JP5077124B2 - Torque transmission joint and electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce cost in an electric power steering device, by realizing an elastic shock absorbing member for freely adjusting the size of resiliency and a shape in response to the size of torque transmitted by a spline engaging part and a shape of an installation space. <P>SOLUTION: The elastic shock absorbing member is formed as an elastic ring assembly 23 constituted by densely gathering a plurality of elastic rings 24 and 24 having the same item. The number and arrangement of the respective elastic rings 24 and 24 for constituting this elastic ring assembly 23, are properly changed in response to the size of the torque transmitted by the spline engaging part and a shape and the size of an annular clearance 17c being the installation space of the elastic ring assembly 23. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The electric power steering device of the torque transmission joint and the electric power steering device that are the subject of the present invention is used as a steering device of an automobile. By using an electric motor as an auxiliary power source, a driver is used. Reduces the force required to operate the steering wheel. In addition, the torque transmission joint is incorporated in the torque transmission section between the output shaft of the electric motor and the worm shaft of the speed reducer constituting such an electric power steering device, for example, so that rattling noise is generated during steering. The auxiliary power is transmitted from the output shaft to the worm shaft while being suppressed.

  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. Also, in such a power steering device, an electric power steering device using an electric motor as an auxiliary power source has been widely implemented. The electric power steering device can be made smaller and lighter than the hydraulic power steering device, has advantages such as easy control of the magnitude (torque) of auxiliary power and less power loss of the engine.

  Various structures of the electric power steering apparatus are known. In any structure, the steering wheel is rotated by the operation of the steering wheel, and the steering rotation shaft that gives the steering wheel with the rotation is electrically operated. Auxiliary power of the motor is applied through a reduction gear. In general, a worm reducer is used as the reducer. In the case of an electric power steering apparatus using a worm speed reducer, a worm that is rotationally driven by the electric motor and a worm wheel that rotates together with the steering rotating shaft are engaged with each other, and the auxiliary power of the electric motor is steered by the steering. It can be transmitted to the rotating shaft. However, in the case of a worm speed reducer, if no measures are taken, a rattling sound is generated when the rotation direction of the steering rotation shaft is changed based on the backlash existing in the meshing portion of the worm and the worm wheel. An unpleasant noise called may occur.

  Conventionally, as described in Patent Documents 1 to 3, it is considered that the worm is elastically pressed toward the worm wheel by an elastic member such as a spring as a structure that can suppress the generation of such rattling noise. ing. 6 to 7 show an example of the electric power steering device described in Patent Document 2 among them. A front end portion of a steering shaft 2 that is a steering rotation shaft 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 meshing with the worm wheel 4 are provided in the axial direction intermediate portion of the worm shaft 6, and both ends of the worm 8 driven to rotate by the electric motor 7 are paired with a pair of rolling bearings 9 a such as a deep groove ball bearing, 9b is rotatably supported in the housing 3. 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. ing. The coil spring 11 presses the worm teeth 5 provided on the worm shaft 6 toward the worm wheel 4 through the pressing piece 10. With such a configuration, backlash between the worm teeth 5 and the worm wheel 4 is suppressed, and generation of the rattling noise is suppressed. As the backlash is eliminated, the central axis of the worm shaft 6 and the central axis of the output shaft 12 of the electric motor 7 do not exactly coincide with each other. However, the deviation between these central axes is very small, and the worm shaft 6 and the output shaft 12 remain substantially concentric.

  In the case of the conventional structure as described above, it is possible to suppress the occurrence of the rattling noise at the meshing portion between the worm tooth 5 and the worm wheel 4, but the tip of the output shaft 12 and the base of the worm shaft 6 can be suppressed. It is not possible to suppress the rattling noise generated at the connection with the end. This point will be described below. In order to connect the distal end portion of the output shaft 12 of the electric motor 7 and the proximal end portion of the worm shaft 6 so as to be able to freely transmit the rotational force, a spline hole 13 is formed at the proximal end portion of the worm shaft 6. It forms in the state opened to the base end surface of the axis | shaft 6. FIG. A spline shaft portion 14 is formed at the tip of the output shaft 12. Then, the spline shaft portion 14 and the spline hole 13 are spline-engaged to constitute a torque transmission joint 15, and the output shaft 12 and the worm shaft 6 can be freely connected to transmit torque. ing. The “spline” in the present specification and claims includes what is called “serration” with a fine pitch.

  If the spline shaft portion 14 and the spline hole 13 are in spline engagement with no circumferential clearance (without backlash), the distal end portion of the output shaft 12 and the proximal end portion of the worm shaft 6 No rattling noise is generated at the connecting part (spline engaging part). However, in the actual case, a backlash exists in the spline engaging portion. The backlash of the spline engaging portion is necessary for facilitating the work of spline engaging the spline shaft portion 14 and the spline hole 13. Further, as long as the center axis of the output shaft 12 and the center axis of the worm shaft 6 are slightly deviated from each other, it is necessary to rotate the output shaft 12 so that the spline engaging portion is not distorted. The backlash is also necessary to prevent the torque from increasing. In particular, a structure that eliminates backlash between the worm teeth 5 and the worm wheel 4 by pressing the worm teeth 5 provided on the worm shaft 6 against the worm wheel 4 by an elastic member such as the coil spring 11. In this case, it is essential to provide a backlash for the spline engaging portion.

  However, when there is backlash in the spline engaging portion, at the moment when the rotation direction of the electric motor 7 is changed, the circumferential side surface of the male spline teeth provided on the outer peripheral surface of the spline shaft portion 14; The circumferential side surface of the female spline tooth provided on the inner peripheral surface of the spline hole 13 collides with vigor, and the rattling noise is generated. Such a rattling noise becomes more prominent as the backlash of the spline engaging portion becomes larger. Conventionally, this backlash is within the range in which the spline engaging portion can be assembled, and further, the worm The backlash between the teeth 5 and the worm wheel 4 is reduced to the extent that the backlash can be eliminated. However, if the backlash of the spline engaging portion is reduced, the spline shaft portion 14 is less likely to be inserted into the spline hole 13 and the assembling workability is reduced, which increases the manufacturing cost of the electric power steering device. Cause. Further, unless the assembly accuracy between the output shaft 12 and the worm shaft 6 is increased, the problem of the torque increase due to the galling is likely to occur, which also increases the manufacturing cost of the electric power steering apparatus.

  In view of such circumstances, for example, in Patent Documents 4 and 5, an elastic buffer member such as an O-ring is provided in an elastically compressed state between the outer peripheral surface of the spline shaft portion and the inner peripheral surface of the spline hole. Thus, an invention for preventing occurrence of rattling noise at the spline engaging portion is described. FIG. 8 shows a torque transmission joint 15a described in Patent Document 4 among them. In the case of this torque transmission joint 15a, a concave groove-like locking groove 16 is formed over the entire circumference on a part of the outer peripheral surface of the spline shaft portion 14a. And the elastic ring 18 which is an elastic buffer member is incorporated in the annular clearance 17 provided between this latching groove | channel 16 and the internal peripheral surface of the spline hole 13 in the state compressed elastically. Thus, the inner and outer peripheral edges of the elastic ring 18 are frictionally engaged with the outer peripheral surface of the locking groove 16 and the inner peripheral surface of the spline hole 13, respectively, so that the spline shaft portion 14 a and the spline hole 13 are engaged. The relative displacement speed in the torque transmission direction is suppressed, and the occurrence of the rattling noise is suppressed.

  Further, in the case of the torque transmission joint 15b described in Patent Document 5, as shown in FIG. 9, a pair of locking grooves is formed on the outer peripheral surface of the spline shaft portion 14b in the axially separated state. 16a and 16b are formed. The elastic rings 18a and 18b are elastically compressed in a pair of annular gaps 17a and 17b provided between the locking grooves 16a and 16b and the inner peripheral surface of the spline hole 13, respectively. It is incorporated in. Thereby, generation | occurrence | production of a rattling sound is suppressed similarly to the case of the structure described in the patent document 4 mentioned above.

  By the way, as described above, when the elastic buffer member is used to suppress the occurrence of rattling noise, the magnitude of elasticity required for the elastic buffer member is between the output shaft of the electric motor and the worm shaft ( Depending on the magnitude of the torque transmitted by the spline engaging portion). For this reason, in the case of the conventional structures described in Patent Documents 4 and 5 described above, it is necessary to use an elastic ring having elasticity corresponding to the magnitude of torque transmitted by the spline engaging portion. . Furthermore, it is necessary to use an elastic ring that matches the shape (cross-sectional shape) and size of the annular gap, which is the installation space for the elastic ring. Therefore, in the case of the conventional structures described in Patent Documents 4 and 5, if the magnitude of the torque transmitted by the spline engaging portion or the shape / size of the annular gap is different, it has been used until then. Therefore, it is difficult to prevent the occurrence of rattling noise by using the elastic ring as it is, so that a different type of elastic ring is newly required. For this reason, the cost for obtaining an elastic ring suitable for preventing the occurrence of rattling noise increases, which causes an increase in cost of the electric power steering apparatus.

JP 2000-43739 A JP 2004-306898 A JP-T-2006-513906 JP 2003-34256 A JP 2004-122852 A

  In view of the circumstances as described above, the present invention realizes an elastic cushioning member capable of adjusting the magnitude and shape of elasticity according to the magnitude of torque transmitted by the spline engaging portion and the shape of the installation space. The present invention has been invented to reduce the cost of the structure that can suppress the occurrence of rattling noise at the spline engaging portion.

Of the torque transmission joint and the electric power steering apparatus according to the present invention, the torque transmission joint according to the first aspect is provided between ends of a pair of rotating shafts arranged in series with respect to the axial direction. For transmitting torque with a spline hole and a spline shaft.
Of these, the spline hole is provided so as to open to the end surface of one of the two rotating shafts, and forms a female spline portion on the inner peripheral surface.
The spline shaft portion is provided at the end of the other rotation shaft of the two rotation shafts, and forms a male spline portion on the outer peripheral surface.
The spline hole and the spline shaft portion are spline-engaged so that torque can be transmitted between the rotary shafts.
Further, an elastic buffer member is provided between the inner peripheral surface of the spline hole and the outer peripheral surface of the spline shaft portion in a state of being elastically compressed between the two peripheral surfaces.
In particular, in the torque transmission joint according to the present invention, the elastic buffer member is formed by aggregating a plurality of elastic rings in a radial direction . Preferably, those elastic rings having the same specifications are used.

When the above-described torque transmission joint according to the present invention is implemented, for example, as in the invention described in claim 2, the spline shaft portion is disengaged in the axial direction from the male spline portion in the outer peripheral surface of the spline shaft portion. A concave groove-like locking groove is formed in the part over the entire circumference. Thus, an annular annular gap having a constant radial dimension over the entire circumference is formed between the locking groove and the inner peripheral surface of the spline hole, and the elastic buffer member is placed in the annular gap. Provide.
Further, the electric power steering apparatus according to the third aspect is similar to the above-described conventionally known electric power steering apparatus, and includes a housing, a rotating shaft for steering, a worm wheel, a worm, and an electric motor. A motor.
Of these, the housing is supported by a fixed part such as a vehicle body and does not rotate during steering.
The steering rotation shaft is rotatably provided with respect to the housing, and is rotated by an operation of a steering wheel, and gives a steering angle to the steered wheels as it rotates. As such a rotating shaft for steering, any shaft that moves in synchronization with the steering wheel and the steering wheel can be employed. For example, the input shaft (pinion shaft) of the steering shaft 2 or the intermediate shaft 19 as well as the steering gear unit 20 in the structure shown in FIG.
The worm wheel is supported on a part of the steering rotation shaft inside the housing, concentrically with the steering rotation shaft, and rotates together with the steering rotation shaft.
The worm is formed by providing a worm tooth at an intermediate portion of the worm shaft in the axial direction. With the worm tooth engaged with the worm wheel, both end portions of the worm shaft in the axial direction are respectively attached to the housing by bearings. It is supported so that it can rotate freely.
The electric motor is 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 as to be able to transmit torque.
In particular, in the electric power steering apparatus of the present invention, the torque transmission joint is the torque transmission joint according to any one of claims 1 and 2 .

In the case of the torque transmission joint and the electric power steering apparatus according to the present invention having the above-described configuration, the elastic buffer member is configured by assembling a plurality of elastic rings. By changing the number of elastic rings according to the magnitude of torque transmitted between the output shaft and the worm shaft, it is possible to easily obtain the elasticity necessary to suppress the generation of rattling noise.
Further, in the case of the present invention, the number and arrangement (arrangement) of the elastic rings constituting the elastic buffer member can be changed in accordance with the installation space for installing the elastic buffer member.
Therefore, in the case of the present invention, there is no need for a new type of elastic buffer member according to the magnitude of the torque transmitted by the spline engaging portion and the shape / size of the installation space. By appropriately changing the number and arrangement of the elastic rings constituting the buffer member, it is possible to easily obtain an elastic buffer member suitable for preventing the occurrence of rattling noise.
In the case of the present invention, since the elastic buffer member can be constituted by an elastic ring having the same specifications, the cost of the elastic buffer member can be reduced.
Thus, in the case of the present invention, an elastic cushioning member suitable for preventing the occurrence of rattling noise can be easily obtained regardless of the magnitude of torque transmitted by the spline engaging portion and the shape / size of the installation space. And it can be obtained at low cost. For this reason, the cost reduction of the structure which can suppress generation | occurrence | production of the rattling sound in the said spline engaging part can be achieved.

  1 to 5 show an example of an embodiment of the present invention. The feature of the electric power steering device of this example is the structure of a torque transmission joint 15c provided at the connection between the distal end portion of the output shaft 12 of the electric motor 7 and the proximal end portion of the worm shaft 6. . In addition, since the structure and operation of the entire electric power steering apparatus are the same as those of a widely implemented conventional structure, illustrations and explanations relating to parts equivalent to the conventional structure are omitted or simplified. The description will focus on the features of the example. 6 to 7 and FIG. 1 are different in the mounting direction of the electric motor 7 with respect to the housing 3, but this point is appropriately changed in design according to the vehicle to be installed. It has nothing to do with the features of the example.

  In the case of the structure of this example, as shown in FIGS. 1 to 4, a female spline portion is formed on the inner peripheral surface of the base end portion (the right end portion of FIGS. Is formed concentrically with the worm shaft 6 in a state where the spline hole 13 is opened on the base end surface of the worm shaft 6. A spline shaft portion 14c having a male spline portion formed on the outer peripheral surface is formed concentrically with the output shaft 12 at the tip end portion (left end portion in FIGS. 1 to 4) of the output shaft 12. The spline shaft portion 14c and the spline hole 13 are spline-engaged so that the output shaft 12 and the worm shaft 6 are coupled so as to be able to transmit a rotational force, thereby forming a torque transmission joint 15c. doing.

  In the case of this example, the pitch circle diameter of the female spline teeth 21 and 21 constituting the inner peripheral surface of the spline hole 13 is set as the male spline teeth 22 constituting the outer peripheral surface of the spline shaft portion 14c. The spline shaft portion 14c is slightly larger than the pitch circle diameter of 22 so that the spline shaft portion 14c can be loosely inserted into the spline hole 13. Therefore, in the spline engaging portion between the spline shaft portion 14c and the spline hole 13, the tip portion of the worm shaft 6 (in FIG. There is sufficient backlash to displace the left end) towards the worm wheel 4. In other words, with the elimination of backlash at the meshing portion between the worm teeth 5 and the worm wheel 4, inconveniences such as galling are less likely to occur at the spline engagement portion.

  Further, in the case of this example, a concave groove-like engagement is formed on the outer circumferential surface of the spline shaft portion 14c at a portion (right portion in FIGS. The stop groove 16c is formed over the entire circumference. Thereby, an annular annular gap 17 c is formed between the locking groove 16 c and the inner peripheral surface of the spline hole 13.

  In the case of this example, the elastic ring assembly 23 that is an elastic buffer member is incorporated in the annular gap 17c in an elastically compressed state. The elastic ring assembly 23 is formed by densely collecting a plurality of elastic rings 24 and 24 having the same specifications (in a state where the respective surfaces are in contact with each other). The number and arrangement of the elastic rings 24, 24 can be changed as appropriate according to the magnitude of torque to be transmitted and the shape and size of the annular gap 17c.

  Specifically, as shown in FIGS. 1 and 2, the elastic ring assembly 23 can be composed of three elastic rings 24 and 24, or as shown in FIG. The elastic ring assembly 23 may be composed of four elastic rings 24 and 24. In this way, the structure using the four elastic rings 24, 24 is transmitted from the output shaft 12 of the electric motor 7 to the worm shaft 6 as compared with the structure using the three elastic rings 24, 24. This is performed when the torque to be applied is large. Furthermore, as shown in FIG. 3B, the elastic ring assembly 23 can be composed of five elastic rings 24 and 24. On the other hand, when the transmitted torque is small, the elastic ring assembly 23 can be composed of two elastic rings 24 and 24 as shown in FIG.

That is, the torque is small and the radial dimension of the annular gap 17c (the outer peripheral surface of the locking groove 16c and the inner peripheral surface of the spline hole 13 is smaller than that in the structure shown in FIGS. When the dimension between them is small, as shown in FIG. 4A , which is shown as a reference example , the two elastic rings 24 and 24 may be arranged in the axial direction in the annular gap 17c. it can. Also, when the axial dimension of the annular gap 17c is smaller than that of the structure shown in FIGS. 1 to 3, the annular gap 17c includes 2 in the annular gap 17c as shown in FIG. It is also possible to arrange the elastic rings 24, 24 so as to overlap each other in the radial direction.

The elastic rings 24 and 24 constituting the elastic ring assembly 23 are standard O-rings having high versatility and are made of an elastic material such as an elastomer such as rubber and have the same shape. Specifically, as shown in FIG. 5, each elastic ring 24 has an annular shape as a whole and a substantially circular cross-sectional shape in a free state. The wire diameter d in the free state is constant over the entire circumference, and has a size that allows at least two wires to be arranged in the annular gap 17c in an elastically compressed state. For this reason, in the case of this example, the elastic force of each of the elastic rings 24, 24 is set in a single elastic ring 18, 18 a, 18 b (see FIGS. 8 and 9) in the annular gap 17 c. Is smaller than the elasticity of each of the elastic rings 18, 18a, 18b. The wire diameter d is preferably as small as possible within a range in which the assembly work described later is not troublesome so that the elastic ring assembly 23 can be finely adjusted in size and shape. The inner diameter r of each elastic ring 24 in the free state is slightly smaller than the groove bottom diameter R (see FIG. 2) of the locking groove 16c (r <R).

The operation of assembling the elastic ring assembly 23 as described above into the annular gap 17c is performed as follows. In the following description, the elastic ring assembly 23 composed of the three elastic rings 24 and 24 shown in FIGS. First, the two elastic rings 24, 24 constituting the elastic ring assembly 23 are fitted on the outer peripheral surface of the locking groove 16c by interference fitting. Next, the other elastic ring 24 is fitted on the outer peripheral surface of these two elastic rings 24, 24 (in a state of straddling between the outer peripheral surfaces) by an interference fit . The elastic rings 24, 24 and one elastic ring 24 on the outer diameter side are overlapped in the radial direction. In this way, when the elastic ring assembly 23 is mounted in the locking groove 16c, the elastic ring assembly 23 (elastic rings 24, 24) is compressed (crushed) from the outer diameter side, The spline shaft portion 14c is inserted into the spline hole 13 (spline engagement).

  With the elastic ring assembly 23 assembled in the annular gap 17c as described above, the elastic rings 24 and 24 constituting the elastic ring assembly 23 are elastically crushed. Each produces elasticity according to the amount of compression. Thus, in the case of the structure shown in FIGS. 1 and 2, the inner surface of the two elastic rings 24, 24 arranged on the outer peripheral surface of the locking groove 16 c and the inner diameter side of the elastic ring assembly 23. The peripheral edge is frictionally engaged, and the inner peripheral surface of the spline hole 13 and the outer peripheral edge of one elastic ring 24 arranged on the outer diameter side of the elastic ring assembly 23 are frictionally engaged. Furthermore, the outer peripheral edges of the two elastic rings 24, 24 arranged on the inner diameter side and the inner peripheral edge of the one elastic ring 24 arranged on the outer diameter side are frictionally engaged. 3 and 4, in the assembled state, both the inner and outer peripheral edges of the elastic rings 24, 24, the outer peripheral face of the locking groove 16c, and the inner peripheral face of the spline hole 13 in the assembled state. Are each frictionally engaged. In any of the cases shown in FIGS. 1 to 4, the elastic ring assembly 23 has a state of elasticity corresponding to the number of the elastic rings 24, 24.

  In the case of this example having the above-described configuration, the circumferential side surfaces of the female and male spline teeth 21 and 22 tend to collide vigorously with the conversion of the rotation direction of the electric motor 7 and the like. In this case, the elastic ring assembly 23 has sufficient resistance against the force to be collided (the force with which the output shaft 12 and the worm shaft 6 are relatively displaced in the torque transmission direction). Demonstrate (exhibits buffering effect). That is, even if the circumferential side surfaces of the female and male spline teeth 21 and 22 tend to collide with each other with vigor, the elastic ring assembly 23 can attenuate the momentum and suppress the collision. As a result, in this example, the backlash of the spline engaging portion between the spline shaft portion 14c and the spline hole 13 is secured to some extent, and rattling noise is generated at the spline engaging portion. Things can be suppressed enough.

  In addition, in the case of this example, as described above, each of the elastic ring aggregates 23 that constitute the elastic ring assembly 23 according to the magnitude of torque transmitted from the output shaft 12 of the electric motor 7 to the worm shaft 6. Since the number of the elastic rings 24, 24 can be changed, it is possible to easily obtain an appropriate elasticity for suppressing the occurrence of the rattling noise. Furthermore, in the case of this example, the number and arrangement (arrangement) of the elastic rings 24 and 24 can be changed according to the shape (cross-sectional shape) and size of the annular gap 17. Therefore, in the case of this example, according to the conventional structure described in Patent Documents 4 and 5 described above, depending on the magnitude of torque transmitted by the spline engaging portion and the shape and size of the annular gap 17c. In this way, different types of elastic rings 18, 18a, 18b (see FIGS. 8 and 9) are not newly required, and by changing the number and arrangement of the elastic rings 24, 24, the rattling can be achieved. The elastic ring assembly 23 suitable for preventing the generation of sound can be easily obtained. In the case of this example, since the elastic ring assembly 23 is composed of elastic rings 24 and 24 having the same specifications, the elastic rings 18, 18a and 18b are newly designed and manufactured. In comparison with the above, the cost for obtaining the elastic ring assembly 23 can be reduced. Thus, in the case of this example, the elastic ring assembly 23 suitable for preventing the occurrence of rattling noise is obtained regardless of the magnitude of the torque transmitted by the spline engaging portion and the shape / size of the installation space. Since the torque transmission joint 15c having such an elastic ring assembly 23 and the torque transmission joint 15c are incorporated, the electric power steering apparatus according to this embodiment is low in cost and can be easily obtained at low cost. Cost can be reduced.

  When carrying out the present invention, the number of elastic rings constituting the elastic ring assembly is not limited to the above-described embodiment, and torque transmitted between the output shaft of the electric motor and the worm shaft. It can be appropriately changed according to the size and installation space. The cross-sectional shape of each elastic ring in the free state is not limited to a circular cross-section as shown in the figure, and may be a cross-sectional rectangle, a cross-sectional triangle, a cross-sectional ellipse or the like. Further, when the present invention is implemented, a pair of elastic ring assemblies can be provided in a state of being separated in the axial direction as in the case of the conventional structure described in Patent Document 5 described above, for example. Contrary to the illustrated example, a spline hole can be provided on the output shaft side, and a spline shaft portion can be provided on the worm shaft side.

The principal part cutaway view which shows the 1st example of embodiment of this invention. The A section enlarged view of FIG. The figure similar to FIG. 2 which shows the Example of 2 examples which changed the number of the elastic rings which comprise an elastic ring aggregate | assembly according to the magnitude | size of transmission torque. The figure similar to FIG. 2 which shows the reference example (a) and Example (b) which changed the number and arrangement | positioning of the elastic ring which comprises an elastic ring assembly according to the shape and magnitude | size of an annular clearance. The elastic ring which comprises an elastic ring aggregate | assembly is shown, (a) is the figure seen from the axial direction, (b) is the figure seen from the side of (a) in the state which cut | disconnected a part. The partial cutting side view which shows the 1st example of a prior art structure. The expanded BB sectional drawing of FIG. The figure equivalent to the center part of FIG. 7 which shows the 2nd example of a conventional structure. The figure similar to FIG. 8 which shows the 3rd example of conventional structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Housing 4 Worm wheel 5 Worm tooth 6 Worm shaft 7 Electric motor 8 Worm 9a, 9b Rolling bearing 10 Pressing piece 11 Coil spring 12 Output shaft 13 Spline hole 14, 14a-14c Spline shaft part 15, 15a -15c Torque transmission joint 16, 16a-16c Locking groove 17, 17a-17c Annular gap 18 , 18a , 18b Elastic ring 19 Intermediate shaft 20 Steering gear unit 21 Female spline teeth 22 Male spline teeth 23 Elastic ring assembly 24 Elasticity ring

Claims (3)

In order to transmit torque between the ends of a pair of rotating shafts arranged in series with each other in the axial direction, an inner opening provided on the end surface of one of the rotating shafts. A spline hole having a female spline portion formed on the peripheral surface, and a spline shaft portion having a male spline portion formed on the outer peripheral surface provided at an end portion of the other rotary shaft of the two rotary shafts. A spline engagement between the shaft portion and the spline hole enables torque transmission between the rotating shafts, and the inner peripheral surface of the spline hole and the outer peripheral surface of the spline shaft portion In the torque transmission joint in which the elastic buffer member is provided in an elastically compressed state between the two peripheral surfaces, the elastic buffer member causes the plurality of elastic rings to overlap in the radial direction. also made collectively by the state Torque-transmitting joint, characterized in that it. By forming a concave groove-shaped locking groove over the entire circumference of the outer peripheral surface of the spline shaft portion that is axially distant from the male spline portion, the engagement groove and the inner peripheral surface of the spline hole are formed. The joint for torque transmission according to claim 1, wherein an annular annular gap having a constant radial dimension over the entire circumference is formed therebetween, and an elastic buffer member is provided in the annular gap. A housing that is supported by a fixed portion and does not rotate, and a steering rotation that is provided rotatably with respect to the housing and is rotated by an operation of a steering wheel, and gives a steering angle to a steered wheel as it rotates. A shaft, a worm wheel that is supported concentrically with the steering rotation shaft inside the housing and rotates together with the steering rotation shaft, and an axially intermediate portion of the worm shaft. A worm having worm teeth, in which the worm teeth are meshed with the worm wheel, and both end portions in the axial direction of the worm shaft are rotatably supported with respect to the housing by bearings, and the worm rotates. An electric motor for driving, and 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 freely transmitted. And In the electric power steering apparatus is, the torque-transmitting joint, the electric power steering apparatus which is a torque-transmitting joint as set forth in any one of claims 1-2.

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