WO2016175266A1

WO2016175266A1 - Joint for torque transmission and worm reduction gear

Info

Publication number: WO2016175266A1
Application number: PCT/JP2016/063300
Authority: WO
Inventors: 亮大澤; 瀬川　徹
Original assignee: 日本精工株式会社
Priority date: 2015-04-28
Filing date: 2016-04-27
Publication date: 2016-11-03
Also published as: JPWO2016175266A1; JP6551522B2

Abstract

According to the present invention, a half portion of a drive-side uneven portion (26) on one axial side and a half portion of a driven-side uneven portion (32) on the other axial side are lightly pressed, in a radial direction, into an axial middle portion of a cup-side uneven portion (35), and a half portion of the drive-side uneven portion (26) on the other axial side and a half portion of the driven-side uneven portion (32) on the one axial side have radial gaps interposed between said half portions and both axial ends of the cup-side uneven portion (35). The drive-side and driven-side uneven portions (26, 32) are engaged with the cup-side uneven portion (35) with a circumferential gap interposed between the drive-side and driven-side uneven portions (26), (32) and the cup-side uneven portion (35).

Description

Torque transmission joint and worm reducer

The torque transmission joint of the present invention is incorporated in various mechanical devices and is used to transmit torque between the drive shaft and the driven shaft. The worm speed reducer of the present invention is incorporated in, for example, an electric power steering device.

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). Yes. Among such power steering devices, an electric power steering device that uses an electric motor as an auxiliary power source has also started to spread in recent years. In such an electric power steering apparatus, auxiliary power of the electric motor is applied to the steering shaft that rotates as the steering wheel is operated or a member that is displaced as the steering shaft rotates through the reduction gear. . The direction of the auxiliary power applied from the electric motor is the same as the force applied from the steering wheel. As the speed reducer, a worm speed reducer is generally used. In the case of an electric power steering device using a worm reduction gear, a worm that is rotationally driven by an electric motor and a worm wheel mesh with each other. The worm wheel rotates together with a rotating shaft that is a member that is engaged with a steering shaft or a member that is displaced along with the rotation of the steering shaft so that power can be transmitted. Thus, the auxiliary power of the electric motor can be transmitted to the rotating shaft. However, in the case of a worm reducer, if no measures are taken, an unpleasant noise called a rattling noise caused by backlash existing in the meshing part of the worm and the worm wheel when changing the rotation direction of the rotating shaft. May occur.

In order to suppress the generation of such rattling noise, it has been conventionally considered to elastically press the worm toward the worm wheel by an elastic member such as a spring. 18 to 19 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. Also, worm teeth 6 are provided at the axially intermediate portion of the worm 8. In the state where the worm teeth 6 and the tooth portions 5 formed on the outer peripheral surface of the worm wheel 4 are engaged with each other, two axial positions of the worm 8 sandwiching the worm teeth 6 (both axial positions of the worm teeth 6) However, it is rotatably supported in the housing 3 by a pair of

rolling bearings

9a and 9b such as deep groove type ball bearings. Such a worm 8 can be rotationally driven by the output shaft of the electric motor 7 connected to the base end portion. Further, a pressing piece 10 is fitted on a portion protruding from the rolling bearing 9 a at the tip of the worm 8. An elastic member such as a coil spring 11 is provided between the pressing piece 10 and the housing 3. The coil spring 11 presses the worm teeth 6 of the worm 8 toward the teeth 5 of the worm wheel 4 via the pressing piece 10. With such a configuration, backlash between the worm teeth 6 and the tooth portions 5 is suppressed, and generation of rattling noise is suppressed.

In the case of the conventional structure as described above, it is possible to suppress the occurrence of rattling noise at the meshing portion between the worm tooth 6 and the tooth portion 5, but the distal end portion of the output shaft 12 of the electric motor 7 and the proximal end portion of the worm 8. There is room for improvement in order to suppress the abnormal noise generated at the joint. This point will be described below. In the case of the illustrated structure, a spline hole 13 is formed at the base end of the worm 8 in order to couple the tip of the output shaft 12 of the electric motor 7 and the base end of the worm 8 so that torque can be transmitted. Yes. The spline hole 13 opens toward the base end surface of the worm 8. On the other hand, a spline shaft portion 14 is formed at the distal end portion of the output shaft 12. Then, the spline shaft portion 14 and the spline hole 13 are spline-engaged, so that the output shaft 12 and the worm 8 are coupled so as to transmit torque.

If the spline shaft portion 14 and the spline hole 13 are spline-engaged without any circumferential clearance (without backlash), the coupling portion (spline engagement) between the distal end portion of the output shaft 12 and the proximal end portion of the worm 8 No abnormal noise occurs in the joint section). However, as shown in FIG. 17, the coil spring 11 elastically presses the worm tooth 6 of the worm 8 toward the tooth part 5 of the worm wheel 4, thereby causing backlash between the worm tooth 6 and the tooth part 5. In the case of the structure to suppress, since it is necessary to swing and displace the worm 8, the backlash of the spline engaging portion cannot be completely eliminated and it is difficult to prevent the generation of abnormal noise.

Patent Document 2 describes a structure in which the swing displacement of the worm shaft can be made smooth by connecting the output shaft of the electric motor and the worm shaft via a metal-made cylindrical power transmission member. . 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 of each 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, the present invention can prevent the generation of noise between the drive shaft and the driven shaft, and the central axes of the drive shaft and the driven shaft are inconsistent with each other. Another object of the present invention is to realize a torque transmission joint that can smoothly transmit torque between a drive shaft and a driven shaft.

The torque transmission joint and the torque transmission joint of the worm reducer according to the present invention are arranged between one axial end of the drive shaft and the other axial end of the driven shaft, which are arranged in series with respect to the axial direction. The torque is transmitted by the motor, and includes a coupling, a drive side transmission unit, and a driven side transmission unit.
The coupling is formed on one of the inner and outer peripheral surfaces in the radial direction (in the case where this one peripheral surface is the inner peripheral surface, inward in the radial direction. The cup side uneven | corrugated | grooved part which arrange | positions the cup side convex part which protrudes in the direction outward.
The drive-side transmission portion is provided at one axial end portion of the drive shaft, and has a radial direction (a circumference facing the cup-side uneven portion) on a peripheral surface facing the cup-side uneven portion of both inner and outer peripheral surfaces. When the surface is an outer peripheral surface, the drive side is formed by arranging drive-side convex portions projecting radially outward (or radially inward when the surface is also an inner peripheral surface) at a plurality of locations in the circumferential direction. An uneven portion is provided.
The driven-side transmission portion is provided at the other axial end portion of the driven shaft, and a radial direction (in the cup-side uneven portion on the cup-side uneven portion) of the inner and outer peripheral surfaces facing the cup-side uneven portion. When the opposing peripheral surface is the outer peripheral surface, the driven-side convex portions that protrude radially outwardly (or radially inward when the inner peripheral surface is the same) are arranged at a plurality of locations in the circumferential direction. The driven side uneven portion is provided.
Then, the drive-side concavo-convex part is engaged with the other axial half of the cup-side concavo-convex part (the drive-side convex part and the axial-side other half of each cup-side convex part are circumferentially connected). And the driven-side uneven portion and the one-side half of the cup-side uneven portion are engaged with each other (the driven-side convex portions and the cup-side convex portions The one half of the axial direction is alternately arranged in the circumferential direction).
In addition, among the driving side convex portions and the cup side convex portions, one axial half side of the engaging portion between the driving side concave and convex portion and the other axial half of the cup side concave and convex portion. Lightly press-fitting the front end surface of the first convex portion which is one of the convex portions into the bottom surface of the first concave portion existing between the second convex portions which are the other convex portions, and the driving side uneven portion and the cup The front end surface of the first convex portion is opposed to the bottom surface of the first concave portion via a radial gap in the other half portion in the axial direction of the engaging portion with the other half portion in the axial direction of the side uneven portion. . At the same time, a circumferential clearance is interposed between the driving side uneven portion and the cup side uneven portion.
Further, the driven-side convex portions and the cup-side convex portions at the other axial half portion of the engaging portion between the driven-side concave-convex portion and the one-side half portion in the axial direction of the cup-side concave-convex portion, Lightly press the tip surface of the third convex portion that is one of the convex portions into the bottom surface of the second concave portion that exists between the fourth convex portions that are the other convex portions, and the driven side uneven portion And the one side half of the engagement portion between the cup side uneven portion and the one axial half of the cup side, the tip surface of the third convex portion faces the bottom surface of the second concave portion via a radial gap. I am letting. At the same time, a circumferential clearance is interposed between the driven side uneven portion and the cup side uneven portion.

When implementing the torque transmission joint of the present invention as described above, the tip surface of the second convex portion and the bottom surface of the concave portion existing between the first convex portions, and the A radial clearance is provided between the distal end surface of the fourth convex portion and the bottom surface of the concave portion existing between the third convex portions over the entire axial width of the driving side and driven side convex portions. Intervene.
Further, when implementing the torque transmission joint of the present invention as described above, a part of the first convex portions (for example, every other one in the circumferential direction) may be replaced with the first concave portion. The third convex portion may be lightly press-fitted into the bottom surface of the second concave portion and may be configured to be lightly press-fitted into the bottom surface of the second concave portion. In this case, the diameter of the remaining first and third convex portions extends between the front end surfaces of the remaining first and third convex portions and the bottom surfaces of the first and second concave portions over the entire axial width of the remaining first and third convex portions. A directional gap is interposed.

When implementing the torque transmission joint of the present invention as described above, specifically, for example, each cup side convex portion includes a high tooth height convex portion formed in an axial intermediate portion, and both axial end portions. And a low tooth height convex portion having a tooth height in the radial direction smaller than that of the high tooth height convex portion.
Then, lightly press-fitting the front end surface of the other axial end portion of the high tooth height convex portion into the bottom surface of the driving side concave portion (the one side half portion thereof) existing between the driving side convex portions, The tip surface of the low tooth height convex portion (on the other side in the axial direction) formed at the other axial end portion of the both axial end portions of each cup side convex portion is the driving side concave portion (the other half portion in the axial direction of the driving side). ) With a radial gap between them.
Moreover, while lightly press-fitting the front end surface of one axial end portion of the high tooth height convex portion into the bottom surface of the driven side concave portion (the other half portion in the axial direction) existing between the driven side convex portions. The tip surface of the low tooth height convex portion formed at one axial end portion of the axially opposite end portions of each cup-side convex portion is the bottom surface of each driven-side concave portion (one axial half thereof). It is made to oppose through a radial clearance.
That is, in the case of the invention described in the claims, the other half in the axial direction of the convex portion on the cup side (the other axial end portion of the high tooth height convex portion and the low tooth height convex portion on the other side in the axial direction) Is the first convex portion, the driving side convex portion is the second convex portion, the driving side concave portion is the first concave portion, the axial one side half of the cup side convex portion (one axial end portion of the high tooth height convex portion and A low tooth height convex portion on one axial side) corresponds to the third convex portion, the driven side convex portion corresponds to the fourth convex portion, and the driven side concave portion corresponds to the second concave portion.

Or, for example, each drive side convex portion is formed on the drive side high tooth height convex portion formed on the one half portion in the axial direction and this drive side high tooth height convex portion formed on the other half portion in the axial direction. And a drive-side low tooth height convex portion having a smaller tooth height in the radial direction.
Further, each driven side convex portion includes a driven side high tooth height convex portion formed on the other half portion in the axial direction and this driven side high tooth height convex portion formed on the one half portion in the axial direction. The driven side low tooth height convex portion is smaller in tooth height in the radial direction than the portion.
And while lightly press-fitting the front end surface of the drive-side high tooth height convex portion into the bottom surface of the cup-side concave portion (one side portion of the other half portion in the axial direction thereof) existing between the cup-side convex portions, The drive-side low tooth height convex portion is opposed to the bottom surface of the cup-side concave portion (the other side portion of the other half portion in the axial direction) via a radial gap.
Further, the driven side high tooth height convex portion is lightly press-fitted into the bottom surface of the cup side concave portion (the other side portion of one half of the axial direction of the cup side), and the driven side low tooth height convex portion. Is opposed to the bottom surface of the cup-side recess (the one side half in the axial direction) via a radial gap.
That is, the drive-side convex portion is driven to the first convex portion, the cup-side concave portion on the other axial half is the second convex portion, and the cup-side concave portion on the other axial half is driven to the first concave portion. The side convex portion corresponds to the third convex portion, the axial one side half of the cup side convex portion corresponds to the fourth convex portion, and the axial one side half of the cup side concave portion corresponds to the second concave portion.

In the case of implementing the torque transmission joint of the present invention as described above, preferably, the driving side concavo-convex part is located at the other half in the axial direction of the cup side concavo-convex part, and the center between the driving shaft and the driven shaft. Drive in which the width dimension in the circumferential direction increases toward the other side in the axial direction between the circumferential side surface of each driving side convex portion and the circumferential side surface of each cup side convex portion in a state where the shafts are matched. Engage with the side gap interposed. In addition, each driven-side convex portion in a state where the driven-side uneven portion is aligned with one half in the axial direction of the cup-side uneven portion, and the center axes of the driving shaft and the driven shaft are aligned with each other. Between the circumferential side surface and the circumferential side surface of each of the cup-side convex portions, with the driven side gap increasing in width in the circumferential direction toward one side in the axial direction.

In the case of carrying out such an invention, preferably, the circumferential side surface of each cup side convex portion has the largest width dimension in the circumferential direction of each cup side convex portion at the axial middle portion, and both axial end portions. The crowning shape is inclined in a direction that decreases as it goes to (inclined in a direction in which the protrusion amount in the circumferential direction decreases as it approaches the end in the axial direction).

When carrying out such an invention, for example, both side surfaces in the circumferential direction of the convex portions on the driving side and the driven side can be flat surfaces parallel to each other. The width dimension of the convex portion in the circumferential direction can also be a crowning shape that is inclined in a direction that is the largest (thick) in the middle portion in the axial direction and the smaller (thinner) in the axial direction.

In the case of carrying out the invention as described above, preferably, the axial direction of the circumferential side surfaces of the respective drive-side convex portions in a state where the central axes of the drive shaft and the driven shaft are aligned with each other. One end part and the circumferential side surface of the cup-side convex part are brought into contact or close to each other without rattling in the circumferential direction. In addition, in a state where the central axes of the drive shaft and the driven shaft are aligned with each other, the other axial end of the circumferential side surface of each driven-side convex portion and the circumference of each cup-side convex portion The directional side surfaces are brought into contact or close to each other without rattling in the circumferential direction.

Preferably, when the invention as described above is carried out, one of the inner and outer peripheral surfaces of the coupling is formed with a cup-side protrusion that protrudes in the radial direction, and the cup-side protrusion The part is located between the driving side transmission part and the driven side transmission part in the axial direction.

The worm speed reducer according to the present invention includes, for example, a housing, a worm wheel, a worm, and an electric motor.
The worm wheel is rotatably supported with respect to the housing.
The worm is supported rotatably with respect to the housing in a state in which worm teeth provided at an intermediate portion in the axial direction are engaged with the worm wheel.
The electric motor is for rotationally driving the worm.
The worm and the output shaft of the electric motor are connected by a torque transmission joint so that torque can be transmitted.
In particular, in the worm reduction gear of the present invention, the torque transmission joint is the torque transmission joint of the present invention as described above. In this case, the output shaft of the electric motor corresponds to the drive shaft, and the worm shaft corresponds to the driven shaft.
Preferably, when implementing the worm speed reducer of the present invention as described above, the tip of the worm (the end opposite to the side connected to the output shaft of the electric motor via the torque transmission joint) A preload applying mechanism that elastically presses the worm toward the worm wheel is provided between the housing and the housing.

According to the torque transmission joint and the worm speed reducer of the present invention as described above, it is possible to prevent the generation of noise between the drive shaft and the driven shaft, and the center between the drive shaft and the driven shaft. Even if the shafts do not coincide with each other, torque transmission between the drive shaft and the driven shaft can be performed smoothly.
That is, in the case of the present invention, the one side half in the axial direction of the engaging portion between the driving side uneven portion and the other axial half of the cup side uneven portion, the drive side convex portion and the cup side convex portion The tip surface of the first convex portion that is one of the convex portions is lightly press-fitted into the bottom surface of the first concave portion that exists between the second convex portions that are the other convex portions. At the same time, the driven-side convex portion and the cup-side convex portion at the other half portion in the axial direction of the engaging portion between the driven-side uneven portion and the one-side half portion in the axial direction of the cup-side uneven portion. The tip surface of the third convex portion which is one of the convex portions is lightly press-fitted into the bottom surface of the second concave portion existing between the fourth convex portions which are the other convex portions. Therefore, at the start of torque transmission between the drive shaft and the driven shaft, one side half in the axial direction of the engaging portion between the drive side uneven portion and the other half portion in the axial direction of the cup side uneven portion. A contact portion between the tip surface of the first convex portion and the bottom surface of the first concave portion slides in the circumferential direction, and the circumferential side surface of each driving side convex portion and each cup side convex portion. Abuts (contacts) with the circumferential side surface. Similarly, in the other axial half of the engaging portion between the driven side uneven portion and the axial one side half of the cup side uneven portion, the tip surface of the third convex portion and the second concave portion The contact portion with the bottom surface slides in the circumferential direction, and the circumferential side surface of each driven-side convex portion and the circumferential side surface of each cup-side convex portion abut each other. The momentum of these collisions is weakened by the friction acting on the contact portion between the tip surfaces of the first and third convex portions and the bottom surfaces of the first and second concave portions. For this reason, an unusual noise such as an unpleasant rattling noise is generated at the abutting portion (contact portion) between the circumferential side surface of each convex portion on the driving side and the driven side and the circumferential side surface of each convex portion on the cup side. Can be prevented.

Further, in the case of the present invention, the front end surface of the first convex portion is the first half portion in the other half portion in the axial direction of the engagement portion between the driving side uneven portion and the other half portion in the axial direction of the cup side uneven portion. The bottom surface of one recess is opposed to each other with a gap in the radial direction, and the one side half in the axial direction of the engaging portion between the driven side uneven portion and the one axial half of the cup side uneven portion, The tip surface of the third convex portion is opposed to the bottom surface of the second concave portion with a radial gap interposed therebetween. Furthermore, a circumferential clearance is interposed between the driving-side and driven-side uneven portions and the cup-side uneven portion. Therefore, when the center axes of the drive shaft and the driven shaft are not coincident with each other, a coupling is formed between the drive shaft and the driven shaft based on the presence of the radial gap and the circumferential gap as described above. Tilt with respect to at least one of the axes. Thereby, torque can be transmitted smoothly between the drive shaft and the driven shaft.

The principal part expanded sectional view which shows the 1st example of embodiment. The a section enlarged view of FIG. The end view of a drive side transmission member. FIG. 3B is a sectional view taken along line bb in FIG. 3A. The end view of a driven side transmission member. FIG. 4C is a sectional view taken along the line cc of FIG. 4A. End view of the coupling. Dd sectional drawing of FIG. 5A. FIG. 9 is a diagram corresponding to the ee cross section of FIG. 1 showing a second example of the embodiment. FIG. 6F is a sectional view taken along line ff in FIG. 6A. The figure similar to FIG. 2 which shows the 3rd example of embodiment. The figure similar to FIG. 2 which shows the 4th example of embodiment. The figure similar to FIG. 2 which shows the 4th example of embodiment. The figure similar to FIG. 2 which shows the 4th example of embodiment. The figure similar to FIG. 2 which shows the 4th example of embodiment. The figure similar to FIG. 2 which shows the 4th example of embodiment. The figure similar to FIG. 2 which shows the 4th example of embodiment. The figure similar to FIG. 2 which shows the 5th example of embodiment. Sectional drawing of a coupling. The figure similar to FIG. 2 which shows the 6th example of embodiment. The partial expanded view of the metal core which comprises a coupling. The partial longitudinal section side view showing an example of the steering device for cars. FIG. 19 is an enlarged gg sectional view of FIG. 18 showing an example of a conventional structure of an electric power steering device.

[First Example of Embodiment]
1 to 5 show a first example of an embodiment of the present invention. The worm speed reducer 15 of this example includes a housing 3, a worm wheel 4, a worm 8a that is a driven shaft, and an electric motor 7 (see FIGS. 18 to 19).

The worm wheel 4 is rotatably supported inside the housing 3. A tooth portion 5 is formed on the outer peripheral surface of the worm wheel 4.

The worm 8a has two positions in the axial direction (positions on both sides of the worm teeth 6 in the axial direction) with the worm teeth 6 sandwiched between the teeth 5 of the worm wheel 4 in a state where the worm teeth 6 provided in the intermediate portion in the axial direction are engaged with the teeth 5 of the worm wheel 4. ) Is rotatably supported inside the housing 3 by a pair of rolling

bearings

9a and 9b (see FIG. 19) such as deep groove ball bearings. A preload applying mechanism 16 (see FIG. 19) including a pressing piece 10 and a coil spring 11 is provided between the tip of the worm 8a and the housing 3. The preload applying mechanism 16 presses the worm teeth 6 provided on the worm 8 a toward the tooth portions 5 of the worm wheel 4. With such a configuration, backlash between the worm tooth 6 and the tooth portion 5 is suppressed, and generation of rattling noise is suppressed.

The electric motor 7 is supported and fixed to the housing 3. The distal end portion (one axial end portion, left end portion in FIG. 1) of the output shaft 12a, which is the drive shaft of the electric motor 7, is connected to the base end portion (other axial end portion, right end portion in FIG. 1) of the worm 8a. The As a result, the worm 8a can be driven to rotate by the electric motor 7.

The distal end portion of the output shaft 12a of the electric motor 7 and the proximal end portion of the worm 8a are coupled via a torque transmission joint 17 so that torque can be transmitted. The torque transmission joint 17 includes a drive side transmission unit 18, a driven side transmission unit 19, and a coupling 20.

The drive-side transmission unit 18 is configured by supporting and fixing a drive-side transmission member 22 provided separately from the output shaft main body 21 at the tip of the output shaft main body 21 of the output shaft 12a. The drive side transmission member 22 is made of a material such as a synthetic resin such as a polyamide resin or a sintered metal. The drive side transmission member 22 includes a drive side cylindrical portion 24, a drive side uneven portion 26, and a drive side flange 39. A driving side engagement hole 23 is formed at the center of the driving side cylindrical portion 24. The drive-side concavo-convex portion 26 is radially outward (radial direction) at equal intervals from one axial end portion of the outer peripheral surface of the drive-side cylindrical portion 24 to a plurality of intermediate portions (portions other than the other axial end portion). Drive-side

convex portions

25, 25 projecting to) are formed. The driving side flange 39 is provided at the other end in the axial direction of the outer peripheral surface of the driving side cylindrical portion 24 and has a ring shape that is continuous in the circumferential direction.

The drive side engagement hole 23 of the drive side cylindrical portion 24 is in a state in which relative rotation is prevented by an interference fit, spline engagement, key engagement, or the like on the outer peripheral surface of the distal end portion of the output shaft main body 21 (torque It is fixed by external fitting). As a result, the drive-side transmission member 22 is supported and fixed to the distal end portion of the output shaft main body 21. In the case of this example, both side surfaces in the circumferential direction of the drive-side

convex portions

25, 25 constituting the drive-side uneven portion 26 are flat surfaces parallel to each other (the width of each drive-side

convex portion

25a, 25a in the circumferential direction). The dimensions are the same in the axial direction).

The driven-side transmission portion 19 is formed by supporting and fixing a driven-side transmission member 28 provided separately from the worm shaft main body 27 at the base end portion of the worm shaft main body 27 of the worm 8a. The driven side transmission member 28 is made of a material such as a synthetic resin such as a polyamide resin or a sintered metal. The driven-side transmission member 28 includes a driven-side cylindrical portion 30, a driven-side uneven portion 32, and a driven-side flange portion 40. A driven side engagement hole 29 is formed at the center of the driven side cylindrical portion 30. The driven-side concavo-convex portions 32 are radially outwardly spaced from the other axial end of the outer peripheral surface of the driven-side cylindrical portion 30 to a plurality of circumferential locations in the axial intermediate portion (a portion excluding the one axial end). The driven-side

convex portions

31, 31 projecting in the direction (radial direction) are formed. The driven side flange 40 is provided at one axial end portion of the outer peripheral surface of the driven side cylindrical portion 30 and has an annular shape that is continuous in the circumferential direction.

In a state where the driven side engagement hole 29 of the driven side cylindrical portion 30 prevents relative rotation by an interference fit, spline engagement, key engagement or the like on the outer peripheral surface of the proximal end portion of the worm shaft main body 27. It is fitted and fixed (to allow torque transmission). As a result, the driven-side transmission member 28 is supported and fixed to the proximal end portion of the worm shaft main body 27. In the case of this example, both side surfaces in the circumferential direction of the driven-side

convex portions

31, 31 constituting the driven-side uneven portion 32 are flat surfaces parallel to each other (the circumference of each driven-side

convex portion

31, 31. The width dimension in the direction is the same in the axial direction).

The coupling 20 includes, for example, a metal material such as sintered metal, a synthetic resin such as polyamide resin, an elastomer such as rubber, or a reinforcing fiber (for example, glass fiber or carbon fiber) mixed in the synthetic resin or elastomer. The whole is made into a substantially cylindrical shape by the material. The coupling 20 includes a cup side cylindrical portion 33 and a cup side uneven portion 35. The cup-side concavo-convex portion 35 has cup-side

convex portions

34, 34 projecting radially inward at a plurality of locations in the circumferential direction on the inner peripheral surface of the cup-side cylindrical portion 33, and extending in the axial direction. Become.

Each of the cup-side

convex portions

34, 34 constituting the cup-side concavo-convex portion 35 includes a high-tooth height convex portion 36 formed at the axial intermediate portion, and a low-tooth height convex portion 37 a formed at both axial ends. 37b. The tooth height in the radial direction of the low tooth height

convex portions

37 a and 37 b is smaller than the tooth height in the radial direction of the high tooth height convex portion 36. More specifically, the tooth height in the radial direction of the low tooth height

convex portions

37 a and 37 b is about 1/3 to 2/3 of the tooth height in the radial direction of the high tooth height convex portion 36. In addition, the width dimension regarding the circumferential direction of each cup side

convex part

34 and 34 is so small that it goes to radial direction inward (taper shape). In the case of this example, the width dimension in the circumferential direction of each cup-side

convex portion

34, 34 is set to the entire axial direction rather than the width dimension in the circumferential direction of each

convex portion

25, 31 on the driving side and driven side. In other words, it is sufficiently large (for example, about 3 to 7 times).

The tip surfaces (tooth tip surfaces, inner peripheral surfaces) of the other axial end portions of the high tooth height

convex portions

36, 36 constituting the cup side

convex portions

34, 34 are between the drive side

convex portions

25, 25. Are lightly press-fitted into the bottom surface of the half on one side in the axial direction of the drive side recesses 38, 38. That is, at the start of torque transmission between the output shaft 12a and the worm 8a, the tip surfaces of the other end portions in the axial direction of the high tooth height

convex portions

36, 36 and the axial direction of the drive side

concave portions

38, 38 are the same. The bottom surfaces of the side halves are brought into contact with each other with a surface pressure that allows the both surfaces to slide in the circumferential direction.

On the other hand, the tip surfaces of the low tooth height

convex portions

37a, 37a (on the other side in the axial direction) formed at the other axial end portion of the axial end portions of the cup side

convex portions

34, 34, A radial clearance is interposed between the bottoms of the other half portions in the axial direction of the drive side recesses 38 and 38. Moreover, between the front end surface (tooth top surface, outer peripheral surface) of each drive side

convex part

25 and 25, and the bottom face of the cup side recessed

part

41 and 41 which exist between each cup side

convex part

34 and 34 mutually. Has a radial gap over the entire axial width. For this reason, the tooth height in the radial direction of each drive-side

convex portion

25, 25 is made smaller than the tooth height in the radial direction of each high-tooth

convex portion

36, 36. Further, between the driving side uneven part 26 and the other half part in the axial direction of the cup side uneven part 35 (between the driving side facing each other and the circumferential side surfaces of the cup side convex parts 25, 34) in the axial direction A gap in the circumferential direction is interposed over the entire width. In such a state, the driving side uneven portion 26 of the driving side transmission member 22 supported and fixed to the distal end portion of the output shaft 12a (output shaft main body 21) is connected to the other half in the axial direction of the cup side uneven portion 35 of the coupling 20. (The drive-side

convex portions

25, 25 and the cup-side

convex portions

34, 34 are alternately arranged in the circumferential direction in the circumferential direction). .

Moreover, the front end surface of one axial end part of each high tooth height

convex part

36 and 36 is the other axial half part of the driven side recessed

parts

42 and 42 which exist between each driven side

convex part

31 and 31 mutually. Lightly press-fitted into the bottom of the. That is, at the start of torque transmission between the output shaft 12a and the worm 8a, the tip surface of one end portion in the axial direction of each of the high tooth height

convex portions

36, 36, the axial direction of each of the driven side

concave portions

42, 42, etc. The bottom surfaces of the side halves are brought into contact with each other with a surface pressure that allows the both surfaces to slide in the circumferential direction.

On the other hand, the tip surfaces of the low tooth height

convex portions

37b and 37b (on one axial direction side) formed on one axial end portion of the cup-side

convex portions

34 and 34 in the axial direction, A radial clearance is interposed between the drive-side recesses 42 and the bottom surface of one half in the axial direction. In addition, between the front end surface (outer peripheral surface) of each driven-side

convex portion

31, 31 and the bottom surface of one half of the axial direction of each cup-side

concave portion

41, 41, it extends over the entire axial width. A gap is interposed. For this reason, the tooth height in the radial direction of each driven-side

convex portion

31, 31 is made smaller than the tooth height in the radial direction of each high-tooth

convex portion

36, 36. Furthermore, between the driven side uneven part 32 and the axial one side half of the cup side uneven part 35 (between the driven side facing each other and the circumferential side surfaces of the cup side convex parts 31, 34), A gap in the circumferential direction is interposed over the entire axial width. In such a state, the driven-side uneven portion 32 of the driven-side transmission member 28 supported and fixed to the distal end portion of the output shaft 12a (output shaft main body 21) is aligned with the cup-side uneven portion 35 of the coupling 20 in the axial direction. The driven half

convex portions

31 and 31 and the cup side

convex portions

34 and 34 are arranged alternately in the circumferential direction with the side half (the left half in FIG. 1). ing).

The drive side uneven part 26 and the driven side uneven part 32 engaged with the cup side uneven part 35 do not overlap in the axial direction, and are arranged in series in the axial direction. That is, the driving side transmission unit 18 and the driven side transmission unit 19 do not overlap in the axial direction, and are arranged in series in the axial direction.

With the configuration as described above, the driving side transmission unit 18 and the driven side transmission unit 19 are coupled via the coupling 20 so as to be able to transmit torque. In the case of this example, the drive side and driven

side flanges

39 and 40 are engaged with the cup side uneven portion 35 while the drive side and driven side

uneven portions

26 and 32 are engaged with the cup side. By sandwiching the ring 20 (cup side cylindrical portion 33) from both sides in the axial direction (the driving side and driven

side flanges

39 and 40 are brought into contact with or close to both end surfaces in the axial direction of the coupling 20), The coupling 20 is prevented from being excessively displaced in the axial direction.

According to the worm speed reducer 15 of the present example as described above, it is possible to prevent the generation of noise between the output shaft 12a and the worm 8a, and the center axes of the output shaft 12a and the worm 8a are inconsistent with each other. Even in this case, torque transmission between the output shaft 12a and the worm 8a can be performed smoothly.

That is, in the case of this example, the front end surface of the other axial end portion of each high tooth height

convex portion

36, 36 is lightly press-fitted into the bottom surface of one half portion in the axial direction of each driving side

concave portion

38, 38, and each The front end surfaces of the axial end portions of the high tooth

convex portions

36 and 36 are lightly press-fitted into the bottom surfaces of the other half portions in the axial direction of the driven side

concave portions

42 and 42. Therefore, at the start of torque transmission between the output shaft 12a and the worm 8a, the front end surface of the other axial end of each of the high tooth height

convex portions

36, 36 and the axial direction of each of the drive side

concave portions

38, 38 are the same. The bottom half of the side half slides in the circumferential direction, and the circumferential side surface of each drive-side

convex portion

25, 25 abuts (contacts) the circumferential side surface of each cup-side

convex portion

34, 34. Similarly, the tip surface of one axial end portion of each of the high tooth height

convex portions

36, 36 and the bottom surface of the other half portion in the axial direction of the driven-side

concave portions

42, 42 slide in the circumferential direction, and The circumferential side surfaces of the drive-side

convex portions

31 and 31 abut the circumferential side surfaces of the cup-side

convex portions

34 and 34. The momentum of these collisions is weakened by the friction acting between the tip surfaces of the high tooth height

convex portions

36 and 36 and the bottom surfaces of the driving side and driven side

concave portions

38 and 42. For this reason, an unpleasant rattling noise at the abutting portion (contact portion) between the circumferential side surface of each of the

convex portions

25 and 31 on the driving side and the driven side and the circumferential side surface of each cup side

convex portion

34 and 34, etc. The generation of abnormal noise can be prevented.

Further, in the case of this example, between the tip surfaces of the respective low tooth height

convex portions

37a and 37b and the bottom surfaces of the driving side and driven side

concave portions

38 and 42, and the driving side and driven side convex portions 25, A radial gap is interposed between the tip surface of 31 and the bottom surface of each cup-side recess 41. That is, a state in which a radial gap is interposed between the other axial half of the driving side uneven portion 26 and the one axial half of the driven side uneven portion 32 at both axial ends of the cup side uneven portion 35 Are engaged with each other. Further, circumferential clearances are interposed between the drive-side and driven-side

uneven portions

26 and 32 and the cup-side uneven portion 35, respectively. Accordingly, when the worm teeth 6 are pressed toward the tooth portion 5 by the preload applying mechanism 16, the worm 8a swings and the center axes of the output shaft 12a and the worm 8a become inconsistent with each other. The coupling 20 swings based on the presence of the radial gap and the circumferential gap. That is, the coupling 20 uses the abutment portion between the distal end surface of each low tooth height convex portion 37, 37 and the bottom surface of each of the driving side and driven side

concave portions

38, 42 as a fulcrum to support the output shaft 12a and the worm 8a. Tilt with respect to at least one of the axes. Thus, torque can be smoothly transmitted between the output shaft 12a and the worm 8a.

Furthermore, in the case of this example, the tip surfaces of the high tooth height

convex portions

36, 36 formed at the intermediate portions in the axial direction of the cup side

convex portions

34, 34 are the bottom surfaces of the

concave portions

38, 42 on the driving side and the driven side. Therefore, when the torque is transmitted between the output shaft 12a and the worm 8a, the drive-side and driven-side

convex portions

25 and 31 and the cup-side

convex portions

34 and 34 are circumferentially moved ( The rigidity in the direction of rotation) can be improved.

In the case of carrying out this example as described above, a part of the cup-side

convex portions

34, 34 includes a high-tooth height convex portion 36 formed at an axially intermediate portion and both axial end portions. Formed with a low

tooth height portion

37a, 37b whose tooth height in the radial direction is smaller than that of the high tooth height convex portion 36, and the tip surface of the high tooth height convex portion 36 is connected to the drive side, You may lightly press-fit in the bottom face of each recessed

part

38 and 42 to be driven. In this case, the remaining cup side convex portion has a radial direction over the entire axial width of the remaining cup side convex portion between the distal end surface of the remaining cup side convex portion and the bottom surface of each of the driving side and driven side

concave portions

38 and 42. Insert a gap.
Further, the drive-side transmission unit 18 (driven-side transmission unit 19) does not go through the drive-side transmission member 22 (driven-side transmission member 28), but the distal end portion of the output shaft of the electric motor (base end portion of the worm shaft). You may form directly.

[Second Example of Embodiment]
FIG. 6 shows a second example of the embodiment of the present invention. In the case of the torque transmission joint 17a of the present example, the circumferential side widths of the cup-side

convex portions

34a, 34a are the largest in the circumferential direction in the circumferential direction (thick) and are smaller toward the both axial ends. The crowning shape is a partial arc shape whose shape viewed from the radial direction is inclined in a (thin) direction.

In the case of this example, as in the case of the first example of the above-described embodiment, each cup-side

convex portion

34a, 34a is formed with a high tooth height convex portion 36a formed at an axially intermediate portion and a shaft. It is formed of low tooth height convex portions 37c formed at both ends in the direction and having a tooth height in the radial direction smaller than that of the high tooth height convex portion 36a. On the other hand, both side surfaces in the circumferential direction of the drive-side

convex portions

25 and 25 constituting the drive-side concavo-convex portion 26 of the drive-side transmission member 22 are flat surfaces parallel to each other, as in the case of the first example of the above-described embodiment. Yes. That is, the width dimension in the circumferential direction of each drive-side

convex portion

25, 25 is the same over the axial direction. Further, both side surfaces in the circumferential direction of the driven-side

convex portions

31 and 31 constituting the driven-side uneven portion 32 of the driven-side transmission member 28 are flat surfaces parallel to each other. That is, the width dimension of each driven-side

convex portion

31, 31 in the circumferential direction is the same over the axial direction.

Also in the case of this example, similarly to the first example, between the tip surface of each low tooth height convex portion 37c and the bottom surface of each of the driving side and driven side

concave portions

38 and 42, and each driving side convex portion A radial gap is interposed between the tip surfaces of 25 and 31 and the bottom surface of each cup-side recess 41.

In the case of this example as described above, the drive-side uneven portion 26 is engaged with the other half portion in the axial direction of the cup-side uneven portion 35a, and the central axes of the output shaft 12a and the worm 8a (see FIG. 1) Of the drive side

convex portions

25 and 25, the one end in the axial direction of the circumferential side surfaces of the drive side

convex portions

25 and 25 and the circumferential side surfaces of the cup side

convex portions

34a and 34a Touch or close each other. At the same time, the axially intermediate portion of the circumferential side surfaces of the drive-side

convex portions

25, 25 is directed to the other axial side between the other end portion and the circumferential side surface of each of the cup-side

convex portions

34a, 34a. As a result, the

drive side gaps

43, 43 having a larger width dimension in the circumferential direction are interposed.

In addition, the driven-side uneven portion 32 is engaged with one half of the cup-side uneven portion 35a in the axial direction and the center axes of the output shaft 12a and the worm 8a are made to coincide with each other. The other end in the axial direction of the circumferential side surfaces of the

convex portions

31 and 31 and the circumferential side surface of the cup-side

convex portions

34a and 34a abut each other without rattling in the circumferential direction, or face each other. At the same time, the axially intermediate portion of the circumferential side surfaces of each driven-side

convex portion

31, 31 heads toward one axial direction between the one end portion and the circumferential side surface of each cup-side

convex portion

34 a, 34 a. The driven-

side gaps

44 and 44 in which the width dimension in the circumferential direction increases are interposed.

Also in the case of this example as described above, if the center axes of the output shaft 12a and the worm 8a do not coincide with each other, the tip surface of each low tooth height convex portion 37c and the

concave portions

38 and 42 on the driving side and driven side respectively. The radial clearance between the bottom surface, the radial clearance between the tip surface of each drive-side

convex portion

25, 31 and the bottom surface of each cup-side recess 41, and the presence of the drive-side and driven-

side clearances

43, 44. Based on this, the coupling 20a swings. That is, the coupling 20a is inclined with respect to at least one of the output shaft 12a and the worm 8a. Thus, torque can be smoothly transmitted between the output shaft 12a and the worm 8a.

When the structure of this example is implemented, the circumferential side surfaces of the drive-side and driven-side

convex portions

25 and 31 may be crowned shapes in which the shape viewed from the radial direction is a partial arc shape. Moreover, you may make it incline in the direction where the width dimension regarding the circumferential direction of each

convex part

25 and 31 of a drive side and a to-be-driven side becomes small, so that it goes to the width direction (axial direction) both sides of a coupling.
In addition, if grease, which is a lubricant, is interposed in the engaging portion between the driving-side and driven-side

uneven portions

26 and 32 and the cup-side uneven portion 35a, the coupling 20a swings smoothly. In this case, shot blasting is performed on at least one of the circumferential side surfaces of the driving-side and driven-side

convex portions

25 and 31 and the circumferential side surfaces of the cup-side

convex portions

34a and 34a that face each other. It is also possible to provide a large number of minute recesses on at least one surface. If such minute recesses are provided, each of these minute recesses functions as an oil retaining recess for holding grease, so that both the driving side and driven side

uneven portions

26 and 32, the cup side uneven portion 35a, It is possible to easily hold the grease in the engaging portion.
The configuration and operation of the other parts are the same as in the first example of the embodiment described above.

[Third example of embodiment]
FIG. 7 shows a third example of the embodiment of the present invention. In the case of the torque transmission joint 17a of the present example, each drive-side convex portion 25a is formed on the drive-side high-tooth height convex portion 45 formed on one axial half and the other axial half on the other side. Drive-side low tooth height convex portion 46. The drive-side low tooth height convex portion 46 has a smaller tooth height in the radial direction than the drive-side high tooth height convex portion 45. Further, each driven side convex portion 31a has a driven side high tooth height convex portion 47 formed on the other half portion in the axial direction and a driven side low tooth height convex portion formed on the one half portion in the axial direction. 48. The driven-side low tooth height convex portion 48 has a tooth height smaller in the radial direction than the driven-side high tooth height convex portion 47. On the other hand, the tooth height in the radial direction of the cup-side convex portion 34b constituting the cup-side concave / convex portion 35b of the coupling 20b is the same in the axial direction.

In the case of this example, the tip surface of each drive-side high tooth height convex portion 45 is connected to one side portion of the other half in the axial direction of the cup-side concave portion 41a existing between the cup-side convex portions 34b ( Lightly press-fitted into the bottom of the axial middle part). On the other hand, there is a diameter between the distal end surface of each drive-side low tooth height convex portion 46 and the bottom surface of the other side portion (the other end portion in the axial direction) of the other axial half portion of each cup-side concave portion 41a. A directional gap is interposed. Further, between the bottom surface of the drive side recess 38a existing between the drive side protrusions 25a and the tip surface of the other half of the axial side of each cup side protrusion 34b, the entire axial width is reached. A radial gap is interposed. Further, a circumferential clearance is interposed between the drive-side uneven portion 26a and the other half portion in the axial direction of the cup-side uneven portion 35a over the entire axial width. In such a state, the driving side uneven portion 26a of the driving side transmission member 22a is engaged with the other half portion in the axial direction of the cup side uneven portion 35b of the coupling 20b.

Moreover, the front end surface of each driven-side high tooth height convex portion 47 is lightly press-fitted into the bottom surface of the other side portion (axial middle portion) of one cup side concave portion 41a. On the other hand, there is a radial direction between the distal end surface of each drive-side low tooth height convex portion 46 and the bottom surface of one side portion (one axial end portion) of one axial half portion of each cup-side concave portion 41a. A gap is interposed. In addition, the entire width in the axial direction is between the bottom surface of the driven-side concave portion 42a existing between the driven-side convex portions 31a and the front end surface of one half of the axial direction of each cup-side convex portion 34b. In the meantime, a radial gap is interposed. Further, a circumferential clearance is interposed between the driven side uneven portion 26a and the one half portion in the axial direction of the cup side uneven portion 35a over the entire axial width. In such a state, the driven-side uneven portion 32a of the driven-side transmission member 22a is engaged with the one half portion in the axial direction of the cup-side uneven portion 35b of the coupling 20b.

Also in this example, as in the first example of the above-described embodiment, at the start of torque transmission between the output shaft 12a and the worm 8a (see FIG. 1), the driving side and the driven side Due to the friction acting between the tip surface of each high tooth height convex portion 45, 47 and the bottom surface of each cup side concave portion 41a, each of the driving side and driven side

convex portions

25a, 31a and each cup side convex portion 34b The momentum of the abutting between the circumferential side surfaces is reduced, and the generation of abnormal noise at this abutting portion can be prevented.
In the case of this example, the driving side and driven side low tooth height

convex portions

46 and 48 are provided between the front end surface and the bottom surface of each cup side concave portion 41a, and the driving side and driven side concave portions are provided. A radial gap is interposed between the bottom surfaces of 38a and 42a and the tip surface of each cup-side convex portion 34b. At the same time, circumferential gaps are interposed between the drive-side and driven-side

uneven portions

26a and 32a and the cup-side uneven portion 35b. Accordingly, when the central axes of the output shaft 12a and the worm 8a do not coincide with each other, the coupling 20b has a high tooth height on each of the driving side and the driven side based on the existence of the radial gap and the circumferential gap as described above. Inclining with respect to at least one of the output shaft 12a and the worm 8a with the contact portion between the tip surface of the convex portions 45, 47 and the bottom surface of each cup-side concave portion 41a as a fulcrum. Thus, torque can be smoothly transmitted between the output shaft 12a and the worm 8a.
Other configurations and operations are the same as those of the first example of the embodiment.

[Fourth Example of Embodiment]
8 to 11 show a fourth example of the embodiment of the present invention. In the coupling 20 of this example, at least one cup-side protruding portion 49 is formed at the axially intermediate portion of the inner peripheral surface of the cup-side cylindrical portion 33. The cup side protruding portion 49 is formed between the driving side transmission portion 18 and the driven side transmission portion 19 in the axial direction.

In the example of FIG. 8, the cup-side protrusion 49 protrudes radially inward from the cup-side protrusion 34. And the cup side protrusion part 49, the drive side cylindrical part 24, and the to-be-driven side cylindrical part 30 are facing through the clearance gap in the axial direction. However, as in the example of FIG. 9, the cup-side protruding portion 49, the driving-side cylindrical portion 24, and the driven-side cylindrical portion 30 may contact each other without an axial gap.
In the example of FIGS. 8 and 9, one cup-side protrusion 49 is formed on each cup-side protrusion 34. However, at least one cup-side protrusion 49 may be formed. For example, several cup side convex portions 34 may be selected, and the cup side protruding portions 49 may be formed on the selected cup side convex portions 34, respectively.
According to such an example, since at least one cup-side protrusion 49 opposes the driving-side cylindrical portion 24 and the driven-side cylindrical portion 30 in the axial direction, the axial displacement of the coupling 20 is the driving-side cylindrical portion. 24 or the driven cylindrical portion 30.

In the example of FIG. 10, the cup side protrusion 49 protrudes radially inward from the cup side recess 43. The tip end portion (radially inner end portion) of the cup-side protruding portion 49 is located radially inward from the driving side uneven portion 26 and the driven side uneven portion 32. And the cup side protrusion part 49, the driving side convex part 25 and the driven side convex part 31, and the driving side cylindrical part 24 and the driven side cylindrical part 30 are opposed to each other through a gap in the axial direction. However, as in the example of FIG. 11, the cup-side protruding portion 49, the driving-side convex portion 25 and the driven-side convex portion 31, and the driving-side cylindrical portion 24 and the driven-side cylindrical portion 30 have an axial clearance. You may contact | abut without interposition.
In the example of FIGS. 10 and 11, one cup-side protrusion 49 is formed in each cup-side recess 43. However, at least one cup-side protrusion 49 may be formed. For example, several cup-side recesses 43 may be selected, and the cup-side protrusions 49 may be formed in the selected cup-side recesses 43, respectively.
According to such an example, at least one cup-side protrusion 49 faces the driving-side convex portion 25 and the driven-side convex portion 31 and the driving-side cylindrical portion 24 and the driven-side cylindrical portion 30 in the axial direction. The axial displacement of the coupling 20 is regulated by the driving side convex portion 25 and the driven side convex portion 31 and the driving side cylindrical portion 24 or the driven side cylindrical portion 30.

The example of FIG. 12 is the same as the example of FIG. 10 in that the cup side protrusion 49 protrudes radially inward from the cup side recess 43. However, the example of FIG. 12 is different from the example of FIG. 10 in that the tip end portion (radially inner end portion) of the cup-side protrusion 49 overlaps the driving-side uneven portion 26 and the driven-side uneven portion 32 in the radial direction. . In the example of FIG. 12, the cup-side protruding portion 49, the driving-side convex portion 25, and the driven-side convex portion 31 face each other with a gap in the axial direction. However, as in the example of FIG. 13, the cup-side protruding portion 49, the driving-side convex portion 25, and the driven-side convex portion 31 may contact each other without an axial gap.
In the example of FIGS. 12 and 13, one cup-side protrusion 49 is formed in each cup-side recess 43. However, at least one cup-side protrusion 49 may be formed. For example, several cup-side recesses 43 may be selected, and the cup-side protrusions 49 may be formed in the selected cup-side recesses 43, respectively.
According to such an example, since at least one cup-side protrusion 49 opposes the driving-side protrusion 25 and the driven-side protrusion 31 in the axial direction, the axial displacement of the coupling 20 causes the driving-side protrusion. 25 and the driven-side convex portion 31.

It should be noted that the coupling 20 may be configured by combining a plurality of types of cup-side protrusions 49 shown in FIGS. For example, in one coupling 20, the cup-side protrusion 49 of FIG. 8 may be formed in the cup-side protrusion 34, and the cup-side protrusion 49 of FIG. 10 may be formed in the cup-side recess 43.

According to this example, the cup-side cylindrical portion 33 is formed with an annular cup-side protruding portion 49 between the drive-side transmission portion 18 and the driven-side transmission portion 19 in the axial direction on the inner peripheral surface of the cup-side cylindrical portion 33. The axial displacement of the ring 20 is regulated by the driving side transmission unit 18 or the driven side transmission unit 19, and the axial position of the coupling 20 is stabilized. Therefore, the axial displacement of the coupling 20 can be restricted without providing both the driving side and driven side flanges 39 and 40 (see FIG. 2). When the driving side and driven

side flanges

39 and 40 are not provided, it is possible to reduce the weight of the component and reduce the cost. 8 to 13, the drive side and driven

side flanges

39 and 40 are not provided. However, in order to further stabilize the axial position of the coupling 20, the cup side protruding portion 49 is not provided. In addition, both the driving side and driven

side flanges

39 and 40 may be provided.

In addition, what is necessary is just to also provide the said cup side protrusion part in the outer peripheral surface of a coupling, when a coupling side uneven | corrugated | grooved part is provided in the outer peripheral surface of a coupling.
[Fifth Example of Embodiment]
14 and 15 show a fifth example of the embodiment of the present invention. In the coupling 20 of this example, an annular cored bar 50 is disposed inside the cup-side cylindrical portion 33 as a whole. The core metal 50 includes a cylindrical portion 51 concentric with the coupling 20. The cylindrical part 51 overlaps at least the engaging part of the driving side uneven part 26 and the driven side uneven part 32 and the cup side uneven part 35 in the axial direction. In the example of FIG. 14, the axial length of the cylindrical portion 51 is about three-quarters of the axial length of the coupling 20, but may be the same as the axial length of the coupling 20.

As shown in FIG. 15, the core metal 50 may include a plurality of convex portions 52 that protrude radially inward from the inner peripheral surface of the cylindrical portion 51 at equal intervals in the circumferential direction. The same number of the plurality of convex portions 52 is provided at a position overlapping the plurality of cup-side convex portions 34 of the coupling 20 in the circumferential direction. The plurality of convex portions 52 may not be the same as the plurality of cup-side convex portions 34. The circumferential length of the convex portion 52 is equal to or less than the circumferential length of the cup-side convex portion 34.

According to this example, since the cored bar 50 is disposed inside the coupling 20, the rigidity of the coupling 20 can be improved. In particular, the cored bar 50 overlaps at least the engagement portion of the driving side uneven portion 26 and the driven side uneven portion 32 and the cup side uneven portion 35 in the axial direction, so that the rigidity of the coupling 20 is improved against rotational torque. The effect of can be enhanced. Furthermore, when the plurality of convex portions 52 are provided on the core metal 50, the rigidity of the coupling 20 is further improved.

[Sixth Example of Embodiment]
16 and 17 show a sixth example of the embodiment of the present invention. Also in the coupling 20 of this example, the cored bar 50 is disposed inside the cup-side cylindrical portion 33 as in the fifth example. However, the core metal 50 of this example is configured by rounding a wire net-like sheet or a chain-like metal member as shown in FIG. 17 into a cylindrical shape.

According to this example, as in the fifth example, in addition to improving the rigidity of the coupling 20, the coupling 20 is easy to bend, so that when the worm 8a swings, the coupling 20 swings more flexibly. This facilitates torque transmission between the output shaft 12a and the worm 8a.

This application is based on Japanese Patent Application No. 2015-092091 filed on April 28, 2015, the contents of which are incorporated herein by reference.

When carrying out the present invention, the drive side uneven 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 the inner peripheral surface of the concave portion provided at the proximal end portion of the worm shaft. It is also possible to form a driven-side concavo-convex portion so that a coupling-side concavo-convex portion provided on the outer peripheral surface of the coupling is engaged with the driving-side concavo-convex portion and the driven-side concavo-convex portion.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Housing 4 Worm wheel 5 Tooth part 6 Worm tooth 7 Electric motor 8, 8a Worm 9a, 9b Rolling bearing 10 Pressing piece 11 Coil spring 12, 12a Output shaft 13 Spline hole 14 Spline shaft part 15 Warm deceleration Machine 16 Preload applying mechanism 17, 17a Torque transmission joint 18 Drive side transmission part 19 Driven side transmission part 20, 20a, 20b Coupling 21 Output shaft body 22, 22a Drive side transmission member 23 Drive side engagement hole 24 Drive side Cylindrical portion 25, 25a Drive-side convex portion 26, 26a Drive-side uneven portion 27 Worm shaft body 28, 28a Drive-side transmission member 29 Drive-side engagement hole 30 Drive-side cylindrical portion 31, 31a Drive-side convex portion 32 , 32a Driven side uneven part 33 Side cylindrical portion 34, 34a, 34b Cup side convex portion 35, 35a, 35b Cup side concave portion 36, 36a High tooth height convex portion 37a to 37c Low tooth height convex portion 38, 38a Drive side concave portion 39 Drive side flange portion 40 Covered Drive side collar 41, 41a Cup side recess 42, 42a Driven side recess 43 Drive side clearance 44 Driven side clearance 45 Drive side high tooth height convex portion 46 Drive side low tooth height convex portion 47 Drive side high tooth height convexity Part 48 driven side low tooth height convex part 49 cup side protruding part 50 cored bar 51 cylindrical part 52 convex part

Claims

A torque transmission joint that transmits torque between one axial end of the drive shaft and the other axial end of the driven shaft, arranged in series with respect to the axial direction,
A coupling provided with cup-side irregularities on one circumferential surface of the inner and outer circumferential surfaces, the cup-side convex portions protruding in the radial direction being arranged at a plurality of locations in the circumferential direction,
Provided at one end in the axial direction of the drive shaft, and on the inner and outer peripheral surfaces facing the cup-side concavo-convex portion, drive-side convex portions protruding in the radial direction are arranged at a plurality of locations in the circumferential direction. A drive-side transmission portion provided with a drive-side uneven portion;
Provided at the other end in the axial direction of the driven shaft, among the inner and outer peripheral surfaces, the driven-side convex portions protruding in the radial direction are arranged at a plurality of locations in the circumferential direction on the peripheral surface facing the cup-side uneven portion. A driven side transmission portion provided with a driven side uneven portion,
With
Engage the driving-side uneven portion with the other axial half of the cup-side uneven portion, and engage the driven-side uneven portion with the axial one-side half of the cup-side uneven portion. And
One of the drive-side protrusions and the cup-side protrusions in one axial half of the engagement portion between the drive-side unevenness and the other axial half of the cup-side unevenness. Lightly press-fit the front end surface of the first convex portion that is the convex portion of the first convex portion into the bottom surface of the first concave portion that exists between the second convex portions that are the other convex portions, and the drive side uneven portion and the cup side uneven portion The front end surface of the first convex portion is opposed to the bottom surface of the first concave portion via a radial gap in the other axial half portion of the engaging portion with the other axial half portion of the portion, and the drive A circumferential gap is interposed between the side uneven portion and the cup side uneven portion,
Of the driven side convex portions and the cup side convex portions, the other half portion in the axial direction of the engaging portion between the driven side concave and convex portion and the axial one side half of the cup side concave and convex portion. Lightly press-fitting the tip surface of the third convex portion that is one of the convex portions into the bottom surface of the second concave portion that exists between the fourth convex portions that are the other convex portions, and the driven side uneven portion and the While the axially one side half of the engaging part is in contact with the axially one side half of the cup-side concavo-convex part, the tip surface of the third convex part is opposed to the bottom surface of the second concave part via a radial gap. In addition, a circumferential clearance is interposed between the driven side uneven portion and the cup side uneven portion,
Joint for torque transmission.
Each cup-side convex portion has a high tooth height convex portion formed at an axially intermediate portion and a tooth height in the radial direction smaller than the high tooth height convex portion formed at both axial end portions. It consists of tooth height convex part,
Lightly press-fitting the front end surface of the other axial end of the high tooth height convex portion into the bottom surface of the driving side concave portion existing between the driving side convex portions, and the axial end portions of the cup side convex portions. The front end surface of the low tooth height convex portion formed at the other axial end portion is opposed to the bottom surface of the driving side concave portion via a radial gap,
Lightly press-fitting the tip end surface of one end in the axial direction of the high-tooth convex portion into the bottom surface of the driven-side concave portion existing between the driven-side convex portions, and both axial ends of the cup-side convex portions The tip surface of the low tooth height convex portion formed at one axial end portion of the portion is opposed to the bottom surface of each driven-side concave portion via a radial gap,
The joint for torque transmission according to claim 1.
The drive-side convex portions are formed on the drive-side high-tooth height convex portion formed on the one-side half portion in the axial direction and the drive-side high-tooth height convex portion formed on the other half portion in the axial direction. It consists of a drive-side low tooth height convex part with a small tooth height,
Each driven-side convex portion includes a driven-side high tooth height convex portion formed in the other half portion in the axial direction and the driven-side high tooth height convex portion formed in the one half portion in the axial direction. Is also composed of a driven side low tooth height convex part with a small tooth height in the radial direction,
Lightly press-fitting the front end surface of the driving side high tooth height convex portion into the bottom surface of the cup side concave portion existing between the cup side convex portions, and the driving side low tooth height convex portion of the cup side concave portion. It faces the bottom via a radial gap,
Lightly press-fitting the front end surface of the driven-side high tooth height convex portion into the bottom surface of the cup-side concave portion, and oppose the driven-side low tooth height convex portion to the bottom surface of the cup-side concave portion via a radial gap. Let
The joint for torque transmission according to claim 1.
A circumferential side surface of each drive-side convex portion in a state where the drive-side uneven portion is aligned with the other axial half of the cup-side uneven portion, and the center axes of the drive shaft and the driven shaft are aligned with each other. And a gap on the drive side where the width dimension in the circumferential direction increases toward the other side in the axial direction between the cup side convex portion and the side surface in the circumferential direction of each cup side convex portion.
In the state where the driven-side concavo-convex part is aligned with one axial half of the cup-side concavo-convex part and the central axes of the drive shaft and the driven shaft are aligned, the circumference of each driven-side convex part Engaged with a driven side gap in which the width dimension in the circumferential direction increases toward the one side in the axial direction between the direction side surface and the circumferential side surface of each cup-side convex portion,
The torque transmission joint according to any one of claims 1 to 3.
A crowning shape in which the circumferential side surface of each cup-side convex portion is inclined in a direction in which the width dimension in the circumferential direction of each cup-side convex portion is the largest in the axial middle portion and decreases toward the both axial end portions. The joint for torque transmission according to claim 4.
One of the inner and outer peripheral surfaces of the coupling is formed with a cup-side protrusion that protrudes in the radial direction,
The joint for torque transmission according to any one of claims 1 to 5, wherein the cup-side protruding portion is located between the drive-side transmission portion and the driven-side transmission portion in the axial direction.
A housing;
A worm wheel rotatably supported with respect to the housing;
A worm rotatably supported with respect to the housing in a state where a worm tooth provided in an axially intermediate portion is engaged with the worm wheel;
An electric motor for rotationally driving the worm;
With
The worm and the output shaft of the electric motor are connected so as to be able to transmit torque by a torque transmission joint.
In the worm reducer,
A worm reduction gear, wherein the torque transmission joint is the torque transmission joint according to any one of claims 1 to 6.