原文：
            溢流阀的用途 定压溢流作用：在定量泵节流调节系统中，定量泵提供的是恒定流量。当系统压力增大时，会使流量需求减小。此时溢流阀开启，使多余流量溢回油箱，保证溢流阀进口压力，即泵出口压力恒定（阀口常随压力波动开启）。 安全保护作用：系统正常工作时，阀门关闭。只有负载超过规定的极限（系统压力超过调定压力）时开启溢流，进行过载保护，闸阀使系统压力不再增加（通常使溢流阀的调定压力比系统最高工作压力高10％～20％）。 作卸荷阀用 作远程调压阀 作高低压多级控制阀 作顺序阀 用于产生背压（串在回油路上）。 1、直动型溢流阀 1）、锥阀式直动型溢流阀 锥阀式直动型溢流阀 图示为锥阀式直动型溢流阀。锥阀2的左端设有偏流盘1托住弹压弹簧5，锥阀右端有一阻尼活塞3（阻尼活塞一方面在锥阀开启或闭合时起阻尼作用，用来提高锥阀工作的稳定性；另一方面用来保证锥阀开启后不会倾斜）。进口的压力油（压力为P）可以由此活塞的径向间隙进入活塞底部，形成一个向左的液压力F=P·A（A为活塞底部面积）。当作用在底部的液压力F大于弹簧力时，锥阀阀口打开，油液由锥阀口经回流口溢回油箱。只要阀口打开，有油液流经溢流阀，溢流阀入口的压力就基本保持恒定。通过调节杆4来改变调压弹簧5的预紧力Ft，即可调整溢流压力。

　　锥阀开启后，（5－21） 　　式中，K、X0分别为弹簧刚度和预压缩量（m）；蝶阀G为阀芯自重（阀芯垂直安放时考虑自重，水平安放时不考虑自重）（N）；Ff为阀芯与阀套间的摩擦力（方向与阀芯运动的方向相反）（N）；F5为稳态液动力，由于阻尼活塞与锥阀连接处为锥面，且与锥阀对称，因此在锥阀开启时进油流与出油流的稳态液动力相互平衡，所以F5=0；Fj为射流力，在锥阀端部的偏流盘上开有一个环形槽，用以改变锥阀出流口的液流方向，产生一个与弹簧力方向相反的射流力，当通过溢流阀的流量增加时，虽然因为锥阀阀口增大引起弹簧力增加，但由于与弹簧力方向相反的射流力同时增加，结果抵消了弹簧力的增量，即。

 　　考虑到F5=0和Fj=Kx，则式（5－21）变成 （5－22） 　　由式（5－22）可知，这种阀的进口压力P不受流量变化的影响，即P不受阀口开度x大小的影响。被控压力P变化很小，定压精度高。 2）、球阀式直动型溢流阀 球阀式直动型溢流阀 图示为球阀式直动型溢流阀。它也有一个阻尼活塞3，但与锥阀式结构不同，活塞与球阀1之间不是刚性连接，而是通过阻尼弹簧4使活塞与球阀接触 球阀（活塞两端的液压力平衡）。由于活塞的阻尼作用，可使始终与活塞相连接的球阀运动平稳。 （Pa） （5－23） 式中，A为球阀座孔面积（m2）；K1、K2分别为主弹簧2和阻尼弹簧4的刚度（N/m）；x10、x20分别为主弹簧2和阻尼弹簧4的预压缩量（m）；x为球阀开口量（m）。由式（5－23）可知，由于增加了阻尼弹簧，相当于主弹簧的刚度增大了K2、预压缩量减小了K2x20/K1，有利于提高阀的静特性。 2、先导型溢流阀 由主阀和先导阀两部分组成。先导阀类似于直动型溢流阀，但一般多为锥阀（或球阀）形阀座式结构。

     主阀可分为一节同心结构、二节同心结构和三节同心结构。 图一、先导型溢流阀 图1为先导型溢流阀。由于主阀芯6与阀盖3、阀体4与主阀座7等三处有同心配合要求，故属于三节同心结构。压力油自阀体4中部的进油口P进入，并通过主阀芯6上的阻尼孔5进入主阀芯上腔，在油阀盖3上的通道a和锥阀座2上的小孔作用与锥阀1上。当进油口的压力p1小于先导阀调压弹簧9的调定值时，先导阀关闭，而且由于主阀芯上、下两侧有效面积比（A2/A1）为1.03～1.05，上侧稍大，作用与主阀芯上的压力差和主阀弹簧力均使主阀口闭紧，不溢流。当进油压力超过先导阀的调定压力时，截止阀先导阀被打开，造成资金油口P井主阀芯阻尼孔5、先导阀口、主阀芯中心孔至阀体4下部出油口（溢流口）O的流动。阻尼孔处的流动损失使主阀芯上、下腔中的油液产生一个随先导阀流量增加而增加的压力差，当它在主阀芯上、下作用面上产生的总压力差足以克服主阀弹簧力、主阀自重G和摩擦力Ff时，主阀芯开启。此时进油口P与出油口（溢流口）O直接相通，造成溢流以保持系统压力。 图2、二节同心先导型溢流阀的结构图 图2为二节同心先导型溢流阀的结构图，其主阀芯为带有圆柱面的锥阀。

        为使主阀关闭时有良好的密封性，要求主阀芯1的圆柱导向面和圆锥面与阀套配合良好，两处的同心度要求较高，故称二节同心。主阀芯上没有阻尼孔，而将三个阻尼孔2、3、4分别设在阀体10和先导阀体6上。其工作原理与三节同心先导型溢流阀相同，只不过油液从主阀下腔到主阀上腔，需经过三个阻尼孔。阻尼孔2和4只主阀下腔与先导阀前腔产生压力差，在通过阻尼孔3作用于主阀上腔，从而控制主阀芯开启。止回阀阻尼孔3还用以提高主阀芯的稳定性。溢流阀进出口压力为 （Pa） （5－24） 式中，Ac为先导阀座孔的面积（m2）；Ky、Kx分别为主阀和先导阀弹簧的刚度（N/m）；y0、x0分别为主阀和先导阀的预压缩量（m）；y、x分别为主阀和先导阀阀口的开度（m）；Ff为主阀与阀体间的摩擦力（N）；G为主阀芯自重（N）。

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译文：
            The use of pressure relief valve Overflow effects of constant pressure: the quantitative pump throttle adjustment system, quantitative pump to provide the constant flow. When the system pressure increases, will reduce traffic demand. At this point relief valve to open, so that excess flow back to the tank overflow to ensure the relief valve inlet pressure, pump outlet pressure is constant (often with the pressure fluctuations valve port open). Security role: the system workFilters properly, the valve closed. Only the load exceeds the limit (the system pressure exceeds the set pressure), the open overflow, overload protection, the system will not increase the pressure (usually to the tune set pressure relief valve system, the maximum working pressure higher than 10% to 20% ). For unloading valve For remote pressure regulator For high-voltage multi-level control valve For sequence valve Used to generate back pressure (string in the return oil on the road). 1, direct action type relief valve 1), cone-style direct action type relief valve Cone-valve direct-acting type relief valve Icon for the cone-valve direct-acting type relief valves. Cone valve 2 with bias set a left boosting suppress spring 5, the right end of a cone valve damping piston 3 (the one hand, the damping piston valve open or closed cone damping effect from the time, work to improve the stability of cone valve; other On the one hand to ensure the cone valve is opened, will not tilt). The pressure of imported oil (pressure P) can thus piston into the piston radial clearance at the bottom, forming a left hydraulic pressure F = P · A (A is the bottom area of the piston). When the role of fluid pressure in the bottom of the spring force greater than F, the cone valve port opens, the oil from the cone valve port via the return flow back to tank overflow. As long as the valve port to open, there is oil flowing through the relief valve, pressure relief valve entrance remained constant. By adjusting the rod 4 to change the pressure regulator spring preload 5 Ft, you can adjust the overflow pressure. Cone valve is opened, (5-21) The formula, K, X0, respectively spring stiffness and pre-compression (m); G for the spool weight (placement, consider the weight spool vertical, horizontal placement, regardless of weight) (N); Ff for the spool and valve Suite friction (the direction of movement in the opposite direction with the spool) (N); F5 force for the steady-state solution, because Forged Steel Valves the damping piston and the tapered valve junction for the cone, and symmetric with cone valve, so valve is opened in the cone into the oil flow and the oil flow, static hydraulic power balance each other, so F5 = 0; Fj for the jet power, in the end of the drift cone valve disk to open a circular groove to change the cone valve flow out of the mouth of the direction of flow to produce a spring force in the opposite direction of the jet power, when the flow through the relief valve to increase, although because the cone valve port to increase with increasing the spring force, but with the spring force in the opposite direction of the jet power and increase the results offset the spring force of the increment, that is. Taking into account F5 = 0 and Fj = Kx, then type (5-21) into (5-22) From (5-22) indicate that a valve inlet pressure P from flow changes, that is not valve opening P x Size. Charged with little change in pressure P, constant pressure and high accuracy. 2), ball-style direct action type relief valve Ball-style direct action type relief valve Icon for the ball-style direct action type relief valve. It also has a damping piston 3, but with different structures of cone valve, piston and valve 1 is not a rigid connection between, but through the damping piston and the valve spring 4 to contact (at both endsReducing Valves of the hydraulic piston pressure balance). As the piston of the damping effect, can always be connected with the valve piston movement smooth. (Pa) (5-23) The formula, A hole for the valve seat area (m2); K1, K2 are the main springs 2 and 4 the damping spring stiffness (N / m); x10, x20 are the main damping springs 2 and 4 of the pre-compression spring (m); x ball valve opening for the volume (m). From (5-23) can see, the addition of the damping spring, the equivalent stiffness of the main spring increases the K2, pre-compression reduces K2x20/K1, help to improve the static characteristics of valve. 2, pilot relief valve From the main valve and pilot valve composed of two parts. Pilot valve similar to the direct action type relief valve, but generally more for the cone valve (or ball) shaped seat structure. The main valve can be divided into a concentric structure, two concentric structures and three concentric structure. Figure 1, pilot relief valve Figure 1 is a pilot-type relief valve. As the main spool valve cover 6 and 3, valve 4 and the main valve seat 7, such as 3 are concentric with the requirements, it is three concentric structure. Pressure oil from the valve 4, the central inlet P to enter, and through the main spool orifice 5 of 6 on the upper chamber into the main spool in the valve cover and 3 on the channel a small hole on the cone seat 2 1 on the role and cone valves. When the inlet pressure p1 is less than the pilot pressure regulator valve spring 9 having a set value, the pilot valve closed, and because the main spool of upper and lower sides of the effective area ratio (A2/A1) was 1.03 ~ 1.05, on the side slightly larger, the main role of pressure difference on the spool and the valve spring force so that the main valve port are compressing, do not overflow. When the pilot valve into the oil pressure exceeds the adjusted set pressure, the pilot valve is opened, causing the oil port capital P well orifice 5 of the main spool, the pilot valve port, the main valve spool center hole to the lower part of the oil port 4 (overflow stream mouth) O flow. Loss of damping the flow of holes to the main API Cast Steel Valves spool, the lower chamber of the oil to produce a pilot valve flow increases with the increase in pressure difference, when it is in the main spool, the lower the role of surface generated a total pressure difference sufficient to overcome main valve spring force, the main valve weight and friction Ff G, the main valve to open. At this point the inlet port P and the oil (weir) O directly connected, causing the overflow to keep the system pressure. Figure 2, two concentric type pilot relief valve structure diagram Figure 2 shows two concentric type pilot relief valve chart as its main spool valve with a cylindrical surface of the cone. To enable the main valve off a good seal, asked a cylindrical main valve guide and a cone surface and the valve cover with a good, two of concentricity higher, it said two concentric. There is no main spool orifice, while the three were located in the 2,3,4-orifice valve 10 and pilot valve 6 on. It works with three concentric type pilot relief valve the same, just under the oil from the main valve to the main valve chamber cavity, and subject to three orifice. Orifice 2 and 4 under the main valve and pilot valve chamber before the chamber pressure difference generated in the orifice 3 by acting on Water power control valves the main valve chamber to control the main valve to open. Orifice 3 is also used to improve the stability of the main spool. Export pressure relief valve (Pa) (5-24) The formula, Ac is the area of the pilot valve seat hole (m2); Ky, Kx were the main valve and pilot valve spring stiffness (N / m); y0, x0 the main valve and pilot valves were pre-compression volume (m ); y, x, respectively the main valve and pilot valve port's opening (m); Ff the main valve and the body of friction (N); G main spool weight (N).

原文来源：http://www.1gemofa.com/

2010-08-31 08:54

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