Sealing device in common hydraulic system

Sealing is the most important and effective means to solve the problem of hydraulic system leakage. If the hydraulic system is not well sealed, there may be unallowable leakage, and the leaked oil will pollute the environment; it may also cause air to enter the oil suction cavity, affecting the working performance of the hydraulic pump and the smoothness of the hydraulic actuator movement (crawling); When the leakage is serious, the volumetric efficiency of the system is too low, and even the working pressure cannot reach the required value. If the sealing is excessive, although leakage can be prevented, it will cause severe abrasion of the sealing part, shorten the service life of the seal, increase the frictional resistance in the hydraulic components, and reduce the mechanical efficiency of the system.

   According to its working principle, the seal can be divided into non-contact seal and contact seal. The former mainly refers to gap sealing, and the latter refers to seal sealing. The gap seal is sealed by the small gap between the mating surfaces of the relative moving parts. It is often used in the cylindrical mating pair of plungers, pistons or valves. The advantage of this kind of seal is that the friction is small, but the disadvantage is that it cannot be automatically compensated after wear. It is mainly used between cylindrical surfaces with a small diameter, such as between the plunger and the cylinder in a hydraulic pump, and between the spool of the spool valve and the valve hole.

   Commonly used seals in hydraulic systems include O-rings, Y-rings, V-rings, dust-proof rings, etc.