Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
1999-03-24
2001-03-20
Rivell, John (Department: 3753)
Fluid handling
Systems
Multi-way valve unit
C091S37500R, C091S37500R
Reexamination Certificate
active
06202694
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a hydraulic power steering gear and, in particular, relates to a detent mechanism for an integral hydraulic power steering gear for turning dirigible wheels of a vehicle to effect steering of the vehicle.
BACKGROUND OF THE INVENTION
Integral hydraulic power steering gears are known. “Integral” refers to a steering gear containing a manual steering mechanism, a hydraulic control valve assembly, and a hydraulic power cylinder integrated into a single unit.
The hydraulic power cylinder typically comprises a chamber divided into two chamber portions by a piston. The piston has a set of teeth which mesh with a sector gear fixed to an output shaft. The output shaft is connected via steering linkage to dirigible wheels of a vehicle to steer the vehicle when the output shaft is rotated.
The hydraulic control valve assembly controls the flow of pressurized hydraulic fluid between a hydraulic pump and one of the chamber portions to control the direction and amount of steering. The valve assembly typically comprises two relatively rotatable valve elements, one of which is connected to a rotatable input shaft coupled to the vehicle steering wheel. The other valve element is connected with a follow-up member, such as a ball screw drive, which rotates in response to movement of the piston. The ball screw drive provides a direct connection between the input shaft and the piston to allow for manual steering of the vehicle in the event of hydraulic fluid pressure loss.
It is desirable for such an integral hydraulic power steering gear to provide the driver of the vehicle with a physically perceptible indication of operation of the steering gear between a neutral steering condition, in which the vehicle is being driven in a straight line, and an actuated steering condition, in which the vehicle is being turned. It is known to use a detent mechanism to provide the aforementioned physically perceptible indication to the driver.
SUMMARY OF THE INVENTION
The present invention is a hydraulic power steering gear for a vehicle. The power steering gear is operable between a neutral condition and an actuated condition. The power steering gear comprises a first valve member having a radially extending first passage, and a second valve member partially encircling the first valve member. The second valve member has at least one cam surface facing radially inward. The first and second valve members are rotatable relative to one another to selectively port hydraulic fluid. A ring member is fixedly attached to the first valve member. The ring member has a radially extending first bore radially aligned with the first passage in the first valve member. At least one detent member acts between the first and second valve members. The at least one detent member has a curved outer surface and is disposed in the at least one cam surface in the second valve member in the neutral condition to provide a physically perceptible indication to a driver of the vehicle of operation between the neutral condition and the actuated condition. At least one spring biases the at least one detent member radially outward. The at least one spring is disposed in the first passage in the first valve member.
A torsion bar acts between the first and second valve members. The torsion bar is at least partially disposed in an axially extending channel through the first valve member. A tubular spacer is disposed in the channel through the first valve member. The tubular spacer encircles the torsion bar and is engaged by the at least one spring. At least one plunger member is disposed in the first bore in the ring member. The at least one plunger member is biased radially outward against the at least one detent member by the at least one spring.
REFERENCES:
patent: 4034825 (1977-07-01), Adams
patent: 4759420 (1988-07-01), Schipper, Jr. et al.
patent: 4872393 (1989-10-01), Rabe et al.
patent: 5233906 (1993-08-01), Bishop et al.
patent: 5368058 (1994-11-01), Gold et al.
patent: 5575193 (1996-11-01), Bareis et al.
patent: 5957027 (1999-09-01), Gilbert et al.
patent: 37 398 48 A1 (1988-06-01), None
patent: 43 15 895 A1 (1994-11-01), None
patent: 197 32 874 A1 (1998-04-01), None
patent: 0749889 A1 (1996-12-01), None
patent: 0585259B1 (1997-08-01), None
patent: WO98/52812 (1998-11-01), None
A copy of an European Search Report dated 29 Jun. 2000.
Gilbert Wendell Lee
McCallum Lisa
Rivell John
Schoenfeld Meredith H
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Inc.
LandOfFree
Detent mechanism for a hydraulic power steering gear does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Detent mechanism for a hydraulic power steering gear, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Detent mechanism for a hydraulic power steering gear will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2453488