Worm reducer and assembling method thereof

Abstract

The holder (19) has a first grease supply section (74) for supplying grease to a contact section (P1) between the elastic member (21) and the pad base section (55), the first grease supply section (74) being in the vicinity of the contact section (P1) between the elastic member (21) and the pad base section (55). A second grease supply part (75) for supplying grease to a contact part (P2) between the elastic member (21) and the protruding part (44) is provided in the vicinity of the contact part (P2) between the elastic member (21) and the protruding part (44).

Description

Technical Field

[0001] The present disclosure relates to a worm speed reducer assembled in, for example, an electric power steering device and an assembling method thereof. Background Art

[0002] When applying a steering angle to the steering wheels of a vehicle, an electric power steering system using an electric motor as an auxiliary power source is widely used as a device for reducing the force required to operate the steering wheel.

[0003] Electric power steering systems are broadly classified into different structures depending on the installation location of the electric motor. Specifically, various configurations have been proposed, including a column-assisted type in which auxiliary power is applied to a steering shaft rotatably supported inside the steering column; a pinion-assisted type in which auxiliary power is applied to a pinion shaft serving as the input shaft of the steering gear unit; and a dual-pinion type in which the steering gear unit includes a pinion shaft separate from the pinion shaft serving as the input shaft and auxiliary power is applied to this pinion shaft.

[0004] In either configuration, the auxiliary power from the electric motor is applied via a speed reducer to a shaft component that rotates or moves linearly in response to steering wheel operation. Worm speed reducers are widely used as such speed reducers. The worm speed reducer that constitutes an electric power steering system includes a worm that is rotationally driven by the electric motor and a worm wheel that meshes with the worm.

[0005] Figure 23 An example of a conventional structure of a worm speed reducer is shown in Japanese Patent No. 4381024. A worm speed reducer 100 includes a housing 101, a worm wheel 102, and a worm 103.

[0006] The housing 101 includes a worm wheel housing portion 104 and a worm housing portion 105 , which is arranged such that its central axis is twisted relative to the central axis of the worm wheel housing portion 104 and an axially intermediate portion opens into the worm wheel housing portion 104 .

[0007] The worm wheel 102 has gear teeth 106 on its outer peripheral surface, and is supported and fixed around a rotation shaft 107 rotatably supported inside the worm wheel housing portion 104 , coaxially with the rotation shaft 107 .

[0008] The worm 103 has worm teeth 108 on the outer peripheral surface of the axial middle portion that mesh with the gear teeth 106. The worm 103 is rotatably supported inside the worm housing 105 by two ball bearings 109a and 109b at two locations in the axial direction across the worm teeth 108. The distal end of the worm 103 in the two ball bearings 109a and 109b ( Figure 23The outer ring of the ball bearing 109a (on the right side) is pressed into the bracket 110, and the bracket 110 is embedded and fixed inside the inner end side of the worm housing 105. The inner ring of the ball bearing 109a is fitted into the large diameter portion 111 of the worm 103 located closer to the end side than the worm teeth 108 through a bushing 112 made of synthetic resin through a gap fit. That is, the inner ring of the ball bearing 109a is fitted into the bushing 112 that is fitted into the large diameter portion 111 of the worm 103 in a gap fit manner without any shaking. The base end side ( Figure 23 The outer ring of ball bearing 109b (on the left side of the worm) is loosely fitted into the opening of worm housing 105, while the inner ring of ball bearing 109b is externally fitted into the base end of worm 103. The output shaft of electric motor 113 is connected to the base end of worm 103 in a torque-transmittable manner. In other words, worm 103 can be rotationally driven by electric motor 113.

[0009] In worm reducer 100, backlash inevitably occurs at the meshing point between gear teeth 106 and worm teeth 108 due to dimensional and assembly errors among the components that comprise worm reducer 100. This backlash sometimes produces a harsh rattling sound at the meshing point when the steering wheel's rotational direction is changed. In the illustrated example, to suppress this rattling sound, the distal end of worm 103 is elastically biased toward worm wheel 102.

[0010] That is, the base end of the worm 103 is supported by a ball bearing 109b having a radial clearance so as to be able to slightly swing relative to the worm housing 105. An annular gap exists throughout the entire circumference between the outer peripheral surface of the large diameter portion 111 of the worm 103 and the inner peripheral surface of the bushing 112. A liner 114 is embedded in the distal end of the worm 103, and a torsion coil spring 115 is provided between the liner 114 and the bracket 110. The torsion coil spring 115 controls the worm 103 to move in the first direction (the direction in which the worm 103 moves relative to the worm wheel 102) in the direction of the movement. Figure 23 In the vertical direction), the liner 114 is elastically pressed toward the worm wheel 102 side, thereby moving the distal end portion of the worm 103 toward the worm wheel 102 side (in the first direction). Figure 23 Thus, the backlash between the gear teeth 106 and the worm teeth 108 is suppressed, and the generation of the gear rattling sound is suppressed.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent No. 4381024 Summary of the Invention

[0014] Technical problem that the invention aims to solve

[0015] In the structure described in Japanese Patent Gazette No. 4381024, in order to be able to press the distal end of the worm 103 in a direction close to the worm wheel 102, an annular gap exists throughout the entire circumference between the outer peripheral surface of the large diameter portion 111 of the worm 103 and the inner peripheral surface of the bushing 112. In addition, although smaller than the annular gap existing between the outer peripheral surface of the large diameter portion 111 of the worm 103 and the inner peripheral surface of the bushing 112, an annular gap also exists throughout the entire circumference between the distal end of the worm 103 and the through hole of the gasket 114. Therefore, when the rotation direction of the steering wheel is changed, that is, when the rotation direction of the worm 103 is changed, the reaction force applied from the gear teeth 106 to the worm teeth 108 in the direction opposite to the first direction and the axial direction of the worm housing 105, that is, the second direction ( Figure 23 The third direction ( Figure 23 The direction of the component in the front-back direction (in the front-back direction) changes, and the distal end of the worm 103 may be displaced violently in the third direction. Therefore, there is room for improvement in suppressing abnormal noises such as gear rattling.

[0016] The purpose of the present disclosure is to provide a worm reducer and an assembly method thereof, which can make it difficult for the end portion of the worm to displace in a third direction that is orthogonal to the force application direction of the end portion, i.e., the first direction, and the axial direction of the worm housing, i.e., the second direction, when the rotation direction of the worm changes, and can also make the assembly operation more workable.

[0017] Technical means to solve the problem

[0018] A worm speed reducer according to one embodiment of the present disclosure includes a housing, a worm wheel, a worm, a bracket, a spacer, and an elastic member.

[0019] The housing includes a worm wheel accommodation portion and a worm accommodation portion. The worm accommodation portion is arranged at a position twisted relative to the worm wheel accommodation portion, and an axially intermediate portion opens to the worm wheel accommodation portion.

[0020] The worm wheel has gear teeth on its outer peripheral surface and is rotatably supported inside the worm wheel housing portion.

[0021] The worm has worm teeth meshing with the gear teeth on an outer peripheral surface, and is rotatably supported inside the worm housing portion.

[0022] The bracket includes a protruding portion and two bracket engaging portions, and is disposed between a distal end portion of the worm and the worm accommodating portion.

[0023] The protrusion includes two guide portions, which are separately arranged in a third direction orthogonal to both the first direction and the second direction. The first direction is the direction of movement of the distal end of the worm relative to the worm wheel, and the second direction is the axial direction of the worm housing.

[0024] The two bracket engaging portions are arranged on mutually opposing inner side surfaces of the two guide portions.

[0025] The gasket includes a gasket base, two gasket engaging portions, and a gasket elastic pressing portion, and is externally fitted on the distal end of the worm.

[0026] The pad base is disposed between the two guide portions.

[0027] The two gasket engaging portions are provided on the side surfaces of the gasket base on both sides in the third direction and are in contact with the two bracket engaging portions.

[0028] The gasket elastic pressing portion applies preload to a contact portion between the bracket engaging portion and the gasket engaging portion by elastically pressing a portion of the bracket toward the second direction.

[0029] The elastic member is provided so as to bridge the protrusion and the spacer base, and elastically urges the distal end of the worm toward the worm wheel via the spacer.

[0030] In particular, in a worm reducer of one embodiment of the present invention, the bracket or the gasket has a first grease supply portion for supplying grease to the contact portion between the elastic component and the gasket base near the contact portion between the elastic component and the gasket base, and the bracket has a second grease supply portion for supplying grease to the contact portion between the elastic component and the protrusion near the contact portion between the elastic component and the protrusion.

[0031] In one embodiment of the worm reducer disclosed herein, the bracket may include a side plate portion bent radially outward from the base end of the protruding portion. In this case, the first grease supply portion may be provided so as to extend in the second direction through a portion of the side plate portion whose circumferential phase substantially coincides with a contact portion between the elastic member and the base of the gasket.

[0032] In a worm reducer of one embodiment of the present disclosure, the second grease supply portion can be provided in a manner that radially penetrates a portion of the protrusion and has a circumferential phase that is substantially consistent with that of the contact portion, wherein the contact portion is the contact portion between the elastic component and the protrusion.

[0033] In the worm reducer according to one aspect of the present disclosure, the protruding portion may include a connecting portion connecting end portions of the two guide portions on the side closer to the worm wheel in the first direction.

[0034] In a worm reducer of one embodiment of the present invention, the two bracket engaging portions can be formed by two bracket inclined surfaces that are inclined in directions approaching each other as they move toward one side of the second direction, and the two gasket engaging portions can be formed by two gasket inclined surfaces that are in surface contact with the two bracket inclined surfaces.

[0035] In a worm reducer of one embodiment of the present invention, the above-mentioned gasket elastic pressing part can be composed of two gasket elastic pressing plates, the two gasket elastic pressing plates are located at a position closer to the side of the above-mentioned second direction than the two gasket clamping parts, and respectively extend from the central part of the above-mentioned gasket in the above-mentioned third direction toward the side separated from each other in the above-mentioned third direction, the two above-mentioned guide parts can respectively have a bracket pressed surface on the end face on one side of the above-mentioned second direction, and can apply pre-pressure to the contact part between the above-mentioned bracket clamping part and the above-mentioned gasket clamping part by utilizing the two gasket elastic pressing plates to elastically press the above-mentioned bracket pressed surface toward the other side of the above-mentioned second direction.

[0036] In this case, each of the two gasket elastic pressing plates may include a slit penetrating in the second direction and extending in the first direction at an end portion on a center side of the gasket in the third direction.

[0037] In the worm speed reducer according to one aspect of the present disclosure, the elastic member may be formed of a leaf spring.

[0038] An assembly method for a worm reducer according to one embodiment of the present invention is an assembly method for a worm reducer according to one embodiment of the present invention, comprising the following steps: on the inner side of the worm housing portion, in a state where the bracket, the gasket and the elastic component are assembled, grease is filled into the inner side of the worm housing portion, a portion of the grease is supplied to the contact portion between the elastic component and the gasket base through the first grease supply portion, and after the grease is supplied to the contact portion between the elastic component and the protrusion through the second grease supply portion, the tip portion of the worm is embedded in the gasket and arranged radially inward of the bracket.

[0039] Effects of the Invention

[0040] According to a worm reducer and an assembly method thereof in one embodiment of the present invention, when the rotation direction of the worm changes, the tip end portion of the worm can be less likely to displace in a third direction that is orthogonal to both the force direction of the tip end portion, i.e., the first direction, and the axial direction of the worm housing, i.e., the second direction, and the assembly operation can be performed with good workability. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a diagram showing an electric power steering system incorporating a worm speed reducer according to a first example of an embodiment of the present disclosure.

[0042] Figure 2 This is a diagram showing a portion of an electric power steering system incorporating a worm speed reducer according to a first example of an embodiment of the present disclosure.

[0043] Figure 3 yes Figure 2 AA cross-sectional view.

[0044] Figure 4 The housing is omitted and shown Figure 3 Magnified image of the upper right part.

[0045] Figure 5 It is a perspective view showing the distal end portion of the worm and components arranged around it.

[0046] Figure 6 This is a perspective view showing the distal end portion of the worm and components arranged around it in an exploded manner.

[0047] Figure 7 It is from Figure 4 The right side of the diagram.

[0048] Figure 8 It is from Figure 7 The left side of the diagram.

[0049] Figure 9 It is from Figure 7 Figure viewed from the upper side.

[0050] Figure 10 yes Figure 7 BB cross-sectional view.

[0051] Figure 11 yes Figure 10 A partial enlarged view of .

[0052] Figure 12 (a) is a stereoscopic view showing the bracket removed. Figure 12 (b) is from Figure 12 (a) Stereoscopic images observed from different directions.

[0053] Figure 13 (a) is to remove the stent and Figure 4 The right side of the diagram, Figure 13 (b) is from Figure 13 (a) is a diagram of the bracket viewed from the left side. Figure 13 (c) is from Figure 13 (a) is a diagram of the bracket viewed from above. Figure 13 (d) is from Figure 13 (a) the back side ( Figure 4 ) Observe the diagram of the bracket.

[0054] Figure 14 (a) is a perspective view showing the liner removed. Figure 14 (b) is from Figure 14 (a) Stereoscopic images observed from different directions.

[0055] Figure 15 (a) is to remove the liner and Figure 4 The right side of the diagram, Figure 15 (b) is from Figure 15 (a) is a diagram of the pad viewed from the left side. Figure 15 (c) is from Figure 15 (a) is a diagram of the pad viewed from above. Figure 15 (d) is from Figure 15 (a) the back side ( Figure 4 Observe the image of the pad on the left side).

[0056] Figure 16 It is from Figure 4 Figure 2 shows the combination of the bracket and the gasket as seen on the left.

[0057] Figure 17 is to remove the elastic component and Figure 4 The right side of the diagram.

[0058] Figure 18 It is a partially enlarged cross-sectional view showing a state in which grease is filled into the inner side of the worm housing portion.

[0059] Figure 19 (a) to (d) are figures showing the elastic component taken out of the second example of the embodiment of the present disclosure, (a) is a figure observed from one side of the third direction, (b) is a figure observed from the second direction, (c) is a figure observed from the other side of the third direction, and (d) is a figure observed from the first direction.

[0060] Figure 20 (a) to (c) are diagrams showing a state where elastic members are laminated, (a) is a perspective view, (b) is a view viewed from a first direction, and (c) is a view viewed from one side in a third direction.

[0061] Figure 21 This is a comparison example for the second example. Figure 19 Same picture.

[0062] Figure 22 This is a comparison example for the second example. Figure 20 Same picture.

[0063] Figure 23 This is a cross-sectional view showing an example of a conventional structure of a worm speed reducer. DETAILED DESCRIPTION

[0064] [First example]

[0065] use Figures 1 to 18 The first example of an embodiment of the present disclosure is described. Furthermore, this example describes a case where a worm reducer according to one embodiment of the present disclosure is applied to a pinion-assisted electric power steering system. However, the worm reducer according to one embodiment of the present disclosure can be widely applied to column-assisted and double-pinion electric power steering systems, as well as worm reducers incorporated into various mechanical devices other than electric power steering systems.

[0066] Figure 1 The pinion-assisted electric power steering system 1 is shown, incorporating the worm reducer 14 of this embodiment. The electric power steering system 1 includes a steering wheel 2, a steering shaft 3, a steering column 4, a pair of universal joints 5a and 5b, an intermediate shaft 6, a steering gear unit 7, and an electric assist device 8.

[0067] The steering wheel 2 is fixedly supported on the rear end of the steering shaft 3. The steering shaft 3 is rotatably supported inside a steering column 4 supported by the vehicle body. The front end of the steering shaft 3 is connected to the pinion shaft 9 of the steering gear unit 7 via a rear universal joint 5a, an intermediate shaft 6, and a front universal joint 5b. Therefore, when the driver turns the steering wheel 2, the rotation of the steering wheel 2 is transmitted to the pinion shaft 9 via the steering shaft 3, a pair of universal joints 5a and 5b, and the intermediate shaft 6. The rotation of the pinion shaft 9 is converted into linear motion of the rack shaft 10 of the steering gear unit 7, which meshes with the pinion shaft 9. As a result, a steering angle corresponding to the amount of rotation of the steering wheel 2 is applied to the pair of steering wheels. The electric assist device 8 applies auxiliary power generated by the electric motor 15 to the pinion shaft 9. This reduces the force required by the driver to turn the steering wheel 2.

[0068] The steering gear unit 7 includes a housing 11 supported and fixed to the vehicle body, a rack shaft 10, and a pinion shaft 9. The housing 11 includes a rack housing portion 12 extending in the vehicle width direction and an axial side portion ( Figure 1 The center axis of the pinion housing portion 13 is located in a position twisted relative to the center axis of the rack housing portion 12. The internal space of the pinion housing portion 13 is connected to the internal space of the rack housing portion 12. The rack shaft 10 is supported on the inner side of the rack housing portion 12 in a manner that can only move in the axial direction (vehicle width direction). The pinion shaft 9 is supported on the inner side of the pinion housing portion 13 in a manner that can only rotate. The pinion shaft 9 is arranged in the front half (not shown) on the inner side of the pinion housing portion 13. Figure 2 The outer peripheral surface of the lower half of the pinion shaft 9 has pinion teeth. Figure 2The rack shaft 10 is located on the inner side of the rack housing 12 and is connected to the front universal joint 5b. Figure 1 A circumferential portion of the outer peripheral surface (the right side in the middle) has rack teeth that mesh with the pinion teeth of the pinion shaft 9.

[0069] The electric assist device 8 includes a worm speed reducer 14 and an electric motor 15 . The electric assist device 8 is configured such that the rotation of the electric motor 15 is reduced in speed by the worm speed reducer 14 and the rotation is transmitted to the pinion shaft 9 .

[0070] The worm speed reducer 14 includes a housing 16 , a worm wheel 17 , a worm 18 , a bracket 19 , a spacer 20 , and an elastic member 21 .

[0071] The housing 16 includes a worm wheel housing portion 22 and a worm housing portion 23 . The worm housing portion 23 is arranged at a position twisted relative to the worm wheel housing portion 22 and has an axially intermediate portion open to the worm wheel housing portion 22 .

[0072] That is, the central axis of the worm wheel housing portion 22 and the central axis of the worm housing portion 23 are arranged in a position twisted with each other. In addition, the axial middle portion of the worm housing portion 23 is integrally connected to a circumferential point of the radial outer end portion of the worm wheel housing portion 22, and the internal space of the worm housing portion 23 is connected to the internal space of the worm wheel housing portion 22 through the connected portion. In this example, the worm housing portion 23 is configured as a bottomed cylindrical shape. Specifically, the axial end ( Figure 3 The right end in the middle) is closed, and the axial base end ( Figure 3 (left end) opening in the middle.

[0073] In this example, the worm gear housing 22 is coaxially and integrally connected to the axially intermediate portion of the pinion gear housing 13 of the housing 11 constituting the steering gear unit 7. The interior space of the worm gear housing 22 communicates with the interior space of the pinion gear housing 13.

[0074] The worm wheel 17 has gear teeth 24 on its outer peripheral surface and is rotatably supported inside the worm wheel housing portion 22. In this example, the worm wheel 17 is externally fitted and fixed to the axially intermediate portion of the pinion shaft 9.

[0075] The worm 18 has worm teeth 25 meshing with the gear teeth 24 at an axially intermediate portion of its outer peripheral surface, and is rotatably supported inside the worm housing portion 23 .

[0076] In this example, the base end portion ( Figure 3 The left end portion in the middle is supported so as to be slightly swingable relative to the worm housing portion 23 and is connected to the output shaft 27 of the electric motor 15 in a torque-transmittable manner.

[0077] Therefore, in this example, the worm 18 has an internal spline portion 26 on the inner circumferential surface of the base end portion. The electric motor 15 is fixed to the axial base end portion of the worm housing portion 23 by screw fastening, with the output shaft 27 and the worm housing portion 23 arranged coaxially. The internal spline portion 26 of the worm 18 is spline-engaged with the external spline portion 28 provided on the outer circumferential surface of the output shaft 27 of the electric motor 15. As a result, the base end portion of the worm 18 and the output shaft 27 of the electric motor 15 are connected in a manner that allows torque transmission and allows the worm 18 to be slightly swung and displaced. In addition, the base end portion of the worm 18 is supported by a ball bearing 29 having a radial clearance so that it can be slightly swung and displaced relative to the worm housing portion 23.

[0078] In this example, the outer peripheral surface of the distal end of the worm 18 is formed of a stepped cylindrical surface. Specifically, the distal end of the worm 18 includes a small-diameter cylindrical surface portion 30 and a base end portion having a larger diameter cylindrical surface portion 31.

[0079] In this example, a support bearing 32 is positioned between the large-diameter cylindrical surface 31 of the worm 18 and the inner circumferential surface of the worm housing 23. In the illustrated example, the support bearing 32 is constructed from a ball bearing. Specifically, the support bearing 32 comprises an inner ring 33 with an inner raceway on its outer circumference, an outer ring 34 with an outer raceway on its inner circumference, and a plurality of balls 35, each serving as a rolling element, positioned between the inner and outer raceways. However, the support bearing 32 may also be a rolling bearing, such as a cylindrical roller bearing with cylindrical rollers or a tapered roller bearing with tapered rollers, or a sliding bearing.

[0080] In this example, the inner ring 33 is fitted onto the large-diameter cylindrical surface 31 of the worm 18 with a radial gap therebetween. Furthermore, in this example, a cylindrical bushing 36 is disposed between the inner circumferential surface of the inner ring 33 and the large-diameter cylindrical surface 31. Specifically, the inner ring 33 is fitted onto the outer circumferential surface of the bushing 36 with an interference fit, and the bushing 36 is fitted onto the large-diameter cylindrical surface 31 of the worm 18 with a clearance fit. The bushing 36 ensures sliding and / or cushioning properties relative to the outer circumferential surface of the distal end of the worm 18. Such a bushing 36 is preferably made of a material with a low coefficient of friction relative to the metal material constituting the worm 18, such as synthetic resin or a light alloy such as aluminum alloy. However, the bushing 36 may be omitted, or a bushing fitted onto the outer ring 34 with an interference fit may be fitted inside the worm housing 23 with a radial gap therebetween.

[0081] In this example, the outer ring 34 is fitted inside the worm housing 23 with a loose fit. This prevents changes in the preload of the support bearing 32 even when the housing 16 thermally expands during use. However, if thermal expansion of the housing is not a significant concern, the outer ring can be press-fitted into the housing.

[0082] As will be described later, the outer ring 34 is axially held between the bracket 19 disposed inside the worm housing portion 23 and a retainer 37 fitted and fixed inside the worm housing portion 23. The retainer 37 includes a fitting cylindrical portion 38 fitted and fixed to the inner circumference of the worm housing portion 23 in an interference fit manner, and an inward flange portion 39 extending from one axial side ( Figure 3 and Figure 4 In this example, the outer ring 34 is bent radially inwardly along the entire circumference of the right side of the outer ring 34 so that the end surface on one axial side is aligned with the end surface on the other axial side ( Figure 3 and Figure 4 The radially outer portion of the side surface (left side) of the outer ring 34 abuts against the radially outer portion of the side surface, and the side surface on the other axial side abuts against the side surface on one axial side of the inward flange portion 39 via the wave washer 40. This prevents axial displacement of the support bearing 32. However, the wave washer 40 may be omitted, or a wave washer may be disposed between the outer ring 34 and the bracket 19.

[0083] In this example, the distal end of the worm 18 is able to move in a direction of distance relative to the worm wheel 17 and in a first direction (the direction in which the elastic member 21 applies force) based on the radial clearance between the inner circumferential surface of the inner ring 33 and the outer circumferential surface of the distal end of the worm 18, specifically, based on the annular clearance between the inner circumferential surface of the bushing 36 and the large-diameter cylindrical surface portion 31. Figure 3 as well as Figure 4 The displacement in the up and down directions.

[0084] In this example, the support bearing 32 is axially clamped between the bracket 19 and the retainer 37. However, when implementing the worm reducer of one embodiment of the present disclosure, the arrangement of the support bearing is not particularly limited as long as it enables the distal end of the worm to rotate relative to the worm housing and to move forward or backward relative to the worm wheel. For example, a bracket may be embedded and fixed inside the worm housing, and the support bearing may be embedded and retained inside the bracket.

[0085] Furthermore, in the worm reducer 14 of this embodiment, the center axis O17 of the worm wheel 17 and the center axis O18 of the worm 18 (the center axis of the output shaft 27 of the electric motor 15) are perpendicular to each other when viewed from the first direction. However, the present disclosure is also applicable to skew-type worm reducers in which the center axis O17 of the worm wheel 17 and the center axis O18 of the worm 18 (the center axis of the output shaft 27 of the electric motor 15) are obliquely intersecting, that is, forming an acute angle, when viewed from the first direction.

[0086] In the worm reducer 14 of this example, Figures 3 to 10 As shown, a bracket 19, a gasket 20 and an elastic component 21 are arranged between the small-diameter cylindrical surface portion 30 of the worm 18 and the inner circumferential surface of the terminal portion of the worm housing portion 23. The bracket 19 is arranged between the terminal portion of the worm 18 and the worm housing portion 23. In this example, the bracket 19 is arranged on the inner side of the worm housing portion 23 around the terminal portion of the worm 18 in a state where rotation is prevented. The gasket 20 is externally embedded in the terminal portion of the worm 18. In this example, the gasket 20 is externally embedded in the terminal portion of the worm 18 without radial shaking. The elastic component 21 is provided in a manner that is mounted on the protrusion 44 of the bracket 19 and the gasket base 55 of the gasket 20, and is directed to the terminal portion of the worm 18 toward the worm wheel 17 side ( Figure 3 as well as Figure 4 As a result, backlash at the meshing portion between the gear teeth 24 and the worm teeth 25 is suppressed.

[0087] The bracket 19 has a protrusion 44, which includes a first direction and an axial direction of the worm housing portion 23, that is, a second direction ( Figure 3 as well as Figure 4 The third direction ( Figure 3 as well as Figure 4 The two bracket inclined surfaces 41 are two bracket engaging portions provided on the inner side surfaces 51 of the two guide portions 49. The two bracket inclined surfaces 41 are respectively extended in the first direction and are inclined as they move toward one side of the second direction (in this example, Figure 3 and Figure 4 In addition, the bracket 19 is preferably made of a material having sufficient strength and rigidity, such as a metal material, a high-performance resin material such as polyphenylene sulfide (PPS) mixed with glass fiber, or the like.

[0088] More specifically, in this case, Figure 12 (a)~ Figure 13 As shown in (d), the bracket 19 includes: an annular portion 42; a substantially annular side plate portion 43, which extends radially inward from an end portion on one side in the second direction of the annular portion 42; and a protrusion 44, which extends from the radial inner end portion of the side plate portion 43 toward one side in the second direction and has a substantially U-shaped end face shape when viewed from one side in the second direction.

[0089] When viewed from one side in the second direction, the annular portion 42 has a non-circular end surface consisting of a straight portion and an arcuate portion. Specifically, the annular portion 42 has a flat portion 45 at one circumferential position on its outer circumference (in this example, at the end closest to the worm wheel 17 in the first direction). In this example, by fitting the annular portion 42 in a non-circular shape inside the worm housing 23, the bracket 19 is retained inside the worm housing 23 in a rotationally prevented state.

[0090] In this example, if Figure 13 As shown in (d), the inner circumferential surface 46 of the side plate portion 43 has recessed portions 47 on both sides in the third direction. The bottom surface of the recessed portion 47 is formed by a plane perpendicular to the third direction. The portion of the inner circumferential surface 46 of the side plate portion 43 that is offset from the two recessed portions 47, i.e., the two side portions in the first direction, is formed by a cylindrical surface centered on the central axis of the bracket 19.

[0091] In this example, the side surface of the radially outer end portion of the side plate portion 43 on one side in the second direction is aligned with the step portion 48 (see FIG. Figure 3 ) abuts against the bracket 19, thereby preventing the bracket 19 from being displaced to one side in the second direction.

[0092] In this example, the protrusion 44 protrudes from the radially inner end portion of the side plate portion 43, excluding the end portion on the side away from the worm wheel 17 in the first direction, toward one side in the second direction. The protrusion 44 includes two guide portions 49 and a connecting portion 50. The two guide portions 49 constitute the ends of the protrusion 44 on both sides in the third direction. That is, as shown in FIG. Figure 6 、 Figure 12 (a) Figure 13 (a) and Figure 13 As shown in (d), the two guide portions 49 extend toward one side in the second direction from two locations separated in the third direction in the radially inner end portion of the side plate portion 43, specifically, from the same circumferential location as the two recessed portions 47. The two guide portions 49 have a shape extending in the first direction.

[0093] In this example, the end portion of each guide portion 49 on the side away from the worm wheel 17 is located closer to the worm wheel 17 in the first direction than the end portion of the recessed portion 47 on the side away from the worm wheel 17. In other words, when the bracket 19 is viewed from the side in the second direction, the end portion of each recessed portion 47 on the side away from the worm wheel 17 is not covered by the guide portion 49 and is exposed in the second direction.

[0094] The connecting portion 50 constitutes the end portion of the protruding portion 44 that is closer to the worm wheel 17 in the first direction. Specifically, the connecting portion 50 extends from the radially inner end portion of the side plate portion 43 that is closer to the worm wheel 17 in the first direction toward one side in the second direction, and connects the ends of the two guide portions 49 that are closer to the worm wheel 17 in the first direction. The connecting portion 50 has a partially cylindrical shape centered on the central axis of the bracket 19. Furthermore, if the bracket has sufficient strength to prevent deformation of the two guide portions, the connecting portion can be omitted.

[0095] The two bracket inclined surfaces 41 constituting the bracket 19 are provided on the inner side surfaces 51 of the two guide portions 49, which are opposite to each other in the third direction. Figure 13 As shown in (c), the inner side surfaces 51 of the two guide parts 49 each have a crank shape with a stepped surface (bracket inclined surface 41) in the middle part in the second direction. That is, the two bracket inclined surfaces 41 are provided in the middle part in the second direction of the inner side surfaces 51 of the two guide parts 49, more specifically, in the part on one side of the second direction of the middle part. The two bracket inclined surfaces 41 are inclined toward each other as they move toward one side in the second direction. The part of the inner side surfaces 51 of the two guide parts 49 located on the side of the second direction relative to the two bracket inclined surfaces 41 and the part located on the other side of the second direction relative to the two bracket inclined surfaces 41 are respectively composed of planes orthogonal to the third direction. Therefore, the interval between the inner side surfaces 51 of the two guide parts 49 is narrower in the part located on the side of the second direction relative to the two bracket inclined surfaces 41 than in the part located on the other side of the second direction relative to the two bracket inclined surfaces 41.

[0096] In the case of implementing the worm reducer of one embodiment of the present disclosure, the inclination angle φ of the bracket inclined surface 41 relative to the second direction can be set to any value within the range of 0°<φ<90°, but is preferably not less than 20° and not more than 80°, and more preferably not less than 30° and not more than 70°. In this example, the inclination angle φ is set to 30°.

[0097] Furthermore, the two bracket pressed surfaces 52 constituting the bracket 19 are provided on the end surfaces, i.e., the distal end surfaces, on one side in the second direction of the two guide portions 49. In this example, the two bracket pressed surfaces 52 and the end surface, i.e., the distal end surface, on one side in the second direction of the connecting portion 50 are continuous with each other and exist in the same imaginary plane orthogonal to the second direction.

[0098] Furthermore, the bracket 19 has a first grease supply portion 74 for supplying grease to the contact portion P1 between the elastic member 21 and the pad base 55 constituting the pad 20, and has a second grease supply portion 75 for supplying grease to the contact portion P2 between the elastic member 21 and the protrusion 44.

[0099] In this example, first grease supply portion 74 is provided so as to penetrate, in the second direction, a portion of side plate portion 43 constituting bracket 19, whose circumferential phase is substantially aligned with contact portion P1, located radially inward of contact portion P1. Contact portion P1 is the contact portion between elastic member 21 and gasket base 55, more specifically, the contact portion between arm portion 68 of elastic member 21 and pressed portion 62 of gasket base 55. Specifically, in this example, first grease supply portion 74 is formed by an end portion of recessed portion 47 of side plate portion 43, located on the side facing away from worm wheel 17 in the first direction.

[0100] like Figure 13 As shown in (c) and (d), the first grease supply portion 74 is formed by a first wall surface 74a extending parallel to the first direction and the second direction and a pair of second wall surfaces 74b, 74b extending parallel to the second direction and the third direction. The pair of second wall surfaces 74b, 74b are opposite to each other in the first direction. The outer ends of the pair of second wall surfaces 74b, 74b in the third direction are connected to each other through the first wall surface 74a. The first wall surface 74a and the pair of second wall surfaces 74b, 74b are orthogonal to each other and are roughly U-shaped when viewed from the second direction. Figure 13 As shown in (c) and (d), when viewed from the second direction, the pair of second grease supply portions 75, 75 are each formed into a substantially rectangular cross-section that is recessed toward the outside in the third direction. Figure 12 As shown in (a) and (b), the first grease supply portion 74 extends through the bracket 19 in the second direction. The pair of first grease supply portions 74, 74 preferably have substantially the same cross-sectional area as viewed from the second direction. This improves grease fluidity and helps reduce uneven coating.

[0101] In addition, the circumferential phase of the first grease supply portion 74 does not need to be completely consistent with the circumferential phase of the contact portion P1, which is the contact portion between the elastic member 21 and the pressed portion 62. Figure 18 As shown, when grease is filled into the worm housing portion 23 from the base end side (the other side in the second direction) with the bracket 19, the gasket 20, and the elastic member 21 assembled inside the worm housing portion 23, the grease can be slightly staggered as long as the grease can be supplied to the contact portion P1 between the elastic member 21 and the pressed portion 62 by, for example, pressure feeding, via the first grease supply portion 74. Specifically, for example, in a cross section of an imaginary plane perpendicular to the second direction, the angle formed by the straight line connecting the circumferential center position of the first grease supply portion 74 and the central axis O18 of the worm 18 and the straight line connecting the contact portion P1 and the central axis O18 of the worm 18 can be set to within ±10 degrees, preferably within ±5 degrees.

[0102] In the case of a worm reducer according to one embodiment of the present disclosure, a first grease supply portion for supplying grease to the contact portion between the elastic member and the pressed portion can also be provided on the gasket. Specifically, for example, the first grease supply portion can be formed to radially penetrate the portion between the two pressed portions and the base surface portion at the end of the base body on the side farther from the worm wheel in the first direction and the inner circumferential surface of the through hole, and to open on the side surface of the base body on the other side in the second direction.

[0103] In this example, the second grease supply portion 75 is provided radially through a portion of the protrusion 44 that is substantially aligned in phase with the contact portion P2 in the circumferential direction. This contact portion P2 is the contact portion between the elastic member 21 and the protrusion 44, more specifically, the contact portion between the arm portion 68 of the elastic member 21 and the side surface of the connecting portion 50 that constitutes the protrusion 44 that is closer to the worm wheel 17 in the first direction. Specifically, in this example, the second grease supply portion 75 is provided radially through the connection portion between the end portion of the guide portion 49 that is closer to the worm wheel 17 in the first direction and the circumferential end portion of the connecting portion 50. Furthermore, in this example, the second grease supply portion 75 opens on the inner and outer circumferential surfaces of the protrusion 44, as well as on the end surface on one side in the second direction. In other words, the second grease supply portion 75 comprises a groove formed radially along the protrusion 44.

[0104] like Figure 13 As shown in (c) and (d) of FIG, the second grease supply portion 75 is formed by a third wall surface 75a extending parallel to the circumferential direction and the second direction and a pair of fourth wall surfaces 75b, 75b extending parallel to the radial direction and the third direction. Figure 13 As shown in (c) and (d), when viewed from the second direction, the pair of fourth walls 75b, 75b are circumferentially opposed to each other. The radially outer ends of the pair of fourth walls 75b, 75b are connected to each other by the third wall 75a. The third wall 75a and the pair of fourth walls 75b, 75b are orthogonal to each other and form a roughly U-shape when viewed from the second direction. Figure 13 As shown in (c) and (d), when viewed from the second direction, the pair of second grease supply portions 75, 75 are each formed into a substantially rectangular cross-section that is recessed toward the radially outer side. Figure 13 As shown in (a) and (b), the second grease supply portion 75 is a bottomed shape having a bottom surface 75c on the other side in the second direction. The pair of second grease supply portions 75, 75 preferably have approximately the same cross-sectional area as viewed in the second direction. This improves the grease's fluidity, helping to reduce uneven application.

[0105] Furthermore, it is more preferable that the cross-sectional areas viewed from the second direction of the first grease supply portion 74 and the second grease supply portion 75 are substantially the same. In this case, the fluidity of the grease can be further improved.

[0106] In addition, the circumferential phase of the second grease supply portion 75 does not need to be completely consistent with the circumferential phase of the contact portion P2, which is the contact portion between the elastic member 21 and the protrusion 44. Figure 18 As shown, when grease is filled into the worm housing portion 23 from the base end side (the other side in the second direction) with the bracket 19, the gasket 20, and the elastic member 21 assembled inside the worm housing portion 23, the grease can be slightly staggered as long as grease can be supplied to the contact portion P2 between the elastic member 21 and the protrusion 44 via the second grease supply portion 75. Specifically, for example, in a cross section of an imaginary plane perpendicular to the second direction, the angle formed by the straight line connecting the circumferential center of the second grease supply portion 75 and the central axis O18 of the worm 18 and the straight line connecting the contact portion P1 and the central axis O18 of the worm 18 can be set to within ±10 degrees, preferably within ±5 degrees.

[0107] like Figure 6 、 Figure 10 、 Figure 11 as well as Figure 14 (a)~ Figure 15 As shown in (d), the gasket 20 includes two gasket inclined surfaces 53, which are provided on both sides in the third direction and serve as two gasket engaging portions that contact the two bracket inclined surfaces 41; and a gasket elastic pressing portion 76, which elastically presses a portion of the bracket 19 toward the other side in the second direction, thereby applying preload to the contact portion between the two bracket inclined surfaces 41 and the two gasket inclined surfaces 53. In this embodiment, the portion of the bracket 19 pressed by the gasket elastic pressing portion 76 is the protrusion 44 of the bracket 19.

[0108] In this example, the two pad inclined surfaces 53 are in surface contact with the two bracket inclined surfaces 41. Specifically, they are inclined in the same direction and at the same angle as the two bracket inclined surfaces 41 (see FIG. Figure 11 ).

[0109] The pad elastic pressing portion 76 is formed of two pad elastic pressing plates 54. The two pad elastic pressing plates 54 are located on the second direction side relative to the two pad inclined surfaces 53 and extend from the center of the pad 20 in the third direction toward sides separated from each other in the third direction. The two pad elastic pressing plates 54 elastically press the two bracket pressed surfaces 52 constituting the bracket 19 toward the other side in the second direction.

[0110] The liner 20 is preferably made of a material having a low friction coefficient with respect to the metal material constituting the worm 18 , that is, a light alloy such as synthetic resin or aluminum alloy.

[0111] In this example, the gasket 20 has a gasket base 55 arranged between the two guide portions 49 and a through hole 56 that passes through the gasket base 55 along the second direction and for the distal end portion of the worm 18 to be inserted therethrough, and two gasket inclined surfaces 53 are provided on the side surfaces on both sides of the third direction of the gasket base 55, and a flat plate portion 57 including two gasket elastic pressing plates 54 is connected to a portion of the gasket base 55 that protrudes from between the two guide portions 49 to one side in the second direction.

[0112] The pad base 55 includes a base body 58 and two base extensions 59 .

[0113] The base body 58 extends in the first direction and has a generally rectangular end surface. The through-hole 56 extends through the base body 58 in the second direction, extending through the half of the base body 58 on the side closest to the worm wheel 17 in the first direction. In this example, the through-hole 56 is a stepped hole having an oblong hole portion 60 on one side in the second direction and a circular hole portion 61 on the other side in the second direction. The circular hole portion 61 has an inner diameter slightly larger than the outer diameter of the small-diameter cylindrical surface portion 30 of the worm 18.

[0114] In addition, the base body 58 has two pressed portions 62 at the end portion on the side away from the worm wheel 17 in the first direction and at the end portions on both sides of the third direction in the other side portion in the second direction. The two pressed portions 62 are respectively composed of a partial cylindrical surface centered on the central axis of the through hole 56. However, in the case of a worm reducer in accordance with one embodiment of the present invention, the base body can also be constructed to have a pressed portion at a position at the end portion on the side away from the worm wheel in the first direction. In this example, the base body 58 has a base surface portion 63 composed of a flat surface orthogonal to the first direction at the end portion on the side away from the worm wheel 17 in the first direction and at the portion between the two pressed portions 62 in the third direction.

[0115] The two base extensions 59 protrude from a portion of the other half of the base body 58 in the second direction that is closer to the worm wheel 17 in the first direction toward a side separated from each other in the third direction. The two base extensions 59 are respectively extended in the first direction.

[0116] In this example, the two pad inclined surfaces 53 constituting the pad 20 are provided on the side surfaces of the two base extensions 59 on one side in the second direction. The two pad inclined surfaces 53 are inclined toward each other as they approach one side in the second direction. The inclination angle φ of the pad inclined surfaces 53 with respect to the second direction is the same as the inclination angle φ of the bracket inclined surface 41 with respect to the second direction.

[0117] In addition, in this example, Figure 16 As shown, by inserting the gasket base 55 between the two guide portions 49, the dimensions of each base extension 59 in the first direction are adjusted so that the first grease supply portion 74 of the bracket 19 is not blocked by the two base extension portions 59 when the bracket 19 and the gasket 20 are combined. In other words, when the bracket 19 and the gasket 20 are combined, the first grease supply portion 74 is located farther from the worm wheel 17 than the base extension portion 59 in the first direction.

[0118] The flat plate portion 57 is integrally connected to the end portion on one side of the base body 58 in the second direction, and has a circular outer peripheral shape when viewed from the side in the second direction. The through hole 56 penetrates the radial center portion of the flat plate portion 57 in the second direction. Therefore, the flat plate portion 57 is configured as an annular flat plate centered on the central axis of the through hole 56. The outer diameter of the flat plate portion 57 is larger than the width of the base body 58 in the third direction. The ends on both sides of the flat plate portion 57 in the third direction extend further than the base body 58 to both sides in the third direction. The end portion of the flat plate portion 57 on the side closer to the worm wheel 17 in the first direction extends further than the base body 58 to the side closer to the worm wheel 17 in the first direction. The end portion of the base body 58 on the side farther from the worm wheel 17 in the first direction extends further than the flat plate portion 57 to the side farther from the worm wheel 17 in the first direction.

[0119] In this example, the two elastic pad pressing plates 54 constituting the pad 20 are connected to a portion of the pad base 55 that protrudes in the second direction from between the two guide portions 49. Specifically, the two elastic pad pressing plates 54 are formed by the end portions of the flat plate portion 57 on both sides in the third direction.

[0120] In this example, if Figure 10 、 Figure 11 、 Figure 14 (b) and Figure 15 (b)~ Figure 15 As shown in (d), the two liner elastic pressing plates 54 each have at least one protrusion 64a, 64b extending in the first direction on the side surface on the other side in the second direction. In the free state before the two liner elastic pressing plates 54 are elastically deformed, in other words, in the free state before the liner 20 is assembled to the protrusion 44 of the bracket 19, the height of at least one protrusion 64a, 64b in the second direction increases continuously or stepwise as it moves away from the worm 18 in the third direction.

[0121] In this example, at least one protrusion 64a, 64b is composed of two protrusions 64a, 64b that are separated from each other in the third direction. Figure 15As shown in (a), in the free state, the protrusion 64a on the side farther from the worm 18 in the third direction is higher in the second direction than the protrusion 64b on the side closer to the worm 18 in the third direction. In this example, in the free state, the cross-sectional shape of the distal end of each of the two protrusions 64a and 64b is a straight line perpendicular to the second direction. More specifically, in the free state, the distal end of each of the two protrusions 64a and 64b is formed by a flat surface perpendicular to the second direction.

[0122] It should be noted that the degree to which the height in the second direction of the protrusion 64a on the side away from the worm 18 in the third direction is higher than the height in the second direction of the protrusion 64b on the side close to the worm 18 in the third direction is not particularly limited as long as the respective end portions of the protrusions 64a and 64b can abut against the pressed surface 52 of the bracket when the gasket 20 is assembled to the protrusion 44 of the bracket 19. However, in the worm reducer 14 assembled in the electric power steering device 1, it can be set to, for example, not less than 0.05 mm and not more than 0.30 mm, and preferably not less than 0.10 mm and not more than 0.15 mm.

[0123] In this example, the two liner elastic pressing plates 54 each have a slit 65 extending in the first direction and extending through the second direction at the base end portion, i.e., the end portion located at the center of the liner 20 in the third direction. In this example, the flexural rigidity in the second direction of the base end portion of the liner elastic pressing plate 54 adjacent to both sides of the slit 65 in the longitudinal direction is adjusted by appropriately controlling the width and length of the slit 65 and the thickness of the liner elastic pressing plate 54. However, in the case of a worm reducer according to one embodiment of the present disclosure, the slit can be omitted.

[0124] like Figures 3 to 5 as well as Figures 7 to 10 As shown, the washer 20 is assembled to the protruding portion 44 of the bracket 19 and is externally embedded in the distal end of the worm 18 .

[0125] Specifically, with the portion of the gasket base 55 of the gasket 20 located closer to the worm wheel 17 in the first direction positioned between the two guide portions 49 forming the protrusion 44 of the bracket 19, the two gasket inclined surfaces 53 come into surface contact with the two bracket inclined surfaces 41. Furthermore, the distal ends of the protrusions 64a and 64b of the two gasket elastic pressing plates 54 elastically press the two bracket pressed surfaces 52 toward the other side in the second direction. This applies preload to the contact areas between the two bracket inclined surfaces 41 and the two gasket inclined surfaces 53.

[0126] The inclination angle α of each of the two pad elastic pressing plates 54 with respect to the imaginary plane orthogonal to the second direction when the pad 20 is assembled to the protruding portion of the bracket 19 is not particularly limited and can be set to, for example, 0 degrees or more and 15 degrees or less.

[0127] The small-diameter cylindrical surface portion 30 of the distal end portion of the worm 18 is fitted into the circular hole portion 61 of the through hole 56 of the spacer 20 so as to be relatively rotatable without being loose in the radial direction.

[0128] In this state, a gap in the first direction exists between a side surface of the gasket base portion 55 of the gasket 20 that is closer to the worm wheel 17 in the first direction and a side surface of the connecting portion 50 that constitutes the protrusion 44 of the bracket 19 that is farther from the worm wheel 17 in the first direction. In this example, the gasket 20 is displaceable in the first direction relative to the bracket 19 due to this gap in the first direction.

[0129] In addition, in this state, Figure 10 and Figure 11 As shown, gaps in the third direction exist between the inner side surfaces 51 of the two guide portions 49 located on the second direction side relative to the two bracket inclined surfaces 41 and the inner side surfaces 51 of the two guide portions 49 located on the other second direction side relative to the two bracket inclined surfaces 41 and the pad base 55 of the pad 20. In this example, the pad 20 can be displaced in the third direction relative to the bracket 19 due to the gaps in the third direction.

[0130] In this example, the elastic member 21 is composed of a leaf spring. More specifically, in this example, Figure 6 as well as Figure 17 As shown, the elastic member 21 is composed of a cylindrical leaf spring having a discontinuous portion 66 at one circumferential point. Specifically, the elastic member 21 includes a base portion 67 located farther from the worm 18 in the first direction, and two arms 68 extending circumferentially from both circumferential ends of the base portion 67.

[0131] In this example, the base portion 67 is formed of a flat plate perpendicular to the first direction.

[0132] The two arm portions 68 are each configured in a partial cylindrical shape and each have a bent portion 69 bent radially outward from a distal end portion.

[0133] However, when implementing the worm reducer according to one embodiment of the present disclosure, the elastic member may have any configuration as long as it can elastically bias the spacer toward the worm wheel 17 in the first direction. For example, if the elastic member is formed of a leaf spring, it may have a shape other than a notched cylinder. Alternatively, the elastic member may be formed of a torsion coil spring.

[0134] The elastic member 21 is assembled to the bracket 19 by being externally fitted over the liner base 55 of the gasket 20 and the protrusion 44 of the bracket 19. In this example, with the gasket base 55 of the gasket 20 and the protrusion 44 of the bracket 19 inserted radially inward of the elastic member 21, the base 67 of the elastic member 21 abuts against the base surface 63 of the gasket 20. The inner circumferential surfaces of the proximal ends of the two arm portions 68 are elastically pressed against the two pressed portions 62 of the gasket base 55. Furthermore, the inner circumferential surfaces of the distal ends of the two arm portions 68 are elastically pressed against the side surface of the connecting portion 50 constituting the protrusion 44 of the bracket 19, which is closer to the worm wheel 17 in the first direction. This elastically biases the distal end of the worm 18 toward the worm wheel 17, that is, toward the side closer to the worm wheel 17 in the first direction, via the gasket 20. This reduces backlash at the meshing portion between the gear teeth 24 and the worm teeth 25.

[0135] Furthermore, the contact portion P1 between the elastic member 21 and the pad base portion 55 (pressed portion 62 ), and the contact portion P2 between the elastic member 21 and the protrusion 44 are lubricated with grease.

[0136] When assembling the worm reducer 14 of this example, the liner base 55 of the liner 20 is first assembled to the protrusion 44 of the bracket 19. The elastic member 21 is then assembled to the bracket 19 so that the elastic member 21 fits over the liner base 55 and the protrusion 44. This results in an assembly of the bracket 19, liner 20, and elastic member 21. This assembly is then positioned at a predetermined location inside the worm housing 23. Furthermore, the support bearing 32, bushing 36, wave washer 40, and retainer 37 are positioned at predetermined locations inside the worm housing 23.

[0137] Then, if Figure 18 As shown, grease G is filled from the base end side (the other side in the second direction) of the worm housing portion 23 to the inner side of the worm housing portion 23. Furthermore, when the grease G is filled radially inward of the bracket 19, a portion of the grease G is supplied to the contact portion P1 between the elastic member 21 and the gasket base 55 via the first grease supply portion 74, and is supplied to the contact portion P2 between the elastic member 21 and the protrusion 44 via the second grease supply portion 75.

[0138] Thereafter, the worm 18 is inserted into the inner side of the worm housing portion 23 from the base end side of the worm housing portion 23, the small-diameter cylindrical surface portion 30 is embedded in the circular hole portion 61 of the liner 20, and the large-diameter cylindrical surface portion 31 is embedded in the bushing 36, and the worm teeth 25 are meshed with the gear teeth 24 of the worm wheel 17 which is rotatably supported on the inner side of the worm wheel housing portion 22.

[0139] Furthermore, the order of assembling the worm speed reducer 14 can be appropriately changed or performed simultaneously as long as no contradiction occurs.

[0140] According to the worm speed reducer 14 of this example, the following effects can be achieved.

[0141] The two pad inclined surfaces 53 constituting the pad 20 are in surface contact with the two bracket inclined surfaces 41 constituting the bracket 19. Furthermore, the distal ends of the protrusions 64a and 64b of the two pad elastic pressing plates 54 constituting the pad 20 elastically press the two bracket pressed surfaces 52 constituting the bracket 19 toward the other side in the second direction. This applies a preload to the contact areas between the two bracket inclined surfaces 41 and the two pad inclined surfaces 53. Therefore, the contact between the two bracket inclined surfaces 41 and the two pad inclined surfaces 53 restricts displacement of the pad 20 relative to the bracket 19 in the third direction, preventing the pad 20 from unresistance-free shaking relative to the bracket 19 in the third direction.

[0142] Specifically, in this case, Figure 10 and Figure 11 As shown, the distal ends of the protrusions 64a and 64b of the pad elastic pressing plate 54 elastically press the bracket pressed surface 52 toward the other side in the second direction. This results in an elastic force (preload) Fp acting toward one side in the second direction from the pad inclined surface 53 on the bracket inclined surface 41. This elastic force Fp is then converted into an elastic force (preload) Fx acting outward in the third direction from the pad inclined surface 53 on the bracket inclined surface 41. In this example, this elastic force Fx prevents the pad 20 from unresistance-free shaking relative to the bracket 19 in the third direction.

[0143] Therefore, even if the direction of the component in the third direction of the reaction force applied from the gear teeth 24 to the worm teeth 25 changes due to a change in the rotational direction of the worm 18, the distal end of the worm 18 is less likely to shift in the third direction. As a result, it is possible to prevent abnormal noises such as rattling sounds from occurring at the meshing portion between the gear teeth 24 and the worm teeth 25, or abnormal noises such as collision sounds from occurring between the gasket 20 and the bracket 19.

[0144] When implementing the worm reducer according to one embodiment of the present disclosure, the bending rigidity in the second direction of the portion of the base end of the elastically pressing pad 54 adjacent to both sides of the longitudinal direction of the slit 65 can be varied by changing the width and length of the slit 65, the thickness of the elastically pressing pad 54, the height of the protrusions 64a and 64b in the second direction, and so on. This allows the magnitude of the force with which the distal ends of the protrusions 64a and 64b of the elastically pressing pad 54 elastically press the bracket's pressed surface 52 toward the other side in the second direction to be varied. Consequently, the magnitude of the elastic force Fp can be arbitrarily varied.

[0145] The pad elastic pressing plate 54 locally presses the holder pressed surface 52 with the distal ends of the protrusions 64a and 64b. Therefore, the pressing force can be stabilized compared to a case where the pad elastic pressing plate presses the holder pressed surface over a wider area.

[0146] Between the elastic force Fx and the elastic force Fp, the relationship "Fx = Fp / tanφ" holds. In this example, the inclination angle φ = 30°, so Fx = Fp / tan30° = 1.7Fp. That is, the elastic force Fx is greater than the elastic force Fp. In the case of a worm reducer that implements one embodiment of the present invention, the size of the elastic force Fx can be arbitrarily changed not only by changing the size of Fp, but also by changing the size of the inclination angle φ. For example, if φ = 45°, Fx = Fp can be made, if 45° < φ < 90°, Fx < Fp can be made, and if 0° < φ < 45°, Fx > Fp can be made. In addition, by changing the inclination angle φ without changing the material of the gasket 20 (based on the elastic force of the material), the size of the elastic force Fx can be adjusted. Therefore, the size of the elastic force Fx can be easily adjusted in the design stage.

[0147] Furthermore, in the case of a worm reducer according to one embodiment of the present disclosure, the inclination angle of the bracket inclined surface 41 relative to the second direction and the inclination angle of the pad inclined surface 53 relative to the second direction do not need to be strictly the same, and may be different within the range of manufacturing error. In addition, the inclination angle of the bracket inclined surface 41 relative to the second direction may be slightly smaller (for example, about 0.5°) than the inclination angle of the pad inclined surface 53 relative to the second direction. In this way, in the contact portion between the bracket inclined surface 41 and the pad inclined surface 53, the end portion of the pad inclined surface 53 ( Figure 11 The right end of the third direction, Figure 11 The end portion on the other side of the second direction in FIG. 4 is in particularly strong contact with the support inclined surface 41. As a result, the posture of the pad 20 relative to the support 19 is stabilized.

[0148] In addition, when viewed from the first direction, Figure 10 and Figure 11 As shown, consider that from the neutral state in which the central axis of the bracket 19 and the central axis of the pad 20 are aligned with each other, the pad 20 is moved to either side in the third direction relative to the bracket 19, for example Figure 10 and Figure 11In this case, as the right side displacement of the pad 20 is carried out along the right side displacement of the bracket 41, the pad base 55 of the pad 20 is displaced toward the other side in the second direction, and at the same time, the right side pad elastic pressing plate 54 is elastically deformed in the second direction in a manner of leaning to one side. Moreover, the elastic pressing force of the right side pad elastic pressing plate 54 on the right side of the bracket pressed surface 52 increases by an amount corresponding to the amount of the elastic deformation, and accordingly, the elastic forces Fp and Fx increase. As a result, it becomes less likely for the pad 20 to displace toward the right side. For the displacement of the pad 20 from the neutral state relative to the bracket 19 to the Figure 10 and Figure 11 The same is true for the left displacement in .

[0149] The inner circumferential surface of the circumferential center portion of the elastic member 21 elastically presses against two pressed portions 62 provided at the ends in the third direction of the base body 58 of the gasket 20. Consequently, the two pressed portions 62 are subjected to not only a force component in the first direction approaching the worm wheel 17 but also a force component in the third direction opposite thereto. This also prevents the distal end of the worm 18 from displacing in the third direction when the rotational direction of the worm 18 changes.

[0150] In addition, in this example, the bracket 19 has a first grease supply portion 74 for supplying grease to the contact portion P1 near the contact portion P1 between the elastic member 21 and the pad base 55 constituting the pad 20, and has a second grease supply portion 75 for supplying grease to the contact portion P2 near the contact portion P2 between the elastic member 21 and the protrusion 44.

[0151] Therefore, when assembling the worm reducer 14 of this example, Figure 18 As shown, after the bracket 19, the gasket 20 and the elastic component 21 are assembled on the inner side of the worm housing portion 23, even when grease G is filled into the inner side of the worm housing portion 23 from the base end side (the other side of the second direction), a sufficient amount of grease G can be supplied to the contact portion P1 between the elastic component 21 and the gasket base 55 (pressed portion 62), and the contact portion P2 between the elastic component 21 and the protrusion 44.

[0152] That is, inside the worm housing portion 23, grease G filled from the base end side can be supplied to the contact portion P1 between the elastic member 21 and the gasket base 55 via the first grease supply portion 74, and grease G filled from the base end side can be supplied to the contact portion P2 between the elastic member 21 and the protrusion 44 via the second grease supply portion 75. This ensures that the lubrication conditions at the contact portion P1 between the elastic member 21 and the gasket base 55 and the contact portion P2 between the elastic member 21 and the protrusion 44 are improved, thereby preventing wear at these contact portions P1 and P2.

[0153] Alternatively, a method may be considered in which, before arranging the bracket, gasket, and elastic member inside the worm housing, grease is applied to the contact portion between the elastic member and the gasket base, and the contact portion between the elastic member and the protrusion, respectively, during assembly of the worm reducer. Thereafter, the bracket, gasket, and elastic member are arranged inside the worm housing. However, in this case, since the surface of the assembly consisting of the bracket, gasket, and elastic member is coated with adhesive grease before assembly inside the worm housing, there is a possibility that the operability of the assembly will be impaired, foreign matter such as dust will easily adhere, and management will be complicated.

[0154] In contrast, the worm reducer 14 of this embodiment includes the first grease supply portion 74 and the second grease supply portion 75. Therefore, even when grease is applied to the interior of the worm housing 23 after the bracket 19, gasket 20, and elastic member 21 are assembled inside the worm housing 23, a sufficient amount of grease G can be supplied to the contact portion P1 between the elastic member 21 and the gasket base 55, and the contact portion P2 between the elastic member 21 and the protrusion 44. In other words, when assembling the worm reducer 14, it is no longer necessary to apply grease to the contact portions P1 and P2 before the bracket 19, gasket 20, and elastic member 21 are positioned inside the worm housing. This prevents deterioration in the operability of the assembly of the bracket 19, gasket 20, and elastic member 21, and prevents cumbersome maintenance, thereby improving the workability of the worm reducer 14 assembly.

[0155] In this example, one side in the third direction ( Figure 13 On the left side of (a), Figure 13 The first grease supply portion 74 on the right side of (c) and the other side of the third direction in the two second grease supply portions 75 ( Figure 13 On the right side of (a), Figure 13The second grease supply portion 75 (on the left side of (c)) is located on the radially opposite side (on the diagonal line) relative to the center axis of the bracket 19. In addition, the first grease supply portion 74 on the other side in the third direction of the two first grease supply portions 74 and the second grease supply portion 75 on one side in the third direction of the two second grease supply portions 75 are located on the radially opposite side (on the diagonal line) relative to the center axis of the bracket 19. Therefore, according to the worm reducer 14 of this example, compared with a structure in which the grease supply portion for supplying grease to the contact portion between the bracket and the elastic component is provided only on one side portion close to the worm wheel in the first direction or on one side portion away from the worm wheel, when grease is supplied from the other side portion to the one side portion of the bracket 19 in the second direction through the first grease supply portion 74 and the second grease supply portion 75, the flow of grease can be stabilized. Therefore, the productivity of the worm reducer 14 can be improved, and mass production can be easily achieved.

[0156] Furthermore, when implementing the worm reducer according to one embodiment of the present disclosure, the positions of the first and second grease supply portions are not limited to those of this embodiment and can be modified as appropriate, as long as they can supply a sufficient amount of grease G to the contact portion between the elastic member and the pad base, and to the contact portion between the elastic member and the protrusion. For example, the second grease supply portion may be formed so as to penetrate the side plate portion constituting the bracket in the second direction.

[0157] Furthermore, in this example, in the free state before the two elastic spacer pressing plates 54 are elastically deformed, the height of at least one protrusion 64a, 64b, respectively, in the second direction increases continuously or in stages as the protrusion 64a, 64b, located farther from the worm 18 in the third direction, increases in height. Specifically, the height of the protrusion 64a, located farther from the worm 18 in the third direction, in the second direction, is greater than the height of the protrusion 64b, located closer to the worm 18 in the third direction. This ensures that the distal end of the worm 18 is reliably prevented from displacing in the third direction when the rotational direction of the worm 18 changes.

[0158] By assembling the gasket 20 to the protrusion 44 of the bracket 19, if the terminal ends of the protrusions 64a and 64b of the two gasket elastic pressing plates 54 are elastically abutted against the two bracket pressed surfaces 52 of the bracket 19, the two gasket elastic pressing plates 54 are elastically deformed with their respective base ends as the center, in a manner such that they tilt toward the side of the second direction as they move away from the worm gear 18 in the third direction.

[0159] If the heights of the two protrusions in the second direction of the two elastic liner pressing plates are equal, when the liner is assembled to the protruding portion of the bracket, it is possible that only the distal end of the protrusion on the side closer to the worm in the third direction will contact the bracket's pressed surface, while the distal end of the protrusion on the side farther from the worm in the third direction will not contact the bracket's pressed surface. Consequently, the elastic deformation of the liner elastic pressing plates may not be stabilized, or the surface pressure at the contact portion between the distal end of the protrusion on the side closer to the worm in the third direction and the bracket's pressed surface may be excessive, causing wear at this contact portion. Consequently, the elastic forces Fx and Fp, which are generated by the distal end of the protrusion elastically pressing the bracket's pressed surface toward the other side in the second direction, may not be stabilized.

[0160] In contrast, in this example, the height of the protrusion 64a on the side farther from the worm 18 in the third direction in the second direction is greater than the height of the protrusion 64b on the side closer to the worm 18 in the third direction in the second direction. Therefore, when the gasket 20 is assembled to the protrusion 44 of the bracket 19, the distal ends of the two protrusions 64a and 64b can reliably abut the bracket pressed surface 52. This stabilizes the elastic deformation of the gasket elastic pressing plate 54, prevents excessive surface pressure at the contact area between the distal ends of the protrusions 64a and 64b and the bracket pressed surface 52, and prevents wear at this contact area. As a result, the elastic forces Fx and Fp, which elastically press the bracket pressed surface 52 toward the other side in the second direction by the distal ends of the protrusions 64a and 64b, are stabilized, stably preventing the distal end of the worm 18 from displacing in the third direction when the rotational direction of the worm 18 changes.

[0161] Furthermore, according to the worm reducer 14 of this embodiment, grease for lubricating the contact areas between the distal ends of the protrusions 64a and 64b and the bracket pressed surface 52 can be retained between the two protrusions 64a and 64b provided on each of the two spacer elastic pressing plates 54. Consequently, the lubrication of the contact areas between the distal ends of the protrusions 64a and 64b and the bracket pressed surface 52 can be maintained well over a long period of time. This also prevents wear at the contact areas between the distal ends of the protrusions 64a and 64b and the bracket pressed surface 52.

[0162] Furthermore, in this example, the number of protrusions 64a and 64b on each of the two elastic liner pressing plates 54 is set to two. However, in the case of a worm reducer according to one embodiment of the present disclosure, the number of protrusions on each of the two elastic liner pressing plates can be set to three or more, or even one. When the number of protrusions on each of the two elastic liner pressing plates is set to one, the distal end of the protrusion is formed by an inclined surface that tilts toward the other side of the second direction as it moves away from the worm in the third direction. This increases the contact area between the distal end of the protrusion and the pressed surface of the bracket, thereby preventing the elastic deformation of the elastic liner pressing plates from becoming unstable or the distal end of the protrusion from wearing out.

[0163] [Second example]

[0164] use Figure 19 (a)~ Figure 20 (c) The second example of the embodiment of the present disclosure is described. The structure of the elastic member 21a of the worm reducer of this example is different from that of the worm reducer 14 of the first example. The structure and effects of other parts are the same as those of the worm reducer 14 of the first example, so the description is omitted.

[0165] like Figure 19 (a)~ Figure 19 As shown in (d), the elastic member 21a is formed of a leaf spring having a cylindrical shape (roughly C-shaped) and a discontinuous portion 66 at one point in the circumferential direction. In this example, the elastic member 21a includes a base portion 67a located farther from the worm 18 in the first direction, and two arm portions 68a extending circumferentially from both circumferential ends of the base portion 67a.

[0166] In this example, the base 67a is formed of a flat plate perpendicular to the first direction. The base 67a has a constricted portion 70 in the middle portion in the third direction. The constricted portion 70 has a smaller width in the second direction than the width of the two side portions in the third direction. However, the constricted portion 70 may be omitted.

[0167] The two arms 68a are each partially cylindrical. In this example, each arm 68a includes, in order from the side closest to the base 67a in the circumferential direction, a base-side wide width portion 71, a narrow width portion 72, and a terminal-side wide width portion 73. In this example, the width W71 of the base-side wide width portion 71 in the second direction and the width W73 of the terminal-side wide width portion 73 in the second direction are identical, and the width W72 of the narrow width portion 72 in the second direction is smaller than the width W71 of the base-side wide width portion 71 and the width W73 of the terminal-side wide width portion 73 in the second direction (W72 < W71 = W73).

[0168] In this example, each of the two arm portions 68a includes a bent portion 69 that bends radially outward from the distal end of the distal wide portion 73. The width of the bent portion 69 in the second direction is the same as the width W73 of the distal wide portion 73 in the second direction. However, the bent portion 69 may be omitted.

[0169] The elastic force of the elastic member 21a can be adjusted by adjusting the width dimension W68 in the second direction of the narrow portion 72 of the two arm portions 68a. Specifically, in the worm reducer of this example, by adjusting the width dimension W72 in the second direction of the narrow portion 72, the force elastically applied by the elastic member 21a to the distal end of the worm 18 toward the worm wheel 17 via the spacer 20 can be appropriately adjusted. As a result, the generation of backlash at the meshing portion between the gear teeth 24 and the worm teeth 25 can be suppressed, the generation of abnormal noise can be suppressed, and an unnecessary increase in friction at this meshing portion can be prevented.

[0170] In addition, according to this embodiment, the operability of the elastic member 21a can be improved. Figure 19 (a)~ Figure 20 In addition to (c), refer to Figure 21 (a)~ Figure 22 (c) is described below.

[0171] Figure 21 (a)~ Figure 22 (c) shows a comparative example relative to the second example. In this comparative example, the two arms 68z constituting the elastic member 21z each have only the base-side wide portion 71 and the narrow portion 72z, sequentially from the side closest to the base 67a in the circumferential direction, and lack the distal-side wide portion 73. The elastic member 21z of this comparative example also allows adjustment of the elastic force by adjusting the width of the narrow portion 72z in the second direction.

[0172] The width dimension of the narrow width portion 72z of the elastic member 21z of the comparative example in the second direction is smaller than the width dimension of the base side wide width portion 71 in the second direction. Therefore, if a plurality of elastic members 21z are to be stacked in the axial direction, Figure 22 (a)~ Figure 22 As shown in (c), it will tilt toward the discontinuous portion 66, so the operation is troublesome.

[0173] On the other hand, in this example, the two arms 68a constituting the elastic member 21a have a base-side wide portion 71 and a terminal-side wide portion 73 with the same width dimensions W71 and W72 in the second direction at portions adjacent to the narrow portion 72 on both sides in the circumferential direction. Figure 20 (a)~ Figure 20As shown in (c), even when multiple elastic members 21a are overlapped in the axial direction, tilting can be prevented, thereby ensuring good handling of the elastic members 21a. This facilitates, for example, so-called strip wrapping, where multiple elastic members 21a are wrapped in an axially overlapping state. Furthermore, it is easy to place them in a fixed placement device in an axially overlapping state.

[0174] In this example, the elastic member 21a has a flat base 67a, and the base 67a has a constricted portion 70 in the middle portion in the third direction. This facilitates circumferential phase alignment of the elastic member 21a with respect to the protrusion 44 of the bracket 19. However, phase alignment of the elastic member with respect to the bracket can be achieved by any other method, such as by displaying markings. In this case, the base can be configured as a partial cylinder and / or the constricted portion can be omitted.

[0175] As described above, the following contents are disclosed in this specification.

[0176] (1) A worm reducer comprising:

[0177] a housing having a worm wheel housing portion and a worm housing portion, wherein the worm housing portion is arranged in a twisted position relative to the worm wheel housing portion and an axially intermediate portion is open to the worm wheel housing portion;

[0178] a worm wheel having gear teeth on an outer peripheral surface and rotatably supported inside the worm wheel housing;

[0179] a worm having worm teeth on an outer peripheral surface thereof that mesh with the gear teeth and being rotatably supported inside the worm housing;

[0180] a bracket, the bracket comprising a protruding portion and two bracket engaging portions, the protruding portion including two guide portions, the two guide portions being separately arranged in a third direction orthogonal to both a first direction and a second direction, the first direction being a direction of distal movement of the distal end of the worm relative to the worm wheel, the second direction being an axial direction of the worm receiving portion, the two bracket engaging portions being provided on mutually opposing inner side surfaces of the two guide portions, and the bracket being arranged between the distal end of the worm and the worm receiving portion;

[0181] a gasket comprising a gasket base, two gasket engaging portions, and a gasket elastic pressing portion, wherein the gasket base is arranged between the two guide portions, the two gasket engaging portions are provided on both side surfaces of the gasket base in the third direction and are in contact with the two bracket engaging portions, and the gasket elastic pressing portion applies pre-compression to the contact portion between the bracket engaging portion and the gasket engaging portion by elastically pressing a portion of the bracket toward the second direction; and

[0182] an elastic member that is provided to bridge the protrusion and the liner base and elastically urges the distal end of the worm toward the worm wheel via the liner.

[0183] The bracket or the pad has a first grease supply portion near the contact portion between the elastic member and the pad base for supplying grease to the contact portion between the elastic member and the pad base.

[0184] The bracket includes a second grease supply portion near a contact portion between the elastic member and the protrusion for supplying grease to the contact portion between the elastic member and the protrusion.

[0185] (2) The worm reducer according to (1), wherein the bracket has a side plate portion bent radially outward from a base end portion of the protruding portion.

[0186] The first grease supply portion is provided in the second direction to penetrate a portion of the side plate portion whose circumferential phase substantially coincides with a contact portion between the elastic member and the pad base.

[0187] (3) A worm reducer according to (1) or (2), wherein the second grease supply portion is arranged in a manner that radially penetrates a portion of the protrusion whose circumferential phase is substantially consistent with that of the contact portion, wherein the contact portion is the contact portion between the elastic component and the protrusion.

[0188] (4) The worm reducer according to any one of (1) to (3), wherein the protruding portion has a connecting portion that connects end portions of the two guide portions on the side closer to the worm wheel in the first direction.

[0189] (5) The worm reducer according to any one of (1) to (4), wherein the two bracket engaging portions are composed of two bracket inclined surfaces inclined in directions approaching each other as they go toward one side in the second direction,

[0190] The two gasket engaging portions are composed of two gasket inclined surfaces that are in surface contact with the two bracket inclined surfaces.

[0191] (6) A worm reducer according to any one of (1) to (5), wherein the pad elastic pressing portion is composed of two pad elastic pressing plates, the two pad elastic pressing plates are located on one side of the second direction relative to the two pad engaging portions, and extend from the center of the pad in the third direction toward the sides separated from each other in the third direction,

[0192] The two guide parts each have a bracket pressed surface on one side of the end surface of the second direction.

[0193] The two gasket elastic pressing plates elastically press the pressed surface of the bracket toward the other side of the second direction, thereby applying preload to the contact portion between the bracket engaging portion and the gasket engaging portion.

[0194] (7) The worm reducer according to (6), wherein the two spacer elastic pressing plates each have a slit penetrating in the second direction and extending in the first direction at an end portion on the center side of the spacer in the third direction.

[0195] (8) The worm reducer according to any one of (1) to (7), wherein the elastic member is formed of a leaf spring.

[0196] (9) A method for assembling a worm reducer, which is the method for assembling a worm reducer according to any one of (1) to (8), comprising the following steps:

[0197] With the bracket, the gasket and the elastic component assembled on the inner side of the worm housing, grease is filled into the inner side of the worm housing, a portion of the grease is supplied to the contact portion between the elastic component and the gasket base through the first grease supply portion, and the grease is supplied to the contact portion between the elastic component and the protrusion through the second grease supply portion, and then the tip of the worm is embedded in the gasket and arranged radially inward of the bracket.

[0198] In addition, this application is based on the Japanese patent application (Japanese Patent Application No. 2023-016521) filed on February 7, 2023, the contents of which are incorporated herein by reference.

[0199] Description of Reference Numerals

[0200] 1 Electric power steering

[0201] 2 Steering wheel

[0202] 3 Steering axles

[0203] 4 Steering column

[0204] 5a, 5b universal joints

[0205] 6 Intermediate shaft

[0206] 7 Steering gear unit

[0207] 8 Electric assist device

[0208] 9 Pinion shaft

[0209] 10 Rack shaft

[0210] 11 Housing

[0211] 12 Rack housing

[0212] 13 Pinion housing

[0213] 14 Worm reducer

[0214] 15 Electric Motor

[0215] 16 Housing

[0216] 17 Worm gear

[0217] 18 Worm

[0218] 19 bracket

[0219] 20, 20z pad

[0220] 21, 21a, 21z elastic components

[0221] 22 Worm gear housing

[0222] 23 Worm housing

[0223] 24 teeth

[0224] 25 worm teeth

[0225] 26 Internal spline

[0226] 27 Output shaft

[0227] 28 External spline

[0228] 29 ball bearings

[0229] 30 Small diameter cylindrical face

[0230] 31 Large diameter cylindrical surface

[0231] 32 Support bearings

[0232] 33 inner circle

[0233] 34 outer ring

[0234] 35 Ball

[0235] 36 Bushing

[0236] 37 retainer

[0237] 38 fitting cylinder

[0238] 39 Inward flange

[0239] 40 Wave Washer

[0240] 41 Bracket inclined surface

[0241] 42 annular part

[0242] 43 side panel

[0243] 44 protrusion

[0244] 45 flat part

[0245] 46 inner circumference

[0246] 47 recess

[0247] 48 Steps

[0248] 49 Guidance Department

[0249] 50 connection

[0250] 51 inner side

[0251] 52, 52a bracket pressed surface

[0252] 53, 53a Pad inclined surface

[0253] 54, 54z cushion elastic pressing plate

[0254] 55 Pad base

[0255] 56 through holes

[0256] 57 Flat Plate

[0257] 58 base body

[0258] 59 base extension

[0259] 60 oblong hole

[0260] 61 circular hole

[0261] 62 pressed part

[0262] 63 Base surface 64a, 64b, 64c, 64d, 64e, 64f, 64z1, 64z2 Protrusion 65 Slit

[0263] 66 Discontinuity

[0264] Base of 67 and 67a

[0265] 68, 68a, 68z arms

[0266] 69 bending part

[0267] 70 contraction

[0268] 71 Base side wide part

[0269] 72, 72z narrow section

[0270] 73 End side wide part

[0271] 74 First grease supply unit

[0272] 75 Second grease supply unit

[0273] 76 pad elastic pressing portion

[0274] 100 Worm reducer

[0275] 101 housing

[0276] 102 Worm Gear

[0277] 103 Worm

[0278] 104 Worm gear housing

[0279] 105 worm housing

[0280] 106 gear teeth

[0281] 107 Rotation Axis

[0282] 108 worm teeth

[0283] 109a, 109b ball bearings

[0284] 110 bracket

[0285] 111 Large diameter part

[0286] 112 Bushing

[0287] 113 Electric Motor

[0288] 114 Pad

[0289] 115 Torsion coil spring

Claims

1. A worm reducer, characterized in that: have: a housing having a worm wheel housing portion and a worm housing portion, wherein the worm housing portion is arranged in a twisted position relative to the worm wheel housing portion and an axially intermediate portion is open to the worm wheel housing portion; a worm wheel having gear teeth on an outer peripheral surface and rotatably supported inside the worm wheel housing; a worm having worm teeth on an outer peripheral surface thereof that mesh with the gear teeth and being rotatably supported inside the worm housing; a bracket, the bracket comprising a protruding portion and two bracket engaging portions, the protruding portion including two guide portions, the two guide portions being separately arranged in a third direction orthogonal to both a first direction and a second direction, the first direction being a direction of distal movement of the distal end of the worm relative to the worm wheel, the second direction being an axial direction of the worm receiving portion, the two bracket engaging portions being provided on mutually opposing inner side surfaces of the two guide portions, and the bracket being arranged between the distal end of the worm and the worm receiving portion; a pad having a pad base, two pad clamping portions, and a pad elastic pressing portion, wherein the pad base is arranged between the two guide portions, the two pad clamping portions are provided on both side surfaces of the pad base in the third direction and are in contact with the two bracket clamping portions, and the pad elastic pressing portion applies pre-compression to the contact portion between the bracket clamping portion and the pad clamping portion by elastically pressing a portion of the bracket toward the second direction; as well as an elastic member that is provided to bridge the protrusion and the liner base and elastically urges the distal end of the worm toward the worm wheel via the liner. The bracket or the pad has a first grease supply portion near the contact portion between the elastic member and the pad base for supplying grease to the contact portion between the elastic member and the pad base. The bracket includes a second grease supply portion near a contact portion between the elastic member and the protrusion for supplying grease to the contact portion between the elastic member and the protrusion.

2. The worm reducer according to claim 1, characterized in that: The bracket includes a side plate portion bent radially outward from a base end portion of the protruding portion. The first grease supply portion is provided to penetrate a portion of the side plate portion in the second direction and substantially coincide with a contact portion in phase in the circumferential direction, the contact portion being a contact portion between the elastic member and the pad base.

3. The worm reducer according to claim 1, characterized in that The second grease supply portion is provided to radially penetrate a portion of the protruding portion whose phase in the circumferential direction is substantially aligned with a contact portion between the elastic member and the protruding portion.

4. The worm reducer according to claim 1, characterized in that The protruding portion has a connecting portion that connects end portions of the two guide portions on a side closer to the worm wheel in the first direction.

5. The worm reducer according to claim 1, characterized in that: The two bracket engaging portions are composed of two bracket inclined surfaces that are inclined toward each other as they move toward one side of the second direction. The two gasket engaging portions are composed of two gasket inclined surfaces that are in surface contact with the two bracket inclined surfaces.

6. The worm reducer according to claim 1, characterized in that The pad elastic pressing portion is composed of two pad elastic pressing plates, which are located on one side of the two pad engaging portions in the second direction and extend from the center of the pad in the third direction toward the sides separated from each other in the third direction. The two guide parts each have a bracket pressed surface on one side of the end surface of the second direction. The two gasket elastic pressing plates elastically press the pressed surface of the bracket toward the other side of the second direction, thereby applying preload to the contact portion between the bracket engaging portion and the gasket engaging portion.

7. The worm reducer according to claim 6, characterized in that The two gasket elastic pressing plates each have a slit extending in the second direction and extending in the first direction at an end portion on a center side of the gasket in the third direction.

8. The worm reducer according to claim 1, characterized in that The elastic member is composed of a leaf spring.

9. A method for assembling a worm reducer, characterized in that: The assembling method of a worm reducer according to any one of claims 1 to 8 comprises the following steps: With the bracket, the gasket and the elastic component assembled on the inner side of the worm housing, grease is filled into the inner side of the worm housing, a portion of the grease is supplied to the contact portion between the elastic component and the gasket base through the first grease supply portion, and the grease is supplied to the contact portion between the elastic component and the protrusion through the second grease supply portion, and then the tip of the worm is embedded in the gasket and arranged radially inward of the bracket.

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