WO2016006454A1 - 液圧駆動システム - Google Patents
液圧駆動システム Download PDFInfo
- Publication number
- WO2016006454A1 WO2016006454A1 PCT/JP2015/068235 JP2015068235W WO2016006454A1 WO 2016006454 A1 WO2016006454 A1 WO 2016006454A1 JP 2015068235 W JP2015068235 W JP 2015068235W WO 2016006454 A1 WO2016006454 A1 WO 2016006454A1
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- WIPO (PCT)
- Prior art keywords
- pressure
- command
- hydraulic
- control unit
- pump
- Prior art date
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/44—Control of exclusively fluid gearing hydrostatic with more than one pump or motor in operation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K17/00—Arrangement or mounting of transmissions in vehicles
- B60K17/04—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing
- B60K17/10—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing of fluid gearing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K7/00—Disposition of motor in, or adjacent to, traction wheel
- B60K7/0015—Disposition of motor in, or adjacent to, traction wheel the motor being hydraulic
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D11/00—Steering non-deflectable wheels; Steering endless tracks or the like
- B62D11/001—Steering non-deflectable wheels; Steering endless tracks or the like control systems
- B62D11/005—Hydraulic control systems
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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
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
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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
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/027—Check valves
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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
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/06—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with two or more servomotors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H39/00—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution
- F16H39/02—Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution with liquid motors at a distance from liquid pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/4008—Control of circuit pressure
- F16H61/4017—Control of high pressure, e.g. avoiding excess pressure by a relief valve
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/4061—Control related to directional control valves, e.g. change-over valves, for crossing the feeding conduits
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/46—Automatic regulation in accordance with output requirements
- F16H61/478—Automatic regulation in accordance with output requirements for preventing overload, e.g. high pressure limitation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D11/00—Steering non-deflectable wheels; Steering endless tracks or the like
- B62D11/02—Steering non-deflectable wheels; Steering endless tracks or the like by differentially driving ground-engaging elements on opposite vehicle sides
- B62D11/04—Steering non-deflectable wheels; Steering endless tracks or the like by differentially driving ground-engaging elements on opposite vehicle sides by means of separate power sources
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/205—Systems with pumps
- F15B2211/20576—Systems with pumps with multiple pumps
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/25—Pressure control functions
Definitions
- the present invention relates to a hydraulic drive system that transmits power by hydraulic pressure.
- a hydraulic drive system for example, a hydraulic drive system as disclosed in JP2003-63266A is known.
- JP 2003-63266A discloses a two-pump, two-motor hydraulic drive system including two HSTs on the left and right sides of a variable displacement hydraulic pump and a variable displacement hydraulic motor fluidly connected in a closed circuit.
- An object of the present invention is to provide a hydraulic drive system capable of suppressing a load applied to a drive source.
- a hydraulic drive system the first hydraulic pump and the second hydraulic pump that are driven by the power of the drive source and are capable of changing the discharge capacity and the discharge direction of the hydraulic fluid,
- a first hydraulic motor that is driven by hydraulic fluid discharged from the first hydraulic pump and transmits power to one of the left and right drive wheels, and a right and left driven by hydraulic fluid discharged from the second hydraulic pump
- a second hydraulic motor that transmits power to the other of the drive wheels
- a first hydraulic pressure pump that controls a discharge capacity and a discharge direction of the first hydraulic pump according to a first command pressure generated in response to an operation by an operator.
- a first pump control unit a second pump control unit that controls a discharge capacity and a discharge direction of the second hydraulic pump in accordance with a second command pressure generated in response to an operation by an operator, and the first hydraulic pressure.
- the signal pressure generation unit that generates the signal pressure for adjusting the first command pressure and the second command pressure, and the first command pressure according to the signal pressure generated by the signal pressure generation unit
- a second pressure adjusting unit that adjusts the second command pressure in accordance with the signal pressure generated by the signal pressure generating unit.
- FIG. 1 is a hydraulic circuit diagram of a hydraulic drive system according to the first embodiment of the present invention.
- FIG. 2 is a hydraulic circuit diagram of the hydraulic drive system according to the second embodiment of the present invention.
- FIG. 3 is a hydraulic circuit diagram of a hydraulic drive system according to a comparative example of the present invention.
- the hydraulic drive system circulates hydraulic fluid between a hydraulic pump and a hydraulic motor to transmit power, and a hydrostatic transmission device (Hydro) that continuously controls the speed ratio of the hydraulic motor to the hydraulic pump.
- HST Hydrostatic Transmission
- the hydraulic drive system is mounted on a work vehicle such as a forklift.
- the hydraulic drive system controls the running of the vehicle by controlling the power transmitted from the drive source to the left and right drive wheels (tires, crawlers, etc.).
- hydraulic drive systems 100 and 200 in which hydraulic oil is used as the hydraulic fluid will be described.
- the hydraulic fluid is not limited to hydraulic oil, and may be other liquid such as a water-soluble alternative liquid.
- the hydraulic drive system 100 is driven by the power of an engine 4 as a drive source that is transmitted via a common drive shaft 1 and can change the discharge capacity and discharge direction of hydraulic oil.
- the first hydraulic pump 11 as a pressure pump
- the second hydraulic pump 21 as a second hydraulic pump
- the left drive of the left and right drive wheels 2 and 3 driven by hydraulic oil discharged from the first hydraulic pump 11
- a first hydraulic motor 12 serving as a first hydraulic motor that transmits power to the wheel 2 and a right driving wheel 3 among right and left driving wheels 2 and 3 driven by hydraulic oil discharged from the second hydraulic pump 21.
- the first hydraulic pump 11 and the second hydraulic pump 21 are variable displacement swash plate type piston pumps each having a pair of supply / discharge ports 11A and 11B and a pair of supply / discharge ports 21A and 21B.
- the first hydraulic pump 11 sucks hydraulic oil from one of the pair of supply / discharge ports 11A and 11B and discharges hydraulic oil from the other.
- the second hydraulic pump 21 sucks hydraulic oil from one of the pair of supply / discharge ports 21A and 21B and discharges hydraulic oil from the other. That is, the first hydraulic pump 11 and the second hydraulic pump 21 each have two discharge directions.
- the swash plates of the first hydraulic pump 11 and the second hydraulic pump 21 are provided so as to be tiltable in the forward direction and the reverse direction from the neutral position, respectively.
- the first hydraulic pump 11 and the second hydraulic pump 21 discharge hydraulic oil with a discharge capacity and a discharge direction corresponding to the angle of the swash plate, respectively.
- the discharge directions of the first hydraulic pump 11 and the second hydraulic pump 21 are controlled according to the respective swash plate angles.
- the first hydraulic motor 12 and the second hydraulic motor 22 are connected to the first hydraulic pump 11 and the second hydraulic pump 21 by a closed circuit, respectively.
- the first hydraulic motor 12 has a drive shaft 12 ⁇ / b> A connected to the left drive wheel 2.
- the first hydraulic motor 12 is driven by hydraulic oil supplied from the first hydraulic pump 11, thereby transmitting the power of the engine 4 to the left drive wheel 2.
- the second hydraulic motor 22 has a drive shaft 22 ⁇ / b> A connected to the right drive wheel 3.
- the second hydraulic motor 22 is driven by the hydraulic oil supplied from the second hydraulic pump 21 to transmit the power of the engine 4 to the right drive wheel 3.
- the first hydraulic motor 12 and the second hydraulic motor 22 transmit the power of the engine 4 to different drive wheels of the left and right drive wheels 2 and 3, respectively.
- the first pump control unit 13 and the second pump control unit 23 are servo regulators that change the swash plate tilt angles of the first hydraulic pump 11 and the second hydraulic pump 21 according to the input pressure.
- the first pump control unit 13 is provided with a first forward rotation port 13A and a first reverse rotation port 13B.
- the second pump control unit 23 is provided with a second forward rotation port 23A and a second reverse rotation port 23B.
- the first pump control unit 13 and the second pump control unit 23 are connected to the first hydraulic pump 11 and the hydraulic pump according to the pressure of the hydraulic oil.
- the swash plate of the second hydraulic pump 21 is tilted in the forward direction. Thereby, the discharge directions of the first hydraulic pump 11 and the second hydraulic pump 21 are controlled to one of the two discharge directions.
- the first pump control unit 13 and the second pump control unit 23 correspond to the first hydraulic pump 11 and the second hydraulic pump according to the pressure of the hydraulic oil. 2
- the swash plate of the hydraulic pump 21 is tilted in the opposite direction. Thereby, the discharge directions of the first hydraulic pump 11 and the second hydraulic pump 21 are controlled to the other of the two discharge directions.
- the first pump control unit 13 and the second pump control unit 23 are configured to tilt the swash plate of the first hydraulic pump 11 and the second hydraulic pump 21 according to the port through which the hydraulic oil is guided, that is, the discharge direction. To control each. Further, the first pump control unit 13 and the second pump control unit 23 are arranged to tilt the swash plates of the first hydraulic pump 11 and the second hydraulic pump 21 according to the pressure of the hydraulic oil guided to the port, that is, the discharge capacity. To control each.
- the first hydraulic pump 11, the first hydraulic motor 12, and the first pump control unit 13 form one HST (hereinafter referred to as “first power transmission unit 10”). Composed.
- the second hydraulic pump 21, the second hydraulic motor 22, and the second pump control unit 23 constitute one HST (hereinafter referred to as “second power transmission unit 20”). That is, the hydraulic drive system 100 is a two-pump two-motor type hydraulic drive system including a pair of hydraulic pumps and hydraulic motors, and the left and right drive wheels 2 and 3 are respectively connected to the first power transmission unit 10 and the second power transmission unit. 20 independently controlled.
- the hydraulic drive system 100 includes first command pressures P1 and P2 and second command pressures P3 and P4 for commanding the first pump control unit 13 and the second pump control unit 23, respectively, according to an input operation.
- the first command pressures P1, P2 and the second command pressures P3, P4 are adjusted in accordance with the sum of the discharge pressures of the hydraulic fluid discharged from the operation unit 30 that generates the hydraulic pressure and the first hydraulic pump 11 and the second hydraulic pump 21.
- the signal pressure generating unit 40 that generates the signal pressure PS for the control and the first command pressures P1 and P2 for instructing the first pump control unit 13 to control the signal pressure PS generated by the signal pressure generating unit 40
- the first pressure adjusting unit 50 that adjusts accordingly and the second command pressures P3 and P4 for commanding the second pump control unit 23 to control are adjusted according to the signal pressure PS generated by the signal pressure generating unit 40.
- the operation unit 30 includes, for example, a joystick 31 provided in a driver's seat and operated by an operator.
- the operation unit 30 includes two first command pressures P1 and P2 for controlling the left drive wheel 2 and the right drive wheel 3 in accordance with an operation input from the joystick 31 such as going straight or turning. And generate and output two second command pressures P3 and P4.
- the operation unit 30 is not limited to the joystick 31 and may be input from, for example, a handle.
- the signal pressure generator 40 is provided between the first hydraulic pump 11 and the first hydraulic motor 12, and a first discharge pressure selection valve 41 that selects a high pressure side of the hydraulic oil supplied to and discharged from the first hydraulic pump 11.
- a second discharge pressure selection valve 42 that is provided between the second hydraulic pump 21 and the second hydraulic motor 22 and selects the high pressure side of the hydraulic oil supplied to and discharged from the second hydraulic pump 21; and the drive shaft 1 It is driven by the power of the engine 4 transmitted through the pilot pump 43 that draws hydraulic oil from a tank (not shown) and generates the signal source pressure PP, and is discharged from the first hydraulic pump 11 and the second hydraulic pump 21.
- a signal pressure adjusting valve 44 that adjusts the signal source pressure PP according to the sum of the discharge pressures of the respective hydraulic oils to generate the signal pressure PS.
- the first discharge pressure selection valve 41 and the second discharge pressure selection valve 42 are shuttles that select a high-pressure side through a part of the hydraulic fluid supplied to and discharged from each of the first hydraulic pump 11 and the second hydraulic pump 21. It is a valve.
- the hydraulic oil on the high pressure side selected by the first discharge pressure selection valve 41 and the second discharge pressure selection valve 42, that is, a part of the hydraulic oil discharged from the first hydraulic pump 11 and the second hydraulic pump 21, respectively is a pilot.
- the pressure is led to the signal pressure adjusting valve 44.
- the signal pressure adjusting valve 44 is a pressure reducing valve that adjusts the pressure of the passing hydraulic oil by reducing the pressure according to the opening of a main valve (not shown).
- the signal pressure adjusting valve 44 urges the main valve in a direction in which the opening decreases, and a pair of pilot ports 44A and 44B through which the discharge pressure of the first hydraulic pump 11 and the discharge pressure of the second hydraulic pump 21 are respectively guided. Return spring 44C.
- the signal pressure adjusting valve 44 is connected to the main pressure by the balance between the discharge pressure of the first hydraulic pump 11 and the discharge pressure of the second hydraulic pump 21 guided from the pair of pilot ports 44A and 44B, respectively, and the urging force of the return spring 44C.
- the opening degree of the valve is changed and the pressure reduction ratio is set.
- the main valve moves due to the discharge pressure, the opening degree increases, and the pressure reduction ratio of the signal pressure adjustment valve 44 decreases.
- the main valve is moved by the return spring 44C, the opening degree is reduced, and the pressure reduction ratio of the signal pressure adjusting valve 44 is increased.
- the signal pressure adjusting valve 44 sets a pressure reduction ratio for reducing the pressure of the hydraulic fluid that passes therethrough according to the sum of the discharge pressures of the first hydraulic pump 11 and the second hydraulic pump 21.
- the hydraulic oil that has not been led to the signal pressure adjusting valve 44 is circulated to the tank through the return passage 45.
- the signal source pressure PP output from the pilot pump 43 is guided to the signal pressure adjusting valve 44.
- the signal pressure adjustment valve 44 reduces the signal source pressure PP to generate a signal pressure PS by a pressure reduction ratio set according to the sum of the discharge pressures of the first hydraulic pump 11 and the second hydraulic pump 21.
- the first pressure adjustment unit 50 is a first command pressure selection valve 51 as a first high pressure selection valve that selects the high pressure side of the two first command pressures P1 and P2 for commanding control of the left drive wheel 2. And a first command pressure adjusting valve 52 that adjusts the first command pressures P1 and P2 on the high pressure side selected by the first command pressure selection valve 51 and guides them to the first pump control unit 13.
- the first command pressure selection valve 51 is a shuttle valve that guides the high pressure side of the first command pressures P1 and P2 guided to the two input ports to the output port.
- the first command pressure adjusting valve 52 is a pressure reducing valve that reduces the pressure of the passing hydraulic oil.
- a signal pressure PS generated by the signal pressure adjusting valve 44 is guided to the first command pressure adjusting valve 52 as a pilot pressure for setting the pressure reduction ratio.
- the first command pressure adjusting valve 52 adjusts the first command pressure P1 or the first command pressure P2 by a pressure reduction ratio set according to the signal pressure PS.
- control pressure P5 the first command pressure P1 or the first command pressure P2 adjusted by the first command pressure adjustment valve 52 is referred to as “control pressure P5”.
- the second pressure adjusting unit 60 is a second command pressure selection valve 61 as a second high pressure selection valve that selects the high pressure side of the two second command pressures P3 and P4 for commanding the control of the right drive wheel 3. And a second command pressure adjusting valve 62 that adjusts the second command pressures P3 and P4 on the high pressure side selected by the second command pressure selection valve 61 and guides them to the second pump control unit 23.
- the second command pressure selection valve 61 is a shuttle valve that guides the high pressure side of the second command pressures P3 and P4 guided to the two input ports to the output port.
- the second command pressure adjusting valve 62 is a pressure reducing valve that reduces the pressure of the passing hydraulic oil.
- the signal pressure PS generated by the signal pressure adjusting valve 44 is guided to the second command pressure adjusting valve 62 as a pilot pressure for setting the pressure reducing ratio.
- the second command pressure adjusting valve 62 adjusts the second command pressure P3 or the second command pressure P4 with a pressure reduction ratio set according to the signal pressure PS.
- control pressure P6 the second command pressure P3 or the second command pressure P4 adjusted by the second command pressure adjustment valve 62 is referred to as “control pressure P6”.
- the 1st change-over valve 53 which operates by the pressure difference of two 1st command pressures P1 and P2 is provided.
- a second switching valve 63 that is operated by a pressure difference between the second command pressures P3 and P4 is provided between the second command pressure adjustment valve 62 and the second pump control unit 23.
- the control pressure P5 and the control pressure P6 adjusted by the first command pressure adjusting valve 52 and the second command pressure adjusting valve 62 are supplied to the first pump control unit 13 and the first switch valve 53 and the second switch valve 63, respectively. Guided to the second pump control unit 23.
- the first switching valve 53 guides the control pressure P5 to the first forward rotation port 13A of the first pump control unit 13 and shuts off the first reverse rotation port 13B, and a first position of the first pump control unit 13 A second position 53B that shuts off the forward rotation port 13A and guides the control pressure P5 to the first reverse rotation port 13B.
- the control pressure P5 adjusted by the first pressure adjusting unit 50 is selectively guided to the first forward rotation port 13A or the first reverse rotation port 13B of the first pump control unit 13 by switching the first switching valve 53.
- the second switching valve 63 guides the control pressure P6 to the second forward rotation port 23A of the second pump control unit 23 and shuts off the second reverse rotation port 23B, A second position 63B that shuts off the second forward rotation port 23A of the second pump control unit 23 and guides the control pressure P6 to the second reverse rotation port 23B.
- the control pressure P6 adjusted by the second pressure adjusting unit 60 is selectively guided to the second forward rotation port 23A or the second reverse rotation port 23B of the second pump control unit 23 by switching the second switching valve 63.
- Two first command pressures P1 and P2 and two second command pressures P3 and P4 are guided to the first switching valve 53 and the second switching valve 63 as pilot pressures for switching positions.
- the first switching valve 53 and the second switching valve 63 are connected to the first pump control unit 13 and the second pump according to the pressure difference between the first command pressures P1 and P2 and the second command pressures P3 and P4 respectively guided as pilot pressures.
- the control unit 23 determines whether to move the swash plates of the first hydraulic pump 11 and the second hydraulic pump 21 in the forward direction or in the reverse direction.
- the work vehicle on which the hydraulic drive system 100 is mounted is controlled in the number of revolutions of the engine 4 according to the amount of depression of an accelerator pedal (not shown), and the traveling state is controlled by operating the joystick 31 of the operation unit 30.
- the rotation direction and the rotation speed ratio of the left and right drive wheels 2 and 3 are controlled in accordance with the tilting direction (operation direction) of the joystick 31, and the traveling operation such as rectilinear movement, backward movement, and turning is controlled.
- two first command pressures P1 and P2 for controlling the left drive wheel 2 and two second command pressures P3 and P4 for controlling the right drive wheel 3 Are generated and output in response to operation inputs.
- the speed ratio of the power of the engine 4 transmitted to the left and right drive wheels 2 and 3 is controlled independently according to the first command pressures P1 and P2 and the second command pressures P3 and P4, so that the vehicle travels.
- the state can be controlled. For example, the vehicle moves forward or backward by rotating the left and right drive wheels 2 and 3 in the same direction at the same rotational speed. Further, the vehicle turns by rotating the left and right drive wheels 2 and 3 in the same rotational direction at different rotational speeds. By changing the rotational speeds of the left and right drive wheels 2 and 3, the forward and backward speeds, turning speed, and turning radius can be controlled.
- the left and right drive wheels 2 and 3 have the same rotation speed in the forward direction, that is, the rotation speed ratio between the left and right drive wheels 2 and 3 is 1: 1.
- 31 outputs the first command pressures P1 and P2 and the second command pressures P3 and P4.
- the first command is issued from the joystick 31 so that the rotational speed in the forward direction of the left drive wheel 2 is smaller than the rotational speed in the forward direction of the right drive wheel 3.
- Pressures P1 and P2 and second command pressures P3 and P4 are output. Further, by outputting the first command pressures P1 and P2 and the second command pressures P3 and P4 so that the left and right drive wheels 2 and 3 rotate in opposite directions, the vehicle can be turned on the spot.
- the first power transmission unit 10 and the second power transmission unit 20 have the same configuration, and the first pressure adjustment unit 50 and the second pressure adjustment unit 60 have the same configuration.
- the operations of the first power transmission unit 10 and the first pressure adjustment unit 50 and the operations of the second power transmission unit 20 and the second pressure adjustment unit 60 are the same except that the driving wheels to be controlled are different. Therefore, in the following, the first power transmission unit 10 and the first pressure adjustment unit 50 that mainly control the left driving wheel 2 will be specifically described, and the second power transmission unit 20 and the second pressure adjustment unit 60 will be described. Description is omitted.
- the two first command pressures P1, P2 for commanding the control of the left drive wheel 2 output from the operation unit 30 are selected by the first command pressure selection valve 51 to be high pressures, and the first command pressures P1, P2 The command pressure on the high pressure side is input to the first command pressure adjustment valve 52.
- the high pressure side of the first command pressures P1 and P2 input to the first command pressure adjustment valve 52 is reduced according to the pressure reduction ratio of the first command pressure adjustment valve 52 and adjusted to the control pressure P5.
- the control pressure P5 adjusted by the first command pressure adjusting valve 52 is a first pump control unit according to the position of the first switching valve 53 set according to the pressure difference between the two first command pressures P1 and P2.
- the first 13 normal rotation ports 13A or 13 reverse rotation ports 13B are selectively guided.
- the first command pressure selection valve The first command pressure P1 is selected by 51 and guided to the first command pressure adjustment valve 52.
- the first switching valve 53 is switched to the first position 53A by the first command pressure P1 on the high pressure side. Therefore, the first command pressure P1 is reduced by the pressure reduction ratio of the first command pressure adjustment valve 52 and adjusted to the control pressure P5.
- the control pressure P5 is guided to the first forward rotation port 13A of the first pump control unit 13 through the first switching valve 53. That is, the first command pressure P1 is the first normal rotation command pressure that switches the first switching valve 53 so that the control pressure P5 is input to the first normal rotation port 13A provided in the first pump control unit 13.
- the first pump control unit 13 moves the swash plate of the first hydraulic pump 11 to a forward tilt angle corresponding to the magnitude of the control pressure P5 guided to the first forward rotation port 13A.
- the 1st hydraulic pump 11 discharges hydraulic fluid from one supply / discharge port 11A. That is, the discharge direction of the first hydraulic pump 11 is controlled to one of the two discharge directions.
- the first hydraulic pump 11 discharges hydraulic oil with a discharge capacity corresponding to the tilt angle amount of the swash plate, that is, the control pressure P5.
- the first command pressure selection valve 51 selects the first command pressure P2 and the first command pressure adjustment valve. 52.
- the first switching valve 53 is switched to the second position 53B by the first command pressure P2 on the high pressure side. Therefore, the first command pressure P2 is reduced by the pressure reduction ratio of the first command pressure adjustment valve 52 and adjusted to the control pressure P5.
- the control pressure P5 is guided to the first reverse rotation port 13B of the first pump control unit 13 through the first switching valve 53. That is, the first command pressure P2 is the first reverse command pressure that switches the first switching valve 53 so that the control pressure P5 is input to the first reverse port 13B provided in the first pump control unit 13.
- the first pump control unit 13 moves the swash plate of the first hydraulic pump 11 to a reverse tilt angle according to the magnitude of the control pressure P5 guided to the first reverse rotation port 13B.
- the first hydraulic pump 11 discharges hydraulic oil from the other supply / discharge port 11B. That is, the discharge direction of the first hydraulic pump 11 is controlled to the other of the two discharge directions.
- the first hydraulic pump 11 discharges hydraulic oil with a discharge capacity corresponding to the tilt angle amount of the swash plate, that is, the control pressure P5.
- the first hydraulic pump 11 of the hydraulic drive system 100 controls the swash plate angle in the forward rotation direction according to the magnitude of the first command pressure P1.
- the first hydraulic pump 11 controls the swash plate angle in the reverse direction according to the magnitude of the first command pressure P2.
- the first hydraulic pump 11 is controlled, and the first hydraulic motor 12 is driven according to the hydraulic oil discharged from the first hydraulic pump 11, so that the left drive connected to the first hydraulic motor 12 is driven.
- the power of the engine 4 is transmitted to the wheel 2 in accordance with the magnitude of the first command pressure P1 or the first command pressure P2 output from the operation unit 30.
- the second hydraulic pump 21 of the hydraulic drive system 100 controls the swash plate angle in the forward rotation direction according to the magnitude of the second command pressure P3 when the second command pressure P3 is high.
- the second hydraulic pump 21 controls the swash plate angle in the reverse rotation direction according to the magnitude of the second command pressure P4. That is, the second command pressure P3 is the second forward rotation command pressure, and the second command pressure P4 is the second reverse rotation command pressure.
- the second hydraulic pump 21 is controlled, and the second hydraulic motor 22 is driven in accordance with the hydraulic oil discharged from the second hydraulic pump 21, whereby the right drive wheel connected to the second hydraulic motor 22.
- the power of the engine 4 is transmitted according to the magnitude of the second command pressure P3 or the second command pressure P4 output from the operation unit 30.
- only one of the first command pressure P1 and the first command pressure P2 that commands control by the first pump control unit 13 may be selectively output from the operation unit 30.
- one of the first command pressure P1 and the first command pressure P2 may be output from the operation unit 30 as zero.
- one of the second command pressure P3 and the second command pressure P4 that commands control by the second pump control unit 23 may be output from the operation unit 30 as zero.
- the hydraulic drive system 100 operates in the same manner as described above. How the operation unit 30 generates the command pressure is arbitrarily set according to the operation input.
- the signal pressure adjusting valve 44 includes hydraulic oil discharged from the first hydraulic pump 11 by the first discharge pressure selection valve 41 and hydraulic oil discharged from the second hydraulic pump 21 by the second discharge pressure selection valve 42. Is discharged as a pilot pressure.
- the signal pressure adjusting valve 44 has a pressure reduction ratio set according to the sum of the discharge pressures of the first hydraulic pump 11 and the second hydraulic pump 21.
- the signal source pressure PP discharged from the pilot pump 43 is guided to the signal pressure adjusting valve 44 as an input pressure.
- the signal pressure PS is generated by reducing and adjusting the signal source pressure PP according to the pressure reduction ratio set according to the sum of the discharge pressures of the first hydraulic pump 11 and the second hydraulic pump 21.
- the signal pressure PS generated by the signal pressure adjustment valve 44 is guided to each as a pilot pressure that sets the pressure reduction ratio of the first command pressure adjustment valve 52 and the second command pressure adjustment valve 62.
- the first command pressure adjusting valve 52 and the second command pressure adjusting valve 62 are controlled from the first command pressure P1, P2 and the second command pressure P3, P4 to the control pressure P5 and control, respectively.
- a pressure reduction ratio for generating the pressure P6 is set. That is, the control pressure P5 and the control pressure P6 guided to the first pump control unit 13 and the second pump control unit 23 are adjusted according to the sum of the discharge pressures of the first hydraulic pump 11 and the second hydraulic pump 21.
- the discharge pressures of the first hydraulic pump 11 and the second hydraulic pump 21 are increased according to the load.
- the pressure reduction ratio of the signal pressure adjusting valve 44 is set according to the increased discharge pressure. That is, as the discharge pressure increases due to the load, the pressure reduction ratio of the signal pressure adjustment valve 44 decreases, and the signal pressure PS guided to the first command pressure adjustment valve 52 and the second command pressure adjustment valve 62 increases. For this reason, the pressure reduction ratio of the first command pressure adjustment valve 52 and the second command pressure adjustment valve 62 increases, and the control pressure P5 and the control pressure adjusted by the first command pressure adjustment valve 52 and the second command pressure adjustment valve 62 are increased. The magnitude of P6 decreases.
- the first pump control unit 13 and the second pump control unit 23 receive the control pressure P5 and the control pressure P6 that are reduced by the load acting on the left and right drive wheels 2 and 3, and thereby the first and second hydraulic pumps 11 and 2 are guided. Control is performed such that each swash plate angle of the hydraulic pump 21 is reduced to reduce the discharge capacity. Since the discharge capacities of the first hydraulic pump 11 and the second hydraulic pump 21 are reduced, the load acting on the first hydraulic pump 11 and the second hydraulic pump 21 is suppressed. As described above, in the hydraulic drive system 100, output control for suppressing the load on the engine 4 can be performed by suppressing the load acting on the first hydraulic pump 11 and the second hydraulic pump 21.
- the hydraulic drive system 300 includes a first power transmission unit 10, a second power transmission unit 20, and an operation unit 30, and includes a first pressure adjustment unit 50, a second pressure adjustment unit 60, a signal pressure. It differs from the hydraulic drive system 100 in that the adjusting valve 44 and the pilot pump 43 are not provided.
- the first pump control unit 13 and the second pump control unit 23 of the hydraulic drive system 300 have a pressure reduction ratio set according to the discharge pressures of the first hydraulic pump 11 and the second hydraulic pump 21, respectively.
- the first pump control unit 13 sets the swash plate angle of the first hydraulic pump 11. Control and reduce discharge volume. As a result, the flow rate of the hydraulic oil guided to the first hydraulic motor 12 is reduced, so that the rotational speed of the left drive wheel 2 is reduced.
- the second pump control unit 23 since the discharge pressure does not increase due to the load on the left driving wheel 2, the second pump control unit 23 does not control the discharge capacity of the second hydraulic pump 21. That is, the rotational speed of the right drive wheel 3 is maintained.
- the hydraulic drive system 100 when a load is applied only to one of the left and right drive wheels 2, 3, for example, the left drive wheel 2, as in the hydraulic drive system 300, Only the discharge pressure increases and the discharge pressure of the second hydraulic pump 21 does not change. Even in this case, since the pressure reduction ratio of the signal pressure adjusting valve 44 is set by the sum of the discharge pressures of the first hydraulic pump 11 and the second hydraulic pump 21, the signal pressure PS is loaded by the signal pressure adjusting valve 44. Will be adjusted according to. Since the signal pressure PS adjusted according to the load is led to the first command pressure regulating valve 52 and the second command pressure regulating valve 62, the respective controls led to the first pump control unit 13 and the second pump control unit 23. The pressure P5 and the control pressure P6 are also generated according to the load. Therefore, the tilt angle of both the first hydraulic pump 11 and the second hydraulic pump 21 is adjusted according to the load of one drive wheel, and the discharge capacity is reduced.
- the control pressure P5 and the control pressure P6 are adjusted.
- the control pressure P5 and the control pressure P6 adjusted in this way are input to the first pump control unit 13 and the second pump control unit 23, respectively.
- the first pump control unit 13 and the second pump control unit 23 respectively control the discharge capacities of both the first hydraulic pump 11 and the second hydraulic pump 21 according to the load.
- the first command pressures P1 and P2 and the second command pressures P3 and P4 for commanding the first pump control unit 13 and the second pump control unit 23 are the first hydraulic pump 11 and the second pump pressure control unit 23, respectively.
- the control pressure P5 and the control pressure P6 are adjusted by the signal pressure PS generated according to the sum of the discharge pressures of the hydraulic oil guided from the two hydraulic pumps 21.
- the discharge pressures of the first hydraulic pump 11 and the second hydraulic pump 21 increase, so that the signal pressure PS is adjusted by the signal pressure generation unit 40 according to the increased discharge pressure.
- the first command pressures P1 and P2 and the second command pressures P3 and P4 for commanding the control by the first pump control unit 13 and the second pump control unit 23 are adjusted according to the increased discharge pressure. Therefore, the load acting on the first hydraulic pump 11 and the second hydraulic pump 21 is suppressed. Therefore, the load on the engine 4 can be suppressed.
- the control pressure P5 and the control adjusted according to the signal pressure PS generated according to the load The pressure P6 is input to each of the first pump control unit 13 and the second pump control unit 23. For this reason, even when a load is applied to only one of the left and right drive wheels 2, 3, the discharge capacities of both the first hydraulic pump 11 and the second hydraulic pump 21 decrease at the same rate, and the left and right drive wheels A rotation speed ratio of 2 or 3 is maintained. In this way, the discharge capacity of both the first hydraulic pump 11 and the second hydraulic pump 21 is reduced while maintaining the rotation speed ratio between the left and right drive wheels 2, 3. Output control that suppresses the load can be performed. Therefore, it is possible to suppress a load acting on the engine 4 and to prevent a traveling operation that is not intended by the operator.
- the first pressure adjusting unit 50 and the second pressure adjusting unit 60 select the high pressure side among the first command pressures P1 and P2 and the second command pressures P3 and P4 output from the operation unit 30, respectively.
- the first command pressure selection valve 51 and the second command pressure selection valve 61 are provided. Then, the high command pressure is selected by the first command pressure selection valve 51 and the second command pressure selection valve 61, and the high pressure side of the first command pressures P1, P2 and the second command pressures P3, P4 is the first command pressure.
- the first pressure adjustment unit 150 of the hydraulic drive system 200 changes one of the first command pressures P1 and P2 to the first command pressure P1 according to the signal pressure PS.
- a first check valve 153 that is provided between the adjustment valve 151 and the first pump control unit 13 and guides pressure only from the third command pressure adjustment valve 151 to the first pump control unit 13, and a fourth command pressure adjustment valve 152.
- the second pressure adjusting unit 160 of the hydraulic drive system 200 includes a fifth command pressure adjusting valve 161 that adjusts one of the two command pressures P3 and P4 according to the signal pressure PS.
- a sixth command pressure adjusting valve 162 that adjusts the other second command pressure P4 of the two second command pressures P3 and P4 according to the signal pressure PS, a fifth command pressure adjusting valve 161, and a second pump control unit.
- a third check valve 163 that guides pressure only from the fifth command pressure adjustment valve 161 to the second pump control unit 23, and a sixth command pressure adjustment valve 162 and the second pump control unit 23.
- a fourth check valve 164 that is provided in between and guides pressure only from the sixth command pressure adjusting valve 162 to the second pump control unit 23.
- the hydraulic drive system 200 is different from the hydraulic drive system 100 in this respect.
- the first check valve 153 is closed by the control pressure P8 when the control pressure P8 adjusted by the fourth command pressure adjustment valve 152 is larger than the control pressure P7 adjusted by the third command pressure adjustment valve 151.
- the control pressure P7 is prevented from being guided to the first pump control unit 13.
- the first check valve 153 is opened by the control pressure P7 when the control pressure P7 is higher than the control pressure P8, and allows the control pressure P7 to be guided to the first pump control unit 13.
- the first check valve 153 guides pressure only from the third command pressure adjustment valve 151 to the first pump control unit 13.
- the second check valve 154 is closed by the control pressure P7 when the control pressure P7 is higher than the control pressure P8, and prevents the control pressure P8 from being guided to the first pump control unit 13.
- the second check valve 154 is opened by the control pressure P8 when the control pressure P8 is higher than the control pressure P7, and allows the control pressure P8 to be guided to the first pump control unit 13.
- the second check valve 154 guides pressure only from the fourth command pressure adjustment valve 152 to the first pump control unit 13.
- the third check valve 163 is closed by the control pressure P10 when the control pressure P10 adjusted by the sixth command pressure adjusting valve 162 is larger than the control pressure P9 adjusted by the fifth command pressure adjusting valve 161.
- the control pressure P9 is prevented from being guided to the second pump control unit 23.
- the third check valve 163 is opened by the control pressure P9 when the control pressure P9 is higher than the control pressure P10, and allows the control pressure P9 to be guided to the second pump control unit 23.
- the third check valve 163 guides the pressure only from the fifth command pressure adjusting valve 161 to the second pump control unit 23.
- the fourth check valve 164 is closed by the control pressure P9 when the control pressure P9 is higher than the control pressure P10, and prevents the control pressure P10 from being guided to the second pump control unit 23.
- the fourth check valve 164 is opened by the control pressure P10 when the control pressure P10 is higher than the control pressure P9, and allows the control pressure P10 to be guided to the second pump control unit 23.
- the fourth check valve 164 guides pressure only from the sixth command pressure adjustment valve 162 to the second pump control unit 23.
- the signal pressure PS generated by the signal pressure adjustment valve 44 is branched into four, the third command pressure adjustment valve 151, the fourth command pressure adjustment valve 152, the fifth command pressure adjustment valve 161, And the sixth command pressure regulating valve 162 is guided as a pilot pressure for setting a pressure reduction ratio.
- the third command pressure adjustment valve 151, the fourth command pressure adjustment valve 152, the fifth command pressure adjustment valve 161, and the sixth command pressure adjustment valve 162 are respectively the first command pressure adjustment valve 52 and the second command pressure adjustment valve 52 of the hydraulic drive system 100. This is a pressure reducing valve similar to the command pressure adjusting valve 62.
- One first command pressure P1 for commanding the control of the left driving wheel 2 output from the operation unit 30 is guided to the third command pressure adjusting valve 151 and also to the first switching valve 53 as a pilot pressure.
- the other first command pressure P2 is guided to the fourth command pressure adjusting valve 152 and also to the first switching valve 53 as a pilot pressure.
- the position of the first switching valve 53 is switched by the pressure difference between the first command pressure P1 and the first command pressure P2.
- One second command pressure P3 for commanding control of the right drive wheel 3 output from the operation unit 30 is guided to the fifth command pressure adjusting valve 161 and also to the second switching valve 63 as pilot pressure.
- the other second command pressure P4 is guided to the sixth command pressure adjusting valve 162 and also to the second switching valve 63 as a pilot pressure.
- the position of the second switching valve 63 is switched by the pressure difference between the second command pressure P3 and the second command pressure P4.
- the first pressure adjustment unit 150 and the second pressure adjustment unit 160 have the same configuration and operation. Therefore, in the following, the first pressure adjustment unit 150 will be specifically described mainly, and the description of the second pressure adjustment unit 160 will be omitted.
- the first command pressure P1 is adjusted to the control pressure P7 by the third command pressure adjustment valve 151 whose pressure reduction ratio is set by the signal pressure PS.
- the command pressure P2 is adjusted to the control pressure P8 by the fourth command pressure adjustment valve 152 whose pressure reduction ratio is set by the signal pressure PS.
- the first check valve 153 is opened by the pressure difference between the control pressure P7 and the control pressure P8, and the second check valve 154 is closed. Therefore, the control pressure P7 is guided to the first switching valve 53 as an input pressure.
- the control pressure P7 is greater than the control pressure P8, that is, when the first command pressure P1 is greater than the first command pressure P2, the first switching valve 53 is switched to the first position 53A. For this reason, the control pressure P ⁇ b> 7 is guided to the first forward rotation port 13 ⁇ / b> A of the first pump control unit 13.
- control pressure P8 When the control pressure P8 is larger than the control pressure P7, the second check valve 154 is opened by the pressure difference between the control pressure P7 and the control pressure P8, and the first check valve 153 is closed. Therefore, the control pressure P8 is guided to the first switching valve 53 as an input pressure.
- control pressure P8 is greater than the control pressure P7, that is, when the first command pressure P2 is greater than the first command pressure P1
- the first switching valve 53 is switched to the second position 53B. Therefore, the control pressure P8 is guided to the first reverse rotation port 13B of the first pump control unit 13.
- the control pressure P7 obtained by adjusting one first command pressure P1 by the third command pressure adjustment valve 151 and the other first command pressure P2 are adjusted by the fourth command pressure adjustment valve 152.
- the control pressure P8 is selected to be high, and the control pressure P7 or the control pressure P8 is guided to the first pump control unit 13. Therefore, according to the said 2nd Embodiment, there exists an effect similar to the said 1st Embodiment.
- a first switching valve 53 is provided between the first pump control unit 13 and the first pressure adjustment unit 150, and between the second pump control unit 23 and the second pressure adjustment unit 160. Is provided with a second switching valve 63.
- a first check valve 153 and a second check valve 154 are provided between the third command pressure adjusting valve 151 and the fourth command pressure adjusting valve 152 and the first switching valve 53, respectively.
- a third check valve 163 and a fourth check valve 164 are provided between the fifth command pressure adjustment valve 161 and the sixth command pressure adjustment valve 162 and the second switching valve 63, respectively.
- the hydraulic drive system 200 may not include the first switching valve 53, the first check valve 153, and the second check valve 154. Further, the hydraulic drive system 200 may not include the second switching valve 63, the third check valve 163, and the fourth check valve 164. That is, the control pressure P7 adjusted by the third command pressure adjusting valve 151 is directly guided to the first forward rotation port 13A of the first pump control unit 13, and the control pressure P8 adjusted by the fourth command pressure adjusting valve 152 is obtained. It may be guided directly to the first reverse rotation port 13B of the first pump control unit 13.
- control pressure P9 adjusted by the fifth command pressure adjusting valve 161 is directly guided to the second forward rotation port 23A of the second pump control unit 23 and adjusted by the sixth command pressure adjusting valve 162.
- the control pressure P ⁇ b> 10 may be directly guided to the second reverse rotation port 23 ⁇ / b> B of the second pump control unit 23.
- the first pump control unit 13 discharges the first hydraulic pump 11 according to the magnitude of the control pressure P7 or the control pressure P8. Control the direction and discharge capacity.
- the second pump control unit 23 discharges the second hydraulic pump 21 according to the control pressure P9 or the control pressure P10. And control the discharge capacity.
- the first pump control unit 13 determines the first hydraulic pump 11 according to the pressure difference between the control pressure P7 and the control pressure P8. The discharge direction and discharge capacity of the liquid are controlled. Similarly, when both the command pressure P3 and the command pressure P4 are output as pressures greater than zero, the second pump control unit 23 selects the second hydraulic pump according to the pressure difference between the control pressure P9 and the control pressure P10. 21 controls the discharge direction and discharge capacity.
- the hydraulic drive systems 100 and 200 are driven by the motive power of the engine 4 and can be changed in the discharge capacity and discharge direction of the hydraulic oil, and the operation discharged from the first hydraulic pump 11.
- a first hydraulic motor 12 that is driven by oil and transmits power to the left drive wheel 2 of the left and right drive wheels 2 and 3, and the left and right drive wheels 2 that are driven by hydraulic oil discharged from the second hydraulic pump 21. 3, the second hydraulic motor 22 that transmits power to the right drive wheel 3, and the discharge capacity and discharge of the first hydraulic pump 11 according to the first command pressures P ⁇ b> 1 and P ⁇ b> 2 generated according to the operator's operation.
- the first pump control unit 13 that controls the direction
- the second pump control that controls the discharge capacity and the discharge direction of the second hydraulic pump 21 according to the second command pressures P3 and P4 generated according to the operation of the operator. 23 and the first command pressures P1, P2 and the second command pressures P3, P4 according to the sum of the discharge pressures of the hydraulic oil discharged from the first hydraulic pump 11 and the second hydraulic pump 21, respectively.
- a signal pressure generating unit 40 that generates the signal pressure PS, first pressure adjusting units 50 and 150 that adjust the first command pressures P1 and P2 according to the signal pressure PS generated by the signal pressure generating unit 40, and a signal pressure Second pressure adjusting units 60 and 160 for adjusting the second command pressures P3 and P4 according to the signal pressure PS generated by the generating unit 40.
- the first command pressures P1 and P2 and the second command pressures P3 and P4 for commanding control to the first pump control unit 13 and the second pump control unit 23 are the same as those of the first hydraulic pump 11.
- the first command pressures P1 and P2 and the second command pressures P3 and P4 for commanding the control by the first pump control unit 13 and the second pump control unit 23 are adjusted according to the increased discharge pressure. Therefore, the load acting on the first hydraulic pump 11 and the second hydraulic pump 21 is suppressed.
- two first command pressures P1 and P2 can be input to the first pressure adjustment unit 50, and two second command pressures P3 and P4 can be input to the second pressure adjustment unit 60.
- the first pressure adjustment unit 50 includes a first command pressure selection valve 51 that selects a high pressure side of the two input first command pressures P1 and P2, and a first command pressure selection valve 51.
- a first command pressure adjusting valve 52 that adjusts the selected high first command pressure P1 or first command pressure P2 in accordance with the signal pressure PS and guides it to the first pump control unit 13;
- the adjustment unit 60 includes a second command pressure selection valve 61 that selects a high pressure side of the two input second command pressures P3 and P4, and a high second command pressure selected by the second command pressure selection valve 61.
- the P3 or the second command pressure P4 is adjusted according to the signal pressure PS and the second pump control unit 23 is adjusted.
- Ku has a second command pressure regulating valve 62, the.
- the first command pressures P1 and P2 and the second command pressures P3 and P4 for commanding control to the first pump control unit 13 and the second pump control unit 23 are two first command pressures P1.
- P2 and the two second command pressures P3 and P4 are selected by the first command pressure selection valve 51 and the second command pressure selection valve 61, respectively, to thereby select the first command pressure adjustment valve 52 and the second command pressure adjustment valve 62, respectively.
- the first command pressures P1 and P2 and the second command pressures P3 and P4 guided to the first command pressure adjustment valve 52 and the second command pressure adjustment valve 62 are introduced from the first hydraulic pump 11 and the second hydraulic pump 21, respectively.
- the signal pressure PS is adjusted by the signal pressure PS generated according to the sum of the discharge pressures of hydraulic oil.
- the signal pressure PS is adjusted according to the increased discharge pressure. Is generated by Therefore, the first command pressures P1 and P2 and the second command pressures P3 and P4 for commanding control by the first pump control unit 13 and the second pump control unit 23 are adjusted according to the increased discharge pressure. Therefore, the load acting on the first hydraulic pump 11 and the second hydraulic pump 21 is suppressed.
- the load on the engine 4 can be suppressed.
- the first pressure adjusting unit 150 can include a third command pressure adjusting valve 151 that adjusts one of the two first command pressures P1 and P2 according to the signal pressure PS, and two first command pressures P1 and P1.
- a fourth command pressure adjusting valve 152 that adjusts the other of P2 according to the signal pressure PS, and a third command pressure adjusting valve 151 provided between the third command pressure adjusting valve 151 and the first pump control unit 13.
- a first check valve 153 that guides pressure only to the first pump control unit 13, a fourth command pressure adjustment valve 152 provided between the fourth command pressure adjustment valve 152 and the first pump control unit 13, and the first pump A second check valve 154 for guiding pressure only to the control unit 13,
- the pressure adjustment unit 160 signals the other of the two second command pressures P3 and P4 and the fifth command pressure adjustment valve 161 that adjusts one of the two second command pressures P3 and P4 according to the signal pressure PS.
- a sixth command pressure adjusting valve 162 that adjusts according to the pressure PS, a fifth command pressure adjusting valve 161 and a second pump control unit 23 provided between the fifth command pressure adjusting valve 161 and the second pump control unit 23.
- the pressure is applied only to the second pump control unit 23 from the sixth command pressure adjustment valve 162, which is provided between the third check valve 163 that guides the pressure only to the sixth pressure control valve 162 and the second pump control unit 23. And a fourth check valve 164 for guiding.
- the first command pressures P1 and P2 for commanding the control to the first pump control unit 13 are guided to the third command pressure adjustment valve 151 and the fourth command pressure adjustment valve 152, respectively.
- the second command pressures P3 and P4 are guided to the fifth command pressure adjustment valve 161 and the sixth command pressure adjustment valve 162, respectively, in order to command the two-pump control unit 23 to perform control.
- the first command pressures P1 and P2 and the second command pressures P3 and P4 guided to the third command pressure adjustment valve 151, the fourth command pressure adjustment valve 152, the fifth command pressure adjustment valve 161, and the sixth command pressure adjustment valve 162 Is adjusted by the signal pressure PS generated according to the sum of the discharge pressures of the first hydraulic pump 11 and the second hydraulic pump 21.
- the command pressure on the high pressure side is the first check valve 153 or the second check valve 154.
- the command pressure on the high pressure side is controlled by the third check valve 163 or the fourth check valve 164. 2 is guided to the pump control unit 23.
- the first command pressures P1 and P2 and the second command pressures P3 and P4 for commanding control by the first pump control unit 13 and the second pump control unit 23 are adjusted according to the increased discharge pressure. Therefore, the load acting on the first hydraulic pump 11 and the second hydraulic pump 21 is suppressed.
- the load on the engine 4 can be suppressed.
- the first pump control unit 13 has a first forward rotation port 13A that controls the discharge direction of the first hydraulic pump 11 to one discharge direction when pressure is input, and the pressure And a first reverse rotation port 13B that controls the discharge direction of the first hydraulic pump 11 to the other discharge direction, and the second pump control unit 23 receives the second pressure when the pressure is input.
- first pump control unit 13 and the first pressure adjustment units 50 and 150 or guide the pressure to the first forward rotation port 13A of the first pump control unit 13, or the first pump Of the control unit 13
- a first switching valve 53 that selectively switches whether to introduce pressure to the first reverse rotation port 13B is provided, and between the second pump control unit 23 and the second pressure adjustment units 60 and 160, the second pump control unit 23 is provided.
- a second switching valve 63 is provided for selectively switching between guiding pressure to the second forward rotation port 23A and guiding pressure to the second reverse rotation port 23B of the second pump control unit 23, and two first commands
- One of the pressures P1 and P2 is a first forward rotation command pressure that switches the first switching valve 53 so that the pressure is input to the first forward rotation port 13A of the first pump control unit 13, and the other is the first pump.
- the first reverse rotation command pressure for switching the first switching valve 53 so that the pressure is input to the first reverse rotation port 13B of the control unit 13, and one of the two second command pressures P3 and P4 is the second pump control unit.
- the pressure is input to the second forward rotation port 23A of 23.
- the second forward rotation command pressure for switching the second switching valve 63 so that the other is the second switching valve 63 so that the pressure is input to the second reverse rotation port 23B of the second pump control unit 23.
- Reverse pressure command pressure is provided for selectively switching between guiding pressure to the second forward rotation port 23A and guiding pressure to
- the first command pressures P1 and P2 and the second command pressures P3 and P4 for commanding control to the first pump control unit 13 and the second pump control unit 23 are the same as those of the first hydraulic pump 11.
- the adjusted first command pressures P1 and P2 and second command pressures P3 and P4 are supplied to the first and second pump control units 13 and 23 through the first switching valve 53 and the second switching valve 63, respectively. It is guided to the second forward rotation ports 13A, 23A or the first and second reverse rotation ports 13B, 23B.
- the first switching valve 53 is operated by the first forward rotation command pressure and the first reverse rotation command pressure
- the second switching valve 63 is operated by the second forward rotation command pressure and the second reverse rotation command pressure.
- the hydraulic drive system 100 is not limited to a work vehicle, and may be mounted on other vehicles as long as the left and right drive wheels are controlled independently.
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Abstract
Description
まず、図1を参照して、本発明の第1実施形態に係る油圧駆動システム100の全体構成について説明する。
次に、本発明の第2実施形態に係る油圧駆動システム200について説明する。以下では、上記第1実施形態と異なる点を中心に説明し、上記第1実施形態の油圧駆動システム100と同一の構成には同一の符号を付して説明を省略する。
Claims (4)
- 液圧駆動システムであって、
駆動源の動力によって駆動され作動液の吐出容量及び吐出方向を変更可能な第1液圧ポンプ及び第2液圧ポンプと、
前記第1液圧ポンプから吐出される作動液によって駆動され左右の駆動輪のうち一方に動力を伝達する第1液圧モータと、
前記第2液圧ポンプから吐出される作動液によって駆動され左右の駆動輪のうち他方に動力を伝達する第2液圧モータと、
作業者の操作に応じて生成される第1指令圧に応じて前記第1液圧ポンプの吐出容量及び吐出方向を制御する第1ポンプ制御部と、
作業者の操作に応じて生成される第2指令圧に応じて前記第2液圧ポンプの吐出容量及び吐出方向を制御する第2ポンプ制御部と、
前記第1液圧ポンプ及び前記第2液圧ポンプの吐出圧の和に応じて前記第1指令圧及び前記第2指令圧を調整するための前記信号圧を生成する信号圧生成部と、
前記信号圧生成部によって生成された前記信号圧に応じて前記第1指令圧を調整する第1圧力調整部と、
前記信号圧生成部によって生成された前記信号圧に応じて前記第2指令圧を調整する第2圧力調整部と、を備える液圧駆動システム。 - 請求項1に記載の液圧駆動システムであって、
前記第1圧力調整部には、2つの前記第1指令圧が入力可能であり、
前記第2圧力調整部には、2つの前記第2指令圧が入力可能であり、
前記第1圧力調整部は、
入力される2つの前記第1指令圧のうち高圧側を選択する第1高圧選択弁と、
前記第1高圧選択弁によって選択された高圧の前記第1指令圧を前記信号圧に応じて調整して前記第1ポンプ制御部に導く第1指令圧調整弁と、を有し、
前記第2圧力調整部は、
入力される2つの前記第2指令圧のうち高圧側を選択する第2高圧選択弁と、
前記第2高圧選択弁によって選択された高圧の前記第2指令圧を前記信号圧に応じて調整して前記第2ポンプ制御部に導く第2指令圧調整弁と、を有する液圧駆動システム。 - 請求項1に記載の液圧駆動システムであって、
前記第1圧力調整部には、2つの前記第1指令圧が入力可能であり、
前記第2圧力調整部には、2つの前記第2指令圧が入力可能であり、
前記第1圧力調整部は、
2つの前記第1指令圧のうち一方を前記信号圧に応じて調整する第3指令圧調整弁と、
2つの前記第1指令圧のうち他方を前記信号圧に応じて調整する第4指令圧調整弁と、
前記第3指令圧調整弁と前記第1ポンプ制御部との間に設けられ前記第3指令圧調整弁から前記第1ポンプ制御部へのみ圧力を導く第1逆止弁と、
前記第4指令圧調整弁と前記第1ポンプ制御部との間に設けられ前記第4指令圧調整弁から前記第1ポンプ制御部へのみ圧力を導く第2逆止弁と、を有し、
前記第2圧力調整部は、
2つの前記第2指令圧のうち一方を前記信号圧に応じて調整する第5指令圧調整弁と、
2つの前記第2指令圧のうち他方を前記信号圧に応じて調整する第6指令圧調整弁と、
前記第5指令圧調整弁と前記第2ポンプ制御部との間に設けられ前記第5指令圧調整弁から前記第2ポンプ制御部へのみ圧力を導く第3逆止弁と、
前記第6指令圧調整弁と前記第2ポンプ制御部との間に設けられ前記第6指令圧調整弁から前記第2ポンプ制御部へのみ圧力を導く第4逆止弁と、を有する液圧駆動システム。 - 請求項2に記載の液圧駆動システムであって、
前記第1ポンプ制御部は、圧力が入力されることにより前記第1液圧ポンプの吐出方向を一方の吐出方向に制御する第1正転ポートと、圧力が入力されることにより前記第1液圧ポンプの吐出方向を他方の吐出方向に制御する第1逆転ポートと、を有し、
前記第2ポンプ制御部は、圧力が入力されることにより前記第2液圧ポンプの吐出方向を一方の吐出方向に制御する第2正転ポートと、圧力が入力されることにより前記第2液圧ポンプの吐出方向を他方の吐出方向に制御する第2逆転ポートと、を有し、
前記第1ポンプ制御部と前記第1圧力調整部との間には、前記第1ポンプ制御部の前記第1正転ポートに圧力を導くか、又は前記第1ポンプ制御部の前記第1逆転ポートに圧力を導くかを選択的に切り換える第1切換弁が設けられ、
前記第2ポンプ制御部と前記第2圧力調整部との間には、前記第2ポンプ制御部の前記第2正転ポートに圧力を導くか、又は前記第2ポンプ制御部の前記第2逆転ポートに圧力を導くかを選択的に切り換える第2切換弁が設けられ、
2つの前記第1指令圧は、一方が前記第1ポンプ制御部の前記第1正転ポートに圧力が入力されるように前記第1切換弁を切り換える第1正転指令圧であり、他方が前記第1ポンプ制御部の前記第1逆転ポートに圧力が入力されるように前記第1切換弁を切り換える第1逆転指令圧であり、
2つの前記第2指令圧は、一方が前記第2ポンプ制御部の前記第2正転ポートに圧力が入力されるように前記第2切換弁を切り換える第2正転指令圧であり、他方が前記第2ポンプ制御部の前記第2逆転ポートに圧力が入力されるように前記第2切換弁を切り換える第2逆転指令圧である液圧駆動システム。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
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CN201580037388.5A CN106536252A (zh) | 2014-07-11 | 2015-06-24 | 液压驱动系统 |
KR1020177000208A KR20170015470A (ko) | 2014-07-11 | 2015-06-24 | 액압 구동 시스템 |
EP15818685.8A EP3168076A1 (en) | 2014-07-11 | 2015-06-24 | Hydraulic drive system |
US15/325,104 US20170190249A1 (en) | 2014-07-11 | 2015-06-24 | Liquid pressure drive system |
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JP2014-143485 | 2014-07-11 | ||
JP2014143485A JP2016020105A (ja) | 2014-07-11 | 2014-07-11 | 液圧駆動システム |
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WO2016006454A1 true WO2016006454A1 (ja) | 2016-01-14 |
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US (1) | US20170190249A1 (ja) |
EP (1) | EP3168076A1 (ja) |
JP (1) | JP2016020105A (ja) |
KR (1) | KR20170015470A (ja) |
CN (1) | CN106536252A (ja) |
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US9840143B1 (en) | 2015-05-20 | 2017-12-12 | Hydro-Gear Limited Partnership | Cooling pump assembly and cooling system for utility vehicle |
US10358040B1 (en) | 2015-06-01 | 2019-07-23 | Hydro-Gear Limited Partnership | Drive assembly and system for utility vehicle |
CN106870500B (zh) * | 2017-03-24 | 2018-09-18 | 广西柳工机械股份有限公司 | 平地机的前轮驱动控制阀及前轮驱动液压系统 |
US10494019B1 (en) * | 2018-05-15 | 2019-12-03 | Cnh Industrial America Llc | System and method for executing straight tracking control of a work vehicle |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4047467A (en) * | 1974-12-18 | 1977-09-13 | Ab Bofors | Device for generating oil pressure for an artillery piece or a corresponding unit |
JPS5318803A (en) * | 1976-08-06 | 1978-02-21 | Daikin Ind Ltd | Duplex pump |
US5875631A (en) * | 1996-12-11 | 1999-03-02 | Caterpillar Inc. | Control system for a hydrostatic transmission |
JP2002038530A (ja) * | 2000-07-28 | 2002-02-06 | Komatsu Ltd | 建設機械における走行油圧回路 |
JP2005090676A (ja) * | 2003-09-19 | 2005-04-07 | Uchida Hydraulics Co Ltd | 流量補正バルブ、流量補正バブル装置および静油圧駆動車両 |
US20120152056A1 (en) * | 2010-12-20 | 2012-06-21 | Caterpillar Inc. | Multiple-variator control for split power CVT and hydrostatic transmissions |
EP2740972A2 (de) * | 2012-12-10 | 2014-06-11 | CLAAS Industrietechnik GmbH | Getriebeaggregat für eine landwirtschaftliche Maschine |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2103095C3 (de) * | 1971-01-23 | 1975-02-06 | Robert Bosch Gmbh, 7000 Stuttgart | Betätigungseinrichtung für einen hydrostatischen Antrieb eines Fahrzeugs, insbesondere eines Kraftfahrzeugs mit einem Nebenabtrieb |
DE2813486C2 (de) * | 1977-03-31 | 1986-06-26 | Kabushiki Kaisha Komatsu Seisakusho, Tokio/Tokyo | Steuervorrichtung für Hydraulikpumpen |
WO2011093378A1 (ja) * | 2010-01-28 | 2011-08-04 | 日立建機株式会社 | 油圧作業機 |
DE102011105440A1 (de) * | 2011-06-24 | 2012-12-27 | Robert Bosch Gmbh | Hydrostatischer Fahrantrieb |
US8540048B2 (en) * | 2011-12-28 | 2013-09-24 | Caterpillar Inc. | System and method for controlling transmission based on variable pressure limit |
CN203114168U (zh) * | 2013-01-21 | 2013-08-07 | 中煤科工集团西安研究院 | 一种双履带独立行走钻机液压系统 |
US9328821B2 (en) * | 2013-06-10 | 2016-05-03 | Caterpillar Inc. | Hydrostatic drive system |
-
2014
- 2014-07-11 JP JP2014143485A patent/JP2016020105A/ja active Pending
-
2015
- 2015-06-24 KR KR1020177000208A patent/KR20170015470A/ko not_active Application Discontinuation
- 2015-06-24 US US15/325,104 patent/US20170190249A1/en not_active Abandoned
- 2015-06-24 WO PCT/JP2015/068235 patent/WO2016006454A1/ja active Application Filing
- 2015-06-24 CN CN201580037388.5A patent/CN106536252A/zh active Pending
- 2015-06-24 EP EP15818685.8A patent/EP3168076A1/en not_active Withdrawn
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4047467A (en) * | 1974-12-18 | 1977-09-13 | Ab Bofors | Device for generating oil pressure for an artillery piece or a corresponding unit |
JPS5318803A (en) * | 1976-08-06 | 1978-02-21 | Daikin Ind Ltd | Duplex pump |
US5875631A (en) * | 1996-12-11 | 1999-03-02 | Caterpillar Inc. | Control system for a hydrostatic transmission |
JP2002038530A (ja) * | 2000-07-28 | 2002-02-06 | Komatsu Ltd | 建設機械における走行油圧回路 |
JP2005090676A (ja) * | 2003-09-19 | 2005-04-07 | Uchida Hydraulics Co Ltd | 流量補正バルブ、流量補正バブル装置および静油圧駆動車両 |
US20120152056A1 (en) * | 2010-12-20 | 2012-06-21 | Caterpillar Inc. | Multiple-variator control for split power CVT and hydrostatic transmissions |
EP2740972A2 (de) * | 2012-12-10 | 2014-06-11 | CLAAS Industrietechnik GmbH | Getriebeaggregat für eine landwirtschaftliche Maschine |
Also Published As
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EP3168076A1 (en) | 2017-05-17 |
US20170190249A1 (en) | 2017-07-06 |
KR20170015470A (ko) | 2017-02-08 |
CN106536252A (zh) | 2017-03-22 |
JP2016020105A (ja) | 2016-02-04 |
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