Motor vehicles – Steering gear – With fluid power assist
Reexamination Certificate
1999-10-06
2001-12-18
Boehler, Anne Marie (Department: 3618)
Motor vehicles
Steering gear
With fluid power assist
C384S016000, C277S585000
Reexamination Certificate
active
06330929
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a rack and pinion steering gear assembly and, in particular, is directed to a bushing for a fluid power assisted rack and pinion steering gear assembly.
2. Description of the Prior Art
A typical fluid power assisted rack and pinion steering gear assembly for a vehicle includes a rack which extends axially through a chamber inside a hydraulic cylinder. The ends of the rack project from the ends of the hydraulic cylinder and are connected with steering linkage which connects to steerable vehicle wheels.
A piston is fixed to the rack within the chamber. Rotation of the vehicle steering wheel actuates a hydraulic valve and causes hydraulic fluid under pressure to act against the piston. The force exerted by the hydraulic fluid moves the piston within the chamber, causing the rack to move axially. The axial movement of the rack moves the steering linkage which, in turn, causes the steerable wheels to turn.
To prevent hydraulic fluid from flowing out of the chamber, it is necessary to seal the ends of the chamber through which the rack projects. It is also desirable to support the rack at least at one end of the chamber for axial movement within the chamber. Finally, it is common to enclose the ends of the chamber with bellows attached to the hydraulic cylinder to prevent the ingress of moisture, dirt, or other contaminant.
SUMMARY OF THE INVENTION
The present invention is a fluid power assisted rack and pinion steering apparatus for a vehicle, comprising a rack connectable with steerable wheels of the vehicle. The rack is movable in opposite directions to turn the steerable wheels in opposite directions. A housing partially encloses the rack and defines a fluid chamber. The housing has an inner surface. A bushing encircles the rack and supports the rack for sliding movement relative to the housing. The bushing has a recess on its outer periphery. A portion of the housing is deformed radially inward into the recess to secure the bushing to the housing. An annular first seal member encircles the rack and extends between the rack and the bushing. An annular second seal member encircles the bushing and extends between the bushing and the inner surface of the housing. A bellows member encircles the rack and has an end portion secured to the bushing.
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Feindel Robert E.
Gierc Daniel B.
Pietraszewski John A.
Boehler Anne Marie
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Inc.
Winner Tony
LandOfFree
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