Seal for a joint or juncture – Seal between relatively movable parts – Diverse and distinct dynamic seals
Reexamination Certificate
1999-05-27
2001-01-16
Dayoan, B. (Department: 3629)
Seal for a joint or juncture
Seal between relatively movable parts
Diverse and distinct dynamic seals
C277S476000, C277S437000
Reexamination Certificate
active
06173960
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a seal apparatus for sealing against a rod in a cylinder assembly such as a hydraulic cylinder for adjustment of a vehicle height, a hydraulic shock-absorber, etc.
In the above-mentioned cylinder assembly, a rod extends from an inside to an outside of a cylinder, and is slidably supported by a rod guide provided in the cylinder. For sealing a gap between the rod and the rod guide, in many cases, a double seal apparatus and an oil seal are arranged in the direction of the axis of the rod. The double seal apparatus comprises a rod seal which engages the rod, and a back-up ring which is provided radially outward of the rod seal to bias the rod seal toward the rod. A fluid which has leaked from an area between the rod and the rod seal is completely prevented from leaking to the outside, by means of the oil seal.
In the double seal apparatus, when axial compression of the back-up ring occurs due to the effect of the pressure of the fluid, the back-up ring radially expands and presses the rod seal against the rod. In order to prevent the application of an excessive force to the rod seal, a short partition wall is provided between the rod seal and the back-up ring. However, in the double seal apparatus in which the above-mentioned partition wall is provided, when the rod seal receives an axial-force due to the effect of the pressure of the fluid, the rod seal applies a force to the rod in an undesirable manner, which is caused by a dimensional error in production and thermal deformation of the partition wall and the rod seal.
SUMMARY OF THE INVENTION
In view of the above, the present invention has been made. It is an object of the present invention to provide a rod seal apparatus for a cylinder assembly, which is capable of always achieving an ideal contact surface pressure distribution with respect to a surface of contact between a rod seal and a rod, without being affected by a dimensional error and a difference in thermal expansion. In the rod seal apparatus of the present invention, not only can stable sealing performance be ensured, but also the wear life of the rod seal can be increased.
According to the present invention, there is provided a rod seal apparatus for sealing a gap between a rod and a rod guide. The rod guide is adapted to guide a sliding motion of the rod and defines a low-pressure side and a high-pressure side. The rod seal apparatus is provided in the rod guide and comprises a double seal provided within an annular groove formed on the inner circumferential surface of the rod guide. The double seal includes a rod seal which makes sliding contact with the rod and a back-up ring which resiliently biases the rod seal toward the rod. The rod seal has a stepped portion formed on an outer circumferential surface thereof. The rod seal apparatus also comprises a partition wall which extends from a seal-bearing surface on the low-pressure side of the annular groove toward a seal-bearing surface on the high-pressure side of the annular groove and is received in the stepped portion of the rod seal so that the rod seal and the back-up ring are partially separated from each other by the partition wall. The partition wall has a first abutment surface and the stepped portion of the rod seal has a second abutment surface, and the first abutment surface and the second abutment surface axially face each other. At least one abutment surface selected from the first abutment surface and the second abutment surface includes an engaging protrusion for engagement with the first abutment surface or second abutment surface axially facing the engagement protrusion.
In the above-mentioned rod seal apparatus, when the rod seal has force applied from the high-pressure side, the rod seal may deform so that the engaging protrusion restricts radial movement of the rod seal.
The foregoing and other objects, features and advantages of the present invention will be apparent from the following detailed description and appended claims taken in connecting with the accompanying drawings.
REFERENCES:
patent: 2994571 (1961-08-01), Peras
patent: 3268235 (1966-08-01), Jacobellis et al.
patent: 4917390 (1990-04-01), Lee et al.
Inose Yasuo
Machida Hiromi
Cottingham John R.
Dayoan B.
Tokico Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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