Motor vehicles – Steering gear – With electric power assist
Reexamination Certificate
2000-12-06
2003-05-13
Morris, Lesley D. (Department: 3611)
Motor vehicles
Steering gear
With electric power assist
C074S3880PS
Reexamination Certificate
active
06561306
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electric steering apparatus using a motor as a source of generating a steering assist force.
An automobile is steered by transmitting a rotational operation of a steering wheel disposed inside the compartment of the vehicle to a steering mechanism provided outside of the compartment for steering-control wheels (in general, front wheels).
FIG. 1
is a cross-sectional view of an electric steering apparatus according to a conventional example.
As illustrated in
FIG. 1
, an electric steering apparatus for an automobile comprises a first steering shaft
101
connected to a steering wheel; a torque sensor
104
for detecting a steering torque by relative displacement in a rotating direction between the steering shaft
101
and a second steering shaft
103
connected to the steering shaft
101
through a torsion bar
102
; and a reduction mechanism
108
including a hypoid pinion
106
for increasing a torque of a steering assisting motor
105
driven based on a torque detected by the torque sensor
104
and for transmitting the increased torque to the steering shaft
103
and a hypoid wheel
107
meshing with the hypoid pinion
106
, and is arranged to assist the operation of the steering mechanism corresponding to the rotation of the steering wheel by rotation of the motor
105
so as to reduce a driver's labor for steering.
The hypoid pinion
106
is integrally coupled to one end portion of a rotating shaft
109
of the motor
105
. Moreover, movement of the hypoid pinion
106
in a radial direction and in an axial direction is inhibited by a pair of bearings
110
and
111
supporting both end portions of the rotating shaft
109
, while a pair of bearings
112
and
113
prevent the second steering shaft
103
to which the hypoid wheel
107
is attached from moving in a radial direction and in an axial direction.
By the way, in the case where the hypoid pinion
106
and hypoid wheel
107
are used, the clearance between the teeth of the hypoid pinion
106
and hypoid wheel
107
is initially set in assembling. At this initial setting, a variation of the clearance between the teeth is caused by dimensional errors of parts, such as the hypoid pinion
106
, bearings
110
through
113
, hypoid wheel
107
and second steering shaft
103
, and the accuracy of the crossing angle in assembling. Consequently, backlash occurs after the assembling, and noise caused by this backlash will be heard inside the compartment of the automobile.
Further, with the progress in an increase of the power of the steering assist force in resent years, the abrasion of the teeth of the hypoid pinion
106
and hypoid wheel
107
increases and a problem arises that occurrence of the above-mentioned backlash is unavoidable. In this case, since the movements of the hypoid pinion
106
and hypoid wheel
107
are inhibited, the backlash can not be adjusted and consequently noise caused by the backlash will be heard inside the compartment of the automobile.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide an electric steering apparatus capable of solving the above problems.
An electric steering apparatus according to the first invention is an electric steering apparatus for assisting steering by rotation of a motor, comprising: a driving gear provided on a supporting shaft which operates with rotation of the motor for assisting steering; a driven gear meshing with the driving gear; a steering shaft to which the driven gear is provided; and a first bearing for supporting the supporting shaft; and characterized in that the driving gear can deflect in the radial direction, and deflecting means for deflecting the driving gear in its deflecting direction is comprised.
An electric steering apparatus according to the second invention is characterized, in addition to the first invention, in that the deflecting means includes an elastic member having at least three protrusions for energizing the driving gear in the deflecting direction from at least three positions along a circumferential direction.
An electric steering apparatus according to the third invention is characterized, in addition to the first invention, in that the driving gear is able to swing with the first bearing as a fulcrum.
An electric steering apparatus according to the fourth invention is characterized, in addition to the third invention, in that the deflecting means includes an elastic member having at least three protrusions for energizing the driving gear in the deflecting direction from at least three positions along a circumferential direction.
An electric steering apparatus according to the fifth invention is characterized, in addition to the third invention, in that the supporting shaft is a rotating shaft of the motor, and one end portion of the supporting shaft is supported so that it is able to swing with the first bearing as a fulcrum, the other end portion of the supporting shaft of the motor is supported by a second bearing which is deflectable in a radial direction, and the driving gear is integrally coupled to the one end portion of the rotating shaft.
An electric steering apparatus according to the sixth invention is characterized, in addition to the fifth invention, in that the deflecting means is interposed between the second bearing and a housing for holding the second bearing.
An electric steering apparatus according to the seventh invention is characterized, in addition to the fifth invention, in that the deflecting means includes an elastic member having at least three protrusions for energizing the driving gear in the deflecting direction from at least three positions along a circumferential direction.
An electric steering apparatus according to the eighth invention is characterized, in addition to the third invention, in that both end portions of the rotating shaft of the motor are supported by a pair of third bearings, and the driving gear is coupled to one end portion of the rotating shaft through a universal joint.
An electric steering apparatus according to the ninth invention is characterized, in addition eighth invention, in that the deflecting means includes an elastic member having at least three protrusions for energizing the driving gear in the deflecting direction from at least three positions along a circumferential direction.
An electric steering apparatus according to the tenth invention is characterized, in addition to the eighth invention, in that the driving gear is supported by a fourth bearing interposed between the first bearing and the universal joint so that it is deflectable in a radial direction, and the deflecting means is an elastic member for energizing the fourth bearing in its deflecting direction.
An electric steering apparatus according to the eleventh invention is characterized, in addition to the first invention, by further comprising fifth and sixth bearings made of iron for limiting movement of the driven gear in an axial direction; and an elastic member, interposed between the fifth bearing and a housing made of aluminum into which the fifth and sixth bearings are fitted, for energizing the fifth bearing toward the driven gear, and in that the driven gear is formed by using a hypoid wheel.
According to the first invention, since the driving gear can be deflected toward the driven gear by the deflecting means, it is possible to satisfactorily eliminate backlash without being affected by dimensional errors of parts such as the driving gear and the accuracy of the crossing angle in assembling and to improve the yield. Moreover, even when the meshing state of the driving gear and driven gear changes with time because of abrasion of the teeth of the driving gear and driven gear due to steering, it is possible to satisfactorily eliminate backlash and to prevent noise from being generated by backlash and heard inside the compartment of an automobile.
According to the third invention, in the first invention, it is possible to eliminate backlash without changing the supporting point of the driving gear
Joshita Kaname
Ougita Shingo
Sugiura Tomonori
Takagi Yoshiaki
Watanabe Masayuki
Birch & Stewart Kolasch & Birch, LLP
Koyo Seiko Co. Ltd.
Lum L.
Morris Lesley D.
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