WO2016047188A1 - Torque transmitting joint and electric power steering device - Google Patents

Abstract

The drive-side transmission section (20) of the output shaft (12a) of an electric motor and the driven-side transmission section (26) of a worm shaft (6a) are joined by means of a joint (16) for transmitting torque, the joint (16) being provided with an elastic member (18) and a coupling (30), and the joint enables torque to be transmitted therebetween. One axial end of the cup-side uneven surface section (31) of the coupling (30) is engaged with a drive-side first uneven surface section (21) of the drive-side transmission section (20) with circumferential gaps therebetween, and the other axial end is joined to a driven-side first uneven surface section (27) of the driven-side transmission section (26) with circumferential gaps therebetween. The elastic member (18) is provided so as to bridge between the axially intermediate section of the cup-side uneven surface section (31) and a drive-side second uneven surface section (22) of the drive-side transmission section (20) so that torque is transmittable therebetween, and to also bridge between the axially intermediate section of the cup-side uneven surface section (31) and a driven-side second uneven surface section (28) of the driven-side transmission section (26) so that torque is transmittable therebetween. As a result, the provided structure can prevent tooth hitting noise from being generated when the rotational direction of the output shaft of the electric motor, which is the drive shaft, is changed.

Description

Torque transmission joint and electric power steering device

The joint for torque transmission according to the present invention is incorporated in various mechanical devices and used for transmitting torque between the drive shaft and the driven shaft. The electric power steering device of the present invention is used as a steering device of an automobile, and reduces the force required for the driver to operate the steering wheel by using an electric motor as an auxiliary power source. It is.

A power steering device is widely used as a device to reduce the force required for the driver to operate the steering wheel when giving a steering angle to the steered wheels (usually the front wheels except for special vehicles such as forklifts) Has been. In addition, an electric power steering apparatus that uses an electric motor as an auxiliary power source in such a power steering apparatus has begun to spread in recent years. Various structures of such an electric power steering apparatus are known, but in any structure, a rotating shaft that is rotated by the operation of the steering wheel and gives a steered angle to the steered wheels as it rotates. Auxiliary power of the electric motor is applied through the speed reducer. In general, a worm reducer is used as the reducer. In the case of an electric power steering device using a worm speed reducer, a worm that is rotationally driven by an electric motor and a worm wheel that rotates together with the rotating shaft are meshed so that auxiliary power of the electric motor can be transmitted to the rotating shaft. To do. However, in the case of a worm reducer, if no measures are taken, an unpleasant noise called a rattling noise is generated when changing the rotation direction of the rotary shaft based on the backlash that exists in the meshing part of the worm and the worm wheel. Sound may be generated.

As a structure for suppressing the occurrence of such rattling noise, conventionally, it has been considered to elastically press the worm toward the worm wheel by an elastic member such as a spring. 16 to 17 show an example of the electric power steering apparatus described in Patent Document 1. FIG. A front end portion of the steering shaft 2 that is rotated in a predetermined direction by the steering wheel 1 is rotatably supported inside the housing 3, and the worm wheel 4 is fixed to this portion. Worm teeth 5 that mesh with the worm wheel 4 are provided in the axially intermediate portion of the worm shaft 6, and both axial ends of the worm 8 that is rotationally driven by the electric motor 7 are a pair of rolling elements such as deep groove ball bearings. It is rotatably supported in the housing 3 by bearings 9a and 9b. Further, a pressing piece 10 is externally fitted to a portion protruding from the rolling bearing 9 a at the tip of the worm shaft 6, and an elastic member such as a coil spring 11 is provided between the pressing piece 10 and the housing 3. The worm teeth 5 provided on the worm shaft 6 are pressed toward the worm wheel 4 by the coil spring 11 via the pressing piece 10. With such a configuration, the backlash between the worm tooth 5 and the worm wheel 4 is suppressed, and the occurrence of rattling noise is suppressed.

In the case of the conventional structure as described above, the occurrence of rattling noise at the meshing portion between the worm tooth 5 and the worm wheel 4 can be suppressed, but the distal end portion of the output shaft 12 of the electric motor 7 and the proximal end of the worm shaft 6. It is not possible to suppress the abnormal noise generated at the joint with the part. This point will be described below. In the case of the illustrated structure, a spline hole 13 is formed at the base end portion of the worm shaft 6 in order to connect the tip end portion of the output shaft 12 of the electric motor 7 and the base end portion of the worm shaft 6 so that torque can be transmitted. The worm shaft 6 is formed so as to open to the base end surface. On the other hand, a spline shaft portion 14 is formed at the distal end portion of the output shaft 12. And the spline shaft part 14 and the spline hole 13 are spline-engaged, and the output shaft 12 and the worm shaft 6 are coupled so as to be able to transmit torque.

If the spline shaft portion 14 and the spline hole 13 are spline-engaged without any circumferential clearance (without backlash), the connecting portion (spline) between the distal end portion of the output shaft 12 and the proximal end portion of the worm shaft 6 No abnormal noise is generated at the engaging portion). However, in the actual case, a backlash exists in the spline engaging portion. In particular, in the case of a structure that suppresses backlash between the worm tooth 5 and the worm wheel 4 by the structure as shown in FIG. 17 described above, the worm shaft 6 needs to be oscillated and displaced. Backlash cannot be eliminated completely, and it is difficult to prevent abnormal noise.

Patent Document 2 has a structure in which the oscillating displacement of the worm shaft can be smoothly performed by connecting the output shaft of the electric motor and the worm shaft via a metal-made cylindrical power transmission member. Are listed. In the case of the invention described in Patent Document 2 as well, in order to swing and displace the worm shaft, spline shaft portions (male splines) provided at both ends of the power transmission member, the worm shaft and the electric motor Backlash exists in each spline engaging portion with a spline hole (female spline) provided at each end of the output shaft. For this reason, when changing the rotation direction of the rotating shaft, there is a possibility that abnormal noise is generated.

Japanese Unexamined Patent Publication No. 2004-306898 Japanese Unexamined Patent Publication No. 2012-131249

In view of the circumstances as described above, an object of the present invention is to realize a structure of a torque transmission joint that can prevent noise from being generated when the rotation direction of a drive shaft is changed.

The torque transmission joint of the present invention and the torque transmission joint of the electric power steering apparatus transmit torque between the ends of the drive shaft and the driven shaft that are arranged in series with respect to the axial direction. Because
A coupling provided with a cup-side uneven portion formed by alternately arranging concave portions and convex portions over the entire circumference on one of the inner and outer peripheral surfaces;
An elastic member made of an elastic material such as an elastomer such as rubber, having driving side clamping pieces provided at a plurality of circumferential positions and driven side clamping pieces provided at a plurality of circumferential directions;
Provided directly or through other members at the end of the drive shaft, and on both the inner and outer peripheral surfaces facing the cup-side uneven portion, the concave portion and the convex portion are alternately arranged over the entire circumference. A drive-side transmission portion provided with a drive-side uneven portion disposed on
Provided directly or via other members at the end of the driven shaft, and on both the inner and outer peripheral surfaces facing the cup-side concavo-convex portion, the concave portion and the convex portion are provided over the entire circumference. And a driven-side transmission portion provided with driven-side uneven portions arranged alternately.
A part in the axial direction of the drive-side uneven portion includes a circumferential gap in the cup-side uneven portion (a convex portion constituting the drive-side uneven portion and a convex portion constituting the cup-side uneven portion. Between the side faces in the circumferential direction with a gap provided between them, and the remaining axial part of the driving side uneven parts has the driving side clamping pieces interposed in the cup side uneven parts. (Each drive side clamping piece is engaged between the circumferential side surfaces of the convex portion constituting the drive side uneven portion and the convex portion constituting the cup side uneven portion).
In addition, a part of the driven-side uneven portion in the axial direction includes a circumferential clearance in the cup-side uneven portion (a convex portion constituting the driven-side uneven portion and a cup-side uneven portion are configured. The circumferential side surfaces of the protrusions are engaged with each other in a state in which a gap is provided), and the remaining axial portion of the driven side uneven portions is sandwiched between the driven side uneven portions by the driven side uneven portions. In a state where a piece is interposed (each driven side clamping piece is sandwiched between circumferential side surfaces of the convex portion constituting the driven side uneven portion and the convex portion constituting the cup side uneven portion) Is engaged.

In the case of implementing the torque transmission joint of the present invention as described above, the driving side uneven portion (driven side uneven portion) is provided on a member fixed to the end portion of the driving shaft (driven shaft). In this case, the member is made of a material that is less likely to be elastically deformed (has higher rigidity) than the elastic material constituting the elastic member, such as a metal material such as a synthetic resin or a sintered metal, and the member is connected to the drive shaft. It is an interference fit to the end of the (driven shaft) or a female spline portion (including fine serrations on the pitch) formed on one inner peripheral surface of these members and the driving shaft (driven shaft). A male spline formed on the other outer peripheral surface is press-fitted and fitted into the spline, for example, to support it while preventing relative rotation and relative displacement in the axial direction.

Preferably, when implementing the torque transmission joint of the present invention as described above, the circumferential dimension (thickness in the circumferential direction) of each driving side clamping piece is a part of the driving side uneven part in the axial direction. And a gap in the circumferential direction between the concavo-convex portion on the cup side (a distance between the convex portions constituting the drive-side concavo-convex portion and the circumferential side surfaces of the convex portions constituting the cup-side concavo-convex portion facing each other). At the same time, the circumferential dimension of each driven-side clamping piece is made larger than the circumferential gap between a part of the driven-side uneven portion in the axial direction and the cup-side uneven portion.

When the present invention as described above is carried out, specifically, for example, the driving side uneven portion is formed on one half of the axial direction (half on the side far from the driven shaft). It is comprised from a 1st uneven | corrugated | grooved part and the drive side 2nd uneven | corrugated | grooved part formed in the other half part (similar half part of an axial direction). Of these, the driving-side first uneven portion is engaged with one end in the axial direction of the cup-side uneven portion with a circumferential gap interposed therebetween, and the driving-side second uneven portion is connected to the cup-side uneven portion. Engage in a state where each driving side clamping piece is interposed in a portion near one end in the axial direction (a portion near the driving shaft in the intermediate portion in the axial direction). Further, the driven side uneven portion is formed on the other half portion in the axial direction (half portion on the side far from the driving shaft) and the first uneven portion on the driven side (same side on the same side). Of the driven side second concavo-convex part formed in the half part. Of these, the driven-side first uneven portion is engaged with the other end portion in the axial direction of the cup-side uneven portion with a circumferential gap interposed therebetween, and the driven-side second uneven portion is The cup-side concavo-convex portion is engaged with a portion closer to the other end in the axial direction (a portion closer to the driven shaft in the intermediate portion in the axial direction) with each driven-side clamping piece interposed therebetween.

In the case of carrying out such an invention, preferably, the elastic member is connected to each driving side holding piece and each driven side holding piece by a disk-shaped or ring-shaped connecting plate part, The whole is formed integrally.
Preferably, at least one end of the coupling in the axial direction, both opposite circumferential side surfaces of the convex portions constituting the cup-side concavo-convex portion are used as end edges of the coupling. Inclined in the direction away from each other as it goes.
Further preferably, each of the driving side clamping pieces is disposed adjacent to the driving side first uneven portion in the axial direction, and each of the driven side holding pieces is connected to the driven side first uneven portion. It is arranged adjacent to the axial direction.

Alternatively, when carrying out the present invention as described above, specifically, the cup-side uneven portion is formed on the one axial end portion (the end portion on the drive shaft side), and the cup-side first uneven portion, It comprises a cup-side second uneven portion formed at the other end in the axial direction (end on the driven shaft side) and a cup-side third uneven portion formed at the intermediate portion in the axial direction. Of these, the cup-side first concavo-convex portion engages with the drive-side nip portion interposed between the axial-side end portion and the intermediate portion of the drive-side concavo-convex portion. In addition, the cup-side second uneven portion engages with the other end in the axial direction or the intermediate portion of the driven-side uneven portion with the driven-side clamping piece interposed therebetween. In addition, one end of the cup side third uneven portion is engaged with the other end in the axial direction of the drive side uneven portion with a circumferential gap interposed therebetween, and the cup side third uneven portion The other end in the axial direction engages with one end in the axial direction of the driven-side concavo-convex portion with a circumferential clearance interposed therebetween.
In the case of carrying out such an invention, preferably, the elastic member is a driving side elastic body provided with the driving side clamping pieces, and the driven side elastic body provided separately from the driving side elastic body. It is comprised from the to-be-driven elastic body provided with a clamping piece.
Preferably, at least one of the axial ends of the cup-side third concavo-convex portion, the opposite circumferential side surfaces of the convex portions constituting the cup-side third concavo-convex portion are As it goes to the edge of the cup-side third concavo-convex portion, it is inclined in a direction away from each other.
Further preferably, in the driving side elastic body, the driving side clamping pieces are provided at a plurality of circumferential positions on an axial side surface of the annular connecting plate portion, and in the driven side elastic body, the driven side elastic bodies Side clamping pieces are provided at a plurality of locations in the circumferential direction on the side surface in the axial direction of the annular connecting plate portion. The connecting plate portion of the driving side elastic body is disposed between the axial side surface of the driving side transmission portion and one axial end surface of the coupling, and the connecting plate portion of the driven side elastic body is: It arrange | positions between the axial direction side surface of the said driven side transmission part, and the axial direction other end surface of the said coupling.

The electric power steering apparatus of the present invention is
A housing that is supported by a fixed part and does not rotate;
A steering rotation shaft that is rotatably provided with respect to the housing, is rotated by an operation of a steering wheel, and gives a steering angle to the steered wheels in accordance with the rotation;
A worm wheel that is supported concentrically with the steering rotary shaft and rotates together with the steering rotary shaft inside a part of the steering rotary shaft inside the housing;
A worm tooth is provided at an axial intermediate portion of the worm shaft, and both end portions in the axial direction of the worm shaft are rotatably supported by the bearings by bearings in a state where the worm tooth is engaged with the worm wheel. Warm and
An electric motor for rotationally driving the worm;
The output shaft of the electric motor and the worm shaft are connected to each other by a torque transmission joint so that torque can be transmitted.
In particular, in the electric power steering apparatus of the present invention, the torque transmission joint is the above-described torque transmission joint of the present invention. In this case, the output shaft of the electric motor corresponds to the drive shaft, and the worm shaft corresponds to the driven shaft.
When implementing the electric power steering apparatus of the present invention as described above, the tip of the worm shaft (the end opposite to the side coupled to the output shaft of the electric motor via the torque transmission joint) is preferable. A preload applying mechanism that elastically presses the worm toward the worm wheel.

According to the torque transmission joint and the electric power steering apparatus of the present invention as described above, it is possible to prevent the generation of abnormal noise when changing the rotation direction of the drive shaft.
That is, in the case of the present invention, the drive-side uneven portion and the driven-side uneven portion are engaged with each other in the axial direction with a circumferential clearance interposed between the cup-side uneven portion and the drive-side uneven portion. And the driven side concavo-convex part with the driving side nip part and the driven side nip part constituting an elastic member made of an elastic material such as rubber, etc. interposed between the cup side concavo-convex part and the cup side uneven part. Is engaged. Therefore, in the case of the present invention, when the torque transmitted between the drive shaft and the driven shaft is relatively small, the rotational torque of the drive shaft is transmitted to the driven shaft via the elastic member.

On the other hand, when the torque transmitted between the drive shaft and the driven shaft increases, each driving-side clamping piece and each driven-side clamping piece are elastically deformed in the circumferential direction (elastically pressed). Crushed). Then, the circumferential side surface of the convex portion constituting a part in the axial direction of the driving side uneven portion of the drive shaft and the circumferential side surface of the convex portion constituting the cup side uneven portion of the coupling directly abut (contact). In addition, the circumferential side surface of the convex portion constituting the cup side uneven portion and the circumferential side surface of the convex portion constituting a part of the driven side uneven portion of the driven shaft are in direct contact (abutting). ) Since the momentum of these collisions is weakened by the elastic member, it is possible to prevent the generation of unusual noises such as harsh rattling noises at the abutting portions between the concave and convex portions due to the collision. In this state, most of the rotational torque of the drive shaft is transmitted to the coupling by the engagement of a part of the drive side uneven portion in the axial direction and the cup side uneven portion, and most of the torque transmitted to the coupling. Is transmitted to the driven shaft by the engaging portion between the cup-side uneven portion and the driven-side uneven portion in the axial direction. Thus, according to the present invention, the torque transmission characteristics between the drive shaft and the driven shaft can be divided into at least two stages according to the magnitude of the torque to be transmitted.

The partial cutaway side view showing a 1st embodiment of the present invention. The II section enlarged view of FIG. Enlarged view of the right part of Fig. 2 4A is a cross-sectional view taken along line IV-IV in FIG. 3, and FIG. 4B is a cross-sectional view taken along line IV′-IV ′ in FIG. (A) is an end view showing a drive-side transmission member taken out, and (B) is a VV cross-sectional view of (A). (A) is an end view showing the driven transmission member taken out, (B) is a sectional view taken along the line VI-VI of (A). (A) is an end view showing the coupling taken out, (B) is a sectional view taken along the line VII-VII of (A), and (C) is a view taken along the arrow VII ′ of (A). (A) is an end view showing an elastic member taken out, (B) is a sectional view taken along line VIII-VIII of (A). The figure similar to FIG. 3 which shows 2nd Embodiment of this invention. (A) is a sectional view showing a joint for torque transmission, (B) is a sectional view taken along line XX in (A), and (C) is a sectional view taken along line X′-X ′ in (A). (A) is an end view showing a drive-side transmission member taken out, and (B) is a sectional view taken along line XI-XI in (A). (A) is an end view showing a driven transmission member taken out, and (B) is a sectional view taken along line XII-XII in (A). (A) is an end view showing the coupling taken out, (B) is a cross-sectional view taken along line XIII-XIII in (A). (A) is an end view showing an elastic body taken out, and (B) is a sectional view taken along the line XIV-XIV in (A). The figure similar to FIG. 3 which shows the modification of embodiment of this invention. The partial longitudinal section side view showing an example of the steering device for cars. FIG. 17 is an enlarged XVII-XVII sectional view of FIG. 16 showing an example of a conventional structure of an electric power steering device.

[First Embodiment]
1 to 8 show a first embodiment of the present invention. In addition, the features of the present invention, including the present embodiment, realize a structure that can prevent the occurrence of abnormal noise such as rattling noise when changing the rotation direction of the output shaft of the electric motor that is the drive shaft. In the point. In the electric power steering apparatus according to the present embodiment, the front end portion of the steering shaft 2 that is rotated in a predetermined direction by the steering wheel 1 is rotated inside the housing 3 in the same manner as the conventional structure shown in FIGS. The worm wheel 4 is fixed to this portion. The worm teeth 5 that mesh with the worm wheel 4 are provided at an intermediate portion in the axial direction of the worm shaft 6a. Both ends in the axial direction of the worm 8 that is rotationally driven by the electric motor 7 are rotatably supported in the housing 3 by a pair of rolling bearings 9a and 9b. Further, a preload applying mechanism 15 is provided between the rolling bearing 9a fitted on the tip of the worm shaft 6a and the housing 3, and the worm teeth 5 provided on the worm shaft 6a are pressed against the worm wheel 4. is doing. With such a configuration, the backlash between the worm tooth 5 and the worm wheel 4 is suppressed, and the occurrence of rattling noise is suppressed.

In the case of the present embodiment, the distal end portion of the output shaft 12a of the electric motor 7 and the proximal end portion of the worm shaft 6a are coupled via a torque transmission joint 16 so as to be able to transmit torque. The torque transmission joint 16 includes a driving side transmission unit 20, a driven side transmission unit 26, a coupling 30, and an elastic member 18.

The drive-side transmission unit 20 is provided with a drive-side transmission member 19 that is provided separately from the output shaft main body 17 of the output shaft 12a, at the distal end portion of the output shaft main body 17, by relative rotation and relative rotation in the axial direction. In a state in which the torque is blocked (to allow transmission of torque), it is provided at the distal end of the output shaft 12a. Alternatively, the drive-side transmission unit 20 replaces a female spline (including fine serrations) formed on the inner peripheral surface of the drive-side transmission member 19 with a male spline unit formed at the tip of the output shaft body 17. By press-fitting, spline fitting is performed in a state where relative rotation and relative displacement in the axial direction are prevented. The drive-side transmission member 19 is made of a material such as a synthetic resin or a sintered metal that is less likely to be elastically deformed (has higher rigidity) than an elastic material such as an elastomer such as rubber that constitutes the elastic member 18.

As shown in FIG. 5, on the outer peripheral surface of the drive-side transmission member 19, there is provided a drive-side concavo-convex portion 39 in which concave portions and convex portions are alternately arranged over the entire circumference. In the case of the present embodiment, the drive-side uneven portion 39 is a drive-side first uneven portion provided in an axial half portion (the right half portion in FIGS. 1 to 3) that is a half portion far from the worm shaft 6a. And a drive-side second uneven portion 22 provided in the other half portion in the axial direction (the left half portion in FIGS. 1 to 3), which is also a half portion on the near side. And the space | interval (circumferential width dimension) of the circumferential direction side surfaces where the convex part which comprises the drive side 2nd uneven | corrugated part 22 mutually opposes is the circumferential direction which the convex part which comprises the drive side 1st uneven part 21 mutually opposes. While making it larger than the space | interval of side surfaces, the outer diameter size of the bottom face of the recessed part which comprises the drive side 2nd uneven | corrugated | grooved part 22 is made smaller than the outer diameter dimension of the bottom face of the recessed part which comprises the drive side 1st uneven | corrugated part 21. ing. Further, a driving side flange 23 is provided on the outer peripheral surface of one end portion (right end portion in FIGS. 1 to 3) of the driving side transmission member 19 over the entire circumference, and the driving side first uneven portion 21 ( The opening on one side in the axial direction of the recessed portion) is closed.

The driven-side transmission portion 26 is configured such that the driven-side transmission member 25 provided separately from the worm shaft main body 24 of the worm shaft 6a is fitted into the base end portion of the worm shaft main body 24, or is fitted with a spline. For example, it is provided at the base end portion of the worm shaft 6a by being fitted and fixed in a state where relative rotation and relative displacement in the axial direction are prevented. The driven-side transmission member 25 is made of a material that is less likely to be elastically deformed than the elastic material constituting the elastic member 18.

As shown in FIG. 6, on the outer peripheral surface of the driven-side transmission member 25, a driven-side concavo-convex portion 40 is provided, in which concave portions and convex portions are alternately arranged over the entire circumference. In the case of this embodiment, the driven-side uneven portion 40 is on the same side as the driven-side first uneven portion 27 provided on the other half portion in the axial direction, which is a half portion far from the output shaft 12a. It is comprised from the driven side 2nd uneven | corrugated | grooved part 28 provided in the axial direction piece half part which is a half part. And the space | interval of the circumferential direction side surfaces which the convex part which comprises the to-be-driven side 2nd uneven | corrugated part 28 mutually opposes, The space | interval of the circumferential direction side surfaces to which the convex part which comprises the to-be-driven side 1st uneven | corrugated part 27 mutually opposes. And the outer diameter of the bottom surface of the concave portion constituting the driven-side second uneven portion 28 is made smaller than the outer diameter size of the bottom surface of the concave portion constituting the driven-side first uneven portion 27. . In addition, on the outer peripheral surface of the other end in the axial direction of the driven-side transmission member 25, a driven-side flange 29 is provided over the entire circumference, and the driven-side first uneven portion 27 (a concave portion constituting the driven-side first concave-convex portion 27). The opening on the other side in the axial direction is blocked. A female spline groove is formed on the inner peripheral surface of the driven transmission member 25.

Further, as shown in FIG. 7, the coupling 30 is formed in a cylindrical shape as a whole, and is configured such that concave portions and convex portions are alternately arranged over the entire circumference on the inner circumferential surface. A cup side uneven portion 31 is provided. One end in the axial direction of the cup-side concavo-convex portion 31 has a drive-side first concavo-convex portion 21 of the drive-side concavo-convex portion 39 with a circumferential gap (backlash) interposed therebetween. The protrusions are engaged in a state where a gap t is provided between the circumferential side surfaces of the protrusions and the protrusions constituting the cup-side uneven portion 31 (see FIG. 4A). The other end in the axial direction of the cup-side concavo-convex portion 31 has a circumferential gap in the driven-side first concavo-convex portion 27 of the driven-side concavo-convex portion 40 (constitutes the driven-side first concavo-convex portion 27. The protrusions are engaged with each other in a state in which a gap is provided between the circumferential side surfaces of the protrusions and the protrusions constituting the cup-side uneven portion 31. The circumferential gap between the cup-side uneven portion 31 and the driving-side first uneven portion 21 and the circumferential gap between the cup-side uneven portion 31 and the driven-side first uneven portion 27 are: Each can be set to any size (can be equal to each other or different).

Further, in the case of the present embodiment, as shown in FIG. 7C, the cup-side uneven portion of the cup-side uneven portion 31 is an end portion in the axial direction that is an engaging portion with the driving-side first uneven portion 21. The opposite circumferential side surfaces of the convex portions 32 and 32 constituting the portion 31 are inclined so as to be separated from each other toward the one axial side (the width dimension between the two circumferential side surfaces is set to one axial side. To be larger) On the other hand, the circumferential opposite side surfaces of the convex portions constituting the drive-side first concave / convex portion 21 that engages with the cup-side concave / convex portion 31 are flat surfaces having a constant rolling interval in the axial direction. Coupling 30 is less likely to be elastically deformed (high rigidity) than elastomers such as rubber, synthetic resin such as polyacetal resin and polyamide resin, or light alloy such as iron-based metal such as carbon steel, aluminum-based alloy, etc. Made of material. Such a coupling 30 is assembled between the drive-side transmission portion 20 and the driven-side transmission portion 26, and the inner side surfaces of the drive-side flange portion 23 and the driven-side flange portion 29 that face each other. Is sandwiched between.

Further, as shown in FIG. 8, the elastic member 18 is integrally formed as a whole by an elastic material such as an elastomer such as rubber, and the circumference of the outer peripheral surface of the disk-shaped connecting plate portion 33 extending in the radial direction. Engagement pieces 34 and 34 having a concave (U-shaped) end surface shape (the outer peripheral surface is recessed inward in the radial direction) are supported at a plurality of locations in the direction. And while providing the outer diameter side uneven | corrugated | grooved part 35 in the outer peripheral surface of the elastic member 18, the inner diameter side uneven | corrugated | grooved part 36 is provided in the part which remove | deviated from the connection board part 33 to the axial direction among the inner peripheral surfaces. That is, the outer diameter side uneven portion 35 has a recessed portion as a portion recessed inward in the radial direction of the outer peripheral surface of each engagement piece 34, 34, and a circumferential wall portion 37 of the adjacent engagement pieces 34, 34. , 37 (a portion including a pair of circumferential wall portions 37, 37) between the inner side surfaces is configured as a convex portion. On the other hand, in the inner diameter side uneven portion 36, a portion between adjacent engagement pieces 34, 34 is a concave portion, and an inner diameter side portion of each engagement piece 34, 34 is a convex portion.

Further, as shown in FIG. 4, in the case of the present embodiment, the circumferential direction dimension T ₃₇ of each circumferential wall portion ₃₇ , ₃₇ is set in the circumferential direction between the cup side uneven portion 31 and the drive side first uneven portion 21. The clearance t is larger than the circumferential clearance between the cup-side uneven portion 31 and the driven-side first uneven portion 27 (T ₃₇ > t). The elastic member 18 engages the outer diameter-side uneven portion 35 with the axially intermediate portion of the cup-side uneven portion 31 of the coupling 30 without any gap, and the axial end portion of the inner-diameter uneven portion 36 is connected to the drive side first. The other concavo-convex portion 22 is engaged with the other end portion in the axial direction on the driven-side second concavo-convex portion 28 without any gap. In other words, the driving-side second uneven portion 22 and the driven-side second uneven portion 28 are engaged with the cup-side uneven portion 31 with the circumferential wall portions 37 and 37 interposed therebetween. Thereby, the axial direction half half of each circumferential direction wall part 37 and 37 is arrange | positioned adjacent to the drive side 1st uneven | corrugated | grooved part 21 of the drive side transmission member 19, and each circumferential direction wall. The other half portion in the axial direction of the portions 37 and 37 is disposed adjacent to the driven-side first uneven portion 27 of the driven-side transmission member 25 in the axial direction.

In addition, between the outer diameter side uneven part 35 and the cup side uneven part 31, and between the inner diameter side uneven part 36, the driving side second uneven part 22, and the driven side second uneven part 28, respectively in the circumferential direction. It is also possible to provide a gap. In this case, the circumferential clearance between the outer diameter side uneven portion 35 and the cup side uneven portion 31, and the inner diameter side uneven portion 36 and the driving side second uneven portion 22 (driven side second uneven portion 28), The gap in the circumferential direction is made smaller than the gap in the circumferential direction between the cup-side uneven portion 31 and the driving-side first uneven portion 21 (driven-side first uneven portion 27). In any case, in the case of this embodiment, the outer diameter side uneven portion 35 is engaged with the cup side uneven portion 31 and the inner diameter side uneven portion 36 is connected to the driving side second uneven portion 22 and the driven side second uneven portion. By engaging with the concavo-convex portion 28, the axial half of each of the circumferential wall portions 37, 37 is formed on the cup side and the convex portion constituting the drive-side concavo-convex portion 39 (drive-side second concavo-convex portion 22). While sandwiching between the circumferential side surfaces of the convex portion constituting the concave and convex portion 31, the other half portion in the axial direction is also the convex portion constituting the driven side concave and convex portion 40 (driven side second concave and convex portion 28). And the side surfaces in the circumferential direction of the convex portions constituting the cup-side uneven portion 31 are sandwiched. That is, in the case of this embodiment, the axial half piece of each of the circumferential wall portions 37, 37 corresponds to the driving side clamping piece of the present invention, and the other axial half portion of the circumferential wall portion 37, 37 is the same as that of the present invention. It corresponds to the driven side clamping piece. In addition, as shown by a chain line in FIG. 8A, a through hole 38 or a thin wall portion (not shown) is provided in the central portion of the connecting plate portion 33 to reduce the material constituting the elastic member 18. it can.

In the case of the electric power steering apparatus of the present embodiment as described above, the driving-side first uneven portion 21 and the driven-side first uneven portion 27 are in a state where a circumferential clearance is interposed in the cup-side uneven portion 31. Thus, the driving side second uneven portion 22 and the driven side second uneven portion 28 interpose the circumferential wall portions 37 and 37 constituting the elastic member 18 in the cup side uneven portion 31, respectively. Are engaged with each other. And the circumferential direction dimension of each circumferential direction wall part 37 and 37 is the circumferential direction clearance gap between the cup side uneven part 31 and the drive side 1st uneven part 21, and the cup side uneven part 31 and the driven side 1st. It is larger than the circumferential clearance between the concave and convex portions 27. Therefore, in the case of the present embodiment, when the torque transmitted between the output shaft 12a of the electric motor 7 and the worm shaft 6a is relatively small, the rotational torque of the output shaft 12a is the drive side second uneven portion 22. Is transmitted to the elastic member 18 from the engagement portion between the inner and outer side uneven portions 36. The torque transmitted to the elastic member 18 is transmitted to the worm shaft 6a from the engagement portion between the inner diameter side uneven portion 36 and the driven side second uneven portion 28.

On the other hand, when the torque transmitted between the output shaft 12a and the worm shaft 6a increases, the elastic member 18 is elastically deformed in the circumferential direction. That is, the circumferential wall portions 37 and 37 constituting the engagement pieces 34 and 34 of the elastic member 18 are elastically crushed in the circumferential direction (the circumferential width dimension is reduced). And the circumferential direction side surface of the convex part which comprises the cup side uneven | corrugated | grooved part 31, the circumferential direction side surface of the convex part which comprises the drive side 1st uneven | corrugated part 21, and the convex part which comprises the to-be-driven side 1st uneven part 27 Directly contact (contact) each other. Since the momentum of these collisions is weakened by the elastic deformation of the elastic member 18, the abutting portion between the driving-side first uneven portion 21 and the cup-side uneven portion 31, and the cup side are accompanied by the collision. It is possible to prevent the generation of unusual noise such as an unpleasant rattling sound at the contact portion between the uneven portion 31 and the driven-side first uneven portion 27. In this state, most of the rotational torque of the output shaft 12 a is transmitted to the coupling 30 from the engagement portion between the drive side first uneven portion 21 and the cup side uneven portion 31, and is transmitted to the coupling 30. Most of the torque is transmitted to the worm shaft 6a from the engaging portion between the cup-side uneven portion 31 and the driven-side first uneven portion 27.

As described above, according to the electric power steering apparatus of this embodiment, the torque transmission joint 16 is formed by combining the elastic member 18 and the coupling 30 for torque transmission between the output shaft 12a and the worm shaft 6a. Thus, the torque transmission characteristic can be divided into two stages according to the magnitude of the torque to be transmitted, and the operational feeling of the steering wheel 1 (see FIG. 16) can be improved. That is, generally, in the electric power steering apparatus, when a vibration load is applied to the steering shaft 2 from the wheel side due to, for example, a rough road surface, torque is applied to the worm wheel 4 fixed to the steering shaft 2. When the torque sensor detects the torque, a controller (not shown) causes the electric motor 7 to generate a torque in a direction to cancel the torque. Thereby, the operational feeling of the steering wheel 1 can be improved. Here, the worm shaft 6a having the worm teeth 5 meshing with the worm wheel 4 tends to rotate due to the reaction force of the torque applied to the worm wheel 4, but the worm shaft 6a and the output shaft 12a of the electric motor 7 are relatively When the resistance to rotation (torsional rigidity) is high, the resistance to rotation of the worm shaft 6a increases. Since the torque applied to the worm wheel 4 based on the vibration load applied to the steering shaft 2 is relatively small, the operational feeling of the steering wheel 1 may be impaired if the rotational resistance of the worm shaft 6a is large. In the case of this embodiment, when torque transmission between the output shaft 12a and the worm shaft 6a is performed via the torque transmission joint 16, the transmission torque between the output shaft 12a and the worm shaft 6a is small. Since the torsional rigidity can be lowered and the torsional rigidity can be increased when the transmission torque is large, the operational feeling of the steering wheel 1 can be improved.

Note that the circumferential clearance between the cup-side uneven portion 31 and the driving-side first uneven portion 21 and the circumferential clearance between the cup-side uneven portion 31 and the driven-side first uneven portion 27 are mutually equal. Or different between the outer diameter side uneven portion 35 and the cup side uneven portion 31, and between the inner diameter side uneven portion 36, the driving side second uneven portion 22 and the driven side second uneven portion 28, respectively. By providing a circumferential clearance, the torque transmission characteristics between the output shaft 12a and the worm shaft 6a can be increased more than two stages.

In the case of the present embodiment, the coupling 30 can also be connected to the worm shaft 6a when the worm shaft 6a is displaced by oscillating or the center axis of the worm shaft 6a and the center axis of the output shaft 12a are not aligned. By tilting with respect to the central axis of the shaft 6a and the central axis of the output shaft 12a, torque transmission between the output shaft 12a and the worm shaft 6a can be performed smoothly. In particular, in the case of this embodiment, the one axial end portions of the opposite circumferential side surfaces of the convex portions 32, 32 constituting the cup-side concavo-convex portion 31 are inclined toward each other toward the one axial side. Therefore, even when the coupling 30 is tilted with respect to the center axis of the output shaft 12a, the cup-side uneven portion 31 and the drive-side first uneven portion 21 can be prevented from coming into contact with each other (biased). The circumferential side surfaces of the convex portions constituting the side uneven portion 31 and the driving side first uneven portion 21 can be brought into surface contact with each other). Therefore, the torque transmission joint 16, extending the stress concentration at the engaging portion between the cup-side uneven portion 31 and the drive-side first uneven portion 21, or the occurrence of wear, The durability of the entire electric power steering device can be secured.

In the case of the present embodiment, the drive side second uneven portion 22 (driven side second portion) that engages with the inner diameter side uneven portion 36 of the elastic member 18 in the drive side transmission portion 20 (driven side transmission portion 26). The circumferential width dimension of the convex portion of the concave-convex portion 28) is made larger than the circumferential width dimension of the convex portion of the driving-side first concave-convex portion 21 (driven-side first concave-convex portion 27), and the driving-side second concave-convex portion The outer diameter of the bottom surface of the concave portion constituting the portion 22 (driven side second uneven portion 28) is larger than the outer diameter of the bottom surface of the concave portion constituting the driving side first uneven portion 21 (driven side first uneven portion 27). Is also small. For this reason, the volume of the elastic member 18 can be ensured, and the strength and durability of the elastic member 18 can be sufficiently ensured.

In the case of the present embodiment, the output shaft 12a is sandwiched between the driving side flange 23 of the driving side transmission unit 20 and the driven side flange 29 of the driven side transmission unit 26. The distance between the distal end surface of the worm shaft and the proximal end surface of the worm shaft 6a is regulated. For this reason, it is possible to prevent the elastic member 18 from being strongly clamped (crushed) in the axial direction between the distal end surface of the output shaft 12a and the proximal end surface of the worm shaft 6a.
The elastic member 18 may be provided in the axial direction via a clearance with the driving-side transmission member 19 and the driven-side transmission member 25, or the axial direction by the driving-side transmission member 19 and the driven-side transmission member 25. May be compressed.

When carrying out the present invention, the drive side transmission part 20 (driven side transmission part 26) does not go through the drive side transmission member 19 (driven side transmission member 25), but the tip part of the output shaft of the electric motor ( You may form directly in the base end part of a worm shaft. In addition, a drive-side concavo-convex portion is formed on the inner peripheral surface of the concave portion provided at the distal end portion of the output shaft of the electric motor, and a driven-side concavo-convex portion is formed on the inner peripheral surface of the concave portion provided at the base end portion of the worm shaft. And it can also comprise so that the coupling side uneven part provided in the outer peripheral surface of the coupling may be engaged with a drive side uneven part and a driven side uneven part.

[Second Embodiment]
9 to 14 show a second embodiment of the present invention. The torque transmission joint 16a of the present embodiment includes a drive side transmission portion 20a, a driven side transmission portion 26a, a coupling 30a, and an elastic member 18a.

The drive-side transmission portion 20a is configured such that the drive-side transmission member 19a provided separately from the output shaft main body 17 is tightened or spline-fitted at the distal end portion of the output shaft main body 17 of the output shaft 12a. It is provided by supporting in a state in which rotation in synchronization with the output shaft 12a is possible and axial displacement with respect to the output shaft 12a is prevented. As shown in FIG. 11, a drive-side uneven portion 39 a is formed on the outer peripheral surface of the drive-side transmission member 19 a, and in the case of this embodiment, the shape of the drive-side uneven portion 39 a (the circumferential width dimension of the protrusion and the recess) The outer diameter dimension of the bottom surface is constant over the axial direction. However, the circumferential width dimension of the convex portion constituting the drive-side uneven portion 39a may be configured to become smaller toward the other side in the axial direction (the tip side of the drive-side uneven portion 39a, the left side in FIG. 8). (You may incline in the direction which mutually separates the circumferential direction both sides | surfaces which each convex part mutually opposes toward an axial direction other side). A drive side flange 23a is provided over the entire circumference on the outer peripheral surface of one end of the drive side transmission member 19a in the axial direction.

The driven-side transmission portion 26a is an interference fit or spline fitting of a driven-side transmission member 25a provided separately from the worm shaft main body 24 at the base end portion of the worm shaft main body 24 of the worm shaft 6a. For example, it is possible to rotate in synchronization with the worm shaft 6a and to support the worm shaft 6a in a state in which axial displacement with respect to the worm shaft 6a is prevented. As shown in FIG. 12, a driven-side uneven portion 40a is formed on the outer peripheral surface of the driven-side transmission member 25a. On the outer peripheral surface of the other end in the axial direction of the driven side transmission member 25a, a driven side flange 29a is provided over the entire circumference. In the present embodiment, the shape of the driven side uneven portion 40a is the same as the shape of the drive side uneven portion 39a. However, the shape of the driven side uneven portion 40a and the shape of the drive side uneven portion 39a can be different from each other.

As shown in FIG. 13, the coupling 30 a has a cup-side first uneven portion 41 at one end in the axial direction and a cup-side second uneven portion 42 at the other end in the axial direction. The cup side third uneven part 43 is provided in each part. That is, the coupling 30a forms the cup-side third uneven portion 43 at the axially intermediate portion of the inner peripheral surface of the cylindrical portion 44 that is formed in a cylindrical shape as a whole, and the circumferential direction of both axial ends of the cylindrical portion 44 Projecting portions 45 and 45, which form the cup-side first uneven portion 41 (cup-side second uneven portion 42) and have a sector shape when viewed from the axial direction, are projected in the axial direction at a plurality of equally spaced locations. Each is provided.

The cup side 1st uneven part 41 (cup side 2nd uneven part 42) makes each protrusion part 45,45 a convex part, and comprises the part between each protrusion part 45,45 adjacent to the circumferential direction as a recessed part. . On the other hand, the cup side 3rd uneven | corrugated | grooved part 43 comprises the convex part 32a and the recessed part alternately arrange | positioned in the circumferential direction. In such a state that the cup-side third uneven portion 43 of such a coupling 30a has a circumferential gap interposed between the other axial end portion of the drive-side uneven portion 39a and the one axial end portion of the driven-side uneven portion 40a. , Respectively. That is, the circumferential dimension d ₄₃ of the axially intermediate portion of the concave portion constituting the cup side third uneven part 43 (the circumferential dimension is smallest becomes part of the recess) is convex portion constituting the driving-side uneven portion 39a It is larger than any of the circumferential dimension d _39a and the circumferential dimension d _40a of the convex portion constituting the driven side uneven portion 40a (d ₄₃ > d _39a = d _40a ). In the case of the present embodiment, the circumferentially opposite side surfaces of the convex portions 32a and 32a constituting the cup-side third uneven portion 43 are in the width direction at both axial ends of the cup-side third uneven portion 43. It is inclined in a direction away from each other toward the outer side (the width dimension between the circumferential side surfaces is increased toward the outer side in the width direction). This prevents the cup-side third uneven portion 43, the drive-side uneven portion 39a, and the driven-side uneven portion 40a from hitting each other.

The elastic member 18a is composed of a pair of elastic bodies 46a and 46b. As shown in FIG. 14, each elastic body 46a (46b) has a concave (U-shaped) end surface shape (inner circumferential surface) at a plurality of circumferential positions on the axial side surface of the annular coupling plate portion 33a. Are provided with engaging pieces 34a, 34a recessed outward in the radial direction, and provided with an outer diameter side uneven portion 35a on the outer peripheral surface and an inner diameter side uneven portion 36a on the inner peripheral surface. That is, the outer diameter side uneven portion 35a has the outer diameter side portion of each engaging piece 34a, 34a as a convex portion, and the portion between adjacent engaging pieces 34a, 34a as a concave portion. On the other hand, the inner diameter side uneven portion 36a is a portion between the inner side surfaces of the circumferential wall portions 37a, 37a of the adjacent engagement pieces 34a, 34a (a portion including a pair of circumferential wall portions 37a, 37a). ) Is a convex portion, and the concave portion is a portion recessed radially outward of the inner peripheral surface of each engagement piece 34a, 34a. In the case of the present embodiment, as shown in FIG. 10, the circumferential dimension T _37a of the circumferential wall portions 37a, 37a constituting the engaging pieces 34a, 34a is the cup side third uneven portion 43 and the drive side uneven portion. It is larger than the size t of the circumferential clearance between the other end portion in the axial direction of the portion 39a (the one axial end portion of the driven side uneven portion 40a) (T _37a > t). Also, referring to FIGS. 11 to 14, the circumferential dimension D _35a of the convex portion of the outer diameter side concave and convex portion _35a is the circumference of the concave portion constituting the cup side first concave and convex portion 41 and the cup side second concave and convex portion 42. larger than the dimension _{D 30a} with _{(D 35a>} D _30a), the circumferential dimension _{d 36a} of the concave portion on the inner diameter side concave-convex portion 36a has a circumferential dimension _{d 39a} of the convex portion constituting the driving-side uneven portion 39a, It is smaller than any one of the circumferential dimensions d _40a of the convex portions constituting the driven side uneven portion 40a (d _36a <d _39a = d _40a ).

And among the elastic bodies 46a and 46b, the outer diameter side uneven portion 35a of one elastic body 46a corresponding to the drive side elastic body (the right side in FIG. 9) is engaged with the cup-side first uneven portion 41. Similarly, the inner diameter side uneven portion 36a is engaged with one axial end portion of the drive side uneven portion 39a. As a result, the circumferential wall portions 37a and 37a (corresponding to the driving side clamping piece of the present invention) constituting one elastic body 46a are connected to the circumferential side surface of the convex portion constituting the driving side uneven portion 39a and the coupling 30a. Between the projecting portions 45, 45 provided at one end in the axial direction. Further, the connecting plate portion 33a of one elastic body 46a is sandwiched between the other axial side surface of the driving side flange 23a and one axial end surface of the coupling 30a. Further, of the elastic bodies 46a and 46b, the outer diameter side uneven portion 35a of the other elastic body 46b corresponding to the driven side elastic body (left side in FIG. 9) is engaged with the cup side second uneven portion 42. At the same time, the inner diameter side uneven portion 36a is engaged with the other axial end of the driven side uneven portion 40a. As a result, the circumferential wall portions 37a and 37a (corresponding to the driven side clamping piece of the present invention) constituting the other elastic body 46b, the circumferential side surface of the convex portion constituting the driven side uneven portion 40a, and the cup The protrusions 45 are provided at the other end in the axial direction of the ring 30a and are sandwiched between the side surfaces in the circumferential direction. Further, the connecting plate portion 33a of the other elastic body 46b is sandwiched between one axial side surface of the driven side flange portion 29a and the other axial end surface of the coupling 30a.

In addition, between the outer diameter side uneven part 35a and the cup side first uneven part 41 of one elastic body 46a, between the inner diameter side uneven part 36a and the driving side uneven part 39a, and the other elastic body. It is also possible to provide circumferential gaps between the outer diameter side uneven portion 35a of 46b and the cup side second uneven portion 42 and between the inner diameter side uneven portion 36a and the driven side uneven portion 40a. . In this case, the circumferential clearance between the outer diameter side uneven portion 35a of one elastic body 46a (the other elastic body 46b) and the cup side first uneven portion 41 (cup side second uneven portion 42), and the same The circumferential clearance between the inner diameter side uneven portion 36a and the drive side uneven portion 39a (driven side uneven portion 40a) is the same as that of the cup side third uneven portion 43 and the drive side uneven portion 39a (driven side uneven portion 40a). Each of the gaps in the circumferential direction is made smaller.

Further, the connecting plate portion 33a of one elastic body 46a is sandwiched between the one axial side surface of the driving side flange 23a of the driving side transmission member 19a and the other axial end surface of the coupling 30a in the axial direction, It may be compressed in the axial direction, or may be provided via a gap between the other axial side surface of the driving side flange 23a of the driving side transmission member 19a and one axial end surface of the coupling 30a. .
Similarly, the connecting plate portion 33a of the other elastic body 46b is also between the one axial side surface of the driven side flange 29a of the driven side transmission member 25a and the other axial end surface of the coupling 30a in the axial direction. It may be sandwiched and compressed in the axial direction, or through a gap between one axial side surface of the driven side flange 29a of the driven side transmission member 25a and the other axial end surface of the coupling 30a. It may be provided.

In the torque transmission joint 16a of the present embodiment as described above, the cup-side third uneven portion 43 is provided around the other axial end of the drive-side uneven portion 39a and one axial end of the driven-side uneven portion 40a. Each is engaged with a directional gap interposed. The cup-side first uneven portion 41 engages with one end of the drive-side uneven portion 39a in the axial direction with the circumferential wall portions 37a and 37a constituting one elastic body 46a interposed therebetween, and the cup-side uneven portion 41a. The second side uneven portion 42 is engaged with the other end portion in the axial direction of the driven-side uneven portion 40a with the circumferential wall portions 37a and 37a constituting the other elastic body 46b interposed. Furthermore, the dimensions of each part are regulated as described above. Therefore, when the torque transmitted between the output shaft of the electric motor 7 (see FIG. 1) and the worm shaft 6a is relatively small, the rotational torque of the output shaft 12a is reduced to one of the driving side uneven portion 39a and the other side. The elastic body 46a is transmitted to the one elastic body 46a from the engaging portion with the inner diameter side uneven portion 36a, and further, the outer diameter side uneven portion 35a of the one elastic body 46a and the cup side first uneven portion 41 are engaged. Is transmitted to the coupling 30a. The torque transmitted to the coupling 30a is transmitted from the engagement portion between the cup-side second uneven portion 42 and the outer-diameter-side uneven portion 35a of the other elastic body 46b to the other elastic body 46b. The elastic body 46b is transmitted to the worm shaft 6a from the engagement portion between the inner-side uneven portion 36a and the driven-side uneven portion 40a.

On the other hand, when the torque transmitted between the output shaft 12a and the worm shaft 6a increases, the circumferential wall portions 37a and 37a constituting both elastic bodies 46a and 46b are crushed elastically in the circumferential direction. And the circumferential direction side surface of the convex parts 32a and 32a which comprise the cup side 3rd uneven part 43, the circumferential direction side surface of the convex part which comprises the drive side uneven part 39a, and the convex part which comprises the to-be-driven side uneven part 40a Directly contact (contact) each other. In this state, most of the rotational torque of the output shaft 12a is transmitted to the coupling 30a from the engaging portion of the driving side uneven portion 39a and the cup side third uneven portion 43, and the torque transmitted to the coupling 30a is transmitted. Most of the light is transmitted to the worm shaft 6a from the engaging portion between the cup-side third uneven portion 43 and the driven-side uneven portion 40a.

According to this embodiment, torque transmission between the output shaft 12a and the worm shaft 6a is performed according to the magnitude of torque to be transmitted, as in the case of the first embodiment described above. The characteristics can be divided into two stages, and the operational feeling of the steering wheel 1 (see FIG. 9) can be improved. Further, in the case of the present embodiment, even when the worm shaft 6a is oscillated and displaced, or when the center axis of the worm shaft 6a and the center axis of the output shaft 12a become eccentric, etc., the coupling 30a is connected to the worm shaft 6a. By tilting with respect to the center axis of 6a and the center axis of the output shaft 12a, torque transmission between the output shaft 12a and the worm shaft 6a can be performed smoothly.

In the present embodiment, the elastic member 18a is composed of a pair of elastic bodies 46a and 46b. And the connecting plate part 33a which comprises one elastic body 46a of both elastic bodies 46a and 46b is elastic between the axial direction other side surface of the drive side collar part 23a, and the axial direction one end surface of the coupling 30a. The connecting plate portion 33a constituting the other elastic body 46b is elastically sandwiched between one axial side surface of the driven side flange 29a and the other axial end surface of the coupling 30a. Therefore, even when the worm shaft 6a is displaced by oscillating, or when the center axis of the worm shaft 6a and the center axis of the output shaft 12a are decentered, etc., the elastic body 46a constituting the elastic member 18a ( 46b) can be prevented from inclining with respect to a virtual plane orthogonal to the axial direction.
The configuration and operation of other parts are the same as those in the first embodiment described above.

[Modification of Embodiment]
FIG. 15 is a modification of the above-described embodiment. In FIG. 15, reference numeral 54 denotes a transmission portion coupling member, and six pins 53 are provided on the same circumference and at equal intervals on the outer edge portions of both sides of the disk-like plate portion. Six driven-side pin insertion holes 52 are provided on the motor-side end surface of the driven-side transmission member 25 at positions facing the pins 53, and the pin 53 and the end surface of the driving-side transmission member 19 on the worm shaft side are provided. Six drive-side pin insertion holes 51 are provided at opposing positions. Tubular elastic members 50 are fitted in the driven-side pin insertion holes 52 and the driving-side pin insertion holes 51, respectively, and the pins 53 of the transmission portion coupling member 54 are fitted in the through holes of the elastic members 50, respectively. ing.
Also by the configuration of this modified example, the same operation and effect as the above-described embodiment can be obtained.

This application includes Japanese Patent Application No. 2014-196240 filed on Sep. 26, 2014, Japanese Patent Application No. 2014-265909 filed on Dec. 26, 2014, and Japanese Patent Application No. 2015-24871 filed on Feb. 12, 2015. The contents of which are incorporated herein by reference.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Housing 4 Worm wheel 5 Worm tooth | gear 6, 6a Worm shaft 7 Electric motor 8 Worm 9a, 9b Rolling bearing 10 Pressing piece 11 Coil spring 12, 12a Output shaft 13 Spline hole 14 Spline shaft part 15 Preload provision Mechanism 16 Joint for torque transmission 17 Output shaft body 18, 18a Elastic member 19, 19a Drive side transmission member 20, 20a Drive side transmission part 21 Drive side first uneven part 22 Drive side second uneven part 23, 23a Drive side flange 24 Worm shaft main body 25, 25a Driven side transmission member 26, 26a Driven side transmission part 27 Driven side first uneven part 28 Driven side second uneven part 29, 29a Driven side flange part 30, 30a Coupling 31 Cup side uneven part 32, 32a Convex part 3 , 33a Connecting plate part 34, 34a Engagement piece 35, 35a Outer diameter side uneven part 36, 36a Inner diameter side uneven part 37, 37a Circumferential wall part 38 Through hole 39, 39a Drive side uneven part 40, 40a Drive side uneven part Part 41 Cup side first uneven part 42 Cup side second uneven part 43 Cup side third uneven part 44 Tube part 45 Projection part 46a, 46b Elastic body 50 Elastic member 51 Drive side pin insertion hole 52 Driven side pin insertion hole 53 Pin 54 Transmitter coupling member

Claims (11)

1. A torque transmission joint that transmits torque between ends of a drive shaft and a driven shaft that are arranged in series with each other in the axial direction,
   A coupling provided with a cup-side uneven portion formed by alternately arranging concave portions and convex portions over the entire circumference on one of the inner and outer peripheral surfaces;
   An elastic member made of an elastic material having driving side clamping pieces provided at a plurality of locations in the circumferential direction and driven side clamping pieces provided at a plurality of locations in the circumferential direction;
   Provided directly or through other members at the end of the drive shaft, and on both the inner and outer peripheral surfaces facing the cup-side uneven portion, the concave portion and the convex portion are alternately arranged over the entire circumference. A drive-side transmission portion provided with a drive-side uneven portion disposed on
   Provided directly or via other members at the end of the driven shaft, and on both the inner and outer peripheral surfaces facing the cup-side concavo-convex portion, the concave portion and the convex portion are provided over the entire circumference. A driven-side transmission portion provided with driven-side uneven portions that are alternately arranged, and
   A part of the driving-side uneven part in the axial direction is engaged with the cup-side uneven part with a circumferential clearance interposed therebetween, and the remaining part in the axial direction of the driving-side uneven part is on the cup side. Engaged with the concavo-convex part in a state of interposing each driving side clamping piece,
   A part in the axial direction of the driven-side uneven part is engaged with the cup-side uneven part with a circumferential gap interposed therebetween, and the axial remaining part of the driven-side uneven part is The cup side uneven part is engaged with each driven side clamping piece interposed therebetween,
   Joint for torque transmission.
2. The circumferential dimension of each driving side clamping piece is larger than the circumferential gap between a part in the axial direction of the driving side uneven part and the cup side uneven part,
   The circumferential dimension of each said driven side clamping piece is made larger than the circumferential clearance between the axial part of the said driven side uneven | corrugated | grooved part and the said cup side uneven | corrugated | grooved part. The described torque transmission joint.
3. The drive-side uneven portion is composed of a drive-side first uneven portion formed on one half of the axial direction and a drive-side second uneven portion formed on the other half of the axial direction. The one concavo-convex portion is engaged with one end portion in the axial direction of the cup-side concavo-convex portion with a circumferential gap interposed therebetween, and the second concavo-convex portion on the driving side is a portion near the one end in the axial direction of the cup-side concavo-convex portion. Are engaged with each of the drive side clamping pieces interposed therebetween,
   The driven-side uneven portion is composed of a driven-side first uneven portion formed in the other half portion in the axial direction and a driven-side second uneven portion formed in the axial half portion, The driven side first uneven portion is engaged with the other end portion in the axial direction of the cup side uneven portion with a circumferential gap interposed therebetween, and the driven side second uneven portion is the cup side uneven portion. The torque transmission joint according to claim 1, wherein the driven side clamping pieces are engaged with a portion closer to the other axial end of each of the first and second driven side clamping pieces.
4. The torque transmission joint according to claim 3, wherein the elastic member integrally includes the driving side clamping pieces and the driven side clamping pieces.
5. At least one of the axial end portions of the coupling, the opposite circumferential side surfaces of the convex portions constituting the cup-side concavo-convex portion are separated from each other toward the end edge of the coupling. The torque transmission joint according to claim 3 or 4, which is inclined in a direction.
6. Each driving side clamping piece is disposed adjacent to the driving side first uneven portion in the axial direction,
   The torque transmission joint according to any one of claims 3 to 5, wherein each of the driven side clamping pieces is disposed adjacent to the driven side first uneven portion in the axial direction.
7. The cup-side uneven portion is formed on the one axial end portion of the cup side first uneven portion, the cup-side second uneven portion formed on the other axial end portion, and the cup side formed on the axial intermediate portion. It consists of a third uneven part,
   The cup side first concavo-convex part is engaged with each driving side clamping piece interposed between one axial end part or intermediate part of the driving side concavo-convex part,
   The cup-side second concavo-convex part is engaged with the driven-side concavo-convex part in the state where the driven-side clamping pieces are interposed between the other axial end or the intermediate part of the driven-side concavo-convex part,
   One end in the axial direction of the cup-side third concavo-convex part is engaged with the other end in the axial direction of the driving-side concavo-convex part with a circumferential gap interposed therebetween, and the axis of the cup-side third concavo-convex part 3. The torque transmission joint according to claim 1, wherein the other end portion in the direction is engaged with one end portion in the axial direction of the driven-side uneven portion with a circumferential clearance interposed therebetween.
8. The said elastic member is comprised from the drive side elastic body provided with each said drive side clamping piece which is a mutually separate body, and the driven side elastic body provided with each said driven side clamping piece. The described torque transmission joint.
9. At both ends of the cup-side third concavo-convex portion in the axial direction, both opposite circumferential side surfaces of the convex portions constituting the cup-side third concavo-convex portion are the cup-side third concavo-convex portions. The joint for torque transmission according to claim 7 or 8, wherein the joint is inclined in a direction away from each other toward an end edge of the portion.
10. In the drive-side elastic body, each drive-side clamping piece is provided at a plurality of locations in the circumferential direction on the axial side surface of the annular connection plate portion,
    In the driven-side elastic body, the driven-side holding pieces are provided at a plurality of locations in the circumferential direction on the axial side surface of the annular connecting plate portion,
    The connecting plate portion of the driving side elastic body is disposed between the axial side surface of the driving side transmission portion and one axial end surface of the coupling,
    The connection plate portion of the driven-side elastic body is disposed between the axial side surface of the driven-side transmission portion and the other axial end surface of the coupling according to any one of claims 7 to 9. The described torque transmission joint.
11. A housing that is supported by a fixed part and does not rotate;
    A steering rotation shaft that is rotatably provided with respect to the housing, is rotated by an operation of a steering wheel, and gives a steering angle to the steered wheels in accordance with the rotation;
    A worm wheel that is supported concentrically with the steering rotary shaft and rotates together with the steering rotary shaft inside a part of the steering rotary shaft inside the housing;
    A worm tooth is provided at an axial intermediate portion of the worm shaft, and both end portions in the axial direction of the worm shaft are rotatably supported by the bearings by bearings in a state where the worm tooth is engaged with the worm wheel. Warm and
    An electric motor for rotationally driving the worm,
    In the electric power steering device in which the output shaft of the electric motor and the worm shaft are connected by a torque transmission joint so that torque can be transmitted,
    The electric power steering apparatus, wherein the torque transmission joint is the torque transmission joint according to any one of claims 1 to 10.

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