JP2003040117A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exert a preload on an engagement area in the state of stably supporting a driving gear for a reduction gear mechanism and to engage the engagement portion, when subjected to the preload, without changing the abutting condition of both teeth of the engagement area. SOLUTION: This electric power steering device comprises a pusher 18a for pushing a hypoid pinion 72 to be linked with the rotation of a steering assisting motor 6 against a hypoid wheel 71 and a support 20 arranged so as to intersect the hypoid pinion 72 in its pushing direction and attached at one side to a steering shaft 4, the support 20 supporting the hypoid pinion 72 at the other side in a double-sided manner and the pusher 18a pushing the support 20.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art The steering of an automobile is arranged outside a vehicle compartment for steering a steering wheel (generally a front wheel) for rotating a steering wheel arranged inside the vehicle compartment. It is performed by telling the steering mechanism.

FIG. 7 is a schematic diagram showing a schematic configuration of an electric power steering device in a conventional example. As an electric power steering apparatus for an automobile, as shown in FIG. 7, a first steering shaft 101 connected to steered wheels 100, the steering shaft 101, and a torsion bar 102 on the steering shaft 101.
Torque sensor 104 that detects steering torque based on the amount of relative displacement in the rotation direction with the second steering shaft 103 that is connected via the torque sensor 104, the torque detected by the torque sensor 104, the vehicle speed, the steering angle of the steered wheels 100, and the like. The torque of the steering assisting motor 105 driven based on
3 and the reduction gear mechanism 106, and the reduction gear mechanism 1
And a housing 107 that accommodates the steering wheel 10.
The operation of the steering mechanism 108 according to the rotation of 0
It is configured to assist with the rotation of 05 to reduce the labor load of the driver for steering.

The reduction gear mechanism 106 includes a hypoid wheel 109 having teeth on one outer peripheral side thereof, and a hypoid pinion 110 meshed with the hypoid wheel 109 and one end of which is integrally connected to a rotating shaft of the motor 105. Or a worm gear having a worm wheel having teeth on its outer periphery and a worm that meshes with the worm wheel and has one end coupled to the rotating shaft 109 of the motor 105. .

When a hypoid gear is used, the clearance between the teeth of the hypoid pinion 110 and the hypoid wheel 109 is initialized during assembly. This initial setting is hypoid pinion 110 and hypoid wheel 10.
It is done by adjusting the axial position of 9
By this adjustment, even if there is a dimensional error in the hypoid gear, the second steering shaft 103, the bearing, etc., the variation in the gap between the teeth is reduced and the backlash is adjusted.

When a worm gear is used, the other end of the worm is made movable in the radial direction and has a pressing body for moving the worm in the radial direction. The pressing body is operated during assembly. The backlash is adjusted by applying a preload to the meshing portion of the worm with the worm wheel.

[0007]

However, in setting the gap between the teeth of the hypoid gear, it is necessary to adjust the axial position of each of the hypoid pinion 110 and the hypoid wheel 109. There was a problem that it was difficult to do.

The clearance between the teeth of the worm gear is set by
Since the pressing body directly moves the worm supported by the housing, there is a problem that the support of the worm on the housing becomes unstable. Also, since this worm moves so as to tilt as a whole centering on one end connected to the rotary shaft of the motor, when preload is applied to the meshing part, the meshing state will change significantly compared to when not preloading. There was also a problem to say.

The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide an electric power steering device capable of applying a preload to the meshing portion in a state in which a drive gear is supported in a stable manner. To do.

Another object of the present invention is to provide an electric power steering apparatus capable of adjusting the preload by reducing the change in the meshing state of the meshing portion when the preload is applied to the meshing portion. .

[0011]

An electric power steering apparatus according to a first aspect of the present invention includes a drive gear rotated by a motor for steering assistance, and a driven gear meshing with the drive gear and connected to a steering mechanism. In the electric power steering device, which is provided with a pressing means for pressing the drive gear toward the driven gear, and is arranged to intersect with the pressing direction of the drive gear, in an electric power steering device configured to assist steering by rotation of the motor. The drive gear is supported on the other side of the support body, one side of which is attached to the mounted body, and the pressing means presses the support body.

According to the first aspect of the invention, since the drive gear is supported on the other side of the support body attached to the attached body on one side, the stability of the drive gear can be improved and the drive gear is supported. Since the pressing means presses the support, the preload of the meshing portion can be adjusted and the backlash can be adjusted by operating the pressing means.

An electric power steering apparatus according to a second aspect of the present invention is characterized in that the support is mounted so as to be movable in a direction in which the pressing means presses.

In the second aspect of the invention, since the entire support can be moved by the pressing means, when the preload is applied to the meshing portion, the change in the contact state between the tooth surfaces at the meshing portion is reduced. The meshing state can be changed, the preload can be adjusted more easily, and the backlash can be adjusted.

The electric power steering apparatus according to the third invention is characterized in that the pressing means are provided at a plurality of positions having different distances from the mounting position of the support body to the mounted body.

In the third aspect of the invention, since the distance from the mounting position of the support body to the mounted body to the pressing means is different at a plurality of positions, by selecting the pressing means, the input applied to the pressing means can be changed. Thus, the preload can be changed.
As a result, it is possible to apply a relatively large preload to the mesh portion with a relatively small input, and to apply a relatively small preload to the mesh portion with a relatively large input.

An electric power steering apparatus according to a fourth aspect of the present invention is characterized in that the supporting body has supporting portions for supporting both ends of the drive gear.

According to the fourth aspect of the invention, since both ends of the drive gear are supported by the support, the stability of the drive gear can be further improved and the entire drive gear is pressed by the pressing means. When the preload is applied to the meshing portion, the meshing state of the teeth in the meshing portion can be further stabilized.

In the electric power steering apparatus according to the fifth aspect of the present invention, the supporting body is a mounting portion to the body to be mounted and a mounting piece having a contacting portion which is continuous with the mounting portion and which the pressing means contacts. It is characterized in that it is provided with two support pieces connected to the contact portion side of the piece and supporting both end portions of the drive gear.

According to the fifth aspect of the invention, the drive gear can be mounted by mounting the mounting portion on the body to be mounted while the both ends of the drive gear are supported by the two support pieces. Can be installed easily.

An electric power steering device according to a sixth aspect of the present invention has a rotary shaft fitted to the center of rotation of the driven gear, and the support is attached to the rotary shaft. And

According to the sixth aspect of the invention, since the rotary shaft fitted to the rotation center of the driven gear also serves as the body to be mounted, a special body to be mounted is unnecessary and the overall size can be reduced. The cost can be reduced.

The electric power steering apparatus according to the seventh aspect of the invention is characterized in that the driven gear is a hypoid wheel having teeth on one surface.

According to the seventh aspect of the invention, since the hypoid pinion can be pressed through the support, the preload of the meshing portion can be easily adjusted by operating the pressing means, and moreover, When a preload is applied to the meshing portion, the meshing state can be changed by reducing the change in the contact state between the tooth surfaces at the meshing portion, the preload adjustment becomes easy, and the backlash adjustment can be easily performed. Also,
Since the axial center of the hypoid pinion can be displaced in the radial direction of the hypoid wheel during assembly, the hypoid gear can be satisfactorily engaged even when there is a dimensional error in the hypoid gear or the like.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings showing the embodiments thereof. First Embodiment FIG. 1 is a schematic diagram showing a schematic configuration of a first embodiment of an electric power steering device according to the present invention.

The electric power steering apparatus has a first steering shaft 2 whose upper end is connected to a steering wheel 1 for steering and a lower end of the first steering shaft 2 which is coaxially connected to the steering wheel 1 for steering. A torsion bar 3 that is twisted by the action of torque, a second steering shaft 4 that is coaxially connected to the lower end of the torsion bar 3, and a first steering shaft and a second steering shaft 4 that correspond to the torsion of the torsion bar. A torque sensor 5 that detects a steering torque applied to the steered wheels 1 based on a relative rotational displacement amount, a steering assist motor 6 that is driven based on the torque detected by the torque sensor 5, and the rotation of the motor 6. A reduction gear mechanism 7 that interlocks and increases the rotational force to transmit the rotation force to the second steering shaft 4, and a housing 8 that houses the torque sensor 5 and the reduction gear mechanism 7 are provided in the housing 8. Motor 6 is attached.

Further, the lower end of the second steering shaft 4 is connected to the pinion shaft 10 via a universal joint 9, and the pinion 10a provided on the pinion shaft 10 and the steering wheels 11, 11 on the left and right sides are steered by the steering mechanism 12, The rack teeth 13a provided on the rack shaft 13 connected via 12 mesh with each other,
The steering operation force generated by the rotation of the steered wheels 1 is transmitted to the rack shaft 13, the rack shaft 13 is moved in the axial direction, and the steering mechanisms 12 and 12 are operated.
The operation of No. 2 is assisted by the rotation of the motor 6 to reduce the labor burden on the driver for steering.

FIG. 2 is a sectional view of the reduction gear mechanism portion, and FIG. 3 is a sectional view taken along line III-III of FIG. The housing 8 is
Upper wall 81a having through hole 81c and upper wall 81a
A housing main body 81 having a substantially cylindrical peripheral wall 81b continuous with the peripheral edge of the housing main body 81, and an annular lid 82 attached to the lower end of the housing main body 81 and having the bearing 14 fitted in the center thereof.
And a substantially tubular bracket 83 attached to one side of the housing body 81, and the motor housing of the motor 6 is attached to the bracket 83.

The bearing 1 is provided around the through hole 81c of the upper wall 81a.
5 is fitted in, and the second steering shaft 4 is rotatably supported by the housing 8 via the bearing 15 and the bearing 14. A bearing 16 for supporting the outer peripheral portion of the hypoid wheel 71 that constitutes the reduction gear mechanism 7 is fitted between the inside of the lower end portion of the housing body 81 and the outer peripheral portion of the lid body 82. Also, the peripheral wall 81b
Has a cutout portion 81d on one side thereof, and the cutout portion 81d
A universal joint 17 for connecting a rotating shaft (not shown) of the motor 6 and a hypoid pinion 72 constituting the reduction gear mechanism 7 is inserted therethrough.

FIG. 4 is a perspective view of the reduction gear mechanism, and FIG. 5 is a side view of the reduction gear mechanism. The reduction gear mechanism 7 includes a metallic hypoid pinion 72 connected to a rotary shaft of a motor 6 via a universal joint 17, a metallic hypoid wheel 71 meshing with the hypoid pinion 72, and the hypoid pinion 72. The pressing means 18 is provided for pressing toward the teeth of the hypoid wheel 71, in other words, toward the teeth of the hypoid wheel 71 in the axial direction of the hypoid wheel 71.

The hypoid wheel 71 is composed of an annular disk having teeth 71a on its outer peripheral surface, and a through hole 71b at the center thereof is fitted and fixed in the middle of the second steering shaft 4. The fixed cylinder 19 fitted to the second steering shaft 4 limits the movement in the axial direction. The outer peripheral portion of the hypoid wheel 71 is supported by the bearing 16.

The hypoid pinion 72 has a shaft portion 72 at both ends.
a, 72b, and both shafts 72a, 72
b is supported by the second steering shaft 4 via a support body 20. Further, one shaft portion 72a is connected to the rotary shaft of the motor 6 via a universal joint 17 formed by using an Oldham's joint.

The support body 20 has an attachment portion 21a to be attached to the second steering shaft 4 by fitting and an abutment portion 21b which is continuous with the attachment portion 21a and abuts against the pressing means 18.
A rectangular mounting piece 21 arranged so as to intersect with the rotation center of the hypoid wheel 71 and a side edge of the abutting portion 21b, which is parallel to the rotation center of the hypoid wheel 71 via bent portions 22a and 23a. And two supporting pieces 22 and 23 facing each other so that
Bearings 24 and 25 are provided at the tips of 2, 23,
The shaft portions 72a and 72b are fitted in the bearings 24 and 25. The mounting portion 21a has a bearing 26 that is fitted to the second steering shaft 4 so as to be movable in the axial direction, and the movement of the mounting portion 21a moves the hypoid pinion 72 toward the hypoid wheel 71. I am trying to get it. The bearings 24, 25, 26 may be rolling bearings such as needle bearings, or may be sliding bearings.

The pressing means 18 is composed of a pressing body 18a that abuts against the abutting portion 21b and presses the supporting body 20 toward the hypoid wheel 71, and a coil spring that urges the pressing body 18a in the pressing direction of the supporting body 20. Elastic body 18b
An adjusting member 18c for adjusting the elastic restoring force of the elastic body 18b is provided, and the adjusting member 18c is a through hole 81c formed in the upper wall 81a of the housing body 81.
The pressing member 18a is screwed to the moving member, and the pressing member 18a is moved via the elastic member 18b by rotating the adjusting member 18c to adjust the pressing force of the pressing member 18a against the contact portion 21b. I can do it.

The pressing means 18 is the second member of the support 20.
It is provided at a plurality of positions having different distances from the mounting position on the steering shaft 4, and any pressing means 18 can be selected and operated.

In the electric power steering apparatus constructed as described above, the hypoid pinion 72 is mounted on the support 20 which is attached to the second steering shaft 4 so as to be movable in the axial direction.
Is supported by both ends, and the support 20 is pressed by the pressing means 18, so that when the reduction gear mechanism 7 is installed in the housing 8, the adjustment member 18
By rotating c, the pressing body 18a presses the support body 20 via the elastic body 18b, the support body 20 moves in the axial direction along the second steering shaft 4, and is supported by the support body 20. Hypoid wheel 71 of hypoid pinion 72
An appropriate preload can be applied to the meshing portion 70 with and the backlash can be adjusted.

This preload can be easily adjusted because only one adjusting member 18c is operated. Moreover, since the hypoid pinion 72 is supported by the support body 20 by both ends, the stability of the hypoid pinion 72 can be improved. Furthermore, when a preload is applied to the meshing portion 70, the entire support body 20 moves in the axial direction along the second steering shaft 4, so that there is less change in the contact state between the tooth surfaces of the meshing portion 70. Thus, the meshing state can be changed, the preload adjustment can be easily performed, and the backlash adjustment can be easily performed.

The pressing means 18 is provided at a position separated from the mounting portion of the support body 20 to the second steering shaft 4, and the hypoid pinion 72 is supported at a position separated from the mounting portion 21a. By operating the pressing means 18, the support body 20 can be pressed with the attachment portion 21a to the second steering shaft 4 as a fulcrum, so that a relatively large preload is applied to the meshing portion 70 with a relatively small operation force. Therefore, the operability of the pressing means 18 is good. In the first embodiment, the second steering shaft 4 constitutes a mounted body or a rotary shaft for mounting the support body 20.

Embodiment 2 FIG. 6 is a perspective view of a reduction gear mechanism of Embodiment 2 of the electric power steering apparatus according to the present invention. The electric power steering apparatus according to the second embodiment uses a reduction gear mechanism 7a including a worm gear instead of the hypoid gear. The reduction gear mechanism 7a includes a worm wheel 7 having teeth on the outer circumference.
3 and a worm 74 that meshes with the worm wheel 73
The support 30 supporting the worm 74, and the worm wheel 73 supporting the worm 74 via the support 30.
Pressed against the teeth of the wheel, in other words the worm wheel 7
The pressing means 18 for pressing the worm wheel 73 in the radial direction toward the teeth of No. 3 is provided.

The worm wheel 73 is the second steering shaft 4
It is fitted and fixed to. Worm 74 has shaft 74 at both ends
a, 74b, and the shaft portions 74a, 74b are rotatably supported by the support body 30. Further, one shaft portion 74a of the worm 74 is connected to the rotary shaft of the motor 6 through the universal joint 17 using an Oldham joint.

The supporting body 30 is connected to a mounting shaft 31 (mounting body) projecting from the inside of the housing 8 by fitting, and is connected to the mounting portion 31a, and the pressing body 18a of the pressing means 18 is connected. Has a contact portion 31b that abuts with, and is arranged in parallel with the center of rotation of the worm wheel 73, and a rectangular mounting piece 31 that is connected to the side edge of the contact portion 31b and has bent portions 32a and 33a. Two support pieces 3 facing each other so as to intersect with the rotation center through
2, 33, and bearings 3 are provided at the tips of the support pieces 32, 33.
4, 35 are provided, and the shaft portions 74a, 74b are fitted to the bearings 34, 35. The mounting portion 31a is designed to be movable in the pressing direction of the worm 74, and the mounted shaft 4
It has a bearing 36 that is fitted to
By moving a, the worm 74 is moved to the worm wheel 73.
It can be moved toward.

The pressing means 18 is the attached shaft 4 of the support 30.
It is provided at a plurality of positions having different distances from the mounting position to 0, and any pressing means 18 can be selected and operated.

In the second embodiment, the pressing means 1 is used.
By rotating the adjusting member 18c of No. 8, the pressing body 18a presses the support body 30 via the elastic body 18b, and the support body 30 moves in the radial direction of the worm wheel 73 along the attached shaft 40. , The engaging portion 7 of the worm 74 supported by the support 30 with the worm wheel 73
It is possible to apply an appropriate preload to 0a and adjust the backlash. Further, when a preload is applied to the meshing portion 70a, the entire supporting body 30 moves in the radial direction of the worm wheel 73, so that the meshing portion 70a is moved.
It is possible to change the meshing state by reducing the change in the contact state between the tooth surfaces in the above, the preload adjustment becomes easy, and the backlash adjustment can be easily performed.

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

In the above-described embodiment, the supports 20 and 30 are attached to the second steering shaft 4 and the attached shaft 40 so as to be movable in the pressing direction of the hypoid pinion 72 and the worm 74. The supports 20, 30 may be swingable with respect to the second steering shaft 4 and the mounted shaft 40,
Further, the hypoid pinion 7 is attached to the mounting portions 21a and 31a side.
2. The worm 74 may be bendable in the pressing direction.

Further, in the embodiment described above, the shaft portion 7 provided at both ends of the hypoid pinion 72 and the worm 74.
2a, 72b, 74a, 74b are supported by the supports 20, 30 to form a double-supported structure. It may be supported.

Further, the reduction gear mechanism 7 of the above-described embodiment is a hypoid gear including a drive gear which is a hypoid pinion 72 and a driven gear which is a hypoid wheel 71, and a drive gear and a worm which are worms 74. It may be a worm gear including a driven gear that is the wheel 73. Further, the reduction gear mechanism 7 may be a bevel gear.

Further, in the embodiment described above, a plurality of pressing means 18 are provided, but in addition, the pressing means 18 may be one. When this pressing means 18 is one,
Since the supports 20 and 30 are configured as in the first and second embodiments, when designed, the position of the pressing means 18 with respect to the mounting portion 21a can be appropriately selected.

[0049]

According to the first aspect of the invention, since the drive gear is supported on the other side of the support body to which one side is attached, the stability of the drive gear can be improved and the drive gear is supported. Since the pressing means presses the support, the preload of the meshing portion can be adjusted by operating the pressing means, and the backlash can be adjusted.

According to the second aspect of the present invention, since the entire supporting member can be moved by the pressing means, when the preload is applied to the meshing portion, the meshing state is changed by reducing the change in the contact state between the tooth surfaces. The state can be changed, preload adjustment becomes easier, and backlash adjustment can be performed easily.

According to the third aspect of the invention, since the distance from the mounting position of the support to the pressing means is different at a plurality of positions, the pressing means is selected so that the preload is made different with respect to the input applied to the pressing means. be able to.

According to the fourth aspect of the invention, since both ends of the drive gear are supported by the support, the stability of the drive gear can be further improved, and moreover, the entire drive gear is pressed by the pressing means. When the preload is applied to the meshing portion, the meshing state of the teeth in the meshing portion can be further stabilized.

According to the fifth aspect of the invention, the drive gear can be mounted by mounting the mounting portion on the body to be mounted while the both ends of the drive gear are supported by the two support pieces. Easy to install.

According to the sixth aspect of the invention, since the rotary shaft fitted to the rotation center of the driven gear also serves as the body to be mounted, a special body to be mounted is unnecessary, and the overall size can be reduced. The cost can be reduced as well.

According to the seventh aspect, since the hypoid pinion can be pressed through the support, the preload of the meshing portion can be easily adjusted by operating the pressing means, and the meshing can be performed. When a preload is applied to the portion, the tooth surfaces can be meshed without changing the contact state of the tooth surfaces in the meshing portion, and the initial contact area of the tooth surfaces can be secured. Further, since the shaft center of the hypoid pinion can be displaced in the radial direction of the hypoid wheel during assembly, the hypoid pinion can be satisfactorily engaged even when there is a dimensional error in the hypoid gear or the like.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a first embodiment of an electric power steering device according to the present invention.

FIG. 2 is a cross-sectional view of a reduction gear mechanism portion in the first embodiment of the electric power steering device according to the present invention.

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

FIG. 4 is a perspective view of the reduction gear mechanism in the first embodiment of the electric power steering device according to the present invention.

FIG. 5 is a side view of the reduction gear mechanism in the first embodiment of the electric power steering device according to the present invention.

FIG. 6 is a perspective view of a reduction gear mechanism in a second embodiment of the electric power steering device according to the present invention.

FIG. 7 is a schematic diagram showing a schematic configuration of an electric power steering device in a conventional example.

[Explanation of symbols]

4 Second steering shaft (attached body, rotating shaft) 6 motor 18 Pressing means 20 Support 21 Mounting piece 21a Mounting part 21b abutting part 22,23 Support piece 30 support 31 Mounting piece 31a mounting part 31b abutting part 32, 33 support pieces 40 Attached shaft (attached body) 71 Hypoid wheel (driven gear) 72 Hypoid pinion (drive gear) 73 Worm wheel (driven gear) 74 Worm (drive gear)

Claims (7)

[Claims] 1. A drive gear that is rotated by a steering assisting motor, a driven gear that meshes with the drive gear and is connected to a steering mechanism, and pressing means that pushes the drive gear toward the driven gear. In the electric power steering device, which assists the steering by the rotation of the motor,
Arranged to intersect the pressing direction of the drive gear,
An electric power steering device, wherein the drive gear is supported on the other side of a support body, one side of which is attached to a mounted body, and the pressing means presses the support body. 2. The electric power steering apparatus according to claim 1, wherein the support is mounted so as to be movable in a direction in which the pressing means presses. 3. The electric power steering apparatus according to claim 1, wherein the pressing means are provided at a plurality of positions having different distances from the mounting position of the support body to the mounted body. 4. The electric power steering apparatus according to claim 1, wherein the support body has support portions that support both ends of the drive gear. 5. The support body is connected to the attachment body and the attachment portion, the attachment piece having a contact portion with which the pressing means abuts, and the attachment piece side of the attachment piece. The electric power steering apparatus according to any one of claims 1 to 4, further comprising: two support pieces that support both ends of the drive gear. 6. The electric power steering apparatus according to claim 1, further comprising a rotating shaft fitted in a rotation center portion of the driven gear, and the supporting body being attached to the rotating shaft. 7. The electric power steering apparatus according to claim 1, wherein the driven gear is a hypoid wheel having teeth on one surface.