JPH08338405A - Capacity control device for variable displacement hydraulic pump - Google Patents
Capacity control device for variable displacement hydraulic pumpInfo
- Publication number
- JPH08338405A JPH08338405A JP7214736A JP21473695A JPH08338405A JP H08338405 A JPH08338405 A JP H08338405A JP 7214736 A JP7214736 A JP 7214736A JP 21473695 A JP21473695 A JP 21473695A JP H08338405 A JPH08338405 A JP H08338405A
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- pressure receiving
- hydraulic pump
- receiving portion
- receiving chamber
- 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.)
- Pending
Links
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
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
Description
【0001】[0001]
【発明の属する技術分野】本発明は、建設機械等のアク
チュエータに圧油を供給する油圧回路に用いられる可変
容量型油圧ポンプの容量を制御する装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling the displacement of a variable displacement hydraulic pump used in a hydraulic circuit that supplies pressure oil to an actuator of a construction machine or the like.
【0002】[0002]
【従来の技術】建設機械等のアクチュエータに圧油を供
給する油圧回路としては、油圧ポンプの吐出圧油を操作
弁によりアクチュエータに供給するものが知られ、この
油圧回路において中立位置の時にポンプポートを遮断す
るクローズドセンター型の操作弁とすると、操作弁が中
立位置の時に油圧ポンプの吐出圧油が行き止りとなって
高圧となるので、その油圧ポンプを駆動するエンジンの
駆動馬力消費が大となる。2. Description of the Related Art As a hydraulic circuit for supplying pressure oil to an actuator of a construction machine or the like, there is known a hydraulic circuit for supplying pressure oil discharged from a hydraulic pump to an actuator by an operation valve. With a closed center type operation valve that shuts off the oil, when the operation valve is in the neutral position, the discharge pressure oil of the hydraulic pump becomes a dead end and becomes high pressure, so the driving horsepower consumption of the engine that drives the hydraulic pump is large. Become.
【0003】このことを解消する油圧回路としては、例
えば実開平5−86003号公報に示すように、油圧ポ
ンプを可変容量型油圧ポンプ(以下可変油圧ポンプとい
う)とし、その可変油圧ポンプの容量(1回転当り吐出
量)を操作弁の入口側圧力(ポンプ吐出圧)と出口側圧
力(負荷圧)との差圧が大きい時には小容量、前記差圧
が小さい時には大容量として差圧が一定となるように制
御し、可変油圧ポンプの吐出流量(容量×単位時間当り
回転数)を操作弁の開度(ポンプポートとアクチュエー
タポートの連通面積)に見合う値としたものが知られて
いる。As a hydraulic circuit for solving this, for example, as shown in Japanese Utility Model Laid-Open No. 5-86003, the hydraulic pump is a variable displacement hydraulic pump (hereinafter referred to as variable hydraulic pump), and the capacity of the variable hydraulic pump ( The discharge amount per one rotation is set to a small capacity when the differential pressure between the inlet side pressure (pump discharge pressure) and the outlet side pressure (load pressure) of the operating valve is large, and a large volume when the differential pressure is small to keep the differential pressure constant. It is known that the discharge flow rate (capacity × rotation number per unit time) of the variable hydraulic pump is set to a value commensurate with the opening degree of the operation valve (communication area of the pump port and the actuator port).
【0004】前述の油圧回路において、可変油圧ポンプ
の吐出流量は容量が同一であってもエンジン回転数が低
速の時には少なく高速の時には多くなり、操作弁の開度
が同一でもその入口側圧力と出口側圧力との差圧が異な
るから、操作弁の開度が同一でもエンジン回転数が低速
の時には可変油圧ポンプの容量を大として吐出流量を開
度に見合う値とし、高速の時には可変油圧ポンプの容量
を小として吐出流量を開度に見合う値とする。In the above-mentioned hydraulic circuit, the discharge flow rate of the variable hydraulic pump is small when the engine speed is low and increases when the engine speed is high even if the displacement is the same. Since the pressure difference with the outlet side pressure is different, even if the opening of the operating valve is the same, when the engine speed is low, the capacity of the variable hydraulic pump is large and the discharge flow rate is set to a value commensurate with the opening. The discharge flow rate is set to a value commensurate with the degree of opening by setting the capacity of the valve to be small.
【0005】このために、アクチュエータへの供給流量
を減少してアクチュエータを微少作動する微少操作した
い時にエンジン回転数を低下しても前述の動作によって
可変油圧ポンプの容量が大となり、可変油圧ポンプの吐
出流量が増大としてしまうので、前述の微少操作ができ
ない。For this reason, even if the engine rotational speed is lowered when it is desired to perform a minute operation in which the actuator is slightly operated by reducing the flow rate supplied to the actuator, the above-mentioned operation increases the capacity of the variable hydraulic pump, and the variable hydraulic pump has a large capacity. Since the discharge flow rate increases, the above-mentioned minute operation cannot be performed.
【0006】このようなことから、前述の実開平5−8
6003号公報に示す油圧回路には、可変油圧ポンプを
駆動するエンジンで固定容量型油圧ポンプ(以下固定油
圧ポンプという)を駆動し、その固定油圧ポンプの吐出
路に絞りとリリーフ弁を備えたドレーン回路を接続し、
その吐出路における接続部より固定油圧ポンプ寄りの圧
力を検出し、その検出圧力によっても可変油圧ポンプの
容量を制御するようにしている。From the above, the above-mentioned actual Kaihei 5-8
In the hydraulic circuit shown in Japanese Patent No. 6003, a fixed displacement hydraulic pump (hereinafter referred to as a fixed hydraulic pump) is driven by an engine that drives a variable hydraulic pump, and a drain and a relief valve are provided in a discharge passage of the fixed hydraulic pump. Connect the circuit,
The pressure closer to the fixed hydraulic pump than the connecting portion in the discharge passage is detected, and the displacement of the variable hydraulic pump is also controlled by the detected pressure.
【0007】このようにすれば、前記検出圧力はエンジ
ン回転数に見合う値となるので、ポンプ吐出圧と負荷圧
の差圧がエンジン回転数に見合う値となり、可変油圧ポ
ンプの容量をエンジン回転数を加味して制御できる。With this configuration, the detected pressure has a value commensurate with the engine speed, so that the differential pressure between the pump discharge pressure and the load pressure has a value commensurate with the engine speed, and the displacement of the variable hydraulic pump is changed to the engine speed. Can be added to control.
【0008】[0008]
【発明が解決しようとする課題】しかしながら、前述の
構成であると固定油圧ポンプの吐出圧油の一部を絞り、
リリーフ弁よりタンクに流出しているので、その吐出圧
油を有効利用できないし、その吐出圧油を他の油圧機器
に供給した場合にはタンクに流出する流量が減少して絞
り前後の差圧が変化するので、検出圧力が異なって可変
油圧ポンプの容量制御特性が変化してしまう。また、エ
ンジン回転数が極めて低速の時には固定油圧ポンプの吐
出流量が少なくリリーフ弁のセット圧まで圧力上昇しな
いことがあり、その場合には可変油圧ポンプの容量をエ
ンジン回転数を加味して制御できない。However, with the above-mentioned configuration, a part of the discharge pressure oil of the fixed hydraulic pump is throttled,
Since the pressure oil is discharged from the relief valve to the tank, the discharged pressure oil cannot be used effectively, and when the discharged pressure oil is supplied to other hydraulic equipment, the flow rate to the tank decreases and the differential pressure before and after the throttle is reduced. Changes, the detected pressure differs and the displacement control characteristic of the variable hydraulic pump changes. Also, when the engine speed is extremely low, the discharge flow rate of the fixed hydraulic pump is small and the pressure may not rise to the set pressure of the relief valve. In that case, the capacity of the variable hydraulic pump cannot be controlled in consideration of the engine speed. .
【0009】そこで、本発明は前述の課題を解決できる
ようにした可変容量型油圧ポンプの容量制御装置を提供
することを目的とする。SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a displacement control device for a variable displacement hydraulic pump that can solve the above-mentioned problems.
【0010】[0010]
【課題を解決するための手段】第1の発明は、可変容量
型油圧ポンプ2の容量を制御するシリンダ21と、この
シリンダ21にポンプ吐出圧を供給制御する制御弁26
と、前記可変容量型油圧ポンプ2と同一のエンジン1で
駆動される固定容量型油圧ポンプ3と、その吐出路16
に設けた絞り18を備え、前記制御弁26を、ポンプ吐
出圧と負荷圧の差圧と差圧セット力との大小関係によっ
て切換作動されて前記差圧を差圧セット力に見合う一定
の値とし、かつ前記絞18前後の差圧が大きい時には差
圧セット力を大きく、小さい時には差圧セット力を小さ
くするものとした可変容量型油圧ポンプの容量制御装置
である。第2の発明は、可変容量型油圧ポンプ2の容量
を制御するシリンダ21と、このシリンダ21にポンプ
吐出圧を供給制御する制御弁26と、前記可変容量型油
圧ポンプ2と同一のエンジン1で駆動される固定容量型
油圧ポンプ3と、その吐出路16に設けた絞り18を備
え、前記シリンダ21を大径受圧室23に圧油が供給さ
れると容量小方向に移動し、その大径受圧室23がドレ
ーンに連通すると容量大方向に移動するものとし、前記
制御弁26を、第1受圧部30と第1補助受圧部31の
圧力で大径受圧室23をドレーンに連通するドレーン位
置Aとなり、第2受圧部32と第2補助受圧部33の圧
油で大径受圧室23にポンプ吐出圧を供給する供給位置
Bとなるものとし、前記第1受圧部30に負荷圧を供給
し、第2受圧部32にポンプ吐出圧を供給し、第1補助
受圧部31に絞り18上流側圧力を供給し、第2補助受
圧部33に絞り18下流側に接続したドレーン路におけ
る第1絞りと第2絞りとの中間の圧力を供給した可変容
量型油圧ポンプの容量制御装置である。A first invention is a cylinder 21 for controlling the displacement of a variable displacement hydraulic pump 2, and a control valve 26 for controlling the pump discharge pressure to the cylinder 21.
A fixed displacement hydraulic pump 3 driven by the same engine 1 as the variable displacement hydraulic pump 2 and its discharge passage 16
The control valve 26 is switched by the magnitude relationship between the differential pressure between the pump discharge pressure and the load pressure and the differential pressure setting force to adjust the differential pressure to a constant value corresponding to the differential pressure setting force. The capacity control device for the variable displacement hydraulic pump is such that the differential pressure setting force is large when the differential pressure before and after the throttle 18 is large, and is small when the differential pressure is small. A second aspect of the invention is a cylinder 21 that controls the displacement of the variable displacement hydraulic pump 2, a control valve 26 that controls the supply of pump discharge pressure to the cylinder 21, and an engine 1 that is the same as the variable displacement hydraulic pump 2. A fixed displacement hydraulic pump 3 to be driven and a throttle 18 provided in the discharge passage 16 are provided, and when the pressure oil is supplied to the large diameter pressure receiving chamber 23, the cylinder 21 moves in the small capacity direction, and the large diameter It is assumed that when the pressure receiving chamber 23 communicates with the drain, it moves in the large capacity direction, and the control valve 26 is moved to the drain position where the large diameter pressure receiving chamber 23 communicates with the drain by the pressure of the first pressure receiving portion 30 and the first auxiliary pressure receiving portion 31. A, and the supply position B for supplying the pump discharge pressure to the large-diameter pressure receiving chamber 23 by the pressure oil of the second pressure receiving portion 32 and the second auxiliary pressure receiving portion 33, and supplying the load pressure to the first pressure receiving portion 30. The second pressure receiving portion 32 The discharge pressure is supplied, the upstream pressure of the throttle 18 is supplied to the first auxiliary pressure receiving portion 31, and the second auxiliary pressure receiving portion 33 is provided with an intermediate pressure between the first throttle and the second throttle in the drain path connected to the downstream side of the throttle 18. It is a displacement control device for a variable displacement hydraulic pump that supplies pressure.
【0011】[0011]
【作 用】第1の発明によれば、エンジン1の回転数
が低速の時には固定容量型油圧ポンプ3の吐出流量が少
なく絞り18前後の差圧が小さくなって制御弁26の差
圧セット力が小さくなり、エンジン1の回転数が高速の
時には固定容量型油圧ポンプその吐出流量が多く絞り1
8前後の差圧が大きくなって制御弁26の差圧セット力
が大きくなる。これにより、エンジン1が低速回転数の
時に可変容量型油圧ポンプ2の吐出流量が著しく少なく
なる。第2の発明によれば、制御弁26の第2補助受圧
部33に作用する圧力P4 は、固定容量型油圧ポンプ3
の吐出路16に設けた絞り18の下流側圧力P3 を一定
比率で減圧した値となり、エンジン1の回転数が一定で
固定容量型油圧ポンプ3の吐出圧による効率変化に伴な
い吐出流量が変化した場合でも制御弁26の第1補助受
圧部31と第2補助受圧部33との圧力差がほぼ同一と
なるから、固定容量型油圧ポンプ3の回転速度が同一
で、その吐出圧が高圧、低圧に変化した場合に制御弁2
6の差圧セット力がほぼ同一となり、可変容量型油圧ポ
ンプ2の吐出流量がほぼ同一となる。[Operation] According to the first aspect of the invention, when the rotational speed of the engine 1 is low, the discharge flow rate of the fixed displacement hydraulic pump 3 is small and the differential pressure before and after the throttle 18 becomes small, so that the differential pressure setting force of the control valve 26 is reduced. Becomes smaller and the rotational speed of the engine 1 is high, the fixed displacement hydraulic pump has a large discharge flow rate and the throttle 1
The differential pressure before and after 8 increases, and the differential pressure setting force of the control valve 26 increases. As a result, the discharge flow rate of the variable displacement hydraulic pump 2 is significantly reduced when the engine 1 is rotating at a low speed. According to the second invention, the pressure P 4 acting on the second auxiliary pressure receiving portion 33 of the control valve 26 is the fixed displacement hydraulic pump 3
Is a value obtained by reducing the downstream side pressure P 3 of the throttle 18 provided in the discharge passage 16 at a constant ratio, and the discharge flow rate due to the efficiency change due to the discharge pressure of the fixed displacement hydraulic pump 3 with the engine 1 being at a constant rotation speed. Even if there is a change, 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 the same, so the rotational speed of the fixed displacement hydraulic pump 3 is the same, and the discharge pressure thereof is high. , Control valve 2 when changing to low pressure
The differential pressure setting force of 6 becomes almost the same, and the discharge flow rate of the variable displacement hydraulic pump 2 becomes almost the same.
【0012】[0012]
【実 施 例】図1に示すように、エンジン1で可変容
量型油圧ポンプ2(以下可変油圧ポンプ2という)と固
定容量型油圧ポンプ3(以下固定油圧ポンプ3という)
を駆動し、その可変油圧ポンプ2の吐出路4は操作弁5
のポンプポート6に接続し、その操作弁5の第1・第2
アクチュエータポート7,8は第1・第2回路9,10
でアクチュエータ11の第1室12、第2室13に接続
され、タンクポート14はタンク15に接続してある。[Examples] As shown in FIG. 1, an engine 1 includes a variable displacement hydraulic pump 2 (hereinafter referred to as variable hydraulic pump 2) and a fixed displacement hydraulic pump 3 (hereinafter referred to as fixed hydraulic pump 3).
And the discharge passage 4 of the variable hydraulic pump 2 drives the operation valve 5
Of the operating valve 5 connected to the pump port 6 of the
The actuator ports 7 and 8 are the first and second circuits 9 and 10.
Is connected to the first chamber 12 and the second chamber 13 of the actuator 11, and the tank port 14 is connected to the tank 15.
【0013】前記固定油圧ポンプ3の吐出路16は油圧
パイロット弁17の入口側に接続し、その油圧パイロッ
ト弁17を操作することで他の油圧機器に固定油圧ポン
プ3の吐出流量を供給し、前記吐出路16には絞り18
が設けてある。The discharge passage 16 of the fixed hydraulic pump 3 is connected to the inlet side of the hydraulic pilot valve 17, and the hydraulic pilot valve 17 is operated to supply the discharge flow rate of the fixed hydraulic pump 3 to other hydraulic equipment. A diaphragm 18 is provided in the discharge passage 16.
Is provided.
【0014】前記可変油圧ポンプ2の容量を制御する斜
板20はシリンダ21のピストン22で傾転制御され、
そのシリンダ21のピストン22は大径受圧室23の圧
油で容量小方向に移動し、小径受圧室24の圧油とバネ
25で容量大方向に移動する。The swash plate 20 for controlling the displacement of the variable hydraulic pump 2 is tilt-controlled by a piston 22 of a cylinder 21,
The piston 22 of the cylinder 21 moves in the small capacity direction by the pressure oil in the large diameter pressure receiving chamber 23, and moves in the large capacity direction by the pressure oil in the small diameter pressure receiving chamber 24 and the spring 25.
【0015】前記大径受圧室23は制御弁26でタンク
15と吐出路4に接続制御され、小径受圧室24は吐出
路4に接続している。The large-diameter pressure receiving chamber 23 is connected and controlled by the control valve 26 to the tank 15 and the discharge passage 4, and the small-diameter pressure receiving chamber 24 is connected to the discharge passage 4.
【0016】前記制御弁26は吐出路4に接続した第1
ポート27と大径受圧室23に接続した第2ポート28
とタンクポート29を有し、第1受圧部30の圧油と第
1補助受圧部31の圧油により第1ポート27を遮断
し、かつ第2ポート28をタンクポート29に連通する
ドレーン位置Aに押され、第2受圧部32の圧油と第2
補助受圧部33の圧油により第1ポート27と第2ポー
ト28を連通し、かつタンクポート29を遮断する供給
位置Bに押される。The control valve 26 is a first valve connected to the discharge passage 4.
Second port 28 connected to port 27 and large diameter pressure receiving chamber 23
A drain position A in which the first port 27 is shut off by the pressure oil of the first pressure receiving portion 30 and the pressure oil of the first auxiliary pressure receiving portion 31 and the second port 28 communicates with the tank port 29. Is pushed by the pressure oil of the second pressure receiving portion 32 and the second pressure receiving portion 32.
The pressure oil of the auxiliary pressure receiving portion 33 pushes the supply port B to connect the first port 27 and the second port 28 and to block the tank port 29.
【0017】前記第1受圧部30は第1回路9と第2回
路10の高い方の圧力を検出するシャトル弁34の出口
側に接続して操作弁5の出口側圧力(負荷圧)が供給さ
れ、第2受圧部32は吐出路4に連通して操作弁5の入
口側圧力(ポンプ吐出圧)が供給され、第1補助受圧部
31は絞り18の上流側に接続し、第2補助受圧部33
は絞り18の下流側に接続する。The first pressure receiving portion 30 is connected to the outlet side of the shuttle valve 34 for detecting the higher pressure of the first circuit 9 and the second circuit 10, and the outlet side pressure (load pressure) of the operating valve 5 is supplied. Then, the second pressure receiving portion 32 is connected to the discharge passage 4 and the inlet side pressure (pump discharge pressure) of the operation valve 5 is supplied, and the first auxiliary pressure receiving portion 31 is connected to the upstream side of the throttle 18, and the second auxiliary pressure receiving portion 31 is connected. Pressure receiving part 33
Is connected to the downstream side of the diaphragm 18.
【0018】前記エンジン1の回転数はアクセルペダル
等の操作部材34よりの回転数指令をコントロールガバ
ナ35に送って制御される。例えば操作部材34を低速
位置aとすると低速回転、中速位置bとすると中速回
転、高速位置cとすると高速回転となる。The rotation speed of the engine 1 is controlled by sending a rotation speed command from an operating member 34 such as an accelerator pedal to a control governor 35. For example, when the operating member 34 is at the low speed position a, it rotates at low speed, when it is at the medium speed position b, it rotates at medium speed, and when it is at the high speed position c, it rotates at high speed.
【0019】次に作動を説明する。前記制御弁26は操
作弁5の入口側圧力(ポンプ吐出圧)と出口側圧力(負
荷圧)の差圧が差圧セット力より大きい時には供給位置
Bに切換って斜板4を傾転角度小方向に傾転し、前記差
圧が差圧セット力より小さい時にはドレーン位置Aに切
換って斜板4を傾転角度大方向に傾転して操作弁5の入
口側圧力と出口側圧力の差圧を一定とし、可変油圧ポン
プ2の吐出流量を操作弁5の開度(ポンプポート6と第
1又は第2アクチュエータポート7,8の連通面積)に
見合う値とし、制御弁26の差圧セット力は絞り18前
後の差圧によって可変となり、その絞り18前後の差圧
は固定油圧ポンプ3の吐出流量(エンジン回転数)の2
乗に比例する。Next, the operation will be described. When the differential pressure between the inlet side pressure (pump discharge pressure) and the outlet side pressure (load pressure) of the operating valve 5 is larger than the differential pressure setting force, the control valve 26 switches to the supply position B to tilt the swash plate 4 at a tilt angle. When the differential pressure is tilted in a small direction and the differential pressure is smaller than the differential pressure setting force, it is switched to the drain position A and the swash plate 4 is tilted in the large tilt angle direction so that the inlet side pressure and the outlet side pressure of the operation valve 5 are changed. Of the control valve 26, the discharge flow rate of the variable hydraulic pump 2 is set to a value commensurate with the opening degree of the operation valve 5 (the communication area between the pump port 6 and the first or second actuator port 7, 8). The pressure setting force is variable depending on the differential pressure before and after the throttle 18, and the differential pressure before and after the throttle 18 is 2 times the discharge flow rate (engine speed) of the fixed hydraulic pump 3.
Proportional to the square.
【0020】このようであるから、制御弁26の差圧セ
ット力はエンジン回転数が低速の時には小さく、高速の
時には大きくなり、エンジン回転数を低速として微少操
作する時に可変油圧ポンプ2の吐出流量が高速時よりも
減少して微少操作性が向上する。Because of this, the differential pressure setting force of the control valve 26 is small when the engine speed is low and is large when the engine speed is high, and the discharge flow rate of the variable hydraulic pump 2 is small when the engine speed is low and the operation is minute. However, it is less than at high speed, and the micro operability is improved.
【0021】つまり、絞り18前後の差圧は図2の
(a)のようにエンジン回転数(固定油圧ポンプの吐出
流量)の2乗に比例し、制御弁26の差圧セット力は図
2の(b)のように絞り18前後の差圧に一次比例し、
可変油圧ポンプの容量は図2の(c)のように差圧セッ
ト力の2乗に比例するので、可変油圧ポンプの吐出流量
は図2の(d)に示すようにエンジン回転数に一次比例
する。That is, the differential pressure before and after the throttle 18 is proportional to the square of the engine speed (the discharge flow rate of the fixed hydraulic pump) as shown in FIG. 2A, and the differential pressure setting force of the control valve 26 is shown in FIG. (B), it is linearly proportional to the differential pressure before and after the throttle 18,
Since the capacity of the variable hydraulic pump is proportional to the square of the differential pressure setting force as shown in FIG. 2 (c), the discharge flow rate of the variable hydraulic pump is linearly proportional to the engine speed as shown in FIG. 2 (d). To do.
【0022】次に制御弁26の具体構造を説明する。図
3に示すように、可変油圧ポンプ2のハウジング等の弁
本体40のスリーブ孔41にスリーブ42が嵌挿され、
そのスリーブ42には第1のポート43、第2のポート
44、第3のポート45、第4のポート46、第5のポ
ート47が形成され、そのスリーブ42のスプール嵌挿
孔42a内にはスプール48が嵌挿され、スプリング挿
入孔42bにはスプリング49が挿入して設けてある。Next, the specific structure of the control valve 26 will be described. As shown in FIG. 3, the sleeve 42 is fitted and inserted into the sleeve hole 41 of the valve body 40 such as the housing of the variable hydraulic pump 2,
A first port 43, a second port 44, a third port 45, a fourth port 46, and a fifth port 47 are formed in the sleeve 42, and the spool fitting hole 42a of the sleeve 42 is provided in the sleeve 42. The spool 48 is fitted and the spring 49 is inserted in the spring insertion hole 42b.
【0023】前記スプール48は第1小径部50と第2
小径部51と第3小径部52を有し、一端部軸心にはス
プール嵌挿孔42aに嵌挿した固定ピストン53の小径
部54が嵌合されて第1受圧室55と第2受圧室56を
形成し、その第1受圧室55はスプール48に形成した
油孔57で第2小径部51に開口し、前記第3小径部5
2がスプリング挿入孔42aに突出して第3受圧室58
を形成している。The spool 48 has a first small diameter portion 50 and a second small diameter portion 50.
The small diameter portion 51 has a small diameter portion 51 and a third small diameter portion 52, and the small diameter portion 54 of the fixed piston 53 fitted into the spool fitting hole 42a is fitted to the shaft center of the one end portion to form the first pressure receiving chamber 55 and the second pressure receiving chamber 55. 56, the first pressure receiving chamber 55 is opened in the second small diameter portion 51 by an oil hole 57 formed in the spool 48, and the third small diameter portion 5 is formed.
2 protrudes into the spring insertion hole 42a and the third pressure receiving chamber 58
Is formed.
【0024】前記スリーブ42のスプリング挿入孔42
bにはネジ杆59の先端円筒部60が嵌合して第4受圧
室61を形成し、ネジ杆59をスリーブ42に螺合して
ロックナット62で固定され、そのネジ杆59の他端配
管継手部63より第4受圧室61に開口した孔64が形
成してある。The spring insertion hole 42 of the sleeve 42
The tip cylindrical portion 60 of the screw rod 59 is fitted in b to form a fourth pressure receiving chamber 61, the screw rod 59 is screwed into the sleeve 42 and fixed by a lock nut 62, and the other end of the screw rod 59 is fixed. A hole 64 opening from the pipe joint portion 63 to the fourth pressure receiving chamber 61 is formed.
【0025】前記第1のポート43は第2受圧室56と
第1流入ポート65に連通し、その第1流入ポート65
は図1の絞り18の下流側に接続し、第2のポート44
は流出ポート66に接続し、その流出ポート66はタン
クに連通し、第3のポート45は制御ポート67に接続
し、第4のポート46はポンプ圧供給ポート68に接続
し、第5のポート47は第2流入ポート69に接続し、
その第2流入ポート69は図1の絞り18の上流側に接
続し、前記他端配管継手部63にはホースが接続されて
第4受圧室61に操作弁出口側圧力(負荷圧)が供給さ
れる。The first port 43 communicates with the second pressure receiving chamber 56 and the first inflow port 65, and the first inflow port 65 thereof.
Is connected to the downstream side of the throttle 18 in FIG.
Is connected to the outflow port 66, the outflow port 66 communicates with the tank, the third port 45 is connected to the control port 67, the fourth port 46 is connected to the pump pressure supply port 68, and the fifth port. 47 is connected to the second inflow port 69,
The second inflow port 69 is connected to the upstream side of the throttle 18 in FIG. 1, and a hose is connected to the other end pipe joint portion 63 to supply the operating valve outlet side pressure (load pressure) to the fourth pressure receiving chamber 61. To be done.
【0026】次に作動を説明する。可変油圧ポンプ2の
ポンプ吐出圧P1 はポンプ圧供給ポート68より第4の
ポート46に供給されると共に、第2小径部51、油孔
57より第1受圧室55に供給されスプール48を右方
に押し、操作弁出力側圧力(負荷圧)PLSは第4受圧室
61に供給されてスプール48を左方に押す。Next, the operation will be described. The pump discharge pressure P 1 of the variable hydraulic pump 2 is supplied to the fourth port 46 from the pump pressure supply port 68 and to the first pressure receiving chamber 55 through the second small diameter portion 51 and the oil hole 57, and the spool 48 is moved to the right. The control valve output side pressure (load pressure) P LS is supplied to the fourth pressure receiving chamber 61 and pushes the spool 48 to the left.
【0027】ここで、ポンプ吐出圧P1 と負荷圧PLSの
差圧がゼロ(P1 =PLS)の時、すなわち操作弁開度大
の時には第1受圧室55の受圧径d1 と第4受圧室61
の受圧径d2 が等しいので、スプール48はスプリング
49で図3で左方へ押される。Here, when the differential pressure between the pump discharge pressure P 1 and the load pressure P LS is zero (P 1 = P LS ), that is, when the operation valve opening is large, the pressure receiving diameter d 1 of the first pressure receiving chamber 55 becomes Fourth pressure receiving chamber 61
Since the pressure receiving diameters d 2 are equal to each other, the spool 48 is pushed leftward in FIG. 3 by the spring 49.
【0028】これにより、スプール48の第1小径部5
0で第2のポート44と第3のポート45が連通し、制
御ポート67が流出ポート66を経てタンクに連通して
図1における制御弁26がドレーン位置Aとなった状態
となるので可変油圧ポンプ2の容量は増大する。As a result, the first small diameter portion 5 of the spool 48 is
At 0, the second port 44 and the third port 45 communicate with each other, the control port 67 communicates with the tank through the outflow port 66, and the control valve 26 in FIG. The capacity of the pump 2 increases.
【0029】可変油圧ポンプ2の容量が大となって吐出
流量が増加すると操作弁5のポンプポート6より第1又
は第2アクチュエータポート7,8に流れる流量が増大
し、操作弁5の開度が前述と同一のままであると操作弁
圧力損失が大となってポンプ吐出圧P1 と負荷圧PLSの
差圧が大となる。When the displacement of the variable hydraulic pump 2 becomes large and the discharge flow rate increases, the flow rate of the flow from the pump port 6 of the operation valve 5 to the first or second actuator port 7, 8 increases, and the opening degree of the operation valve 5 increases. If the above condition remains the same as above, the pressure loss of the operating valve becomes large and the differential pressure between the pump discharge pressure P 1 and the load pressure P LS becomes large.
【0030】これにより、スプール48に作用する力
は、 π/4d1 2 ×P1 −π/4d2 2 ×PLS>0 となり、その力がスプリング49の取付荷重より大きく
なるとスプール48は右方に移動して図3の状態となっ
て第2のポート44と第3のポート45を遮断して制御
ポート67と流出ポート66を遮断される。As a result, the force acting on the spool 48 becomes π / 4d 1 2 × P 1 −π / 4d 2 2 × P LS > 0, and when the force becomes larger than the mounting load of the spring 49, the spool 48 moves to the right. Then, the second port 44 and the third port 45 are shut off, and the control port 67 and the outflow port 66 are shut off.
【0031】また、前述のようにd1 =d2 であるから
π/4d2 2 ×△PLS(差圧)とスプリング49の初期
取付荷重が等しいとスプール48は図3の位置で常に停
止しており、よってポンプの吐出圧P1 と負荷圧PLSの
差圧△PLSは常に一定に維持され、その差圧(差圧セッ
ト力)はスプリング49の初期取付荷重によって決定さ
れる。Further, since d 1 = d 2 as described above, if π / 4d 2 2 × ΔP LS (differential pressure) and the initial mounting load of the spring 49 are equal, the spool 48 always stops at the position shown in FIG. and are, thus the differential pressure △ P LS of the discharge pressure P 1 and the load pressure P LS pump is always kept constant, the differential pressure (differential pressure set force) is determined by the initial mounting load of the spring 49.
【0032】また、前記スプール48は第2の受圧室5
6に作用する絞り18下流側圧力で右方に押され、第3
の受圧室58に作用する絞り18上流側圧力で左方に押
されるので、スプール48は絞り18前後の差圧によっ
て左方に押され、差圧セット力は前述の場合よりも大き
くなる。Further, the spool 48 is the second pressure receiving chamber 5
6 is pushed to the right by the pressure on the downstream side of the throttle 18 acting on
Since the pressure on the upstream side of the throttle 18 acting on the pressure receiving chamber 58 is pushed to the left, the spool 48 is pushed to the left due to the differential pressure before and after the throttle 18, and the differential pressure setting force becomes larger than that in the case described above.
【0033】つまり、スプール48が図3の位置で停止
する時の条件はπ/4d2 2 ×△PLS=スプリング49
の取付荷重+π/4(D2 −d1 2 )×(P2 −P3 )
となる。ただしDはスプール48の径、P2 は絞り18
上流側圧力、P3 は絞り18下流圧力である。That is, the condition for stopping the spool 48 at the position shown in FIG. 3 is π / 4d 2 2 × ΔP LS = spring 49
Mounting load of + π / 4 (D 2 -d 1 2) × (P 2 -P 3)
Becomes However, D is the diameter of the spool 48, P 2 is the diaphragm 18
The upstream pressure, P 3 is the downstream pressure of the throttle 18.
【0034】前述の条件において設定回転数にて所望の
差圧△PLSにセットされれば、エンジン回転数を低速と
した場合には固定油圧ポンプ3の吐出流量が減少して絞
り18前後の差圧(P2 −P3 )が小さくなり差圧セッ
ト力が低下し、スプール48は右方に移動して第3のポ
ート45と第4のポート46が連通してポンプ吐出圧が
制御ポート67に流れて図1の制御弁26が供給位置B
となった状態となり、それにより斜板20が容量小方向
に傾転して可変油圧ポンプ2の容量が減少し、吐出流量
が高速時よりも著しく減少する。If the desired differential pressure ΔP LS is set at the set rotation speed under the above-mentioned conditions, the discharge flow rate of the fixed hydraulic pump 3 decreases and the throttle valve before and after the throttle 18 is reduced when the engine rotation speed is low. differential pressure (P 2 -P 3) is differential pressure set force is reduced smaller, the spool 48 is moved to the right the third port 45 and fourth port 46 communicates with the pump discharge pressure control port 67, the control valve 26 of FIG.
In this state, the swash plate 20 tilts in the small capacity direction, the capacity of the variable hydraulic pump 2 is reduced, and the discharge flow rate is significantly reduced as compared with the high speed state.
【0035】図4は第2実施例を示し、固定油圧ポンプ
3の吐出路16における絞り18の下流側と制御弁26
の第2補助受圧部33を接続するパイロット回路70に
第1絞り71を設け、この第1絞り71より下流側をド
レーン回路72でタンク15に接続し、そのドレーン回
路72に第2絞り73を設けてある。FIG. 4 shows a second embodiment, in which the discharge passage 16 of the fixed hydraulic pump 3 is downstream of the throttle 18 and the control valve 26.
The first throttle 71 is provided in the pilot circuit 70 that connects the second auxiliary pressure receiving portion 33, the downstream side of the first throttle 71 is connected to the tank 15 by the drain circuit 72, and the second throttle 73 is connected to the drain circuit 72. It is provided.
【0036】前記固定油圧ポンプ3の吐出路16は補助
操作弁75で旋回油圧モータ76に接続制御され、その
補助操作弁75を供給位置として旋回油圧モータ26を
駆動するようにしてある。The discharge passage 16 of the fixed hydraulic pump 3 is connected to a swing hydraulic motor 76 by an auxiliary operating valve 75, and the swing hydraulic motor 26 is driven with the auxiliary operating valve 75 as a supply position.
【0037】次に作動を説明する。パイロット回路70
に第1絞り71を設けると共に、その第1絞り71の下
流側を第2絞り73を経てタンク15に接続したことに
より、制御弁26の第2補助受圧部33に作用する圧力
P4 は絞り18の下流側圧力P3 よりも第1絞り71を
通過する際に圧力降下するので、P3 >P4 となる。Next, the operation will be described. Pilot circuit 70
By providing the first throttle 71 on the downstream side and connecting the downstream side of the first throttle 71 to the tank 15 via the second throttle 73, the pressure P 4 acting on the second auxiliary pressure receiving portion 33 of the control valve 26 is reduced. Since the pressure drops when passing through the first throttle 71 than the downstream side pressure P 3 of 18, P 3 > P 4 .
【0038】前記の圧力降下は第1絞り71の流通面積
と第2絞り73の流通面積によって決定される一定の比
率となる。The pressure drop has a constant ratio determined by the flow area of the first throttle 71 and the flow area of the second throttle 73.
【0039】補助操作弁75を供給位置として固定油圧
ポンプ3の吐出圧油を旋回油圧モータ76に供給して駆
動する時に、その旋回油圧モータ76の起動トルクが大
であるから、起動時には固定油圧ポンプ3の吐出圧が著
しく高圧となり、定常旋回時には固定油圧ポンプ3の吐
出圧が低圧となる。When the auxiliary hydraulic valve 75 is used as the supply position to supply the hydraulic fluid discharged from the fixed hydraulic pump 3 to the swing hydraulic motor 76 to drive it, the swing torque of the swing hydraulic motor 76 is large. The discharge pressure of the pump 3 becomes extremely high, and the discharge pressure of the fixed hydraulic pump 3 becomes low during a steady turn.
【0040】前記固定油圧ポンプ3はギヤポンプとして
あり、その吐出圧が高くなると内部洩れ量が増大して効
率が低下するので、固定油圧ポンプ3の吐出流量は同一
回転数であっても吐出圧が高圧の場合には低圧の場合よ
りも減少する。The fixed hydraulic pump 3 is a gear pump. When the discharge pressure of the fixed hydraulic pump 3 increases, the internal leakage increases and the efficiency decreases. In the case of high pressure, it decreases more than in the case of low pressure.
【0041】固定油圧ポンプ3の吐出流量が減少すると
絞り18前後の差圧(P2 −P3 )が小さくなるので、
旋回油圧モータ76を起動する時には絞り18前後の差
圧(P2 −P3 )が小さく、定常回転時には絞り18前
後の差圧(P2 −P3 )が大きくなる。When the discharge flow rate of the fixed hydraulic pump 3 decreases, the differential pressure (P 2 -P 3 ) before and after the throttle 18 decreases,
The diaphragm 18 of the differential pressure across when starting the hydraulic swing motor 76 (P 2 -P 3) is small, aperture to steady rotation 18 of the differential pressure across (P 2 -P 3) is increased.
【0042】このために、パイロット回路70に第1・
第2絞り71,73がなく絞り18の下流側圧力P3 を
制御弁26の第2補助受圧部33に直接作用した場合に
は制御弁26の第1補助受圧部31に作用する圧力と第
2補助受圧部33に作用する圧力の差圧が、旋回油圧モ
ータ76を起動する時と定常回転時とで変化し、可変油
圧ポンプ2の吐出流量が異なる。To this end, the pilot circuit 70 has a first
When the downstream side pressure P 3 of the throttle 18 is directly applied to the second auxiliary pressure receiving portion 33 of the control valve 26 without the second throttles 71 and 73, the pressure acting on the first auxiliary pressure receiving portion 31 of the control valve 26 and 2 The differential pressure of the pressure acting on the auxiliary pressure receiving portion 33 changes between the time when the swing hydraulic motor 76 is started and the time when it is in steady rotation, and the discharge flow rate of the variable hydraulic pump 2 is different.
【0043】しかしながら、図4に示すようにパイロッ
ト回路70に第1・第2絞り71,73を設けること
で、制御弁26の第2補助受圧部33に作用する圧力P
4 が絞り18の下流側圧力P3 よりも一定の比率で低圧
となるので、前述のように固定油圧ポンプ3の吐出流量
が吐出圧力による効率低下によって減少しても制御弁2
6の第1補助受圧部31と第2補助受圧部33に作用す
る圧力の差圧がほぼ一定となり、旋回油圧モータ76の
起動時と定常回転時とで可変油圧ポンプ2の吐出流量が
変化しないようになる。However, by providing the pilot circuit 70 with the first and second throttles 71 and 73 as shown in FIG. 4, the pressure P acting on the second auxiliary pressure receiving portion 33 of the control valve 26 is increased.
Since the pressure of 4 becomes lower than the pressure P 3 on the downstream side of the throttle 18 at a constant ratio, as described above, even if the discharge flow rate of the fixed hydraulic pump 3 decreases due to a decrease in efficiency due to discharge pressure, the control valve 2
The differential pressure of the pressures acting on the first auxiliary pressure receiving portion 31 and the second auxiliary pressure receiving portion 33 becomes substantially constant, and the discharge flow rate of the variable hydraulic pump 2 does not change between when the swing hydraulic motor 76 is started and when it is steadily rotating. Like
【0044】例えば、旋回油圧モータ26が定常回転時
には固定油圧ポンプ3の吐出圧が50kg/cm2 で吐
出流量が20l/minで、絞り18の下流側圧力P3
が40kg/cm2 、第2補助受圧部33の圧力P4 が
39.5kg/cm2 とすると、制御弁26の第1補助
受圧部31に作用する圧力P2 と第2補助受圧部33に
作用する圧力P4 の差圧(P2 −P4 )は10kg/c
m2 となる。For example, when the swing hydraulic motor 26 is in steady rotation, the discharge pressure of the fixed hydraulic pump 3 is 50 kg / cm 2 , the discharge flow rate is 20 l / min, and the pressure P 3 on the downstream side of the throttle 18 is small.
There 40 kg / cm 2, the pressure P 4 of the second auxiliary pressure receiving portion 33 and 39.5kg / cm 2, the pressure P 2 and the second auxiliary pressure receiving section 33 that acts on the first auxiliary pressure receiving portion 31 of the control valve 26 differential pressure of the pressure P 4 acting (P 2 -P 4) is 10 kg / c
It becomes m 2 .
【0045】前述の状態において旋回油圧モータ起動時
には固定油圧ポンプ3の吐出圧力が200kg/cm2
で吐出流量が18l/minとなると、絞り18の下流
側圧力P3 が192kg/cm2 となり、第2補助受圧
部33に作用する圧力P4 はほぼ189.5kg/cm
2 となるので、前記の差圧(P2 −P4 )はほぼ10k
g/cm2 となる。In the above-mentioned state, when the swing hydraulic motor is started, the discharge pressure of the fixed hydraulic pump 3 is 200 kg / cm 2
When the discharge flow rate becomes 18 l / min, the downstream pressure P 3 of the throttle 18 becomes 192 kg / cm 2 , and the pressure P 4 acting on the second auxiliary pressure receiving portion 33 is approximately 189.5 kg / cm.
Since the 2, the differential pressure (P 2 -P 4) is approximately 10k
It becomes g / cm 2 .
【0046】図5は第3実施例を示し、前記制御弁26
のドレーンポート29を入力トルク制御用の切換弁80
でタンク15と吐出路4の一方に接続するようにしてあ
る。FIG. 5 shows a third embodiment, in which the control valve 26
The drain port 29 of the switching valve 80 for input torque control
Is connected to one of the tank 15 and the discharge path 4.
【0047】前記切換弁80はスプリング81でドレー
ン位置Cに押され、第1受圧部82に作用するポンプ吐
出圧と第2受圧部83に作用する外部圧力で供給位置D
に押され、スプリング81はリンク84でピストン22
に連係されている。The switching valve 80 is pushed to the drain position C by the spring 81, and the supply position D is adjusted by the pump discharge pressure acting on the first pressure receiving portion 82 and the external pressure acting on the second pressure receiving portion 83.
The spring 81 is pushed by the link 84 to the piston 22.
Is associated with.
【0048】このようであるから、ポンプ吐出圧がスプ
リング81の取付荷重に見合う圧力より高くなると切換
弁80が供給位置Dとなってポンプ吐出圧が制御弁26
を経て大径受圧室23に流入してピストン22が右方に
移動して斜板20が容量小方向に傾転し、ピストン22
の移動によってリンク84を介してスプリング81の取
付荷重が大となって切換弁80はドレーン位置Cに押さ
れる。Therefore, when the pump discharge pressure becomes higher than the pressure commensurate with the mounting load of the spring 81, the switching valve 80 becomes the supply position D and the pump discharge pressure becomes the control valve 26.
Through the large-diameter pressure receiving chamber 23, the piston 22 moves to the right, and the swash plate 20 tilts in the small capacity direction.
The load of the spring 81 increases due to the movement of the switch 81, and the switching valve 80 is pushed to the drain position C.
【0049】このような動作が繰り返して行なわれて可
変油圧ポンプ2の容量は入力トルク(ポンプ吐出圧×容
量)が一定となるように制御される。By repeating such operations, the displacement of the variable hydraulic pump 2 is controlled so that the input torque (pump discharge pressure × capacity) becomes constant.
【0050】[0050]
【発明の効果】第1の発明によれば、エンジン1の回転
数が低速の時には固定容量型油圧ポンプ3の吐出流量が
少なく絞り18前後の差圧が小さくなって制御弁26の
差圧セット力が小さくなり、エンジン1の回転数が高速
の時には固定容量型油圧ポンプ3その吐出流量が多く絞
り18前後の差圧が大きくなって制御弁26の差圧セッ
ト力が大きくなる。したがって、エンジン1が低速回転
数の時に可変容量型油圧ポンプ2の吐出流量が著しく少
なくなって微少操作性が向上する。According to the first aspect of the present invention, when the rotational speed of the engine 1 is low, the discharge flow rate of the fixed displacement hydraulic pump 3 is small and the differential pressure before and after the throttle 18 is small, so that the differential pressure set by the control valve 26 is set. When the force becomes small and the rotation speed of the engine 1 is high, the discharge flow rate of the fixed displacement hydraulic pump 3 is large, the differential pressure before and after the throttle 18 is large, and the differential pressure setting force of the control valve 26 is large. Therefore, the discharge flow rate of the variable displacement hydraulic pump 2 is remarkably reduced when the engine 1 is operating at a low speed, and the operability is improved.
【0051】また、固定容量型油圧ポンプ3の吐出路1
6に設けた絞り18の前後差圧によって制御弁26の差
圧セット力を変更するので、その固定容量型油圧ポンプ
3の吐出圧油がタンクに流出することなく有効利用でき
るし、その吐出圧油を他の油圧機器に供給しても絞り1
8前後差圧が変化せずに可変容量型油圧ポンプの容量制
御特性を一定にでき、しかもエンジン1が極めて低速の
時でも絞り18前後差圧が発生して可変容量型油圧ポン
プ2の容量をエンジン回転数を加味して制御できる。The discharge passage 1 of the fixed displacement hydraulic pump 3
Since the differential pressure setting force of the control valve 26 is changed by the differential pressure across the throttle 18 provided at 6, the discharge pressure oil of the fixed displacement hydraulic pump 3 can be effectively used without flowing out to the tank, and the discharge pressure Throttling 1 even if oil is supplied to other hydraulic equipment
8 The displacement control characteristic of the variable displacement hydraulic pump can be made constant without changing the front-rear differential pressure, and even when the engine 1 is at an extremely low speed, the throttle 18 front-rear differential pressure is generated to change the displacement of the variable displacement hydraulic pump 2. It can be controlled by considering the engine speed.
【0052】第2の発明によれば、制御弁26の第2補
助受圧部33に作用する圧力P4 は、固定容量型油圧ポ
ンプ3の吐出路16に設けた絞り18の下流側圧力P3
を一定比率で減圧した値となり、エンジン1の回転数が
一定で固定容量型油圧ポンプ3の吐出圧による効率変化
に伴ない吐出流量が変化した場合でも制御弁26の第1
補助受圧部31と第2補助受圧部33との圧力差がほぼ
同一となる。したがって、固定容量型油圧ポンプ3の回
転速度が同一で、その吐出圧が高圧、低圧に変化した場
合に制御弁26の差圧セット力がほぼ同一となり、可変
容量型油圧ポンプ2の吐出流量がほぼ同一となる。According to the second invention, the pressure P 4 acting on the second auxiliary pressure receiving portion 33 of the control valve 26 is the pressure P 3 on the downstream side of the throttle 18 provided in the discharge passage 16 of the fixed displacement hydraulic pump 3.
Is a value reduced by a constant ratio, and even when the rotation speed of the engine 1 is constant and the discharge flow rate changes due to a change in efficiency due to the discharge pressure of the fixed displacement hydraulic pump 3,
The pressure difference between the auxiliary pressure receiving portion 31 and the second auxiliary pressure receiving portion 33 becomes substantially the same. Therefore, when the rotation speed of the fixed displacement hydraulic pump 3 is the same and the discharge pressure thereof changes to high pressure and low pressure, the differential pressure setting force of the control valve 26 becomes substantially the same, and the discharge flow rate of the variable displacement hydraulic pump 2 becomes It will be almost the same.
【図1】本発明の第1の実施例を示す線図的構成説明図
である。FIG. 1 is a schematic configuration explanatory view showing a first embodiment of the present invention.
【図2】エンジン回転数と吐出流量の関係を示す図表で
ある。FIG. 2 is a chart showing the relationship between engine speed and discharge flow rate.
【図3】制御弁の具体構造を示す断面図である。FIG. 3 is a sectional view showing a specific structure of a control valve.
【図4】本発明の第2の実施例を示す線図的構成説明図
である。FIG. 4 is a schematic configuration explanatory view showing a second embodiment of the present invention.
【図5】本発明の第3の実施例を示す線図的構成説明図
である。FIG. 5 is a schematic configuration explanatory view showing a third embodiment of the present invention.
1…エンジン 2…可変容量型油圧ポンプ 3…固定容量型油圧ポンプ 4…吐出路 5…操作弁 16…吐出路 18…絞り 21…シリンダ 23…大径受圧室 24…小径受圧室 26…制御弁 27…第1ポート 28…第2ポート 29…ドレーンポート 30…第1受圧部 31…第1補助受圧部 32…第2受圧部 33…第2補助受圧部 40…弁本体 41…スリーブ孔 42…スリーブ 48…スプール 49…スプリング 55…第1受圧室 56…第2受圧室 58…第3受圧室 61…第4受圧室 66…流出ポート 67…制御ポート 68…ポンプ圧供給ポート 70…パイロット回路 71…第1絞り 72…ドレーン回路 73…第2絞り 80…切換弁 81…スプリング 84…リンク。 DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Variable displacement hydraulic pump 3 ... Fixed displacement hydraulic pump 4 ... Discharge passage 5 ... Operation valve 16 ... Discharge passage 18 ... Restrictor 21 ... Cylinder 23 ... Large diameter pressure receiving chamber 24 ... Small diameter pressure receiving chamber 26 ... Control valve 27 ... 1st port 28 ... 2nd port 29 ... Drain port 30 ... 1st pressure receiving part 31 ... 1st auxiliary pressure receiving part 32 ... 2nd pressure receiving part 33 ... 2nd auxiliary pressure receiving part 40 ... Valve main body 41 ... Sleeve hole 42 ... Sleeve 48 ... Spool 49 ... Spring 55 ... First pressure receiving chamber 56 ... Second pressure receiving chamber 58 ... Third pressure receiving chamber 61 ... Fourth pressure receiving chamber 66 ... Outflow port 67 ... Control port 68 ... Pump pressure supply port 70 ... Pilot circuit 71 ... first throttle 72 ... drain circuit 73 ... second throttle 80 ... switching valve 81 ... spring 84 ... link.
Claims (4)
るシリンダ21と、このシリンダ21にポンプ吐出圧を
供給制御する制御弁26と、前記可変容量型油圧ポンプ
2と同一のエンジン1で駆動される固定容量型油圧ポン
プ3と、その吐出路16に設けた絞り18を備え、 前記制御弁26を、ポンプ吐出圧と負荷圧の差圧と差圧
セット力との大小関係によって切換作動されて前記差圧
を差圧セット力に見合う一定の値とし、かつ前記絞18
前後の差圧が大きい時には差圧セット力を大きく、小さ
い時には差圧セット力を小さくするものとした可変容量
型油圧ポンプの容量制御装置。1. A cylinder 21 that controls the displacement of a variable displacement hydraulic pump 2, a control valve 26 that controls the supply of pump discharge pressure to the cylinder 21, and an engine 1 that is the same as the variable displacement hydraulic pump 2. A fixed displacement hydraulic pump 3 and a throttle 18 provided in the discharge passage 16 of the fixed displacement hydraulic pump 3, and the control valve 26 is switched and operated depending on the magnitude relation between the pump discharge pressure, the load pressure differential pressure, and the differential pressure setting force. The differential pressure to a constant value corresponding to the differential pressure setting force, and the throttle 18
A displacement control device for a variable displacement hydraulic pump, which sets a large differential pressure setting force when the front-rear differential pressure is large, and reduces the differential pressure setting force when it is small.
油が供給されると容量小方向に移動し、その大径受圧室
23がドレーンに連通すると容量大方向に移動するもの
とし、 前記制御弁26を、第1受圧部30と第1補助受圧部3
1の圧力で大径受圧室23をドレーンに連通するドレー
ン位置Aとなり、第2受圧部32と第2補助受圧部33
の圧油で大径受圧室23にポンプ吐出圧を供給する供給
位置Bとなるものとし、 前記第1受圧部30に負荷圧を供給し、第2受圧部32
にポンプ吐出圧を供給し、第1補助受圧部31に絞り1
8上流側圧力を供給し、第2補助受圧部33に絞り18
下流側圧力を供給した請求項1記載の可変容量型油圧ポ
ンプの容量制御装置。2. The cylinder 21 moves in a small capacity direction when pressure oil is supplied to the large diameter pressure receiving chamber 23, and moves in the large capacity direction when the large diameter pressure receiving chamber 23 communicates with a drain, The control valve 26 is connected to the first pressure receiving portion 30 and the first auxiliary pressure receiving portion 3
With the pressure of 1, it becomes the drain position A where the large diameter pressure receiving chamber 23 communicates with the drain, and the second pressure receiving portion 32 and the second auxiliary pressure receiving portion 33 are provided.
It is assumed that the supply position B for supplying the pump discharge pressure to the large diameter pressure receiving chamber 23 with the above pressure oil is applied, the load pressure is supplied to the first pressure receiving portion 30, and the second pressure receiving portion 32 is supplied.
Pump discharge pressure to the first auxiliary pressure receiving portion 31
8 upstream side pressure is supplied, and the second auxiliary pressure receiving portion 33 is throttled 18
The displacement control device for a variable displacement hydraulic pump according to claim 1, wherein a downstream pressure is supplied.
るシリンダ21と、このシリンダ21にポンプ吐出圧を
供給制御する制御弁26と、前記可変容量型油圧ポンプ
2と同一のエンジン1で駆動される固定容量型油圧ポン
プ3と、その吐出路16に設けた絞り18を備え、 前記シリンダ21を大径受圧室23に圧油が供給される
と容量小方向に移動し、その大径受圧室23がドレーン
に連通すると容量大方向に移動するものとし、 前記制御弁26を、第1受圧部30と第1補助受圧部3
1の圧力で大径受圧室23をドレーンに連通するドレー
ン位置Aとなり、第2受圧部32と第2補助受圧部33
の圧油で大径受圧室23にポンプ吐出圧を供給する供給
位置Bとなるものとし、 前記第1受圧部30に負荷圧を供給し、第2受圧部32
にポンプ吐出圧を供給し、第1補助受圧部31に絞り1
8上流側圧力を供給し、第2補助受圧部33に絞り18
下流側に接続したドレーン路における第1絞りと第2絞
りとの中間の圧力を供給した可変容量型油圧ポンプの容
量制御装置。3. A cylinder 21 that controls the displacement of the variable displacement hydraulic pump 2, a control valve 26 that controls the supply of pump discharge pressure to the cylinder 21, and an engine 1 that is the same as the variable displacement hydraulic pump 2. Is provided with a fixed displacement hydraulic pump 3 and a throttle 18 provided in the discharge passage 16, and when the pressure oil is supplied to the large diameter pressure receiving chamber 23, the cylinder 21 moves in the small capacity direction to receive the large diameter pressure reception. It is assumed that when the chamber 23 communicates with the drain, the chamber 23 moves in the large capacity direction, and the control valve 26 is connected to the first pressure receiving portion 30 and the first auxiliary pressure receiving portion 3.
With the pressure of 1, it becomes the drain position A where the large diameter pressure receiving chamber 23 communicates with the drain, and the second pressure receiving portion 32 and the second auxiliary pressure receiving portion 33 are provided.
It is assumed that the supply position B for supplying the pump discharge pressure to the large diameter pressure receiving chamber 23 with the above pressure oil is applied, the load pressure is supplied to the first pressure receiving portion 30, and the second pressure receiving portion 32 is supplied.
Pump discharge pressure to the first auxiliary pressure receiving portion 31
8 upstream side pressure is supplied, and the second auxiliary pressure receiving portion 33 is throttled 18
A displacement control device for a variable displacement hydraulic pump that supplies an intermediate pressure between a first throttle and a second throttle in a drain path connected to a downstream side.
42を嵌挿し、そのスリーブ42内にスプール48を嵌
挿して受圧径の等しい第1受圧室55と第4受圧室61
及び受圧径の等しい第2受圧室56と第3受圧室58を
形成し、 前記第1受圧室55の圧力と第4受圧室61の圧力の差
圧とスプリング49でスプール48を、ポンプ圧供給ポ
ート68と制御ポート67と流出ポート66を連通・遮
断する位置に移動し、第2受圧室56の圧力と第3受圧
室58の圧力の差圧でスプール48をスプリング49に
抗する方向に押すようにして制御弁26とし、 前記第1受圧室55にポンプ吐出圧を供給し、第4受圧
室61に負荷圧を供給し、第2受圧室56に絞り18下
流側圧を供給し、第3受圧室58を絞り18上流側圧を
供給した請求項1又は2又は3記載の可変容量型油圧ポ
ンプの容量制御装置。4. A first pressure receiving chamber 55 and a fourth pressure receiving chamber 61 having the same pressure receiving diameter by inserting a sleeve 42 into a sleeve hole 41 of a valve body 40 and inserting a spool 48 into the sleeve 42.
The second pressure receiving chamber 56 and the third pressure receiving chamber 58 having the same pressure receiving diameter are formed, and the spool 48 is supplied by the pressure difference between the pressure of the first pressure receiving chamber 55 and the pressure of the fourth pressure receiving chamber 61 and the spring 49 to the spool 48. The port 68, the control port 67, and the outflow port 66 are moved to a position where they communicate / block, and the differential pressure between the pressure in the second pressure receiving chamber 56 and the pressure in the third pressure receiving chamber 58 pushes the spool 48 against the spring 49. In this way, the control valve 26 is provided, the pump discharge pressure is supplied to the first pressure receiving chamber 55, the load pressure is supplied to the fourth pressure receiving chamber 61, and the throttle 18 downstream side pressure is supplied to the second pressure receiving chamber 56. The displacement control device for a variable displacement hydraulic pump according to claim 1, 2 or 3, wherein the pressure receiving chamber 58 is supplied with the upstream pressure of the throttle 18.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP7214736A JPH08338405A (en) | 1995-04-12 | 1995-08-23 | Capacity control device for variable displacement hydraulic pump |
PCT/JP1996/001005 WO1996032593A1 (en) | 1995-04-12 | 1996-04-11 | Displacement controlling device for a variable displacement type hydraulic pump |
EP96909349A EP0821167A4 (en) | 1995-04-12 | 1996-04-11 | Displacement controlling device for a variable displacement type hydraulic pump |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP7-86697 | 1995-04-12 | ||
JP8669795 | 1995-04-12 | ||
JP7214736A JPH08338405A (en) | 1995-04-12 | 1995-08-23 | Capacity control device for variable displacement hydraulic pump |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH08338405A true JPH08338405A (en) | 1996-12-24 |
Family
ID=26427791
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP7214736A Pending JPH08338405A (en) | 1995-04-12 | 1995-08-23 | Capacity control device for variable displacement hydraulic pump |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0821167A4 (en) |
JP (1) | JPH08338405A (en) |
WO (1) | WO1996032593A1 (en) |
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CN100342136C (en) * | 2000-08-02 | 2007-10-10 | 株式会社小松制作所 | Volume control device for oil pump |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3679300B2 (en) * | 1999-06-10 | 2005-08-03 | 日立建機株式会社 | Volume control valve for variable displacement hydraulic rotating machine |
DE10344152A1 (en) * | 2003-09-22 | 2005-04-21 | Klaus Riedel | Combination bolt securing a valve block to a hydraulic piston-driven pump is fabricated as a one-piece component |
US11486277B2 (en) | 2021-02-26 | 2022-11-01 | Deere & Company | Work vehicle engine with split-circuit lubrication system |
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DE2141724A1 (en) * | 1971-08-20 | 1973-03-01 | Bosch Gmbh Robert | CONTROL AND REGULATING DEVICE FOR A HYDROPUMP |
US4017216A (en) * | 1976-03-15 | 1977-04-12 | Caterpillar Tractor Co. | Variable underspeed system linkage |
KR920007650B1 (en) * | 1989-02-20 | 1992-09-14 | 히다찌 겐끼 가부시기가이샤 | Hyydraulic circuit for working machines |
DE4115606A1 (en) * | 1991-05-14 | 1992-11-19 | Putzmeister Maschf | OVERLOAD PROTECTION DEVICE FOR A DRIVE ENGINE DESIGNED AS AN INTERNAL COMBUSTION ENGINE OF A MAIN PUMP OF A HYDRAULIC PRESSURE SUPPLY UNIT |
JPH0599126A (en) | 1991-10-07 | 1993-04-20 | Komatsu Ltd | Capacity control device for variable capacity type hydraulic pump |
JPH05172107A (en) | 1991-12-24 | 1993-07-09 | Komatsu Ltd | Capacity control device for variable hydraulic pump |
JPH0586003U (en) | 1992-04-23 | 1993-11-19 | 内田油圧機器工業株式会社 | Differential pressure generator for load sensing |
JP3179596B2 (en) * | 1992-11-17 | 2001-06-25 | 日立建機株式会社 | Flow control device |
-
1995
- 1995-08-23 JP JP7214736A patent/JPH08338405A/en active Pending
-
1996
- 1996-04-11 WO PCT/JP1996/001005 patent/WO1996032593A1/en not_active Application Discontinuation
- 1996-04-11 EP EP96909349A patent/EP0821167A4/en not_active Ceased
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN100342136C (en) * | 2000-08-02 | 2007-10-10 | 株式会社小松制作所 | Volume control device for oil pump |
Also Published As
Publication number | Publication date |
---|---|
EP0821167A4 (en) | 1998-09-02 |
EP0821167A1 (en) | 1998-01-28 |
WO1996032593A1 (en) | 1996-10-17 |
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