| 摘要 |
An arrangement for sealing that point at which the axially movable rod of a hydraulic device passes through its housing wall, comprises a sealing ring consisting of a tough-elastic plastic material or a harder elastomeric material and a stressing ring consisting of a softer elastomeric material, the two rings being accommodated jointly in a groove in the housing wall in such a manner that the sealing ring projecting from the groove is in contact with the axially moving rod, while the stressing ring seals the sealing ring against the circumferential face of the groove. The sealing ring is provided, on its inner surface facing the rod, with two axially offset annular sealing edges. The annular space between these two sealing edges is connected with the outer surface of the sealing ring by a channel. The channel opens at a point where it is covered by the stressing ring and which is located near the high-pressure end of the common contact face of the sealing ring and the stressing ring. The channel and the sealing stressing ring form together sort of a non-return valve which allows any pressure fluid that has entered the annular space to flow off the annular space, against the surface pressure exerted by the stressing ring on the opening of the channel, when the pressure that has built up in the annular space exceeds the surface pressure. In this manner, it is ensured that the pressure in the annular space can never reach a value that may cause the outer sealing edge to be lifted off and that may result in notable leakage. |
