The commonly used self-sealing compression type hydraulic seals are mainly ○-shaped sealing rings, circular sealing rings and square sealing rings, etc. They have the advantages of simple structure, easy manufacture and low cost, so they are widely used in hydraulic transmission systems. Dynamic sealing elements and static sealing elements. They are installed in the sealing groove and usually produce 10-25% radial compression deformation, and produce a high initial contact stress on the sealing surface, thereby preventing the leakage of unpressurized liquid.
When the hydraulic cylinder is working, the pressure liquid squeezes the self-sealing compression type hydraulic seal to further deform it, and generates a large pressure of the pressure liquid on the sealing surface, strictly speaking, it should be the pressure. The increased and increased additional contact stress, together with the initial contact stress, prevents the leakage of the pressurized liquid. However, when the working pressure is greater than 10Mpa, in order to avoid leakage caused by a part of the synthetic rubber self-sealing compression type hydraulic seal being squeezed into the sealing gap and being cut off during the reciprocating motion of the hydraulic cylinder, the synthetic rubber self-sealing pressure A synthetic resin retaining ring, such as a nylon retaining ring, a polyoxymethylene retaining ring and a filled polytetrafluoroethylene retaining ring, is provided on the pressure side of the tight hydraulic seal.
Since the synthetic rubber self-sealing compression type hydraulic seal has a large compression deformation during operation, its static friction resistance is particularly large, usually more than twice its dynamic friction resistance. Such a large static frictional resistance is bound to cause undesirable phenomena such as low-pressure crawling and difficult operation in some low-pressure hydraulic transmission systems.
