JP2003002218A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To forbid that a pushing body is butted to an operation body by an engagement reaction force applied to a driving gear and to eliminate a sound. SOLUTION: An elastic plate 16 is interposed between the pushing body 9 for pushing a worm 71 rotated by a motor 6 for steering assistance toward a worm wheel 72 and the operation body 10 for moving and operating the pushing body 9. It is forbidden by the elastic plate 16 that the pushing body 9 moved by the engagement reaction force is butted to the operation body 10.

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. 10 is a cross-sectional view of a conventional electric power steering apparatus, and FIG. 11 is a cross-sectional view of a reduction gear mechanism portion. As an electric power steering apparatus for an automobile, as shown in FIGS. 10 and 11, for example, a first steering shaft 101 whose upper end is connected to a steering wheel 100 for steering.
And a second steering shaft 103, the lower end of which is coaxially connected to the lower end of the steering shaft 101 via a torsion bar 102, and the lower end of which is connected to a steering mechanism that is connected to a wheel, and a steering wheel 100 is rotated. The torque sensor 104 for detecting the torque applied to the first steering shaft 101 by the twist generated in the torsion bar 102, the steering assisting motor 105 driven based on the detection result of the torque sensor 104, A steering mechanism that is connected to the output shaft of the motor 105 and has a worm 106 and a worm wheel 107 that decelerates the rotation of the output shaft and transmits the decelerated rotation to the second steering shaft 103. The operation of the steering mechanism is assisted by the rotation of the motor 105 to reduce the labor load on the driver for steering.

The worm 106, which constitutes a reduction mechanism, is arranged so as to intersect with the axis of the second steering shaft 103, is supported in the housing 110 via a pair of rolling bearings 108, 108, and the worm wheel 107. The second steering shaft 103 provided with is a pair of rolling bearings 10
It is supported in the housing 110 via 9, 109.

When the speed reducing mechanism is used as described above, the backlash amount of the meshing portion of the worm 106 and the worm wheel 107 is reduced, and the rattling noise due to the backlash at the time of steering is eliminated, so the worm 106 and the worm wheel Worm 10 processed so that the distance between the centers of rotation of 107 and the distance between the centers of the fitting holes into which rolling bearings 108 and 109 are fitted are matched within an allowable range.
6, worm wheel 107, rolling bearings 108, 10
9, the second steering shaft 103, and the housing 110 are selected and assembled, but this assembly requires a lot of time, and improvement measures have been demanded.

FIG. 12 is a sectional view of an essential part of the electric power steering apparatus previously proposed by the applicant of the present invention. The applicant of the present invention has a pressing body 111 which is fitted at the end opposite to the motor of a worm 106 which is rotated by a motor 105 for steering assistance, and which enables the worm 106 to move in the radial direction, and the pressing body 111. An operating body 112 for moving the body 111, and the worm wheel 10 of the worm 106 interposed between the operating body 112 and the pressing body 111.
7. An electric power steering device that includes a coil spring 113 that biases the pressing body 111 in the radial direction to apply a preload to a meshing portion with 7, and reduces a backlash amount by applying a preload to the meshing portion. Was proposed first.

[0007]

However, when the worm gear of the reduction mechanism has its teeth twisted in the direction of rotation with respect to the center line of rotation, when a rotational torque is applied from the worm 106 to the worm wheel 107, in other words, When assisting the steering by the rotation of the motor 105, the worm 10
A component force (hereinafter referred to as a meshing reaction force) is generated so that 6 moves in the radial direction along the teeth of the worm wheel 107, and the mesh reaction force causes the worm 106 to move in the radial direction. When the preload by 113 is relatively small, the worm 10 due to the meshing reaction force is used.
The movement of 6 causes the coil spring 113 to bend, causing the pressing body 111 to come into contact with the operating body 112 and cause noise.

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 apparatus capable of prohibiting the pressing body from abutting against the operating body due to a meshing reaction force. It is in.

Another object of the present invention is to provide an electric power steering apparatus in which the preload applied to the meshing portion can be easily set.

Another object of the present invention is to provide an electric power steering system capable of accurately applying a predetermined preload to the meshing portion.

[0011]

An electric power steering apparatus according to a first aspect of the invention is rotated by a motor for steering assistance, meshes with a drive gear having a shaft portion, and is connected to a steering mechanism. The driven gear and the shaft portion can be moved in the radial direction, and a pressing body that presses the drive gear toward the driven gear by this movement, and an operating body that moves and operates the pressing body are provided. In an electric power steering device that assists steering by rotation of a motor, an elastic plate is interposed between the pressing body and the operating body.

According to the first aspect of the invention, the elastic plate interposed between the pressing body and the operating body urges the drive gear toward the driven gear, and further, the meshing reaction force applied to the drive gear causes the elastic force. Since it is added to the plate, it is possible to prevent the pressing body from coming into contact with the operating body due to the meshing reaction force, and it is possible to eliminate noise.

The electric power steering apparatus according to the second invention is characterized in that the elastic plate is made of rubber or a metallic material. In the second aspect of the invention, the elastic plate is a flat rubber plate or a disc spring or corrugated spring made of a metallic material, and it is necessary to provide a recess for accommodating one end of the coil spring on the end face of the pressing body. Therefore, the processing cost can be reduced as compared with the case where the coil spring is used. Further, since the elastic plate is in contact with the end faces of the pressing body and the operating body over the entire circumference, stability of the pressing body can be improved, and further, a recess for accommodating one end portion of the coil spring is formed on the end face of the pressing body. Since it is not necessary to provide it, the length dimension in the moving direction of the pressing body, by extension, the pressing body side can be made smaller than the case where the coil spring is used, and the space required for incorporating the electric power steering device can be made smaller. The metallic material also includes metallic materials containing inorganic materials such as graphite and ceramics.

An electric power steering apparatus according to a third aspect of the invention is characterized in that the pressing body or the operating body has a recess into which the elastic plate is inserted.

According to the third aspect of the present invention, the elastic plate can be prevented from bending more than a predetermined bending amount by the concave portion, so that the elastic plate is surely damaged even when the meshing reaction force is relatively large. Can be banned.

In the electric power steering apparatus according to the fourth invention, the elastic plate is a ring having a through hole,
A coil spring whose both ends contact the pressing body and the operating body is inserted inside the ring.

In the fourth invention, a coil spring or
Since the coil spring and the elastic plate urge the drive gear toward the driven gear, the amount of movement of the pressing body can be increased as compared with the elastic plate alone, and the preload applied to the meshing portion is set. Further, when the meshing reaction force is relatively large, the movement of the pressing body can be prohibited by the coil spring, so that the elastic plate can be prevented from being damaged.

In the electric power steering apparatus according to the fifth aspect of the present invention, the pressing body is fitted with a sliding bearing in which the shaft portion is fitted at a substantially intermediate position in the moving direction thereof, and is fitted outside the sliding bearing. It has an elastic cylinder.

According to the fifth aspect of the invention, since the shaft portion of the drive gear can be elastically supported by the elastic cylinder regardless of the elastic plate and the coil spring, when the drive gear is moved by the meshing reaction force, It is possible to prevent the slide bearing from contacting the pressing body, and it is possible to eliminate the noise caused by this contact.

The electric power steering apparatus according to the sixth aspect of the invention is characterized in that the pressing body has an elastic tube in which the shaft portion is fitted at a substantially intermediate position in the moving direction thereof.

According to the sixth aspect of the invention, since the shaft portion of the drive gear can be elastically supported by the elastic cylinder regardless of the elastic plate and the coil spring, when the drive gear moves due to the meshing reaction force, It is possible to prevent the shaft portion from coming into contact with the pressing body, and it is possible to eliminate the noise caused by this contact.

An electric power steering apparatus according to a seventh aspect of the invention has a guide member provided with a guide hole for guiding the movement of the pressing body, and the guide member is provided between the pressing body and the operating body in the guide hole. It is characterized by having a hole communicating with the space and exhausting air in the space.

In the seventh invention, when the pressing body moves in the guide hole, the air in the space can be exhausted from the hole to the outside of the space, and the sealing property of the space can be lowered. Therefore, it is possible to smoothly move the pressing body by the elastic plate and accurately apply a predetermined preload to the meshing portion.

[0024]

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 sectional view of a first embodiment of an electric power steering apparatus according to the present invention. The electric power steering device has a first steering shaft 2 having one end connected to a steering wheel 1 for steering and a tubular part at the other end, and the other end of the steering shaft 2 inserted in the tubular part. A torsion bar 3 coaxially connected to the end and twisted by the action of a steering torque applied to the steered wheels 1, and a second steering shaft 4 having the other end coaxially connected to the other end of the torsion bar 3. , A torque sensor 5 for detecting a steering torque applied to the steered wheel 1 based on a relative rotational displacement amount of the first and second steering shafts 2, 4 according to a twist of the torsion bar 3, and the torque sensor 5 detected the torque sensor 5. A steering assisting motor 6 driven on the basis of torque, a drive gear (hereinafter referred to as a worm) 71 that is interlocked with the rotation of the motor 6, decelerates the rotation, and transmits the rotation to the second steering shaft 4 and a driven wheel. Gears (hereinafter worm ho A speed reduction mechanism 7 having Lumpur referred to) 72, and a housing 8 in which the torque sensor 5 and the reduction mechanism 7 is housed, the motor 6 is attached to the housing 8.

The housing 8 has a first accommodating portion 8a for accommodating the torque sensor 5 and a second accommodating portion 8b which is continuous with the accommodating portion 8a and accommodates the worm wheel 72.
And a third accommodating portion 8c which is continuous with the accommodating portion 8b and accommodates the worm 71.

FIG. 2 is a sectional view of the speed reducing mechanism portion, and FIG. 3 is an enlarged sectional view of a main portion. The accommodating portion 8c is elongated in the axial direction of the worm 71, and one end of the accommodating portion 8c faces the inner surface of the concave hole 81 into which the shaft portion 71a provided at one end of the worm 71 is inserted and the inner surface of the concave hole 81. A guide member 83 having a cylindrical guide hole 82 formed in the radial direction of the shaft portion 71a is integrally provided, and a pressing body 9 to be described later is provided on the opening edge side of the guide hole 82 to the outside. An operation body 10 for moving and operating the is screwed. A fitting hole 84 and an annular groove 85 continuous with the fitting hole 84 are provided at the other end of the housing portion 8c, and the retaining ring 12 is fitted in the annular groove 85. Further, the motor 6 having a case communicating with the third housing portion 8c is attached to the housing 8.

The deceleration mechanism 7 includes an output shaft 60 of the motor 6.
And a worm wheel 72 (driven gear) that is fitted and fixed in the middle of the second steering shaft 4 and is connected to the steering mechanism.
1 and the worm wheel 72 mesh with each other so that the output shaft 6
The rotation of 0 is decelerated and transmitted to the second steering shaft 4, and is transmitted from the second steering shaft 4 through a universal joint to, for example, a rack and pinion type steering mechanism (not shown).

The worm 71 is arranged so as to intersect with the axis of the second steering shaft 4, and the shaft portions 71a, 71a,
71b is provided. The shaft portion 71a at one end is inserted into the concave hole 81 and is rotatably supported by the pressing body 9 movably accommodated in the guide hole 82.
The shaft portion 71b at the other end is rotatably supported in the fitting hole 84 via the rolling bearing 11.

The pressing body 9 is formed of a metal material in a cylindrical shape, and has a substantially intermediate position in the axial direction, in other words, a substantially intermediate position in the moving direction along the guide hole 82. A fitting hole 91 penetrating so as to intersect at right angles is formed, and the shaft portion 71a is formed in the fitting hole 91.
Is provided rotatably fitted with a metal slide bearing 14 and a rubber or synthetic resin elastic cylinder 15 fitted on the outside of the slide bearing 14, and the slide bearing 14 and the elastic cylinder 15 are The shaft portion 71a is supported by the pressing body 9 via the shaft portion 71a. A circular recess 92 is provided at one end of the pressing body 9.

An elastic plate 16 for contacting the end surface of the operating body 10 in the concave portion 92 and urging the pressing body 9 in the moving direction so as to apply a preload to the meshing portion of the worm 71 with the worm wheel 72. The one surface side is fitted and held.

The elastic plate 16 is made of a flexible synthetic rubber disc, the thickness of which is made larger than the depth of the recess 92, and the pressing body 9 is attached by elastic restoring force. The pressing body 9 is prohibited from coming into contact with the operating body 10 while being urged. The elastic restoring force of the elastic plate 16 can be appropriately set depending on the thickness, hardness, etc. of the elastic plate.

The operating body 10 has a screw on its peripheral surface, and the screw portion is screwed into the guide hole 82. Further, a rotary operation recess 10 in which a tool is fitted on the side opposite to the elastic plate 16
a.

In the electric power steering apparatus constructed as described above, when the worm 71 is incorporated, the shaft portion 71a of the worm 71 is a sliding bearing via the elastic cylinder 15 provided in the middle of the pressing body 9 in the axial direction. 14 is fitted. Further, by rotating the operating body 10, the pressing body 9 is moved via the elastic plate 16, and further, the worm 71 is moved via the elastic cylinder 15 and the slide bearing 14 to bring the worm 71 into contact with the worm wheel 72. By rotating the worm wheel 72 and confirming that no backlash has occurred, it is possible to eliminate the backlash amount at the meshing portion of the worm 71 and the worm wheel 72. At this time, the elastic plate 16 interposed between the pressing body 9 and the operating body 10 and the elastic cylinder 15 interposed between the pressing body 9 and the slide bearing 14 attach the worm 71 to the worm wheel 72. The worm 71 is urged to apply a preload to the meshing portion of the worm 71 with the worm wheel 72.

With the steering assistance, the worm 71 is pressed in the radial direction so as to follow the teeth of the worm wheel 72. When I joined
The elastic plate 16 for urging the pressing body 9 can suppress the movement of the pressing body 9 due to the meshing reaction force, and can suppress the increase in the amount of backlash.

Further, even when the preload by the elastic plate 16 is relatively small, it is possible to prevent the pressing body 9 from coming into contact with the operating body 10 by the meshing reaction force, so that the noise can be eliminated. Further, the elastic plate 16 is fitted and held in the concave portion 92 of the pressing body 9, and the elastic plate 16 can be restrained from being bent by a predetermined bending amount or more by the concave portion 92. Even when the size is relatively large, it is possible to reliably prevent the elastic plate 16 from being damaged.

Further, since the shaft portion 71a of the worm 71 is supported by the pressing body 9 via the slide bearing 14 and the elastic cylinder 15, when the worm 71 is moved by the meshing reaction force, the sliding bearing 14 is pressed by the pressing body 9. It is possible to prohibit the contact with the elastic tube 15 so that no noise is produced by this contact.

In the first embodiment, the concave portion 92
Is provided on the pressing body 9 instead of being provided on the pressing body 9.
You may provide on the surface facing.

Second Embodiment FIG. 4 is an enlarged cross-sectional view of the essential parts of the second embodiment. In the electric power steering apparatus according to the second embodiment, the depression 92 of the pressing body 9 is eliminated, and the pressing body 9 and the operating body 10 are removed.
The elastic plate 17 is interposed between

The elastic plate 17 is a disc made of synthetic rubber, which is thinner than the thickness of the elastic plate 16.

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.

Third Embodiment FIG. 5 is an enlarged cross-sectional view of the essential parts of the third embodiment. In the electric power steering apparatus according to the third embodiment, instead of using the elastic plate 16 made of synthetic rubber, the elastic plate 16a is made of a metal disc spring or a wave spring, and the elastic plate 16a is made to be the pressing body 9. It is interposed between the operating body 10.

The elastic plate 16a, which is a disc spring, has a through hole in the center and has a disk portion that comes into contact with the end surface of the operating body 10.
It has a taper ring portion which is provided so as to expand from the peripheral edge of the disk portion and is capable of bending, and the end edge of the taper ring portion is in contact with the end surface of the pressing body 9.

The elastic plate 16a made of a wave spring is a disk having a through hole in the center thereof deformed into a corrugated shape in the circumferential direction. The end faces of the pressing body 9 and the operating body 10 are in contact with each other.

In the third embodiment, the disc spring or the wave spring is bent by the rotating operation of the operating body 10, and the disc spring or the wave spring attaches the worm 71 toward the worm wheel 72 via the pressing body 9. It is possible to apply a preload to the meshing portion of the worm 71 with the worm wheel 72.
Further, since the disc spring or the corrugated spring can prevent the pressing body 9 from contacting the operating body 10 due to the meshing reaction force, it is possible to eliminate noise.

Further, since it is not necessary to provide a recess for preventing the coil spring from being displaced, the processing cost can be reduced as compared with the case where the coil spring is used, and
Since the disc spring or the corrugated spring makes contact with the end faces of the pressing body 9 and the operating body 10 over the entire circumference, the stability of the pressing body 9 in the guide hole 82 can be improved, and the end face of the pressing body 9 can be further improved. Since it is not necessary to provide the recessed portion, the length dimension in the moving direction of the pressing body, and hence the guide member portion on the pressing body side can be made smaller than in the case where a coil spring is used, and a space required for incorporating the electric power steering device. Can be made smaller.

Since other configurations and operations are similar to 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.

Fourth Embodiment FIG. 6 is an enlarged cross-sectional view of the essential parts of the fourth embodiment. In the electric power steering apparatus according to the fourth embodiment, the elastic plate 16 made of synthetic rubber is used as a means for urging the pressing body 9.
And a metallic coil spring 18, and the elastic plate 16 and the coil spring 18 are interposed between the pressing body 9 and the operating body 10.

The elastic plate 16 is a circular plate having a through hole in the center thereof, and the coil spring 18 has a smaller diameter than the through hole and has a free length longer than the thickness of the elastic plate 16, and one end side thereof is provided. It is inserted in the through hole.

On the end face of the pressing body 9, there is a deep-bottomed recess 93 in the center and a shallow-bottomed recess 94 around the recessed part 93. The deep-bottomed recess 93 has one end of the coil spring 18. Part of the elastic plate 16 is inserted in the shallow recess 94, and after the coil spring 18 is bent by a predetermined dimension by the rotation operation of the operating body 10, the end surface of the operating body 10 is elastic. The elastic plate 16 is bent together with the coil spring 18 in contact with the other surface of the coil 16.

In the fourth embodiment, since the coil spring 18 and the elastic plate 16 urge the worm 71 toward the worm wheel 72, the moving amount of the pressing body 9 is larger than that of the elastic plate 16 alone. The elastic member 16 and the coil spring 18 can prohibit the movement of the pressing body 9 when the meshing reaction force is comparatively large. Can be eliminated. Further, the elastic plate 16 is fitted and held in the concave portion 94 of the pressing body 9, and the concave portion 94 can restrict the elastic plate 16 from bending more than a predetermined bending amount. Even when the size is relatively large, it is possible to reliably prevent the elastic plate 16 from being damaged.

Since other configurations and operations are the same as those in 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.

Fifth Embodiment FIG. 7 is an enlarged sectional view of the essential parts of the fifth embodiment. The electric power steering apparatus according to the fifth embodiment does not include the shallow recess 94 of the fourth embodiment, and the elastic plate 16 is not provided.
The elastic plate 19 that is thinner than the thickness dimension is used.

The elastic plate 19 is a circular plate having a through hole at the center, one surface of which is in contact with the end surface of the pressing body 9, and the coil spring 18 is inserted into the through hole.

The coil spring 18 has a diameter smaller than that of the through hole and has a free length longer than the thickness of the elastic plate 19, and one end of the coil spring 18 is a recess 9 provided on the end face of the pressing body 9.
It is inserted in 3. Then, after the coil spring 18 is bent by a predetermined dimension by the rotating operation of the operating body 10, the end surface of the operating body 10 comes into contact with the other surface of the elastic plate 19 so that the elastic plate 19 bends together with the coil spring 18.

In the fifth embodiment, since the coil spring 18 and the elastic plate 19 urge the worm 71 toward the worm wheel 72, the moving amount of the pressing body 9 is larger than that of the elastic plate 16 alone. The preload applied to the meshing portion can be easily set, and when the meshing reaction force is relatively large, the pressing body 9 is moved by the coil spring 18.
Therefore, the elastic plate 19 can be prevented from being damaged.

Other configurations and operations are the same as those of the first embodiment.
Since they are the same as those of Nos. 2 and 4, the same parts are denoted by the same reference numerals, and detailed description and operation description thereof will be omitted.

Sixth Embodiment FIG. 8 is an enlarged sectional view of the essential parts of the sixth embodiment. In the electric power steering apparatus according to the sixth embodiment, the elastic cylinder 15 in the first to fifth embodiments is eliminated, and the slide bearing 14 is replaced by an elastic cylinder 15a made of synthetic resin. It is fitted in the fitting hole 91.

In the sixth embodiment, the shaft portion 71a of the worm 71 is supported by the pressing body 9 via the elastic cylinder 15a, and since the elastic cylinder 15a also serves as the slide bearing 14, the meshing reaction force is generated. When the worm 71 moves, the elastic cylinder 15a can prevent the shaft portion 71a from coming into contact with the pressing body 9, and there is no noise caused by the contact at the shaft portion 71a.

Since the other structure and operation are the same as those of the first to fifth embodiments, the same reference numerals are given to the same parts, and the detailed explanation and the explanation of the operation will be omitted.

Seventh Embodiment FIG. 9 is an enlarged cross-sectional view of the essential parts of the seventh embodiment. The electric power steering apparatus according to the seventh embodiment is provided with an exhaust hole 21 that opens in a space 20 between the pressing body 9 and the operating body 10 in the guide hole 82.

The hole 21 is penetrated, for example, from the concave portion 93 of the pressing body 9 in the fifth embodiment to the fitting hole 91, and the air in the space 20 is discharged to the concave hole 81. The holes 21 are formed on the peripheral surface of the pressing body 9 and the operating body 1.
It may be provided in a groove shape on the peripheral surface of 0 or the peripheral surface of the guide hole 82 so as to be elongated in the moving direction of the pressing body 9.

In the seventh embodiment, when the elastic plate 16 is bent by the operating body 10 to move the pressing body 9,
The air in the space 20 can be exhausted from the discharge passage 21 to the concave hole 81, and the sealing property of the space 20 can be lowered, so that the pressing body 9 can be smoothly moved by the elastic plate 16, A predetermined preload can be accurately applied to the meshing portion.

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 fifth and sixth embodiments described above,
The preload applied to the meshing portion is set by bending the coil spring 18 and the elastic plate 19, but in addition, the preload applied to the meshing portion is set by bending the coil spring 18 and is set by the meshing reaction force. Warm 7
When the elastic plate 1 moves, the elastic plate 19 is bent.
The pressing body 9 may be prohibited from coming into contact with the operating body 10 by means of 9.

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

[0066]

As described in detail above, according to the first aspect of the invention, the elastic plate interposed between the pressing body and the operating body urges the drive gear toward the driven gear and further joins the drive gear. Since the mesh reaction force is applied to the elastic plate, it is possible to prevent the pressing body from coming into contact with the operating body due to the mesh reaction force, and it is possible to eliminate noise.

According to the second invention, since the elastic plate is made of a flat rubber plate or a disc spring or a corrugated spring formed of a metallic material, the cost can be reduced and the pressing force can be reduced as compared with the case of using the coil spring. You can improve the stability of the body,
Further, the pressing body side can be downsized, and the space required for incorporating the electric power steering device can be reduced.

According to the third aspect of the invention, since the elastic plate can be restricted from bending more than a predetermined bending amount by the concave portion, the elastic plate is surely prohibited from being damaged even when the meshing reaction force is relatively large. can do.

According to the fourth aspect of the invention, since the coil spring or the coil spring and the elastic plate urge the drive gear toward the driven gear, the moving amount of the pressing body is made larger than that of the elastic plate alone. It is possible to easily set the preload applied to the meshing portion, and when the meshing reaction force is relatively large, the movement of the pressing body can be prohibited by the coil spring.
Damage to the elastic plate can be prohibited.

According to the fifth aspect of the invention, the shaft portion of the drive gear can be elastically supported by the elastic cylinder regardless of the elastic plate and the coil spring, so that when the drive gear moves due to the meshing reaction force, the slip occurs. It is possible to prevent the bearing from coming into contact with the pressing body, and it is possible to eliminate the noise caused by this contact.

According to the sixth aspect of the invention, since the shaft portion of the drive gear can be elastically supported by the elastic cylinder regardless of the elastic plate and the coil spring, when the drive gear is moved by the meshing reaction force, It is possible to prevent the portion from coming into contact with the pressing body, and it is possible to eliminate the noise caused by this contact.

According to the seventh aspect, when the pressing body moves in the guide hole, the air in the space can be exhausted from the hole to the outside of the space. Therefore, the elastic plate can smoothly move the pressing body. Therefore, a predetermined preload can be accurately applied to the meshing portion.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of an electric power steering device according to the present invention.

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

FIG. 3 is an enlarged cross-sectional view of a main part of the electric power steering device according to the present invention.

FIG. 4 is an enlarged cross-sectional view of the essential parts of a second embodiment of the electric power steering device according to the present invention.

FIG. 5 is an enlarged cross-sectional view of the essential parts of a third embodiment of the electric power steering device according to the present invention.

FIG. 6 is an enlarged cross-sectional view of the essential parts of a fourth embodiment of the electric power steering device according to the present invention.

FIG. 7 is an enlarged cross-sectional view of a main part of an electric power steering device according to a fifth embodiment of the present invention.

FIG. 8 is an enlarged cross-sectional view of the essential parts of Embodiment 6 of the electric power steering device according to the present invention.

FIG. 9 is an enlarged cross-sectional view of a main part of an electric power steering device according to a seventh embodiment of the present invention.

FIG. 10 is a sectional view of a conventional electric power steering device.

FIG. 11 is a cross-sectional view of a speed reduction mechanism portion of a conventional electric power steering device.

FIG. 12 is a cross-sectional view of a main part of an electric power steering device previously proposed by the applicant of the present invention.

[Explanation of symbols]

6 motor 8 housing 82 guide hole 83 Guide member 9 pressing body 10 operation body 14 plain bearings 15,15a Elastic tube 16, 17, 19 elastic plate 18 coil spring 20 spaces 21 holes 71 Worm (drive gear) 72 Worm wheel (driven gear)

[Procedure amendment]

[Submission date] June 25, 2001 (2001.6.2)
5)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 12

[Correction method] Change

[Correction content]

[Fig. 12]

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenichiro Aoto             3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka               Koyo Seiko Co., Ltd. (72) Inventor Yoshio Ito             3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka               Koyo Seiko Co., Ltd. F-term (reference) 3D033 CA04                 3J009 DA09 DA11 EA05 EA19 EA23                       EB22 EC05 FA08

Claims (7)

[Claims] 1. Rotated by a motor for steering assistance,
A drive gear having a shaft portion, a driven gear that meshes with the drive gear and is connected to the steering mechanism, and the shaft portion can be moved in the radial direction, and by this movement, the drive gear is directed toward the driven gear. In an electric power steering device including a pressing body to be pressed and an operating body for moving and operating the pressing body, in an electric power steering device configured to assist steering by rotation of the motor, an elastic plate is provided between the pressing body and the operating body. An electric power steering device characterized by being interposed. 2. The electric power steering apparatus according to claim 1, wherein the elastic plate is made of rubber or a metallic material. 3. The electric power steering device according to claim 1, wherein the pressing body or the operating body has a recess into which the elastic plate is inserted. 4. The elastic plate is composed of a ring having a through hole, and a coil spring whose both ends contact the pressing body and the operating body is inserted inside the ring.
4. The electric power steering device according to any one of 3 to 3. 5. The pressing body has a slide bearing in which the shaft portion is fitted at a substantially intermediate position in the moving direction thereof, and an elastic cylinder fitted outside the slide bearing. 1. The electric power steering device according to 1. 6. The electric power steering device according to claim 1, wherein the pressing body has an elastic cylinder in which the shaft portion is fitted at a substantially intermediate position in the moving direction. 7. A guide member provided with a guide hole for guiding the movement of the pressing body, communicating with a space between the pressing body and the operating body in the guide hole, and providing air in the space. The electric power steering apparatus according to claim 1, further comprising a hole for exhausting the air.