WO1996032593A1 - Dispositif de commande de cylindree destine a une pompe hydraulique de type cylindree variable - Google Patents

Dispositif de commande de cylindree destine a une pompe hydraulique de type cylindree variable Download PDF

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Publication number
WO1996032593A1
WO1996032593A1 PCT/JP1996/001005 JP9601005W WO9632593A1 WO 1996032593 A1 WO1996032593 A1 WO 1996032593A1 JP 9601005 W JP9601005 W JP 9601005W WO 9632593 A1 WO9632593 A1 WO 9632593A1
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WO
WIPO (PCT)
Prior art keywords
pressure
hydraulic pump
pressure receiving
discharge
supplied
Prior art date
Application number
PCT/JP1996/001005
Other languages
English (en)
Japanese (ja)
Inventor
Kenji Morino
Yosuke Oda
Original Assignee
Komatsu Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Komatsu Ltd. filed Critical Komatsu Ltd.
Priority to EP96909349A priority Critical patent/EP0821167A4/fr
Publication of WO1996032593A1 publication Critical patent/WO1996032593A1/fr

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Classifications

    • 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
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/05—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/08—Regulating by delivery pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2205/00—Fluid parameters
    • F04B2205/06—Pressure in a (hydraulic) circuit
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2205/00—Fluid parameters
    • F04B2205/08—Pressure difference over a throttle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B2205/00—Fluid parameters
    • F04B2205/18—Pressure in a control cylinder/piston unit
    • 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
    • F15B2211/20507—Type of prime mover
    • F15B2211/20523—Internal combustion engine
    • 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
    • F15B2211/2053—Type of pump
    • F15B2211/20538—Type of pump constant capacity
    • 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
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
    • 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
    • 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
    • F15B2211/253—Pressure margin control, e.g. pump pressure in relation to load pressure
    • 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40507—Flow control characterised by the type of flow control means or valve with constant throttles or orifices
    • 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
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50563—Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure
    • 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
    • F15B2211/50—Pressure control
    • F15B2211/52—Pressure control characterised by the type of actuation
    • F15B2211/528—Pressure control characterised by the type of actuation actuated by fluid pressure
    • 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
    • F15B2211/50—Pressure control
    • F15B2211/57—Control of a differential pressure
    • 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
    • F15B2211/6057—Load sensing circuits having valve means between output member and the load sensing circuit using directional control valves
    • 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
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7135—Combinations of output members of different types, e.g. single-acting cylinders with rotary motors

Definitions

  • the present invention relates to a displacement control device that controls the displacement of a variable displacement hydraulic pump used in a hydraulic circuit that supplies pressurized oil to a machine such as a construction machine.
  • a hydraulic circuit for supplying pressure oil to the factory such as a construction machine
  • a hydraulic circuit that supplies the discharge pressure oil of a hydraulic pump to the factory via an operation valve. If a closed center type operating valve that shuts off the pump port when in the neutral position is used as the operating valve in this hydraulic circuit, the discharge path of the hydraulic pump will be a dead end when the operating valve is in the neutral position. Since the pressure of the discharge pressure oil becomes high, the driving horsepower consumption of the engine that drives the hydraulic pump increases.
  • a hydraulic pump is a variable displacement hydraulic pump (hereinafter referred to as a variable hydraulic pump).
  • the capacity (discharge rate per rotation) of the variable hydraulic pump is reduced to a small capacity when the differential pressure between the inlet pressure (pump discharge pressure) and the outlet pressure (load pressure) of the operation valve is large, and the differential pressure is reduced.
  • the pressure is small, the pressure is increased so that the differential pressure is kept constant, and the discharge flow rate of the variable hydraulic pump (volume x number of rotations per unit time) is controlled by the opening of the operating valve (pump port and actuator port). With (Communication area between them) is known.
  • the discharge flow rate of the variable hydraulic pump is the number of revolutions per unit time of the capacity X, and is small when the engine speed is low and is large when the engine speed is high even if the capacity is the same. Therefore, even if the opening of the operating valve is the same, the differential pressure between the inlet side pressure and the outlet side pressure is different, so that the capacity of the variable hydraulic pump is large when the engine speed is low even if the opening of the operating valve is the same. However, at high speeds, the capacity of the variable hydraulic pump is reduced, and the discharge flow rate becomes a value commensurate with the opening.
  • the hydraulic circuit shown in Japanese Utility Model Application Laid-Open No. 5-8603 described above uses a fixed displacement hydraulic pump (hereinafter referred to as a fixed hydraulic pump) using an engine that drives a variable hydraulic pump.
  • a hydraulic pump is driven, a drain circuit equipped with a throttle and a relief valve is connected to the discharge path of the fixed hydraulic pump, and the pressure near the fixed hydraulic pump is detected from the connection in the discharge path.
  • the capacity of the variable hydraulic pump is also controlled by the detected pressure.
  • the detected pressure has a value commensurate with the engine speed, so that the capacity of the variable hydraulic pump can be controlled in consideration of the engine speed, and as a result, the discharge flow rate of the variable hydraulic pump can be controlled by the engine. Since the control is performed in consideration of the engine speed, the differential pressure between the pump discharge pressure and the load pressure becomes a value corresponding to the engine speed.
  • a part of the discharge pressure oil of the fixed hydraulic pump is throttled and discharged to the tank via the relief valve, so that the discharge pressure oil cannot be used effectively and the discharge pressure oil cannot be used effectively.
  • pressurized oil is supplied to other hydraulic equipment, the flow rate flowing out to the tank decreases, and the differential pressure across the throttle changes, so the detected pressure differs and the capacity control characteristics of the variable hydraulic pump change. I will.
  • the discharge flow rate of the fixed hydraulic pump may be so small that the hydraulic pressure may not increase to the set pressure of the relief valve. It cannot be controlled in consideration of the rotation speed.
  • the present invention has been made to reduce the discharge flow rate of the variable displacement hydraulic pump when the engine speed is low, thereby improving the fine operability and reducing the discharge pressure oil of the fixed displacement hydraulic pump. It can be used effectively without draining to the tank, and even if the discharge pressure oil is supplied to other hydraulic equipment, the displacement control characteristics of the variable displacement hydraulic pump can be kept constant, and the engine speed is extremely high. It is an object of the present invention to provide a displacement control device for a variable displacement hydraulic pump which can control the displacement of the variable displacement hydraulic pump in consideration of the engine speed even at a low speed. Disclosure of the invention
  • a first aspect of the displacement control device for a variable displacement hydraulic pump according to the present invention is as follows.
  • a cylinder that changes the capacity of the variable displacement hydraulic pump, and controls supply and discharge of the discharge pressure of the variable displacement hydraulic pump to the cylinder A fixed-volume hydraulic pump driven by the same engine together with the variable-volume hydraulic pump, and a throttle provided in a discharge path of the fixed-volume hydraulic pump.
  • the control valve is switched by comparing a differential pressure between the discharge pressure and the load pressure with a set differential pressure that is a differential pressure before and after the throttle, and the variable displacement is performed via the cylinder.
  • the differential pressure is set to a constant value corresponding to the set differential pressure.
  • the discharge flow rate of the variable displacement hydraulic pump is significantly reduced, and the fine operability is improved. Also, since the set differential pressure of the control valve is changed by the differential pressure before and after the throttle provided in the discharge path of the fixed displacement hydraulic pump, the discharge pressure oil of the fixed displacement hydraulic pump flows out to the tank. If the engine speed is constant, then even if the discharge pressure oil of the fixed displacement hydraulic pump is supplied to other hydraulic equipment, the differential pressure before and after the throttle does not change. The displacement control characteristics of the pump can be made constant. Moreover, even when the engine 1 is extremely low speed, a differential pressure across the throttle is generated, and the capacity of the variable displacement hydraulic pump is taken into account in consideration of the engine speed. Can be controlled.
  • a second aspect of the displacement control device for a variable displacement hydraulic pump according to the present invention includes:
  • a cylinder for changing the capacity of the variable displacement hydraulic pump a control valve for controlling the supply and discharge of the discharge pressure of the variable displacement hydraulic pump to the cylinder, and the same as the variable displacement hydraulic pump.
  • a fixed displacement hydraulic pump driven by an engine a throttle provided in a discharge path of the fixed displacement hydraulic pump, and a pilot circuit provided between a downstream side of the throttle and the control valve.
  • a second throttle provided in a drain path connected to a downstream side of the other first throttle, wherein the control valve is configured to control a differential pressure between the discharge pressure and the load pressure.
  • a set differential pressure which is a differential pressure between the upstream side of the throttle and the downstream side of the other first throttle, is switched, and the variable capacity is changed via the cylinder.
  • the differential pressure is regarded as a set differential pressure.
  • Cormorants are those that were to be a constant value.
  • a third aspect of the displacement control device for the variable displacement hydraulic pump according to the present invention is as follows.
  • a cylinder for changing the displacement of the variable displacement hydraulic pump a control valve for controlling supply and discharge of the discharge pressure of the variable displacement hydraulic pump to the cylinder, and a variable displacement hydraulic pump.
  • a fixed displacement hydraulic pump driven by the same engine, a throttle provided in a discharge path of the fixed displacement hydraulic pump, and switching between supply and discharge of the discharge pressure to the control valve and the cylinder And a switching valve linked via a spring.
  • the control valve has a differential pressure between the discharge pressure and the load pressure; and Switching operation is performed by comparison with a set differential pressure, which is a subsequent differential pressure, and by controlling the displacement of the variable displacement hydraulic pump through the cylinder, the differential pressure is set to the set differential pressure. To a constant value that matches
  • the switching valve is switched by comparing the discharge pressure with the mounting load of the spring, and controls the displacement of the variable displacement hydraulic pump via the control valve and the cylinder, thereby controlling the displacement of the variable displacement hydraulic pump.
  • the input torque of the displacement hydraulic pump is made constant.
  • FIG. 1 is a schematic configuration diagram illustrating a first embodiment of a displacement control device for a variable displacement hydraulic pump according to the present invention.
  • FIG. 2 is a chart showing the relationship between the engine speed and the discharge flow rate of the variable hydraulic pump in the first embodiment.
  • FIG. 3 is a cross-sectional view showing a specific structure of the control valve of the first embodiment.
  • FIG. 4 is a diagram illustrating the configuration of a displacement control device for a variable displacement hydraulic pump according to a second embodiment of the present invention.
  • FIG. 5 is a diagram illustrating the configuration of a third embodiment of the displacement control device for a variable displacement hydraulic pump according to the present invention.
  • FIG. 1 shows a first embodiment of a displacement control device for a variable displacement hydraulic pump according to the present invention.
  • engine 1 drives variable displacement hydraulic pump 2 (hereinafter referred to as variable hydraulic pump 2) and fixed displacement hydraulic pump 3 (hereinafter referred to as fixed hydraulic pump 3).
  • the discharge path 4 of the variable hydraulic pump 2 is connected to a pump port 6 of an operation valve 5, and the first and second actuating ports 7 and 8 of the operation valve 5 are connected to the first and second ports, respectively.
  • Circuits 9 and 10 are connected to the first and second chambers 12 and 13 of the factory 11 respectively, and the tank port 14 is connected to the tank 15.
  • the discharge passage 16 of the fixed hydraulic pump 3 is connected to the inlet side of a hydraulic pilot valve 17. By operating the hydraulic pilot valve 17, the hydraulic pressure discharged from the fixed hydraulic pump 3 is supplied to other hydraulic equipment.
  • the discharge path 16 is provided with a throttle 18.
  • the piston 22 has a piston 22 and a large-diameter pressure receiving chamber 23 and a small-diameter pressure receiving chamber 24 defined on both sides of the piston 22, and the piston 22 is a variable hydraulic pump 2. It is a cylinder connected to the stencil 20 of.
  • the swash plate 20 for changing the displacement of the variable hydraulic pump 2 is tilted by the piston 22 of the swash plate control cylinder 21 so that the angle can be changed.
  • the piston 22 of the cylinder 21 moves in the small-capacity direction with the pressure oil in the large-diameter pressure receiving chamber 23, and moves in the large-capacity direction with the pressure oil in the small-diameter pressure receiving chamber 24 and the panel 25. Go to
  • the large-diameter pressure receiving chamber 23 is controlled by a control valve 26 to tank 15 or discharge path 4.
  • the small-diameter pressure receiving chamber 24 is connected to the discharge path 4.
  • the control valve 26 has a first port 27 connected to the discharge path 4 via a small-diameter pressure receiving chamber 24, a second port 28 connected to the large-diameter pressure receiving chamber 23, and a tank port 29.
  • the first port 27 is shut off by the pressure oil of the first pressure receiving part 30 and the pressure oil of the first auxiliary pressure receiving part 31, and the second port 28 is connected to the tank port 29. It is pushed to the drain position A which communicates with the first port 27 and the second port 28 by the pressure oil of the second pressure receiving part 32 and the pressure oil of the second auxiliary pressure receiving part 33, and Pushed to supply position B to shut off tank port 29.
  • the first pressure receiving section 30 is connected to the outlet side of a shuttle valve 19 that detects the higher pressure of the first circuit 9 and the second circuit 10, and is connected to the outlet side pressure (load) of the operation valve 5. Pressure) is supplied.
  • the second pressure receiving portion 32 communicates with the discharge path 4 via the small-diameter pressure receiving chamber 24, and is supplied with the pressure on the inlet side of the operation valve 5 (pump discharge pressure).
  • the first auxiliary pressure receiving portion 31 is connected to the upstream side of the throttle 18, and the second auxiliary pressure receiving portion 33 is connected to the downstream side of the throttle 18.
  • the rotation speed of the engine 1 is controlled by sending a rotation speed command signal issued from an operation member 34 such as an accelerator pedal to the control governor 35 of the engine 1. For example, when the operating member 34 is set at the low speed position a, the rotation speed is low. When the operation member 34 is set at the medium speed position b, the rotation speed is medium.
  • the control valve 26 switches to the supply position B and switches the swash plate 4. Tilt in the small tilt angle direction, and the differential pressure
  • the swash plate 4 is switched to the drain position A and the tilt angle of the swash plate 4 is tilted in the large direction to make the differential pressure between the inlet pressure and the outlet pressure of the operation valve 5 constant, and
  • the discharge flow rate of the variable hydraulic pump 2 is set to a value appropriate for the opening of the control valve 5 (communication area between the pump port 6 and the first or second actuator port 7 or 8).
  • the set differential pressure of the control valve 26 changes depending on the differential pressure before and after the throttle 18, and the differential pressure before and after the throttle 18 changes the discharge flow rate of the fixed hydraulic pump 3 (the number of rotations of essidine). It is proportional to the square.
  • the set differential pressure of the control valve 26 is small when the engine speed is low and large when the engine speed is high.
  • the discharge flow rate of the pump 2 is smaller than at high speed, and the fine operability is improved.
  • the differential pressure before and after the throttle 18 is proportional to the square of the engine speed (discharge flow rate of the fixed hydraulic pump 3) as shown in Fig. 2 (a), and the set differential pressure of the control valve 26 is set. Is linearly proportional to the differential pressure around the throttle 18 as shown in Fig. 2 (b), and the capacity of the variable hydraulic pump 2 is proportional to the square of the set differential pressure as shown in Fig. 2 (c).
  • the discharge flow rate of the variable hydraulic pump 2 is linearly proportional to the engine speed as shown in (d) of FIG.
  • control valve 26 Next, a specific structure of the control valve 26 will be described.
  • a sleeve 42 is inserted and screwed into a sleeve hole 41 formed in a valve body 40 such as a housing of the variable hydraulic pump 2, and the sleeve hole 41 is inserted into the sleeve hole 41.
  • the first inlet port 65, the outlet port 66, the control port 67, the pump pressure supply port 68 and the second inlet port 69 are open, and the sleeve 42 has the first port.
  • Port 43, Second Port 44, Third Port 45, Fourth Port 46, and Fifth Port 4 7 are formed.
  • a spool 48 is slidably fitted in a spool fitting hole 42 a in a shaft portion of the sleeve 42.
  • the spool 48 has a first small-diameter portion 50, a second small-diameter portion 51, and a third small-diameter portion 52.
  • a spool 48 is formed in an axial hole 48a formed at one end of the spool 48.
  • the small-diameter portion 54 of the fixed piston 53 fitted in the fitting hole 42 a is fitted to the first pressure receiving chamber 55 (the second pressure receiving portion 32 in FIG. 1) and the second pressure receiving chamber 56. (The second auxiliary pressure receiving portion 33 in FIG. 1) is formed.
  • the first pressure receiving chamber 55 communicates with the second small-diameter portion 51 through an oil hole 57 formed in the shaft core of the spool 48.
  • the third small-diameter portion 52 penetrates through the shaft core hole 42 c of the sleeve 42 and projects into the spring insertion hole 42 b, whereby the third pressure receiving chamber 5 is formed. 8 are formed.
  • a threaded rod is provided at one end of the spring insertion hole 42b of the sleeve 42.
  • the tip end cylindrical portion 60 of 59 is fitted to define the fourth pressure receiving chamber 61, and the screw rod 59 is screwed to the sleeve 42 and fastened and fixed by the lock nut 62. It has become so.
  • a hole 64 communicating with the fourth pressure receiving chamber 61 via the distal end cylindrical portion 60 from the other end piping joint portion 63 is formed in the shaft core portion of the screw rod 59. .
  • a spring 49 is inserted into the spring input hole 42b so as to be interposed between the other end of the spool 48 and the tip cylindrical portion 60 of the screw rod 59. I have.
  • the pressure receiving diameter d l of the first pressure receiving chamber 55 is equal to the pressure receiving diameter d 2 of the fourth pressure receiving chamber 61.
  • the first port 43 communicates with the second pressure receiving chamber 56 and the first inlet port 65, and the first inlet port 65 is located below the throttle 18 shown in FIG. It is connected to the outlet side.
  • the second port 44 is connected to the outflow port 66 (tank port 29 in FIG. 1), and the outflow port 66 communicates with the tank 15 shown in FIG.
  • the third port 45 is connected to the control port 67 (the second port 28 in FIG. 1), and the control port 67 is connected to the large-diameter pressure receiving chamber 23.
  • the fourth port 46 is connected to the pump pressure supply port 68 (the first port 27 in FIG. 1), and the pump pressure supply port 68 is connected to the discharge passage 4 through the small-diameter pressure receiving chamber 24. It is made to be surrounded.
  • the fifth port 47 is connected to the third pressure receiving chamber 58 (first auxiliary pressure receiving part 31 in FIG. 1) and the second inflow port 69, and the second inflow port 69 is shown in FIG. It is connected upstream of the throttle 18 shown.
  • An unillustrated hose is connected to the other end pipe joint portion 63, and the outlet side pressure (load) of the operation valve 5 is connected to the fourth pressure receiving chamber 61 (the first pressure receiving portion 30 in FIG. 1) via these hoses. Pressure) is supplied.
  • the pump discharge pressure P i of the variable hydraulic pump 2 is supplied from the pump pressure supply port 68 to the fourth port 46, and the second small-diameter portion 5 1.
  • the pressure is supplied to the pressure receiving chamber 55, and the spool 48 is pushed to the right.
  • the output pressure (load pressure) P LS of the operation valve is supplied to the fourth pressure receiving chamber 61, and the spool 48 is moved to the left. Push.
  • the second port is connected to the first small diameter portion 50 of the spool 48.
  • 4 4 communicates with the third port 45 and the control port 67 communicates with the tank 15 via the outflow port 66 so that the control valve 26 is positioned at the drain position A in FIG.
  • the pressure oil in the large-diameter pressure receiving chamber 23 of the swash plate control valve 21 flows out, so that the capacity of the variable hydraulic pump 2 increases.
  • the spool 48 is pushed rightward by the pressure on the downstream side of the throttle 18 acting on the second pressure receiving chamber 56, and is located upstream of the throttle 18 acting on the third pressure receiving chamber 58. It is pushed to the left by pressure, so the spool 4 8 Is pushed to the left by the differential pressure before and after the throttle 18, the set differential pressure is greater than in the previous case.
  • D is the diameter of the spool 48
  • P2 is the pressure upstream of the throttle 18
  • P3 is the pressure downstream of the throttle 18.
  • the discharge flow rate of the fixed hydraulic pump 3 decreases and the throttle 1
  • the set differential pressure drops, and the spool 48 moves to the right, causing the third port 45 and the fourth port 46 to move.
  • the control valve 26 in FIG. 1 is connected to the supply position B so that the discharge pressure of the variable hydraulic pump 2 flows to the control port 67 and is supplied to the large-diameter pressure receiving chamber 23.
  • the swash plate 20 tilts in the small capacity direction, and the capacity of the variable hydraulic pump 2 is reduced, and the discharge flow rate of the variable hydraulic pump 2 is significantly reduced as compared with the high speed.
  • FIG. 4 shows a second embodiment of the displacement control device for a variable displacement hydraulic pump according to the present invention. This is achieved by providing a first throttle 71 in a pilot circuit 70 connecting the downstream side of the throttle 18 in the discharge path 16 of the fixed hydraulic pump 3 and the second auxiliary pressure receiving part 33 of the control valve 26. A downstream side of the first throttle 71 is connected to a tank 15 by a drain circuit 72, and a second throttle 73 is provided in the drain circuit 72.
  • the discharge passage 16 of the fixed hydraulic pump 3 is connected to a swing hydraulic motor 76 by an auxiliary operation valve 75, and the auxiliary operation valve 75 is switched to the supply position. By changing, the swing hydraulic motor 26 is driven.
  • the ratio of the pressure drop is a constant ratio determined by the flow area of the first throttle 71 and the flow area of the second throttle 73.
  • the fixed hydraulic pump 3 is composed of, for example, a gear pump.
  • the discharge pressure of the fixed hydraulic pump 3 increases, the internal leakage increases and the efficiency decreases, so that the discharge flow rate of the fixed hydraulic pump 3 is the same. Also, when the discharge pressure is high, it decreases more than when it is low.
  • the first and second throttles 71 and 73 are not provided in the pilot circuit 70, and the pressure P3 on the downstream side of the throttle 18 is controlled by the second auxiliary receiving pressure of the control valve 26.
  • the differential pressure between the pressure acting on the first auxiliary pressure receiving part 31 of the control valve 26 and the pressure acting on the second auxiliary pressure receiving part 33 causes the swing hydraulic motor 76 to operate. It changes between startup and steady rotation, and the discharge flow rate of the variable hydraulic pump 2 differs.
  • the provision of the first and second throttles 71 and 73 in the pilot circuit 70 acts on the second auxiliary pressure receiving portion 33 of the control valve 26. Since the pressure P 4 becomes lower at a constant rate than the downstream pressure P 3 of the throttle 18, even if the discharge flow rate of the fixed hydraulic pump 3 decreases due to the decrease in efficiency due to the discharge pressure as described above, the control valve 2 The differential pressure between the pressures acting on the first auxiliary pressure receiving part 31 and the second auxiliary pressure receiving part 33 of FIG. 6 becomes almost constant, and the discharge of the variable hydraulic pump 2 depends on when the swing hydraulic motor 76 starts and when it rotates normally. The flow rate does not change.
  • the discharge pressure of the fixed hydraulic pump 3 is 50 kg / cm 2
  • the discharge flow rate is 201 / min
  • the downstream pressure P3 of the throttle 18 is 40 kg / cm 2
  • the pressure P4 of the second auxiliary pressure receiving part 33 is 39.5 kg / cm 2
  • the differential pressure of P4 acting on 3 (P2—P4) is 1 O kg / cm 2 .
  • FIG. 5 shows a displacement control device for a variable displacement hydraulic pump according to the present invention.
  • the second embodiment is shown.
  • the drain port 29 of the control valve 26 is switched to and connected to one of the tank 15 and the discharge path 4 by a switching valve 80 for input torque control.
  • the switching valve 80 is pushed to the drain position C by the spring 81, and is supplied to the supply position by the discharge pressure of the variable displacement pump 2 acting on the first pressure receiving part 82 and the external pressure acting on the second pressure receiving part 83. It is pushed by D. Further, spring 81 is linked to piston 22 at link 84.
  • the switching valve 80 becomes the supply position D. Since the discharge pressure flows into the large-diameter pressure receiving chamber 23 via the control valve 26, the piston 22 moves to the right and the swash plate 20 tilts in the small capacity direction, and the piston 2 By the movement of 2, the mounting load of the spring 81 via the link 84 becomes large, and the switching valve 80 is pushed back to the drain position C.
  • variable hydraulic pump 2 is controlled so that the input torque (pump discharge pressure X capacity) becomes constant.
  • the discharge flow rate of the fixed displacement hydraulic pump 3 is reduced, whereby the differential pressure before and after the throttle 18 is reduced. Becomes smaller, the set differential pressure of the control valve 26 becomes smaller. Also, when the rotation speed of the engine 1 is high, the discharge flow rate of the fixed displacement hydraulic pump 3 is increased, and as a result, the differential pressure across the throttle 18 is increased, and the control valve 26 is set to a higher pressure. The differential pressure increases. Therefore, when the engine 1 is at a low rotational speed, the discharge flow rate of the variable displacement hydraulic pump 2 is significantly reduced, and the fine operability is improved.
  • the discharge pressure of the fixed displacement hydraulic pump 3 is changed.
  • the oil can be used effectively without spilling into the tank 15. If the engine speed is constant, the discharge pressure oil of the fixed displacement hydraulic pump 3 can be throttled even if it is supplied to other hydraulic equipment. Since the pressure difference before and after the pressure does not change, the displacement control characteristics of the variable displacement hydraulic pump 2 can be kept constant. In addition, even when the engine 1 is at a very low speed, a pressure difference around the throttle 18 is generated, and the capacity of the variable displacement hydraulic pump 2 can be controlled in consideration of the engine speed.
  • the pressure P 4 applied to the second auxiliary pressure receiving portion 33 of the control valve 26 is the pressure P 4 downstream of the throttle 18 provided in the discharge passage 16 of the fixed displacement hydraulic pump 3.
  • the pressure P 3 is reduced at a fixed ratio, and the control valve 2 6 is used even if the engine 1 rotation speed is constant and the discharge flow rate changes due to the change in efficiency due to the discharge pressure of the fixed displacement hydraulic pump 3.
  • the pressure difference between the first auxiliary pressure receiving portion 31 and the second auxiliary pressure receiving portion 33 becomes substantially the same.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)

Abstract

Ce dispositif de commande de cylindrée, destiné à une pompe hydraulique de type à cylindrée variable, comprend un cylindre (21) qui fait varier la cylindrée de cette pompe (2), une soupape (26) chargée de commander l'entrée et la sortie de la pression de sortie de la pompe par rapport au cylindre, une pompe hydraulique (3), du type à cylindrée fixe, entraînée, avec la première pompe, par le même moteur (1), et un clapet d'étranglement (18) disposé sur une conduite de sortie de la pompe de type à cylindrée fixe. La soupape de commande se déplace en fonction d'une comparaison entre une pression différentielle, entre la pression de sortie et la pression de charge, et une pression différentielle donnée mesurée dans le clapet d'étranglement de façon que cette soupape commande la cylindrée de la pompe hydraulique à cylindrée variable par l'intermédiaire du cylindre, cette pression différentielle étant alors amenée à une certaine valeur correspondant à la pression différentielle donnée.
PCT/JP1996/001005 1995-04-12 1996-04-11 Dispositif de commande de cylindree destine a une pompe hydraulique de type cylindree variable WO1996032593A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP96909349A EP0821167A4 (fr) 1995-04-12 1996-04-11 Dispositif de commande de cylindree destine a une pompe hydraulique de type cylindree variable

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP7/86697 1995-04-12
JP8669795 1995-04-12
JP7214736A JPH08338405A (ja) 1995-04-12 1995-08-23 可変容量型油圧ポンプの容量制御装置
JP7/214736 1995-08-23

Publications (1)

Publication Number Publication Date
WO1996032593A1 true WO1996032593A1 (fr) 1996-10-17

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP1996/001005 WO1996032593A1 (fr) 1995-04-12 1996-04-11 Dispositif de commande de cylindree destine a une pompe hydraulique de type cylindree variable

Country Status (3)

Country Link
EP (1) EP0821167A4 (fr)
JP (1) JPH08338405A (fr)
WO (1) WO1996032593A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3679300B2 (ja) * 1999-06-10 2005-08-03 日立建機株式会社 可変容量型液圧回転機の容量制御弁
JP2002048235A (ja) * 2000-08-02 2002-02-15 Komatsu Ltd 油圧ポンプの容量制御装置
DE10344152A1 (de) * 2003-09-22 2005-04-21 Klaus Riedel Kombinationsschraube
US11486277B2 (en) 2021-02-26 2022-11-01 Deere & Company Work vehicle engine with split-circuit lubrication system

Citations (3)

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Publication number Priority date Publication date Assignee Title
JPH0599126A (ja) * 1991-10-07 1993-04-20 Komatsu Ltd 可変容量型油圧ポンプの容量制御装置
JPH0586003U (ja) 1992-04-23 1993-11-19 内田油圧機器工業株式会社 ロードセンシング用差圧発生装置
JPH06159309A (ja) * 1992-11-17 1994-06-07 Hitachi Constr Mach Co Ltd 流量制御装置

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DE2141724A1 (de) * 1971-08-20 1973-03-01 Bosch Gmbh Robert Steuer- und regeleinrichtung fuer eine hydropumpe
US4017216A (en) * 1976-03-15 1977-04-12 Caterpillar Tractor Co. Variable underspeed system linkage
KR920007650B1 (ko) * 1989-02-20 1992-09-14 히다찌 겐끼 가부시기가이샤 작업기계의 유압회로장치
DE4115606A1 (de) * 1991-05-14 1992-11-19 Putzmeister Maschf Ueberlast-schutzeinrichtung fuer einen als brennkraftmaschine ausgebildeten antriebsmotor einer hauptpumpe eines hydraulischen druckversorgungsaggregats
JPH05172107A (ja) 1991-12-24 1993-07-09 Komatsu Ltd 可変油圧ポンプの容量制御装置

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0599126A (ja) * 1991-10-07 1993-04-20 Komatsu Ltd 可変容量型油圧ポンプの容量制御装置
JPH0586003U (ja) 1992-04-23 1993-11-19 内田油圧機器工業株式会社 ロードセンシング用差圧発生装置
JPH06159309A (ja) * 1992-11-17 1994-06-07 Hitachi Constr Mach Co Ltd 流量制御装置

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN
See also references of EP0821167A4 *

Also Published As

Publication number Publication date
JPH08338405A (ja) 1996-12-24
EP0821167A4 (fr) 1998-09-02
EP0821167A1 (fr) 1998-01-28

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