JP2011156968A - Joint and electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint and an electric power steering device that can suppress a generation of an abnormal noise. <P>SOLUTION: A joint 33 has an elastic member 38 intervening between a first engage member 36 and a second engage member 37 and for transmitting a torque therebetween. The first engage member 36 includes a plurality of first coupling protrusions 42 protruding from a first engage member body in an axial direction thereof. The second engage member 37 includes a plurality of second coupling protrusions 52 protruding from a second engage member body in an axial direction thereof. The elastic member 38 includes an annularly-shaped elastic member body 61 and a plurality of coupling arms 63 extending from an inner circumference part 62 thereof in a radially inward direction R31. The plurality of first and second coupling protrusions 42 and 52 are alternately arranged with each other so as to sandwich the coupling arms 63 of the elastic member 38 in a circumferential direction C3, respectively. The inner circumference part 62 of the elastic member body 61 has position determining portions 65 and position determining portions 66 for determining positions of the first coupling protrusions 42 and the second coupling protrusions 52 in radial directions R3, respectively. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a torque transmission joint and an electric power steering apparatus.

Conventionally, for example, in an electric power steering apparatus, a joint that connects an output shaft of an electric motor and an input shaft of a reduction gear to each other so as to transmit torque is used. It has been proposed that the joint includes first and second engaging members and an elastic member that connects the first and second engaging members so as to transmit torque (for example, Patent Document 1). , 2, 3).
In the joints of Patent Documents 1, 2, and 3, the first and second engagement members each have a plurality of engagement protrusions. The elastic member of the joint of Patent Literatures 1 and 2 has an annular portion and a plurality of connecting arms extending radially outward from the outer periphery of the annular portion. The engaging protrusions of the first and second engaging members are alternately arranged in the circumferential direction with the connecting arm of the elastic member interposed therebetween. Further, in the joint of Patent Document 3, a plurality of elastic members are arranged in a ring shape, and the engagement protrusions of the first and second engagement members are alternately arranged in the circumferential direction with the corresponding elastic members interposed therebetween. Yes.

JP 2002-145083 A Special table 2002-518242 gazette JP 2009-190519 A

By the way, in the above-mentioned electric power steering device, abnormal noise may occur in relation to the above-described joint.
Therefore, an object of the present invention is to provide a joint and an electric power steering device that can suppress the generation of abnormal noise.

  In order to achieve the above object, the first aspect of the present invention is the first engagement member (36), the second engagement member (37), the first engagement member, and the second engagement member. An elastic member (38) interposed between engagement members and transmitting torque between the first engagement member and the second engagement member, wherein the first engagement member is annular The first engagement member main body (41) and the axial direction (X1) of the first engagement member main body projecting from the first engagement member main body to the circumferential direction of the first engagement member main body A plurality of first connecting protrusions (42) arranged in line (C1), wherein the second engaging member is an annular second engaging member main body (51) and the second engaging member. A plurality of second connection protrusions (52) protruding from the main body in the axial direction (X2) of the second engagement member main body and arranged in the circumferential direction (C2) of the second engagement member main body The elastic member includes an annular elastic member main body (61) and a plurality of connections extending from the inner periphery (62) of the elastic member main body to the radially inner side (R31) of the elastic member main body. The first connection protrusion and the second connection protrusion are alternately arranged to sandwich the corresponding connection arm of the elastic member in the circumferential direction (C3) of the elastic member body. And the inner periphery of the elastic member body has positioning portions (65, 66) for positioning the first connection protrusion and the second connection protrusion in the radial direction (R3) of the elastic member body. It is a coupling (33) characterized by being (Claim 1).

  According to the present invention, since the positioning portion is provided on the large-diameter elastic member main body arranged radially outward of the connecting arm, the span for positioning the first and second connecting protrusions can be lengthened. As a result, the positioning unit can accurately align the centers of the first engagement member, the second engagement member, and the elastic member with each other. Therefore, generation of vibration and noise when the joint rotates can be suppressed. Further, since the elastic member main body is disposed radially outward of the connecting arm, it is easy to handle when assembling, and as a result, the elastic member can be easily assembled to the first and second engaging members. Therefore, the elastic member can be accurately positioned with respect to the first and second engaging members.

  In the present invention, the elastic member is disposed radially inward of the elastic member main body, and the boss portion (67) connecting the inner ends (631) of the connecting arms in the radial direction of the elastic member main body to each other. ), The boss portion includes first and second end portions (671, 672) related to the axial direction (X3) of the elastic member body, and the first end portion (671) is the first end portion (671). The second end portion (672) may be fitted into the center hole (53) of the second engagement member body. (Claim 2). In this case, the center of the first engaging member, the second engaging member, and the elastic member can be aligned with each other with higher accuracy by the boss portion.

  In the present invention, the boss portion may elastically bias the first engagement member and the second engagement member in a direction opposite to the axial direction of the elastic member main body (claims). 3). In this case, for example, it is possible to prevent rattling of the bearing that rotatably supports the first engaging member, and to prevent rattling of the bearing that rotatably supports the second engaging member. It becomes possible. As a result, generation of vibration and noise can be suppressed when the joint rotates.

  In the present invention, the elastic member is disposed radially inward of the elastic member main body, and the boss portion (67) connecting the inner ends (631) of the connecting arms with respect to the radial direction of the elastic member main body. The boss portion may elastically urge the first engagement member and the second engagement member in a direction opposite to the axial direction (X3) of the elastic member main body (claims). 4). In this case, for example, it is possible to prevent rattling of the bearing that rotatably supports the first engaging member, and to prevent rattling of the bearing that rotatably supports the second engaging member. It becomes possible. As a result, generation of vibration and noise can be suppressed when the joint rotates.

  The present invention further includes a reduction gear (24) for transmitting the output rotation of the electric motor (23) for assisting steering to the steering mechanism (11), and the joint according to the present invention, wherein the first engagement is performed. The member is connected to the output shaft (231) of the electric motor so as to be able to rotate together, and the second engaging member is connected to the input shaft (26) of the speed reducer so as to be able to rotate together. An electric power steering device may be used (claim 5). In this case, the vibration of the electric power steering device and the generation of abnormal noise can be suppressed.

  In addition, although the alphanumeric characters in the parentheses indicate reference signs of corresponding components in the embodiments described later, the scope of the claims is not limited by these reference signs.

It is a mimetic diagram of a schematic structure of an electric power steering device to which a joint of one embodiment of the present invention is applied. It is sectional drawing of the reduction gear of FIG. FIG. 3 is an enlarged view of the joint of FIG. 2 and its surroundings. It is sectional drawing of the IV-IV cross section of FIG. FIG. 5A is a cross-sectional view of the first engagement member, showing a Va-Va cross-section of FIG. 5B, and FIG. 5B is a side view of the first engagement member. . 6A is a side view of the second engagement member, and FIG. 6B is a cross-sectional view taken along the line VIb-VIb in FIG. 6A. FIG. 7A is a front view of the elastic member, and FIG. 7B is a side view of the elastic member. It is sectional drawing of the modification of the relationship about the 2nd engagement member of the coupling of this invention, an elastic member, and an output shaft.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present embodiment, the case where the joint is applied to an electric power steering device of an automobile will be described. In addition, the joint of this embodiment may be applied to apparatuses other than the electric power steering apparatus.
FIG. 1 is a schematic diagram of a schematic configuration of an electric power steering apparatus to which a joint according to an embodiment of the present invention is applied. Referring to FIG. 1, an electric power steering system (EPS) 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, and a first universal joint 4 attached to the steering shaft 3. A pinion shaft 7 connected to the intermediate shaft 5 via a second universal joint 6, and a rack 9 that meshes with a pinion 8 provided near the end of the pinion shaft 7. And a rack shaft 10 as a turning shaft extending in the left-right direction of the automobile.

  The pinion shaft 7 and the rack shaft 10 constitute a steering mechanism 11 including a rack and pinion mechanism. The rack shaft 10 is supported in a rack housing 13 fixed to a vehicle body (not shown) so as to be linearly reciprocable via a plurality of bearings (not shown). A pair of tie rods 14 are coupled to the rack shaft 10. Each tie rod 14 is connected to a corresponding steered wheel 16 via a corresponding knuckle arm.

When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted by the pinion 8 and the rack 9 into a linear motion of the rack shaft 10 in the left-right direction of the automobile. Thereby, the turning of the steered wheels 16 is achieved.
The steering shaft 3 is divided into an input shaft 17 connected to the steering member 2 and an output shaft 18 connected to the pinion shaft 7. The input shaft 17 and the output shaft 18 are connected to each other on the same axis via a torsion bar 19. When steering torque is input to the input shaft 17, the torsion bar 19 is elastically torsionally deformed, whereby the input shaft 17 and the output shaft 18 are rotated relative to each other.

  A torque sensor 20 that detects a steering torque based on the amount of relative rotational displacement between the input shaft 17 and the output shaft 18 via the torsion bar 19 is provided. A vehicle speed sensor 21 for detecting the vehicle speed is also provided. An ECU (Electronic Control Unit) 22 is provided as a control device. Further, an electric motor 23 as an actuator for generating a steering force (steering assist force in the present embodiment) and a speed reducer 24 that decelerates the output rotation of the electric motor 23 are provided.

  Detection signals from the torque sensor 20 and the vehicle speed sensor 21 are input to the ECU 22. The ECU 22 controls the steering assisting electric motor 23 based on the torque detection result, the vehicle speed detection result, and the like. The output rotation of the electric motor 23 is decelerated via the speed reducer 24, transmitted to the pinion shaft 7, and converted into a linear motion of the rack shaft 10, thereby assisting in steering.

FIG. 2 is a cross-sectional view of the speed reducer 24 of FIG. Referring to FIG. 2, the speed reducer 24 has a worm shaft 26 as a drive gear that is rotationally driven by an electric motor 23, and a worm wheel 27 as a driven gear that meshes with the worm shaft 26. The worm wheel 27 is coupled to the output shaft 18 of the steering shaft 3 so as to be able to rotate together.
The worm shaft 26 functions as an input shaft for the speed reducer 24. The worm shaft 26 includes a first end 261 and a second end 262 in the axial direction of the worm shaft 26, and a worm 263 as a tooth portion formed in an intermediate portion in the axial direction of the worm shaft 26. is doing. The first end 261 is rotatably supported by a bearing 31 held by the housing 28. The second end 262 is rotatably supported by a bearing 32 held by the housing 28. The first end 261 of the worm shaft 26 and the output shaft 231 of the electric motor 23 are arranged concentrically with each other. The output shaft 231 and the first end 261 of the worm shaft 26 are connected to each other via a joint 33 so that torque can be transmitted.

  FIG. 3 is an enlarged view of the joint 33 in FIG. 2 and its surroundings. 4 is a cross-sectional view taken along the line IV-IV in FIG. With reference to FIGS. 3 and 4, the joint 33 includes a first engagement member 36, a second engagement member 37, and an elastic member 38. The elastic member 38 is interposed between the first engagement member 36 and the second engagement member 37, and transmits torque between the first engagement member 36 and the second engagement member 37.

The first engagement member 36 is coupled to the output shaft 231 of the electric motor 23 as the first shaft so as to be able to rotate together. The second engagement member 37 is connected to the worm shaft 26 of the speed reducer 24 as a second shaft so as to be able to rotate together. The joint 33 transmits torque between the first shaft and the second shaft, which are torque transmission targets.
5A is a cross-sectional view of the first engagement member 36, showing a Va-Va cross section of FIG. 5B, and FIG. 5B is a side view of the first engagement member 36. It is. 5 (a) and 5 (b), the first engagement member 36 includes an annular first engagement member main body 41 and a first engagement member main body 41 to a first engagement. A plurality of first connecting protrusions 42 protruding in the axial direction X1 of the combined member main body 41 are included. The plurality of first connection protrusions 42 are arranged in the circumferential direction C1 of the first engagement member main body 41.

  Specifically, the first engaging member 36 is formed of a hard member, for example, metal. Steel can be exemplified as the metal. The first engagement member main body 41 and the plurality of first connection protrusions 42 are integrally formed by the above-described hard member as a single material. The first engagement member main body 41 has a center hole 43. For example, four of the plurality of first connection protrusions 42 are formed in the same shape as each other, and are evenly arranged in the circumferential direction C1. Each of the first connection protrusions 42 has a pair of torque transmission surfaces 44 that face each other in the circumferential direction C1.

  6A is a side view of the second engagement member 37, and FIG. 6B is a cross-sectional view taken along the line VIb-VIb of FIG. 6A. Referring to FIGS. 6A and 6B, the second engagement member 37 includes an annular second engagement member main body 51 and a second engagement member main body 51 to a second engagement. A plurality of second connection protrusions 52 protruding in the axial direction X2 of the combined member main body 51 are included. The plurality of second connection protrusions 52 are arranged in the circumferential direction C <b> 2 of the second engagement member main body 51.

  Specifically, the second engagement member 37 is formed of a hard member, for example, metal. Steel can be exemplified as the metal. The second engaging member main body 51 and the plurality of second connecting projections 52 are integrally formed by the above-described hard member as a single material. The second engagement member main body 51 has a center hole 53. For example, four of the plurality of second connection protrusions 52 are formed in the same shape and are evenly arranged in the circumferential direction C2. Each of the second connection protrusions 52 has a pair of torque transmission surfaces 54 facing each other in the circumferential direction C2.

FIG. 7A is a front view of the elastic member 38, and FIG. 7B is a side view of the elastic member 38. Referring to FIGS. 7A and 7B, the elastic member 38 includes an annular elastic member main body 61 and an inner circumference 62 of the elastic member main body 61 extending inward in the radial direction R31 of the elastic member main body 61. It includes a plurality of connecting arms 63 provided.
The elastic member 38 is formed of an elastic body such as a rubber material or a synthetic resin material. Examples of the rubber material include synthetic rubber. The elastic member body 61 and the plurality of connecting arms 63 are integrally formed by the above-described elastic body as a single material.

The plurality of connecting arms 63 are arranged at equal intervals in the circumferential direction C <b> 3 of the elastic member main body 61. Each connecting arm 63 has a pair of torque transmission surfaces 64 facing the circumferential direction C3 of the elastic member main body 61.
Referring to FIGS. 3 and 4, the first connection protrusions 42 and the second connection protrusions 52 are alternately arranged to sandwich the corresponding connection arms 63 of the elastic member 38 in the circumferential direction C <b> 3 of the elastic member main body 61. Yes. One torque transmission surface 64 of the coupling arm 63 of the elastic member 38 and the torque transmission surface 44 of the first coupling projection 42 of the first engagement member 36 are in contact with each other. The other torque transmission surface 64 of the coupling arm 63 of the elastic member 38 and the torque transmission surface 54 of the second coupling projection 52 of the second engagement member 37 are in contact with each other. As a result, bidirectional torque is transmitted between the first engagement member 36 and the second engagement member 37 via the elastic member 38. As a result, the output of the electric motor 23 is transmitted to the worm shaft 26 via the joint 33.

  In the present embodiment, the inner periphery 62 of the elastic member main body 61 has positioning portions 65 and 66 for positioning the first connecting protrusion 42 and the second connecting protrusion 52 in the radial direction R3 of the elastic member main body 61. . Since the positioning portions 65 and 66 are provided on the large-diameter elastic member main body 61 disposed on the radially outer side R32 of the connecting arm 63, the first connecting protrusion 42 and the second connecting protrusion 52 are positioned. Can extend the span. As a result, the positioning portions 65 and 66 can accurately align the centers of the first engagement member 36, the second engagement member 37, and the elastic member 38 with each other. Therefore, generation | occurrence | production of the vibration and noise when the coupling 33 rotates can be suppressed.

Since the outer periphery of the first engagement member 36 and the outer periphery of the second engagement member 37 can usually be formed with high accuracy, they are positioned with high accuracy by the positioning portions 65 and 66 of the elastic member 38.
Further, since the elastic member main body 61 is arranged on the radially outer side R32 of the connecting arm 63, it is easy to handle when assembling, and as a result, the elastic member 38 is easily attached to the first and second engaging members 36, 37. Can be assembled. Therefore, the elastic member 38 can be accurately positioned with respect to the first and second engaging members 36 and 37.

Specifically, the positioning portion 65 positions the first connection protrusion 42 and is disposed at a plurality of locations. There are at least three positioning portions 65, four in this embodiment. The plurality of positioning portions 65 are equally arranged in the circumferential direction C <b> 3 of the elastic member main body 61.
The positioning portion 66 positions the second connecting projection 52 and is arranged at a plurality of locations. There are at least three positioning portions 66, four in the present embodiment. The plurality of positioning portions 66 are equally arranged in the circumferential direction C <b> 3 of the elastic member main body 61.

The positioning part 65 and the positioning part 66 are formed in the same manner. The plurality of positioning portions 65 and the plurality of positioning portions 66 are equally spaced apart from each other in the circumferential direction C3 of the elastic member main body 61 and are alternately arranged in the circumferential direction C3 of the elastic member main body 61.
Referring to FIGS. 3 and 5B, each first connection protrusion 42 has a positioned portion 421 that contacts the positioning portion 65 of the elastic member main body 61 of the elastic member 38. The positioned portion 421 is formed at the outer end of the first connection protrusion 42 in the radial direction R1 of the first engagement member main body 41. The plurality of positioned portions 421 are equally disposed in the circumferential direction C1 of the first engagement member main body 41.

The positioning portion 65 and the positioned portion 421 are opposed to each other in the radial direction R3 of the elastic member main body 61 and are in contact with each other. Thereby, the positioning part 65 positions the to-be-positioned part 421 in the radial direction R3 of the elastic member main body 61.
With reference to FIG. 3 and FIG. 6A, each second connecting projection 52 has a positioned portion 521 that contacts the positioning portion 66 of the elastic member main body 61 of the elastic member 38. The positioned portion 521 is formed at the outer end of the second connection projection 52 in the radial direction R2 of the second engagement member main body 51. The plurality of positioned portions 521 are equally arranged in the circumferential direction C <b> 2 of the second engagement member main body 51.

The positioning portion 66 and the positioned portion 521 are opposed to each other in the radial direction R3 of the elastic member main body 61 and are in contact with each other. Thereby, the positioning part 66 positions the to-be-positioned part 521 in the radial direction R3 of the elastic member main body 61.
Referring to FIGS. 3 and 5A, the center hole 43 of the first engagement member main body 41 is connected to the first engagement member main body 41 in the axial direction X1 of the first engagement member main body 41. Has penetrated. An output shaft 231 as a first shaft is connected to the center hole 43 so as to be able to rotate together. Specifically, the output shaft 231 is fixed to the center hole 43 by press fitting.

3 and 6B, the center hole 53 of the second engagement member main body 51 is connected to the second engagement member main body 51 in the axial direction X2 of the second engagement member main body 51. Has penetrated. A worm shaft 26 as a second shaft is connected to the center hole 53 so as to be able to rotate together. Specifically, the worm shaft 26 is fixed to the center hole 53 by press-fitting.
Referring to FIG. 3, the center hole 43 of the first engagement member main body 41 is fitted with a first fitting portion 431 into which the output shaft 231 is fitted and a boss portion 67 (to be described later) of the elastic member 38. And a second fitting portion 432. The center hole 53 of the second engagement member main body 51 includes a first fitting portion 531 into which the worm shaft 26 is fitted, and a second fitting portion 532 into which the boss portion 67 of the elastic member 38 is fitted. Have.

  The first fitting portion 431 and the second fitting portion 432 of the center hole 43 of the first engagement member main body 41 are disposed concentrically with each other. The first fitting portion 431 and the second fitting portion 432 may be formed with the same inner diameter, or may be formed with different inner diameters. In the present embodiment, the first fitting portion 431 is formed with a smaller diameter than the second fitting portion 432. The first fitting portion 431 and the second fitting portion 432 are connected via a step portion 433. The same applies to the center hole 53, and the first fitting portion 531 and the second fitting portion 532 having a larger diameter than this are connected via a step portion 533.

With reference to FIG. 7A and FIG. 7B, the elastic member 38 has a boss portion 67 in addition to the elastic member main body 61 and the plurality of connecting arms 63. The elastic member main body 61, the plurality of connecting arms 63, and the boss portion 67 are integrally formed by the above-described elastic body as a single material.
The boss portion 67 is disposed on the radially inner side R <b> 31 of the elastic member main body 61. The boss 67 connects the inner ends 631 of the connecting arms 63 with respect to the radial direction R3 of the elastic member body 61 to each other. The boss portion 67 includes first and second end portions 671 and 672 regarding the axial direction X3 of the elastic member main body 61.

The first end 671 and the second end 672 each have an outer periphery formed of a cylindrical surface, and these outer periphery are formed concentrically with each other. Further, the first end 671 protrudes from the end surface of the connecting arm 63 with respect to the axial direction X3 of the elastic member main body 61. The second end 672 protrudes from the end surface of the connecting arm 63 with respect to the axial direction X3 of the elastic member main body 61.
Referring to FIGS. 3 and 4, the boss portion 67 has an outer periphery 68 at an intermediate portion in the radial direction R3 and the axial direction X3 of the elastic member main body 61. The outer periphery 68 has positioning portions 69 and 70 for positioning the first connecting protrusion 42 and the second connecting protrusion 52 in the radial direction R3 of the elastic member main body 61. By using the positioning portions 69 and 70 in addition to the positioning portions 65 and 66, the centers of the first engaging member 36, the second engaging member 37, and the elastic member 38 are aligned with each other with higher accuracy. be able to. Therefore, generation of vibration and noise when the joint 33 rotates can be prevented more reliably.

  Specifically, the positioning portion 69 positions the first connecting protrusion 42 and is provided at a plurality of locations. The positioning unit 70 positions the second connecting protrusion 52 and is provided at a plurality of locations. The plurality of positioning portions 69 and the plurality of positioning portions 70 are equally spaced apart from each other in the circumferential direction C3 of the elastic member main body 61 and are alternately arranged in the circumferential direction C3 of the elastic member main body 61.

With reference to FIGS. 4 and 5B, each first connection protrusion 42 has a positioned portion 422 that contacts the positioning portion 69 of the boss portion 67. The positioned portion 422 is formed at the inner end of the first connection protrusion 42 in the radial direction R1 of the first engagement member main body 41.
With reference to FIG. 4 and FIG. 6A, each second connecting projection 52 has a positioned portion 522 that comes into contact with the positioning portion 70 of the boss portion 67. The positioned portion 522 is formed at the inner end of the second connection protrusion 52 in the radial direction R <b> 2 of the second engagement member main body 51.

  With reference to FIG. 3, the first end 671 of the boss 67 is fitted into the second fitting portion 432 of the center hole 43 of the first engagement member main body 41. The second end portion 672 of the boss portion 67 is fitted into the second fitting portion 532 of the center hole 53 of the second engagement member main body 51. Thereby, the centers of the first engaging member 36, the second engaging member 37, and the elastic member 38 can be aligned with each other with higher accuracy.

  Referring to FIG. 2, the boss portion 67 elastically biases the first engagement member 36 and the second engagement member 37 in the direction opposite to the axial direction X3 of the elastic member main body 61. Thereby, for example, as will be described later, a bearing that rotatably supports the first engagement member 36 (specifically, a bearing 232 that rotatably supports the output shaft 231 of the electric motor 23 corresponds). Bearings that prevent rattling and bearings that rotatably support the second engagement member 37 (specifically, bearings 31 and 32 that rotatably support the worm shaft 26 are equivalent). It becomes possible to prevent rattling. As a result, generation of vibration and noise can be suppressed when the joint 33 rotates.

  Further, when the boss portion 67 elastically biases the first engagement member 36 and the second engagement member 37 in the direction opposite to the axial direction X3 of the elastic member main body 61, such a boss portion 67, An elastic member main body 61 for positioning the first and second engaging members 36 and 37 with each other is formed integrally with the connecting arm 63. Thereby, the inclination of the boss | hub part 67 with respect to the axial direction X3 of the elastic member main body 61 is prevented. As a result, the boss 67 can stably elastically bias the first engagement member 36 and the second engagement member 37. Therefore, it contributes to the prevention of vibration and noise.

The elastic member 38 has both a function of transmitting torque and a function of elastically urging the first and second engaging members 36 and 37 in the direction opposite to the axial direction X3. The number of parts can be reduced as compared with the case of achieving with a plurality of parts.
The electric motor 23 has an output shaft 231 and a bearing 232 that rotatably supports the output shaft 231. The bearing 232 is a rolling bearing. The bearings 31 and 32 are rolling bearings. Hereinafter, description will be made in accordance with the bearing 31. Similar effects can be obtained with respect to the bearing 232 of the electric motor 23.

With reference to FIG. 3, the bearing 31 includes an outer ring 311, an inner ring 312, and a plurality of rolling elements 313. An inner ring 312 is fitted to the outer periphery of the first end 261 of the worm shaft 26 and is fixed to the outer periphery. The outer ring 311 is received in the axial direction of the worm axial direction 26 in contact with the stepped portion of the bearing holding portion 281 provided in the housing 28.
The boss 67 of the elastic member 38 is formed between the first and second engaging members 36 and 37, more specifically, the step 433 of the center holes 43 and 53 of the first and second engaging members 36 and 37. , 533 are interposed in a state of being elastically compressed in the axial direction X3.

  The biasing force by the elastic member 38 that biases the second engagement member 37 in the axial direction X3 is sequentially transmitted from the second engagement member 37 to the inner ring 312, the rolling element 313, and the outer ring 311 of the bearing 31. The bearing holding portion 281 is received. At this time, the internal clearance of the bearing 31 is removed. Further, a preload can be applied to the bearing 31 in the axial direction of the worm shaft 26. Thereby, the vibration and noise resulting from the internal clearance of the bearing 31 can be reduced.

  Further, the boss portion 67 is interposed between the output shaft 231 and the worm shaft 26 in a state of being elastically compressed in the axial direction X3. Thereby, the boss portion 67 elastically biases the output shaft 231 and the worm shaft 26 in the direction opposite to the axial direction X3. The output shaft 231 and the first engagement member 36 are fixed to each other. The worm shaft 26 and the second engagement member 37 are fixed to each other. Accordingly, the first engagement member 36 and the second engagement member 37 are elastically urged to each other in the direction opposite to the axial direction X3, so that the above-described effect due to this elastic urging is obtained.

Further, the backlash of the worm gear may be removed using the biasing force of the elastic member 38 that biases the worm shaft 26 in the axial direction of the worm shaft 26.
With reference to FIGS. 1 and 2, the joint 33 of the present embodiment includes an output shaft 231 of the steering assisting electric motor 23 in the electric power steering apparatus 1 and a reduction gear that transmits this output rotation to the steering mechanism 11. It is used to connect the worm shaft 26 that is the 24 input shafts so that torque can be transmitted. The first engagement member 36 of the joint 33 is coupled to the output shaft 231 of the electric motor 23 so as to be able to rotate together. The second engagement member 37 of the joint 33 is connected to the worm shaft 26 of the speed reducer 24 so as to be able to rotate together. Due to the above-described effects of the joint 33 of the present embodiment, vibrations and abnormal noises of the electric power steering apparatus 1 can be suppressed. For example, since the output shaft 231 of the electric motor 23 is stably urged in the axial direction by the elastic member 38 of the joint 33, the generation of noise in the electric motor 23 can be prevented.

Moreover, the following modifications can be considered about this embodiment. In the following description, the points different from the above-described embodiment will be mainly described. In addition, about another structure, it is the same as that of the above-mentioned embodiment.
For example, FIG. 8 is a sectional view of a modified example of the relationship between the second engaging member 37, the elastic member 38, and the worm shaft 26 of the joint 33 of the present invention. Referring to FIG. 8, second end portion 672 of boss portion 67 is not fitted in center hole 53. The boss portion 67 in this state elastically urges the worm shaft 26 and elastically urges the second engagement member 37 via the worm shaft 26. Further, the boss portion 67 may elastically bias the second engagement member 37 without contacting the worm shaft 26.

Further, although not shown, similarly, the boss portion 67 is not fitted into the center hole 43 and does not come into contact with either the output shaft 231 or the first engagement member 36. Alternatively, the other may be elastically biased.
Also in these cases, the above-described effect can be obtained by the boss portion 67 elastically urging the first and second engaging members 36 and 37 in the opposite direction of the axial direction X3.

Referring to FIG. 3, boss portion 67 elastically biases output shaft 231 and first engagement member 36, worm shaft 26 and second engagement member 37 in the direction opposite to axial direction X3. This can be abolished. It is also conceivable to eliminate the positioning parts 69 and 70 on the outer periphery 68 of the boss part 67.
It is also conceivable that the boss portion 67 of the elastic member 38 of the joint 33 is configured as a separate part from the elastic member main body 61 and the plurality of connecting arms 63 which are the remaining portions of the elastic member 38. Further, it is conceivable to eliminate the boss portion 67 of the elastic member 38 of the joint 33.

  Further, in the above-described embodiment, the example in which the present invention is applied to the so-called column assist type electric power steering device 1 has been described. The present invention may be applied to an electric power steering device of the type. In addition, various changes can be made within the scope of the matters described in the claims.

DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus, 11 ... Steering mechanism, 23 ... Electric motor, 24 ... Reduction gear, 26 ... Worm shaft (input shaft of reduction gear), 33 ... Joint, 36 ... First engagement member, 37 ... 2nd engaging member, 38 ... elastic member, 41 ... 1st engaging member main body, 42 ... 1st connection protrusion, 43, 53 ... center hole, 51 ... 2nd engaging member main body, 52 ... 1st 2 connection protrusions, 61 ... elastic member main body, 62 ... inner circumference, 63 ... connection arm, 65, 66 ... positioning part, 67 ... boss part, 231 ... output shaft of electric motor, 631 ... inner end of connection arm, 671 ... 1st edge part, 672 ... 2nd edge part, C1, C2, C3 ... Circumferential direction, R3 ... Radial direction, R31 ... Radial inward, X1, X2, X3 ... Axial direction.

Claims (5)

A first engagement member;
A second engagement member;
An elastic member interposed between the first engagement member and the second engagement member, and transmitting torque between the first engagement member and the second engagement member,
The first engagement member protrudes in the axial direction of the first engagement member main body from the first engagement member main body, and the first engagement member main body. A plurality of first connection protrusions arranged in the circumferential direction of the main body,
The second engagement member protrudes in the axial direction of the second engagement member main body from the second engagement member main body, and the second engagement member main body. A plurality of second connection protrusions arranged in the circumferential direction of the main body,
The elastic member includes an annular elastic member main body, and a plurality of connecting arms extending radially inward from the inner periphery of the elastic member main body,
The first connection protrusions and the second connection protrusions are alternately arranged to sandwich the corresponding connection arms of the elastic member in the circumferential direction of the elastic member body,
The joint, wherein the inner periphery of the elastic member body has a positioning portion for positioning the first connection protrusion and the second connection protrusion in the radial direction of the elastic member body. In claim 1,
The elastic member includes a boss portion that is disposed radially inward of the elastic member body, and that connects the inner ends of the connecting arms with respect to the radial direction of the elastic member body.
The boss portion includes first and second end portions related to the axial direction of the elastic member body,
The first end is fitted into a center hole of the first engagement member body,
The joint, wherein the second end is fitted in a center hole of the second engagement member main body.   3. The joint according to claim 2, wherein the boss portion elastically urges the first engagement member and the second engagement member in a direction opposite to the axial direction of the elastic member body. In claim 1,
The elastic member includes a boss portion that is disposed radially inward of the elastic member main body and connects the inner ends of the connecting arms with respect to the radial direction of the elastic member main body,
The boss portion elastically biases the first engagement member and the second engagement member in a direction opposite to the axial direction of the elastic member main body. A speed reducer that transmits the output rotation of the steering assist electric motor to the steering mechanism;
A joint according to any one of claims 1 to 4,
The first engagement member is coupled to the output shaft of the electric motor so as to be able to rotate together,
The electric power steering apparatus, wherein the second engagement member is connected to an input shaft of the speed reducer so as to be able to rotate together.

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