JP3006777B2 - Load sensing hydraulic circuit - Google Patents

Load sensing hydraulic circuit

Info

Publication number
JP3006777B2
JP3006777B2 JP3075708A JP7570891A JP3006777B2 JP 3006777 B2 JP3006777 B2 JP 3006777B2 JP 3075708 A JP3075708 A JP 3075708A JP 7570891 A JP7570891 A JP 7570891A JP 3006777 B2 JP3006777 B2 JP 3006777B2
Authority
JP
Japan
Prior art keywords
pressure
valve
pls3
pls
hydraulic
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.)
Expired - Fee Related
Application number
JP3075708A
Other languages
Japanese (ja)
Other versions
JPH04285303A (en
Inventor
寛 今井
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Komatsu Ltd
Original Assignee
Komatsu Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Komatsu Ltd filed Critical Komatsu Ltd
Priority to JP3075708A priority Critical patent/JP3006777B2/en
Priority to PCT/JP1992/000268 priority patent/WO1992016754A1/en
Publication of JPH04285303A publication Critical patent/JPH04285303A/en
Application granted granted Critical
Publication of JP3006777B2 publication Critical patent/JP3006777B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/165—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for adjusting the pump output or bypass in response to demand
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2225—Control of flow rate; Load sensing arrangements using pressure-compensating 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/163—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/0416—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor with means or adapted for load sensing
    • F15B13/0417—Load sensing elements; Internal fluid connections therefor; Anti-saturation or pressure-compensation 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
    • F15B2211/20—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
    • F15B2211/25—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
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check 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
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • 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
    • F15B2211/30—Directional control
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/31523—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source and an output member
    • F15B2211/31529—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source and an output member having a single pressure source and a single output member
    • 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
    • F15B2211/30—Directional control
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31576—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and a single output member
    • 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
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional 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
    • F15B2211/60—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
    • F15B2211/6054—Load sensing circuits having valve means between output member and the load sensing circuit using shuttle 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6306—Electronic controllers using input signals representing a pressure
    • F15B2211/6316—Electronic controllers using input signals representing a pressure the pressure being a pilot 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
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means
    • 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
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6653—Pressure control
    • 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
    • F15B2211/7142—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being arranged in multiple groups

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Operation Control Of Excavators (AREA)
  • Fluid-Pressure Circuits (AREA)

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本発明は、ロードセンシング油圧
回路に関する。The present invention relates, on the load Sensing grayed oil pressure circuit.

【０００２】[0002]

【従来の技術】ロードセンシングシステムを備えた油圧
駆動装置を搭載した車両、たとえば油圧式掘削機におい
ては、図４に示す油圧回路を用いている。同図は、走行
用油圧モータ（以下走行モータという）と、ブーム、ア
ーム、バケット等の作業機を駆動する油圧アクチュエー
タのうちブームシリンダに関する油圧回路の概略構成を
示したもので、エンジン等の動力源によって駆動される
１個の可変容量形油圧ポンプ（以下ポンプという）１
と、このポンプ１が吐出する圧油によって駆動される左
側駆動輪の走行モータ２L、 右側駆動輪の走行モータ２
R、 ブームシリンダ２B と、ポンプ１から前記走行モー
タ２L，２Rおよびブームシリンダ２Bに送られる圧油の
方向を切り換えるクローズドセンタの方向切換弁 ３L，
３R，３Bと、ポンプ１が吐出する圧油の流量を制御する
レギュレータ４およびＬＳ弁５とを備えている。2. Description of the Related Art In a vehicle equipped with a hydraulic drive device equipped with a load sensing system, for example, a hydraulic excavator, a hydraulic circuit shown in FIG. 4 is used. FIG. 1 shows a schematic configuration of a hydraulic circuit for a boom cylinder among hydraulic actuators for driving a working machine such as a boom, an arm, and a bucket. One variable displacement hydraulic pump (hereinafter referred to as pump) 1 driven by a power source
And a traveling motor 2L for the left driving wheel and a traveling motor 2L for the right driving wheel driven by the pressure oil discharged from the pump 1.
R, a boom cylinder 2B, and a closed center direction switching valve 3L, which switches the direction of pressure oil sent from the pump 1 to the traveling motors 2L, 2R and the boom cylinder 2B.
3R, 3B, a regulator 4 for controlling the flow rate of the pressure oil discharged from the pump 1 and an LS valve 5 are provided.

【０００３】前記ＬＳ弁５の一端には、回路６から分岐
するパイロット回路１６によってポンプ１の吐出圧ＰP
が導かれ、他端には走行モータ２L，２Rをはじめとする
各アクチュエータの負荷圧のうち最高の圧力ＰLSが、シ
ャトル弁１０，１１およびパイロット回路１２などを介
して導かれている。また、方向切換弁３L，３R，３B の
出口ポートにそれぞれ設けられた圧力補償弁８L，８R，
８B にも前記圧力ＰLSがパイロット回路１５L，１５R，
１５B を介して導かれている。At one end of the LS valve 5, a discharge pressure PP of the pump 1 is controlled by a pilot circuit 16 branched from the circuit 6.
The highest pressure PLS among the load pressures of the actuators such as the traveling motors 2L and 2R is guided to the other end via the shuttle valves 10, 11 and the pilot circuit 12. Further, pressure compensating valves 8L, 8R, provided at outlet ports of the directional control valves 3L, 3R, 3B, respectively.
8B, the pressure PLS is also applied to the pilot circuits 15L, 15R,
15B.

【０００４】アクチュエータに供給される圧油流量ＱA
は、ポンプ吐出圧を ＰP、流量係数をｃ、方向切換弁の
開口面積をＡ、アクチュエータ負荷圧をＰLSとすると、
下記の式で表すことができる。 ＱA ＝ｃ×Ａ×（ＰP−ＰLS）1/2 差圧ＰP−ＰLS は一定になるように制御されているの
で、アクチュエータ流量ＱA は方向切換弁の開口面積Ａ
すなわち操作レバーの操作ストロークに応じて制御され
ることになる。The flow rate of the pressure oil supplied to the actuator QA
Is Pp, the pump discharge pressure is PP, the flow coefficient is c, the opening area of the directional control valve is A, and the actuator load pressure is PLS.
It can be represented by the following equation. QA = c.times.A.times. (PP-PLS) Since the 1/2 differential pressure PP-PLS is controlled to be constant, the actuator flow rate QA is changed to the opening area A of the directional control valve.
That is, the control is performed according to the operation stroke of the operation lever.

【０００５】[0005]

【発明が解決しようとする課題】油圧式掘削機が作業現
場内を走行しながらブーム、アーム、バケット等の作業
機を駆動することがある。このような複合操作をする
と、下記理由により走行の減速率が大きい。 今、ポン
プ１の吐出圧をＰP、吐出量を ＱPとし、左走行モータ
２L、右走行モータ２R への流量をそれぞれＱ1，Ｑ2、
作業機たとえばブームを駆動するブームシリンダ２B へ
の流量をＱ3、前記各アクチュエータを制御する方向切
換弁３L，３R，３B の開口面積をそれぞれＡ1，Ａ2，Ａ
3とし、方向切換弁３L，３R，３Bの出口圧をそれぞれＰ
1，Ｐ2，Ｐ3、各アクチュエータの負荷圧をそれぞれＰL
S1，ＰLS2，ＰLS3、流量係数をｃとすると、ブームシリ
ンダ負荷圧ＰLS3 が走行モータの負荷圧ＰLS1，ＰLS2よ
り大きいので、各圧力補償弁８L，８R，８Bには前記ＰL
S3 が作用する。従って、圧力補償弁８L，８Rは走行の
みを行っているときよりも大きく絞られ、走行モータ２
L，２Rに供給される流量が減るため、減速されることに
なる。このときの各アクチュエータへの流量は、それぞ
れ下記の式で表すことができる。 Ｑ1 ＝ｃ×Ａ1×（ＰP−Ｐ1）1/2≒ｃ×Ａ1×（ＰP−ＰLS3）1/2 Ｑ2 ＝ｃ×Ａ2×（ＰP−Ｐ2）1/2≒ｃ×Ａ2×（ＰP−ＰLS3）1/2 Ｑ3 ＝ｃ×Ａ3×（ＰP−Ｐ3）1/2≒ｃ×Ａ3×（ＰP−ＰLS3）1/2 各アクチュエータへの流量配分は、ＱP ＝Ｑ1＋Ｑ2＋Ｑ
3 であるから、 Ｑ1＝Ａ1／（Ａ1＋Ａ2＋Ａ3）×ＱP Ｑ2＝Ａ2／（Ａ1＋Ａ2＋Ａ3）×ＱP Ｑ3＝Ａ3／（Ａ1＋Ａ2＋Ａ3）×ＱP となる。In some cases, a hydraulic excavator drives a working machine such as a boom, an arm, and a bucket while traveling in a work site. When such a combined operation is performed, the traveling deceleration rate is large for the following reasons. Now, assuming that the discharge pressure of the pump 1 is PP and the discharge amount is QP, the flow rates to the left traveling motor 2L and the right traveling motor 2R are Q1, Q2,
The flow rate to a work machine, for example, a boom cylinder 2B for driving a boom, is Q3, and the opening areas of the directional control valves 3L, 3R, 3B for controlling the actuators are A1, A2, A, respectively.
3, and the outlet pressures of the directional control valves 3L, 3R, 3B are respectively P
1, P2, P3, and the load pressure of each actuator
Assuming that S1, PLS2, PLS3 and the flow coefficient are c, the boom cylinder load pressure PLS3 is larger than the load pressure PLS1, PLS2 of the traveling motor, so that each of the pressure compensating valves 8L, 8R, 8B has the above PL.
S3 works. Therefore, the pressure compensating valves 8L and 8R are throttled more than when only traveling, and the traveling motor 2
Since the flow rate supplied to L and 2R is reduced, the speed is reduced. The flow rate to each actuator at this time can be represented by the following equation. Q1 = c × A1 × (PP-P1) 1/2 ≒ c × A1 × (PP-PLS3) 1/2 Q2 = c × A2 × (PP-P2) 1/2 ≒ c × A2 × (PP-PLS3 ) 1/2 Q3 = c x A3 x (PP-P3) 1/2 ≒ c x A3 x (PP-PLS3) 1/2 The flow distribution to each actuator is as follows: QP = Q1 + Q2 + Q
Therefore, Q1 = A1 / (A1 + A2 + A3) .times.QP Q2 = A2 / (A1 + A2 + A3) .times.QP Q3 = A3 / (A1 + A2 + A3) .times.QP.

【０００６】上記不具合の対策として走行用油圧回路に
設置された圧力補償弁のばね張力を小さくして、圧力補
償特性をゆるくすると、直進走行から緩旋回したとき、
旋回外側の駆動輪の走行速度が低下して、オペレータの
意図した通りに車両を操作することができない。As a countermeasure against the above-mentioned problem, if the spring tension of the pressure compensating valve installed in the traveling hydraulic circuit is reduced to loosen the pressure compensating characteristics, when the vehicle turns slowly from straight running,
The traveling speed of the drive wheels on the outside of the turn is reduced, and the vehicle cannot be operated as intended by the operator.

【０００７】本発明は上記従来の問題点に着目し、走行
と作業機駆動とを同時に行った場合に、走行減速率を可
能な限り小さくし、オペレータの意志通りに車両を操作
することができるような、ロードセンシング油圧回路を
提供することを目的とする。The present invention pays attention to the above-mentioned conventional problems, and makes it possible to reduce the traveling deceleration rate as much as possible and to operate the vehicle as the operator intends when traveling and driving of the work machine are performed simultaneously. such, and an object thereof is to provide a load Sensing grayed oil pressure circuit.

【０００８】[0008]

【課題を解決するための手段】上記目的を達成するため
に本発明に係るロードセンシング油圧回路は、例えば図
１、図２及びこれらに記載の要素符号を参照して説明す
れば、可変容量形油圧ポンプ(1) の吐出側に複数の方向
切換弁(3L,3R,3B)を並列接続し、かつ各方向切換弁(3L,
3R,3B)の下流側にそれぞれの油圧アクチュエータ(2L,2
R,2B)を接続すると共に、各方向切換弁(3L,3R,3B)とそ
れぞれの油圧アクチュエータ(2L,2R,2B)との間に各油圧
アクチュエータ(2L,2R,2B)の内の最大負荷圧(PLS3)を受
けてそれぞれの方向切換弁(3L,3R,3B)の出口圧(P1,P2,P
3)を最大負荷圧(PLS3)に一致させる圧力補償弁(8L,8R,8
B)をそれぞれ設け、かつ可変容量形油圧ポンプ(1) が自
己吐出圧(Pp)と最大負荷圧(PLS3)とを受けて自己吐出圧
(Pp)が最大負荷圧(PLS3)よりも所定圧だけ高くなるよう
に自己吐出量を可変制御するロードセンシング油圧回路
において、 各圧力補償弁(8L,8R,8B)が受ける最大負荷圧
(PLS3)を降圧(PLS')自在とする圧力変更手段(13,14a,14
b,23等) を設けると共に、 前記各圧力補償弁(8L,8R,8B)
は、 それぞれの方向切換弁(3L,3R,3B)の出口圧(P1,P2,P
3)を開方向に受ける第１受圧面とそれぞれの油圧アクチ
ュータ(2L,2R,2B)の負荷圧(PLS1,PLS2,PLS3)を閉方向に
受ける第２受圧面とを備える逆止め弁(8a)と、それぞれ
の油圧アクチュータ(2L,2R,2B)の負荷圧(PLS1,PLS2,PLS
3)を逆止め弁(8a)から離間させる方向に受ける第３受圧
面と最大負荷圧(PLS3)又は降圧(PLS')を逆止め弁(8a)の
閉方向に受ける第４受圧面と逆止め弁(8a)を閉方向に軽
く付勢する弱いバネ(8d)とを備える圧力補償ピストン(8
c)とを備え、かつ第１〜第４受圧面の各面積を同じくし
てあることを特徴としている。Means for Solving the Problems] Load Sensing grayed oil pressure circuit according to the present invention in order to achieve the above object, for example, FIG.
1 and FIG. 2 and the element codes described therein.
The pump on the discharge side of the variable displacement hydraulic pump (1)
Switching valves (3L, 3R, 3B) are connected in parallel, and each directional switching valve (3L,
3R, 3B), each hydraulic actuator (2L, 2B)
R, 2B), and each directional control valve (3L, 3R, 3B)
Hydraulic pressure between each hydraulic actuator (2L, 2R, 2B)
Receives the maximum load pressure (PLS3) of the actuator (2L, 2R, 2B).
Outlet pressure (P1, P2, P2) of each directional control valve (3L, 3R, 3B).
Pressure compensating valve (8L, 8R, 8) that matches 3) to the maximum load pressure (PLS3)
B), and the variable displacement hydraulic pump (1)
Self discharge pressure in response to self discharge pressure (Pp) and maximum load pressure (PLS3)
(Pp) is higher than the maximum load pressure (PLS3) by a predetermined pressure.
Sensing hydraulic circuit that variably controls self-discharge amount
The maximum load pressure received by each pressure compensating valve (8L, 8R, 8B)
Pressure changing means (13, 14a, 14) that allows (PLS3) to step down (PLS ') freely
b, 23, etc.) and the pressure compensating valves (8L, 8R, 8B)
Are the outlet pressures (P1, P2, P2) of the respective directional control valves (3L, 3R, 3B).
3) The first pressure receiving surface and each hydraulic act
(2L, 2R, 2B) load pressure (PLS1, PLS2, PLS3) in the closing direction.
Check valve and a second pressure receiving surface for receiving the (8a), respectively
Load pressure (PLS1, PLS2, PLS) of hydraulic actuators (2L, 2R, 2B)
3) Pressure receiving in the direction to separate 3) from the check valve (8a)
Check the maximum load pressure (PLS3) or the pressure drop (PLS ') with the check valve (8a).
Close the fourth pressure receiving surface and check valve (8a) received in the closing direction
Pressure compensating piston (8
c), and the first to fourth pressure receiving surfaces have the same area.
It is characterized by having .

【０００９】[0009]

【作用及び効果】上記構成によれば、次のような作用効
果を奏する。尚、上記同様、図１、図２及びこれらに記
載の要素符号を参照して説明する。 先ず、上記構成の前
段構成（「〜おいて」）は、例えば図４で示したよう
に、各方向制御弁(3L,3R,3B)の下流側に圧力補償弁(8L,
8R,8B)をそれぞれ設けた形式の従来のロードセンシング
油圧回路を示す。即ち各油圧アクチュエータ(2L,2R,2B)
の負荷圧(PLS1,PLS2,PLS3)が如何であれ、各方向切換弁
(3L,3R,3B)はそれぞれの開口面積に比例した流量をそれ
ぞれの油圧アクチュエータ(2L,2R,2B)に供給する。勿
論、かかる比例供給は、複合操作時における複数油圧ア
クチュエータ(2L,2R,2B)の総要求流量が油圧ポンプ(1)
の最大吐出流量未満であるとき、またリリーフ圧以下で
あるときに成立する。 そこで本願発明は、かかる上記前
段構成のロードセンシング油圧回路において、圧力変更
手段(13,14a,14b,23等) を加設すると共に、従来の圧力
補償弁(8L,8R,8B)を全く異なる圧力補償弁(8L,8R,8B)に
置換し、以上によって発明の特徴としている。そしてこ
の発明の特徴部が後段構成である。詳しくは次の通り。 （１）即ち圧力変更手段(13,14a,14b,23等) によって、
各圧力補償弁(8L,8R,8B)が受ける最大負荷圧(PLS3)を降
圧(PLS')させると、その降圧(PLS')がそれまでの最大負
荷圧(PLS3)に代わって各圧力補償弁(8L,8R,8B)に作用す
る 。尚、油圧ポンプ(1) は最大負荷圧(PLS3)を受けたま
まだから、ポンプ吐出圧(Pp)に変化はない。即ち各方向
切換弁(3L,3R,3B)の入口圧は「Pp」であって変化はな
い。（２）ところが圧力補償弁(8L,8R,8B)は、第１〜第４受
圧面（各面積は同じ）の各受圧方向とそれぞれへの油圧
との関係に基づき次の作用が生ずる。尚、バネ(8d)の付
勢力は、第１〜第４受圧面で生ずる油圧力から見れば無
視できる程度の、かつ逆止め弁(8a)を閉止させるだけの
弱い付勢力である。従ってバネ(8d)及びその付勢力は無
視してよく、また次の説明でも無視している。 （Ａ）最大負荷圧(PLS3)でない側の油圧アクチュエータ
(2L)の負荷圧(PLS1)に対する圧力補償弁(8L)は次の挙動
を示す 。即ち「PLS1＜PLS'」では、方向切換弁(3L)の出
口圧(P1)が降圧(PLS')になるまで補償ピストン(8c)が逆
止め弁(8a)を閉じて流路を絞る。出口圧(P1)が降圧(PL
S')まで昇圧すると、逆止め弁(8a)は開口する。つまり
圧力補償弁(8L)は負荷圧(PLS1)の油を油圧アクチュータ
(2L)に供給する。尚、降圧(PLS')を仮に「PLS'＜PLS1」
にしてしまうと、負荷圧(PLS1)が補償ピストン(8c)を逆
止め弁(8a)から離間させ、これにより「P1＝PLS1」とな
って（即ち圧力補償機能がなくなって）逆止め弁(8a)が
開口し、圧力補償弁(8L)は負荷圧(PLS1)の油を油圧アク
チュータ(2L)に供給する。 （Ｂ）また他の、最大負荷圧(PLS3)でない側の油圧アク
チュエータ(2R)の負荷圧(PLS2)に対する圧力補償弁(8R)
の挙動も上記圧力補償弁(8L)に準ずる。 即ち「PLS2＜PL
S'」では、方向切換弁(3R)の出口圧(P2)が降圧(PLS')に
なるまで補償ピストン(8c)が逆止め弁(8a)を閉じて流路
を絞る。出口圧(P2)が降圧(PLS')まで昇圧すると、逆止
め弁(8a)は開口する。つまり圧力補償弁(8R)は負荷圧(P
LS2)の油を油圧アクチュータ(2R)に供給する。尚、降圧
(PLS')を仮に「PLS'＜PLS2」にしてしまうと、負荷圧(P
LS2)が補償ピストン(8c)を逆止め弁(8a)から離間させ、
これにより「P2＝PLS2」となって（即ち圧力補償機能が
なくなって）逆止め弁(8a)が開口し、圧力補償弁(8B)は
負荷圧(PLS2)の油を油圧アクチュータ(2R)に供給する。 （Ｃ）ところが最大負荷圧(PLS3)側の油圧アクチュエー
タ(2B)の負荷圧(PLS3)に対する圧力補償弁(8B)は次の挙
動を示す。 即ち自己負荷圧(PLS3)が補償ピストン(8c)を
逆止め弁(8a)から離間させ、これにより「P3＝PLS3」と
なって（即ち圧力補償機能がなくなって）逆止め弁(8a)
が開口し、圧力補償弁(8B)は負荷圧(PLS3)の油を油圧ア
クチュータ(2B)に供給する。 （Ｄ）即ち、圧力変更手段(13,14a,14b,23等) によって
各圧力補償弁(8L,8R,8B)が受ける最大負荷圧(PLS3)を降
圧(PLS')させると、その降圧(PLS')がそれまでの最大負
荷圧(PLS3)に代わって各圧力補償弁(8L,8R,8B)に作用す
るが、油圧ポンプ(1) は最大負荷圧(PLS3)を受けたまま
だからポンプ吐出圧(Pp)に変化はなく、従って各方向切
換弁(3L,3R,3B)の入口圧は「Pp」である。そこで上記
（Ａ）〜（ Ｃ）によれば、各方向切換弁(3L,3R,3B)を流
れる油量は、「PLS3−PLS'＝ΔＰ」とすれば、 方向切換
弁(3L,3R) を流れる油量は「（Pp−PLS3＋ΔＰ）1/2 」
に比例し、 他方、方向切換弁(3B)を流れる油量は「（Pp
−PLS3）1/2 」に比例する 。即ち従来技術での説明に合
わせて説明すれば、走行側の方向切換弁(3L,3R) の前後
差圧が従来よりもΔＰだけ大きくなり、その分だけ走行
側により多くの圧油が流れる。従って、走行の減速率を
小さく抑えることができる。According to the above configuration, the following functions and effects can be obtained.
Play a fruit. As described above, FIG. 1 and FIG.
The description will be made with reference to the element codes described above. First, before the above configuration
The step configuration ("-") is, for example, as shown in FIG.
In addition, downstream of each directional control valve (3L, 3R, 3B), a pressure compensating valve (8L,
8R, 8B) for conventional load sensing
3 shows a hydraulic circuit. That is, each hydraulic actuator (2L, 2R, 2B)
Regardless of the load pressure (PLS1, PLS2, PLS3) of each directional control valve
(3L, 3R, 3B) indicates the flow rate proportional to the opening area of each.
Supply to each hydraulic actuator (2L, 2R, 2B). Of course
Of course, such a proportional supply is
The total required flow rate of the actuator (2L, 2R, 2B) is hydraulic pump (1)
Below the maximum discharge flow rate and below the relief pressure
It is established at some point. Therefore, the invention of the present application
Pressure change in a multi-stage load sensing hydraulic circuit
Means (13, 14a, 14b, 23, etc.)
Replace compensating valve (8L, 8R, 8B) with completely different pressure compensating valve (8L, 8R, 8B)
The above is a feature of the present invention. And this
The feature of the invention is the latter-stage configuration. Details are as follows. (1) That is, by the pressure changing means (13, 14a, 14b, 23, etc.)
Reduce the maximum load pressure (PLS3) received by each pressure compensating valve (8L, 8R, 8B).
Pressure (PLS '), the step-down (PLS')
Acts on each pressure compensating valve (8L, 8R, 8B) instead of load pressure (PLS3)
You . The hydraulic pump (1) receives the maximum load pressure (PLS3).
Since then, there has been no change in the pump discharge pressure (Pp). That is, each direction
The inlet pressure of the switching valves (3L, 3R, 3B) is `` Pp '' and does not change.
No. (2) However, the pressure compensating valves (8L, 8R, 8B) are
Each pressure receiving direction of the pressure surface (each area is the same) and the hydraulic pressure to each
The following operation is performed based on the relationship. Note that a spring (8d)
There is no force as seen from the hydraulic pressure generated on the first to fourth pressure receiving surfaces.
Only close the check valve (8a)
A weak bias. Therefore, the spring (8d) and its urging force are
And ignore it in the following explanation. (A) Hydraulic actuator on the side other than the maximum load pressure (PLS3)
(2L) load compensating valve (8L) for load pressure (PLS1) has the following behavior
Is shown . That is, in the case of “PLS1 <PLS '”, the output of the directional control valve (3L)
The compensation piston (8c) reverses until the pressure (P1) drops to the pressure drop (PLS ').
Close the stop valve (8a) to narrow the flow path. Outlet pressure (P1) drops (PL
When the pressure rises to S ′), the check valve (8a) opens. I mean
The pressure compensating valve (8L) uses the load pressure (PLS1) oil as a hydraulic actuator.
(2L). Note that the step-down (PLS ') is assumed to be "PLS'<PLS1"
The load pressure (PLS1) reverses the compensation piston (8c).
Separate from the stop valve (8a), so that “P1 = PLS1”
The check valve (8a)
The pressure compensating valve (8L) opens and the hydraulic pressure load (PLS1) oil is hydraulically actuated.
Supply to tutor (2L). (B) Another hydraulic actuator on the side other than the maximum load pressure (PLS3)
Pressure compensating valve (8R) for tutor (2R) load pressure (PLS2)
Also conforms to the pressure compensating valve (8L). That is, "PLS2 <PL
S ''', the outlet pressure (P2) of the directional control valve (3R) decreases to the step-down pressure (PLS').
The compensation piston (8c) closes the check valve (8a) until
Squeeze. Non-return when the outlet pressure (P2) increases to the step-down (PLS ')
The valve (8a) is open. That is, the pressure compensating valve (8R)
LS2) oil is supplied to the hydraulic actuator (2R). In addition, step-down
If (PLS ') is set to "PLS'<PLS2", the load pressure (P
LS2) separates the compensation piston (8c) from the check valve (8a),
This results in “P2 = PLS2” (ie, the pressure compensation function
The check valve (8a) opens and the pressure compensating valve (8B)
The oil at the load pressure (PLS2) is supplied to the hydraulic actuator (2R). (C) However, the hydraulic actuator on the maximum load pressure (PLS3) side
The pressure compensating valve (8B) for the load pressure (PLS3) of the
Show movement. That is, the self-load pressure (PLS3) increases the compensation piston (8c).
Separate from the check valve (8a), and as a result, “P3 = PLS3”
Check valve (8a)
Opens, and the pressure compensating valve (8B) hydraulically applies the oil of the load pressure (PLS3).
Supply to couture (2B). (D) That is, by the pressure changing means (13, 14a, 14b, 23, etc.)
Reduce the maximum load pressure (PLS3) received by each pressure compensating valve (8L, 8R, 8B).
Pressure (PLS '), the step-down (PLS')
Acts on each pressure compensating valve (8L, 8R, 8B) instead of load pressure (PLS3)
However, the hydraulic pump (1) receives the maximum load pressure (PLS3)
Therefore, there is no change in the pump discharge pressure (Pp).
The inlet pressure of the switching valves (3L, 3R, 3B) is “Pp”. So above
According to (A) to ( C), each directional control valve (3L, 3R, 3B)
If the amount of oil to be set is “PLS3−PLS ′ = ΔP”, the direction is switched.
The amount of oil flowing through the valves (3L, 3R) is "(Pp-PLS3 + ΔP) 1/2"
The amount of oil flowing through the directional control valve (3B) is “(Pp
−PLS3) 1/2 ” . That is to say,
In other words, before and after the traveling side directional control valve (3L, 3R)
The differential pressure becomes larger by ΔP than before, and it travels by that much.
More pressure oil flows to the side. Therefore, the driving deceleration rate
It can be kept small .

【００１０】[0010]

【実施例】以下に本発明に係るロードセンシング油圧回
路の実施例について、図面を参照して説明する。なお、
図１は油圧式掘削機に用いられるロードセンシングシス
テムのうち、走行モータと、各作業機用アクチュエータ
のうちブームシリンダに関する油圧回路の概略構成を示
したもので、方向切換弁の詳細は本発明者がさきに出願
した特願平１−８２９６１の通りである。図１におい
て、ロードセンシングシステムは１個のポンプ１と、ポ
ンプ１が吐出する圧油によって駆動される左側駆動輪の
走行モータ２L 、右側駆動輪の走行モータ２R 、ブーム
シリンダ２B と、ポンプ１から前記走行モータ２L，２R
およびブームシリンダ２B に送られる圧油の方向を切り
換えるクローズドセンタの方向切換弁３L ，３R ，３B
と、ポンプ１が吐出する圧油の流量を制御するレギュレ
ータ４およびＬＳ弁５とを備えている。For the embodiment of Example Load Sensing grayed oil pressure circuit according to the present invention will now be described with reference to the accompanying drawings. In addition,
FIG. 1 shows a schematic configuration of a traveling motor and a hydraulic circuit relating to a boom cylinder among actuators for each work machine in a load sensing system used for a hydraulic excavator. It is as disclosed in Japanese Patent Application No. 1-82961 filed earlier. In FIG. 1, the load sensing system includes one pump 1, a traveling motor 2L for a left driving wheel, a traveling motor 2R for a right driving wheel, a boom cylinder 2B driven by pressure oil discharged from the pump 1, and a pump 1. The traveling motor 2L, 2R
And directional change-over valves 3L, 3R, 3B of a closed center for switching the direction of pressure oil sent to the boom cylinder 2B.
And a regulator 4 and an LS valve 5 for controlling the flow rate of the pressure oil discharged from the pump 1.

【００１１】前記方向切換弁３L，３R，３B は、ポンプ
１の吐出回路６から分岐する回路６L，６R，６B にそれ
ぞれ接続され、方向切換弁３L，３R，３B から走行モー
タ２L，２Rおよびブームシリンダ２B に至る回路７L，
７R，７B にそれぞれ圧力補償弁８L，８R，８B が設け
られている。各走行モータをはじめとする油圧アクチュ
エータの負荷圧は、それぞれパイロット回路９L，９R，
９B およびシャトル弁１０，１１等を経て、その最大値
ＰLSがパイロット回路１２を介してＬＳ弁５の一端に導
かれている。また、前記パイロット回路１２の分岐回路
１３に可変絞り１４ａが設けられ、前記アクチュエータ
負荷圧の最大値ＰLSは、可変絞り１４ａを経た後、それ
ぞれパイロット回路１５L，１５R，１５Bを介して圧力
補償弁８L，８R，８Bに導かれている。ＬＳ弁５の他端
は回路６から分岐したパイロッット回路１６に接続され
てポンプ１の吐出圧ＰP を受けている。The directional control valves 3L, 3R, 3B are respectively connected to circuits 6L, 6R, 6B branching from the discharge circuit 6 of the pump 1, and the directional control valves 3L, 3R, 3B pass through the traveling motors 2L, 2R and the boom. Circuit 7L leading to cylinder 2B,
7R and 7B are provided with pressure compensating valves 8L, 8R and 8B, respectively. The load pressures of the hydraulic actuators including the traveling motors are controlled by pilot circuits 9L, 9R,
The maximum value PLS is guided to one end of the LS valve 5 via the pilot circuit 12 via the 9B and the shuttle valves 10, 11 and the like. Further, a variable throttle 14a is provided in the branch circuit 13 of the pilot circuit 12, and the maximum value PLS of the actuator load pressure passes through the variable throttle 14a, and then, through the pilot circuits 15L, 15R, and 15B, the pressure compensating valve 8L. , 8R, 8B. The other end of the LS valve 5 is connected to a pilot circuit 16 branched from the circuit 6, and receives the discharge pressure PP of the pump 1.

【００１２】運転席近傍に設けられた走行レバー１７
L，１７R、ブームを駆動する操作レバー１７B は、それ
ぞれＰＰＣ弁１８L，１８R，１８B に連結され、これら
のＰＰＣ弁から出るパイロット回路１９L，１９R，１９
Bは、それぞれ方向切換弁３L，３R，３Bに接続されてい
る。また、前記パイロット圧を検出する圧力スイッチ２
０L，２０R，２０B の出力配線２１L，２１R，２１B
は、いずれもコントローラ２２に接続されている。A traveling lever 17 provided near the driver's seat
L, 17R, and an operating lever 17B for driving the boom are connected to PPC valves 18L, 18R, 18B, respectively, and pilot circuits 19L, 19R, 19B coming out of these PPC valves.
B is connected to the directional control valves 3L, 3R, 3B, respectively. A pressure switch 2 for detecting the pilot pressure
Output wiring 21L, 21R, 21B of 0L, 20R, 20B
Are connected to the controller 22.

【００１３】前記パイロット回路１５L の延長上に油タ
ンク１５ａに至る回路１５ｃが設けられ、この回路１５
ｃには可変絞り１４ｂと切換弁２３とが設置されてい
る。また、油圧ポンプ２４と前記切換弁２３の端部とを
結ぶパイロット回路２５に電磁弁２６が設けられ、電磁
弁２６のソレノイドには前記コントローラ２２の出力配
線２７が接続されている。A circuit 15c extending to the oil tank 15a is provided on an extension of the pilot circuit 15L.
In c, a variable throttle 14b and a switching valve 23 are installed. An electromagnetic valve 26 is provided in a pilot circuit 25 connecting the hydraulic pump 24 and an end of the switching valve 23, and an output wiring 27 of the controller 22 is connected to a solenoid of the electromagnetic valve 26.

【００１４】コントローラ２２は、ＰＰＣ弁１８L，１
８Rのパイロット圧を検出する圧力スイッチ２０L，２０
Rのいずれか一つ以上がＯＮとなり、かつＰＰＣ弁１８B
のパイロット圧を検出する圧力スイッチ２０B がＯＮと
なったとき、出力配線２７を介して電磁弁２６に指令電
流を出力する。The controller 22 includes a PPC valve 18L, 1
Pressure switches 20L, 20 for detecting 8R pilot pressure
R is turned on at least one of them and the PPC valve 18B
When the pressure switch 20B for detecting the pilot pressure is turned ON, a command current is output to the solenoid valve 26 via the output wiring 27.

【００１５】ＬＳ弁５に作用する負荷圧ＰLSに対して、
圧力補償弁８L，８R，８Bに作用する信号圧は、可変絞
り１４ａを経ることにより、ＰLSより低いＰLS′とな
る。なお可変絞り１４ｂは、切換弁２３が切換えられ、
パイロット回路１５L，１５R内の圧油が回路１５ｃを経
てドレンされる際に、圧力補償弁８L，８R，８Bに作用
する信号圧を一定値以上に維持するために設けられてい
る。With respect to the load pressure PLS acting on the LS valve 5,
The signal pressure acting on the pressure compensating valves 8L, 8R, 8B becomes PLS 'lower than PLS by passing through the variable throttle 14a. In the variable throttle 14b, the switching valve 23 is switched,
It is provided to maintain the signal pressure acting on the pressure compensating valves 8L, 8R, 8B at a certain value or more when the pressure oil in the pilot circuits 15L, 15R is drained through the circuit 15c.

【００１６】前記圧力補償弁８L，８R，８Bは図２に示
すように、弁本体内を摺動自在の逆止め弁８ａ、補償ピ
ストン８ｃ、ばね８ｄからなり、信号圧ＰLSは補償ピス
トン８ｃに設けられた穴８ｅからばね室８ｆ内に導かれ
ている。方向切換弁を通った圧油は通路８ｇから逆止め
弁８ａ内に入り、補償ピストン８ｃとばね８ｄとを図２
の右方に押してシート面を開き、アクチュエータポート
８ｈに流れる。今、信号圧をＰLSとすると補償ピストン
室８ｆの圧力もＰLSとなり、補償ピストン８ｃの径と逆
止弁８ａの径は等しいので逆止弁８ａの入口室８ｇの圧
力Ｐ1 はＰLSよりも戻しばね８ｄのばね力分だけ高くな
るが、ばね力は圧力ＰLSに対し充分弱いのでＰ1 ≒ＰLS
とみなすことができる。即ち圧力補償弁の入口圧（切換
えバルブの出口圧）は信号圧ＰLSにほぼ等しくなる。As shown in FIG. 2, the pressure compensating valves 8L, 8R and 8B comprise a check valve 8a slidable in the valve body, a compensating piston 8c and a spring 8d, and the signal pressure PLS is applied to the compensating piston 8c. It is led into the spring chamber 8f from the provided hole 8e. The pressure oil having passed through the directional control valve enters the check valve 8a from the passage 8g, and the compensating piston 8c and the spring 8d
To the right to open the seat surface and flow to the actuator port 8h. Now, pressures PLS next the compensation piston chamber 8f to the signal pressure and PLS, diameters of the check valves 8a of the compensating piston 8c pressure P 1 of the inlet chamber 8g of the check valve 8a is equal returns than PLS The spring force is increased by the spring force of the spring 8d, but the spring force is sufficiently weak against the pressure PLS, so that P 1 ≒ PLS
Can be considered. That is, the inlet pressure of the pressure compensating valve (the outlet pressure of the switching valve) becomes substantially equal to the signal pressure PLS.

【００１７】次に上記操作性向上油圧回路の動作につい
て説明する。油圧式掘削機が走行中にブームを駆動させ
ると、図１において前記圧力スイッチ２０L，２０R，２
０B がそれぞれＯＮとなり、コントローラ２２の指令電
流により電磁弁２６が励磁され、切換弁２３が切換えら
れる。アクチュエータ負荷圧の最大値ＰLSは、ブームシ
リンダ負荷圧ＰLS3であるから、 △Ｐ＝ＰLS3−ＰLS′＝ＰLS−ＰLS′ とすれば、各アクチュエータへの流量はそれぞれ下記の
式で表すことができる。 Ｑ1 ＝ｃ×Ａ1×（ＰP−Ｐ1）1/2 ≒ｃ×Ａ1×（ＰP−ＰLS′）1/2（理由；圧力補償弁の
特性による） ＝ｃ×Ａ1×（ＰP−ＰLS3＋△Ｐ）1/2 Ｑ2 ＝ｃ×Ａ2×（ＰP−Ｐ2）1/2 ≒ｃ×Ａ2×（ＰP−ＰLS′）1/2 ＝ｃ×Ａ2×（ＰP−ＰLS3＋△Ｐ）1/2 Ｑ3 ＝ｃ×Ａ3×（ＰP−Ｐ3）1/2 ≒ｃ×Ａ3×（ＰP−ＰLS3）1/2（理由；図２からわかる
様に、信号圧ＰLS′よりも負荷圧ＰLS3（８ｈ）が高い
時は補償ピストン８ｃは図の右端に押しつけられ圧力補
償弁はチェック弁として作用するので、最高圧となるブ
ーム回路はこの式で表される。） 従ってＱ1，Ｑ2は△Ｐだけ差圧が大きくなり、走行モー
タ２L，２Rに対する流量は従来より多くなる。圧力補償
弁８B では、ばね室８ｆに導かれ、補償ピストン８ｃに
作用する信号圧ＰLS′と、方向切換弁３B の出口圧Ｐ3
との関係が、Ｐ3 ≒ＰLS3 となって圧力補償機能がなく
なり、逆止め弁８ａのみが機能する。Next, the operation of the operability improving hydraulic circuit will be described. When the boom is driven while the hydraulic excavator is running, the pressure switches 20L, 20R, 2 in FIG.
0B is turned ON, the solenoid valve 26 is excited by the command current of the controller 22, and the switching valve 23 is switched. Since the maximum value PLS of the actuator load pressure is the boom cylinder load pressure PLS3, if ΔP = PLS3−PLS ′ = PLS−PLS ′, the flow rate to each actuator can be expressed by the following equations. Q1 = c × A1 × (PP-P1) 1/2 ≒ c × A1 × (PP-PLS ′) 1/2 (Reason: Depends on the characteristics of the pressure compensating valve) = c × A1 × (PP-PLS3 + △ P) 1/2 Q2 = c * A2 * (PP-P2) 1/2 @ c * A2 * (PP-PLS ') 1/2 = c * A2 * (PP-PLS3 + $ P) 1/2 Q3 = c * A3 × (PP-P3) 1/2 ≒ c × A3 × (PP-PLS3) 1/2 (Reason: As can be seen from FIG. 2, compensation is made when the load pressure PLS3 (8h) is higher than the signal pressure PLS '. Since the piston 8c is pressed to the right end of the drawing and the pressure compensating valve acts as a check valve, the boom circuit that has the highest pressure is represented by this equation.) Therefore, the differential pressure of Q1 and Q2 increases by ΔP, and the vehicle travels. The flow rate for the motors 2L and 2R is larger than before. In the pressure compensating valve 8B, the signal pressure PLS 'guided to the spring chamber 8f and acting on the compensating piston 8c and the outlet pressure P3 of the directional control valve 3B.
Is P3 ≒ PLS3, the pressure compensation function is lost, and only the check valve 8a functions.

【００１８】可変絞り１４ａ，１４ｂを調節すれば、圧
力補償弁８L，８Rの信号圧ＰLS′の大きさを変えること
ができるので、油圧掘削機の使用目的に合った最適流量
を走行側に供給することができる。また、可変絞り１４
ａ，１４ｂを固定絞りとしてもよい。By adjusting the variable throttles 14a and 14b, the magnitude of the signal pressure PLS 'of the pressure compensating valves 8L and 8R can be changed, so that an optimal flow rate suitable for the purpose of use of the hydraulic excavator is supplied to the traveling side. can do. In addition, the variable aperture 14
a and 14b may be fixed apertures.

【００１９】図３は、作業機操作レバー操作状態と、走
行モータに供給される圧油流量との関係を示したもので
ある。油圧式掘削機が走行していて、作業機たとえばブ
ームの操作レバーが中立位置にあるとき、走行モータに
供給される圧油流量は、走行レバーの操作量に応じた流
量であり、これを１００％とする。この状態でブーム操
作レバーをフルストロークに操作すると、切換弁がＯＦ
Ｆのときすなわち通常のロードセンシングシステムの場
合は、走行モータに供給される圧油流量が約５０％に減
少する。しかし切換弁がＯＮのときは、前記圧油流量が
７０〜８０％に保たれ、かつ作業機操作時の減速ショッ
クも小さい。FIG. 3 shows the relationship between the operating state of the work implement operating lever and the flow rate of hydraulic oil supplied to the traveling motor. When the hydraulic excavator is traveling and the operating lever of the working machine, for example, the boom is at the neutral position, the flow rate of the hydraulic oil supplied to the traveling motor is a flow rate corresponding to the operation amount of the traveling lever. %. When the boom operation lever is operated to the full stroke in this state, the switching valve is turned off.
In the case of F, that is, in the case of the ordinary load sensing system, the flow rate of the pressure oil supplied to the traveling motor is reduced to about 50%. However, when the switching valve is ON, the flow rate of the pressure oil is maintained at 70 to 80%, and the deceleration shock during operation of the work machine is small.

【００２０】本実施例では、アクチュエータ操作レバー
の操作を検出する手段として、ＰＰＣ弁のパイロット圧
を検出する圧力スイッチを用いたが、これに限るもので
はなく、アクチュエータ操作レバーのストロークが一定
値以上になったときに作動するリミットスイッチまたは
近接スイッチ等を用いてもよい。In this embodiment, the pressure switch for detecting the pilot pressure of the PPC valve is used as means for detecting the operation of the actuator operation lever. However, the present invention is not limited to this. For example, a limit switch or a proximity switch that is activated when the pressure becomes may be used.

【００２１】[0021]

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の基本構成を示す概略部分油圧回路図で
ある。FIG. 1 is a schematic partial hydraulic circuit diagram showing a basic configuration of the present invention.

【図２】圧力補償弁の断面図である。FIG. 2 is a sectional view of a pressure compensating valve.

【図３】走行中に作業機レバーを操作したときに、走行
モータに供給される圧油流量の変化を示す図である。FIG. 3 is a diagram illustrating a change in a flow rate of pressure oil supplied to a traveling motor when a work implement lever is operated during traveling.

【図４】従来のロードセンシングシステムを備えた油圧
駆動装置の基本構成を示す概略部分油圧回路図である。FIG. 4 is a schematic partial hydraulic circuit diagram showing a basic configuration of a hydraulic drive device including a conventional load sensing system.

【符号の説明】[Explanation of symbols]

１ 可変容量形油圧ポンプ ２L 左走行用油圧モータ ２R 右走行用油圧モータ ２B ブームシリンダ ３L，３R，３B 方向切換弁 ４ レギュレータ ５ ＬＳ弁 ６，６L，６R，６B，７L，７R，７B，１５ｃ 回路 ８L，８R，８B 圧力補償弁 ９L，９R，９B，１２，１５L，１５R，１５B，１６，１
９L，１９R， １９B， ２５ パイロット回路 １４ａ，１４ｂ 可変絞り １５ａ 油タンク １７L， １７R 走行レバー １７B ブームレバー ２０L，２０R，２０B 圧力スイッチ ２２ コントローラ ２３ 切換弁 ２６ 電磁弁1 Variable displacement hydraulic pump 2L Left traveling hydraulic motor 2R Right traveling hydraulic motor 2B Boom cylinder 3L, 3R, 3B Direction switching valve 4 Regulator 5 LS valve 6, 6L, 6R, 6B, 7L, 7R, 7B, 15c Circuit 8L, 8R, 8B Pressure compensating valve 9L, 9R, 9B, 12, 15L, 15R, 15B, 16, 1
9L, 19R, 19B, 25 Pilot circuit 14a, 14b Variable throttle 15a Oil tank 17L, 17R Travel lever 17B Boom lever 20L, 20R, 20B Pressure switch 22 Controller 23 Switching valve 26 Solenoid valve

Claims (1)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】 可変容量形油圧ポンプ(1) の吐出側に複
数の方向切換弁(3L,3R,3B)を並列接続し、かつ各方向切
換弁(3L,3R,3B)の下流側にそれぞれの油圧アクチュエー
タ(2L,2R,2B)を接続すると共に、各方向切換弁(3L,3R,3
B)とそれぞれの油圧アクチュエータ(2L,2R,2B)との間に
各油圧アクチュエータ(2L,2R,2B)の内の最大負荷圧(PLS
3)を受けてそれぞれの方向切換弁(3L,3R,3B)の出口圧(P
1,P2,P3)を最大負荷圧(PLS3)に一致させる圧力補償弁(8
L,8R,8B)をそれぞれ設け、かつ可変容量形油圧ポンプ
(1) が自己吐出圧(Pp)と最大負荷圧(PLS3)とを受けて自
己吐出圧(Pp)が最大負荷圧(PLS3)よりも所定圧だけ高く
なるように自己吐出量を可変制御するロードセンシング
油圧回路において、 各圧力補償弁(8L,8R,8B)が受ける最大負荷圧(PLS3)を降
圧(PLS')自在とする圧力変更手段(13,14a,14b,23等) を
設けると共に、 前記各圧力補償弁(8L,8R,8B)は、 それぞれの方向切換弁(3L,3R,3B)の出口圧(P1,P2,P3)を
開方向に受ける第１受圧面とそれぞれの油圧アクチュー
タ(2L,2R,2B)の負荷圧(PLS1,PLS2,PLS3)を閉方向に受け
る第２受圧面とを備える逆止め弁(8a)と 、それぞれの油圧アクチュータ(2L,2R,2B)の負荷圧(PLS1,
PLS2,PLS3)を逆止め弁(8a)から離間させる方向に受ける
第３受圧面と最大負荷圧(PLS3)又は降圧(PLS')を逆止め
弁(8a)の閉方向に受ける第４受圧面と逆止め弁(8a)を閉
方向に軽く付勢する弱いバネ(8d)とを備える圧力補償ピ
ストン(8c)とを備え、かつ第１〜第４受圧面の各面積を
同じくしてある ことを特徴とするロードセンシング油圧
回路。 1. A discharge pump of a variable displacement hydraulic pump (1)
Number of directional control valves (3L, 3R, 3B) connected in parallel and
Each hydraulic actuator is located downstream of the replacement valve (3L, 3R, 3B).
(2L, 2R, 2B) and each directional control valve (3L, 3R, 3B)
B) and each hydraulic actuator (2L, 2R, 2B)
Maximum load pressure (PLS) of each hydraulic actuator (2L, 2R, 2B)
3), the outlet pressure (P) of each directional control valve (3L, 3R, 3B)
1, P2, P3) to the maximum load pressure (PLS3).
L, 8R, 8B) and a variable displacement hydraulic pump
(1) receives the self discharge pressure (Pp) and the maximum load pressure (PLS3) and
Self discharge pressure (Pp) is higher than maximum load pressure (PLS3) by a specified pressure
Load sensing that variably controls the self-discharge amount so that
In the hydraulic circuit, reduce the maximum load pressure (PLS3) received by each pressure compensation valve (8L, 8R, 8B).
Pressure (PLS ') free pressure changing means (13, 14a, 14b, 23, etc.)
At the same time, each of the pressure compensating valves (8L, 8R, 8B) controls the outlet pressure (P1, P2, P3) of the respective directional control valve (3L, 3R, 3B).
The first pressure receiving surface received in the opening direction and the respective hydraulic actuators
Load pressure (PLS1, PLS2, PLS3) of the motor (2L, 2R, 2B) in the closing direction.
Check valve (8a) having a second pressure receiving surface, and load pressures (PLS1, PLS1) of respective hydraulic actuators (2L, 2R, 2B).
(PLS2, PLS3) in the direction away from the check valve (8a)
Check the third pressure receiving surface and maximum load pressure (PLS3) or step-down (PLS ') back
Close the fourth pressure receiving surface received in the closing direction of the valve (8a) and the check valve (8a)
Pressure compensating pin with a weak spring (8d) that gently biases
And the respective areas of the first to fourth pressure receiving surfaces are provided.
Load Sensing grayed oil pressure circuit, wherein you have also.
JP3075708A 1991-03-15 1991-03-15 Load sensing hydraulic circuit Expired - Fee Related JP3006777B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP3075708A JP3006777B2 (en) 1991-03-15 1991-03-15 Load sensing hydraulic circuit
PCT/JP1992/000268 WO1992016754A1 (en) 1991-03-15 1992-03-06 Hydraulic circuit improved in operability in load sensing system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3075708A JP3006777B2 (en) 1991-03-15 1991-03-15 Load sensing hydraulic circuit

Publications (2)

Publication Number Publication Date
JPH04285303A JPH04285303A (en) 1992-10-09
JP3006777B2 true JP3006777B2 (en) 2000-02-07

Family

ID=13583998

Family Applications (1)

Application Number Title Priority Date Filing Date
JP3075708A Expired - Fee Related JP3006777B2 (en) 1991-03-15 1991-03-15 Load sensing hydraulic circuit

Country Status (2)

Country Link
JP (1) JP3006777B2 (en)
WO (1) WO1992016754A1 (en)

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* Cited by examiner, † Cited by third party
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CN104709834A (en) * 2013-12-11 2015-06-17 北汽福田汽车股份有限公司 Revolution speed regulation control system and crane

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GB2436311B (en) * 2006-03-22 2008-04-09 Textron Fastening Syst Ltd Improved hydraulic damper valve
CN102140808B (en) * 2011-01-11 2012-05-23 徐州徐工挖掘机械有限公司 Device for enhancing excavation-handling characteristics and levelling operation characteristics of excavator
CN102400966B (en) * 2011-09-29 2014-09-17 徐州重型机械有限公司 Loading and unloading switching device and oil supply system and engineering machinery applying same
CN107458459A (en) * 2017-07-20 2017-12-12 郭向阳 Walking steer-drive and its control method
CN112833058B (en) * 2021-01-21 2023-03-31 长沙中联重科环境产业有限公司 Load-sensitive hydraulic system and hedge trimming equipment

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Publication number Priority date Publication date Assignee Title
DE3044144A1 (en) * 1980-11-24 1982-09-09 Linde Ag, 6200 Wiesbaden HYDROSTATIC DRIVE SYSTEM WITH ONE ADJUSTABLE PUMP AND SEVERAL CONSUMERS
JPS61206804A (en) * 1985-03-08 1986-09-13 Kawasaki Heavy Ind Ltd Parallel multibranch hydraulic circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104709834A (en) * 2013-12-11 2015-06-17 北汽福田汽车股份有限公司 Revolution speed regulation control system and crane

Also Published As

Publication number Publication date
JPH04285303A (en) 1992-10-09
WO1992016754A1 (en) 1992-10-01

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