Land vehicles – Wheeled – Running gear
Reexamination Certificate
2001-08-28
2003-07-22
Morris, Lesley D. (Department: 3619)
Land vehicles
Wheeled
Running gear
Reexamination Certificate
active
06595532
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a rack-pinion type steering apparatus to be used for a vehicle of an automobile or the like.
DESCRIPTION OF THE PRIOR ART
FIG. 3
is a section view of a main portion of a conventional rack-pinion type steering apparatus. As shown in
FIG. 3
, the conventional rack-pinion type steering apparatus has a pinion shaft
83
supported, rotatably with respect to a housing
80
, by bearings
81
,
82
and provided at the tip thereof with a pinion
83
a,
and a rack shaft
84
supported in a perpendicular direction to the pinion shaft
83
and having a rack
84
a
to be meshed with the pinion
83
a.
The pinion shaft
83
is connected to a steering wheel (not shown), and the rack shaft
84
is connected to steering wheels (not shown). A back side of the rack
84
a
of the rack shaft
84
is made, for example, in the form of a circular arc as shown in FIG.
3
.
The housing
80
has a cylindrical support yoke housing hole
80
a
formed in a perpendicular direction to the rack shaft
84
. Housed inside of the support yoke housing hole
80
a
are a support yoke
85
which supports the rack shaft
84
through a sliding contact member
86
arranged to come in sliding contact directly with the rack shaft
84
, a yoke plug
87
disposed at the back side of the support yoke
85
for closing the support yoke housing hole
80
a,
and a spring
88
interposed, as compressed, between the support yoke
85
and the yoke plug
87
.
The sliding contact member
86
is made of metal or a synthetic resin for receiving load exerted to the support yoke
85
from the rack shaft
84
, and is mounted in a concaved portion formed in the support yoke
85
as shown in FIG.
3
.
The yoke plug
87
is threadedly connected to the end of the support yoke housing hole
80
a
and is fixed to a predetermined position by a lock nut
89
. The support yoke
85
is pushed to the rack shaft
84
by the spring
88
to apply a pre-load across the rack
84
a
and the pinion
83
a.
However, in the above-mentioned conventional rack-pinion type steering apparatus, there are instances where vibration or impact load transmitted to the rack shaft
84
from the steering wheels, causes the rack
84
a
of the rack shaft
84
and the pinion
83
a
of the pinion shaft
83
to shake with respect to each other, thus producing a so-called teeth beating noise. Particularly, in the type in which there is applied, to the rack shaft
84
, a VGR (Variable Gear Ratio) rack in which the gear ratio is lowered from the center toward the both ends, a high load may possibly be transmitted to the support yoke
85
from the rack shaft
84
. Accordingly, the sliding contact member
86
is required to be made of metal. Thus, substantially all contact portions in the support yoke housing hole
80
a
are made of metal. Therefore, the teeth beating noise is successively propagated from the rack shaft
84
to the sliding contact member
86
, the support yoke
85
and the yoke plug
87
, and then transmitted to the outside through the housing
80
. As a result, the conventional rack-pinion type steering apparatus is disadvantageous in that the teeth beating noise is transmitted, as abnormal noise, to the driver, causing the same to be unpleasant.
OBJECT AND SUMMARY OF THE INVENTION
In view of the problem of prior art above-mentioned, it is an object of the present invention to provide a rack-pinion type steering apparatus capable of restraining a teeth beating noise generated due to shaking of the rack and the pinion with respect to each other, from being transmitted, as abnormal noise, to the driver, thus restraining the driver from becoming unpleasant.
To achieve the object above-mentioned, a rack-pinion type steering apparatus according to the present invention comprises:
a housing;
a pinion shaft supported rotatably with respect to the housing and provided at the tip thereof with a pinion;
a rack shaft provided on a lateral side thereof with a rack to be meshed with the pinion;
a support yoke slidably housed in a cylindrical support yoke housing hole formed in the housing for supporting the rack shaft at its back side;
a biasing member of which one end comes in contact with the support yoke for biasing the same toward the rack shaft such that the rack and the pinion are meshed with each other at a predetermined pressure;
a yoke plug attached to the housing for receiving the other end of the biasing member and for closing the support yoke housing hole; and
a damper made of a synthetic resin having at least a pillar-shaped member of which one end and the other end come in contact with the support yoke and the yoke plug, respectively.
In the rack-pinion type steering apparatus of the above construction, there is disposed the damper made of a synthetic resin having at least a pillar-shaped member of which one end and the other end come in contact with the support yoke and the yoke plug, respectively. Accordingly, even though a teeth beating noise is generated due to shaking of the rack and the pinion with respect to each other, the damper can restrain the teeth beating noise from being propagated from the support yoke to the yoke plug, lower the teeth beating noise in noise pressure level, or change the teeth beating noise in noise quality. This restrains the teeth beating noise from being transmitted, as abnormal noise, to the driver, thus restraining the driver from becoming unpleasant.
In the above rack-pinion type steering apparatus, the biasing member is formed by a compression coiled spring disposed at the center portion of the support yoke housing hole, and
the pillar-shaped member is disposed inside of the compression coiled spring, and the damper has a ring-shaped member disposed around the compression coiled spring with one end and the other end of the ring-shaped member coming in contact with the support yoke and the yoke plug, respectively.
In this case, both the pillar-shaped member and the ring-shaped member restrain the teeth beating noise from being propagated. Further, two separate members, i.e., the pillar-shaped member and the ring-shaped member respectively disposed inside and around the compression coiled spring, form the damper. Therefore, it is possible to attach the pillar-shaped member and the ring-shaped member to an existing rack-pinion type steering apparatus using in, for example an automobile without changing the compression coiled spring etc. in this apparatus. Thus, this existing rack-pinion type steering apparatus can readily be improved in the ability of restraining the teeth beating noise.
In the above rack-pinion type steering apparatus, the damper is preferably made of a urethane resin.
In this case, the propagation of the teeth beating noise can be restrained more efficiently because the damper is made of the urethane resin.
In the above rack-pinion type steering apparatus, a belleville spring is preferably interposed between the opposite end surfaces of the support yoke and the yoke plug.
In this case, the belleville spring securely receives the support yoke which tends to swing at an angle with respect to the axial direction of the support yoke housing hole, thus restraining the support yoke from swinging.
In the above rack-pinion type steering apparatus, a metal sheet is preferably interposed between the rack shaft and the support yoke.
In this case, the metal sheet improves the heat-resistant properties and the wear-resistant properties for the rack shaft because the support yoke is not directly rubbed with the rack shaft. Accordingly, even though a high load is exerted to the support yoke from the rack shaft, the support yoke can support the rack shaft without the metal sheet being deformed or molten.
REFERENCES:
patent: 3745850 (1973-07-01), Bayle
patent: 3844181 (1974-10-01), Bayle
patent: 4271716 (1981-06-01), Carduner
patent: 4593578 (1986-06-01), Kobayashi et al.
patent: 4683769 (1987-08-01), Mochizuki et al.
patent: 4788878 (1988-12-01), Morita et al.
patent: 5022279 (1991-06-01), Ueno et al.
patent: 5058448 (1991-10-01), Kiyooka et al.
patent: 5622085 (1
Koyo Seiko Co. Ltd.
Morris Lesley D.
Royal, Jr. Paul
Smith , Gambrell & Russell, LLP
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