Land vehicles – Wheeled – Running gear
Reexamination Certificate
2001-07-18
2003-05-27
Dickson, Paul N (Department: 3616)
Land vehicles
Wheeled
Running gear
C180S427000
Reexamination Certificate
active
06568698
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a rack-pinion type steering apparatus to be used for the wheels of motor vehicles or the like.
FIG. 7
is a front view, with portions broken away, of a rack-pinion type power steering apparatus of prior art, in which an auxiliary steering force is obtained by oil pressure. This steering apparatus comprises a steering shaft
92
connected to a steering wheel (not shown), a pinion
93
connected to the steering shaft
92
, a rack
94
meshed with this pinion
93
, a cylindrical metallic housing
95
in which the rack
94
is inserted, and a valve device
98
for supplying oil pressure, according to the steering force and the steering direction, to oil chambers
95
a
,
95
b
inside of the housing
95
. Through ball joints
96
, tie rods
97
are connected to the both ends of the rack
94
which project from the both ends of the housing
95
. Wheels are connected to the tie rods
97
through knuckle arms (not shown) or the like. With the arrangement above-mentioned, when the pinion
93
is rotated by a steering operation, the rack
94
is axially moved to change the steering angle.
A ring-like end cap
101
is mounted at one end of the housing
95
, and the rack
94
is slidably inserted in this end cap
101
. This end cap
101
is inserted in the inner peripheral surface of the end portion of the housing
95
. A cir-clip
102
wound on the outer periphery of the end cap
101
, restrains the end cap
101
from being moved axially of the housing
95
(See FIG.
8
). More specifically, annular grooves
103
,
104
are oppositely formed respectively in the inner periphery of one end of the housing
95
and the outer periphery of the end cap
101
, each annular groove
103
,
104
having a depth substantially equal to a half of the diameter of the cir-clip
102
(See FIG.
9
). The cir-clip
102
is inserted into the annular space defined by the annular grooves
103
,
104
, thus causing the end cap
101
to be engaged with the housing
95
.
The cir-clip
102
is made of a metallic wire and has, as shown in
FIG. 10
illustrating its free state before mounted, a linear winding portion
102
a
to be wound along the annular grooves
103
,
104
, and a hook portion
102
b
bent at one end of the winding portion
102
a
at a right angle thereto. The hook portion
102
b
is passed through an insertion opening
105
formed in the peripheral surface of the housing
95
and is hooked at an engagement groove
101
b
of the end cap
101
(See FIG.
11
). At this state, the end cap
101
is rotated with a tool such that while being wound in the annular groove
104
of the end cap
101
, the winding portion
102
a
of the cir-clip
102
is successively introduced inside of the housing
95
and is mounted in the space defined by the annular grooves
103
,
104
. At this time, the end cap
101
is rotated substantially by one and a half revolutions such that the hook portion
102
b
of the cir-clip
102
is located substantially at the opposite side of the insertion opening
105
with respect to the axis of the end cap
101
(See FIG.
8
).
In the steering apparatus above-mentioned, the ball joint
96
strikes the end cap
101
to regulate the maximum steering angle position in one direction (rightward moving stroke of the rack
94
in FIG.
7
). However, when the ball joint
96
strikes the end cap
101
with an excessive steering force applied to the rack
94
, a relative twist occurs between the ball joint
96
and the rack
94
. So, the end cap
101
may be slightly rotated together with the cir-clip
102
. When the end cap
101
is repeatedly rotated, there are instances where the tip of the cir-clip
102
is moved up to the insertion opening
105
of the housing
95
. This involves the likelihood that the tip of the cir-clip
102
springs out of the insertion opening
105
due to its spring back (See FIG.
12
), that the subsequent portion is consecutively gradually springs out of the housing
95
(See FIG.
13
), and that it becomes finally impossible to prevent the end cap
101
from being axially freely moved.
In this connection, provision is made as shown in
FIGS. 14 and 15
. That is, the other end of the cir-clip
102
is bent arcuately or linearly to form a bent portion
102
e
, and this bent portion
102
e
is resiliently mounted in the space defined by the annular groove
103
of the end cap
101
and the annular groove
104
of the housing
95
, thus restraining the cir-clip
102
from being rotated.
However, the former arcuately bent portion
102
e
easily follows the annular grooves
103
,
104
. Accordingly, the bent portion
102
e
cannot strongly resiliently be mounted in the space between the annular grooves
103
,
104
. This introduces the problem that the end cap
101
is not effectively prevented from being rotated. Further, when the bent portion
102
e
is moved to the insertion opening
105
of the housing
95
in association with the rotation of the end cap
101
, there are instances where the bent portion
102
e
runs onto the opening edge of the insertion opening
105
of the end cap
101
and springs out of the insertion opening
105
. Accordingly, the cir-clip
102
cannot securely be prevented from springing out of the housing
95
. The latter linearly bent portion
102
e
can strongly resiliently be mounted in the space between the annular grooves
103
,
104
, thus effectively preventing the end cap
101
from being rotated. However, stress concentration occurs at a bending starting point X. Therefore, the bending starting point X is disadvantageously readily broken and therefore poor in durability.
OBJECT OF THE INVENTION
It is an object of the present invention to provide a rack-pinion type steering apparatus capable of securely preventing, for a long period of time, the cir-clip from springing out of the housing.
SUMMARY OF THE INVENTION
A rack-pinion type steering apparatus according to the present invention comprises: a pinion connected to a steering shaft; a rack meshed with the pinion; a cylindrical housing in which the rack is inserted; an end cap inserted into one end of the housing with the rack inserted in the housing; and a cir-clip interposed between an annular groove formed in the outer periphery of the end cap and an annular groove which is opposite to the first-mentioned annular groove and which is formed in the housing, the cir-clip being arranged to prevent the end cap from being moved axially of the housing, the cir-clip being provided at an end thereof with (i) an inwardly bent curved portion and (ii) a linear portion linearly extending inwardly from the tip of the curved portion and having a tip which always comes in contact with the bottom of the annular groove in the end cap.
According to the rack-pinion type steering apparatus having the arrangement above-mentioned, when the end cap is rotated to cause the curved portion and the linear portion to be moved to the insertion opening of the housing, the curved portion and the linear portion are restored substantially to the original shapes, and the curved portion and its vicinities project from the insertion opening. At this state, the tip of the linear portion is held as coming in contact with the bottom of the annular groove of the end cap. Accordingly, the tip side of the linear portion or the curved portion can selectively be engaged with the opening edge of the insertion opening according to the rotational direction of the end cap. This securely prevents the end cap from being rotated. Further, the curved portion prevents stress concentration from occurring at one end of the cir-clip. Thus, there is no danger of the cir-clip from being broken. It is therefore possible to securely prevent, for a long period of time, the cir-clip from springing out from the insertion opening.
In the rack-pinion type steering apparatus of the present invention, the curvature radius of the curved portion of the cir-clip in a free state (before the cir-clip is mounted in the space between the annular grooves), is preferably smaller than the curvatu
Dickson Paul N
Dunn David R.
Koyo Seiko Co. Ltd.
Smith , Gambrell & Russell, LLP
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