EP0821167A1 - Regeleinrichtung für eine hydraulikpumpe mit variabler verdrängung - Google Patents

Regeleinrichtung für eine hydraulikpumpe mit variabler verdrängung Download PDF

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Publication number
EP0821167A1
EP0821167A1 EP96909349A EP96909349A EP0821167A1 EP 0821167 A1 EP0821167 A1 EP 0821167A1 EP 96909349 A EP96909349 A EP 96909349A EP 96909349 A EP96909349 A EP 96909349A EP 0821167 A1 EP0821167 A1 EP 0821167A1
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EP
European Patent Office
Prior art keywords
pressure
hydraulic pump
pressure receiving
type hydraulic
receiving portion
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
EP96909349A
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English (en)
French (fr)
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EP0821167A4 (de
Inventor
Kenji Oyama Factory of Komatsu Ltd. MORINO
Yosuke Oyama Factory of Komatsu Ltd. ODA
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Komatsu Ltd
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Komatsu Ltd
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Publication of EP0821167A1 publication Critical patent/EP0821167A1/de
Publication of EP0821167A4 publication Critical patent/EP0821167A4/de
Ceased legal-status Critical Current

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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
    • F15B11/02—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 system for controlling a displacement of a variable displacement type hydraulic pump to be employed in a hydraulic circuit supplying a pressurized fluid to an actuator of a construction machine or so forth.
  • variable hydraulic pump a variable displacement type hydraulic pump
  • a displacement (a discharge amount per one revolution cycle) of the variable hydraulic pump is controlled to make the displacement smaller when a differential pressure between an inlet side pressure (pump discharge pressure) and an outlet side pressure (load pressure) is large and to make the displacement larger when the differential pressure is small and whereby to make the differential pressure constant
  • a discharge flow rate (displacement x number of revolution per unit period) of the variable hydraulic pump can be a value corresponding to an opening degree (a communication area between a pump port and an actuator port) of the operation valve, as disclosed in Japanese Unexamined Utility Model Publication (Kokai) No. Heisei 5-86003.
  • the discharge flow rate of the variable hydraulic pump is displacement x number of revolution per unit period, and thus becomes small when an engine speed is low and large when the engine speed is high even when the displacement is constant, to differentiate the differential pressure of the inlet side pressure and the outlet side pressure even when the opening degree of the operation valve is the same. Therefore, even when the opening degree of the operation valve is the same, the displacement of the variable hydraulic pump is controlled to be larger when the engine speed is low and to be smaller when the engine speed is high so that the discharge flow rate becomes a value corresponding to the opening degree.
  • the displacement of the variable hydraulic pump becomes larger to increase discharge flow rate of the variable hydraulic pump to make it impossible to perform fine operation.
  • a fixed displacement type hydraulic pump (hereinafter referred to a fixed displacement hydraulic pump) is driven by the engine which drives the variable hydraulic pump, and a drain circuit including a restriction and a relief valve is connected to a discharge passage of the fixed displacement hydraulic pump, a pressure on the side of the fixed displacement hydraulic pump in relation to a junction in the discharge passage is detected to control the displacement of the variable pump depending upon the detected pressure.
  • the displacement of the variable hydraulic pump can be controlled with taking the engine speed into account.
  • the discharge flow rate of the variable hydraulic pump can be controlled with taking the engine speed into account, and whereby the differential pressure of the pump discharge pressure and the load pressure becomes a value corresponding to the engine speed.
  • a displacement control system for a variable displacement type hydraulic pump in which a discharge flow rate of the variable displacement type hydraulic pump becomes extremely small at low engine speed to improve operability in fine operation, a discharged pressurized fluid of a fixed displacement type hydraulic pump can be effectively used without flowing out to a tank, a displacement control characteristics of the variable displacement type hydraulic pump can be maintained constant even when the discharged pressure of the fixed displacement type hydraulic pump is supplied to other hydraulic device, and the displacement of the variable displacement type hydraulic pump can be controlled with taking an engine speed into account even when the engine speed is extremely low.
  • the discharge flow rate of the variable displacement type hydraulic pump becomes extremely small to improve operability in fine operation.
  • the set differential pressure of the control valve is varied by the differential pressure between upstream and downstream of the restriction provided in the discharge passage of the fixed displacement type hydraulic pump, the discharged pressurized fluid of the fixed displacement type hydraulic pump can be used effectively without flowing out to the tank.
  • the differential pressure between upstream and downstream of the restriction is not varied even when the discharged pressurized fluid of the fixed displacement type hydraulic pump is supplied to other hydraulic device, the displacement control characteristics of the variable displacement type hydraulic pump can be constant.
  • the differential pressure between upstream and downstream of the restriction is generated even at extremely low engine speed to enable control with taking the engine speed into account.
  • a displacement control system comprises a cylinder for varying a displacement of the variable displacement type hydraulic pump, a control valve for controlling supply and drain of a discharge pressure of the variable displacement type hydraulic pump to and from the cylinder, a fixed displacement type hydraulic pump driven simultaneously with the variable displacement type hydraulic pump by a common engine and a restriction provided in a discharge passage of the fixed displacement type hydraulic pump, a first additional restriction provided in a pilot circuit between the downstream side of the restriction and the control valve and a second additional restriction provided in a drain passage connected to downstream side of the first additional restriction,
  • a displacement control system for a variable displacement type hydraulic pump comprising a cylinder for varying a displacement of the variable displacement type hydraulic pump, a control valve for controlling supply and drain of a discharge pressure of the variable displacement type hydraulic pump to and from the cylinder, a fixed displacement type hydraulic pump driven simultaneously with the variable displacement type hydraulic pump by a common engine, a restriction provided in a discharge passage of the fixed displacement type hydraulic pump and a switching valve for switching supply and drain of the discharge pressure to and from the control valve and being associated with the cylinder via the spring,
  • Fig. 1 shows the first embodiment of a displacement control system for a variable displacement type hydraulic pump according to the present invention.
  • a variable hydraulic pump 2 hereinafter referred to as a variable hydraulic pump 2
  • a fixed displacement type hydraulic pump 3 hereinafter referred to as a fixed displacement hydraulic pump 3
  • a discharge passage 4 of the variable hydraulic pump 2 is connected to a pump port 6 of an operation valve 5.
  • First and second actuator ports 7 and 8 of the operation valve 5 are respectively connected to a first chamber 12 and a second chamber 13 of an actuator 11 via respective of first and second circuits 9 and 10.
  • a tank port 14 is connected to a tank 15.
  • a discharge passage 16 of the fixed displacement hydraulic pump 3 is connected to an inlet side of a hydraulic pilot valve 17. By operating the hydraulic pilot valve 17, a discharged pressurized fluid of the fixed displacement hydraulic pump 3 is supplied to the other hydraulic device.
  • the discharge passage 16 is provided with a restriction 18.
  • the reference numeral 21 denotes a cylinder which has a piston 22, a large diameter pressure receiving chamber 23 and a small diameter pressure receiving chamber 24 defined at both sides of the piston 22, and the piston 22 is connected to a swash plate 20 of the variable hydraulic pump 2. Then, the swash plate 20 for varying a displacement of the variable hydraulic pump 2 is designed to vary an angle thereof by being pivotally tilted by a piston 22 of a swash plate control cylinder 21. The piston 22 of the cylinder 21 is moved in a displacement reducing direction by a pressurized fluid of the large diameter pressure receiving chamber 23 and moved in a displacement increasing direction by a pressurized fluid of the small diameter pressure receiving chamber 24 and a spring 25.
  • the large diameter pressure receiving chamber 23 is selectively connected to the tank 15 or the discharge passage 4, by a control valve 26 and the small diameter pressure receiving chamber 24 is connected to the discharge passage 4.
  • the control valve 26 has a first port 27 connected to the discharge passage 4 via the small diameter pressure receiving chamber 24 and a second port 28 connected to the large diameter pressure receiving chamber 23 and a tank port 29.
  • the control valve 26 is changed over to a drain position A to shut off the first port 27 and to communicate the second port 28 with the tank port 29 by a pressurized fluid of a first pressure receiving portion 30 and a pressurized fluid of a first auxiliary pressure receiving portion 31, and is changed over to a supply position B to communicate the first portion 27 with the second port 28 and to shut off the tank port 29 by the pressurized fluid of a second auxiliary pressure receiving portions 32 a pressurized fluid of a second auxiliary pressure receiving portion 33.
  • the first pressure receiving portion 30 is connected to an outlet side of a shuttle valve 19 detecting a higher pressure of the first circuit 9 and the second circuit 10 to be supplied with the outlet side pressure (load pressure) of the operation valve 5.
  • the second pressure receiving portion 32 is communicated with the discharge passage 4 via the small diameter pressure receiving chamber 24 to be supplied with the inlet side pressure (pump discharge pressure) of the operation valve 5.
  • the first auxiliary pressure receiving portion 31 is connected to a upstream side of the restriction 18, and the second auxiliary pressure receiving portion 33 is connected to a downstream side of the restriction 18.
  • a revolution speed of the engine 1 is controlled by feeding an engine speed command signal generated from an operation member 34, such as an accelerator pedal or the like, to a control governor 35 of the engine 1.
  • an operation member 34 such as an accelerator pedal or the like
  • the engine speed becomes low speed
  • a medium speed position b the engine speed becomes medium speed
  • the engine speed becomes high speed.
  • the control valve 26 is switched into the supply position B to pivoted the swash plate 4 in a direction to reduce the tilt angle thereof when the differential pressure between the inlet side pressure (pump discharge pressure) and the outlet side pressure (load pressure) of the operation valve 5 is greater than the set pressure, and is switched into the drain position A to tilt the swash plate 4 in a direction to increase the tilt angle thereof when the differential pressure is smaller than the set pressure to make the differential pressure between the inlet side pressure and the outlet side pressure of the operation valve 5 constant.
  • the discharge flow rate of the variable hydraulic pump 2 becomes a value corresponding to an opening degree (a communication area of the pump port 6 and the first or second actuator ports 7 or 8) of the operation valve 5.
  • a set differential pressure of the control valve 26 is varied depending upon a differential pressure between upstream and downstream of the restriction 18.
  • the differential pressure between upstream and downstream of the restriction 18 is proportional to a square of a discharge flow rate (engine speed) of the fixed displacement hydraulic pump 3.
  • the set differential pressure of the control valve 26 becomes small when the engine speed is low, and becomes large when the engine speed is high.
  • the discharge flow rate of the variable hydraulic pump 2 is reduced than that at the high speed to improve a fine operation ability.
  • the differential pressure between upstream and downstream of the restriction 18 is proportional to a square of the engine speed (discharge flow rate of the fixed displacement hydraulic pump 3) as shown in Fig. 2(a).
  • the set differential pressure between control valve 26 is linearly proportional to the differential pressure of the upstream and downstream of the restriction 18 as shown in Fig. 2(b).
  • the displacement of the variable hydraulic pump 2 is proportional to a square of the set differential pressure as shown in Fig. 2(c). Therefore, the discharge flow rate of the variable hydraulic pump 2 is linearly proportional to the engine speed as shown in Fig. 2(d).
  • control valve 26 Next, a particular construction of the control valve 26 will be explained.
  • a sleeve 42 is threadingly inserted into a sleeve bore 41 formed in a valve body 40, such as a housing or the like of the variable displacement pump 2.
  • the sleeve bore 41 is formed with a first inflow port 65, a flow out port 66, a control port 67, a pump pressure supply port 68 and a second inflow port 69.
  • the sleeve 42 is formed with a first port 43, a second port 44, a third port 45, a fourth port 46 and a fifth port 47.
  • a spool 48 is slidably disposed within a spool insertion bore 42a located at an axial center 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 small diameter portion 54 of a stationary piston 53 inserted in the spool insertion bore 42a is inserted to define a first pressure receiving chamber 55 (the second pressure receiving portion 32 of Fig. 1) and a second pressure receiving chamber 56 (the second auxiliary pressure receiving chamber 33 of Fig. 1).
  • the first pressure receiving chamber 55 is communicated with the second small diameter portion 51 through a fluid conduit 57 formed in the axial center portion of the spool 48.
  • a third pressure receiving chamber 58 is defined.
  • a cylindrical tip end portion 60 of the threaded rod 59 is engaged to define a fourth pressure receiving chamber 61. Furthermore, the threaded rod 59 is threadingly engaged with the sleeve 42 and fixed by tightening a lock nut 62. Then, in the axial center portion of the threaded rod 59, a bore 64 communicated with the fourth pressure receiving chamber 61 via the cylindrical tip end portion 60, is formed and extended from a piping joint portion 63 at the other end. Also, in the spring insertion hole 42b, the spring 49 is disposed between the other end of the spool 48 and the cylindrical tip end 60 of the threaded rod 59.
  • a pressure receiving diameter d 1 of the first pressure receiving chamber 55 and a pressure receiving diameter d 2 of the fourth pressure receiving chamber 61 are equal to each other.
  • the first port 43 is communicated with the second pressure receiving chamber 56 and the first inflow port 65.
  • the first inflow port 65 is connected to the downstream side of the restriction 18 shown in Fig. 1.
  • the second port 44 is connected to the flow out port 66 (the tank port 29 in Fig. 1).
  • the flow out port 66 is communicated with the tank 15 shown in Fig. 1.
  • the third port 45 is connected to a control port 67 (the second port 28 in Fig. 1).
  • the control port 67 is connected to the large diameter pressure receiving chamber 23.
  • the fourth port 46 is connected to a pump pressure supply port 68 (the first port 27 in Fig. 1).
  • the pump pressure supply port 68 is connected to the discharge passage 4 via the small diameter chamber 24.
  • the fifth port 47 is connected to the third pressure receiving chamber 58 (the first auxiliary pressure receiving portion 31 in Fig. 1) and a second inflow port 69.
  • the second inflow port 69 is connected to the upstream side of the restriction 18 shown in Fig. 1.
  • a not shown hose is connected to the piping joint portion 63. Through these, the outlet side pressure (load pressure) of the operation valve 5 is supplied to the fourth pressure receiving portion 61 (first pressure receiving portion 30 in Fig. 1).
  • a pump discharge pressure P 1 of the variable hydraulic pump 2 is supplied to the fourth port 46 through the pump pressure supply port 68, and supplied to the first pressure receiving chamber 55 via the second small diameter portion 51 and the fluid conduit 57 to thrust the spool 48 toward right.
  • the outlet side pressure (load pressure) P LS of the operation valve is supplied to the fourth pressure receiving chamber 61 to thrust the spool 48 toward left.
  • the second port 44 communicates with the third port 45 to establish communication of the control port 67 with the tank 15 via the flow out port 66 to place the control valve 26 at the drain position A in Fig. 1. Then, the pressurized fluid of the large diameter pressure receiving chamber 23 of the swash plate control valve 21 flows out, the displacement of the variable hydraulic pump 2 is increased, accordingly.
  • the spool 48 is moved toward right to be placed in a condition shown in Fig. 3 to block the communication between the second port 44 and the third port 45.
  • the communication between the control port 67 and the flow out port 66 is blocked.
  • the spool 48 is thrust toward right by the pressure of the downstream side of the restriction 18 acting in the second pressure receiving chamber 56 and thrust toward left by the pressure of the upstream side of the restriction 18 acting in the third pressure receiving chamber 58.
  • the set differential pressure is greater than that in the case set forth above.
  • D is a diameter of the spool 48
  • P 2 is the pressure at upstream side of the restriction 18
  • P 3 is the pressure at the downstream side of the restriction 18.
  • Fig. 4 shows the second embodiment of the displacement control system for the variable displacement type hydraulic pump according to the present invention. This is constructed by providing a first restriction 71 in a pilot circuit 70 connecting the downstream side of the restriction 18 in the discharge passage 16 of the fixed displacement hydraulic pump 3 and the second auxiliary pressure receiving portion 33 of the control valve 26, and connecting the downstream side of the first restriction 71 with the tank 15 through a drain circuit 73, and providing a second restriction 73 in the drain circuit 72.
  • the discharge passage 16 of the fixed displacement hydraulic pump 3 is connected to a swiveling hydraulic motor 76 via an auxiliary operation valve 75.
  • a swiveling hydraulic motor 76 is driven.
  • a ratio of lowering of pressure becomes a given ratio determined by the flow area of the first restriction 71 and the flow area of the second restriction 73.
  • the fixed displacement hydraulic pump 3 is constructed with a gear pump, for example.
  • the discharge pressure becomes high, internal leakage amount is increased to lower efficiency. Therefore, even at the same revolution speed, the discharge flow rate of the fixed displacement hydraulic pump 3 in high pressure is reduced than that in the low pressure.
  • the differential pressure (P 2 - P 3 ) between upstream and downstream of the restriction 18 becomes smaller. Therefore, upon starting up of the swiveling hydraulic motor 76, the differential pressure (P 2 - P) between upstream and downstream of the restriction 18 becomes smaller. Also, during steady revolution, the differential pressure (P 2 - P 3 ) between upstream and downstream of the restriction 18 becomes large.
  • the differential pressure between the pressure acting in the first auxiliary pressure receiving portion 31 of the control valve 26 and the pressure acting in the second auxiliary pressure receiving portion 33 is varied between that upon starting up of the swiveling hydraulic motor 76 and that during steady revolution to differentiate the discharge flow rate of the variable hydraulic motor 2.
  • the discharge pressure of the fixed displacement hydraulic pump 3 is 50 kg/cm 2 and the discharge flow rate is 20 l/min
  • the pressure P 3 at the downstream side of the restriction 18 is 40 kg/cm 2
  • the pressure P 4 in the second auxiliary pressure receiving portion 33 is 39.5 kg/cm 2 during steady revolution of the swiveling hydraulic motor 76
  • the differential pressure (P 2 - P 4 ) between the pressure P 2 acting in the first auxiliary pressure receiving portion 31 and the pressure P 4 acting in the second auxiliary pressure receiving portion 33 of the control valve 26 becomes 10 kg/cm 2 .
  • Fig. 5 shows the third embodiment of the displacement control system of the variable displacement type hydraulic pump according to the present invention.
  • the drain port 29 of the control valve 26 is selectively connected to one of the tank 15 and the discharge passage 4 by the switching valve 80 for an input torque control.
  • the switching valve 80 is changed over to a drain position C by the spring 81 and is changed over to a supply position D by the discharge pressure of the variable displacement pump 2 acting in the first pressure receiving portion 82, and an external pressure acting in the second pressure receiving portion 83. Furthermore, the spring 81 is associated with the piston 22 by a link 84.
  • the switching valve 80 is changed over to the supply position D.
  • the discharge pressure flows into the large diameter pressure receiving chamber 23 via the control valve 26. Therefore, the piston 22 is moved toward right to pivot the swash plate 20 to tilt in the direction of smaller displacement.
  • the mounting load of the spring 81 is increased via the link 84 to change over the switching valve 80 back to the drain position C.
  • variable hydraulic pump 2 the displacement of the variable hydraulic pump 2 is controlled so that an input torque (pump discharge pressure x displacement) becomes constant.
  • the discharge flow rate of the fixed displacement type hydraulic pump 3 is reduced.
  • the differential pressure between upstream and downstream of the restriction 18 becomes smaller to make the set differential pressure of the control valve 26 smaller.
  • the discharge flow rate of the fixed displacement type hydraulic pump 3 is increased.
  • the differential pressure between upstream and downstream of the restriction 18 becomes larger to make the set differential pressure of the control valve 26 larger.
  • the discharge flow rate of the variable displacement type hydraulic pump 2 is significantly smaller to improve the operability in fine motion.
  • the set differential pressure of the control valve 26 is varied by the differential pressure between upstream and downstream of the restriction 18 provided in the discharge passage 16 of the fixed displacement type hydraulic pump 3, the discharged pressurized fluid of the fixed displacement type hydraulic pump 3 does not flow out to the tank 15 and thus can be used effectively.
  • the differential pressure between upstream and downstream of the restriction 18 will not be varied even when the discharged pressurized fluid of the fixed displacement type hydraulic pump 3 is supplied to other hydraulic device.
  • the displacement control characteristics of the variable displacement type hydraulic pump 2 can be made constant.
  • the differential pressure between upstream and downstream of the restriction 18 is caused to make it possible to control the displacement of the variable displacement type hydraulic pump 2 with taking the engine speed into account.
  • the pressure P 4 acting in the second auxiliary pressure receiving portion 33 of the control valve 26 becomes a value corresponding to the pressure P 3 at downstream of the restriction 18 provided in the discharge passage 16 of the fixed displacement type hydraulic pump 3 lowered by a given ratio.
  • the pressure difference between the first auxiliary pressure receiving portion 31 and the second auxiliary pressure receiving portion 33 of the control valve 26 becomes substantially constant.
  • the set differential pressure of the control valve 26 can be constant to make the discharge flow rate of the variable displacement type hydraulic pump 2 can be substantially constant.

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)
EP96909349A 1995-04-12 1996-04-11 Regeleinrichtung für eine hydraulikpumpe mit variabler verdrängung Ceased EP0821167A4 (de)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
JP8669795 1995-04-12
JP86697/95 1995-04-12
JP214736/95 1995-08-23
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
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

Publications (2)

Publication Number Publication Date
EP0821167A1 true EP0821167A1 (de) 1998-01-28
EP0821167A4 EP0821167A4 (de) 1998-09-02

Family

ID=26427791

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96909349A Ceased EP0821167A4 (de) 1995-04-12 1996-04-11 Regeleinrichtung für eine hydraulikpumpe mit variabler verdrängung

Country Status (3)

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

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1106833A1 (de) * 1999-06-10 2001-06-13 Hitachi Construction Machinery Co., Ltd. Mengenregelventil einer kolbenmaschine mit variablem hub
WO2005038252A1 (de) * 2003-09-22 2005-04-28 Klaus Riedel Kombinationsschraube
US11486277B2 (en) 2021-02-26 2022-11-01 Deere & Company Work vehicle engine with split-circuit lubrication system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002048235A (ja) * 2000-08-02 2002-02-15 Komatsu Ltd 油圧ポンプの容量制御装置

Citations (2)

* 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
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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Publication number Priority date Publication date Assignee Title
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
US5101629A (en) * 1989-02-20 1992-04-07 Hitachi Construction Machinery Co., Ltd. Hydraulic circuit system for working machine
DE4115606A1 (de) * 1991-05-14 1992-11-19 Putzmeister Maschf Ueberlast-schutzeinrichtung fuer einen als brennkraftmaschine ausgebildeten antriebsmotor einer hauptpumpe eines hydraulischen druckversorgungsaggregats
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
JP3179596B2 (ja) * 1992-11-17 2001-06-25 日立建機株式会社 流量制御装置

Patent Citations (2)

* 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
JPH05172107A (ja) 1991-12-24 1993-07-09 Komatsu Ltd 可変油圧ポンプの容量制御装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO9632593A1

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1106833A1 (de) * 1999-06-10 2001-06-13 Hitachi Construction Machinery Co., Ltd. Mengenregelventil einer kolbenmaschine mit variablem hub
EP1106833A4 (de) * 1999-06-10 2011-03-16 Hitachi Construction Machinery Mengenregelventil einer kolbenmaschine mit variablem hub
WO2005038252A1 (de) * 2003-09-22 2005-04-28 Klaus Riedel Kombinationsschraube
US11486277B2 (en) 2021-02-26 2022-11-01 Deere & Company Work vehicle engine with split-circuit lubrication system

Also Published As

Publication number Publication date
JPH08338405A (ja) 1996-12-24
EP0821167A4 (de) 1998-09-02
WO1996032593A1 (fr) 1996-10-17

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