CN1163673C - 液压系统和液压阀机构 - Google Patents

液压系统和液压阀机构 Download PDF

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CN1163673C
CN1163673C CNB981215491A CN98121549A CN1163673C CN 1163673 C CN1163673 C CN 1163673C CN B981215491 A CNB981215491 A CN B981215491A CN 98121549 A CN98121549 A CN 98121549A CN 1163673 C CN1163673 C CN 1163673C
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pressure
pump
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CN1215809A (zh
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劳德・A・维尔克
劳德·A·维尔克
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Husco International Inc
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/06—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with two or more servomotors
    • 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
    • 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
    • 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
    • F15B13/026—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
    • 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
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • F15B2211/3053—In combination with a pressure compensating valve
    • F15B2211/30555—Inlet and outlet of the pressure compensating valve being connected to the 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
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple 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
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed centre
    • 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
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3144—Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional 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
    • F15B2211/35—Directional control combined with flow 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40553—Flow control characterised by the type of flow control means or valve with 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/465—Flow control with 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/87169—Supply and exhaust
    • Y10T137/87177—With bypass
    • Y10T137/87185—Controlled by supply or exhaust valve

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Multiple-Way Valves (AREA)

Abstract

一种液压系统，具有控制液压流体从一泵流到多个致动器的一组阀部件，各阀部件有一与一个致动器连接的控制口和一具有测流口的阀柱，测流口调节液压流体从泵流到致动器的流量。阀部件具有位于一孔腔中的一提升阀芯和一阀件，以构成在提升阀芯一侧的第一腔室、在阀件一侧的第二腔室和在提升阀芯与阀件之间的中间腔室，提升阀芯和阀件被一弹簧加压分开，第一腔室连接于测流口，第二腔室连接于泵控制输入端，中间腔室与孔腔的一输出口连通，液压流体通过输出口流到致动器，孔腔具有一接纳取决于泵输出压力的压力的输入口；孔腔内的提升阀芯的运动控制在第一腔室与输出口之间的液压流体的流量，孔腔内的阀件的运动控制从泵到第二腔室的输出压力的传送。

Description

液压系统和液压阀机构
(1)技术领域
本发明涉及一种液压系统和一种液压阀机构。
(2)背景技术
一台机器上液压从动工件的速度取决于液压系统主要狭孔的横截面积，以及通过那些狭孔的压降。为了便于控制，已设计了压力补偿液压控制系统来设定和保持压降。这些早先的控制系统包括将阀门工作口处的压力传递到变量液压泵上的输入端以在系统中提供增压液压流体的检测线路。泵输出产生的自我调节提供了一大致恒定的穿过控制孔口的压降，可由机器的操作人员控制该控制孔口的横截面积。因为压降保持恒定，工件的运动速度仅由该孔口的横截面积决定，所以便于控制。发明名称为“后继压力补偿的整体液压阀”的美国专利第4,693,272号公开了这样一种系统，在此援引其公开内容作为参考。
由于在这种系统中的控制阀和液压泵通常不能相互毗邻地设置，所以，必须通过软管或其他相对较长的导管将变负荷压力的信息传递到较远的泵输入端。当机器停止工作处于中间状态时，一些液压流体往往会从这些导管中流出。当操作人员要求再次运行时，在压力补偿系统充分生效前，必须将这些导管再次注满。由于这些导管的长度，泵的响应可能会滞后，并且可能发生负荷的轻微下降，这些特征被称作“时间滞后”和“起动下降”问题。
在某些类型的液压系统中，驱动负荷的活塞“达最低点(bottoming out)”可能引起整个系统“中止操作”。这种情况可能发生于使用最大工作口压力来推动压力补偿系统的系统中。在这种情况下，达最低点的负荷具有最大的工作口压力，且泵不能提供较大的压力；因此通过控制孔口不会有一个压降。作为一种补救，这种系统可以在液压控制系统的负荷检测环路内包括一个减压阀。达最低点状态时，打开减压阀使检测到的压力下降至负荷检测下降压力，使泵能够提供一通过控制孔口的压降。
当这种措施有效时，在使用压力补偿止回阀作为保持通过控制孔口压降基本恒定的系统中，会产生不希望有的副作用。即使工作口压力超过负荷检测减压阀的设定点，活塞没有达最低点，减压阀仍可能会打开。在这种情况下，某些流体将从工作口向后流过压力补偿止回阀进入泵腔室内。结果，负荷可能下降，这种情况可被称为“回流”问题。
已有压力补偿液压控制系统的另一个缺陷是大量的元件。例如，美国专利第5,579,642号描述的系统提供了检测在各个阀部件的每一个动力工作孔口的压力的一系列往复阀。根据检测到的工作口压力，该一系列往复阀的输出压力施加到将泵的控制输入端连接到泵输出端或储存罐的隔离阀。这就要求简化压力补偿液压控制系统的结构和降低制造的复杂性。
(3)发明内容
本发明的目的是提供一种液压系统和一种液压阀机构，它们的结构较现有技术中的压力补偿液压控制系统简单，由此减少了制造的复杂性，同时又克服了现有技术中所存在的“时间滞后”和“起动下降”的问题。
一用来将液压流体送入多个致动器的液压阀组件包括：一产生可变输出压力的泵，这个输出压力在任何时候都等于泵控制输入端的输入压力和一恒定裕量压力(margin pressure)之和。控制液压流体从泵流到一不同的致动器的一单独的阀部件承受作用在产生一液压负荷压力的致动器上的负荷力。阀部件的类型使得最大的液压负荷压力被检测，并用于控制传递到泵控制输入口的负荷检测压力。
每个阀部件具有一可变的测流口，通过这个孔液压流体从泵进入相关的致动器。从而泵输出端压力作用于测流口的一侧。每个阀部件内的压力补偿阀在测流口的另一侧提供负荷检测压力，使得通过测流口的压降基本上等于恒定的压力裕量。压力补偿器具有可在孔腔内滑动并被一弹簧加压分开的一阀柱和一阀件。阀柱和阀件构成了在孔腔相对两端的第一腔室和第二腔室和在两腔室之间的中间腔室。第一腔室与测流口的另一侧连通，而第二腔室与泵控制输入端连通。孔腔具有一输出口，流体从这里流向相应的液压致动器，中间腔室与输出口连通，以接纳液压负荷压力。孔腔的入口接纳来自泵的输出压力。
在第一腔室与中间腔室之间的第一压差和弹簧施加的力决定了提升阀芯在孔腔内的位置。提升阀芯的位置构成了通过在第一腔室与输出口之间的孔腔的通道尺寸，因此液压流体流到致动器。具体地说，第一腔室中比中间腔室要大的压力加大了输出口的尺寸，而中间腔室中比第一腔室要大的压力减小了输出口尺寸。因此，当来自负荷的反压力超过泵供应压力时，提升阀芯起到了防止流体从致动器通过阀部件流到泵的止回阀的作用。
在第二腔室与中间腔室之间的的第二压差和弹簧施加的力决定了阀件在孔腔内的位置。其位置控制了孔腔入口与泵控制输入端之间的连通，并因此控制了泵输出压力到泵控制输入端的传输。具体地说，第二腔室中比中间腔室要大的压力激励阀件减小孔腔入口与泵控制输入端之间的连通，而中间腔室中比第一腔室要大的压力激励阀件去增加在孔腔入口与泵控制输入口之间的连通。结果，施加压力，以控制直接从压力补偿阀获得的变量液压泵，而不需要如在以前阀组件中的单独一系列往复阀和一隔离阀。
(4)附图说明
图1是一液压系统的示意图，它具有一采用本发明新颖的压力补偿器的多阀组件；
图2是一穿过图1中多阀组件的一个部件的剖视图，它示意性地示出了与液压缸的连接；
图3-6是穿过一阀部件的一部分的剖视图，它示出了在不同工作状态下的补偿阀；以及
图7示出了本发明多阀组件的第二实施例。
(5)具体实施方式
图1示意地表示具有控制机器的液压动力工件诸如反向铲的悬臂和铲斗的动作的一多阀组件12的一液压系统10。阀组件12的具体结构包括几个相互并排在两端部件16与17之间的各个阀部件13、14和15。某一阀部件13、14或15控制从泵18流出的液压流体使之流入与工件连接的几个致动器20中的一个，然后控制流体再返回到一储存罐或容器19内。泵18的输出端由一减压阀11保护。每个致动器20都有一圆柱体外壳22，在外壳内有一个将外壳的内部分隔成下腔室26和上腔室28的活塞24。这里提到方向关系和运动，诸如顶和底或上和下，是指各元件在图所示方向中的关系和运动，可以不是连接到机器上一工件的构件的方向。
典型地，泵18是远离阀组件12的，并且通过供给导管或软管30连接到通过阀组件12的供给通道31。泵18是其输出压力被设计成等于排量控制口32的压力加上称作“裕量”的恒压的变量型泵。控制口32与穿过阀组件12的阀部件13-15的输送通道34连接。一储存罐通道36也穿过阀组件12并与容器19联接。阀组件12的端部部件16包含将供应通道31连接到泵18、将储存罐通道36连接到容器19和将输送通道34连接到泵18的控制孔口32的诸孔口。该端部部件16还包括降低连接到储存罐19的泵控制输送通道34中的过大压力的减压阀35。一孔口37提供一在输送通道34与容器19之间的流动路径，其功能将在下面描述。
为了便于理解在此所保护的本发明，有必要在所示的实施例中，说明有关一个阀部件14的流体基本的流动路径。其它阀部件13和15都以类同于阀部件14的方式运行，下面的说明也可应用于它们。
请参阅图2，阀部件14具有一个本体40和控制阀柱42，机器操作人员可以通过操作一固定在控制阀柱上的控制件(图中未示)，使控制阀柱42在本体内的一孔腔中沿着往复方向运动。根据控制阀柱42的运动方向，液压流体流向圆柱体外壳22的下腔室26或上腔室28，并籍此驱动活塞24分别向上或向下。机器操作人员移动控制阀柱42的程度决定了活塞24的速度以及连接于活塞的工件的速度。
为了降低活塞24，机器操作人员将往复式控制阀柱42向右移动到图2所示的位置。这样打开通道，允许泵18(在下文说明的负荷传感网络的控制下)把液压流体从容器19中抽吸出来，并迫使它流经泵输出导管30进入本体40内的供给通道31。液压流体从供给通道31通过由控制阀柱42的一组凹槽44形成的一测流口，再通过进给通道43和由在压力补偿止回阀48与本体40中的一开口之间的相对位置形成的可变孔口46(见图1)到分流通道50。在压力补偿止回阀48处于打开状态时，液压流体流过分流通道50，控制阀柱42的通道53，然后再通过工作口通道52，流出工作口54进入圆柱体外壳22的上腔室28。从而传递到活塞24顶部的压力使活塞向下运动，这样就迫使液压流体流出圆柱形外壳22的下腔室26。这被推出的液压流体流入另一个阀组件工作口56内，流经工作口通道58，通过通道59流经控制阀柱42以及与容器19相连的储存罐通道36。
为了向上移动活塞24，机器操作人员向左移动控制阀柱42，这样就打开了一套相应的通道，使泵18迫使液压流体进入下腔室26，并将流体推出圆柱体外壳22的上腔室28，使活塞向上移动。
如果没有压力补偿机构，机器操作人员将很难控制活塞24的速度。造成活塞的运动速度难以控制的直接原因是液压流体流速，而流速主要由两个变量决定，即流动路径中节流最甚的孔口横截面积和穿过这些孔口的压降。节流最甚的孔口之一是控制阀柱42的测流量的孔口44，而机器操作人员能够通过移动控制阀柱控制测流口口的横截面积。虽然这种方式能够控制一个有助于确定流速的变量，但是由于流速直接与系统内的总压降平方根成正比，而总压降主要在通过控制阀柱42的测量孔口44时发生，所以它仍不能提供最佳控制。例如，向反铲的铲斗添加材料可能增加圆柱体外壳下腔室26内的压力，这将减小负荷压力与泵18提供的压力之间的差值。没有压力补偿，这种总压降的减小将降低流速，从而，即使机器操作人员使测流口44保持一恒定的横截面积，仍将降低活塞24的速度。
本发明涉及一种以每个阀部件13-15内的一独立阀48为基础的压力补偿机构。参考图1-3，压力补偿阀48具有一提升阀芯60和一阀件64，它们两个在阀本体40的孔腔62内可密封地往复滑动。提升阀芯60和阀件64将孔腔62分隔成在孔腔62相对两端的可变容积的第一腔室65和第二腔室66以及在两腔室之间的中间腔室67，如图3所示。与孔腔端壁61相邻的第一腔室65与进给通道43连通，而第二腔室66与连接于泵控制口32的负荷检测输送通道34连通。
提升阀芯60相对于孔腔62的构成第一腔室65的端部不偏置，阀件64相对于孔腔的构成第二腔室66的端部不偏置。在此所用的“不偏置”指没有机械装置，诸如将力施加到提升阀芯或阀件上，由此激励构件离开孔腔各端部的弹簧。如将要描述的，没有这样一种偏置装置，导致只有第一腔室65内的压力来激励提升阀芯60离开孔腔62的相邻端部，只有第二腔室66内的压力激励阀件64离开相对的孔腔端部。
提升阀芯60有一带一开口端和一封闭端的管状部68，一直径缩小的止动轴70从封闭端延伸，以在图1、3和4所示的状态下撞击端壁61。管状部68有一横向小孔72，无论提升阀芯60的位置如何，该小孔使管状部68的内部(即中间腔室67)与在输出口69连接于孔腔(也可看图5和6)的分流通道50之间保持连通。
阀件64有一管状部74，其开口端面对提升阀芯60的开口端。一在管状部68和74内的相对较弱的弹簧76加偏压于提升阀芯60和阀件64，使它们分开。阀件64的管状部74外表面有一凹槽80。当阀件64邻接关闭孔腔62的一螺塞82时，凹槽80在负荷检测输送通道34与连接于来自于泵18的供应通道31部分的孔腔输入口83之间提供一流体通道。当阀件64明显地离开螺塞82，这流体通道被关闭，见图4。
图3-6示出了提升阀芯60和阀件64的四个工作状态。当在所有的阀部件中的控制阀柱42处在中立(即中心)位置时，出现图3和5中的状态。在阀部件14的测流口被关闭的情况下，供应通道31与进给通道43不通。控制阀柱的位置也使分流通道50连接于容器19。因此，提升阀芯60通过弹簧76被迫对着孔腔端壁61。当所有阀部件中的阀件64关闭时，负荷检测输送通道34内的流体通过端板16中的排放孔37放出，如图1所示，直到负荷检测压力等于容器压力。
在正常的工作中，当使用者移动阀柱42，将液压流体供应到工作口54或56之一时，进给通道43中的压力迫使提升阀芯60离开孔腔端壁61，并在进给通道43与分流通道50之间形成一流动通道，如图5和6所示。液压流体流过该通道到所选定的工作口。由于阀件64顶部的表面面积基本上与提升阀芯60底部的相同，液流在可变孔口46被节流，所以补偿阀48的第一腔室65中的压力大约等于在第二腔室66中的最大工作口压力。该压力通过图2中的进给通道43，与测流口44的一侧连通。测流口44的另一侧与接纳等于最大工作口压力加上恒定裕量压力的泵输出压力的供应通道31连通。结果，通过测流口44的压力降等于裕量压力。可以在测流口44的输出侧(通道31)和压力补偿止回阀48的第一腔室65看到最大工作口压力的变化。对于这种变化的反作用，提升阀芯60和阀件64寻找在孔腔62中维持通过测流口44的裕量压力的平衡位置。
当工作口压力大于进给通道43中的供应压力时，提升阀芯60起到一个避免液压流体被迫朝后从致动器20通过阀部件14到泵18的止回阀的作用。这个作用一般相对于非干线(off-highway)设备称为“起吊”(craning)，当一重的负荷施加到有关的致动器20时，这就发生了。这现象发生时，过量的负荷压力出现在分流通道50中，并通过在提升阀芯60中的横向小孔72与在提升阀芯和阀件64之间的中间空腔67连通。由于在中间腔室67中所产生的压力大于在进给通道43中的压力，迫使提升阀芯60抵靠着孔腔端壁61，如图1、3和4所示，由此关闭进给通道43与在孔腔输出口69处的分流通道50之间的连通。通过颠倒引起它的过程，例如除去致动器上的过量负荷，可终止起吊状况。
阀件64是检测多阀组件12中阀部件13-15的每一动力工作孔口压力的一机构的一零件，并响应施加到液压泵18的排量控制孔口32的压力变化。如图3和6所示，分流通道50的压力通过提升阀芯60的横向小孔72施加到在提升阀芯与阀件64之间的中间腔室67，由此到达阀件64的一侧。分流通道50和中间腔室承受被驱动的各个阀部件的工作孔口54或56处的压力，或当控制阀柱42在中间位置时储存罐通道36的压力。负荷检测输送通道34中的压力施加到阀件64的另一侧。当分流通道压力比负荷检测输送通道34的压力(即阀部件14有最大工作孔口压力)大时，激励阀件64朝螺塞82移动，使得凹槽80与负荷检测输送通道和泵供应通道31连通。在这个位置上，由凹槽80提供的可变孔所调节的泵输出压力通过负荷检测输送通道34传递到液压泵18的控制输入口32。
当阀部件14中的工作孔口压力下降到负荷检测压力之下时，激励阀件64离开螺塞82如图4和5所示。当另一阀部件有一较大的工作孔口压力时，这也可能发生。阀件64的这种运动关闭了负荷检测输送通道34与在先前通过凹槽80提供的孔腔入口的泵供应通道31之间的连通。
图7示出了一具有本发明的多阀组件88的第二种形式的液压系统86。各部分的标号类似于图1-6的第一实施例中的那些部分的标号。第二种多阀组件88的不同之处仅在于压力补偿阀48的的孔腔人口83通过通道90连接于进给通道43，而不是直接连接于泵供应通道31。阀件64以基本上与前面描述控制从泵输出的压力施加到泵18的控制输入的相同方式运行。该作用响应在阀部件13-15的每一个的工作孔口压力，并对泵压力进行类似的控制。

Claims (6)

1.一液压系统，它具有控制液压流体从一泵流到多个致动器的一组阀部件，该泵产生一随控制输入端压力而变化的输出压力，每一阀部件有一与一个致动器连接的控制口和一具有测流口的阀柱，该测流口是可变的以调节液压流体从泵流到致动器的流量；其改进之处包括：
每一个阀部件具有位于一孔腔中的一提升阀芯和一阀件，由此构成在提升阀芯一侧的第一腔室、在阀件一侧的第二腔室和在提升阀芯与阀件之间的中间腔室，提升阀芯和阀件被一弹簧所加压分开，第一腔室连接于测流口，第二腔室连接于泵控制输入端，中间腔室与该孔腔的一输出口连通，而液压流体通过该输出口流到致动器，该孔腔具有一接纳取决于泵输出压力的压力的输入口；以及
其中孔腔内的提升阀芯的运动控制在第一腔室与输出口之间的液压流体的流量，孔腔内的阀件的运动控制从泵到第二腔室的输出压力的传送。
2.如权利要求1所述的液压系统，还包括将泵的控制输入端连接于泵的流体储存罐的放出孔。
3.如权利要求1所述的液压系统，其特征在于，提升阀芯和阀件相对于孔腔没有加压偏置。
4.如权利要求1所述的液压系统，其特征在于，
阀柱有一具有一开口端和一封闭端的管状部；以及
阀件有一具有一封闭端和一开口端的管状部，其中该管状部面对前述的管状部。
5.如权利要求4所述的液压系统，其特征在于，提升阀芯具有从管状部的封闭端朝外延伸进入第一腔室的止动轴。
6.如权利要求4所述的液压系统，其特征在于，提升阀芯的管状部有一横向小孔，无论提升阀芯在孔腔内怎样运动，该小孔使输出孔口与中间腔室之间保持持续连通。
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CA2250674A1 (en) 1999-04-23
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EP0911529A2 (en) 1999-04-28
JPH11210705A (ja) 1999-08-03
KR100296238B1 (ko) 2001-08-07
US5890362A (en) 1999-04-06
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JP3298623B2 (ja) 2002-07-02
BR9804036A (pt) 1999-12-14

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