Created on:2022-02-25 10:55

Analysis and method of jamming of electromagnetic directional valve

Analysis and method of jamming of electromagnetic directional valve

1. Introduction

The electromagnetic directional valve is widely used in the hydraulic system. In the working process, the solenoid directional valve sometimes has the phenomenon of valve core jamming. Through the analysis, the jamming of valve core is mostly caused by hydraulic oil dirt. The following focuses on the analysis of the reasons for the jamming of the solenoid directional valve spool when the new hydraulic system is just installed and debugged. Years of practice has shown that the electromagnetic directional valve with stuck valve core during installation and commissioning is often a small diameter (≠ 6 or less) plate electromagnetic directional valve, while the Superposition valve is more prone to stuck valve core. Before these valves are installed in the hydraulic system, their valve cores move freely. When they are connected and fixed with the valve plate or manifold block with screws, the valve cores are stuck. This phenomenon is analyzed as follows.

2. Causes of jamming of valve core of small diameter plate electromagnetic directional valve

Fig. 184 (a) is a schematic diagram of small diameter plate electromagnetic directional valve and valve plate (block) tightened together with screws. When the valve plate (block) is processed, its flatness can generally reach sufficient accuracy according to the design requirements. Therefore, when the valve core is stuck after being fastened with screws, the reasons are shown in Fig. 184 (b) and (c). That is, when the bottom surface of the electromagnetic directional valve is concave [see Fig. 184 (c)], the valve body of the small-diameter electromagnetic directional valve is relatively thin. When it is fastened with the valve plate (block) with screws, the valve body is deformed, resulting in the valve core stuck in the valve cavity.

184.185

3. Causes of jamming of valve core of superimposed electromagnetic directional valve

As shown in Figure 185, when there is superposition between the electromagnetic directional valve and the valve plate (block), the valve core of the electromagnetic directional valve is more likely to be stuck. This is because the machining accuracy of the bottom surface of the electromagnetic directional valve and the upper and lower connecting surfaces of the superimposed throttle valve may be low in the process of adding and adding, and the accumulated error increases when superimposed together. After being fastened with screws, the valve body of the electromagnetic directional valve is deformed and the valve core is stuck.

In many years of practice, it has been found that the valve core of small-diameter plate electromagnetic directional valve and valve plate (block) are stuck sometimes after being tightened with screws. When a superimposed throttle valve is sandwiched in the middle, the valve core of solenoid valve is stuck often. This is because the closed body of the superimposed throttle valve is mostly cast iron. During the processing of the upper and lower joint surfaces, the cast iron valve body has not reached enough failure time. After a certain time, the upper and lower joint surfaces of the machined superimposed valve are deformed, which greatly reduces its flatness.

4. Solutions

During the installation and commissioning of the hydraulic system, it is not difficult to solve the problem because the cause of the stuck valve core is found out. The problem can be solved by reprocessing the bottom surface of the electromagnetic directional valve or the upper and lower surfaces of the superimposed throttle valve once to make its flatness reach sufficient accuracy.

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