原文：
              液控单向阀的应用及故障与排除，介绍了液控单向阀的工作原理、类别及应用注意事项，对正确使用液控单向阀避免事故的发生进行了举例说明。同时，也列出了液控单向阀常出现的故障、产生原因及排除方法。

        液控单向阀是一种反向开启可控的单向阀，这类阀在冶金设备中应用较为广泛，由于其结构与原理的特殊性，生产现场因液控单向阀使用不当导致的故障经常发生。

          1、液控单向阀结构与工作原理 液控单向阀结构如图1所示。当控制油口不通压力油时，油液只能从PA→PB；当控制油口通压力油时，正、反向的油液均可自由通过。针型阀当油液反向流动时，阀芯的受力平衡表达式为： pKAK-pAAK-FKM=pBA-pAA=Fs+Fs+W(1) 式中pK———控制油压力，单位为N； pA———反向出油腔油液压力，单位为N； pB———反向进油腔油液压力，单位为N； FKM———控制活塞摩擦阻力，单位为N； FM———锥阀芯总摩擦阻力，单位为N； Fs———弹簧作用力，单位为N； W———阀芯重量，单位为N； AK———控制活塞面积，单位为m2； A———阀座口面积，单位为m2。

          当略去控制活塞和锥阀芯的摩擦阻力时，则控制油压力为： pK=[(pB-pA)A+Fs+W]/AK+pA(2) 该值是保证油液反向流动的控制油压力。若阀口关闭，油液反向流动停止，则出油腔压力pA=0。根据控制活塞上腔的泄油方式不同分为内泄式和外泄式。。外泄式液控单向阀，这种外泄式液控单向阀反向出油腔压力pA只作用在控制活塞的上端，同时，反向出油腔压力油和控制压力油泄漏到控制活塞上下段之间的容腔内，可通过外泄口直接引到阀体外，以避免由于泄漏油的聚积影响控制活塞的向上运动，故称为外泄式液控单向阀。复式结构液控单向阀，单向阀芯内装有卸载小阀芯。控制活塞上行时先顶开小阀芯使主油路卸压，再顶开单向阀阀芯，其控制压力仅为工作压力的4.5%，没有卸载小阀芯的液控单向阀的控制压力为工作压力的40%～50%。

            2、液控单向阀的应用 液控单向阀因泄漏量少、闭锁性能好、工作可靠而广泛运用谝苯鹨貉瓜低持校缌短嗯诨刈貉棺爸谩⒌缏缂祷芈贰⒌缏侠撼敌乙貉够芈返龋刖砣』貉瓜低掣谴罅渴褂靡嚎氐ハ蚍В缤?所示为液控单向阀在某轧机活套液压回路的应用。 液控单向阀具体应用场合如下： (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，铜阀门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，隔膜阀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。

          3、液控单向阀使用注意事项 现场实践证明，液控单向阀在使用维修过程中容易出现问题，以下是注意事项。 (1)必须保证液控单向阀有足够的控制压力，绝对不允许控制压力失压。应注意控制压力是否满足反向开启的要求。如果液控单向阀的控制引自主系统时，则要分析主系统压力的变化对控制油路压力的影响，以免出现液控单向阀的误动作。 (2)根据液控单向阀在液压系统中的位置或反向出油腔后的液流阻力（背压）大小，合理选择液控单向阀的结构（简式或复式）及泄油方式（内泄或外泄）。对于内泄式液控单向阀来说，当反向油出口压力超过一定值时，液控部分将失去控制作用，故内泄式液控单向阀一般用于反向出油腔无背压或背压较小的场合；而外泄式液控单向阀可用于反向出油腔背压较高的场合，以降低最小的控制压力，节省控制功率。 当反向进油腔压力较高时，则用带卸荷阀芯的液控单向阀，此时控制油压力降臀吹募阜种恢良甘种弧Ｈ绻∮昧送庑故揭嚎氐ハ蚍Вψ⒁饨庑箍诘ザ澜又劣拖淙缤?所示。另外，液压缸无杆腔与有杆腔之比不能太大，否则会造成液控单向阀打不开。液压缸上下腔作用面积之比大于液控单向阀的控制腔和单向阀芯的上作用面积之比，若液压缸的上下腔作用面积比为4:1，而液控单向阀控制活塞的作用面积与单向阀芯上部作用面积之比一般为（2.6～3.5）:1，则液控单向阀将永远不能打开。这时，液压缸将如同一个增压器一样，液压缸下腔严重增压，其压力为相工作压力的数倍，以致造成事故。因此一般工业用液压缸有杆腔作用面积与无杆腔作用面积之比通常取3:7～9:10。 (3)用两个液控单向阀或一个双液控单向阀实现 液压缸锁紧的液压系统中，应注意选用Y型或H型中位机能的换向阀，以保证中位时液控单向阀控制口的压力能立即释放，单向阀立即关闭，锻钢阀门活塞停止。假如采用O型或M型机能，在换向阀换至中位时，由于液控单向阀的控制腔压力油被闭死，液控单向阀的控制油路仍存在压力，使液控单向阀仍处于开启状态。而不能使其立即关闭，活塞也就不能立即停止，产生窜动现象。直至由换向阀的内泄漏使控制腔泄压后，液控单向阀才能关闭，影响其锁紧精度。但选用H型中位机能应非常慎重，因为当液压泵大流量流经排油管时，若遇到排油管道细长或局部阻塞或其他原因而引起局部摩擦阻力（如装有低压滤油器或管接头多等），可能使控制活塞所受的控制压力较高，致使液控单向阀无法关闭而使液压缸发生误动作。Y型中位机能就不会形成这种结果。 (4)工作时的流量应与阀的额定流量相匹配。 (5)安装时，不要搞混主油口、控制油口和泄油口并认清主油口的正、反方向，以免影响液压系统的正常工作。 (6)带有卸荷阀芯的液控单向阀只适用于反向油流是一个封闭容腔的情况，如液压缸的一个腔或蓄能器等。这个封闭容腔的压力只需释放很少的一点流量，即可将压力卸掉。反向油流一般不与一个连续供油的液压源相通。这是因为卸荷阀芯打开时通流面积很小油速很高，压力损失很大，再加上这时液压源不断供油，将会导致反向压力降不下来，需要很大的液控压力才能使液控单向阀主阀芯打开。如果这时控制管道的油压较小，就会出现打不开液控单向阀的故障。 (7)如图8所示系统液控单向阀不能单独用于平衡回路，否则活塞下降时，由于运动部件的自重使活塞的下降速度超过了由进油量设定的速度，致使缸6上腔出现真空，液控单向阀

           4的控制油压过低，单向阀关闭，活塞运动停止，闸阀直至液压缸上腔压力重新建立起来后，单向阀又被打开，活塞又开始下降。如此重复即产生爬行或抖动现象，出现振动和噪声。在无杆腔油口与液控单向阀4之间串联一单向节流阀5，系统构成了回油节流调速回路。这样既不致因活塞的自重而下降过速，又保证了油路有足够的压力，使液控单向阀4保持开启状态，活塞平稳下降。换向阀3应采用H或Y型机能，若采用M型机能（或O型机能），则由于液控单向阀控制油不能得到及时卸压，将回路锁紧，使工作机构出现停位不准，产生窜动现象。

         5、结论 理解液控单向阀结构与工作原理、故障规律及维护知识，掌握正确的使用方法，对改善液压系统、减少事故产生、提高维护液压系统效率有重要意义。

“ Check valve in the practical application and troubleshooting ”是由中国闸阀网提供的阀门行业新闻，译文仅供参考。另外，中国闸阀网还提供相关产品搜索： 平板闸阀、 弹性座封闸阀【软密封】、 不锈钢闸阀、 美标凸耳闸阀、 更多闸阀产品等。

译文：
               Fluid control valves Troubleshooting of the application and introduced the check valve working principle, types and application notes on the proper use of the check valve to prevent the accident was an example. It also lists the check valve failure often occurs, causes, and troubleshooting. Check valve is a reverse one-way valve controlled to open such valve in metallurgical equipment is widely used, due to its structure and principle of specificity, the production site because of check valve caused by improper use failure often occurs. 1, check valve structure and working principle Check valve structure shown in Figure 1. When the control oil port unreasonable pressure on oil, the oil only from the PA → PB; when the control pressure oil through the oil port, the forward and backward in the oil may pass through freely. When the reverse flow of oil, the spool by the force equilibrium expression is: pKAK-pAAK-FKM = pBA-pAA = Fs + Fs + W (1) Type in the pK --- control oil pressure unit N; pA --- reverse the oil chamber oil pressure, in units of N; pB --- reverse oil into the oil chamber pressure, in units of N; FKM --- control piston friction, in units of N; FM --- the total friction cone valve, unit N; Fs --- spring force, in units of N; W --- spool weight, in units of N; AK --- control piston area, in units of m2; A --- seat port area, in units of m2. When the spent control valve piston and the friction cone, then the oil pressure control: pK = [(pB-pA) A + Fs + W] / AK + pA (2) This value is to ensure that reverse flow of oil to control oil pressure. If the valve port closed, reverse flow of oil to stop, then the oil cavity pressure pA = 0. According to the control piston cavity drain in different ways within the discharge type and leaked into style. . Leakage-type check valve, this type check valve leaked the oil cavity pressure pA reverse effect only in control of the upper piston, while the reverse oil and the oil pressure control chamber pressure to control the oil leak volume between the upper and lower section of the piston cavity, can directly lead to valve leakage outside the mouth in order to avoid leakage of oil accumulation affect the control piston upward movement, so called leak-type check valve. Duplex structure, check valve, one-way valve that has the uninstall small spool. Control of the piston top with a small first row to the main oil line pressure relief valve, check valve spool Zaiding open its control pressure is only 4.5% of working pressure, no uninstall small spool of the check valve control pressure for the working pressure of 40% to 50%. 2, check valve applications Check valve for leak less, good locking performance, reliable and extensive use of show-off low benzene Pipit raccoon melon hold school  fine linen short   ah jest mow  raccoon coffin Dad Man ⒌ braid  Ke   prayer Mi II ⒌ braid  Xia B raccoon dog enough to shake the enemy  Mi back caries    cut off the feet and Weight 』 raccoon melon low button  contingent loopholes thirsty coat extravagant Hao Di ハ Pi В  Bean? shows the check valve at a mill Looper Application of the hydraulic circuit. Check valve specific applications as follows: (1) keep up the pressure. Slide valve has a valve clearance leakage, only a short time packing. When packing requirements, may be oil on the road plus a check valve, the cone valve closed tight, making the long holding pressure oil line. (2) cylinder of "supporting." In the vertical cylinder, since the slide valve and pipe leaks, the piston and piston rod of gravity, may lead to piston and piston rod down. The check valve connected in the hydraulic cylinder cavity under the asphalt, you can prevent the hydraulic cylinder piston and slide activities such as part of the decline. (3) of hydraulic cylinder lock. When the valve is in place, the two check valve closure, can be tightly closed chamber of the oil hydraulic cylinder 2, when the piston can not move because of external force generated. (4) large flow of oil discharge. The effective two-chamber hydraulic cylinder working area varied widely. When the piston back, the right cylinder chamber row oil suddenly increased, then the use of a small flow of slide valve, throttling effect will have to restrict the speed of the piston back; if an additional check valve in the hydraulic cylinder piston back, the control pressure oil will be controlled check valve is opened, it can be smoothly discharged oil the right cavity. (5) for oil filled valve. Vertical hydraulic cylinder piston at high speed down the process, because the role of high-pressure oil and weight, CHECK VALVESresulting in decreased rapidly, resulting in air and vacuum suction, must add up oil installations. Check valve as the oil-filled valves used to complete the fill oil function. (6) to form valve. In the design of hydraulic circuit, sometimes one-way valve can be hydraulically controlled valve to use synthetic. For example: with two check valve and a check valve in parallel (one-way valve center), the equivalent of a valve in the for-three links to the circuit. Be noted that the pressure control oily I do not work, should it pass back to the tank, otherwise the control piston is difficult to reset, one-way valve can not close the reverse flow. 3, check valve Caution Field proven, check valve during BALL VALVESthe use of easy maintenance problems, the following is a note. (1) must ensure that check valve controls the pressure enough, absolutely not allowed to control the pressure loss of pressure. It should be noted whether the control pressure to meet the requirements of the reverse turn. If the check valve control lead autonomous system, will have to analyze the change of the main system pressure control circuit pressures to avoid controlled check valve malfunction. (2) The check valve in the hydraulic system of the position or reverse flow after the oil chamber resistance (back pressure) the size, reasonable choice of check valve structure (short form or duplex), and oil spills means (within the vent or leak). Within the vent for the type check valve, when the reverse oil outlet pressure exceeds a certain value, the hydraulic control section out of control effect, it is within the vent-type check valve typically used to reverse the oil chamber without back pressure or back pressure less occasions; the leakage-type check valve can be used to reverse the high back-pressure oil chamber occasions, to reduce the minimum control pressure, the power saving control. Back into the oil chamber when the pressure is high, the unloading with the spool with the check valve, control the oil pressure drop at this time hip   species  blowing raise Fu Hui-liang Gan  species  arc H Quan  ∮ Mei Jie Hao sent veranda so ハ Pi Di В  ψ ⒁ feudal  veranda hoop interrogate ザ another bad drag Chung Lan Bean? shown. In addition, no rod hydraulic cylinder rod chamber cavity and the ratio can not be too much, otherwise it will cause check valve not open. The role of the upper and lower chamber of hydraulic cylinder area ratio is greater than the control check valve chamber and a one-way valve of the role of area ratio, if the hydraulic cylinder of the role of the upper and lower cavity area ratio was 4:1, while the check valve The role of control piston area and the upper part of the role of one-way valve area ratio generally (2.6 ~ 3.5): 1, check valve will never be able to open. At this time, the hydraulic cylinder will be the same as a turbocharger, cylinder under the sac pressurization, the pressure several times working pressure for the phase, resulting in the accident. Therefore, the general industrial cavity effect hydraulic cylinder rod chamber size and role of non-rod area ratio of 3:7 ~ 9:10 is usually taken. (3) with two check valve or a doubleBUTTERFLY VALVES check valve to achieve Hydraulic cylinder locking system, should be paid to the choice Y-or H-function valve in place to ensure that the median check valve when the pressure control port can be released immediately, immediately turn off one-way valve, piston Stop. If the use of O-or M-type function, the valve change to the medium, because check valve controls the pressure oil is closed cavity die check valve to control oil line there is still pressure on the liquid control one-way valve is still open. And not to immediately shut down, the Pistons would be unable to stop, resulting in shifting of the phenomenon. Until the leakage from the valve to control the internal cavity pressure relief after the check valve to close, affecting the locking accuracy. However, the median H-function used to be very careful, because when the pump flows through the hoses and high flow, if the oil discharge pipe thin face obstruction or other reasons or in part, caused the local friction (such as with low-pressure oil filter or more pipe joints, etc.), may control the high pressure piston control suffered, causing check valve can not be closures prevented cylinder malfunction occurred. The median Y-type function would not create such a result. (4) work flow valve rated flow should be matched. (5) installation, do not confuse the main oil port, control port and the oil drain port and identify the main oil port of positive and negative direction, so as not to affect the normal operation of hydraulic system. (6) with the unloading spool check valve is only applicable to reverse the oil flow is a closed working chamber of the situation, such as a chamber of hydraulic cylinder or accumulator, etc.. The closed chamber and the pressure just a little bit free flow, the pressure GATE VALVEScan be relieved. Generally do not reverse oil flow of hydraulic oil with a continuous source connected. This is because the unloading valve opens the oil flow area of a small high-speed, pressure loss, with the massive time hydraulic oil supply source continued, would lead to reverse the pressure drop is not over, takes a lot of liquid control pressure to make a one-way hydraulic control valve to open Fazhu. If less then the hydraulic control channel, there will not open check valve failure. (7) as shown in Figure 8, the system check valve can not be used for the balance of loop, otherwise the piston down, because the dead weight of moving parts to decline faster than the piston into the oil by the specified speed, resulting in 6-cylinder on a vacuum chamber, check valve 4, the control oil pressure is too low, one-way valve closed, piston stop, until the hydraulic cylinder on the cavity pressure re-established, one-way valve has been opened, the Pistons began to decline. Repeat that produce creep or chattering, vibration and noise occur. Oil port in the absence of rod chamber and check valve 4, a one-way throttle valve in series between the 5, the system constitutes a return to the oil throttle speed control loop. This is neither caused by the dead weight of the piston down too fast, but also ensure there is enough pressure oil line to check valve 4,GLOBE VALVE left open, a steady decrease of the piston. Valve 3 should be H or Y-function, the use of a M-function (or the O-function), due to check valve controls the oil can not get timely relief, the circuit locking, so that institutions have stopped the work place allowed, resulting in shifting of the phenomenon. 5, Conclusion Understand the check valve structure and working principle, failure to maintain law and knowledge, to master the correct way to use on the improvement of hydraulic systems to reduce accidents, increase the maintenance of hydraulic system efficiency are significant.

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2010-09-02 08:34

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