Seal for a joint or juncture – Seal between relatively movable parts – Diverse and distinct dynamic seals
Reexamination Certificate
1999-04-06
2001-01-16
Melius, Terry Lee (Department: 3628)
Seal for a joint or juncture
Seal between relatively movable parts
Diverse and distinct dynamic seals
C277S402000, C277S549000, C277S560000
Reexamination Certificate
active
06173961
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an improved seal assembly which is used in a power steering system having a motor with an axially reciprocatable shaft.
A known power steering system has a hydraulic motor which is connected with steerable vehicle wheels. The hydraulic motor is operable to turn the steerable vehicle wheels. The hydraulic motor of the known power steering system includes a piston and a shaft which is connected with the piston and the steerable vehicle wheels. When the motor is operated to turn the steerable vehicle wheels, the shaft is reciprocated relative to a motor housing.
The known power steering motor includes a seal assembly which is disposed between the motor housing and the reciprocatable shaft. The seal assembly is connected with the housing. The seal assembly has a flexible lip which engages a cylindrical outer side surface of the reciprocatable shaft. After the power steering motor has been used for an extended period of time, the seal assembly may wear and develop a leak. It is desirable to maximize the operating life of a seal assembly before it begins to leak.
SUMMARY OF THE INVENTION
The present invention relates to a new and improved seal assembly for use in a power steering system having a motor with an axially reciprocatable shaft. The seal assembly has an inner side which is exposed to hydraulic fluid pressure during operation of the motor. The seal assembly has a flexible lip with a circular line of minimum diameter. An annular coil spring is disposed in engagement with a side of a flexible lip opposite from the line of minimum diameter.
The coil spring has a central axis which extends around a portion of the flexible lip. The central axis of the coil spring is offset from a plane containing the line of minimum diameter of the flexible lip in the direction toward the inner side of the seal assembly prior to installation of the seal assembly in the power steering system. It has been found that this construction increases the operating life of the seal assembly. The circular central axis of the coil spring may be advantageously offset from the plane containing the line of minimum diameter of the flexible lip in a direction toward the inner side of the seal assembly by a distance of between 0.15 and 0.75 millimeters prior to installation of the seal assembly in the power steering system.
REFERENCES:
patent: 3044786 (1962-07-01), Chillson
patent: 3685838 (1972-08-01), Malmstrom
patent: 4195854 (1980-04-01), Bertin
patent: 4351228 (1982-09-01), Schultz et al.
patent: 4410190 (1983-10-01), Potter
patent: 5181581 (1993-01-01), Engler
patent: 5709283 (1998-01-01), Nief
Melius Terry Lee
Miller William L.
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Inc.
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