JP2003341531A - Auxiliary steering force transmitting mechanism for electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration due to abrasion of a connection part of a joint member and both shafts by applying a means for avoiding axial move ment to a joint member connecting an electric motor rotation shaft outputting an auxiliary steering force with a gear shaft of a gear transmission mechanism, and suppressing rottling accompanied with the axial movement of the joint member, in an electric power steering device. <P>SOLUTION: The auxiliary steering force from the rotating shaft 1 of an electric motor 4 is transmitted to a worm shaft 2 of a worm gear mechanism 5 via a joint member 3. The joint member 3 is coupled with the motor rotating shaft 1 via a torque limiter 3a, and the worm gear mechanism 5 is coupled with the worm shafted through a serration 3b. The joint member 3 is prevented from axially moving to the motor rotating shaft 1 by a ring R<SB>1</SB>such as a C- shaped ring. <P>COPYRIGHT: (C)2004,JPO

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 used in an automobile or the like, and more particularly to a rattling prevention structure for a joint member connecting an electric motor rotating shaft and a gear shaft of a gear transmission mechanism, By applying the rattling prevention structure to the joint member, axial movement due to rattling of the joint member is prevented, and the joint portion of the joint member and the electric motor rotating shaft and the gear shaft of the gear transmission mechanism is connected. A device for preventing wear and deterioration.

[0002]

2. Description of the Related Art In an electric power steering system, means for avoiding direct input of torque to an electric motor when unexpectedly large torque is input due to kickback or the like from the road surface. It is well known to provide, and as a means for that, a torque limiter is provided at the connecting portion of the joint member that connects the electric motor rotating shaft and the gear shaft of the gear transmission mechanism, and the torque limiter is provided at the time of the excessive torque input. A joint part structure of the joint member is known in the prior art in which a torque limiter imparts rotation due to relative slip between the shafts to interrupt torque transmission between the shafts to protect the electric motor. ing.

An example of a concrete structure of the joint member for connecting the conventional electric motor rotating shaft and the gear shaft of the gear transmission mechanism and the connecting portion will be described based on Japanese Patent Laid-Open No. 2002-46633, including its peripheral structure. The outline is as follows.

That is, as shown in FIGS.
A worm gear mechanism 05 is shown as a gear transmission mechanism that is an auxiliary steering force transmission mechanism.
The auxiliary steering force from is transmitted to the output shaft of the steering mechanism via the worm wheel 05b that meshes with the worm 05a. Worm shaft 02 to which the worm 05a is attached
Is rotatably supported by the bearings 02a and 02b in the vicinity of both ends of the housing 0H, and one end thereof is connected to the rotary shaft 01 of the electric motor 04 via the joint member 03.

The connection between the electric motor rotating shaft 01 and the worm shaft 02 via the joint member is, as apparent from FIG. 7, the electric motor at one end of the joint member 03 (to the left of the joint member 03). Rotating shaft 01
And a torque limiter between the other end of the joint member 03 (on the right side of the joint member 03) and the worm shaft 02, which is capable of sliding in the axial direction while transmitting rotational torque to each other via serrations 03b. The connection is made to allow relative rotation of each other when an excessive torque is input via 03a.

As the torque limiter 03a, usually,
An elastic ring member 03a1 having a corrugated plate-shaped ridge as shown in FIG. 8 which is an example of a cross-sectional view taken along line 0A-0A of FIG.
Is sandwiched between the outer peripheral surface of the worm shaft 02 and the inner peripheral surface of the joint member 03, and the elastic frictional force due to the clamping deformation of the ridge causes the members 02 and 03 to be press-bonded to each other. If the transmission torque is within a predetermined value, the elastic frictional force causes both members 0
The two and 03 rotate integrally without slipping each other, but when the transmission torque exceeds the predetermined value, the elastic frictional force is surpassed and the two members 02 and 03 slide relative to each other. It is a thing.

By the way, in the connecting portion between the joint member 03 and both the shafts thereof, the fluctuation force of the rotational torque from the electric motor rotary shaft 01 and the worm shaft 02 and the fluctuation force in the axial direction (thrust force) are constantly repeated. The joint member 03 and its connecting portion under such adverse conditions are operated under severe conditions such as excessive rotational torque or axial impact force. It is difficult to secure sufficient durability, and in particular, the torque limiter 03a having the above-described structure in the connecting portion causes plastic deformation such as crushing of the ridges and elastic fatigue gradually under the severe conditions as described above. When the frictional force disappears, the connection between the worm shaft 02 and the joint member 03 may be loosened due to the elastic frictional force, and the looseness of the connection may cause looseness of the joint member 03. It will invite you.

Occurrence of rattling in the joint member 03 causes various problems such as an unstable state of the slip setting load by the torque limiter 03a. There is axial movement due to rattling.

By the way, the movement of the joint member 03 in the axial direction due to the occurrence of rattling is partly due to the connection structure which allows the joint member 03 and the motor rotating shaft 01 to slide relative to each other by the serration 03b. This is also a phenomenon and is considered to be a phenomenon mainly occurring when an excessive torque is input by kickback from the road surface or when the clutch mechanism is actuated, but of course it is not limited to such a phenomenon, and rattling of the joint member 03 is caused. Depending on the degree of progress of contact, the joint member 0
No. 3 moves easily and causes a displacement.

The axial movement of the joint member 03 due to rattling not only makes the slip setting load by the torque limiter 03a unstable, but also the connecting portion by the elastic frictional force of the torque limiter 03a. Early wear and deterioration will be promoted more and more, and problems such as occurrence of abnormal noise by contact with the bearing or the like due to movement of the joint member 03 will sometimes occur, and in any case, the function and damage of the torque limiter 03a will deteriorate. The joint member 03 and the motor rotary shaft 01
Also, the durability of the connecting portion with the worm shaft 02 is significantly reduced. Therefore, from the viewpoint of improving the durability of the joint member 03 and the connecting portion between the shafts 01 and 02, the axial movement of the joint member 03 due to rattling does not pose a problem.

[0011]

SUMMARY OF THE INVENTION The present invention relates to an improvement of an auxiliary steering force transmission mechanism in the electric power steering apparatus for solving the above-mentioned problems, and particularly, in the auxiliary steering force transmission mechanism. The present invention relates to the improvement of the joint member, which is a member that connects the electric motor rotation shaft and the gear shaft of the gear transmission mechanism. The improvement of the joint member is intended to solve the above-mentioned problems. The steering wheel is provided with a joint member for transmitting the steering force to the gear shaft of the gear transmission mechanism and the gear transmission mechanism for transmitting the auxiliary steering force transmitted to the gear shaft to the output shaft of the steering mechanism. In the auxiliary steering force transmission mechanism of the electric power steering device that applies steering to the main steering force by the steering of the The joint member for transmitting a steering force to a gear shaft of the gear transmission mechanism includes a connection between the electric motor rotating shaft, coupling have been made through a torque limiter and serration of the gear shaft of the gear transmission mechanism,
Further, the joint member is provided with means for preventing the axial movement of the joint shaft with respect to the connecting shaft on the torque limiter side.

According to the first aspect of the present invention, the joint member for transmitting the auxiliary steering force from the electric motor rotation shaft to the gear shaft of the gear transmission mechanism is connected to the electric motor rotation shaft and the gear thereof. Since the transmission mechanism is connected to the gear shaft via the torque limiter and the serration, and the joint member is provided with means for preventing its axial movement with respect to the motor rotation shaft, the joint The member is prevented from moving in the axial direction with respect to the connecting shaft on the side where the torque limiter is interposed, rattling of the joint member is suppressed, and a connecting portion by the torque limiter between the joint member and the connecting shaft on the side where the torque limiter is interposed and The joint member and the joint portion can be prevented from being deteriorated due to wear of the joint portion due to the serration with the serration interposing side coupling shaft. Can the significantly improve the durability of the connecting portion between the both axes and.

According to the second aspect of the invention, since the movement preventing means in the axial direction is the C ring, it has a simple structure and can be easily mounted from the outside after the joint member is assembled. The axial movement of the joint member can be reliably prevented.

According to the third aspect of the invention, since the movement preventing means in the axial direction is the elastic ring, it has a simple structure and can be easily mounted at the same time as the joint member is assembled. Axial movement of the joint member can be reliably prevented.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiments of the present invention shown in FIGS. 1 to 3 will be described below.

First, an outline of the electric power steering apparatus 10 of the present invention will be described with reference to FIG.

FIG. 1 shows an electric power steering system 1
0 is a schematic view of the main part of 0, in which the input shaft 11 into which the main steering force is input, the electric motor housing Ha,
The worm gear mechanism housing Hb, the electric motor 4, the hollow shaft 15, the left and right tie rods 14 and the like are shown,
Also shown is the housing 12 of the torque sensor.

As can be seen from FIG. 1, an output shaft (not shown) is connected to the input shaft 11 via a torsion bar, so that a steering wheel (not shown) can be connected to the output shaft. The main steering force of the electric motor 4 is input, and the auxiliary steering force from the electric motor 4 is input.
Is decelerated through the worm gear mechanism 5 and transmitted to one side of the output shaft. The output shaft transmits the steering force to the rack shaft 13 via a pinion gear (not shown) provided on the other side of the left and right tie rods 1.
The wheels 4 and 14 are moved to steer wheels (not shown), and the structure is already well known. In addition, 16 is a dust boot.

FIG. 2 shows a main structural part which is the subject matter of the first embodiment of the present invention. As is clear from the figure, the structural part is covered with a housing, and the housing is electrically driven. It is composed of a housing portion Ha that covers the motor 4 and a housing portion Hb that covers the worm gear mechanism 5, and both housing portions are integrally fixed to each other by bolts 7.

The worm gear mechanism 5 shown on the right side of FIG. 2 has a worm 5a fixed to the worm shaft 2.
And worm wheel 5b fixed to the output shaft of the steering mechanism
The auxiliary steering force from the rotary shaft 1 of the electric motor 4 is decelerated and transmitted to the output shaft by the meshing of the gears 5a and 5b. In addition, 4a and 4b respectively show the rotor and the stator of the electric motor 4.

The worm shaft 2 is rotatable with respect to the housing portion Hb by bearings 2a and 2b at one side (motor side in FIG. 2) position and the other side (counter motor side in FIG. 2) position. The worm shaft 2 is supported, and flange-shaped flange portions 2c, 2c are provided in the vicinity of the support portions of the worm shaft 2 for supporting the bearings 2a, 2b, respectively.
An elastic body 2d such as a rubber spring or a coil spring is interposed between the bearings 2c and 2c and the bearings 2a and 2b, so that a relatively small force transmitted to the worm shaft 2 through the engagement of the worm gear mechanism 5 is achieved. The axial movement of the shaft 2 due to the reaction force is absorbed by the buffering action due to the compression of the elastic body 2d.

One end of the worm shaft 2 is connected to a rotary shaft 1 of an electric motor 4 shown on the left side of FIG. 2 via a joint member 3, and the other end of the shaft 2 is connected to the rotary shaft 1. The ends are supported by bearings 2b.

The connection between the worm shaft 2 and the electric motor rotating shaft 1 via the joint member 3 is made by serrations 3b between the joint member 3 and the worm shaft 2, and the joint member 3 and the worm are connected. Axis 2
Are movable relative to each other in their axial direction and are non-rotatable in their rotational direction. Further, the joint member 3 is connected to the motor rotation shaft 1 by a torque limiter 3a, and the joint member 3 and the motor rotation shaft 1 rotate together as a rotation torque input within a predetermined range to generate power. However, when a rotational torque exceeding a predetermined range is input, relative rotation between the two is allowed and transmission of power is cut off.

By the way, since the connecting portion by the torque limiter 3a is as shown in FIG. 8 described in the prior art, the connecting portion is elastically fatigued under the severe conditions as described above. The elastic member is loosened due to the loss of elastic frictional force due to deformation of the corrugated ridges or the like, causing looseness (mainly radial looseness) of the joint member 3, and the shaft of the joint member 3 caused by the looseness. As described above, the positional deviation caused by the movement in the direction further accelerates the loss of the normal function of the torque limiter 3a.

In order to prevent the occurrence of the above situation, therefore, in the first embodiment, as shown in FIGS. 2 to 3, the joint member 3 and the electric motor rotary shaft 1 are mounted between the joint member 3 and the rotary shaft 1. A ring R1 is used to prevent axial movement of the joint member 3 with respect to the motor rotation shaft 1. The ring R1 is a C-shaped circlip (hereinafter, referred to as "C"). The term "ring" is used.

The mounting of the C ring, which is the ring R1 to be mounted, is, as shown in FIG. 2, a position slightly closer to the motor 4 side than the joint between the joint member 3 and the torque limiter 3a of the motor rotating shaft 1. The groove portion 3G formed in the joint member 3 and the motor rotating shaft 1
The C ring is formed by mounting the C ring over both groove portions of the groove portion 1G formed in the above. The shape structure of the mounted C ring is not necessarily limited, but in the first embodiment, there are two types. The C ring is presented.

First, the C ring shown in FIG.
It is called "C ring A". 2) and an outline of the structure for mounting the same will be described with reference to the drawing.

The C ring A is made of a thin sheet metal having a predetermined thickness and a predetermined elasticity, and as shown in the figure, its planar shape is a substantially C-shape, and is composed of a base A1 and an arm A2. The base portion A1 is slightly wider, the outer shape portion A3 has an arc shape, and the inner shape portion is formed as a straight line portion A4 forming a part of a chord with respect to the arc, and the arm portion A2 is Formed as a pair of members that are narrower in width than the base portion A1 and extend from the both ends of the base portion A1 with a constant width for a predetermined length so as to face each other while drawing an arc across the straight portion A4,
An arcuate portion A5 on the inner side of the arm portion A2 is formed in an arcuate shape substantially corresponding to an annular groove portion 3G3 of the joint member 3 which will be described later, and an arcuate portion A6 on the outer side thereof is the outer contour portion A3 of the base portion.
It is formed as an arc shape that is continuous with the arc.

On the other hand, the groove in which the C ring A is mounted is
The groove portion 3G formed in the joint member 3 is formed as a groove portion having a predetermined width over the entire outer peripheral portion of the joint member 3, and the groove portion 3G has a predetermined width and depth over a half circumference thereof. Annular groove 3G3 having a thickness and the annular groove 3G
Linear groove 3 in which both ends 3G5 of 3 are connected to both ends 3G2
The linear groove portion 3G1 is a linear groove portion cut from the outer peripheral portion of the joint member 3 along the chord direction thereof, and the linear groove portion 3G1 is formed in the mounting hole 3j of the joint member 3 to the motor rotating shaft 1. It is cut to a position that exceeds the forming surface 3k by L.

The groove portion 1G formed on the motor rotating shaft 1 is an annular groove portion having a predetermined width and depth formed over the entire outer peripheral portion of the motor rotating shaft 1, and the annular groove portion 1 is formed.
The depth D of the G is the straight groove portion 3G of the joint member 3.
The depth is equal to or slightly deeper than the depth of cut L that exceeds the mounting hole forming surface 3k of No. 1, and due to the relationship between the depth D of the annular groove 1G and the depth of cut L, when the C ring A is mounted, The base linear portion A4 is the linear groove portion 3G1 of the joint member 3 and the bottom portion 1G of the annular groove portion 1G of the motor rotating shaft 1.
1 or abut with the annular groove 1G.

The groove 3G formed in the joint member 3 and the groove 1G formed in the motor rotating shaft 1 have the same width, and the width is substantially the same as the thickness of the C ring A.

To mount the C ring A, the groove portion 3G of the joint member 3 is aligned with the groove portion 1G of the motor rotating shaft 1 in the axial direction, and the C ring A is attached to the outer periphery of the joint member 3. From the side of the joint member 3 along the groove 3G, and the insertion is performed by C
The base linear portion A4 of the ring A is held so as to be parallel to the linear groove portion 3G1 of the groove portion 3G of the joint member 3, and the base outer peripheral portion A3 is pressed or lightly tapped. The portion A2 is gradually inserted along the annular groove portion 3G3 of the joint member 3, and the inner arcuate portion A5 of the arm portion A2 is made to elastically enter along the bottom portion 3G4 of the annular groove portion 3G3, and by the insertion, the C The base linear portion A4 of the ring A abuts on the linear groove portion 3G1 of the joint member 3 and the groove portion 1G of the motor rotating shaft 1
Is engaged with.

Then, in this state, as shown in FIG. 3a, the C-ring A has inner arcuate portions A5 of both arm portions A2 thereof holding the bottom portion 3G4 of the annular groove portion 3G3 of the joint member 3 from both sides. In this way, the bottom portion 3G4 is elastically locked, and at the same time, the base portion A4 presses the bottom portion 1G1 of the annular groove 1G of the motor rotating shaft 1. The base linear portion A4 does not necessarily have to be pressed and brought into contact with the bottom portion 1G1 of the annular groove 1G.

Therefore, in the mounting completed state shown in FIG. 3a, the base linear portion A4 of the C ring A is entirely in contact with the linear groove portion 3G1 of the joint member 3 and the ring shape of the motor rotary shaft 1 is increased. Since the groove bottom portion 1G1 is pressure-contacted and both the arm portions A2 are pressure-contacted with the annular groove bottom portion 3G4 of the joint member 3 by its elasticity, the C ring A extends across both the joint member 3 and the motor rotation shaft 1. It is held securely by the elastic contact locking force.

The elastic contact locking force of the C-ring A is set to such an extent that the C-ring A does not drop out in a normal use mode and does not affect the function of the torque limiter 3a.

By using the C ring A, the relative movement of both the joint member 3 and the motor rotating shaft 1 in the axial direction is almost completely prevented.

Next, the structure of another C ring (hereinafter referred to as "C ring B") shown in FIG. 3b and its mounting structure will be described.

As shown in FIG. 3b, the C-ring B is made of a thin sheet metal having a predetermined thickness and a predetermined elasticity and has a hairpin-shaped base B1 curved in an arc shape and the base B.
1 is provided with a pair of arm portions B2 facing each other linearly and in parallel for a predetermined length. The pair of arm portions B2 have their tips slightly bent inward. It has an inward locking portion B3 that acts as a locking portion. The distance between the both arm portions B2 is set such that the bottom portion 1G1 of the annular groove portion 1G of the motor rotating shaft 1 is pinched by its elasticity when the C ring B is mounted. Even in this case, it is not always necessary to hold the pressure. The base portion B1 and the arm portion B2 may have the same width or the base portion may have a slightly wider width, and the planar shape thereof is a slightly deformed C-shape.

On the other hand, the structure of the groove portion in which the C ring B is mounted is such that the groove portion 3G of the joint member 3 is a pair of linear groove portions cut along the chord direction from the outer peripheral facing surface of the joint member 3. 3G6, the pair of linear groove portions 3G6 are parallel to each other, and both linear groove portions 3G6
Are connected to each other through an arcuate groove portion 3G7 formed as a relatively shallow outer peripheral groove portion at one end portion thereof, and the other end portions thereof are inclined to each other so as to approach each other.
The groove portion 3G8 reaches the outer peripheral portion without being connected to each other, leaving a part 3m of the outer peripheral portion of the joint member 3. The width of the pair of linear grooves 3G6 is substantially the same as the plate thickness of the C ring B, and the depth of cut is substantially the same as the bottom 1G1 of the annular groove 1G of the motor rotating shaft 1. It is rare.

The groove portion 1G of the motor rotating shaft 1 is
An annular groove 1 cut from the outer periphery of the rotary shaft 1 with a predetermined width and depth
It is formed as G and has the same width as the pair of linear groove portions 3G6 formed in the joint member 3.

The C ring B is mounted by inserting the pair of linear groove portions 3G6 of the joint member 3 between the tips of the pair of arm portions B2 of the C ring B from the arc groove portion 3G7 side of the joint member 3. It is inserted along the straight groove portion 3G6, and the insertion is made by pressing or tapping the curved portion B5 on the outer circumference of the base portion B1 of the C ring B.
The inner side portions B4 of both arms of the ring B are elastically inserted along the parallel straight groove portions 3G6 of the joint member 3 in response to pushing, and are gradually inserted into the annular groove bottom portion 1G1 of the motor rotating shaft 1 by pinching. It

As shown in FIG. 3b, the pair of arm portions B2 of the C ring B, the inward locking portions B3 of the distal end portions, both straight groove portions 3G6 of the joint member 3 and the oblique cutting groove portion 3G at the other end.
The attachment of the C-ring B is completed in the state of being locked by 8.

Therefore, the C-ring B has its inner side portions on both arms in its completed mounting state shown in FIG. 3b.
B4 elastically clamps the annular groove bottom 1G1 of the motor rotating shaft 1 and the pair of linear groove 3 of the joint member 3
G6 is elastically contacted with the entire surface, and further, the inward locking portions B3 at the ends of the both arm portions B2 are elastically locked to the oblique cut groove portion 3G8 at the other end of the joint member 3, respectively. Held in.

The elastic contact locking force is such that the C ring B does not drop out in a normal use state and does not affect the function of the torque limiter 3a.

When the C-ring B is mounted, the displacement due to the axial movement of the joint member 3 is almost completely prevented.

Here, the operation of the present invention will be briefly described with reference to FIGS.

When the driver steers a steering wheel (not shown) while the vehicle is running, a torsion bar (not shown) is twisted according to the steering force, and the input shaft 11
Relative rotation occurs between the output shaft and the output shaft (not shown). The torque sensor detects this relative rotation and issues a signal, and the electric motor 4 is controlled and driven based on the signal. The auxiliary steering force, which is the drive output of the electric motor 4, is transmitted from the rotary shaft 1 of the electric motor 4 to the worm shaft 2 via the joint member 3, and the meshing between the worm 5a and the worm wheel 5b is performed. Is transmitted to the output shaft of the steering mechanism, and is further applied to a tie rod 14 from a pinion gear (not shown) of the output shaft via a rack shaft 13 to give an assisting force for steering wheels (not shown).

A relatively slight reaction force is input to the worm shaft 2 via the worm gear mechanism 5 when the driver reverses the steering direction or inputs vibration from the road surface while the vehicle is traveling. The reaction force causes the worm shaft 2 to move in its axial direction. The axial movement of the worm shaft 2 causes compression of the elastic body 2d via the flange-shaped flange portion 2c provided on the shaft 2. It is absorbed without trouble by the structure capable of axial relative movement by the serration 3b with the joint member 3 associated with the operation.

When a large rotational torque is input to the worm shaft 2 due to kickback from the road surface, which often occurs when the vehicle runs on rough terrain or on rough roads, the rotational torque is transmitted from the worm shaft 2 through the serrations 3b. Although the torque is transmitted to the joint member 3, the torque limiter 3a, which is a connecting portion between the joint member 3 and the motor rotating shaft 1, causes the connecting portion to relatively slide, and the excessive rotational torque is generated by the motor. It is not transmitted to the rotary shaft 1.

By the way, the torque limiter 3a has a structure as shown in FIG. 8 described above, and due to long-term use, the torque limiter 3a is loosened due to a decrease in frictional force due to elastic fatigue. As a result, the joint member is No. 3 causes rattling (mainly rattling in the radial direction), and a position shift occurs due to the axial movement as described above.

However, in the first embodiment of the present invention, even if the torque limiter 3a is loosened as described above, the joint member 3 does not have the ring R1.
The C-ring A or B restricts the movement of the rotary shaft 1 of the motor, so that the backlash of the joint member 3 is suppressed and the positional displacement due to the axial movement thereof is almost completely prevented.

Since the first embodiment shown in FIGS. 1 to 3 is configured as described above, the torque limiter 3a of the joint member 3 loosens due to the elastic fatigue and the decrease in elastic frictional force as described above. Since the C-rings A or B almost completely prevent the joint member 3 from moving in the axial direction, there is no axial displacement of the joint member 3 and rattling is suppressed. Further wear and deterioration of the member 3 and the connecting portion between the joint member 3 and the motor rotating shaft 1 and the worm shaft 2 are prevented, and the generation of abnormal noise due to rattling is eliminated. The durability of the connecting portion between the joint member 3 and the both shafts can be significantly improved.

4 to 5 show a second embodiment of the present invention. The second embodiment is a means for preventing axial movement of the joint member 3 by the C ring A or B which is the ring R1. Instead, an elastic ring r that is a ring R2 is used as the movement preventing means, and the outline of the structure will be described with reference to FIGS.

As is clear from FIG. 5, the elastic ring r is formed as a substantially annular structure having an opening r1 in which the entire outer shape is cut away from a part of the annular structure. The cross-sectional shape of the elastic body such as or resin is circular or elliptical.

On the other hand, the structural portion to which the elastic ring r is attached is the annular groove portion 3G in the mounting hole 3j of the joint member 3 to the motor rotating shaft 1 and the annular groove portion 1G in the outer peripheral portion of the motor rotating shaft 1. is there. The two annular groove portions 3G and 1G have the same axial position when the joint member 3 is assembled to the motor rotating shaft 1, and the connecting portion between the joint member 3 and the motor rotating shaft 1 is the same. Is a groove portion provided at a position closer to the motor 4 side than the position of the torque limiter 3a.

The cross-sectional shape, width, depth, etc. of the annular groove portions 3G, 1G differ depending on the cross-sectional shape and size of the elastic ring r to be mounted, but a semicircular or substantially semicircular shape is common. The two annular groove portions 3G and 1G have the same width, and the depth is slightly shallower in the annular groove portion 3G of the joint member 3 and slightly deeper in the annular groove portion 1G of the motor rotating shaft 1.

To mount the elastic ring r, first, the elastic ring r is fitted into the annular groove portion 1G of the motor rotating shaft 1, and the joint member 3 is fitted into the motor rotating shaft 1 from the shaft end side thereof. The fitting is performed together with the press-fitting via the torque limiter 3a constituent part, and the press-fitting is carried out until the annular groove 3G of the joint member 3 and the annular groove 1G of the motor rotary shaft 1 have the same axial position. During this period, the elastic ring r is reduced in diameter and the motor rotating shaft 1
It is placed in a state where it sinks into the deep annular groove 1G. When the two annular groove portions 3G and 1G have the same axial position, the elastic ring r is released from its reduced diameter state,
Due to its elasticity, the diameter is expanded and fitted into the annular groove portion 3G of the joint portion 3, and the state shown in FIG.
Installation is completed.

Therefore, when the elastic ring r is completely attached, the elastic ring r expands in diameter due to its elasticity and is elastically contacted with the annular groove 3G of the joint member 3, so that the torque limiter 3a becomes loose. Even if it reaches, the backlash of the joint member 3 is suppressed by the elastic contact action of the elastic ring r, and the axial movement thereof is almost completely prevented.

Also in this case, the elastic ring r does not necessarily have to be elastically contacted as long as it engages with the annular groove portion 3G, but when elastically contacted, the elastic ring r itself can be surely prevented from rattling. In addition, the elastic ring r in the completed mounting state
As described above, the elastic contact force due to is adjusted to the extent that it does not affect the function of the torque limiter 3a. Various embodiments can be considered in place of the first and second embodiments.

In the first embodiment shown in FIGS. 1 to 3, the C rings A and B are made of metal thin plates, but instead of this, thin plates of hard resin or the like can be used.

Further, the shapes of the C rings A and B are not necessarily limited to the shapes in the first embodiment, and can be appropriately changed within a range having the function.

In the second embodiment shown in FIGS. 4 to 5, the elastic ring r is made of rubber or resin, but it may be made of metal having a predetermined elasticity.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of an electric power steering apparatus according to the present invention.

FIG. 2 is a diagram showing a main structural portion of an auxiliary steering force transmission mechanism of the electric power steering device according to the present invention.

3 is an enlarged view of a cross-sectional view taken along the line AA in FIG. 2 of the present invention, FIG. 3a shows a usage pattern of one of the C rings, and FIG. .

FIG. 4 is a view showing a main structural portion of an auxiliary steering force transmission mechanism of an electric power steering device according to another embodiment of the present invention.

5 is an enlarged view of the BB cross-sectional view in FIG. 4 of the present invention.

FIG. 6 is a view showing a main structural portion of an auxiliary steering force transmission mechanism of a conventional electric power steering device.

FIG. 7 is an enlarged view showing a structure of a conventional joint portion of a joint portion of a rotary shaft and a worm shaft of an electric motor.

8 is a cross-sectional view taken along the line 0A-0A in FIG. 7, and is a view showing a cross-sectional view of the connecting portion by the torque limiter.

[Explanation of symbols]

1, ... Electric motor rotating shaft, 1a, ... Bearing, 1G,
... Annular groove, 1G1, ... Annular groove bottom, 2, ...
..Worm shafts, 2a, 2b, ... Bearings, 2c, ...
Collar-shaped flange portion, 2d, ... Elastic body, 3, ... Joint member, 3a, ... Torque limiter, 3b, ...
・ Serration, 3j, ... Mounting hole, 3k, ... Mounting hole forming surface, 3G, ... Groove part, 3G1, ... Straight groove part, 3G2, ... Both ends of groove part, 3G3 ... Annular shape Groove,
3G4, ... annular groove bottom, 3G5, groove both ends, 3G6, straight groove, 3G7, ... arc groove,
3G8, ... Bevel groove part, 4, ... Electric motor, 4a, ...
..Rotor, 4b, ... Stator, 5, ... Worm gear mechanism, 5a, ... Worm, 5b, ... Worm wheel, 6, ... Coupler, 7, ... Bolt, 1
0, ... Electric power steering device, 11, ...
Input shaft, 12, ... Torque sensor housing, 13, ...
・ Rack shafts, 14, ... Tie rods, 15, ...
..Hollow shafts, 16, ... Dust boots, A, ...
..C ring, A1, ... Base, A2, ... Arm, A
3, ... Base outer shape part, A4, ... Base straight part, A5
・ ・ ・ Arm inner arcuate part, A6, ・ ・ ・ Arm outer arcuate part, B, ・ ・ ・ C ring, B1, ・ ・ ・ Base part, B2, ・ ・ ・
Arms, B3, ... Inward locking parts, B4, ... Arms inside parts, B5, ... Arc-shaped parts, R1, ... Rings, R2
... Ring, r, ... Elastic ring, r1, ... Elastic ring opening

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor ▲ Hama ▼ Yohei             112 Hagadai, Haga-cho, Haga-gun, Tochigi Prefecture 1 share             In ceremony company Showa four wheel development center (72) Inventor Tsutomu Kato             112 Hagadai, Haga-cho, Haga-gun, Tochigi Prefecture 1 share             In ceremony company Showa four wheel development center (72) Inventor Akira Fujisaki             112 Hagadai, Haga-cho, Haga-gun, Tochigi Prefecture 1 share             In ceremony company Showa four wheel development center F-term (reference) 3D033 CA04

Claims (3)

[Claims] 1. An electric motor rotating shaft for outputting an auxiliary steering force, a joint member for transmitting an auxiliary steering force from the electric motor rotating shaft to a gear shaft of a gear transmission mechanism, and an auxiliary steering transmitted to the gear shaft. And a gear transmission mechanism for transmitting a force to an output shaft of a steering mechanism, whereby an auxiliary steering force of an electric power steering device for steering by applying the auxiliary steering force to a main steering force by steering of a steering wheel. In the transmission mechanism, the joint member that transmits the auxiliary steering force from the electric motor rotation shaft to the gear shaft of the gear transmission mechanism is connected to the electric motor rotation shaft and is connected to the gear shaft of the gear transmission mechanism. Is formed via a torque limiter and serrations, and the joint member is prevented from axial movement with respect to the connecting shaft on the side where the torque limiter is interposed. Assist steering force transmission mechanism of the electric power steering apparatus characterized in that it comprises a. 2. A C-ring mounted between the joint member and the connecting shaft on the side of the torque limiter serves as means for preventing axial movement of the joint member with respect to the connecting shaft on the side of the torque limiter. The auxiliary steering force transmission mechanism of the electric power steering device according to claim 1. 3. A means for preventing axial movement of the joint member with respect to the connecting shaft on the torque limiter interposing side is an elastic ring mounted between the joint member and the connecting shaft on the torque limiter interposing side. The auxiliary steering force transmission mechanism of the electric power steering device according to claim 1.