Vehicle steering apparatus

Details Vehicle steering apparatus Vehicle steering apparatus

1998-06-19

2001-01-23

Johnson, Brian L. (Department: 3611)

Motor vehicles

Steering gear

With fluid power assist

C180S417000, C180S434000

Reexamination Certificate

active

06176342

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a hydraulically-assisted rack and pinion steering gear, and particularly relates to a housing for the steering gear.
BACKGROUND OF THE INVENTION
A hydraulically-assisted rack and pinion steering gear includes a steering rack, a pinion gear in mesh with the rack, and a hydraulic fluid control valve. The rack is movable longitudinally, and is connected at its opposite ends to a vehicle steering linkage. When the rack moves, it actuates the steering linkage to effect steering movement of an associated pair of steerable vehicle wheels.
Such a steering gear includes a housing which contains the rack, the pinion gear, and the valve. The rack extends through a horizontal section of the housing. The valve is contained in a tower section of the housing which projects upward from the horizontal section.
The horizontal section of the housing includes a hydraulic fluid power cylinder. A piston in the power cylinder is fixed to the rack. The valve cooperates with the pinion gear to control the hydraulic fluid pressure in the power cylinder in response to steering input from an operator of the vehicle. This causes the piston, and hence the rack, to move in response to the steering input so that the vehicle wheels are steered accordingly.
An example of a prior art steering gear is shown partially in FIG.
1
. The steering gear
10
of
FIG. 1
has a horizontal housing section
12
in which a steering rack
14
is supported for movement back and forth along a longitudinal axis
15
. The horizontal housing section
12
is defined in part by a hydraulic fluid power cylinder
16
and in part by a mounting structure
18
. The rack
14
projects longitudinally outward from the horizontal housing section
12
in a direction extending from left to right, as viewed in FIG.
1
. An outer end portion (not shown) of the rack
14
is connectable with a vehicle steering linkage in a known manner.
A cylindrical body portion
20
of the mounting structure
18
is received over the power cylinder
16
in an interference fit with the power cylinder
16
. A radially-projecting racket portion
22
of the mounting structure
18
defines a bore
24
. The bore
24
receives a bushing which, in turn, receives a fastener structure that fastens the steering gear
10
to a load-bearing structural part of a vehicle.
Other parts of the steering gear
10
that are shown in
FIG. 1
include a seal carrier
30
and a lock ring
32
. The seal carrier
30
is an annular structure extending into the power cylinder
16
concentrically between the rack
14
and the power cylinder
16
. An inner end surface
34
of the seal carrier
30
defines an outer end of a variable volume hydraulic fluid chamber
36
. An annular hydraulic fluid seal
38
(shown schematically) is supported on the seal carrier
30
in dynamic sealing contact with the rack
14
. An O-ring seal
40
is supported by the seal carrier
30
in static sealing contact with the power cylinder
16
. The lock ring
32
is received concentrically over the rack
14
in screw-threaded engagement with the body portion
20
of the mounting structure
18
. The seals
38
and
40
are thus retained in their installed positions at the end of the power cylinder
16
y the seal carrier
30
, the lock ring
32
and the mounting structure
18
.
SUMMARY OF THE INVENTION
In accordance with the present invention, an apparatus comprises a hydraulic fluid power cylinder and a steering rack. The rack is fixed to a piston in the power cylinder, and extends outward through an open end of the power cylinder. An annular hydraulic fluid seal is received over the rack in dynamic sealing contact with the rack. The seal defines a fixed end of a variable volume hydraulic fluid chamber extending from the piston to the seal.
The apparatus further comprises a housing part which is mounted on the power cylinder. The housing part supports the seal at a location spaced outward from the open end of the power cylinder. In this arrangement, the housing part defines an end section of the fluid chamber extending outward from the open end of the power cylinder to the seal.


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