When the hydraulic elevator is put into use, it can meet the basic functional requirements. From the point of view of on-site use, there are often phenomena such as cigarette bag sliding, difficult to detect the rising position, unable to find the middle position, impact noise when rising, oil leakage of hydraulic cylinder and so on. According to the field observation, the main reason is that the lifting speed of the lifting hydraulic cylinder is too fast, which increases the failure rate and seriously affects the production efficiency. Analysis on the causes of unstable lifting speed of lifting hydraulic cylinder there are many reasons for the unstable lifting speed of lifting hydraulic cylinder, including design, processing, manufacturing and use.

 

對該液壓系統(tǒng)存在的故障，我們運(yùn)用速度剛度理論來分析升降液壓缸舉升速度不穩(wěn)定的原因：

 

For the faults of the hydraulic system, we use the speed stiffness theory to analyze the reasons for the unstable lifting speed of the lifting hydraulic cylinder:

 

1.舉升液壓回路構(gòu)成。油泵溢流閥、換向閥、換向閥、單向節(jié)流閥(無節(jié)流)、提升油缸。

 

1. Composition of lifting hydraulic circuit. Oil pump overflow valve, reversing valve, reversing valve, one-way throttle valve (without throttling), lifting oil cylinder.

 

2.對舉升回路建立速度剛性分析式。流入液壓缸的流量，即流經(jīng)單向節(jié)流閥的流量式中為流過節(jié)流閥的流量;節(jié)流閥的節(jié)流口形狀及液壓油粘性等有關(guān)的系數(shù);AT進(jìn)為節(jié)流口流通面積(提升無節(jié)流);液壓泵的出口壓力;P1為液壓缸進(jìn)油腔的壓力，為提升液壓缸柱塞面積;由節(jié)流口形狀所決定的指數(shù)，得調(diào)速回路的速度式可知，當(dāng)節(jié)流閥口面積不變時(shí)，液壓缸輸出速度將隨負(fù)載的變化而變化。而負(fù)載的變化對速度的影響程度用速度剛度T來表示:因隨負(fù)載的增加，升降機(jī)執(zhí)行元件液壓缸的輸出速度減小負(fù)數(shù);為使進(jìn)為正數(shù)，故式中加一負(fù)號。代入液壓升降機(jī)，得進(jìn)口節(jié)流調(diào)速回路的速度剛度進(jìn)值越大，液壓回路速度穩(wěn)定性越好。

 

2. Establish speed rigidity analysis formula for lifting circuit. The flow into the hydraulic cylinder, that is, the flow through the one-way throttle valve. In the formula, it is the flow through the throttle valve; The shape of the throttle port of the throttle valve and the coefficient related to the viscosity of the hydraulic oil; At inlet is the flow area of throttle port (lifting without throttle); Outlet pressure of hydraulic pump; P1 is the pressure of the oil inlet chamber of the hydraulic cylinder and the plunger area of the lifting hydraulic cylinder; According to the index determined by the shape of the throttle port, the speed formula of the speed regulating circuit is obtained. It can be seen that when the area of the throttle port remains unchanged, the output speed of the hydraulic cylinder will change with the change of load. The influence of load change on speed is expressed by speed stiffness T: with the increase of load, the output speed of elevator actuator hydraulic cylinder decreases by a negative number; In order to make the forward number positive, a minus sign is added to the formula. By substituting the hydraulic elevator, it is obtained that the greater the speed stiffness of the imported throttle speed regulation circuit, the better the speed stability of the hydraulic circuit.

 

根據(jù)分析，我們不難得出如下結(jié)論：

 

According to the analysis, it is not difficult for us to draw the following conclusions:

 

1.當(dāng)負(fù)載不變時(shí)，節(jié)流閥口進(jìn)越小，則系統(tǒng)速度剛度進(jìn)越高;反之，若節(jié)流閥開口面積越大，則進(jìn)越低。

 

1. When the load remains unchanged, the smaller the throttle inlet, the higher the speed stiffness of the system; Conversely, the larger the opening area of the throttle valve, the lower the inlet.

 

2.當(dāng)負(fù)載不變時(shí)，低速下的速度剛度好，當(dāng)負(fù)載變化時(shí)，負(fù)載小時(shí)的速度剛度好。

 

2. When the load is constant, the speed stiffness is good at low speed. When the load changes, the speed stiffness is good when the load is small.

 

3.提高供油壓力加大液壓缸作用面積，可提高速度剛度。

 

3. Increasing the oil supply pressure and increasing the action area of the hydraulic cylinder can improve the speed stiffness.

 

綜上所述，很多設(shè)備故障的原因都與液壓有關(guān)，引發(fā)液壓升降機(jī)該故障的主要原因便是液壓系統(tǒng)提升調(diào)速回路設(shè)計(jì)不合理，值得相關(guān)企業(yè)注意。

 

To sum up, many equipment failures are related to hydraulic pressure. The main reason for the failure of hydraulic elevator is the unreasonable design of lifting speed regulation circuit of hydraulic system, which deserves the attention of relevant enterprises.