Arrangement for sealing a rod
First Claim
1. In a hydraulic device comprising a wall separating a high pressure area from a low pressure area, an opening in said wall which has a cylindrical surface, an annular groove provided in said surface, an axially movable rod traversing said opening, said rod and the cylindrical surface of said opening defining an annular space, a sealing arrangement positioned in said annular space between said rod and said surface, said sealing arrangement comprising a sealing ring consisting of a tough-elastic plastic material including harder elastomeric materials and a stressing ring consisting of a softer elastomeric material, the two rings being acommodated jointly in said groove in such a manner that one end of their common contact face points towards the high pressure area, the stressing ring being retained in sealing relationship between the circumferential face of said groove and the outer face of the sealing ring at an initial radial stress resulting from a certain oversize, and the sealing ring being provided, on its inner surface facing the rod, with two axially offset annular sealing edges being in sealing contact with the rod, wherein the said sealing ring comprises at least one channel connecting the annular space between the sealing edges with its outer surface and each opening defined by the end of said channel in the outer surface is covered by the said stressing ring and located between the highpressure end and the center of the common contact face of the said sealing ring and the said stressing ring.
1 Assignment
0 Petitions
Accused Products
Abstract
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.
29 Citations
5 Claims
- 1. In a hydraulic device comprising a wall separating a high pressure area from a low pressure area, an opening in said wall which has a cylindrical surface, an annular groove provided in said surface, an axially movable rod traversing said opening, said rod and the cylindrical surface of said opening defining an annular space, a sealing arrangement positioned in said annular space between said rod and said surface, said sealing arrangement comprising a sealing ring consisting of a tough-elastic plastic material including harder elastomeric materials and a stressing ring consisting of a softer elastomeric material, the two rings being acommodated jointly in said groove in such a manner that one end of their common contact face points towards the high pressure area, the stressing ring being retained in sealing relationship between the circumferential face of said groove and the outer face of the sealing ring at an initial radial stress resulting from a certain oversize, and the sealing ring being provided, on its inner surface facing the rod, with two axially offset annular sealing edges being in sealing contact with the rod, wherein the said sealing ring comprises at least one channel connecting the annular space between the sealing edges with its outer surface and each opening defined by the end of said channel in the outer surface is covered by the said stressing ring and located between the highpressure end and the center of the common contact face of the said sealing ring and the said stressing ring.
Specification