JP2001146169A - Electric steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a backlash in an appreciable fashion even if such a part as a small-diameter gear has a dimensional error, the teeth of the small- diameter gear and a larger-diameter gear wear by steering, and the larger- diameter gear of a synthetic resin shrinks under low temperature in winter among others, by automatically decreasing the distance between the centers of rotation of the small-diameter and larger-diameter gears. SOLUTION: The electric steering system comprises a bias ring 20 that has a bias bore 22 in which a bearing 10 is fitted to support in a housing 8 a small- diameter gear 71 synchronizing with the rotation of a motor for assisting steering, and that is radially movable and rotatable, and an elastic body 30 having a plurality of projections 31 for urging the bias ring 20 in the moving direction. A rotation of the bias ring 20 regulates the distance between the centers of rotation of the small-diameter gear 71 and a larger-diameter gear 72, in which regulated state the projections 31 urge the bias ring 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric steering apparatus using a motor as a source of a steering assist force.

[0002]

2. Description of the Related Art In the steering of a motor vehicle, the steering operation of a steering wheel disposed inside a vehicle compartment is performed by turning the steering wheel (generally, a front wheel) outside the vehicle compartment for steering. This is done by telling the steering mechanism.

FIG. 9 is a sectional view of a conventional electric steering apparatus, and FIG. 10 is a sectional view of a speed reduction mechanism. As shown in FIG. 9, a motor-driven steering device for a vehicle includes, for example, a first steering shaft 10 connected to a steered wheel 100 for steering.
1, a second steering shaft 103 whose upper end is coaxially connected to a lower end of the steering shaft 101 via a torsion bar 102, and a lower end of which is connected to a steering mechanism connected to wheels. By rotating, the first steering shaft 101
A torque sensor 104 for detecting the torque applied to the torsion bar 102 by the torsion generated on the torsion bar 102, a steering assist motor 105 driven based on the detection result of the torque sensor 104, and an output shaft of the motor 105,
A speed reduction mechanism having a worm 106 and a worm wheel 107 for reducing the rotation of the output shaft and transmitting the reduced rotation to the second steering shaft 103, wherein the operation of the steering mechanism according to the rotation of the steering wheel 100 is controlled by the motor It is configured to assist by the rotation of 105 and to reduce the labor burden on the driver for steering.

A second steering shaft 103 provided with the worm 106 and the worm wheel 107 is
The housing 11 is provided via a pair of bearings 108 and 109, respectively.
0, which prevents movement in the radial and axial directions.

[0005]

SUMMARY OF THE INVENTION As described above, the worm 1
06 and the worm wheel 107, the backlash occurs at the tooth portion,
Conventionally, when assembling the worm 106 and the worm wheel 107, the worm 106 and the worm 106 are assembled so that the backlash cannot be performed within the range of machining accuracy.
, 108, a housing 110 in which the bearing 108 is fitted, a worm wheel 107, and a second steering shaft 10 that supports the worm wheel 107
A dimensional error such as 3 will cause a relatively large percentage of backlash after assembly.

After assembling the worm 106 and the worm wheel 107, it is necessary to apply a high load to the worm 106 and the worm wheel 107, rotate the worm 106 and the worm wheel 107, and apply a load operation for fitting the meshing portion. In some cases, backlash was newly generated.

In recent years, when the output of the steering assist force has been increased, the worm 106 and the worm wheel 1
There is a problem that the wear of the tooth No. 07 increases and the occurrence of the backlash is unavoidable. In this case, since the movement of the worm 106 and the second steering shaft 103 is prevented, the backlash cannot be adjusted, and the sound due to the backlash leaks into the interior of the automobile.

The applicant of the present invention provides a rotatable bearing case in which a bearing for supporting a worm in a housing is fitted and has a bias hole, and by rotating the bearing case, backlash can be eliminated. Was proposed earlier (Japanese Patent Application No. 11-182525).
issue). In addition, the applicant of the present invention enables the worm supported by the housing to be biased in the direction of the worm wheel, and by providing a leaf spring for biasing the worm from a plurality of circumferential positions in the bias direction, eliminates backlash. An electric steering device capable of performing the above-mentioned operation has been proposed (Japanese Patent Application No. 11-288877).

However, the former electric steering device (Japanese Patent Application No. 11-182525) adjusts the distance between the rotation center of the worm and the worm wheel by turning the bearing case. When the teeth of the wheel wear or the worm wheel made of synthetic resin shrinks due to low temperature in winter or the like, the meshing state changes over time, and when the backlash occurs, the bearing case is turned each time to rotate the bearing case. It is necessary to adjust the center-to-center distance.

Further, the latter electric steering device (Japanese Patent Application No.
No. 288877) has bent pieces at both ends of a curved plate portion, and the bent pieces are brought into contact with the inner surface of the housing to urge the worm from both ends of the leaf spring. When the rotational torque applied to the meshing portion between the worm and the worm wheel is relatively large, the rotational torque causes the worm to move in a direction in which the distance between the rotation centers increases, and the worm comes into contact with an intermediate portion of the leaf spring. Contact noise may occur.

An object of the present invention is to provide an electric steering device which can solve the above problems.

[0012]

An electric steering apparatus according to a first aspect of the present invention includes a small-diameter gear rotatably supported via a bearing in a housing in conjunction with rotation of a steering assist motor. An electric steering device, which includes a large-diameter gear meshed with the small-diameter gear and is attached to a steering shaft disposed non-parallel to the rotation center of the small-diameter gear, and assists steering by rotation of the motor. A biasing ring having a biasing hole into which a bearing is fitted and capable of moving and rotating in the radial direction, and a plurality of protrusions disposed on the outer peripheral side of the biasing ring and biasing the biasing ring in the direction of the movement And an elastic body having:

According to the first aspect of the invention, the distance between the rotation centers of the small-diameter gear and the large-diameter gear can be adjusted by rotating the bias ring, and in this adjusted state, the elastic restoring force of the projection can be reduced. In addition to the small-diameter gear via the bearing, the small-diameter gear can be urged toward the large-diameter gear.Therefore, there is a dimensional error in parts such as the small-diameter gear, and the teeth of the small-diameter gear and the large-diameter gear are rotated by steering. Even when a large-diameter gear made of synthetic resin contracts at low temperatures in winter, etc., the distance between the rotation centers of the small-diameter gear and the large-diameter gear can be automatically reduced, and the backlash is not improved. can do.

In addition, since the plurality of projections urge the bias ring, the displacement of the meshing point between the small diameter gear and the large diameter gear can be prevented well.

An electric steering apparatus according to a second aspect of the present invention is characterized in that it has means for restraining rotation of the biasing ring.

In the second invention, after the bias ring adjusts the distance between the rotation centers of the small-diameter gear and the large-diameter gear, the bias ring rotates by the rotational torque applied to the meshing portion of the small-diameter gear and the large-diameter gear. Can be restrained, and the adjustment state of the distance between the rotation centers can be favorably maintained.

In the electric steering apparatus according to a third aspect of the present invention, the means includes a first engaging portion of the biasing ring, a second engaging portion engaging with the first engaging portion, and A rotating body having an elongated hole along the rotation direction of the bias ring, and a screw body inserted into the elongated hole and screwed to the housing are provided.

According to the third aspect of the present invention, the rotating body can be turned with respect to the screw body inserted into the elongated hole, and the rotating body and the bias ring are connected via the first and second engaging portions. Because of the interlocking, the rotation of the bias ring can be restricted by tightening the screw body, and the bias ring can be turned by loosening the screw body, so that the distance between the rotation centers can be easily reduced. Can be adjusted.

According to a fourth aspect of the present invention, there is provided an electric steering device, wherein the bearing includes a pair in which both ends of the small-diameter gear are fitted, one of the bearings is held by the biasing ring, and the other is connected to one end of the other bearing. The housing is provided with a contact portion that abuts and a screw ring that abuts the other end.

According to the fourth aspect of the present invention, one of the bearings is held by the bias ring, and the other is held by the contact portion and the screw ring, so that the spring body for urging the small diameter gear in the axial direction is provided. Without providing the small-diameter gear, it is possible to favorably prevent the small-diameter gear from rattling in the axial direction, thereby reducing the frictional resistance of the small-diameter gear and improving the steering return of the steered wheels.

According to a fifth aspect of the present invention, there is provided an electric steering device, wherein a small-diameter gear rotatably supported via a bearing in a housing in conjunction with the rotation of a steering assist motor, meshes with the small-diameter gear, In an electric steering device including a large-diameter gear attached to a steering shaft arranged non-parallel to the rotation center of the small-diameter gear, and assisting the steering by rotation of the motor, the bearing may be moved in a radial direction. It is possible to provide an elastic body having three or more projections disposed on the outer peripheral side of the bearing and biasing the bearing from three or more circumferential positions in the direction of the movement.

According to the fifth aspect of the invention, the elastic restoring force of the projection can be applied to the small-diameter gear via the bearing, and the small-diameter gear can be urged toward the large-diameter gear. Even when there is a dimensional error, the teeth of the small diameter gear and the large diameter gear are worn by steering, or the large diameter gear made of synthetic resin contracts at low temperature in winter, etc., the rotation of the small diameter gear and the large diameter gear The distance between the centers can be automatically reduced, and backlash can be effectively eliminated.

In addition, three or more projections come into contact with the bearing,
Since the bearing is urged from the above circumferential position, the displacement of the meshing point of the small-diameter gear and the large-diameter gear can be prevented well, and the small-diameter gear is rotated by the rotating torque applied to the meshing point of the small-diameter gear and the large-diameter gear. Even in the case where a force for moving in a direction in which the distance between the rotation centers is increased is generated,
The movement of the bearing with respect to the elastic body can be restrained by the intermediate projection, and it is possible to prevent the bearing from contacting the elastic body and making a sound.

According to a sixth aspect of the present invention, in the electric steering apparatus, the housing includes means for restraining the elastic body from moving in the circumferential direction of the bearing.

According to the sixth aspect of the present invention, since the elastic body can be restrained from moving in the circumferential direction of the bearing by the rotational torque applied to the meshing portion between the small diameter gear and the large diameter gear, the meshing point of the small diameter gear and the large diameter gear can be restrained. Can be prevented satisfactorily.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. Embodiment 1 FIG. 1 is a sectional view showing a configuration of an electric steering device according to the present invention. The electric steering device includes a first steering shaft 2 having one end connected to a steered wheel 1 for steering and a cylindrical portion at the other end;
A torsion bar 3 is inserted into the cylindrical portion, one end of which is coaxially connected to the other end of the steering shaft 2 and is twisted by the action of a steering torque applied to the steered wheels 1. A second steering shaft 4 inserted around and coaxially connected at the other end to the other end of the torsion bar 3
And a first and a second corresponding to the torsion of the torsion bar 3.
The steering wheel 1 is determined by the relative rotational displacement of the steering shafts 2 and 4.
A torque sensor 5 for detecting a steering torque applied to the motor, a steering assist motor 6 driven based on the torque detected by the torque sensor 5, and a rotation speed of the motor 6 A speed reduction mechanism 7 having a small diameter gear (hereinafter referred to as worm) 71 and a large diameter gear (hereinafter referred to as worm wheel) 72 for transmitting to the second steering shaft 4, and a housing accommodating the torque sensor 5 and the speed reduction mechanism 7 8
The motor 6 is attached to the housing 8.

The housing 8 has a first housing 8a for housing the torque sensor 5 and a second housing 8b continuous with the housing 8a and housing the worm wheel 72.
And a third accommodating portion 8c which is continuous with the accommodating portion 8b and accommodates the worm 71. The accommodation portion 8c penetrates in the axial direction of the worm 71, a first fitting hole 81 is provided at one end thereof, and a second fitting hole 82 and a continuous with the fitting hole 82 at the other end. A screw hole 83 is provided, and the screw ring 13 is screwed into the screw hole 83. The second fitting hole 82 is provided with a contact portion 84 with which one end of a second bearing described later contacts.

The first fitting hole 81 is provided with a pair of concave locking portions 85, 85 at an interval of about 120 ° on the worm wheel 72 side with respect to the center thereof (see FIG. 3). First
Four screw holes 86 are equally arranged at the hole edge of the fitting hole 81. The screw 9 is screwed into these screw holes 86 so that a rotating body described later can rotate on the housing 8. Mounted. The motor 6 having a case communicating with the third housing portion 8c is attached to the housing 8.

FIG. 2 is a sectional view of the speed reduction mechanism. The speed reduction mechanism 7 includes a worm 71 having a shaft 71 a connected to the output shaft 60 of the motor 6, and a worm wheel 72 fitted and fixed in the middle of the second steering shaft 4. The rotation of the output shaft 60 is reduced and transmitted to the second steering shaft 4 by the engagement of the wheel 72,
The power is transmitted from the second steering shaft 4 via a universal joint to, for example, a rack and pinion type steering mechanism (not shown).

The worm 71 is disposed so as to intersect with the axis of the second steering shaft 4. The shaft 71 a at one end of the worm 71 has the first bearing 10, the bias ring 20 for holding the bearing 10,
The elastic member 30 is disposed on the outer peripheral side of the bias ring 20 and biases the bias ring 20 from a plurality of circumferential positions in the radial direction. The shaft ring 71a at the other end is rotatably supported by the second fitting hole 82 of the housing portion 8c via the second bearing 11, and the screw ring 13 screwed into the screw hole 83 is provided. The screw ring 13 and the contact portion 8 contact the outer ring of the second bearing 11.
4 restricts the movement of the second bearing 11 in the axial direction. The shaft 71 a at the other end is spline-fitted to the inner surface of the connecting cylinder 12 and connected to the output shaft 60.

The worm wheel 72 is mounted on the worm 7
An annular tooth portion made of a synthetic resin having a plurality of teeth meshing with one another, and a metal boss portion fitted by injection molding into the annular tooth portion are provided at a center portion of the boss portion. A through hole is fitted to the second steering shaft 4.

FIG. 3 is a sectional view taken along the line III--III in FIG.
Is a left side view of FIG. 2, and FIG. 5 is a front view of the elastic body. The biasing ring 20 includes a fitting portion 21 fitted to the first fitting hole 81 so as to be able to move and rotate in the radial direction, and a biasing hole 22 biased to the center of the fitting portion 21. The first bearing 10 is fitted in the bias hole 22;
At three circumferential positions between the fitting portion 21 and the bias hole 22,
First through-holes 23 are provided, and are rotated by an operating body 40 having a second engaging portion 41 that engages with these through-holes 23.

The operating body 40 is provided with the first fitting hole 81
A disc-shaped closing portion 42 rotatably inserted into the fitting hole 81 to close a hole edge of the fitting hole 81, and a flange 43 connected to an outer periphery of the closing portion 42, and provided on an inner surface of the closing portion 42. The first
Pin-shaped second engagement portion 4 inserted into engagement portion 23
1 are protruded, and four positions along the rotation direction are provided at four positions of the flange 43 corresponding to the screw holes 86.
The long holes 44 are equally arranged, and the screw bodies 9 inserted into the long holes 44 are fixed to the housing 8 by screwing into the screw holes 86. The elastic restoring force of the protrusions 31 provided on the elastic body 30 is applied to the biasing ring 20 between the first and second engaging portions 23 and 41 while the operating body 40 is fixed. Is provided with a slight gap.

The elastic body 30 is commercialized under the trade name of a tolerance ring (manufactured by Rencor Tolerance Ring Co.), and is provided between both ends of a thin metal plate having elasticity such as a leaf spring. And a plurality of protrusions 31 having a semicircular cross section are provided at predetermined intervals. The protrusions 31 are formed in a ridge that is substantially perpendicular to both sides except for both sides between both ends of the metal plate, but are also formed in a ridge on both sides without leaving both sides. And may have a semi-circular cross-section or a substantially V-shaped cross-section. The elastic body 30 is disposed between the biasing ring 20 and the first fitting hole 81, is entirely curved, and almost all of the projections 31.
And urges the worm 71 to the point of engagement with the worm wheel 72 by the elastic deformation of the projections 31.

The elastic body 30 is formed to have a length of about ／ of the circumference, in other words, a length curved at about 240 °, and the notch 30a having a length of about ３ of the circumference has a worm. Wheel 7
The bias ring 20 is biased from a circumferential position between both ends. Also, bent pieces 32, 32 are provided at both ends of the elastic body 30, and these bent pieces 32, 32
A pair of locking portions 8 provided in the first fitting hole 81
The movement of the elastic body 30 in the circumferential direction is restrained by being locked to 5, 85.

In the first embodiment, when the worm 71 is incorporated, the elastic body 30 curved in the first fitting hole 81 of the housing 8 and the bias ring 20 in which the first bearing 10 is fitted in the bias hole 22. Is inserted, and the bent pieces 32 of the elastic body 30 are inserted.
The operating body 40 in which the second engagement portion 41 is engaged with the first engagement portion 23 is inserted into the first fitting hole 81 while the second engagement portion 41 is engaged with the engagement portions 85, 85. Insert the operation body 40 into the slot 4
The worm 71 is inserted from the second fitting hole 82 into the third housing portion 8c in a state where the worm 71 is attached to the housing 8 by screwing the screw bodies 9 to be inserted into the screw holes 86 into the screw holes 86. The first bearing 11 is fitted and supported on the first bearing 10, and the second bearing 11 is fitted on the second fitting hole 82 and the other end 71 a of the worm 71 to form a screw ring. 13
Is screwed into the screw hole 83 to sandwich the outer ring of the second bearing 11 between the contact portion 84 and the screw ring 13.
1 is restricted from moving in the axial direction.

Thereafter, by rotating the operating body 40, the bias ring 20 is turned to change the radial position of the first bearing 10, and the worm 71 fitted to the bearing 10 is transferred to the worm wheel 72. And the distance H between the rotation centers of the worm 71 and the worm wheel 72 can be adjusted.

Therefore, when the worm 71 is incorporated,
The distance H between the rotation centers can be easily set without being affected by dimensional errors of components such as the worm 71. Further, the second bearing 11 is provided on the contact portion 84 of the housing 8.
In addition, since the movement in the axial direction is restricted by the screw ring 13, it is possible to favorably prevent the worm 71 from rattling in the axial direction without providing a spring body for urging the worm 71 in the axial direction. Can be. Therefore, the frictional resistance of the worm 71 can be reduced, and the steerability of the steered wheels can be improved.

Also, by incorporating the worm 71, the projections 31 of the elastic body 30 bend, and the projections 31 bias the worm 71 toward the worm wheel 72 via the bias ring 20 and the first bearing 10. Because of the warm 71
And the amount of wear of the teeth of the worm wheel 72 increases,
When the large-diameter gear 72 made of synthetic resin contracts due to low temperature in winter or the like, and the meshing state changes over time,
The distance H between the rotation centers can be automatically adjusted by the elastic restoring force of the projections 31. In this case, protrusion 3
The biasing ring 20 to which the elastic restoring force of 1.
It moves within a movement range of a slight gap provided between the second engagement portions 23 and 41, and the distance H between the rotation centers can be automatically adjusted.

In this case, when the distance H between the centers of rotation cannot be satisfactorily adjusted only by the elastic restoring force of the projections 31, the screws 9 are relaxed and
By rotating the biasing ring 20 through the first bearing 1
0, the worm 71 fitted to the bearing 10 can be moved toward the worm wheel 72, and the distance H between the worm 71 and the rotation center of the worm wheel 72 can be adjusted well. it can.

In addition, almost all the projections 31 of the elastic body 30.
Abuts against the biasing ring 20 and urges the bearing 10 from a circumferential position of about 240 °, so that the displacement of the mesh point of the worm 71 and the worm wheel 72 can be prevented well, and the worm 71 and the worm wheel 72 Even when the rotational torque applied to the meshing point generates a force to move the worm 71 in the direction in which the distance H between the rotation centers increases, the bearings 1 are provided by the intermediate projections 31.
The movement of the zero and the biasing ring 20 with respect to the elastic body 30 can be restrained, and the biasing ring 20 can be prevented from contacting the elastic body 30 and sounding.

FIG. 6 is a sectional view showing an embodiment incorporating another elastic body. In the first embodiment, the elastic body 30
6 may be bent at right angles to be bent pieces 32, 32, or may be bent to bend both ends, as shown in FIG. In this case, for example, the first fitting hole 81 is formed to have a large diameter within a range of about 120 ° on the worm wheel 72 side with respect to the center thereof, and the bent pieces 32, 32 are formed at both circumferential ends of the large diameter portion. Engaging part 8 with which
7, 87 are provided to restrict the movement of the elastic body 30 in the circumferential direction.

Embodiment 2 FIG. 7 is a sectional view of a speed reduction mechanism according to Embodiment 2, and FIG. 8 is a sectional view taken along line VIII-VIII in FIG. Embodiment 2
In the electric steering device, the biasing ring 20 and the operating body 40 are eliminated, the first bearing 10 can be moved in the radial direction, and the elastic body 30 is disposed between the bearing 10 and the first fitting hole 81. Almost all the projections 31 of the elastic body 30 are
And urges the first bearing 10 from three or more circumferential positions in the direction of the movement by the elastic deformation of the protrusions 31, and urges the worm 71 to the point of engagement with the worm wheel 72.

The first fitting hole 81 of the housing 8 is formed to have a large diameter within a range of about 120 ° on the worm wheel 72 side with respect to the center thereof, and the elastic body 30 is bent at both circumferential ends of the large diameter portion. Locking portions 87, 87 with which the pieces 32, 32 abut are provided.

As described above, the elastic body 30 is about 2/1/2 of the circumference.
3 is formed at a length curved in about 240 degrees, in other words, a notch 30a having a length of about 1/3 of its circumference is formed on the outer peripheral side of the bearing 10 so as to be on the worm wheel 72 side. The bent pieces 32, 32 provided at both ends are
A pair of the locking portions 87 provided in the fitting holes 81 of the
The engagement of the elastic member 87 restrains the elastic body 30 from moving in the circumferential direction.

Since other structures and operations are the same as those of the first embodiment, the same parts are denoted by the same reference numerals.
The detailed description and the description of the operation will be omitted.

In the second embodiment, when the worm 71 is incorporated, the curved elastic body 30 and the first bearing 10 are inserted into the first fitting hole 81 of the housing 8, and the bent piece of the elastic body 30 is inserted. The worm 71 is inserted into the third housing portion 8c from the second fitting hole 82 in a state where the worms 32 are locked to the locking portions 87, 87, and one end side shaft portion 71a of the worm 71 is inserted.
To the first bearing 10, the second bearing 11 is fitted to the second fitting hole 82 and the other end side shaft portion 71 a of the worm 71, and the screw ring 13 is screwed into the screw hole 83. By attaching the worm 71, the movement of the worm 71 in the axial direction is restricted.

The elastic body 30 that urges the built-in worm 71 has almost all the projections 31 contact the bearing 10 and urges the bearing 10 from a circumferential position of about 240 °. And the displacement of the mesh point of the worm wheel 72 can be prevented well, and the worm 71
Also, even when the rotational torque applied to the meshing point of the worm wheel 72 generates a force for moving the worm 71 in the direction in which the distance H between the rotation centers increases, the elastic members 30 of the bearing 10 are provided by the intermediate projections 31. Can be restrained, and the bearing 10 can be prevented from contacting the elastic body 30 and sounding.

Therefore, when the worm 71 is incorporated,
The distance H between the rotation centers can be easily set without being affected by dimensional errors of components such as the worm 71. Further, the second bearing 11 is provided on the contact portion 84 of the housing 8.
In addition, since the movement in the axial direction is restricted by the screw ring 13, it is possible to favorably prevent the worm 71 from rattling in the axial direction without providing a spring body for urging the worm 71 in the axial direction. Can be.

Since the projections 31 of the elastic body 30 urge the worm 71 toward the worm wheel 72 via the first bearing 10, the amount of wear of the teeth of the worm 71 and the worm wheel 72 increases. When the engagement state changes over time due to shrinkage of the synthetic resin worm wheel 72 due to low temperature in winter, etc., the protrusions 31.
The distance H between the rotation centers can be automatically adjusted by the elastic restoring force.

In the first and second embodiments, the elastic member 3
0 may be formed to have a length that bends at about 240 °, or may be made to have a length that bends at about 120 °, for example, as long as it can be bent.

The reduction mechanism 7 of the first and second embodiments described above is a worm gear having a small gear 71 as a worm and a large gear 72 as a worm wheel, and a small gear 71 as a hypoid pinion. And a hypoid gear provided with a large gear 72 that is a hypoid wheel.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an electric steering device according to the present invention.

FIG. 2 is a sectional view of a speed reduction mechanism of the electric steering device according to the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a left side view of FIG. 2;

FIG. 5 is a front view of an elastic body of the electric steering device according to the present invention.

FIG. 6 is a sectional view showing an embodiment in which another elastic body is incorporated in the electric steering device according to the present invention.

FIG. 7 is a sectional view of a speed reduction mechanism in a second embodiment of the electric steering apparatus according to the present invention.

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a sectional view of a conventional electric steering device.

FIG. 10 is a cross-sectional view of a reduction mechanism of a conventional electric steering device.

[Explanation of symbols]

 Reference Signs List 4 steering shaft 6 motor 7 reduction mechanism 71 small-diameter gear 72 large-diameter gear 8 housing 85, 87 locking section 9 screw body 11 bearing 13 screw ring 20 bias ring 22 bias hole 23 first engagement section 30 elastic body 31 protrusion 32 Folded piece 40 Operation body 41 Second engaging part 44 Slot

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kaname Shiro 3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka F-term (reference) 3D033 CA04

Claims (6)

[Claims] 1. A small-diameter gear rotatably supported via a bearing in a housing in conjunction with the rotation of a steering assist motor and meshed with the small-diameter gear, and are arranged non-parallel to the rotation center of the small-diameter gear. A large-diameter gear attached to a steering shaft to be driven, wherein the steering is assisted by the rotation of the motor. A motor-driven steering system comprising: a rotatable bias ring; and an elastic body disposed on an outer peripheral side of the bias ring and having a plurality of protrusions for urging the bias ring in the direction of the movement. apparatus. 2. An electric steering apparatus according to claim 1, further comprising means for restricting rotation of said biasing ring. 3. The means comprises a first engaging portion of the biasing ring, a second engaging portion engaged with the first engaging portion, and an elongated hole along a rotation direction of the biasing ring. The electric steering device according to claim 2, further comprising: a rotating body having: a screw body inserted into the elongated hole and screwed to the housing. 4. The bearing has a pair of fittings to which both ends of the small-diameter gear are fitted. One bearing is held by the biasing ring, and a contact portion that contacts one end of the other bearing and a contact portion that contacts the other end. The screw ring which contacts is provided in the said housing.
An electric steering device as described in the above. 5. A small-diameter gear rotatably supported via a bearing in a housing in conjunction with rotation of a steering assist motor and meshing with the small-diameter gear, and arranged in a non-parallel to a rotation center of the small-diameter gear. In a motor-driven steering device comprising a large-diameter gear attached to a steering shaft to be driven and assisting steering by rotation of the motor, the bearing is movable in a radial direction, and is provided on an outer peripheral side of the bearing. 3 bearings arranged
An electric steering device comprising an elastic body having three or more projections for urging in the direction of the movement from the circumferential position. 6. The electric steering apparatus according to claim 5, wherein the housing has means for restricting movement of the elastic body in a circumferential direction of the bearing.