構成に従えば、規定圧力が所定圧力よりも低く設定されているので、第２電磁比例制御弁又はその配線経路が故障している状態において、第１パイロット圧を規定圧力まで昇圧しても設定圧が第２パイロット圧として出力されることがない。それ故、第２電磁比例制御弁又はその配線経路が故障している状態においても、スプールを所定方向一方に向かって最大ストローク量までストロークさせることができる。即ち、第２電磁比例制御弁又はその配線経路が故障している状態において、第１パイロット圧によってスプールを所定方向一方に移動させる際に油圧駆動装置の機能が低下することを抑えることができる。 According to the above configuration, the prescribed pressure is set lower than the prescribed pressure, so even if the second electromagnetic proportional control valve or its wiring path is broken, even if the first pilot pressure is boosted to the prescribed pressure. The set pressure is not output as the second pilot pressure. Therefore, even in a state where the second electromagnetic proportional control valve or its wiring path is broken, the spool can be made to travel in one direction in the predetermined direction to the maximum stroke amount. That is, in the state where the second electromagnetic proportional control valve or the wiring path thereof is broken, it is possible to suppress the deterioration of the function of the hydraulic drive when moving the spool in one direction by the first pilot pressure.
　上記発明において、前記第１電磁比例制御弁から出力される前記第１出力圧及び前記圧力源によって一定に保たれている設定圧のうち何れか一方を前記第１パイロット圧として前記流量制御弁に出力する第１切換弁、を更に備え、前記第１切換弁には前記第２パイロット圧と前記第１出力圧とが互いに抗するように入力され、前記第１切換弁は、前記第２パイロット圧から前記第１出力圧を差し引いた第１差分が第１所定圧力以上である場合は、前記設定圧を前記第１パイロット圧として出力し、前記第１差分が前記第１所定圧力未満である場合は、前記第１出力圧を前記第１パイロット圧として出力し、前記切換弁である第２切換弁には前記第１パイロット圧と前記第２出力圧とが互いに抗するように入力され、前記第２切換弁は、前記第１パイロット圧から前記第２出力圧を差し引いた差分である第２差分が所定圧力である第２所定圧力以上である場合は、前記設定圧を前記第２パイロット圧として前記流量制御弁に出力し、前記第２差分が前記第２所定圧力未満である場合は、前記第２出力圧を前記第２パイロット圧として前記流量制御弁に出力し、前記制御ユニットは、前記操作装置が前記第１方向に操作されても前記第１出力圧がゼロに維持されるような故障が前記第１電磁比例制御弁又はその配線経路に生じていると判断した場合は、前記第２電磁比例制御弁に通電して前記第１所定圧力以上で且つ前記操作装置の第１方向操作量に応じた前記第２出力圧を前記第２パイロット圧として前記第２電磁比例制御弁から前記流量制御弁及び前記第２切換弁に出力させてもよい。 In the above invention, either one of the first output pressure output from the first electromagnetic proportional control valve and the set pressure maintained constant by the pressure source is used as the first pilot pressure in the flow rate control valve. The first switching valve is further provided, and the second switching pressure is input to the first switching valve so that the second pilot pressure and the first output pressure oppose each other, and the first switching valve is the second pilot. If the first difference obtained by subtracting the first output pressure from the pressure is equal to or higher than the first predetermined pressure, the set pressure is output as the first pilot pressure, and the first difference is less than the first predetermined pressure In this case, the first output pressure is output as the first pilot pressure, and the first pilot pressure and the second output pressure are input to the second switching valve, which is the switching valve, so as to oppose each other, The second switching valve is If the second difference which is the difference obtained by subtracting the second output pressure from the one pilot pressure is equal to or greater than a second predetermined pressure which is a predetermined pressure, the set pressure is output to the flow control valve as the second pilot pressure If the second difference is less than the second predetermined pressure, the second output pressure is output as the second pilot pressure to the flow control valve, and the control unit causes the controller to operate in the first direction. If it is determined that the first electromagnetic proportional control valve or its wiring path has a failure such that the first output pressure is maintained at zero even if operated, the second electromagnetic proportional control valve is energized. The second output pressure corresponding to the first predetermined pressure or more and corresponding to the first direction operation amount of the operating device is the second pilot pressure, and the second electromagnetic proportional control valve controls the flow control valve and the second control pressure. Even when switching valve output There.
　上記構成に従えば、第１電磁比例制御弁又はその配線経路が故障している状態においても、操作装置に対する第１方向及び第２方向の操作の何れであっても操作装置の操作量に応じた流量の作動油を油圧アクチュエータに流すことができ、操作装置の操作量に応じた速度で油圧アクチュエータを動かすことができる。 According to the above configuration, even when the first electromagnetic proportional control valve or the wiring path thereof is broken, the operation amount of the operation device is used regardless of whether the operation in the first direction or the second direction is performed on the operation device. It is possible to flow the hydraulic fluid at a different flow rate to the hydraulic actuator, and move the hydraulic actuator at a speed according to the operation amount of the operating device.
　上記発明において、前記スプールは、前記第２パイロット圧に比べて前記第１パイロット圧が大きく且つ前記２つのパイロット圧の差圧が予め定められた第１規定圧力に達すると前記所定方向一方へのストローク量が最大となり、前記第１パイロット圧に比べて前記第２パイロット圧が大きく且つ前記２つのパイロット圧の差圧が予め定められる第２規定圧力に達すると、前記所定方向他方へのストローク量が最大となるように構成され、前記第１切換弁は、前記第１所定圧力が前記第１規定圧力より大きくなるように構成され、前記第２切換弁は、前記第２所定圧力が前記第２規定圧力より大きくなるように構成されていてもよい。 In the above invention, the spool has the first pilot pressure greater than the second pilot pressure, and the differential pressure between the two pilot pressures reaches a predetermined first prescribed pressure in one of the predetermined directions. When the stroke amount is maximum, the second pilot pressure is larger than the first pilot pressure, and the differential pressure between the two pilot pressures reaches a second predetermined pressure defined in advance, the stroke amount in the other direction in the predetermined direction Is configured to be maximum, the first switching valve is configured such that the first predetermined pressure is higher than the first prescribed pressure, and the second switching valve is configured to have the second predetermined pressure be the second predetermined pressure. It may be configured to be greater than 2 specified pressure.
　上記構成に従えば、第１規定圧力が第１所定圧力よりも低く設定されているので、第１電磁比例制御弁が通電不可な状態において、第２パイロット圧を規定圧力まで昇圧しても設定圧が第１パイロット圧として出力されることがない。それ故、第１電磁比例制御弁又はその配線経路が故障している状態においても、スプールを所定方向他方に向かって最大ストローク量までストロークさせることができる。即ち、第１電磁比例制御弁又はその配線経路が故障している状態において、スプールを所定方向他方に移動させる際に油圧駆動システムの機能が低下することを抑えることができる。 According to the above configuration, since the first prescribed pressure is set lower than the first prescribed pressure, setting is made even if the second pilot pressure is boosted to the prescribed pressure in a state in which the first electromagnetic proportional control valve can not be energized. Pressure is not output as the first pilot pressure. Therefore, even in a state where the first electromagnetic proportional control valve or its wiring path is broken, the spool can be made to stroke in the other direction to the maximum stroke amount. That is, in the state where the first electromagnetic proportional control valve or its wiring path is broken, it is possible to suppress the deterioration of the function of the hydraulic drive system when moving the spool to the other side in the predetermined direction.
　また、同様に、第２規定圧力が第２所定圧力よりも低く設定されているので、第２電磁比例制御弁又はその配線経路が故障している状態においてもまた、スプールを所定方向他方に向かって最大ストローク量までストロークさせることができる。即ち、スプールを所定方向一方に移動させる際に油圧駆動システムの機能が低下することを抑えることができる。 Similarly, since the second prescribed pressure is set lower than the second prescribed pressure, the spool is directed in the other direction in the other direction also in the state where the second electromagnetic proportional control valve or its wiring path is broken. Stroke to the maximum stroke amount. That is, when the spool is moved in one direction, it is possible to suppress the deterioration of the function of the hydraulic drive system.
　上記発明において、前記スプールは、前記２つのパイロット圧の差圧がゼロの場合において、前記メインポンプと前記油圧アクチュエータとの間を遮断する中立位置に位置してもよい。 In the above invention, the spool may be located at a neutral position for interrupting between the main pump and the hydraulic actuator when the differential pressure between the two pilot pressures is zero.
　上記構成に従えば、第２電磁比例制御弁が、二次圧ポートが一次圧ポートと連通する状態でスティックして制御不能になった場合、第２電磁比例制御弁から設定圧と同圧の第２出力圧が出力されることになる。そうすると、第２パイロット圧として設定圧と同圧の第２出力圧が第２切換弁から流量制御弁に出力される。他方、第１切換弁においては設定圧と同圧の第２出力圧が第２パイロット圧として入力されることにより、第１切換弁は第１パイロット圧として設定圧を前記流量制御弁に出力するようになる。これにより、流量制御弁のスプールに同圧の第１パイロット圧及び第２パイロット圧が互いに抗するように作用し、スプールが中立位置に保持される。その結果、作動油が油圧アクチュエータに導かれて不所望な動きをすることを防ぐことができ、フェールセーフを達成することができる。 According to the above configuration, when the second electromagnetic proportional control valve sticks out in a state where the secondary pressure port is in communication with the primary pressure port and becomes uncontrollable, the second electromagnetic proportional control valve has the same pressure as the set pressure. The second output pressure is to be output. Then, a second output pressure equal to the set pressure as the second pilot pressure is output from the second switching valve to the flow rate control valve. On the other hand, in the first switching valve, the second output pressure equal to the set pressure is input as the second pilot pressure, whereby the first switch valve outputs the set pressure as the first pilot pressure to the flow rate control valve It will be. Thereby, the first pilot pressure and the second pilot pressure of the same pressure act on the spool of the flow control valve so as to oppose each other, and the spool is held at the neutral position. As a result, hydraulic fluid can be prevented from being guided to the hydraulic actuator to perform an undesired movement, and fail safe can be achieved.
　本発明の油圧駆動システムは、前述する油圧駆動装置と、前記油圧アクチュエータに供給する作動油を吐出するメインポンプと、前記圧力源を構成するサブポンプとを備えるものである。 A hydraulic drive system according to the present invention includes the above-described hydraulic drive device, a main pump that discharges hydraulic oil supplied to the hydraulic actuator, and a sub pump that constitutes the pressure source.
　上記構成に従えば、前述するような機能を有する油圧駆動システムを実現することができる。 According to the above configuration, a hydraulic drive system having the functions as described above can be realized.
　本発明によれば、電磁比例制御弁からの出力圧がゼロのままに維持されるような故障が生じても、操作装置の操作に応じて油圧アクチュエータを動作させることができる。 According to the present invention, the hydraulic actuator can be operated according to the operation of the operating device even if a failure occurs such that the output pressure from the electromagnetic proportional control valve is maintained at zero.
本実施形態の油圧駆動システムの構成を示す回路図である。It is a circuit diagram showing composition of a hydraulic drive system of this embodiment. 図１の油圧駆動システムに備わる流量制御弁のスプールに作用するパイロット圧とスプールのストローク量との関係を示すグラフである。It is a graph which shows the relationship between the pilot pressure which acts on the spool of the flow control valve with which the hydraulic drive system of FIG. 1 is equipped, and the stroke amount of a spool. 図１の油圧駆動システムに備わる第２電磁比例制御弁が故障した際に第１電磁比例制御弁から出力させる圧力とスプールに作用するパイロット圧との関係を示すグラフである。It is a graph which shows the relationship between the pressure output from a 1st electromagnetic proportional control valve, and the pilot pressure which acts on a spool, when the 2nd electromagnetic proportional control valve with which the hydraulic drive system of FIG. 1 is equipped fails.
　以下、本発明に係る実施形態の油圧駆動システム１について図面を参照して説明する。なお、以下の説明で用いる方向の概念は、説明する上で便宜上使用するものであって、発明の構成の向き等をその方向に限定するものではない。また、以下に説明する油圧駆動システム１は、本発明の一実施形態に過ぎない。従って、本発明は実施形態に限定されず、発明の趣旨を逸脱しない範囲で追加、削除、変更が可能である。 Hereinafter, a hydraulic drive system 1 according to an embodiment of the present invention will be described with reference to the drawings. The concept of the direction used in the following description is used for convenience of the description, and the direction of the configuration of the invention is not limited to that direction. Moreover, the hydraulic drive system 1 described below is only one embodiment of the present invention. Accordingly, the present invention is not limited to the embodiments, and additions, deletions, and modifications are possible without departing from the scope of the invention.
　建設機械では、様々なアタッチメントを備えており、それらが油圧シリンダや油圧モータ等の油圧アクチュエータ２によって動かされている。また、建設機械では、油圧アクチュエータ２を動かすべく油圧駆動システム１を備えている。油圧駆動システム１は、作動油を油圧アクチュエータ２（本実施形態において油圧シリンダ）に供給して油圧アクチュエータ２を駆動するようになっている。なお、本実施形態では、説明の便宜上、油圧駆動システム１に１つの油圧アクチュエータ２だけが接続されているが、油圧駆動システム１に２つ以上の油圧アクチュエーが接続されてもよい。以下では、油圧駆動システム１の構成について更に詳細に説明する。 In a construction machine, various attachments are provided, which are moved by a hydraulic actuator 2 such as a hydraulic cylinder or a hydraulic motor. In addition, in the construction machine, the hydraulic drive system 1 is provided to move the hydraulic actuator 2. The hydraulic drive system 1 supplies hydraulic fluid to a hydraulic actuator 2 (a hydraulic cylinder in the present embodiment) to drive the hydraulic actuator 2. In the present embodiment, for convenience of explanation, only one hydraulic actuator 2 is connected to the hydraulic drive system 1, but two or more hydraulic actuators may be connected to the hydraulic drive system 1. Hereinafter, the configuration of the hydraulic drive system 1 will be described in more detail.
　［油圧駆動システム］
　油圧駆動システム１は、メインポンプ１１と、タンク１２と、エンジンＥと、サブポンプ１３と、油圧駆動装置１４とを備えている。メインポンプ１１は、可変容量型の斜板ポンプであって、吸入ポート１１ａにタンク１２が接続され、吐出ポート１１ｂに油圧駆動装置１４が接続されている。また、メインポンプ１１は、エンジンＥに接続されており、エンジンＥは、メインポンプ１１の回転軸１１ｃを予め定められた任意の回転数にて回転させるようになっている。また、メインポンプ１１は、傾転角を変更可能な斜板１１ｄを有しており、斜板１１ｄの傾転角を変えることによってメインポンプ１１の吐出容量を調整できるようになっている。更に、メインポンプ１１の斜板１１ｄにはレギュレータ１５が設けられており、レギュレータ１５によって斜板１１ｄの傾転角を変更できるようになっている。 [Hydraulic drive system]
The hydraulic drive system 1 includes a main pump 11, a tank 12, an engine E, a sub pump 13, and a hydraulic drive device 14. The main pump 11 is a variable displacement swash plate pump, the tank 12 is connected to the suction port 11a, and the hydraulic drive 14 is connected to the discharge port 11b. Further, the main pump 11 is connected to the engine E, and the engine E is configured to rotate the rotation shaft 11 c of the main pump 11 at an arbitrary predetermined rotational speed. Further, the main pump 11 has a swash plate 11 d capable of changing the tilt angle, and the discharge displacement of the main pump 11 can be adjusted by changing the tilt angle of the swash plate 11 d. Further, a regulator 15 is provided on the swash plate 11 d of the main pump 11 so that the tilt angle of the swash plate 11 d can be changed by the regulator 15.
　このように構成されているメインポンプ１１は、エンジンＥが回転軸１１ｃを回転させることによって作動油を吐出するようになっており、吐出される作動油の流量（即ち、吐出流量）は、斜板１１ｄの傾転角とエンジンＥの回転数に応じた流量となっている。このような機能を有するメインポンプ１１の回転軸１１ｃには、更にサブポンプ１３の回転軸１３ａが回転軸１１ｃと一体的に回転するようになっている。なお、本実施形態において、サブポンプ１３は、メインポンプ１１と直列的に接続されているが、並列的に接続されてもよく、またエンジンＥに対してメインポンプ１１とは反対側に接続されてもよい。 The main pump 11 configured as described above discharges the hydraulic fluid by rotating the rotation shaft 11c of the engine E, and the flow rate of the hydraulic fluid to be discharged (ie, the discharge flow rate) is oblique. The flow rate corresponds to the tilt angle of the plate 11 d and the rotational speed of the engine E. The rotating shaft 13a of the sub pump 13 is further rotated integrally with the rotating shaft 11c on the rotating shaft 11c of the main pump 11 having such a function. In the present embodiment, the sub pump 13 is connected in series to the main pump 11. However, the sub pump 13 may be connected in parallel, and may be connected on the opposite side of the engine E to the main pump 11. It is also good.
　このように接続されているサブポンプ１３は、固定容量型のポンプであり、吸入ポート１３ｂにタンク１２が接続され、吐出ポート１３ｃに油圧駆動装置１４のサブ通路２０が接続されている。また、サブポンプ１３の回転軸１３ａは、回転軸１１ｃを介してエンジンＥに繋がっており、エンジンＥの回転数に応じた回転数で回転するようになっている。更に、サブポンプ１３は、回転することによってサブ通路２０に圧油を吐出するようになっており、サブ通路２０には、この圧油の圧力を一定に保つべくリリーフ弁２８が設けられている。 The sub pump 13 connected in this manner is a fixed displacement type pump, the tank 12 is connected to the suction port 13 b, and the sub passage 20 of the hydraulic drive device 14 is connected to the discharge port 13 c. The rotation shaft 13a of the sub pump 13 is connected to the engine E via the rotation shaft 11c, and rotates at a rotational speed corresponding to the rotational speed of the engine E. Furthermore, the sub pump 13 discharges pressure oil to the sub passage 20 by rotating, and the sub passage 20 is provided with a relief valve 28 to keep the pressure of the pressure oil constant.
　リリーフ弁２８は、サブ通路２０とタンク１２を連通するように配置されている。リリーフ弁２８は、サブ通路２０の油圧が予め定められる設定圧を超えるとサブ通路２０を流れる作動油を排出し、サブポンプ１３のサブポンプ吐出圧ｐｐを設定圧（即ち、一定圧）にて維持する。このようにして油圧駆動装置１４には、一定圧の圧油が供給されている。 The relief valve 28 is disposed to communicate the sub passage 20 with the tank 12. The relief valve 28 discharges the hydraulic fluid flowing through the sub passage 20 when the hydraulic pressure of the sub passage 20 exceeds a predetermined set pressure, and maintains the sub pump discharge pressure pp of the sub pump 13 at the set pressure (that is, constant pressure). . Thus, the hydraulic drive unit 14 is supplied with pressure oil at a constant pressure.
　［油圧駆動装置］
　油圧駆動装置１４は、サブポンプ１３からのサブポンプ吐出圧ｐｐを利用して作動し、またメインポンプ１１から吐出された作動油を油圧アクチュエータ２のどちらの通路へ導くかを切換えたり流量を調整したりすることによって油圧アクチュエータ２の動きを制御するようになっている。更に詳細に説明すると、油圧駆動装置１４は、流量制御弁２１と、第１電磁比例制御弁２２Ｒと、第２電磁比例制御弁２２Ｌと、第１切換弁２４Ｒと、第２切換弁２４Ｌと、制御ユニット２６と、操作装置２７とを備えている。 [Hydraulic drive]
The hydraulic drive unit 14 operates using the sub pump discharge pressure pp from the sub pump 13 and switches to which path of the hydraulic actuator 2 the hydraulic oil discharged from the main pump 11 is to be led or adjusts the flow rate By doing this, the movement of the hydraulic actuator 2 is controlled. More specifically, the hydraulic drive device 14 includes a flow control valve 21, a first electromagnetic proportional control valve 22R, a second electromagnetic proportional control valve 22L, a first switching valve 24R, and a second switching valve 24L. A control unit 26 and an operating device 27 are provided.
　流量制御弁２１は、メインポンプ１１と油圧アクチュエータ２とに接続されており、メインポンプ１１から油圧アクチュエータ２に流れる作動油の方向及び流量を制御するようになっている。更に詳細に説明すると、油圧アクチュエータ２は、２つのポート２ａ，２ｂを有しており、流量制御弁２１は、２つのポート２ａ，２ｂに接続されている。また、流量制御弁２１は、メインポンプ１１の吐出ポート１１ｂ及びタンク１２に接続され、これらの接続状態を切換えるべくスプール２１ａを有している。即ち、流量制御弁２１は、スプール２１ａを動かすことによって作動油の流れる方向及び流量制御弁２１の開度を調整できるようになっている。 The flow control valve 21 is connected to the main pump 11 and the hydraulic actuator 2 so as to control the direction and flow rate of hydraulic fluid flowing from the main pump 11 to the hydraulic actuator 2. More specifically, the hydraulic actuator 2 has two ports 2a and 2b, and the flow control valve 21 is connected to the two ports 2a and 2b. Further, the flow control valve 21 is connected to the discharge port 11b of the main pump 11 and the tank 12, and has a spool 21a to switch the connection state of these. That is, the flow control valve 21 can adjust the flow direction of the hydraulic fluid and the opening degree of the flow control valve 21 by moving the spool 21 a.
　更に詳細に説明すると、スプール２１ａは、所定方向一方及び他方、即ち中立位置Ｍ０から第１オフセット位置Ｍ１及び第２オフセット位置Ｍ２に夫々移動できるようになっており、中立位置Ｍ０において、メインポンプ１１と油圧アクチュエータ２との間、及び油圧アクチュエータ２とタンク１２との間を夫々遮断して作動油がそれらの間を流れないようになっている。スプール２１ａが第１オフセット位置Ｍ１に位置すると、メインポンプ１１の吐出ポート１１ｂと油圧アクチュエータ２の第１ポート（本実施形態において、ヘッド側ポート）２ａとが接続され、油圧アクチュエータ２の第２ポート（本実施形態において、ロッド側ポート）２ｂとタンク１２とが接続される。この際、吐出ポート１１ｂと第１ポート２ａとの間はスプール２１ａの位置に応じた開度で繋がり、スプール２１ａの位置（ストローク量）に応じた流量の作動油が第１ポート２ａに導かれる。これにより、スプール２１ａの位置に応じた速度で油圧アクチュエータ２が伸長する。他方、スプール２１ａが第２オフセット位置Ｍ２に位置すると、メインポンプ１１の吐出ポート１１ｂと油圧アクチュエータ２の第２ポート２ｂとが接続され、また油圧アクチュエータ２の第１ポート２ａとタンク１２とが接続される。この際、吐出ポート１１ｂと第２ポート２ｂとの間はスプール２１ａの位置に応じた開度で繋がり、スプール２１ａの位置に応じた流量の作動油が第２ポート２ｂに導かれる。これにより、スプール２１ａの位置に応じた速度で油圧アクチュエータ２が収縮する。 More specifically, the spool 21a can be moved from one direction and the other in a predetermined direction, ie, from the neutral position M0 to the first offset position M1 and the second offset position M2, respectively. Between the hydraulic actuator 2 and the hydraulic actuator 2 and between the hydraulic actuator 2 and the tank 12 so that hydraulic fluid does not flow between them. When the spool 21 a is located at the first offset position M 1, the discharge port 11 b of the main pump 11 and the first port (in the present embodiment, the head side port) 2 a of the hydraulic actuator 2 are connected, and the second port of the hydraulic actuator 2 (In the present embodiment, the rod side port) 2b and the tank 12 are connected. At this time, the discharge port 11b and the first port 2a are connected at an opening degree according to the position of the spool 21a, and hydraulic oil of a flow rate according to the position (stroke amount) of the spool 21a is guided to the first port 2a . Thus, the hydraulic actuator 2 extends at a speed corresponding to the position of the spool 21a. On the other hand, when the spool 21a is located at the second offset position M2, the discharge port 11b of the main pump 11 and the second port 2b of the hydraulic actuator 2 are connected, and the first port 2a of the hydraulic actuator 2 and the tank 12 are connected Be done. At this time, the discharge port 11b and the second port 2b are connected at an opening degree corresponding to the position of the spool 21a, and hydraulic oil having a flow rate corresponding to the position of the spool 21a is guided to the second port 2b. As a result, the hydraulic actuator 2 contracts at a speed corresponding to the position of the spool 21a.
　このように構成される流量制御弁２１は、２つのばね３１Ｌ，３１Ｒを更に有しており、２つのばね３１Ｌ，３１Ｒは、互いに抗するようにスプール２１ａを付勢してスプール２１ａを中立位置Ｍ０に維持している。また、流量制御弁２１は、２つのパイロットポート２１Ｒ，２１Ｌを有しており、各々にパイロット圧ｐｉＲ，ｐｉＬが入力されるようになっている。第１パイロットポート２１Ｒは、そこに入力される第１パイロット圧ｐｉＲが第１のばね３１Ｌに抗するようにスプール２１ａに作用するように形成されており、スプール２１ａは、第１パイロット圧ｐｉＲによって第１オフセット位置Ｍ１の方に押圧されるようになっている。また、第２パイロットポート２１Ｌは、そこに入力される第２パイロット圧ｐｉＬが第２のばね３１Ｒに抗するようにスプール２１ａに作用するように形成されており、スプール２１ａは、第２パイロット圧ｐｉＬによって第２オフセット位置Ｍ２の方に押圧されるようになっている。それ故、スプール２１ａは、そこに作用する２つのパイロット圧ｐｉＲ，ｐｉＬの差圧に応じた位置へと移動し、その位置に応じた方向かつ流量の作動油を油圧アクチュエータ２に流すようになっている。このように入力される２つのパイロット圧ｐｉＲ，ｐｉＬは、サブポンプ１３から吐出されるサブポンプ吐出圧ｐｐから生成されており、２つのパイロット圧ｐｉＲ，ｐｉＬを生成すべくサブポンプ１３にはサブ通路２０を介して２つの電磁比例制御弁２２Ｒ，２２Ｌが並列に接続されている。 The flow control valve 21 configured in this manner further includes two springs 31L and 31R, and the two springs 31L and 31R bias the spool 21a so as to oppose each other so that the spool 21a is in the neutral position. It is maintained at M0. In addition, the flow control valve 21 has two pilot ports 21R and 21L, and the pilot pressures piR and piL are respectively input to the flow control valve 21. The first pilot port 21R is formed to act on the spool 21a so that the first pilot pressure piR inputted thereto opposes the first spring 31L, and the spool 21a is operated by the first pilot pressure piR. It is pressed toward the first offset position M1. In addition, the second pilot port 21L is formed to act on the spool 21a so that the second pilot pressure piL input thereto opposes the second spring 31R, and the spool 21a is a second pilot pressure. It is pushed toward the second offset position M2 by piL. Therefore, the spool 21a moves to a position corresponding to the differential pressure between the two pilot pressures piR and piL acting thereon, and hydraulic fluid in a direction and flow rate corresponding to the position flows to the hydraulic actuator 2 ing. The two pilot pressures piR and piL thus input are generated from the sub pump discharge pressure pp discharged from the sub pump 13, and the sub pump 20 is connected to the sub pump 13 to generate two pilot pressures piR and piL. The two electromagnetic proportional control valves 22R and 22L are connected in parallel via each other.
　２つの電磁比例制御弁２２Ｒ，２２Ｌのうちの一方である第１電磁比例制御弁２２Ｒでは、一次圧ポートがサブポンプ１３及びタンク１２の何れかに選択的に接続され、二次圧ポートが第１切換弁２４Ｒに接続されている。また、第１電磁比例制御弁２２Ｒには、そのソレノイド部２２Ｒａに電流を流す（即ち、第１指令信号を入力する）ことができるようになっており、ソレノイド部２２Ｒａに流す電流に応じて開度を切換えるようになっている。即ち、第１電磁比例制御弁２２Ｒは、正比例型の電磁比例制御弁であり、ソレノイド部２２Ｒａに電流を流すことによってサブポンプ１３と二次圧ポートとが接続され、サブポンプ１３と二次圧ポートとの間がソレノイド部２２Ｒａに流れる電流に応じた開度で開かれる。他方、ソレノイド部２２Ｒａに流れる電流が止められると、サブポンプ１３と弁二次圧ポートとの間が遮断されて弁二次圧ポートがタンク１２と接続される。このように構成されている第１電磁比例制御弁２２Ｒは、サブポンプ吐出圧ｐｐをソレノイド部２２Ｒａに流される電流に応じた圧力（第１出力圧ｐｓＲ）に減圧制御して二次圧ポートに出力する。 In the first electromagnetic proportional control valve 22R, which is one of the two electromagnetic proportional control valves 22R and 22L, the primary pressure port is selectively connected to either the sub pump 13 or the tank 12, and the secondary pressure port is the first It is connected to the switching valve 24R. In addition, the first solenoid proportional control valve 22R can be supplied with current (that is, the first command signal is input) to the solenoid part 22Ra, and is opened according to the current supplied to the solenoid part 22Ra. It is designed to switch degrees. That is, the first electromagnetic proportional control valve 22R is a direct proportional electromagnetic proportional control valve, and the sub pump 13 and the secondary pressure port are connected by supplying a current to the solenoid section 22Ra, and the sub pump 13 and the secondary pressure port Is opened at an opening degree corresponding to the current flowing to the solenoid portion 22Ra. On the other hand, when the current flowing to the solenoid portion 22Ra is stopped, the sub pump 13 and the valve secondary pressure port are shut off, and the valve secondary pressure port is connected to the tank 12. The first electromagnetic proportional control valve 22R configured in this manner controls the pressure of the sub pump discharge pressure pp to a pressure (first output pressure psR) according to the current flowing to the solenoid section 22Ra, and outputs it to the secondary pressure port Do.
　２つの電磁比例制御弁２２Ｒ，２２Ｌのうちの他方である第２電磁比例制御弁２２Ｌは、第１電磁比例制御弁２２Ｒと同様の構造を有しており、一次圧ポートがサブポンプ１３及びタンク１２の何れかに選択的に接続され、二次圧ポートが第２切換弁２４Ｌに接続されている。即ち、第２電磁比例制御弁２２Ｌは、正比例型の電磁比例制御弁であり、ソレノイド部２２Ｌａに電流を流すことによってサブポンプ１３と二次圧ポートとが接続され、サブポンプ１３と二次圧ポートとの間がソレノイド部２２Ｌａに流れる電流に応じた開度で開かれる。他方、ソレノイド部２２Ｌａに流れる電流が止められると、サブポンプ１３と二次圧ポート弁との間が遮断されて二次圧ポート弁がタンク１２と接続される。このように構成されている第２電磁比例制御弁２２Ｌは、サブポンプ吐出圧ｐｐをソレノイド部２２Ｌａに流される電流に応じた圧力（即ち、第２出力圧ｐｓＬ）に減圧制御して二次圧ポートに出力する。 The second electromagnetic proportional control valve 22L, which is the other of the two electromagnetic proportional control valves 22R and 22L, has the same structure as the first electromagnetic proportional control valve 22R, and the primary pressure port is the sub pump 13 and the tank 12 And the secondary pressure port is connected to the second switching valve 24L. That is, the second electromagnetic proportional control valve 22L is a direct proportional electromagnetic proportional control valve, and the sub pump 13 and the secondary pressure port are connected by supplying a current to the solenoid unit 22La, and the sub pump 13 and the secondary pressure port Is opened at an opening degree corresponding to the current flowing to the solenoid portion 22La. On the other hand, when the current flowing to the solenoid part 22La is stopped, the sub pump 13 and the secondary pressure port valve are shut off, and the secondary pressure port valve is connected to the tank 12. The second electromagnetic proportional control valve 22L configured in this way controls the sub pump discharge pressure pp to a pressure (that is, the second output pressure psL) corresponding to the current flowing to the solenoid section 22La, and the secondary pressure port Output to
　このような構成されている２つの電磁比例制御弁２２Ｒ，２２Ｌは、以下のような機能を有する。即ち、２つの切換弁２４Ｒ，２４Ｌの各々には、２つの電磁比例制御弁２２Ｒ，２２Ｌから出力される出力圧ｐｓＲ，ｐｓＬが入力されるようになっている。また、第１切換弁２４Ｒには、第１電磁比例制御弁２２Ｒの二次圧ポートの他にサブポンプ１３及び流量制御弁２１の第１パイロットポート２１Ｒが接続され、第２切換弁２４Ｌには、第２電磁比例制御弁２２Ｌの二次圧ポートの他にサブポンプ１３及び流量制御弁２１の第２パイロットポート２１Ｌが接続されている。このように接続されている第１切換弁２４Ｒ及び第２切換弁２４Ｌは、以下のように構成されている。 The two electromagnetic proportional control valves 22R and 22L configured as described above have the following functions. That is, the output pressures psR and psL output from the two electromagnetic proportional control valves 22R and 22L are input to the two switching valves 24R and 24L, respectively. In addition to the secondary pressure port of the first electromagnetic proportional control valve 22R, the sub pump 13 and the first pilot port 21R of the flow control valve 21 are connected to the first switching valve 24R, and the second switching valve 24L is connected to the second switching valve 24L. In addition to the secondary pressure port of the second electromagnetic proportional control valve 22L, the sub pump 13 and the second pilot port 21L of the flow control valve 21 are connected. The first switching valve 24R and the second switching valve 24L thus connected are configured as follows.
　第１切換弁２４Ｒは、第１パイロット通路２３Ｒを介して流量制御弁２１の第１パイロットポート２１Ｒに接続され、流量制御弁２１に入力される第１パイロット圧ｐｉＲを切換えるようになっている。即ち、第１切換弁２４Ｒは、第１位置Ｍ１Ｒ及び第２位置Ｍ２Ｒとの間で移動可能なスプール２４Ｒａを有しており、スプール２４Ｒａが第１位置Ｍ１Ｒに位置する状態で第１電磁比例制御弁２２Ｒの二次ポートと第１パイロットポート２１Ｒとを接続する。これにより、第１電磁比例制御弁２２Ｒの二次圧である第１出力圧ｐｓＲが第１パイロット圧ｐｉＲとして流量制御弁２１に出力される。他方、スプール２４Ｒａが第２位置Ｍ２Ｒに位置する状態では、サブポンプ１３と第１パイロットポート２１Ｒとが接続され、サブポンプ１３のサブポンプ吐出圧ｐｐが第１パイロット圧ｐｉＲとして流量制御弁２１に出力される。 The first switching valve 24R is connected to the first pilot port 21R of the flow control valve 21 via the first pilot passage 23R, and switches the first pilot pressure piR input to the flow control valve 21. That is, the first switching valve 24R has the spool 24Ra movable between the first position M1R and the second position M2R, and the first electromagnetic proportional control is performed with the spool 24Ra positioned at the first position M1R. The secondary port of the valve 22R and the first pilot port 21R are connected. As a result, the first output pressure psR, which is the secondary pressure of the first electromagnetic proportional control valve 22R, is output to the flow control valve 21 as the first pilot pressure piR. On the other hand, when the spool 24Ra is located at the second position M2R, the sub pump 13 and the first pilot port 21R are connected, and the sub pump discharge pressure pp of the sub pump 13 is output to the flow control valve 21 as the first pilot pressure piR. .
　また、第２切換弁２４Ｌは、第２パイロット通路２３Ｌを介して流量制御弁２１の第２パイロットポート２１Ｌに接続され、流量制御弁２１に入力される第２パイロット圧ｐｉＬを切換えるようになっている。即ち、第２切換弁２４Ｌは、第１位置Ｍ１Ｌ及び第２位置Ｍ２Ｌとの間で切換可能なスプール２４Ｌａを有しており、スプール２４Ｌａが第１位置Ｍ１Ｌに位置する状態で第２電磁比例制御弁２２Ｌの二次ポートと第２パイロットポート２１Ｌとを接続する。これにより、第２電磁比例制御弁２２Ｌの第２出力圧ｐｓＬが第１パイロット圧ｐｉＬとして流量制御弁２１に出力される。他方、スプール２４Ｌａが第２位置Ｍ２Ｌに位置する状態では、サブポンプ１３と第２パイロットポート２１Ｌとが接続され、サブポンプ吐出圧ｐｐが第２パイロット圧ｐｉＬとして流量制御弁２１に出力する。 Further, the second switching valve 24L is connected to the second pilot port 21L of the flow control valve 21 through the second pilot passage 23L, and switches the second pilot pressure piL input to the flow control valve 21. There is. That is, the second switching valve 24L has a spool 24La switchable between the first position M1L and the second position M2L, and the second electromagnetic proportional control is performed with the spool 24La positioned at the first position M1L. The secondary port of the valve 22L and the second pilot port 21L are connected. Thus, the second output pressure psL of the second electromagnetic proportional control valve 22L is output to the flow control valve 21 as the first pilot pressure piL. On the other hand, when the spool 24La is positioned at the second position M2L, the sub pump 13 and the second pilot port 21L are connected, and the sub pump discharge pressure pp is output to the flow control valve 21 as the second pilot pressure piL.
　また、第１パイロット通路２３Ｒは、その途中で分岐するように第１油通路２５Ｒに接続され、第１油通路２５Ｒは、第２切換弁２４Ｌに接続されている。第１油通路２５Ｒは、第２切換弁２４Ｌのスプール２４Ｌａに第１パイロット圧ｐｉＲを与える。また、第２切換弁２４Ｌのスプール２４Ｌａには、第１パイロット圧ｐｉＲに抗する方向に第２電磁比例制御弁２２Ｌから出力される第２出力圧ｐｓＬが作用している。それ故、第２切換弁２４Ｌのスプール２４Ｌａは、第２出力圧ｐｓＬと第１パイロット圧ｐｉＲとの差圧に応じて移動し、その位置を切換えるようになっている。また、第２切換弁２４Ｌのスプール２４Ｌａには、第１パイロット圧ｐｉＲに抗する方向に付勢力を与えるばね２４Ｌｂが設けられている。それ故、スプール２４Ｌａは、第１パイロット圧ｐｉＲから第２出力圧ｐｓＬを減算して得られる差圧が第２所定圧力ｐｓ２未満である場合、第１位置Ｍ１Ｌに位置し、第２出力圧ｐｓＬを第２パイロット圧ｐｉＬとして流量制御弁２１に出力される。他方、前記差分が第２所定圧力ｐｓ２以上である場合、スプール２４Ｌａが第２位置Ｍ２Ｌに位置する。これにより、サブポンプ吐出圧ｐｐが第２パイロット圧ｐｉＬとして流量制御弁２１に出力される。 Further, the first pilot passage 23R is connected to the first oil passage 25R so as to branch along the way, and the first oil passage 25R is connected to the second switching valve 24L. The first oil passage 25R applies a first pilot pressure piR to the spool 24La of the second switching valve 24L. Further, the second output pressure psL output from the second electromagnetic proportional control valve 22L acts on the spool 24La of the second switching valve 24L in a direction that opposes the first pilot pressure piR. Therefore, the spool 24La of the second switching valve 24L moves in accordance with the differential pressure between the second output pressure psL and the first pilot pressure piR, and switches its position. Further, the spool 24La of the second switching valve 24L is provided with a spring 24Lb that applies a biasing force in a direction that opposes the first pilot pressure piR. Therefore, when the differential pressure obtained by subtracting the second output pressure psL from the first pilot pressure piR is less than the second predetermined pressure ps2, the spool 24La is located at the first position M1L and the second output pressure psL Are output to the flow control valve 21 as the second pilot pressure piL. On the other hand, when the difference is equal to or greater than the second predetermined pressure ps2, the spool 24La is positioned at the second position M2L. As a result, the sub pump discharge pressure pp is output to the flow control valve 21 as the second pilot pressure piL.
　なお、第２所定圧力ｐｓ２は、スプール２４Ｌａを付勢するばね２４Ｌｂの付勢力に応じて決まる圧力であって、以下のように設定されている。即ち、第２所定圧力ｐｓ２は、第１パイロット圧ｐｉＲをスプール２１ａに作用させてスプール２１ａを最大ストローク量までストロークさせるのに必要な圧力ｐｍ１より大きく且つサブポンプ吐出圧ｐｐより小さい圧力に設定されている。なお、本実施形態において、第２所定圧力ｐｓ２は、第１所定圧力ｐｓ１と同じ圧力に設定されている。 The second predetermined pressure ps2 is a pressure determined according to the biasing force of the spring 24Lb that biases the spool 24La, and is set as follows. That is, the second predetermined pressure ps2 is set to a pressure that is larger than the pressure pm1 required to cause the spool 21a to stroke to the maximum stroke amount by causing the first pilot pressure piR to act on the spool 21a and smaller than the sub pump discharge pressure pp There is. In the present embodiment, the second predetermined pressure ps2 is set to the same pressure as the first predetermined pressure ps1.
　また、第２パイロット通路２３Ｌは、その途中で分岐するように第２油通路２５Ｌに接続され、第２油通路２５Ｌは第１切換弁２４Ｒに接続されている。第２油通路２５Ｌは、第１切換弁２４Ｒのスプール２４Ｒａに第２パイロット圧ｐｉＬを与える。また、第１切換弁２４Ｒのスプール２４Ｒａには、第２パイロット圧ｐｉＬに抗する方向に第１電磁比例制御弁２２Ｒから出力される第１出力圧ｐｓＲが作用している。それ故、第１切換弁２４Ｒのスプール２４Ｒａは、第１出力圧ｐｓＲと第２パイロット圧ｐｉＬとの差圧に応じて移動し、その位置を切換えるようになっている。また、第１切換弁２４Ｒのスプール２４Ｒａには、第２パイロット圧ｐｉＬに抗する方向に付勢力を与えるばね２４Ｒｂが設けられている。それ故、スプール２４Ｒａは、第２パイロット圧ｐｉＬから第１出力圧ｐｓＲを減算して得られる差圧が第１所定圧力ｐｓ１未満であると第１位置Ｍ１Ｒに位置し、第１出力圧ｐｓＲを第１パイロット圧ｐｉＲとして流量制御弁２１に出力する。他方、前記差分が第１所定圧力以上である場合、スプール２４Ｒａが第２位置Ｍ２Ｒに位置する。これにより、サブポンプ吐出圧ｐｐが第１パイロット圧ｐｉＲとして流量制御弁２１に出力される。 Further, the second pilot passage 23L is connected to the second oil passage 25L so as to branch along the way, and the second oil passage 25L is connected to the first switching valve 24R. The second oil passage 25L applies a second pilot pressure piL to the spool 24Ra of the first switching valve 24R. Further, the first output pressure psR output from the first electromagnetic proportional control valve 22R acts on the spool 24Ra of the first switching valve 24R in a direction that opposes the second pilot pressure piL. Therefore, the spool 24Ra of the first switching valve 24R moves in accordance with the differential pressure between the first output pressure psR and the second pilot pressure piL, and switches its position. Further, the spool 24Ra of the first switching valve 24R is provided with a spring 24Rb that applies a biasing force in a direction that opposes the second pilot pressure piL. Therefore, the spool 24Ra is positioned at the first position M1R if the differential pressure obtained by subtracting the first output pressure psR from the second pilot pressure piL is less than the first predetermined pressure ps1, and the first output pressure psR The first pilot pressure piR is output to the flow control valve 21. On the other hand, when the difference is equal to or more than the first predetermined pressure, the spool 24Ra is located at the second position M2R. As a result, the sub pump discharge pressure pp is output to the flow control valve 21 as the first pilot pressure piR.
　なお、第１所定圧力ｐｓ１は、スプール２４Ｒａを付勢するばね２４Ｒｂの付勢力に応じて決まる圧力であって、以下のように設定されている。即ち、第１所定圧力ｐｓ１は、第２パイロット圧ｐｉＬをスプール２１ａに作用させてスプール２１ａを最大ストローク量までストロークさせるのに必要な圧力ｐｍ２より大きく且つサブポンプ１３の吐出圧ｐｐより小さい圧力に設定されている（図２のグラフ参照）。なお、図２のグラフは、横軸にパイロット圧ｐｉＲ，ｐｉＬ、縦軸にスプール２４Ｒａのストローク量が示されている。 The first predetermined pressure ps1 is a pressure determined according to the biasing force of the spring 24Rb that biases the spool 24Ra, and is set as follows. That is, the first predetermined pressure ps1 is set to a pressure which is larger than the pressure pm2 necessary for causing the second pilot pressure piL to act on the spool 21a and causing the spool 21a to stroke to the maximum stroke amount and smaller than the discharge pressure pp of the sub pump 13. (See the graph in Figure 2). In the graph of FIG. 2, the horizontal axis represents the pilot pressure piR, piL, and the vertical axis represents the stroke amount of the spool 24Ra.
　このように構成されている油圧駆動装置１４は、前述の通り、２つの電磁比例制御弁２２Ｒ，２２Ｌに電流を流すことができるようになっており、電流を流すことによって流量制御弁２１のスプール２１ａの位置を制御するようになっている。このように構成される２つの電磁比例制御弁２２Ｒ，２２Ｌには、それらに電流を流してそれらの動きを制御すべく制御ユニット２６が電気的に接続され、また制御ユニット２６には、操作装置２７が電気的に接続されている。操作装置２７は、操作レバー２７ａを有しており、操作レバー２７ａは、互いに相反する第１方向Ａ１及び第２方向Ａ２に操作可能（より具体的には、傾倒可能）に構成されている。また、操作装置２７は、操作レバー２７ａの操作方向及び操作量（即ち、傾倒量）に応じた操作指令を制御ユニット２６に出力するようになっている。 As described above, the hydraulic drive device 14 configured in this way is capable of supplying current to the two electromagnetic proportional control valves 22R and 22L, and the spool of the flow control valve 21 is generated by causing the current to flow. The position of 21a is to be controlled. A control unit 26 is electrically connected to the two electromagnetic proportional control valves 22R, 22L configured in this way so as to supply current to them and control their movement, and the control unit 26 has an operating device 27 are electrically connected. The operating device 27 has an operating lever 27a, and the operating lever 27a is configured to be operable (more specifically, tiltable) in mutually opposing first direction A1 and second direction A2. The operating device 27 is also configured to output to the control unit 26 an operating command according to the operating direction and the operating amount (i.e., the amount of tilting) of the operating lever 27a.
　制御ユニット２６は、第１電磁比例制御弁２２Ｒ、第２電磁比例制御弁２２Ｌ、及びレギュレータ１５に電気的に接続され、操作装置２７からの操作指令に応じてこれらの動きを制御するようになっている。即ち、制御ユニット２６は、レギュレータ１５を作動させ、斜板１１ｄの傾転角を操作レバー２７ａの操作量に応じた傾転角に調整する。また、制御ユニット２６は、操作レバー２７ａの操作方向に応じて２つの電磁比例制御弁２２Ｒ，２２Ｌの何れかを制御し、操作レバー２７ａの操作方向に応じた方向で且つ操作量に応じた流量の作動油を油圧アクチュエータ２に供給するようになっている。 The control unit 26 is electrically connected to the first electromagnetic proportional control valve 22R, the second electromagnetic proportional control valve 22L, and the regulator 15, and controls these movements in response to an operation command from the operating device 27. ing. That is, the control unit 26 operates the regulator 15 to adjust the tilt angle of the swash plate 11 d to a tilt angle according to the amount of operation of the control lever 27 a. Further, the control unit 26 controls either of the two electromagnetic proportional control valves 22R and 22L according to the operation direction of the control lever 27a, and the flow rate according to the operation amount in the direction according to the operation direction of the control lever 27a. Is supplied to the hydraulic actuator 2.
　また、制御ユニット２６は、第１電磁比例制御弁２２Ｒ及び第２電磁比例制御弁２２Ｌの故障を検出すべく、以下のように動作している。即ち、制御ユニット２６は、第１電磁比例制御弁２２Ｒ及び第２電磁比例制御弁２２Ｌへ流れる電流の値を検出し、電磁比例制御弁２２Ｒ，２２Ｌの配線経路（即ち、第１及び第２電磁比例制御弁２２Ｒ、２２Ｌの各々に対して、制御ユニット２６に繋がるハーネス、接続部分、及びソレノイド部２２Ｒａ，２２Ｌａ）の通電状態を検出し、各配線経路における通電不良（即ち、配線経路における断線及びショートの発生）を検知している。更に、制御ユニット２６は、図示しない圧力センサを用いてメインポンプ１１の吐出圧ｐを検出し、検出した吐出圧ｐと操作レバー２７ａの操作量との関係から第１電磁比例制御弁２２Ｒ及び第２電磁比例制御弁２２Ｌの弁体が供給した電流値に応じた動作をしているか否か（即ち、スティックの発生の有無）を検知できるようになっている。 The control unit 26 also operates as follows to detect a failure of the first electromagnetic proportional control valve 22R and the second electromagnetic proportional control valve 22L. That is, the control unit 26 detects the value of the current flowing to the first electromagnetic proportional control valve 22R and the second electromagnetic proportional control valve 22L, and the wiring paths of the electromagnetic proportional control valves 22R and 22L (ie, the first and second electromagnetic For each of the proportional control valves 22R and 22L, the conduction state of the harness connected to the control unit 26, the connection portion, and the solenoid portions 22Ra and 22La) is detected, and the conduction failure in each wiring path (ie, disconnection in the wiring path and Detection of a short). Furthermore, the control unit 26 detects the discharge pressure p of the main pump 11 using a pressure sensor (not shown), and the relationship between the detected discharge pressure p and the operation amount of the control lever 27a causes the first electromagnetic proportional control valve 22R and 2) It is possible to detect whether or not the valve element of the electromagnetic proportional control valve 22L operates according to the supplied current value (that is, the presence or absence of the occurrence of the stick).
　［油圧駆動システムの動作］
　以上のように構成される油圧駆動システム１は、操作レバー２７ａの操作量に応じた方向且つ流量の作動油を油圧アクチュエータ２に供給することができる。即ち、操作レバー２７ａの操作量に応じた方向、且つ速度で油圧アクチュエータ２を駆動することができる。例えば、操作レバー２７ａが第２方向Ａ２に操作されると、操作される方向及び操作レバー２７ａの操作量に応じた操作指令が操作装置２７から制御ユニット２６に出力される。制御ユニット２６は、この操作指令に応じた電流を第２電磁比例制御弁２２Ｌのソレノイド部２２Ｌａに流す。これにより、操作レバー２７ａの操作量に応じた第２出力圧ｐｓＬが第２電磁比例制御弁２２Ｌから第２切換弁２４Ｌに出力される。 [Operation of hydraulic drive system]
The hydraulic drive system 1 configured as described above can supply the hydraulic actuator 2 with hydraulic fluid in a direction and at a flow rate corresponding to the amount of operation of the control lever 27a. That is, the hydraulic actuator 2 can be driven in the direction according to the amount of operation of the control lever 27a and at the speed. For example, when the operation lever 27a is operated in the second direction A2, an operation command according to the operated direction and the operation amount of the operation lever 27a is output from the operation device 27 to the control unit 26. The control unit 26 supplies a current corresponding to the operation command to the solenoid section 22La of the second electromagnetic proportional control valve 22L. As a result, the second output pressure psL corresponding to the operation amount of the control lever 27a is output from the second electromagnetic proportional control valve 22L to the second switching valve 24L.
　第２切換弁２４Ｌでは、そのスプール２４Ｌａが第１出力圧ｐｓＲと第２パイロット圧ｐｉＬとの差圧に応じて位置を変える。第１パイロット圧ｐｉＲは、第１電磁比例制御弁２２Ｒの第１出力圧ｐｓＲ及び第１切換弁２４Ｒのスプール２４Ｒａの位置に応じて変動する。操作レバー２７ａが第２方向Ａ２に操作された場合、第１出力圧ｐｓＲは基本的にタンク圧となっており、第１切換弁２４Ｒのスプール２４Ｒａの位置は、第２パイロット圧ｐｉＬが第１所定圧力ｐｓ１以上か否かによって決まる。前述の通り、流量制御弁２１のスプール２１ａは、第２パイロット圧ｐｉＬが圧力ｐｍ２に達すると最大ストローク量までストロークするようになっている。それ故、制御ユニット２６は、後述するような場合（即ち、第２電磁比例制御弁２２Ｌの故障）を除いて、第２出力圧ｐｓＬが０≦ｐｓＬ≦ｐｍ２の範囲内となるように制御されており、その結果第２パイロット圧ｐｉＬが０≦ｐｉＬ≦ｐｍ２の範囲内で制御されている。即ち、第２パイロット圧ｐｉＬは、基本的に第１所定圧力ｐｓ１未満となっており、第１切換弁２４Ｒのスプール２４Ｒａは第１位置Ｍ１Ｒに位置し、第１パイロット圧ｐｉＲはタンク圧にて維持されている。 In the second switching valve 24L, the spool 24La changes its position according to the differential pressure between the first output pressure psR and the second pilot pressure piL. The first pilot pressure piR fluctuates according to the first output pressure psR of the first electromagnetic proportional control valve 22R and the position of the spool 24Ra of the first switching valve 24R. When the control lever 27a is operated in the second direction A2, the first output pressure psR is basically the tank pressure, and the position of the spool 24Ra of the first switching valve 24R is the first pilot pressure piL It depends on whether or not the predetermined pressure ps1 or more. As described above, the spool 21a of the flow control valve 21 is configured to stroke up to the maximum stroke amount when the second pilot pressure piL reaches the pressure pm2. Therefore, the control unit 26 is controlled such that the second output pressure psL is in the range of 0 ≦ psL ≦ pm2, except in the case described later (ie, failure of the second electromagnetic proportional control valve 22L). As a result, the second pilot pressure piL is controlled within the range of 0 ≦ piL ≦ pm2. That is, the second pilot pressure piL is basically less than the first predetermined pressure ps1, the spool 24Ra of the first switching valve 24R is located at the first position M1R, and the first pilot pressure piR is the tank pressure. It is maintained.
　第１パイロット圧ｐｉＲがタンク圧に維持されることによって、第１パイロット圧ｐｉＲから第２出力圧ｐｓＬを減算した差圧が第２所定圧力ｐｓ２未満となり、第２切換弁２４Ｌのスプール２４Ｌａもまた第１位置Ｍ１Ｌに位置する。これにより、第２出力圧ｐｓＬが第２パイロット圧ｐｉＬとして第２切換弁２４Ｌから流量制御弁２１に出力され、流量制御弁２１のスプール２１ａが第２パイロット圧ｐｉＬに応じた位置、即ち操作レバー２７ａの操作量に応じた位置に移動する。移動することによって操作レバー２７ａが操作された方向、即ち油圧アクチュエータ２の第２ポート２ｂに操作レバー２７ａの操作量に応じた流量の作動油が導かれる。これによって、操作レバー２７ａの操作量に応じた速度で油圧アクチュエータ２を収縮させることができる。 By maintaining the first pilot pressure piR at the tank pressure, the differential pressure obtained by subtracting the second output pressure psL from the first pilot pressure piR becomes less than the second predetermined pressure ps2, and the spool 24La of the second switching valve 24L also becomes Located at the first position M1L. As a result, the second output pressure psL is output as the second pilot pressure piL from the second switching valve 24L to the flow control valve 21, and the spool 21a of the flow control valve 21 corresponds to the second pilot pressure piL, that is, the operation lever Move to the position according to the operation amount of 27a. By moving, the hydraulic oil having a flow rate corresponding to the amount of operation of the control lever 27a is guided to the direction in which the control lever 27a is operated, that is, the second port 2b of the hydraulic actuator 2. Thus, the hydraulic actuator 2 can be contracted at a speed corresponding to the amount of operation of the control lever 27a.
　なお、操作レバー２７ａが第１方向Ａ１に操作される場合については、第２方向Ａ２に操作される場合と同様の動作であるので詳しくは説明しないが、第１方向Ａ１に操作される場合もまた操作装置２７から制御ユニット２６に操作指令が出力される。制御ユニット２６は、この操作指令に応じた電流を第１電磁比例制御弁２２Ｒのソレノイド部２２Ｒａに流す。そうすると、第１出力圧ｐｓＲは、第１切換弁２４Ｒを介して流量制御弁２１に出力され、即ち、第１出力圧ｐｓＲが第１パイロット圧ｐｉＲとして流量制御弁２１に入力される。これにより、操作レバー２７ａが第１方向Ａ１に操作された場合、油圧アクチュエータ２の第１ポート２ａに操作レバー２７ａの操作量に応じた流量の作動油が導かれる。これによって、操作レバー２７ａの操作量に応じた速度で油圧アクチュエータ２を伸長させることができる。 The operation when the operation lever 27a is operated in the first direction A1 is the same as the operation when operated in the second direction A2 and thus will not be described in detail, but the operation may be performed when the operation lever 27a is operated in the first direction A1. Further, an operation command is output from the operating device 27 to the control unit 26. The control unit 26 supplies a current corresponding to the operation command to the solenoid section 22Ra of the first electromagnetic proportional control valve 22R. Then, the first output pressure psR is output to the flow control valve 21 via the first switching valve 24R, that is, the first output pressure psR is input to the flow control valve 21 as a first pilot pressure piR. As a result, when the control lever 27a is operated in the first direction A1, hydraulic fluid having a flow rate corresponding to the amount of operation of the control lever 27a is guided to the first port 2a of the hydraulic actuator 2. As a result, the hydraulic actuator 2 can be extended at a speed corresponding to the amount of operation of the control lever 27a.
　［故障時の動作］
　このように動作する油圧駆動システム１は、第１電磁比例制御弁２２Ｒ及び第２電磁比例制御弁２２Ｌの何れかが故障した場合において、以下のように動作するようになっている。ここで故障としては、通電不良及び弁体のスティックに起因して第２電磁比例制御弁２２Ｌの第２出力圧ｐｓＬ（又は第１電磁比例制御弁２２Ｒの第１出力圧ｐｓＲ）がゼロに維持されるような故障、並びに弁体のスティックに起因して第２電磁比例制御弁２２Ｌの第２出力圧ｐｓＬ（又は第１電磁比例制御弁２２Ｒの第１出力圧ｐｓＲ）がサブポンプ吐出圧ｐｐに維持されるような故障が想定される。以下では、第２電磁比例制御弁２２Ｌの第２出力圧ｐｓＬ（又は第１電磁比例制御弁２２Ｒの第１出力圧ｐｓＲ）がゼロに維持されるような故障であって、第２電磁比例制御弁２２Ｌ（又は第１電磁比例制御弁２２Ｒ）の配線経路に故障（即ち、断線及びショート）が生じて第２電磁比例制御弁２２Ｌ（又は第１電磁比例制御弁２２Ｒ）に通電できない場合を例にして説明する。 [Operation at the time of failure]
The hydraulic drive system 1 that operates in this manner operates as follows when any of the first electromagnetic proportional control valve 22R and the second electromagnetic proportional control valve 22L fails. Here, as a failure, the second output pressure psL of the second electromagnetic proportional control valve 22L (or the first output pressure psR of the first electromagnetic proportional control valve 22R) is maintained at zero due to the electrification failure and the stick of the valve body. The second output pressure psL of the second solenoid proportional control valve 22L (or the first output pressure psR of the first solenoid proportional control valve 22R) to the sub pump discharge pressure pp due to the failure of the valve body and the stick of the valve body It is assumed that the failure is maintained. In the following, the second output pressure psL of the second electromagnetic proportional control valve 22L (or the first output pressure psR of the first electromagnetic proportional control valve 22R) is maintained at zero, the second electromagnetic proportional control An example where a failure (that is, disconnection or short circuit) occurs in the wiring path of the valve 22L (or the first electromagnetic proportional control valve 22R) and the second electromagnetic proportional control valve 22L (or the first electromagnetic proportional control valve 22R) can not be energized To explain.
　なお、油圧駆動システム１では、第１電磁比例制御弁２２Ｒ及び第２電磁比例制御弁２２Ｌの何れか一方において配線経路に故障が生じた場合でも、故障が生じていない他方を作動させることによって油圧アクチュエータ２を駆動させるようになっている。それ故、以下では第２電磁比例制御弁２２Ｌの配線経路に故障が生じて通電できない場合について説明し、第１電磁比例制御弁２２Ｒの配線経路に故障が生じて通電できない場合については説明を省略する。 In the hydraulic drive system 1, even when a failure occurs in the wiring path in either one of the first electromagnetic proportional control valve 22R and the second electromagnetic proportional control valve 22L, the hydraulic pressure is generated by operating the other without any failure. The actuator 2 is driven. Therefore, hereinafter, the case where a failure occurs in the wiring path of the second electromagnetic proportional control valve 22L and the current can not be supplied will be described, and the description will be omitted in the case where the wiring route of the first electromagnetic proportional control valve 22R causes the failure Do.
　制御ユニット２６は、第２電磁比例制御弁２２Ｌに通電する際の電流の値を検知している。それ故、操作指令に応じた指令電流（即ち、前記制御ユニットが指示した電流値）と実際に検知された電流の値（即ち、第２電磁比例制御弁に実際に流れた電流値）とが異なる場合、例えば第２電磁比例制御弁２２Ｌに通電しようとしいるにもかかわらず電流の値が検知されない場合、制御ユニット２６は、第２電磁比例制御弁２２Ｌにおける配線経路に故障があると判断する。配線経路に故障が生じた場合、第２電磁比例制御弁２２Ｌが正比例型の電磁弁であるので、操作レバー２７ａの操作に関わらず第２切換弁２４Ｌとタンク１２とが連通している状態が維持されている。他方、第１電磁比例制御弁２２Ｒが正常に動作する場合には、第１出力圧ｐｓＲが０≦ｐｓＲ≦ｐｍ１の範囲内で制御可能であるので、第２切換弁２４Ｌのスプール２４Ｌａは第１位置Ｍ１Ｌにて留めることができる。即ち、第２パイロット圧ｐｉＬがタンク圧に維持されている。それ故、操作レバー２７ａが第１方向Ａ１に操作された場合、制御ユニット２６は、第２電磁比例制御弁２２Ｌにおける配線経路に故障が生じていない場合と同様に、０≦ｐｓＲ≦ｐｍ１の範囲内で第１電磁比例制御弁２２Ｒを制御し、操作レバー２７ａの操作量に応じた速度で油圧アクチュエータ２を伸長させることができる（図３のグラフの有効パイロット範囲（０≦ｐｓＲ≦ｐｍ１）を参照）。なお、図３は、横軸が出力圧ｐｓＲを示し、縦軸の上側が第１パイロット圧ｐｉＲを示し、縦軸の下側が第２パイロット圧ｐｉＬを示している。 The control unit 26 detects the value of the current when the second electromagnetic proportional control valve 22L is energized. Therefore, the command current corresponding to the operation command (ie, the current value instructed by the control unit) and the value of the actually detected current (ie, the current value actually flowing to the second electromagnetic proportional control valve) are If different, for example, if it is attempted to energize the second electromagnetic proportional control valve 22L and the value of the current is not detected, the control unit 26 determines that the wiring path in the second electromagnetic proportional control valve 22L has a fault. . When a failure occurs in the wiring path, the second switching valve 24L and the tank 12 are in communication regardless of the operation of the control lever 27a because the second solenoid proportional control valve 22L is a direct proportional type solenoid valve. It is maintained. On the other hand, since the first output pressure psR can be controlled within the range of 0 ≦ psR ≦ pm1 when the first electromagnetic proportional control valve 22R operates normally, the spool 24La of the second switching valve 24L is the first It can be stopped at position M1L. That is, the second pilot pressure piL is maintained at the tank pressure. Therefore, when the control lever 27a is operated in the first direction A1, the control unit 26 is in the range of 0 ≦ psR ≦ pm1 as in the case where no failure occurs in the wiring path in the second electromagnetic proportional control valve 22L. It is possible to control the first electromagnetic proportional control valve 22R and extend the hydraulic actuator 2 at a speed according to the operation amount of the control lever 27a (the effective pilot range (0 ≦ psR ≦ pm1 in the graph of FIG. 3)). reference). In FIG. 3, the horizontal axis indicates the output pressure psR, the upper side of the vertical axis indicates the first pilot pressure piR, and the lower side of the vertical axis indicates the second pilot pressure piL.
　他方、操作レバー２７ａが第２方向Ａ２に操作された場合には、第２電磁比例制御弁２２Ｌに通電できないので、制御ユニット２６は、第１電磁比例制御弁２２Ｒを用いて以下のように油圧アクチュエータ２を収縮させる。即ち、制御ユニット２６は、操作レバー２７ａが第２方向Ａ２に操作されて操作装置２７から操作信号を受けると、第１出力圧ｐｓＲが第２所定圧力ｐｓ２以上となるように第１電磁比例制御弁２２Ｒの動作を制御する。これにより、第２所定圧力ｐｓ２以上の第１出力圧ｐｓＲが第１パイロット圧ｐｉＲとして第１切換弁２４Ｒから出力され、第１パイロット圧ｐｉＲが第２所定圧力ｐｓ２以上となる。また、第１パイロット圧ｐｉＲが第２所定圧力ｐｓ２以上となることによって、第２切換弁２４Ｌのスプール２４Ｌａが第２位置Ｍ２Ｌに移動し、第２切換弁２４Ｌによってサブポンプ１３と流量制御弁２１の第２パイロットポート２１Ｌとが繋がる。即ち、サブポンプ１３のサブポンプ吐出圧ｐｐが第２パイロット圧ｐｉＬとして第２切換弁２４Ｌから出力される。これにより、流量制御弁２１のスプール２１ａには、第１パイロット圧ｐｉＲより大きい第２パイロット圧ｐｉＬを第１パイロット圧ｐｉＲに抗するように作用させることができ、その差圧に基づいてスプール２１ａを第２オフセット位置Ｍ２の方へと移動させることができる。即ち、操作レバー２７ａの第２方向Ａ２への操作に応じて油圧アクチュエータ２の第２ポート２ｂに作動油を流してシリンダを収縮させることができる。 On the other hand, when the control lever 27a is operated in the second direction A2, since the second electromagnetic proportional control valve 22L can not be energized, the control unit 26 uses the first electromagnetic proportional control valve 22R to perform hydraulic pressure as follows. The actuator 2 is contracted. That is, when the operation lever 27a is operated in the second direction A2 and the operation signal is received from the operation device 27, the control unit 26 performs the first electromagnetic proportional control so that the first output pressure psR becomes equal to or higher than the second predetermined pressure ps2. Control the operation of the valve 22R. As a result, the first output pressure psR equal to or higher than the second predetermined pressure ps2 is output from the first switching valve 24R as the first pilot pressure piR, and the first pilot pressure piR becomes equal to or higher than the second predetermined pressure ps2. Further, when the first pilot pressure piR becomes equal to or higher than the second predetermined pressure ps2, the spool 24La of the second switching valve 24L moves to the second position M2L, and the second switching valve 24L causes the sub pump 13 and the flow control valve 21 to The second pilot port 21L is connected. That is, the sub pump discharge pressure pp of the sub pump 13 is output from the second switching valve 24L as the second pilot pressure piL. As a result, the second pilot pressure piL larger than the first pilot pressure piR can be applied to the spool 21a of the flow control valve 21 so as to withstand the first pilot pressure piR, and the spool 21a can be operated based on the differential pressure. Can be moved toward the second offset position M2. That is, in response to the operation of the control lever 27a in the second direction A2, hydraulic oil can be caused to flow through the second port 2b of the hydraulic actuator 2 to contract the cylinder.
　また、制御ユニット２６は、図３のグラフに示すように操作レバー２７ａの操作量に応じて出力圧ｐｓＲを制御し、操作レバー２７ａの操作量に応じた流量の作動油が油圧アクチュエータ２に流れるようにスプール２１ａの位置を調整する。即ち、スプール２１ａは、２つのパイロット圧ｐｉＲ，ｐｉＬの差圧に応じた位置に移動するようになっており、第１出力圧ｐｓＲを調整することによって２つのパイロット圧ｐｉＲ，ｐｉＬの差圧Δｐ（図３の二点鎖線）を調整して操作レバー２７ａの操作量に応じた位置、即ち第２オフセット位置Ｍ２の方へとスプール２１ａを移動させる。 Further, the control unit 26 controls the output pressure psR in accordance with the amount of operation of the control lever 27a as shown in the graph of FIG. 3, and hydraulic oil of a flow rate corresponding to the amount of operation of the control lever 27a flows to the hydraulic actuator 2. To adjust the position of the spool 21a. That is, the spool 21a is moved to a position corresponding to the differential pressure between the two pilot pressures piR and piL, and the differential pressure Δp between the two pilot pressures piR and piL is adjusted by adjusting the first output pressure psR. The spool 21a is moved to a position corresponding to the amount of operation of the control lever 27a, that is, toward the second offset position M2 by adjusting (the two-dot chain line in FIG. 3).
　例えば、油圧駆動システム１において、第２電磁比例制御弁２２Ｌが正常に動作する場合、操作レバー２７ａの操作量に対して第２電磁比例制御弁２２Ｌから圧力値ｐｘの出力圧ｐｓＬが出力されるとする。制御ユニット２６は、第２電磁比例制御弁２２Ｌが故障した場合も前述する操作量に対して同様のストローク量分だけスプール２１ａを移動させるべく、２つのパイロット圧ｐｉＬ，ｐｉＲの差圧（より詳細には、第２パイロット圧ｐｉＬから第１パイロット圧ｐｉＲを減算して得られる差圧）が圧力値ｐｘとなるように調整した出力圧ｐｓＲを第１電磁比例制御弁２２Ｒから出力させる。即ち、制御ユニット２６は、サブポンプ吐出圧ｐｐとの差分が圧力値ｐｘとなるように出力圧ｐｓＲを調整する。これにより、第２電磁比例制御弁２２Ｌが故障した場合でも、操作レバー２７ａの操作量に応じた速度で油圧アクチュエータ２を収縮させることができる。 For example, in the hydraulic drive system 1, when the second electromagnetic proportional control valve 22L operates normally, the output pressure psL of the pressure value px is output from the second electromagnetic proportional control valve 22L with respect to the operation amount of the control lever 27a. I assume. When the second electromagnetic proportional control valve 22L fails, the control unit 26 moves the spool 21a by the same stroke amount as the operation amount described above, so that the differential pressure between the two pilot pressures piL and piR (more detailed The output pressure psR adjusted so that the differential pressure obtained by subtracting the first pilot pressure piR from the second pilot pressure piL becomes the pressure value px is output from the first electromagnetic proportional control valve 22R. That is, the control unit 26 adjusts the output pressure psR so that the difference from the sub pump discharge pressure pp becomes the pressure value px. Thus, even when the second electromagnetic proportional control valve 22L fails, the hydraulic actuator 2 can be contracted at a speed according to the amount of operation of the control lever 27a.
　なお、図３の二点鎖線（前述する差分）からわかるように、第２電磁比例制御弁２２Ｌが通電不良になった場合において、操作レバー２７ａが第２方向Ａ２に操作される場合（即ち、ｐｓ２≦ｐｓＲ≦ｐｐ）、第１出力圧ｐｓＲとスプール２１ａの位置との関係が逆比例の関係を有している。即ち、制御ユニット２６が第１電磁比例制御弁２２Ｒに通電して開度を最も大きくた状態（即ち、第１出力圧ｐｓＲをサブポンプ吐出圧ｐｐと同圧になる状態）においてスプール２１ａが中立位置に位置する。また、その状態から制御ユニット２６が第１電磁比例制御弁２２Ｒに流す電流を小さくして前記開度を小さくすることによって、スプール２１ａの第２オフセット位置Ｍ２への方向のストローク量が増加し、第１出力圧ｐｓＲが第２所定圧力ｐｓ２と同圧となった際にストローク量が最大となる。 As can be seen from the two-dot chain line in FIG. 3 (the difference described above), when the second electromagnetic proportional control valve 22L fails to be energized, the operation lever 27a is operated in the second direction A2 (ie, The relationship between the first output pressure psR and the position of the spool 21a is in inverse proportion to each other. That is, the spool 21a is at the neutral position in a state where the control unit 26 energizes the first electromagnetic proportional control valve 22R and the opening degree is maximized (ie, the first output pressure psR becomes equal to the sub pump discharge pressure pp). Located in Further, from this state, the amount of stroke in the direction to the second offset position M2 of the spool 21a is increased by reducing the current supplied to the first electromagnetic proportional control valve 22R by the control unit 26 to reduce the opening degree, The stroke amount is maximized when the first output pressure psR becomes equal to the second predetermined pressure ps2.
　また、本実施形態の油圧駆動システム１は、前述する機能をあくまでフェールセーフ機能として備えているので、以下のように構成されている。即ち、本実施形態の油圧駆動システム１では、第２電磁比例制御弁２２Ｌが通電不良になった場合において、第２パイロット圧ｐｉＬを０≦ｐｉＬ≦ｐｐ－ｐｓ２の範囲で変動させることが可能である。それ故、サブポンプ吐出圧ｐｐから第２所定圧力ｐｓ２を減算した値が前述する圧力ｐｍ２より小さくなるように、サブポンプ吐出圧ｐｐ及び第２所定圧力ｐｓ２を設定する。これにより、第２電磁比例制御弁２２Ｌが故障した場合において、スプール２１ａの最大ストローク量を制限することができ、操作レバー２７ａの操作量が所定量を超えて操作された際に操作量に対する速度を比例せずに一定速に制限することができる。また、このようにすれば、部品を追加することなく、運転者に比例弁の故障を知らせることができる。なお、サブポンプ吐出圧ｐｐから第２所定圧力ｐｓ２を減算した値を圧力ｐｍ２より大きくしてもよい。その場合には故障時においても操作レバー２７ａの操作量に対して速度が制限されない油圧駆動システム１を構成することができる。 Moreover, since the hydraulic drive system 1 of this embodiment is provided with the function mentioned above as a fail safe function to the last, it is comprised as follows. That is, in the hydraulic drive system 1 according to the present embodiment, the second pilot pressure piL can be varied in the range of 0 ≦ piL ≦ pp−ps2 when the second electromagnetic proportional control valve 22L fails to be energized. is there. Therefore, the sub pump discharge pressure pp and the second predetermined pressure ps2 are set so that the value obtained by subtracting the second predetermined pressure ps2 from the sub pump discharge pressure pp becomes smaller than the above-described pressure pm2. Thereby, when the second electromagnetic proportional control valve 22L breaks down, the maximum stroke amount of the spool 21a can be limited, and the speed with respect to the operation amount when the operation amount of the operation lever 27a is operated beyond the predetermined amount Can be limited to constant speed without proportion. Also, in this way, the driver can be notified of the failure of the proportional valve without adding any parts. The value obtained by subtracting the second predetermined pressure ps2 from the sub pump discharge pressure pp may be larger than the pressure pm2. In that case, it is possible to configure the hydraulic drive system 1 whose speed is not limited with respect to the operation amount of the control lever 27a even at the time of failure.
　このように油圧駆動システム１では、第１電磁比例制御弁２２Ｒが故障していない正常な状態において出力しても有効に使われない第１規定圧力ｐｍ１以上の第１出力圧ｐｓＲを出力することによって、第２電磁比例制御弁２２Ｌにおける配線経路に故障が生じた場合にも第１電磁比例制御弁２２Ｒによって油圧アクチュエータ２を伸長させるだけでなく収縮させることを可能にしている。それ故、油圧駆動システム１では、第２電磁比例制御弁２２Ｌにおける配線経路に故障が生じた場合でもフェールセーフを達成することができ、信頼性の高い油圧駆動システム１を実現することができる。また、切換弁２４Ｒ，２４Ｌを追加するだけの構成であるので、フェールセーフを達成しつつ油圧駆動システム１のコスト増加を抑えることができる。 As described above, the hydraulic drive system 1 outputs the first output pressure psR at or above the first specified pressure pm1 that can not be effectively used even if the first electromagnetic proportional control valve 22R does not have a fault and outputs it in a normal state. Thus, even when a failure occurs in the wiring path in the second electromagnetic proportional control valve 22L, the first electromagnetic proportional control valve 22R enables the hydraulic actuator 2 to be contracted as well as extended. Therefore, in the hydraulic drive system 1, even when a failure occurs in the wiring path in the second electromagnetic proportional control valve 22L, failsafe can be achieved, and the highly reliable hydraulic drive system 1 can be realized. Moreover, since it is the structure which only adds switching valve 24R, 24L, the cost increase of the hydraulic drive system 1 can be suppressed, achieving fail safe.
　また、油圧駆動システム１では、第１規定圧力ｐｍ１を第２所定圧力ｐｓ２より小さく設定することによって、第２電磁比例制御弁２２Ｌが通電不良である状態において、第１パイロット圧ｐｉＲを第１規定圧力ｐｍ１まで昇圧してもサブポンプ吐出圧ｐｐが第２パイロット圧ｐｉＬとして出力されることがない。それ故、第２電磁比例制御弁２２Ｌが通電不良である状態においても、スプール２１ａを第１オフセット位置Ｍ１に向かって最大ストローク量までストロークさせることができる。即ち、第２電磁比例制御弁２２Ｌが通電不良である状態において、スプール２１ａを第１オフセット位置Ｍ１に移動させる際に油圧駆動装置１４の機能が低下することを抑えることができる。 Further, in the hydraulic drive system 1, by setting the first prescribed pressure pm1 to be smaller than the second prescribed pressure ps2, the first pilot pressure piR is prescribed first in a state where energization of the second electromagnetic proportional control valve 22L is defective. Even if the pressure is increased to the pressure pm1, the sub pump discharge pressure pp is not output as the second pilot pressure piL. Therefore, even in the state where the second electromagnetic proportional control valve 22L is in the state of the electrification failure, the spool 21a can be made to stroke toward the first offset position M1 up to the maximum stroke amount. That is, in the state where the second electromagnetic proportional control valve 22L is in the state of energization failure, it is possible to suppress the decrease in the function of the hydraulic drive device 14 when moving the spool 21a to the first offset position M1.
　次に、第２電磁比例制御弁２２Ｌの第２出力圧ｐｓＬ（又は第１電磁比例制御弁２２Ｒの第１出力圧ｐｓＲ）がゼロに維持されるような故障として、その出力側とタンク１２とが連通した状態のままで第２電磁比例制御弁２２Ｌ（又は第１電磁比例制御弁２２Ｒ）の弁体がスティックする場合について説明する。この場合もまた、前述するような第２電磁比例制御弁２２Ｌに対して通電ができない場合と同じ制御を実行することによって、操作レバー２７ａの操作量に応じて油圧アクチュエータ２を収縮させることができる。なお、第１電磁比例制御弁２２Ｒ及び第２電磁比例制御弁２２Ｌがその出力側とタンク１２とが連通した状態のまま弁体がスティックしているか否かは、第１電磁比例制御弁２２Ｒ及び第２電磁比例制御弁２２Ｌに対する通電状態を検知しつつ、操作レバー２７ａの操作量とメインポンプ１１の吐出圧ｐとの関係から検知することができる。 Next, the second output pressure psL of the second electromagnetic proportional control valve 22L (or the first output pressure psR of the first electromagnetic proportional control valve 22R) is maintained at zero as a fault such that the output side and the tank 12 A case where the valve body of the second electromagnetic proportional control valve 22L (or the first electromagnetic proportional control valve 22R) sticks with the second valve 31 communicating with each other will be described. Also in this case, the hydraulic actuator 2 can be contracted according to the amount of operation of the control lever 27a by executing the same control as when the second electromagnetic proportional control valve 22L can not be energized as described above. . It should be noted that whether or not the valve body sticks while the first electromagnetic proportional control valve 22R and the second electromagnetic proportional control valve 22L are in communication with the output side thereof is the first electromagnetic proportional control valve 22R and It is possible to detect from the relationship between the operation amount of the control lever 27a and the discharge pressure p of the main pump 11 while detecting the energization state of the second electromagnetic proportional control valve 22L.
　最後に、油圧駆動システム１において、第１電磁比例制御弁２２Ｒ及び第２電磁比例制御弁２２Ｌの何れか一方の弁体が、その出力側とサブ通路２０とを連通させた状態のままスティックした場合について説明する。なお、第１電磁比例制御弁２２Ｒ及び第２電磁比例制御弁２２Ｌの何れがスティックした場合であっても、スティックしていない他方によってフェールセーフを達成することができる。それ故、配線経路の故障に関する説明と同様、第２電磁比例制御弁２２Ｌの弁体がその出力側とサブ通路２０とを連通させた状態のままでスティックした場合についてのみ説明する。 Finally, in the hydraulic drive system 1, the valve body of one of the first electromagnetic proportional control valve 22R and the second electromagnetic proportional control valve 22L is stuck in a state in which the output side thereof communicates with the sub passage 20 The case will be described. Note that even if either of the first electromagnetic proportional control valve 22R and the second electromagnetic proportional control valve 22L is stuck, fail safe can be achieved by the other one not sticking. Therefore, as in the description regarding the failure of the wiring path, only the case where the valve body of the second electromagnetic proportional control valve 22L sticks with the output side thereof communicated with the sub passage 20 will be described.
　第２電磁比例制御弁２２Ｌでは、その出力側とその一次圧を与えるサブ通路２０とを連通させた状態で弁体がスティックすると、第２電磁比例制御弁２２Ｌの第２出力圧ｐｓＬがサブポンプ吐出圧ｐｐと等しくなる。そのため、第２切換弁２４Ｌのスプール２４Ｌａは、第１パイロット圧ｐｉＲの大きさに関係なく第１位置Ｍ１Ｌに位置し、サブポンプ吐出圧ｐｐに等しい第２出力圧ｐｓＬが第２パイロット圧ｐｉＬとして流量制御弁２１に出力される。他方、第１切換弁２４Ｒのスプール２４Ｒａは、第１電磁比例制御弁２２Ｒに通電されていない状態でサブポンプ吐出圧ｐｐに等しい第２出力圧ｐｓＬが第２パイロット圧ｐｉＬとして出力されることによって第２位置Ｍ２Ｒに移動する。これにより、第１パイロット圧ｐｉＲとしてサブポンプ吐出圧ｐｐが流量制御弁２１に出力される。そうすることで、流量制御弁２１のスプール２１ａに同圧の第１パイロット圧ｐｉＲ及び第２パイロット圧ｐｉＬが互いに抗するように作用し、スプール２１ａが中立位置Ｍ０に保持される。その結果、作動油が油圧アクチュエータ２に導かれて不所望な動きをすることを防ぐことができ、フェールセーフを達成することができる。 In the second electromagnetic proportional control valve 22L, when the valve stick sticks in a state in which the output side and the sub passage 20 for providing the primary pressure are communicated, the second output pressure psL of the second electromagnetic proportional control valve 22L is the sub pump discharge It becomes equal to the pressure pp. Therefore, the spool 24La of the second switching valve 24L is located at the first position M1L regardless of the magnitude of the first pilot pressure piR, and the second output pressure psL equal to the sub pump discharge pressure pp is the flow rate as the second pilot pressure piL. It is output to the control valve 21. On the other hand, when the spool 24Ra of the first switching valve 24R is not energized to the first electromagnetic proportional control valve 22R, the second output pressure psL equal to the sub pump discharge pressure pp is output as the second pilot pressure piL. Move to 2 position M2R. As a result, the sub pump discharge pressure pp is output to the flow control valve 21 as the first pilot pressure piR. By doing so, the first pilot pressure piR and the second pilot pressure piL of the same pressure act on the spool 21a of the flow control valve 21 to oppose each other, and the spool 21a is held at the neutral position M0. As a result, hydraulic fluid can be prevented from being guided to the hydraulic actuator 2 to perform an undesired movement, and fail safe can be achieved.
　［その他の実施形態］
　本実施形態の油圧駆動システム１は、１つの油圧アクチュエータ２にしか接続されていないが、前述の通り接続される油圧アクチュエータは１つに限定されない。例えば、油圧駆動システム１が２つ以上の油圧アクチュエータに接続されていてもよく、それに応じて複数の流量制御弁２１を有していてもよい。この場合、複数の流量制御弁２１は、例えばメインポンプ１１に対して並列して接続され、流量制御弁２１の各々に対して第１電磁比例制御弁２２Ｒ、第２電磁比例制御弁２２Ｌ、第１切換弁２４Ｒ、及び第２切換弁２４Ｌが夫々設けられている。これにより、複数の流量制御弁２１を備える油圧駆動システムもまた前述する場合と同様の機能を達成する。また、油圧駆動システム１では、流量制御弁２１の何れのポート２１Ｒ，２１Ｌにも切換弁２４Ｒ，２４Ｌが設けられているが、必ずしも両方設けられている必要はなく何れか一方だけであってもよい。 Other Embodiments
Although the hydraulic drive system 1 of this embodiment is connected to only one hydraulic actuator 2, the hydraulic actuator connected as described above is not limited to one. For example, the hydraulic drive system 1 may be connected to two or more hydraulic actuators, and may have a plurality of flow control valves 21 accordingly. In this case, the plurality of flow control valves 21 are connected, for example, in parallel to the main pump 11, and each of the flow control valves 21 is provided with a first electromagnetic proportional control valve 22R, a second electromagnetic proportional control valve 22L, A first switching valve 24R and a second switching valve 24L are provided respectively. Thereby, the hydraulic drive system provided with the plurality of flow control valves 21 also achieves the same function as the case described above. Further, in the hydraulic drive system 1, the switch valves 24R and 24L are provided at any of the ports 21R and 21L of the flow control valve 21. However, it is not necessary to have both of them. Good.
　また、本実施形態の油圧駆動システム１では、一定の設定圧を供給する圧力源がサブポンプ１３及びリリーフ弁２８によって構成されているが、必ずしもこのような構成である必要なない。例えば、メインポンプ１１及び減圧弁によって圧力源を構成し、メインポンプ１１と流量制御弁２１とを繋ぐメイン通路から減圧弁を介してサブ通路２０に一定の設定圧を供給するようにしてもよい。 Further, in the hydraulic drive system 1 of the present embodiment, the pressure source for supplying a constant set pressure is configured by the sub pump 13 and the relief valve 28, but such a configuration is not necessarily required. For example, a pressure source may be configured by the main pump 11 and the pressure reducing valve, and a predetermined set pressure may be supplied to the sub passage 20 from the main passage connecting the main pump 11 and the flow control valve 21 via the pressure reducing valve. .
　更に、本実施形態の油圧駆動システム１では、電磁比例制御弁２２Ｒ，２２Ｌにおける故障が発生した後において油圧アクチュエータ２の最大速度を制限し、故障発生前後における操作レバー２７ａの操作量と油圧アクチュエータ２の速度との関係が変化しないように制御ユニット２６が構成されている。しかし、制御ユニット２６は、必ずしもこのように構成されている必要はない。即ち、故障発生後においても操作レバー２７ａの操作量を最大にすると、故障発生前と同様の最大速度にて油圧アクチュエータ２が駆動できるように操作レバー２７ａの操作量と油圧アクチュエータ２の速度との対応関係を変えるようにしてもよい。この場合、サブポンプ吐出圧ｐｐは、第１所定圧力ｐｓ１に第２規定圧力ｐｍ２を加算した圧力，第２所定圧力ｐｓ２に第１規定圧力ｐｍ１を加算した圧力の高い方とする必要がある。 Furthermore, in the hydraulic drive system 1 of the present embodiment, the maximum speed of the hydraulic actuator 2 is limited after occurrence of a failure in the electromagnetic proportional control valves 22R and 22L, and the operation amount of the control lever 27a before and after the failure occurrence and the hydraulic actuator 2 The control unit 26 is configured such that the relationship with the speed of the vehicle does not change. However, the control unit 26 does not necessarily have to be configured in this way. That is, when the operation amount of the operation lever 27a is maximized even after the failure occurs, the operation amount of the operation lever 27a and the speed of the hydraulic actuator 2 are set so that the hydraulic actuator 2 can be driven at the same maximum speed as before the failure occurrence. The correspondence relationship may be changed. In this case, the sub pump discharge pressure pp needs to be a pressure obtained by adding the second predetermined pressure pm2 to the first predetermined pressure ps1, and a pressure obtained by adding the first predetermined pressure pm1 to the second predetermined pressure ps2.
　更に、本実施形態の油圧駆動システム１では、油圧アクチュエータ２として油圧シリンダが採用されているが、必ずしも油圧シリンダに限定されない。即ち、油圧アクチュエータ２は、油圧モータであってもよく、作動油などの作動油を供給することによって作動するものであればよい。 Furthermore, in the hydraulic drive system 1 of the present embodiment, a hydraulic cylinder is employed as the hydraulic actuator 2, but the present invention is not necessarily limited to the hydraulic cylinder. That is, the hydraulic actuator 2 may be a hydraulic motor, as long as it operates by supplying hydraulic fluid such as hydraulic fluid.
　１　油圧駆動システム
　２　油圧アクチュエータ
　１１　メインポンプ
　１３　サブポンプ
　１４　油圧駆動装置
　２１　流量制御弁
　２１ａ　スプール
　２１Ｒ　第１パイロットポート
　２１Ｌ　第２パイロットポート
　２２Ｒ　第１電磁比例制御弁
　２２Ｌ　第２電磁比例制御弁
　２３Ｒ　第１パイロット通路
　２３Ｌ　第２パイロット通路
　２４Ｒ　第１切換弁
　２４Ｌ　第２切換弁
　２５Ｒ　第１油通路
　２５Ｌ　第２油通路
　２６　制御ユニット
　２７　操作装置 DESCRIPTION OF SYMBOLS 1 hydraulic drive system 2 hydraulic actuator 11 main pump 13 sub pump 14 hydraulic drive 21 flow control valve 21a spool 21R 1st pilot port 21L 2nd pilot port 22R 1st electromagnetic proportional control valve 22L 2nd electromagnetic proportional control valve 23R 1st pilot Passage 23L Second pilot passage 24R First switching valve 24L Second switching valve 25R First oil passage 25L Second oil passage 26 Control unit 27 Operating device

Claims (6)

  1. 　互いに抗する方向に２つのパイロット圧が入力され、前記２つのパイロット圧の差圧に応じて所定方向一方及び他方に夫々移動してメインポンプから油圧アクチュエータに流れる作動油の方向を切換えると共に前記メインポンプと油圧アクチュエータとの間の開度を制御するスプールを有する流量制御弁と、
    　一定の設定圧に保たれた圧油を供給する圧力源から供給される圧油を一次圧とする正比例型の電磁比例制御弁であって、入力される電流に応じた第１出力圧に減圧制御し、前記第１出力圧を前記２つのパイロット圧のうちの一方である第１パイロット圧として前記流量制御弁に出力して前記スプールを前記所定方向一方に移動させる正比例型の第１電磁比例制御弁と、
    　前記圧力源から供給される圧油を一次圧とする正比例型の電磁比例制御弁であって、入力される電流に応じて、第２出力圧に減圧制御して出力する正比例型の第２電磁比例制御弁と、
    　前記圧力源から供給される設定圧及び前記第２電磁比例制御弁から出力される前記第２出力圧のうち何れかを前記２つのパイロット圧のうちの他方である第２パイロット圧として前記流量制御弁に出力して前記スプールを前記所定方向他方に移動させる切換弁と、
    　前記第１電磁比例制御弁と前記流量制御弁との間の通路から分岐して前記切換弁に接続する油通路と、
    　互いに異なる第１方向及び第２方向に操作可能な操作装置と、
    　前記第１電磁比例制御弁及び前記第２電磁比例制御弁が正常に作動する状態で、且つ前記操作装置が前記第１方向に操作される場合は、その第１方向操作量に応じた電流を前記第１電磁比例制御弁に流し、前記操作装置が前記第２方向に操作される場合は、その第２方向操作量に応じた電流を前記第２電磁比例制御弁に流す制御ユニットと、を備え、
    　前記切換弁には前記第１パイロット圧と前記第２出力圧とが互いに抗するように入力され、前記切換弁は、前記第１パイロット圧から前記第２出力圧を差し引いた差分が予め定められた所定圧力以上である場合は、前記設定圧を第２パイロット圧として前記流量制御弁に出力し、前記差分が前記所定圧力未満である場合は、前記第２出力圧を前記第２パイロット圧として出力し、
    　前記制御ユニットは、前記操作装置が前記第２方向に操作されても前記第２出力圧がゼロに維持されるような故障が前記第２電磁比例制御弁又はその配線経路に生じていると判断した場合は、前記第１電磁比例制御弁に通電して前記所定圧力以上で且つ前記操作装置の第２方向操作量に応じた前記第１出力圧を前記第１パイロット圧として前記第１電磁比例制御弁から前記流量制御弁及び前記切換弁に出力させる、油圧駆動装置。     Two pilot pressures are input in directions opposite to each other, and are respectively moved in one direction and the other in a predetermined direction according to the differential pressure of the two pilot pressures to switch the direction of hydraulic fluid flowing from the main pump to the hydraulic actuator and A flow control valve having a spool for controlling the opening between the pump and the hydraulic actuator;
    A direct proportional electromagnetic proportional control valve that uses pressure oil supplied from a pressure source that supplies pressure oil maintained at a constant set pressure as the primary pressure, and reduces the pressure to the first output pressure according to the input current A direct proportional type first electromagnetic proportional control for controlling and outputting the first output pressure to the flow control valve as the first pilot pressure which is one of the two pilot pressures to move the spool in one of the predetermined directions Control valve,
    A direct proportional electromagnetic proportional control valve, wherein the pressure oil supplied from the pressure source is used as a primary pressure, wherein the second proportional proportional electromagnetic valve is controlled to reduce the pressure to a second output pressure according to the input current. Proportional control valve,
    Either the set pressure supplied from the pressure source or the second output pressure output from the second electromagnetic proportional control valve is used as the second pilot pressure which is the other of the two pilot pressures, the flow rate control A switching valve that outputs to the valve to move the spool to the other in the predetermined direction;
    An oil passage branched from a passage between the first electromagnetic proportional control valve and the flow control valve and connected to the switching valve;
    An operating device operable in different first and second directions;
    When the first electromagnetic proportional control valve and the second electromagnetic proportional control valve operate normally, and the operating device is operated in the first direction, the current corresponding to the first direction operation amount is A control unit that causes the first electromagnetic proportional control valve to flow, and when the operating device is operated in the second direction, causes a current corresponding to the second directional operation amount to flow to the second electromagnetic proportional control valve; Equipped
    The first pilot pressure and the second output pressure are input to the switching valve so as to be opposed to each other, and the switching valve has a predetermined difference obtained by subtracting the second output pressure from the first pilot pressure. When the pressure is higher than the predetermined pressure, the set pressure is output as the second pilot pressure to the flow control valve, and when the difference is less than the predetermined pressure, the second output pressure is set as the second pilot pressure. Output
    The control unit determines that a failure has occurred in the second electromagnetic proportional control valve or its wiring path such that the second output pressure is maintained at zero even if the operating device is operated in the second direction. In the case where the first electromagnetic proportional control valve is energized, the first output pressure according to the second direction operation amount of the operating device is equal to or higher than the predetermined pressure and the first A hydraulic drive system for causing the control valve to output the flow control valve and the switching valve.
  2. 　前記スプールは、前記第２パイロット圧に比べて前記第１パイロット圧が大きく且つ前記２つのパイロット圧の差圧が予め定められる規定圧力に達すると、前記所定方向一方へのストローク量が最大となるように構成され、
    　前記切換弁は、前記所定圧力が前記規定圧力より大きくなるように構成されている、請求項１に記載の油圧駆動装置。     When the first pilot pressure is greater than the second pilot pressure and the differential pressure between the two pilot pressures reaches a predetermined pressure, the stroke amount in one of the predetermined directions is maximized. Configured as
    The hydraulic drive system according to claim 1, wherein the switching valve is configured such that the predetermined pressure is higher than the predetermined pressure.
  3. 　前記第１電磁比例制御弁から出力される前記第１出力圧及び前記圧力源によって一定に保たれている設定圧のうち何れか一方を前記第１パイロット圧として前記流量制御弁に出力する第１切換弁、を更に備え、
    　前記第１切換弁には前記第２パイロット圧と前記第１出力圧とが互いに抗するように入力され、前記第１切換弁は、前記第２パイロット圧から前記第１出力圧を差し引いた第１差分が第１所定圧力以上である場合は、前記設定圧を前記第１パイロット圧として出力し、前記第１差分が前記第１所定圧力未満である場合は、前記第１出力圧を前記第１パイロット圧として出力し、
    　前記切換弁である第２切換弁には前記第１パイロット圧と前記第２出力圧とが互いに抗するように入力され、前記第２切換弁は、前記第１パイロット圧から前記第２出力圧を差し引いた差分である第２差分が所定圧力である第２所定圧力以上である場合は、前記設定圧を前記第２パイロット圧として前記流量制御弁に出力し、前記第２差分が前記第２所定圧力未満である場合は、前記第２出力圧を前記第２パイロット圧として前記流量制御弁に出力し、
    　前記制御ユニットは、前記操作装置が前記第１方向に操作されても前記第１出力圧がゼロに維持されるような故障が前記第１電磁比例制御弁又はその配線経路に生じていると判断した場合は、前記第２電磁比例制御弁に通電して前記第１所定圧力以上で且つ前記操作装置の第１方向操作量に応じた前記第２出力圧を前記第２パイロット圧として前記第２電磁比例制御弁から前記流量制御弁及び前記第２切換弁に出力させる、請求項１に記載の油圧駆動装置。     A first one of the first output pressure output from the first electromagnetic proportional control valve and a set pressure maintained constant by the pressure source is output to the flow control valve as the first pilot pressure. Further comprising a switching valve;
    The second pilot pressure and the first output pressure are input to the first switching valve so as to oppose each other, and the first switching valve is configured by subtracting the first output pressure from the second pilot pressure. When the one difference is equal to or more than a first predetermined pressure, the set pressure is output as the first pilot pressure, and when the first difference is less than the first predetermined pressure, the first output pressure is output as the first pressure. Output as 1 pilot pressure,
    The first pilot pressure and the second output pressure are input to the second switching valve, which is the switching valve, so as to oppose each other, and the second switching valve is configured to generate the second output pressure from the first pilot pressure. When the second difference which is the difference obtained by subtracting is equal to or more than the second predetermined pressure which is the predetermined pressure, the set pressure is outputted to the flow control valve as the second pilot pressure, and the second difference is the second When the pressure is less than the predetermined pressure, the second output pressure is output to the flow control valve as the second pilot pressure,
    The control unit determines that a failure has occurred in the first electromagnetic proportional control valve or its wiring path such that the first output pressure is maintained at zero even if the operating device is operated in the first direction. In this case, the second output pressure corresponding to the first direction operation amount of the operating device is equal to or higher than the first predetermined pressure by energizing the second electromagnetic proportional control valve and the second pilot pressure is used as the second pilot pressure. The hydraulic drive according to claim 1, wherein the flow control valve and the second switching valve are output from an electromagnetic proportional control valve.
  4. 　前記スプールは、前記第２パイロット圧に比べて前記第１パイロット圧が大きく且つ前記２つのパイロット圧の差圧が予め定められた第１規定圧力に達すると前記所定方向一方へのストローク量が最大となり、前記第１パイロット圧に比べて前記第２パイロット圧が大きく且つ前記２つのパイロット圧の差圧が予め定められる第２規定圧力に達すると、前記所定方向他方へのストローク量が最大となるように構成され、
    　前記第１切換弁は、前記第１所定圧力が前記第１規定圧力より大きくなるように構成され、
    　前記第２切換弁は、前記第２所定圧力が前記第２規定圧力より大きくなるように構成されている、請求項３に記載の油圧駆動装置。     The spool has a maximum stroke amount in one of the predetermined directions when the first pilot pressure is larger than the second pilot pressure and the differential pressure between the two pilot pressures reaches a predetermined first prescribed pressure. When the second pilot pressure is greater than the first pilot pressure and the differential pressure between the two pilot pressures reaches a predetermined second predetermined pressure, the stroke amount in the other of the predetermined directions is maximized. Configured as
    The first switching valve is configured such that the first predetermined pressure is greater than the first predetermined pressure,
    The hydraulic drive system according to claim 3, wherein the second switching valve is configured such that the second predetermined pressure is larger than the second predetermined pressure.
  5. 　前記スプールは、前記２つのパイロット圧の差圧がゼロの場合において、前記メインポンプと前記油圧アクチュエータとの間を遮断する中立位置に位置する、請求項１乃至４の何れか１つに記載の油圧駆動装置。 The said spool is located in the neutral position which interrupts | blocks between the said main pump and the said hydraulic actuator, when the differential pressure | voltage of two said pilot pressure is zero. Hydraulic drive.
  6. 　請求項１乃至５の何れか１つに記載の油圧駆動装置と、
    　前記油圧アクチュエータに供給する作動油を吐出する前記メインポンプと、
    　前記圧力源を構成するサブポンプと、を備える油圧駆動システム。     A hydraulic drive system according to any one of claims 1 to 5,
    The main pump that discharges hydraulic oil supplied to the hydraulic actuator;
    And a sub pump constituting the pressure source.
PCT/JP2018/026663 2017-07-21 2018-07-17 Hydraulic drive device and hydraulic drive system provided therewith WO2019017318A1 (en)

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JP7500297B2 (en) 2020-06-16 2024-06-17 住友建機株式会社 Excavator

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JP2017110672A (en) * 2015-12-14 2017-06-22 川崎重工業株式会社 Hydraulic drive system

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JPH0719207A (en) * 1993-07-02 1995-01-20 Hitachi Constr Mach Co Ltd Driving controller of hydraulic machinery
JP2017110672A (en) * 2015-12-14 2017-06-22 川崎重工業株式会社 Hydraulic drive system

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Publication number Priority date Publication date Assignee Title
WO2020158542A1 (en) * 2019-01-31 2020-08-06 日立建機株式会社 Work machine
JP2020122337A (en) * 2019-01-31 2020-08-13 日立建機株式会社 Work machine
CN112639220A (en) * 2019-01-31 2021-04-09 日立建机株式会社 Working machine
CN112639220B (en) * 2019-01-31 2022-07-01 日立建机株式会社 Working machine
JP7123821B2 (en) 2019-01-31 2022-08-23 日立建機株式会社 working machine

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