REXROTH液控单向阀SL20PA1-4X

REXROTH液控单向阀SL20PA1-4X，武汉百士自动化设备有限公司供应产品，现货库存，原厂原装，质量保障，价格优惠；移动电话：15307180902，商务QQ：980227448，传真：027-87680708-608，联系人：雷青；欢迎新老客户咨询购买！

液控单向阀是方向控制阀中的一种。具体分类：

方向控制阀按其在液压系统中的功能分为单向阀和换向阀两大类。

单向阀在液压传动中有普通单向阀和液控单向阀。

(1)保持压力。

滑阀式换向阀都有间隙泄漏现象，只能短时间保压。当有保压要求时，可在油路上加一个液控单向阀，利用锥阀关闭的严密性，使油路长时间保压。

(2)液压缸的“支承”。

在立式液压缸中，由于滑阀和管的泄漏，在活塞和活塞杆的重力下，可能引起活塞和活塞杆下滑。将液控单向阀接于液压缸下腔的油路，则可防止液压缸活塞和滑块等活动部分下滑。

(3)实现液压缸锁紧。

当换向阀处于中位时，两个液控单向阀关闭，可严密封闭液压缸两腔的油液，这时活塞就不能因外力作用而产生移动。

(4)大流量排油。

液压缸两腔的有效工作面积相差很大。在活塞退回时，液压缸右腔排油量骤然增大，此时若采用小流量的滑阀，会产生节流作用，限制活塞的后退速度；若加设液控单向阀，在液压缸活塞后退时，控制压力油将液控单向阀打开，便可以顺利地将右腔油液排出。

(5)作充油阀。

立式液压缸的活塞在高速下降过程中，因高压油和自重的作用，致使下降迅速，产生吸空和负压，必须增设补油装置。液控单向阀作为充油阀使用，以完成补油功能。

(6)组合成换向阀。

在设计液压回路时，有时可将液控单向阀组合成换向阀使用。例如：用两个液控单向阀和一个单向阀并联（单向阀居中），则相当于一个三位三通换向阀的换向回路。需要指出，控制压力油油口不工作时，应使其通回油箱，否则控制活塞难以复位，单向阀反向不能截止液流。

REXROTH液控单向阀SL20PA1-4X

力士乐REXROTH液控单向阀SV 6

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力士乐液控单向阀SV 10...32

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力士乐REXROTH液控单向阀SL 6

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液压传动系统的组成

1、液压动力原件

将动力装置的机械能转换成为液压能的装置，其作用是为液压传动系统提供压力油,是液压传动系统的动力源。例如液压泵。

1.1液压泵

液压泵是液压系统的动力元件，其作用是将原动机的机械能转换成液体的压力能,指液压系统中的油泵，它向整个液压系统提供动力。液压泵的结构形式一般有齿轮泵、叶片泵和柱塞泵。

1.2齿轮泵

齿轮泵即依靠密封在个壳体中的两个或两个以上齿轮,在相互啮合过程中所产生的工作空间容积变化来输送液体的泵。齿轮泵的概念是很简单的，即它的最基本形式就是两个尺寸相同的齿轮在一个紧密配合的壳体内相互啮合旋转，这个壳体的内部类似“8”字形，两个齿轮装在里面,齿轮的外径及两侧与壳体紧密配合。来自于挤出机的物料在吸入口进入两个齿轮中间，并充满这一空间，随着齿的旋转沿壳体运动，最后在两齿啮合时排出。困油现象齿轮泵要平稳工作，齿轮啮合的重合度必须大于1, 于是总有两对齿轮同时啮合, :并有一部分油液被围困在两对轮齿所围成的封闭容腔之间。这个封闭的容腔开始随着

齿轮的转动逐渐减小，以后又逐渐加大。封闭腔容积的减小会使被困油液受挤压而产生很高的压力，并且从缝隙中挤出，导致油液发热，并致使机件受到额外的负载，而封闭腔容积的增大又造成局部真空，使油液中溶解的气体分离，产生气穴现象。这些都将产生强烈的振动和噪音，这就是齿轮泵的困意现象。

危害：径向不平衡力很大时能使轴弯曲，齿顶与壳体接触，同时加速轴承的磨损，降低轴承的寿命。

消除困油现象方法:通常是在两侧盖板上开卸荷槽，使封闭腔容积诚小时通过左边的卸荷槽与压油腔相通，容积增大时通过右边的卸荷槽与吸油腔相通。

1.3叶片泵

叶片泵即通过叶轮的旋转，将动力机的机械能转换为水能(势能、动能、压能)的水力机械。

叶片泵转子旋转时，叶片在离心力和压力油的作用下，尖部紧贴在定子内表面上。这样两个叶片与转子和定子内表面所构成的工作容积，先由小到大吸油后再由大到小排油，叶片旋转一周时，完成两次吸油与排油。

1.4柱塞泵

柱塞泵即利用柱塞在泵缸体内往复运动，使柱塞与泵壁间形成容积改变，反复吸入和排;出液体并增高其压力的泵。

柱塞泵是液压系统的一个重要装置。它依靠柱塞在缸体中往复运动，使密封工作容腔的容积发生变化来实现吸油、压油。柱塞泵具有额定压力高、结构紧凑、效率高和流量调节方便等优点，被广泛应用于高压、大流量和流量需要调节的场合，诸如液压机、工程机械和船舶中。