Relief valves are a vital component in your home's plumbing system, but they can sometimes fail. Understanding the causes of common failures and learning troubleshooting steps are critical to ensuring the smooth operation of your piping system. In this article, PHP editor Baicao will delve into common failures of overflow valves and provide step-by-step guidance to help you troubleshoot the problem easily.
When the relief valve is in use, common faults include noise, vibration, radial clamping of the valve core, and pressure regulation failure.
(1) Noise and Vibration
The components that are prone to noise in hydraulic devices are generally considered to be pumps and valves. Among the valves, relief valves and electromagnetic reversing valves are the main ones. There are many factors that produce noise. There are two types of noise from the relief valve: flow velocity sound and mechanical sound. The flow velocity sound is mainly caused by oil vibration, cavitation and hydraulic impact. Mechanical sound is mainly caused by the impact and friction of parts in the valve.
(1) Noise caused by uneven pressure
The pilot part of the pilot-operated relief valve is a vibration-prone part. When overflow occurs under high pressure, the axial opening of the pilot valve is very small, only 0.003 to 0.006 cm. The flow area is very small and the flow velocity is very high, up to 200 meters/second, which can easily cause uneven pressure distribution, causing the radial force of the poppet valve to be unbalanced and causing vibration. In addition, the ovality produced during the processing of the poppet valve and poppet valve seat, dirt sticking to the pilot valve port, and deformation of the pressure regulating spring can also cause vibration of the poppet valve. Therefore, it is generally believed that the pilot valve is the source of noise.
Due to the existence of elastic elements (springs) and moving masses (poppet valves), a condition for oscillation is formed, and the front cavity of the pilot valve also acts as a resonance cavity, so the vibration of the poppet valve can easily cause the entire The resonance of the valve causes noise. When noise occurs, it is usually accompanied by violent pressure jumps.
(2) Noise generated by cavitation
When air is sucked into the oil due to various reasons, or when the oil pressure is lower than the atmospheric pressure, part of the air dissolved in the oil will precipitate to form bubbles. These The bubbles have a larger volume in the low-pressure area. When the oil flows to the high-pressure area, they are compressed and the volume suddenly becomes smaller or the bubbles disappear. On the contrary, if the volume is originally small in the high-pressure area, but when it flows to the low-pressure area, A sudden increase in volume, a phenomenon in which the volume of bubbles in oil changes rapidly. The sudden change in bubble volume will produce noise, and because this process occurs in an instant, it will cause local hydraulic shock and vibration. The pilot valve port and main valve port of the pilot relief valve have large changes in oil flow rate and pressure, and cavitation is prone to occur, resulting in noise and vibration.
(3) Noise generated by hydraulic shock
When the pilot relief valve is unloading, pressure shock noise will occur due to a sudden drop in pressure in the hydraulic circuit. The more high-pressure and large-capacity working conditions the greater the impact noise. This is caused by the hydraulic impact caused by the short unloading time of the relief valve. During unloading, the oil flow rate changes sharply, causing a sudden change in pressure, causing The impact of pressure waves. The pressure wave is a small shock wave and generates very little noise. However, when the oil is transmitted to the system, if it resonates with any mechanical part, it may increase vibration and noise. Therefore, when hydraulic impact noise occurs, it is usually accompanied by system vibration.
(4) Mechanical noise
The mechanical noise emitted by the pilot relief valve generally comes from the impact of parts and the friction of parts due to machining errors.
Among the noise emitted by the pilot relief valve, there is sometimes mechanical high-frequency vibration sound, which is generally called self-excited vibration sound. This is the sound caused by high-frequency vibration of the main valve and pilot valve. Its occurrence rate is related to factors such as the configuration of the oil return pipeline, flow rate, pressure, oil temperature (viscosity), etc. Generally speaking, when the pipeline diameter is small, the flow rate is small, the pressure is high, and the oil viscosity is low, the occurrence rate of self-excited vibration is high.
Measures to reduce or eliminate the noise and vibration of the pilot relief valve are generally to add a vibration damping component to the pilot valve part.
The vibration-absorbing sleeve is generally fixed in the front cavity of the pilot valve, that is, in the resonance cavity, and cannot move freely. Various damping holes are provided on the vibration-absorbing sleeve to increase damping and eliminate vibration. In addition, due to the addition of parts in the resonant cavity, the volume of the resonant cavity is reduced, and the stiffness of the oil increases under negative pressure. According to the principle that components with high stiffness are less likely to resonate, the possibility of resonance can be reduced.
Vibration-absorbing pads generally cooperate with the resonant cavity and can move freely. There is a throttling groove on the front and back of the vibration-absorbing pad, which can produce a damping effect when the oil flows to change the original flow situation. Due to the addition of the vibration-absorbing pad, a vibrating element is added, which disrupts the original resonance frequency. A vibration-absorbing pad is added to the resonant cavity, which also reduces the volume and increases the stiffness of the oil when it is under pressure to reduce the possibility of resonance.
There are air storage holes and throttling edges on the vibration-absorbing screw plug. Because there is air in the air storage holes, the air is compressed when it is under pressure. The compressed air has a vibration-absorbing effect, which is equivalent to a micro-vibration absorber. When the air in the small hole is compressed, the oil is filled in, and when it expands, the oil is forced out, thus adding an additional flow to change the original flow situation. Therefore, noise and vibration can also be reduced or eliminated.
In addition, if the relief valve itself is improperly assembled or used, it will also cause vibration and noise. For example, the three-section concentric relief valve has improper coordination of the three concentric sections during assembly, the flow rate is too large or too small during use, and the poppet valve is abnormally worn, etc. In this case, the adjustment should be carefully checked, or the parts should be replaced.
How to troubleshoot common faults of the relief valve
(2) Radial clamping of the valve core
Due to the influence of machining accuracy, the main valve core is radially clamped, causing the main valve to open and not pressurize or the main valve not to close. Relieve pressure, and cause radial clamping due to contamination.
(3) Pressure regulation failure
Pressure regulation failure may sometimes occur in the relief valve during use. There are two situations when the pilot relief valve fails to regulate pressure: one is that the pressure regulating handwheel cannot build up the pressure, or the pressure cannot reach the rated value; the other is that the pressure of the regulating handwheel does not decrease, or even continues to increase. When pressure regulation failure occurs, in addition to the radial clamping of the valve core due to various reasons, there are also the following reasons:
The first is that the damper of the main valve body (2) is clogged, and the oil pressure cannot be transmitted to the upper chamber and guide of the main valve. In the front cavity of the valve, the pilot valve loses its ability to regulate the pressure of the main valve. Since there is no oil pressure in the upper chamber of the main valve and the spring force is very small, the main valve becomes a direct-acting relief valve with a very small spring force. When the pressure in the oil inlet chamber is very low, the main valve opens the relief valve. flow, the system cannot build up pressure.
The reason why the pressure cannot reach the rated value is that the pressure regulating spring is deformed or incorrectly selected, the compression stroke of the pressure regulating spring is insufficient, the internal leakage of the valve is too large, or the poppet valve of the pilot valve part is excessively worn, etc.
The second is that the damper (3) is clogged and the oil pressure cannot be transmitted to the poppet valve, so the pilot valve loses its ability to regulate the pressure of the main valve. After the damper (small hole) is blocked, the poppet valve will not open to overflow oil under any pressure. There is always no oil flow in the valve. The pressures in the upper and lower chambers of the main valve are always equal. Since the annular pressure-bearing area at the upper end of the main valve core is larger than The lower end has an annular pressure-bearing area, so the main valve is always closed and will not overflow. The main valve pressure increases as the load increases. When the actuator stops working, the system pressure will increase indefinitely. In addition to these reasons, it is also necessary to check whether the external control port is blocked and whether the poppet valve is installed properly.
(4) Other faults
During assembly or use of the relief valve, due to damage to the O-ring seal, the combined seal ring, or the loosening of the mounting screws and pipe joints, undue leakage may occur.
If the poppet valve or main valve core is too worn, or the sealing surface is in poor contact, it will cause excessive internal leakage and even affect normal operation.
Common faults of electromagnetic relief valves include failure of the pilot solenoid valve, failure of pressure regulation of the main valve and impact noise during unloading, etc. The latter can be reduced or eliminated by adjusting the added buffer. If there is no buffer, a back pressure valve can be added to the main valve overflow port. (The pressure is generally adjusted to about 5kgf/cm2, that is, 0.5MPa).
Freezer is one of the commonly used appliances in the home, which can provide us with the convenience of preserving food ingredients and cold drinks. However, when the freezer is used for a long time, some failures sometimes occur, affecting normal use. This article will introduce some common freezer failures and provide corresponding troubleshooting methods to help you quickly solve the problem and restore the freezer to normal working condition.
If you find that the cooling effect of the freezer has deteriorated, it may be due to the following reasons:
The freezer door is not closed properly, causing air conditioning to leak out. There is accumulation of dust around the freezer, which affects the heat dissipation effect. The freezer thermostat is not set properly. The condenser fins are blocked by foreign objects.Solution: Please make sure the freezer door is closed tightly, clean the dust around the freezer regularly, adjust the thermostat to the appropriate temperature, and clean foreign objects on the condenser fins.
If there is a peculiar smell in the freezer, it may be caused by the following reasons:
The food is not packaged well and gives out a peculiar smell. There is mold or bacteria growing in the freezer. The freezer has not been cleaned for a long time.Solution: Clean the food residue in the freezer promptly, clean the freezer regularly, and use special deodorant to remove odors.
Freezer leaking may be caused by the following reasons:
The freezer drain hole is clogged. The freezer seal is aging. Freezer defrost system failure.Solution: Clean the drainage hole of the freezer, replace the aging sealing strip, repair or replace the defrost system, and keep the inside of the freezer dry.
If the freezer won’t start, you can troubleshoot as follows:
检查电源插头是否插紧。 检查电源线是否破损。 确认电源开关是否打开。 检查保险丝是否烧毁。解决方法：确保电源插头插紧，更换破损的电源线，打开电源开关，更换坏掉的保险丝。
冰柜在日常使用中，有时会遇到一些故障问题，但大部分故障都可以通过简单的排除方法解决。定期保养和清洁冰柜是避免故障的关键，另外，正确使用冰柜也能延长其使用寿命。希望以上介绍的冰柜常见故障排除方法能够帮助到您，让您的冰柜恢复正常工作，为家庭提供良好的冷藏和冷冻功能。
很多朋友刚摸车的时候儿，觉得车子是个很神秘的东东，生怕哪儿一个不小心，就给车弄坏了，挺金贵的东西。其实并没有那么夸张，今儿就跟大家说说这车子的常见故障。
1
刹车指示灯亮
刹车指示灯亮，在咱平时行驶过程中最有可能的就是刹车片过薄，或是刹车油油位低。这事儿马虎不得，是严重的安全隐患。您要是不幸中枪了一定先靠边停车，查看一下有没有刹车油渗漏的痕迹，要是有建议找拖车救援，如果没有也不要再把车开快，找附近的修理厂维修好再上路。
2
水温状态指示灯
这个灯是我最记忆犹新最痛恨的了，它一亮基本上就事儿大了，水温报警一定要靠边停下，如果再开可能把缸垫疵了。用怠速等一会看看水温有没有下去，如果不行就熄火把车晾一会儿再拧开水箱盖加水吧，记着是水箱盖不是副水箱，拧开的时候一定要垫毛巾谨防烫伤，这玩意儿有可能就是因为水箱盖老化导致的，修的时候别听黑修理厂忽悠，上来就告诉你水泵报销了。
3
反向盘突然变沉
有时候突然觉得方向沉了别着急往修理厂跑，您先下车看看是不是前面儿两轮有一个亏气了，找地方把气补满就可以啦。再要不行就看看助力油是不是出问题了，最后再往那贵的助力系统上想，其实老实说，我过手的这么多车助力系统出问题的还真没遇到过。
4
大灯不亮
这事儿其实说来容易很可能就是车子的保险烧了，找到您车子的保险位置，按照上面的标号找下大灯的，然后摘下来换掉即可，要么就是接触不良，灯泡坏的不多，更换起来成本也不算太高。
5
冒蓝烟
排气管冒蓝烟还伴有焦糊味道，而且噪音变大，车子开起来没劲儿多是由于发动机内部故障，烧机油。购买二手车的时候格外要注意这个，这玩意儿要是烧了机油虽然也是混合动力了，可用车太贵了，机油一桶也不便宜呢。
货车
1、bcm故障是车身控制器的故障。修复方法是将ADC输入口接到比较器的输入端，比较器电路的输出接到MCU的中断捕获IO口。如果检测到上升沿中断，则表明存在短路故障。
2、车身控制器，简称bcm，是指汽车工程中用来控制车身电气系统的电子控制单元(ECU)，是汽车的重要部件之一。
3、车身控制器常见的功能有控制电动车窗、电动后视镜、空调、大灯、转向灯、防盗锁止系统、中控锁、除霜装置等。车身控制器可以通过总线与其他车载ECU连接。
砂光机9大常见故障及解决办法分析
砂光机在运行过程中，经常会出现一些故障，但是这些应及时排除，但如果处理不当，可能会影响生产，增加成本。这就要求操作人员必须熟悉操作章程，熟练操作，及时排除。本文是对砂光机9大常见故障及解决办法的分析。
故障⒈砂带跑偏
一般由于调整不当引起，正常的砂带摆动应该是摆幅为15-20mm，摆频为15-20次/分，摆速适中且摆进摆出速度一致。如果处在非正常状态，时间一长，可能出现跑偏现象，尤其是摆进摆出速度不一致，更易引发异常停机现象;光电开关损坏、电磁阀损坏、摆动气缸缸损坏。吸尘不佳，粉尘浓度高都会影响光电管正常工作，也引起砂带跑偏;应及时更换损坏的配件，改善除尘效果。
故障⒉限位失灵
砂带两侧均有限位开关，当砂带摆动失灵，往一侧跑偏时，碰限位开关，砂带松开，主电机自动停止，可有效保护砂带。一旦限位失灵可引起砂带损坏，磨擦机架产生火星，甚至引起火灾。因此限位开关应经常检查动作是否可靠。
故障⒊砂带起皱
砂带一旦起皱就无法再使用，一般引起砂带起皱有三种可能：砂辊与张紧辊磨损造成，研磨想、修复辊;砂带受潮发软引发起皱，可采用烘干晒干等办法处理;砂光机长时间不使用砂辊表面生锈粗糙，砂带摆动困难引发起趋，此时应对辊筒除锈或用较细砂纸打磨。
故障⒋砂带断裂
砂带断裂主要由于砂带跑偏，或砂带磨钝没有及时更换，或砂削负荷过大，或砂削过程中遇硬物，或砂带本身质量问题引起。应尽量避免砂带断裂，否则可能引起火灾。当电流发生异常，应观察砂带是否已磨钝，如果是应及时更换。
故障5.进板跑偏
打滑、反弹、在砂光机的调整中要求把上输送辊反压弹簧调整到三分之二(剩三分之一)，上输送辊和下输送辊间隔应比通过的板坯厚度少1.5mm或1mm，否则会引起板坯跑偏或打滑。严重时引起反弹，这可能会伤及人身安全。
故障6.更换砂带后砂削板尺寸发生变化
砂光机的悬臂在锁紧块松开或锁紧时，位置波动较大，正常应在0.5mm以内。如果太大，当锁紧块锁紧悬臂时，锁紧力的大小差异会使悬臂的重复精度发生差别，引起砂光板尺寸波动，直接影响砂光机砂削精度。当发生悬臂误差太大时(超过0.5mm)应拧开锁紧块固定螺栓适当调整，同时在更换砂带时，锁紧块锁紧力度应一致。
故障7.空车时下输送辊断续转动或不转
工作时，一般不能观察上述情况，只有在空车时才能发现，原因是传递动力的蜗轮减速中蜗轮部分磨损或全部磨损。虽然不会对工作造成影响，但其他蜗轮会由于工作负荷加重，而缩短寿命，造成更大损失。因此，一旦发现这种情况，应立即更换。
故障8.主轴承座振动异常
正常情况下主轴承座振动很小，有经验的操作员一摸就能判断是否正常，在现场一般没有条件用仪器测量，但可以采用和其他轴承座对比来判断，也可以从砂光板表面优劣来判断。当发生轴承座振动异常时，可以认为有二种原因，一是轴承损坏，只要更换轴承即可，二是接触辊发生磨损，失园，原有动平衡破坏，造成振动异常，这种情况必须拆下砂辊进行维修。
故障9.主传动皮带打滑
在Q型与M型砂光机中，都采用了高速平皮带。这种传动形式从理论上讲比三角带传动效率高。但在实际使用中，会产生皮带跑偏或打滑现象，这主要是调整不当引起。应严格按照皮带延伸率1.5-2%的要求调整，并且皮带两侧松紧一致。当按要求调整完毕后，应进行试运转，特别是主电机电流突然升高时，观察皮带是否跑偏，如果跑偏，应进行二次调整。
1、喷孔堵塞，可用通针进行疏通，疏通后要经仔细地清洗。针阀体大平面与喷油嘴主体平面接触不良，或针阀圆柱面磨损较大。若针阀体大平面与喷油嘴主体平面接触不良，可用氧化铬涂在平板上进行“8”字形研磨；若针阀圆柱面磨损较大，应成对更换针阀偶件。
2、密封不良，针阀和针阀体密封不良，造成喷油嘴雾化不良或滴油。这种故障可用细的氧化铬或牙膏，涂在针阀端的密封带上，但千万不要涂到圆柱部分，再将针阀插入针阀体，边敲边转直到密合。研磨后必须将氧化铬或牙膏洗去。
3、有空气，在油路中有空气。只需将油路中的空气排除即可。
4、供油不畅，需对输油泵进行检修。如因输油管接头漏气，可设法接好，使其不漏。
5、弹力不足，活塞弹簧的弹力不足或弹簧折断。应更换弹簧。
6、活塞磨损，活塞磨损影响供油。则需对活塞进行更换。
1、故障一：插上电源插头，电源保险丝马上熔断。原因及检修：（1）电饭煲电源插座内进水或米汤，造成短路。这种情况可以将插座内吹干水分后继续使用;（2）电饭煲电源插座或插头由于长期使用，其表面碳化短路。这种情况可用细砂纸将其表面碳化层磨掉，并用酒精擦干净。
2、故障二：煮好饭后不能保温。原因及检修：此故障可能是保温开关的常闭触点表面脏污或烧蚀，使其触点接触电阻过大，造成触点闭合而电路不通，发热管不发热，电饭煲不能保温。此时可用细砂纸将触点表面清理干净后，镀上一层锡。若仍不保温可更换保温开关。
3、故障三：煮煳饭。原因及检修：此故障可能是保温开关的常闭触点烧结粘在一起，虽然饭已经煮好，限温器也跳下，但保温开关仍在继续给发热管通电，饭就煳了。此时可用小刀把触点分开，然后用细砂纸将触点表面清理干净。
4、故障四：煮夹生饭。原因及检修：此故障一般是限温器内的永久磁环磁力减弱造成的。此时可拆开电饭煲的限温器检查磁环是否断裂、吸力如何。若永久磁环断裂则必须更换相同型号的限温器;若吸力减小，可调节限温器上的调温螺钉，每次调节1/4圈，调节一次试煮饭一次。
5、故障五：不能煮饭。原因及检修：（1）源导线断路。用万用表的欧姆挡检查电源导线;（2）限流电阻熔断。此时可用万用表的欧姆挡检查该电阻。若该电阻熔断必须用同型号限流电阻代替，不能直接用导线代替;（3）发热管烧断。没有限流电阻的电饭煲长时间工作，烧断发热管。此时用万用表的欧姆挡检查发热管，若断路则必须连同发热盘一起更换。
丰田花冠启动性故障的原因为：汽车的发动机节气门装置被卡住所导致的情况。
解决方法为：如果是汽车的节气门装置故障的话，需要及时前往汽车的4S店或者是维修店对汽车的节气门装置进行检修即可解决汽车的启动性故障。
如果节气门不清洗，空气从节气门流过，自然会有很多灰尘和沙粒进入节气门，再加上曲轴箱带出来的机油蒸汽，从而形成黑色油灰沉积层，从而导致节气门运动不灵活。过度的清洗会导致节气门过早报废，一次次频繁清洗造成节气门的内腔的特殊涂层被逐渐清洗掉。
故障一：蒸汽挂烫机无蒸汽
1、电源掌控开关没开启——检验挂烫机是否接上电源，如没有请开启电源掌控开关。
2、水箱水量过少——关掉挂烫机再煮沸。
3、蒸汽管折死——保证挂烫机的蒸汽管是几乎找出的。
4、水箱中没有水——关掉挂烫机进行煮沸。
5、蒸汽指示灯未亮——待灯亮后，开启水泵掌控按钮，水泵工作灯亮后可以使用。
6、水泵工作指示灯未亮——按手柄上水泵掌控按钮，灯亮有蒸汽
7、踏板指示灯未亮——检验产品到底准确的接上电源，开启踏板电源掌控开关。
8、把手工作指示灯未亮——按蒸汽头掌控按钮，灯亮有蒸汽。
故障二：蒸汽挂烫机蒸汽量少
1、挂烫机没有定时清洗水箱里过滤器棉——最少每年也许总计运用100个小时要进行除垢。假如您运用的水是硬水，需要合理提高清洗频率。
2、水量过少——关掉挂烫机电源，向水箱煮沸。
3、水量太多——关掉挂烫机电源，把水箱中多余的水倒掉。
故障三：蒸汽挂烫机蒸汽头滴水
1、水管中存有液化水——请不想水平方向使用，横向高度拿住蒸汽管使蒸汽管中的水返回挂烫机中。
2、蒸汽头本身的问题，蒸汽头滴水，一般与蒸汽刷的设计有关，这时可以替换挂烫机。
故障四：蒸汽挂烫机预热时间过长
水箱中水量太多——拔除挂烫机电源，将水箱中多余的水倒掉。
挂烫机内有积垢——常常使用挂烫机，最少确保每年或者总计使用100个小时要进行除垢。如果是在硬质水的地区，则要更为频繁的清洗挂烫机。
故障五：蒸汽挂烫机缺水自动断电
在使用中当发热锅的温度抵达一定程度后，会自动断电，首先确认到底忘记煮沸或者是水用完了，再者就是确认下进水孔有没有阻塞，如果是这两种原因根据情况处理一下应当就没问题了。
按控制面板“开投影机”按键后，投影机不亮。 按键后需要等待几秒钟，查看投影机指示灯是否变绿，如果投影机点亮后投影幕蓝屏，没有信号输入，根据输出信号来源进行信号切换，如按电脑、笔记本、展台等按键。 为什么投影机被关闭后立即再按“投影开”键但不响应？ 由于投影机关闭后需要一段时间散热，此时投影机不能接受任何指令。
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