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.

 

对该液压系统存在的故障，我们运用速度刚度理论来分析升降液压缸举升速度不稳定的原因：

 

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.举升液压回路构成。油泵溢流阀、换向阀、换向阀、单向节流阀(无节流)、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.对举升回路建立速度刚性分析式。流入液压缸的流量，即流经单向节流阀的流量式中为流过节流阀的流量;节流阀的节流口形状及液压油粘性等有关的系数;AT进为节流口流通面积(提升无节流);液压泵的出口压力;P1为液压缸进油腔的压力，为提升液压缸柱塞面积;由节流口形状所决定的指数，得调速回路的速度式可知，当节流阀口面积不变时，液压缸输出速度将随负载的变化而变化。而负载的变化对速度的影响程度用速度刚度T来表示:因随负载的增加，升降机执行元件液压缸的输出速度减小负数;为使进为正数，故式中加一负号。代入液压升降机，得进口节流调速回路的速度刚度进值越大，液压回路速度稳定性越好。

 

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.

 

根据分析，我们不难得出如下结论：

 

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

 

1.当负载不变时，节流阀口进越小，则系统速度刚度进越高;反之，若节流阀开口面积越大，则进越低。

 

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.当负载不变时，低速下的速度刚度好，当负载变化时，负载小时的速度刚度好。

 

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.提高供油压力加大液压缸作用面积，可提高速度刚度。

 

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

 

综上所述，很多设备故障的原因都与液压有关，引发液压升降机该故障的主要原因便是液压系统提升调速回路设计不合理，值得相关企业注意。

 

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.