WO2016148248A1

WO2016148248A1 - Worm reduction gear and electric power steering device

Info

Publication number: WO2016148248A1
Application number: PCT/JP2016/058546
Authority: WO
Inventors: 尚史川村; 麻衣山内
Original assignee: 株式会社ジェイテクト
Priority date: 2015-03-18
Filing date: 2016-03-17
Publication date: 2016-09-22
Also published as: JP6731164B2; JPWO2016148248A1

Abstract

A strike-plate-forming member (52; 52Q; 52S; 52T; 52V; 52W; 52X) is provided to an outer ring (4) of a second bearing (34), which supports a second end part (18b) of a worm shaft (18). The strike-plate-forming member forms a strike plate (55; 55Q; 55V; 55X) arranged on the axially outer side (X2) of the second end part (18b) and/or the second bearing (34). An urging member (70; 70Q; 90; 100; 110; 120; 70V; 70X) is adjacent in the axial direction (X) to the second end part and/or the second bearing, and is arranged between a housing (17; 17V; 17X) and the strike plate. The urging member urges the second end part relative to the housing, with the strike-plate-forming member and the second bearing interposed therebetween, so that the worm shaft (18) moves nearer to a worm wheel (19).

Description

Worm reducer and electric power steering device

The present invention relates to a worm reducer and an electric power steering device.

In order to suppress backlash between the worm shaft connected to the electric motor and the worm wheel connected to the steering shaft in the worm speed reducer of the electric power steering device that transmits the rotation output of the electric motor to the steering shaft. Various structures for urging the end of the worm shaft toward the worm wheel by the urging member have been proposed (see, for example, Patent Documents 1 and 2).

In Patent Document 1, a compression coil spring disposed radially outward from the end of the worm shaft biases the end of the worm shaft toward the worm wheel via a bearing that supports the end of the worm shaft. ing.

In Patent Document 2, the worm shaft includes an extending portion that passes through the bearing and protrudes axially outward from the bearing, and the compression coil spring is a fluororesin-coated bush that fits into the extending portion. The extending portion is urged toward the worm wheel via the.

International Publication No. WO2011 / 104217 Pamphlet JP 2010-116150 A

In the worm speed reducer of Patent Document 1, the urging member is disposed radially outward of the bearing. For this reason, the worm speed reducer is enlarged in the radial direction of the worm shaft, which is not preferable from the viewpoint of mounting on a vehicle or the like.

On the other hand, in the worm speed reducer of Patent Document 2, the urging member is disposed radially outward of the extended portion of the worm shaft. Therefore, compared with the worm reduction gear of patent document 1, the mounting property to a vehicle etc. becomes favorable. However, since the urging member urges the worm shaft without using a bearing, loss torque is generated and assist torque is reduced. In the worm speed reducer disclosed in Patent Document 2, a bush is disposed on the outer periphery of the extending portion in order to reduce the loss torque. However, the loss torque is increased as compared with the worm speed reducer disclosed in Patent Document 1.

Therefore, an object of the present invention is to improve mountability to a vehicle or the like while suppressing loss torque in a worm speed reducer.

The invention of claim 1 includes a housing (17), a first end (18a) housed in the housing and connected to the electric motor (14), and a second end located opposite to the first end. A worm shaft (18) having an end (18b), a worm wheel meshing with the worm shaft (19), a first bearing (33) for rotatably supporting the first end with respect to the housing; A second bearing (34) that rotatably supports the second end portion, and a receiving seat (55; 55Q) disposed on an axially outer side (X2) of at least one of the second end portion and the second bearing. 55V; 55X), a receiving seat forming member (52; 52Q; 52S; 52T; 52V; 52W; 52X) provided on the outer ring (43) of the second bearing, the second end and the Less of the second bearing Both of which are adjacent to each other in the axial direction (X) and disposed between the housing and the receiving seat, and the receiving seat forming member with respect to the housing so that the worm shaft approaches the worm wheel, and A worm speed reducer comprising: a biasing member (70; 70Q; 90; 100; 110; 120; 70V; 70X) for biasing the second end portion via the second bearing. 15; 15P; 15Q; 15S; 15T; 15U; 15V; 15W; 15X).

In addition, although the alphanumeric characters in parentheses represent corresponding components in the embodiments described later, this does not mean that the present invention should be limited to those embodiments. The same applies hereinafter.

As in claim 2, the biasing member may include a compression spring (70; 90; 100; 110; 70V; 70X) that presses and biases the receiving seat toward the worm wheel.

As in claim 3, the receiving seat may be disposed closer to the worm wheel than the central axis (C1) of the worm shaft.

According to a fourth aspect of the present invention, a bearing holder (50; 50Q; 50V; 50W; 50X) for holding the second bearing may be provided, and the receiving seat forming member may be provided integrally with the bearing holder.

As in claim 5, the housing or the member (80; 44X) held by the housing moves the biasing member in a biasing direction (Y2) and in a direction opposite to the biasing direction (Y1). The guide part (64; 84; 64V; 44Xb) which guides the movement of a bearing holder may be included.

The housing includes a holding hole (61X) that holds the bearing holder and is open at one end, and the lid member (44X) fitted to the bearing holder and the one end of the holding hole. ) And a compression spring (70X) as the urging means interposed between the bearing holder and the lid member.

As in claim 7, the bearing member engages with the guided portion (52Xa) of the bearing holder, and the bearing holder moves in the biasing direction of the biasing member and in the direction opposite to the biasing direction. A guide unit (44Xb) for guiding the movement of the camera may be included.

As in claim 8, the guide part may be key-coupled to the guided part.

According to a ninth aspect of the present invention, the cover member engages with the bearing holder in the state of the subassembly, and has an engaging projection (44Xc) that receives the biasing load of the compression spring via the bearing holder. May be included.

As in claim 10, the subassembly may include a buffer member (240) interposed between the bearing holder and the housing.

As in the eleventh aspect, the bearing holder may include a C-shaped fitting portion (51We; 51X) which is fitted to the outer periphery of the outer ring of the second bearing and opened to the worm wheel side.

As in claim 12, the bearing holder (50W) includes a C-shaped fitting portion (51We) fitted to the outer periphery (43a) of the outer ring of the second bearing, and extends from the fitting portion. Including a pair of flanges (51Wg, 51Wh) that respectively contact the pair of end surfaces (43b) of the outer ring of the second bearing, and may be made of resin.

As in claim 13, at least one of the second end portion and the second bearing is axially outward and is disposed between the receiving seat forming member (52V) and the housing (17V). A member (140) may be provided.

As in the fourteenth aspect, the buffer member may include a rubber member, and the bearing holder may be in contact with the housing when the rubber member is compressed by a predetermined amount.

A bearing holder (50V; 50W) that fits on an outer periphery of the outer ring of the second bearing and holds the second bearing as in claim 15, wherein the housing is axially outer with respect to the bearing holder. A step portion (153) adjacent to the side may be included.

As in claim 16, the receiving seat forming member (52V; 52W) is a first restraining portion for restraining movement of one end of the biasing member in a direction intersecting with the biasing direction of the biasing member. 60), and the buffer member may include a second restraining portion (141) for restraining movement of the other end of the biasing member in a direction crossing the biasing direction of the biasing member. Good.

As in claim 17, the receiving seat may be disposed adjacent to an end surface (18d) of the second end portion of the worm shaft.

A second receiving seat (133; 133T) for receiving the biasing member on the opposite side of the first receiving seat as the receiving seat as in claim 18 and restricting the set length (L) of the biasing member Spacers (130; 130T; 130U) may be provided.

As in the nineteenth aspect, a support portion (17b; 44b; 88) provided on the housing or a member (44T; 80U) held by the housing and supporting the spacer may be provided.

The invention of claim 20 provides an electric power steering device (1; 1P; 1Q) for transmitting the power of an electric motor to a steering shaft via the worm reducer.

According to the invention of claim 1, the urging member is adjacent to at least one of the second end portion of the worm shaft and the second bearing, and is formed between the housing and the receiving seat of the receiving seat forming member. Since it is disposed between them, it is possible to improve mountability to a vehicle or the like while suppressing loss torque.

According to invention of Claim 2, size reduction is achieved by the layout which arrange | positions the compression spring as an urging member adjacent to the axial direction of the 2nd end part of a worm shaft, and the 2nd bearing at least. it can.

According to the invention of claim 3, it is possible to secure a wide space for arranging the compression springs in the urging direction of the compression springs.

According to the invention of claim 4, since the receiving seat forming member is provided integrally with the bearing holder, the structure can be simplified.

According to the invention of claim 5, the second end portion of the worm shaft can be smoothly guided by the guide portion in the urging direction of the urging member and in the direction opposite to the urging direction.

According to the invention of claim 6, since the bearing holder, the lid member, and the compression spring can be collectively assembled into the holding hole of the housing as a subassembly, the assemblability is improved.

According to the seventh aspect of the invention, the second end portion of the worm shaft can be smoothly guided in the biasing direction of the biasing member and in the direction opposite to the biasing direction by the guide portion of the lid member.

According to the eighth aspect of the present invention, the function of guiding the second end portion of the worm shaft is achieved while the lid member and the bearing holder are unitized by key coupling between the guide portion of the lid member and the guided portion of the bearing holder. can do.

According to the invention of claim 9, the biasing load of the compression spring is exerted on the lid member and the bearing holder, and unitization of the lid member, the bearing holder and the compression spring can be achieved.

According to the invention of claim 10, since the subassembly includes the buffer member, the assemblability is further improved.

According to the invention of claim 11, the bearing holder includes a C-shaped fitting portion that opens to the worm wheel side. For this reason, even if the worm shaft is reduced in size in the axial direction so that the second end of the worm shaft approaches the first end, the bearing holder does not interfere with the worm wheel. As much as possible, the worm speed reducer can be reduced in size with respect to the axial direction of the worm shaft.

According to the invention of claim 12, it is not necessary to press-fit the second bearing into the C-shaped fitting portion of the bearing holder. Therefore, it is possible to suppress the occurrence of creep of the fitting portion and to prevent the bearing holder from falling off the second bearing. The bearing holder holds the second bearing by the C-shaped fitting portion and the pair of flanges. For this reason, even if a temperature change or a dimensional change due to water absorption occurs in the bearing holder, it is possible to prevent the bearing holder from falling off the second bearing.

According to the invention of claim 13, the following effects are obtained. That is, if the buffer member is disposed radially outward of the second bearing, the inner diameter of the accommodation hole that accommodates the worm shaft in the housing is increased. For this reason, there exists a possibility that a 1st bearing may enlarge, or a housing may enlarge. In contrast, this is not the case with the present invention.

According to the fourteenth aspect of the present invention, excessive compression of the rubber member can be suppressed to prevent the rubber member from sagging.

According to the fifteenth aspect of the present invention, it is possible to prevent the bearing holder from falling off the second bearing by the stepped portion of the housing.

According to the sixteenth aspect of the present invention, the buckling and displacement of the biasing member can be suppressed by the first restraining portion and the second restraining portion.

According to the invention of claim 17, the following effects are obtained. That is, the dimensional change due to the temperature change of the receiving seat forming member provided on the outer ring tends to increase as the position is radially outward. On the other hand, in the present invention, the receiving seat forming member is arranged in the axially outer side of the second end portion of the worm shaft so as to be arranged at the radial center or near the center. For this reason, even if the dimension of a receiving seat formation member changes with temperature changes, the change of the position of a receiving seat is small. Therefore, the set length of the urging member hardly changes and the urging load is stabilized.

According to the invention of claim 18, the set length of the biasing member can be easily adjusted by changing the specification of the spacer.

According to the nineteenth aspect of the invention, the spacer can be supported by the support portion provided in the housing or the like.

According to the invention of claim 20, a small electric power steering device can be realized.

It is a mimetic diagram showing a schematic structure of an electric power steering device to which a worm reduction gear of a 1st embodiment of the present invention is applied. It is sectional drawing of the principal part of the worm reduction gear of 1st Embodiment of this invention. FIG. 3A is a sectional view taken along line III-III in FIG. FIG. 3B is a partially enlarged view of the bearing holder and the bearing in FIG. 2. It is a disassembled perspective view of the principal part of the worm reduction gear of 1st Embodiment of this invention. It is sectional drawing of the principal part of the worm reduction gear of 2nd Embodiment of this invention. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5. It is a disassembled perspective view of the principal part of the worm gear reducer of 2nd Embodiment of this invention. It is sectional drawing of the principal part of the worm reduction gear of 3rd Embodiment of this invention. In 3rd Embodiment, it is a schematic sectional drawing of the structure which receives a tension spring. It is sectional drawing of the principal part of the worm reduction gear of 4th Embodiment of this invention. It is a schematic diagram of the urging | biasing part of 5th Embodiment of this invention. It is a schematic diagram of the urging | biasing part of 6th Embodiment of this invention. It is a schematic diagram of the urging | biasing part of 7th Embodiment of this invention. It is a schematic diagram of the urging | biasing part of 8th Embodiment of this invention. It is sectional drawing of the principal part of the worm gear reducer of 9th Embodiment of this invention. It is sectional drawing of the principal part of the worm speed reducer of 10th Embodiment of this invention. In 10th Embodiment, it is the schematic of the structure which guides a compression coil spring. It is sectional drawing of the principal part of the worm reduction gear of 11th Embodiment of this invention. It is sectional drawing of the principal part of the worm gear reducer of 12th Embodiment of this invention. FIG. 20 is a sectional view taken along line XX-XX in FIG. It is a disassembled perspective view of the principal part of the worm speed reducer of 12th Embodiment. In 12th Embodiment, it is a schematic sectional drawing of a compression coil spring and a spring end support part. It is sectional drawing of the principal part of the worm reduction gear of 13th Embodiment of this invention. It is a disassembled perspective view of the principal part of the worm speed reducer of 13th Embodiment. It is sectional drawing of the principal part of the worm reduction gear of 14th Embodiment of this invention. In 14th Embodiment, it is a partial cross section figure of the principal part of a worm reduction gear. In 14th Embodiment, it is a perspective view of the subassembly of a worm reduction gear. In 14th Embodiment, it is sectional drawing of the said subassembly. In 14th Embodiment, it is a disassembled perspective view of the bearing holder and buffer member of the said subassembly. In 14th Embodiment, it is a disassembled perspective view of the said subassembly. In 14th Embodiment, it is a disassembled perspective view from another angle of the said subassembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.
(First embodiment)
The outline of the electric power steering apparatus including the worm reduction gear according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing a schematic configuration of an electric power steering apparatus including a worm reduction gear according to a first embodiment of the present invention.

The electric power steering device 1 includes a steering mechanism 4 and a snake mechanism A, and steers the steered wheels 3 based on the driver's operation of the steering wheel 2 (steering member). The steering mechanism 4 includes an assist mechanism 5 that assists the driver's steering operation.

The steering mechanism 4 includes a steering shaft 6 that rotates in conjunction with the rotation of the steering wheel 2. The steering shaft 6 includes an input shaft 7a, an output shaft 7b, an intermediate shaft 9, and a pinion shaft 11. The input shaft 7a is connected to the steering wheel 2 (steering member).

The output shaft 7b is connected to the input shaft 7a via a torsion bar 7c. Further, the output shaft 7 b is connected to the intermediate shaft 9 through the universal joint 8. The intermediate shaft 9 is connected to a pinion shaft 11 having a pinion 11 a through a universal joint 10.

The snake mechanism A has a rack shaft 12 and a tie rod 13. The rack shaft 12 has a rack 12a meshed with the pinion 11a. One end of the tie rod 13 is connected to the rack shaft 12, and the other end is connected to the snake ring 3.

When the steering wheel 2 rotates according to the driver's operation of the steering wheel 2, the pinion shaft 11 rotates through the input shaft 7a, the output shaft 7b, and the intermediate shaft 9. The rotation of the pinion shaft 11 is converted into a reciprocating motion in the axial direction of the rack shaft 12 by the steering mechanism A. The turning angle of the steered wheels 3 is changed by the reciprocating motion of the rack shaft 12 in the axial direction.

The assist mechanism 5 includes a torque sensor 21, an ECU (Electronic Control Unit) 16, an electric motor 14, and a worm speed reducer 15.

The torque sensor 21 detects the amount of twist between the input shaft 7a and the output shaft 7b. The ECU 16 determines the assist torque based on the steering torque T obtained from the torsion amount detected by the torque sensor 21 and the vehicle speed V detected by a vehicle speed sensor (not shown). The electric motor 14 is driven and controlled by the ECU 16. The worm speed reducer 15 transmits the rotational force of the electric motor 14 to the output shaft 7b. As a result, assist torque is applied to the output shaft 7b to assist the driver's steering operation.

The worm reduction gear according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view of a main part of the worm reduction gear according to the first embodiment of the present invention.

As shown in FIG. 2, the worm speed reducer 15 includes a housing 17, a worm shaft 18, a first bearing 33, a second bearing 34, a worm wheel 19, and an urging portion. The worm shaft 18, the first bearing 33, the second bearing 34, the worm wheel 19 and the urging portion are accommodated in the housing 17.

The worm shaft 18 has a first end portion 18a and a second end portion 18b that are separated in the axial direction X, and a tooth portion 18c at an intermediate portion between the first end portion 18a and the second end portion 18b. The worm shaft 18 is accommodated in the accommodating portion 17 a of the housing 17. The worm shaft 18 is disposed coaxially with the output shaft 14 a of the electric motor 14. The first end 18 a of the worm shaft 18 faces the end of the output shaft 14 a of the electric motor 14 in the axial direction X. The first end portion 18a of the worm shaft 18 and the end portion of the output shaft 14a of the electric motor 14 are connected via a power transmission joint 20 so that torque can be transmitted.

The power transmission joint 20 includes a first rotating element 23, a second rotating element 24, and an intermediate element 25. The first rotating element 23 is fixed to the first end 18a of the worm shaft 18 so as to be integrally rotatable. The second rotating element 24 is fixed to the end of the output shaft 14a of the electric motor 14 so as to be integrally rotatable.

The first rotating element 23 has a plurality of engaging protrusions 29 protruding in the axial direction X toward the second rotating element 24. The plurality of engaging protrusions 29 are arranged in the rotational direction Z (corresponding to the circumferential direction) with an interval in the rotational direction Z. The second rotating element 24 has a plurality of engaging protrusions 30 that protrude in the axial direction X toward the first rotating element 23. The plurality of engaging protrusions 30 are arranged in the rotational direction Z (corresponding to the circumferential direction) with an interval in the rotational direction Z. The engagement protrusions 29 of the first rotation element 23 and the engagement protrusions 30 of the second rotation element 24 are alternately arranged with an interval in the rotation direction Z.

The intermediate element 25 includes a plurality of engaging protrusions 32 extending radially outward in the radial direction. Each of the plurality of engaging protrusions 32 is disposed between the engaging protrusion 29 of the first rotating element 23 and the engaging protrusion 30 of the second rotating element 24 in the rotation direction Z. Therefore, the torque of the output shaft 14 a of the electric motor 14 is transmitted to the worm shaft 18 through the second rotating element 24, the intermediate element 25 and the first rotating element 23. In addition, the intermediate element 25 is configured by an elastic member. Therefore, the first rotating element 23 is configured to be swingable with respect to the second rotating element 24. That is, the worm shaft 18 is slidably connected to the output shaft 14a of the electric motor 14.

The worm wheel 19 has a metal core part 19a and a tooth part 19b. The cored bar portion 19a is made of, for example, a metal material and is formed in an annular shape.

The metal core 19a is fitted to the outer periphery of the output shaft 7b and rotates integrally with the output shaft 7b. The tooth portion 19b is made of, for example, a resin material and is formed in an annular shape. The present invention is not limited to the column assist type of the present embodiment in which the torque of the electric motor 14 is applied to the output shaft 7b upstream of the pinion shaft 11. For example, a pinion assist type that applies the torque of the electric motor 14 to the pinion shaft 11 may be used. In this case, the worm wheel 19 is fixed to the pinion shaft 11.

The tooth part 19b is fitted to the outer periphery of the cored bar part 19a and rotates integrally with the cored bar part 19a. Teeth 19c that mesh with the teeth of the tooth portion 18c of the worm shaft 18 are formed on the outer peripheral surface of the tooth portion 19b.

The first bearing 33 is constituted by, for example, a rolling bearing. The first bearing 33 has an inner ring 35, an outer ring 37, and a plurality of rolling elements. The inner ring 35 is fitted to the outer periphery of the first end 18 a of the worm shaft 18 and rotates integrally with the worm shaft 18. The outer ring 37 is fitted in a bearing hole 36 provided in the housing 17. The outer ring 37 is clamped in the axial direction between a positioning step 38 at the end of the bearing hole 36 and a fixing member 39 screwed into the bearing hole 36. The first bearing 33 has an internal gap.

In the present embodiment, the intermediate element 25 of the power transmission joint 20 is constituted by an elastic member, and a slight gap is set between the plurality of rolling elements and the inner ring 35 and the outer ring 37. Therefore, the worm shaft 18 is supported so as to be swingable with respect to the housing 17 with the center B of the first bearing 33 as a fulcrum.

The second bearing 34 is constituted by a rolling bearing, for example. The second bearing 34 has an inner ring 40, an outer ring 43, and a plurality of rolling elements. The second bearing 34 is accommodated in the holding hole 61 of the housing 17. The inner ring 40 is fitted to the second end 18 b of the worm shaft 18 and rotates integrally with the worm shaft 18. One end surface of the inner ring 40 is in contact with a positioning step portion 42 formed at the second end portion 18 b of the worm shaft 18.

Details of the urging unit of the worm reduction gear according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 3A is a cross-sectional view taken along the line III-III in FIG. FIG. 3B is a partially enlarged view of the bearing holder and the bearing of FIG. FIG. 4 is an exploded perspective view of a main part of the worm speed reducer according to the first embodiment of the present invention.

The urging portion of this embodiment has a bearing holder 50 provided with a spring seat forming portion 52 as a receiving seat forming member, and a compression coil spring 70 that provides a compression spring as an urging member. The biasing member (compression coil spring 70) has the spring seat forming portion 52 and the second bearing 34 with respect to the housing 17 with the center B of the first bearing 33 as a fulcrum so that the worm shaft 18 approaches the worm wheel 19. The second end portion 18b of the worm shaft 18 is biased toward the worm wheel 19 via the worm wheel 18.

The housing 17 has a holding hole 61 for holding the second bearing 34 via the bearing holder 50. The bearing holder 50 and the compression coil spring 70 are accommodated in the holding hole 61 together with the second end portion 18 b of the worm shaft 18 and the second bearing 34.

The holding hole 61 is formed in a biased hole so as to hold the bearing holder 50 so that the second end portion 18b of the worm shaft 18 can move in the first direction Y1 and the second direction Y2. The first direction Y1 is a direction in which the center distance D1 between the worm shaft 18 and the worm wheel 19 increases. The second direction Y2 is a direction in which the center distance D1 between the worm shaft 18 and the worm wheel 19 decreases. The second direction Y 2 corresponds to the biasing direction of the compression coil spring 70 with respect to the spring seat forming portion 52. The first direction Y1 corresponds to a direction opposite to the biasing direction of the compression coil spring 70.

A second spring seat 65 as a second receiving seat is formed on the inner surface 62 which is, for example, the inner periphery of the holding hole 61 away from the worm wheel 19. Specifically, as shown in FIG. 3A, a recess 62 a as a spring end support portion is formed on the inner surface 62. The recessed part 62a has the 2nd spring seat 65 and the 2nd spring guide 69 as a 2nd restraint part.

That is, a second spring seat 65 that receives the second end 72 of the compression coil spring 70 is formed by the bottom of the recess 62a. In addition, a second spring guide 69 as a second restraining portion is formed by the inner wall surface of the recess 62a. The second spring guide 69 (second restraint portion) restrains the movement of the second end portion 72 of the compression coil spring 70 in the direction intersecting with the biasing direction (second direction Y2).

The end of the holding hole 61 in the axial direction X2 is closed by the lid member 44.

The bearing holder 50 has a main body 51 and a spring seat forming portion 52 as a receiving seat forming member. In the present embodiment, the main body 51 and the spring seat forming part 52 are integrally formed of a resin material such as polyamide, for example.

The main body 51 is formed in an annular shape that defines the fitting hole 53. The main body 51 is fitted on the outer periphery 43 a of the outer ring 43 of the second bearing 34. The spring seat forming portion 52 is formed in a substantially D shape when viewed from the axial direction X. The spring seat forming portion 52 protrudes axially outward X2 (leftward in FIG. 2) from the axially outward end surface 51a of the main body 51.

The spring seat forming portion 52 is disposed at a position near the worm wheel 19 of the main body portion 51, that is, at a position away from the second spring seat 65 of the holding hole 61. As shown in FIG. 3A, a flat surface 52a is formed on the spring seat forming portion 52 so as to face the second spring seat 65 of the holding hole 61. The flat surface 52a includes a flat surface 52a shown in FIG. ), A recess 56 is formed as a spring end support. The spring seat forming portion 52 includes a first spring seat 55 as a first receiving seat and a first spring guide 57 as a first restraining portion in the recess 56.

That is, the first spring seat 55 that receives the first end 71 of the compression coil spring 70 is formed by the bottom of the recess 56. A first spring guide 57 is formed by the inner wall surface of the recess 56. The first spring guide 57 constrains the movement of the first end 71 of the compression coil spring 70 in a direction intersecting the urging direction (second direction Y2). A compression coil spring 70 as a compression spring presses and urges the first spring seat 55 toward the worm wheel 19 side.

In the present embodiment, as shown in FIG. 3B, the spring seat forming portion 52 (receiving seat forming member) including the first spring seat 55 (first receiving seat) is provided between the main body portion 51 and the second bearing 34. A part of the outer ring 43 is located on the axially outer side X2. The spring seat forming portion 52 is formed with a positioning portion 52b. The positioning part 52 b positions the outer ring 43 in the axial direction X by contacting the end surface 43 b of the outer ring 43 of the second bearing 34. Further, the spring seat forming portion 52 is disposed closer to the worm wheel 19 than the central axis C 1 of the worm shaft 18 when viewed in the axial direction X.

In this embodiment, the biasing member is a compression coil spring 70 made of, for example, a metal material. The compression coil spring 70 is disposed between the housing 17 and the spring seat forming portion 52. The first end portion 71 of the compression coil spring 70 is installed on the first spring seat 55 of the spring seat forming portion 52, and the second end portion 72 of the compression coil spring 70 is connected to the second spring seat 65 of the holding hole 61. is set up. Both ends 71 and 72 of the compression coil spring 70 are engaged with spring guides 57 and 69 formed by the inner wall surfaces of the

recesses

56 and 62a, respectively. Therefore, the compression coil spring 70 is unlikely to fall down.

The compression coil spring 70 extends from the first spring seat 55 of the spring seat forming portion 52 toward the second spring seat 65 of the holding hole 61 in the first direction Y1. In the present embodiment, the compression coil spring 70 is adjacent to the second end 18 b of the worm shaft 18 and the second bearing 34 in the axial direction.

With the above configuration, the compression coil spring 70 moves the second end portion 18b of the worm shaft 18 with respect to the housing 17 via the spring seat forming portion 52 and the second bearing 34 in the second direction Y2 (worm shaft 18 and worm wheel). 19 in a direction in which the distance D1 between the cores is reduced.

It should be noted that a guide portion 64 made of a pair of flat surfaces extending in parallel with the first direction Y1 and the second direction Y2 is formed on the inner surface 62 of the holding hole 61. On the other hand, on the outer periphery of the main body 51 of the bearing holder 50, a guided portion 54 formed of a pair of flat surfaces extending in parallel with the first direction Y1 and the second direction Y2 is formed. The guide part 64 restricts the rotation of the bearing holder 50 and the movement in the direction orthogonal to the first direction Y1 and the second direction Y2 while allowing the movement of the bearing holder 50 in the first direction Y1 and the second direction Y2. is doing.

As shown in FIG. 3A, a gap S 1 is formed between a portion close to the worm wheel 19 on the outer surface of the bearing holder 50 (the outer periphery 51 b of the main body 51) and the inner surface 62 of the holding hole 61. . For example, even when the tooth portion 19b of the worm wheel 19 is worn due to the clearance S1, the worm shaft 18 is always urged toward the worm wheel 19.

Further, a gap S2 is formed between a portion of the outer surface of the bearing holder 50 (the outer periphery 51b of the main body 51) that is away from the worm wheel 19 and the facing portion 63 of the inner surface 62 of the holding hole 61 that faces the portion. ing. When the worm shaft 18 is flipped up from the worm wheel 19 due to vibration or the like when traveling on a rough road, the inner surface 62 of the holding hole 61 restricts excessive movement of the bearing holder 50 in the first direction Y1. Thereby, deterioration of the compression coil spring 70 and damage to the worm wheel 19 are suppressed.

In the present embodiment, the biasing member (compression coil spring 70) is disposed on the second end 18b of the worm shaft 18 and the axially outward X2 of the second bearing 34. For this reason, the worm reduction gear 15 is difficult to increase in size radially outward of the worm shaft 18 and is highly mountable on a vehicle or the like.

Furthermore, the axially outward X2 of the second end 18b of the worm shaft 18 and the second bearing 34 is more biased than the radially outward of the second end 18b of the worm shaft 18 (compression coil spring 70). ) Easy to secure space to place. Therefore, the degree of freedom in selecting the type of the biasing member (compression coil spring 70), the spring length, the spring constant, and the like is great.

In the present embodiment, the biasing member (compression coil spring 70) biases the second end 18b of the worm shaft 18 via the spring seat forming portion 52 (bearing holder 50) and the second bearing 34. The second end 18b of the worm shaft 18 is not directly urged. Therefore, loss torque is suppressed.

Further, in the present embodiment, the spring seat forming portion 52 is disposed at a position offset from the second bearing 34 in the axially outward direction X2. Therefore, the urging member (compression coil spring 70) applies an urging force from a position offset outward in the axial direction with respect to the second bearing 34. As a result, the internal clearance of the second bearing 34 is closed, and abnormal noise generated by the second bearing 34 is suppressed.

Further, in the present embodiment, the spring seat forming portion 52 is disposed closer to the worm wheel 19 than the central axis C1 of the worm shaft 18. Therefore, in comparison with a conventional worm speed reducer (for example, the worm speed reducer in FIG. 8 of Patent Document 2) in which the compression coil spring is disposed radially outward of the end portion of the worm shaft, the biasing direction of the compression coil spring 70 A long (layout) layout space can be secured. For this reason, the freedom degree of the setting of a spring length is high. A long spring length can also be secured, the spring constant can be made as low as possible, and the rotational torque of the worm shaft 18 can be stabilized. Further, the spring seat forming portion 52 and the compression coil spring 70 of the bearing holder 50 can be arranged compactly with respect to the radial direction of the worm shaft 18. Furthermore, it is possible to set a large amount of bending when the compression coil spring 70 is initially set. Thereby, even when wear of the tooth surface of the worm wheel 19 proceeds with long-term use, backlash between the worm shaft 18 and the worm wheel 19 can be suppressed.

Further, as described above, the inner surface 62 of the holding hole 61 is excessively moved in the first direction Y1 of the bearing holder 50 when the worm shaft 18 is flipped up from the worm wheel 19 due to vibration or the like when traveling on a rough road. To regulate. In the present embodiment, the bearing holder 50 is made of a resin material. Therefore, abnormal noise at the time of contact between the inner surface 62 of the holding hole 61 and the bearing holder 50 is suppressed.

As described above, the guide hole 64 is formed in the holding hole 61, the guided part 54 is formed in the bearing holder 50, and the guide part 64 is connected to the first direction Y 1 and the second direction of the bearing holder 50. While allowing the movement in the direction Y2, the rotation of the bearing holder 50 and the movement in the direction orthogonal to the first direction Y1 and the second direction Y2 are restricted. In the present embodiment, the bearing holder 50 is made of a resin material. Therefore, the abnormal noise at the time of contact with the guide part 64 and the guided part 54 and the abnormal noise at the time of sliding are suppressed. Furthermore, the sliding resistance between the guide part 64 and the guided part 54 is reduced.
(Second Embodiment)
FIG. 5 is a cross-sectional view of a main part of an electric power steering apparatus 1P including a worm reduction gear 15P according to a second embodiment of the present invention. FIG. 6 is a cross-sectional view of a main part of the worm reduction gear 15P, taken along the line VI-VI in FIG. FIG. 7 is an exploded perspective view of a main part of the worm speed reducer 15P.

The worm reducer 15P of the second embodiment of FIGS. 5 to 7 is mainly different from the worm reducer 15 of the first embodiment of FIGS. 2 to 4 in the following. That is, as shown in FIGS. 5 and 6, the annular interposition member 80 is fitted and fixed to the holding hole 61 P formed of a circular hole in the housing 17. The bearing holder 50 is indirectly supported by the housing 17 via the interposed member 80. The interposition member 80 is formed of a resin such as polyamide.

As shown in FIGS. 5 to 7, the interposition member 80 includes an annular main body 81 that surrounds the outer periphery of the main body 51 of the bearing holder 50, and a spring seat that protrudes from the end surface 81a of the main body 81 in the axially outward direction X2. Forming portion 82.

The main body 81 of the interposed member 80 forms a holding hole 83 that surrounds the main body 51 of the bearing holder 50. The holding hole 83 is formed as a biasing hole that can hold the bearing holder 50 in a first direction Y1 in which the center distance D1 between the worm shaft 18 and the worm wheel 19 increases and in a second direction Y2 in which the bearing holder 50 decreases. ing.

The bearing holder 50 is guided in the first direction Y1 and the second direction Y2 by the interposed member 80 which is a member held by the housing 17.

Between the first spring seat 55 of the spring seat forming portion 52 of the bearing holder 50 and the second spring seat 85 of the spring seat forming portion 82 of the interposition member 80, the second end portion 18 b of the worm shaft 18 is axially X. A compression coil spring 70 is provided to provide a compression spring as an urging member disposed adjacently. The compression coil spring 70 elastically urges the second end portion 18b of the worm shaft 18 through the bearing holder 50 in a second direction Y2 (corresponding to the urging direction) that decreases the inter-center distance D1. *

On the inner surface 86 of the holding hole 83 of the main body 81 of the interposed member 80, a recess 86a is formed as a spring end support. The recess 86a has a second spring seat 85 as a second receiving seat and a second spring guide 89 as a second restraining portion.

That is, the second spring seat 85 that receives the second end 72 of the compression coil spring 70 is formed by the bottom of the recess 86a. In addition, a second spring guide 89 as a second restraining portion is formed by the inner wall surface of the recess 86a. The second spring guide 89 (second restraining portion) restrains the movement of the second end portion 72 of the compression coil spring 70 in a direction intersecting the urging direction (second direction Y2).

The

end portions

71, 72 of the compression coil spring 70 are engaged with spring guides 57, 89 formed in the

recesses

56, 86a, so that the compression coil spring 70 is prevented from falling.

As shown in FIGS. 6 and 7, a guide portion 84 formed of a pair of flat surfaces extending in parallel with the first direction Y 1 and the second direction Y 2 is provided on the inner periphery of the holding hole 83 of the interposed member 80. . The pair of guide portions 84 of the interposed member 80 guide the pair of guided portions 54 of the bearing holder 50. The guide portion 84 restricts the rotation of the bearing holder 50 and the movement in the direction orthogonal to the first direction Y1 and the second direction Y2 while allowing the movement of the bearing holder 50 in the first direction Y1 and the second direction Y2. is doing.

A lubricant such as grease may be interposed between each guide portion 84 and the corresponding guided portion 54. Thereby, the bearing holder 50 can be displaced more smoothly.

A gap S 1 is formed between a portion near the worm wheel 19 on the outer surface of the bearing holder 50 (the outer periphery 51 b of the main body 51) and the inner surface 86 of the holding hole 83. For example, even when the tooth portion 19 b of the worm wheel 19 is worn by the gap S 1, the worm shaft 18 is always urged toward the worm wheel 19.

Further, a gap S2 is formed between a portion of the outer surface of the bearing holder 50 (the outer periphery 51b of the main body 51) away from the worm wheel 19 and the facing portion 87 of the inner surface 86 of the holding hole 83 facing the portion. ing. When the worm shaft 18 is flipped up from the worm wheel 19 due to vibration or the like when traveling on a rough road, the inner surface 86 of the holding hole 83 restricts excessive movement of the bearing holder 50 in the first direction Y1. Thereby, deterioration of the compression coil spring 70 and damage to the worm wheel 19 are suppressed.

In the components of the second embodiment of FIGS. 5 to 7, the same components as those of the first embodiment of FIGS. 2 to 4 are referred to by the components of the first embodiment of FIGS. The same reference numerals as those in FIG.

Also in the second embodiment, the same effects as the first embodiment can be achieved. In addition, since the holding hole 83 for holding the bearing holder 50, the guide portion 84, and the second spring seat 85 are provided in the interposed member 80, which is a small component, instead of the housing 17, which is a large component, manufacturing is facilitated and manufactured. There is an advantage that it is easy to do.

The interposition member 80 is made of a resin material. Therefore, the abnormal noise at the time of contact between the inner surface 86 of the holding hole 83 and the bearing holder 50 is further suppressed.
(Third embodiment)
FIG. 8 is a cross-sectional view of a main part of an electric power steering apparatus 1Q to which a worm reduction gear 15Q according to a third embodiment of the present invention is applied.

The worm reducer 15Q of the third embodiment in FIG. 8 is mainly different from the worm reducer 15 of the first embodiment in FIG.

That is, for example, the angle-shaped spring seat forming portion 52Q (receiving seat forming member) of the bearing holder 50Q is disposed on the first direction Y1 side with respect to the central axis C1 of the worm shaft 18. Further, as the urging member, for example, a metal tension coil spring 70Q which is a tension spring is used. The tension coil spring 70Q pulls and urges the spring seat forming portion 52Q to the worm wheel 19 side (second direction Y2 side).

The first end portion 71Q and the second end portion 72Q as spring engaging portions of the tension coil spring 70Q are formed in a hook shape. The second end portion 72Q is hooked and engaged with a spring seat forming portion 66 formed of, for example, an inverted L-shaped convex portion provided on the inner periphery of the holding hole 61Q of the housing 17. The first end portion 71Q is hooked and engaged with the spring seat forming portion 52Q of the bearing holder 50Q. *

As shown in FIG. 9, the second end 72 Q is received by a second spring seat 65 Q (second receiving seat) provided in the spring seat forming portion 66. The first end portion 71Q is received by a first spring seat 55Q (first receiving seat) provided in the spring seat forming portion 52Q.

In the constituent elements of the third embodiment in FIG. 8, the same reference numerals as those in the first embodiment in FIG. 2 are assigned to the same constituent elements as those in the first embodiment in FIG. is there.

Also in 3rd Embodiment, there can exist the same effect as 1st Embodiment. Further, the spring seat forming portion 52Q and the tension coil spring 70Q can be arranged compactly with respect to the radial direction of the worm shaft 18.
(Fourth embodiment)
FIG. 10 is a cross-sectional view of a main part of a worm reduction gear 15R according to the fourth embodiment of the present invention. The worm reducer 15R of the fourth embodiment is mainly different from the worm reducer 15 of the first embodiment of FIG.

That is, the worm speed reducer 15R includes a spring seat forming member 52R as a receiving seat forming member fixed to the end surface 43b of the outer ring 43 of the second bearing 34. The spring seat forming member 52R may be formed in the same cross-section D shape as the spring seat forming portion 52 of the first embodiment of FIG.

The spring seat forming member 52R includes a flat surface 52Ra on which a first spring seat 55R (first receiving seat) is formed, and a mounting surface 52Rb along the end surface 43b of the outer ring 43.

On the flat surface 52Ra, a concave portion 56R is formed as a spring end support portion. The recess 56R has a first spring seat 55R as a first receiving seat and a first spring guide 57R as a first restraining portion.

That is, a first spring seat 55R that receives the first end 71 of the compression coil spring 70 is formed by the bottom of the recess 56R. The first spring seat 55R is disposed on the outer side X2 of the outer ring 43 in the axial direction. Further, a first spring guide 57R as a first restraining portion is formed by the inner wall surface of the recess 56R. The first spring guide 57R restrains the movement of the first end portion 71 of the compression coil spring 70 in a direction intersecting with the urging direction (second direction Y2).

A fixed protrusion 52Rc protruding from the mounting surface 52Rb is formed. The spring seat forming member 52R is fixed to the outer ring 43 by the fixing protrusion 52Rc being press-fitted and fixed in a fixing hole 43c provided in the end surface 43b of the outer ring 43.

The housing holding hole 61 directly guides the outer ring 43 of the second bearing 34 in the first direction Y1 and the second direction Y2. That is, the bearing holder used in the first embodiment is abolished.

In the constituent elements of the fourth embodiment in FIG. 10, the same reference numerals as those in the first embodiment in FIG. 2 are assigned to the same constituent elements as those in the first embodiment in FIG. is there.

In the fourth embodiment, the structure can be simplified and the cost can be reduced.

Although not shown, the spring seat forming member 52R of the fourth embodiment may be applied to the second embodiment of FIG. 5 or the third embodiment of FIG. Although not shown, the spring seat forming member 52R may be formed integrally with the outer ring 43 of the second bearing 34 with a single material.
(Fifth embodiment)
FIG. 11 schematically shows the configuration of the urging portion of the fifth embodiment of the present invention. 5th Embodiment has shown the example which applied compression springs other than a compression coil spring as an urging | biasing member with respect to 1st Embodiment.

Specifically, in the fifth embodiment, a compression spring unit 90 as a compression spring includes a pair of torsion springs 91 arranged in parallel and symmetrically. The pair of torsion springs 91 are interposed between the housing 17 and the first spring seat 55 of the spring seat forming portion 52.

Each torsion spring 91 includes a coil portion 92 and a pair of

arms

93 and 94. The coil unit 92 connects the pair of

arms

93 and 94. The pair of

arms

93 and 94 are inclined in directions opposite to each other. An end 93 a of one arm 93 is received by the second spring seat 65 of the housing 17. The end 94 a of the other arm 94 is received by the first spring seat 55 of the spring seat forming portion 52. In FIG. 11, the spring seats 55 and 65 are shown in a simplified manner. The spring seats 55 and 65 may be formed by recesses.

The compression spring unit 90 including the pair of torsion springs 91 expands and contracts in a pantograph shape. The compression spring unit 90 is interposed between the first spring seat 55 of the spring seat forming portion 52 and the second spring seat 65 of the housing 17 in a state shortened from the free state. The compression spring unit 90 in the shortened state generates a pressing biasing force in the extending direction (second direction Y2) by the repulsive force of the coil portion 92 that is torsionally deformed, and the spring seat forming portion 52 is moved in the second direction Y2 by the pressing biasing force. Press to bias.

Although not shown, the configuration of the urging portion of the fifth embodiment may be applied to the second to fourth embodiments.
(Sixth embodiment)
FIG. 12 schematically shows the configuration of the urging portion of the sixth embodiment of the present invention. In the sixth embodiment, an example is shown in which a compression spring other than the compression coil spring is applied as the biasing member to the first embodiment.

Specifically, in the sixth embodiment of FIG. 12, a compression spring unit 100 as a compression spring includes a pair of leaf springs 101 arranged in parallel and symmetrically. The pair of leaf springs 101 are bent in a mountain shape so as to protrude outward in opposite directions. The pair of leaf springs 101 are interposed between the second spring seat 65 of the housing 17 and the first spring seat 55 of the spring seat forming portion 52.

Each leaf spring 101 includes a bent portion 102 serving as a top portion and a pair of plate-

like arms

103 and 104. The pair of

arms

103 and 104 extend from the bent portion 102 while being inclined in opposite directions. The end 103 a of one arm 103 is received by the second spring seat 65 of the housing 17. The end 104 a of the other arm 104 is received by the first spring seat 55 of the spring seat forming portion 52.

The compression spring unit 100 including a pair of leaf springs 101 expands and contracts in a pantograph shape. The compression spring unit 100 is interposed between the first spring seat 55 of the spring seat forming portion 52 and the second spring seat 65 of the housing 17 in a state shortened from the free state. The compression spring unit 100 in the shortened state generates a pressing biasing force in the extension direction (second direction Y2) by the repulsive force of the bending portion 102 that is bent and deformed so that the bending angle becomes small, and the spring seat is generated by the pressing biasing force. The forming portion 52 is pressed and biased in the second direction Y2.

Although not shown, the configuration of the urging portion of the sixth embodiment may be applied to the second to fourth embodiments.
(Seventh embodiment)
FIG. 13 schematically shows the configuration of the urging portion of the seventh embodiment of the present invention. 7th Embodiment has shown the example which applied compression springs other than a compression coil spring as an urging | biasing member with respect to 1st Embodiment.

Specifically, in the seventh embodiment of FIG. 13, a compression spring unit 110 as a compression spring includes a ring spring 111 wound around a plurality of strips. The plurality of ring springs 111 are formed of a continuous member (for example, a metal wire).

Each ring spring 111 includes a first portion 112 and a second portion 113. The first portion 112 is inserted through the first insertion hole 67 a of the spring seat forming portion 67 of the housing 17. The second portion 113 is inserted through the second insertion hole 52Sa of the spring seat forming portion 52S. Each

part

112, 113 may be fixed to the corresponding insertion hole 67a, 52Sa. Although not shown in FIG. 11, the spring seat forming portion 52 S is provided integrally with the outer ring 43 (not shown in FIG. 13) of the second bearing 34.

The inner surfaces of the insertion holes 67a and 52Sa constitute spring seats (receiving seats) for receiving the corresponding

portions

112 and 113 of the ring springs 111, respectively. The ring spring 111 is interposed between the spring seat forming portion 67 and the spring seat forming portion 52S in a state of being compressed and deformed so that the first portion 112 and the second portion 113 approach from the free state. Each ring spring 111 presses and urges the spring seat forming portion 52S in the second direction Y2 with an elastic restoring force against compression deformation.

Although not shown, the configuration of the urging portion of the seventh embodiment may be applied to the second to fourth embodiments.
(Eighth embodiment)
FIG. 14 schematically shows the configuration of the urging portion of the eighth embodiment of the present invention. In the eighth embodiment, an example is shown in which a tension spring other than the tension coil spring is applied as the biasing member to the third embodiment of FIG.

Specifically, in the eighth embodiment of FIG. 14, a tension spring unit 120 as a tension spring includes a ring spring 121 wound around a plurality of strips. The plurality of ring springs 121 are formed of a continuous member (for example, a metal wire).

Each ring spring 121 includes a first portion 122 and a second portion 123. The first portion 122 is inserted through the first insertion hole 68 a of the spring seat forming portion 68 of the housing 17. The second portion 123 is inserted through the second insertion hole 52Ta of the spring seat forming portion 52T. Each part 122,123 may be fixed to the corresponding insertion hole 68a, 52Ta. The spring seat forming portion 52T is provided integrally with the outer ring 43 (not shown in FIG. 14) of the second bearing 34.

The inner surfaces of the insertion holes 68a and 52Ta constitute spring seats (reception seats) for receiving the corresponding

portions

122 and 123 of the ring springs 121, respectively. The ring spring 121 is interposed between the spring seat forming portion 68 and the spring seat forming portion 52T in a state in which the first portion 122 and the second portion 123 are pulled and deformed away from the free state. Each ring spring 121 pulls and biases the spring seat forming portion 52T in the second direction Y2 with an elastic restoring force against tensile deformation.

Although not shown, the configuration of the urging portion of the eighth embodiment may be applied to the second to fourth embodiments.
(Ninth embodiment)
FIG. 15 is a cross-sectional view of a main part of a worm speed reducer 15S according to the ninth embodiment of the present invention. The worm reducer 15S of the ninth embodiment is mainly different from the worm reducer 15 of the first embodiment of FIG.

The worm reducer 15S includes a spacer 130 that regulates the set length SL of the compression coil spring 70. The spacer 130 is made of, for example, a cylindrical pin (shaft-shaped body). The spacer 130 and the compression coil spring 70 are arranged in series. The spacer 130 includes a first end 131 and a second end 132 disposed on the opposite sides in the axial direction.

A support hole 17 b as a support portion is provided on the inner surface of the housing portion 17 a of the housing 17. The first end 131 is supported by being fitted to the inner periphery 17c of the support hole 17b. The first end 131 is received by the bottom 17d of the support hole 17b. The support hole 17b has a depth DL.

The second end 132 includes a second spring seat 133 (second receiving seat) that receives the second end 72 of the compression coil spring 70 on the opposite side of the first spring seat 55 (first receiving seat).

Further, the second end portion 132 is provided with a connection portion that connects the second end portion 72 of the compression coil spring 70. Specifically, as the connection portion, a connection protrusion 134 that protrudes outward in the axial direction of the spacer 130 from the second end portion 132 is extended. The connection protrusion 134 is fitted to the inner diameter portion of the second end portion 72 of the compression coil spring 70 to connect the compression coil spring 70. The connection protrusion 134 supports the inner diameter portion of the second end portion 72 of the compression coil spring 70. The connection protrusion 134 constitutes a spring guide as a second restraining portion that restrains the movement of the second end portion 72 of the compression coil spring 70 in a direction intersecting the urging direction (second direction Y2).

In this embodiment, the set length SL of the compression coil spring 70 can be easily adjusted by changing the specification of the spacer 130 (for example, the length of the pin). Further, the set length SL of the compression coil spring 70 can be easily adjusted by changing the depth DL of the support hole 17 b of the housing 17.

Although not shown, instead of the connection protrusion 134, a connection hole that fits into the outer diameter portion of the second end 72 of the compression coil spring 70 is provided in the second end 132 as the connection. Also good. In this case, the inner periphery of the connection hole constitutes a spring guide as a second restraining portion that supports the outer diameter portion of the second end portion 72 of the compression coil spring 70.
(10th Embodiment)
FIG. 16 is a cross-sectional view of a main part of a worm reduction gear 15T according to the tenth embodiment of the present invention. FIG. 17 is a schematic view of a structure for guiding the compression coil spring 70 in the tenth embodiment.

The worm reducer 15T according to the tenth embodiment shown in FIGS. 16 and 17 is mainly different from the worm reducer 15S according to the ninth embodiment shown in FIG. The spacer 130T of the tenth embodiment has the same configuration as the configuration in which the connection protrusion 134 is removed from the spacer 130 of the ninth embodiment. The spacer 130T receives the second end 72 of the compression coil spring 70 by a spring seat 133T (second receiving seat) having a flat surface.

The lid member 44T includes a disk-shaped lid member main body 44a, a support guide 44b as a pair of support portions, and an annular flange 44c.

The pair of support guides 44b are extended on the back surface of the lid member main body 44a. As shown in FIG. 17, the pair of support guides 44b are formed in a plate shape extending parallel to the first direction Y1, and are separated from each other. A part of the spacer 130T and a part of the compression coil spring 70 are disposed between the pair of support guides 44b.

Between the pair of support guides 44b, the mutual displacement of the spacer 130T and the compression coil spring 70 arranged in series is regulated. The pair of support guides 44b are springs as restraining portions that support the outer diameter portion of the compression coil spring 70 so as to restrain the movement of the compression coil spring 70 in the direction intersecting the urging direction (second direction Y2). It constitutes a guide.

The annular flange 44c extends on the outer periphery of the lid member main body 44a. The annular flange 44c has an angular cross section, and is fitted into the end opening of the accommodating portion 17a.

In the constituent elements of the tenth embodiment shown in FIGS. 16 and 17, the same reference numerals as the constituent elements of the ninth embodiment in FIG. It is attached.

In the tenth embodiment, the same effects as in the ninth embodiment can be obtained. Although not shown, the pair of support guides may be provided on another member fixed to the housing 17 instead of the lid member 44T.
(Eleventh embodiment)
FIG. 18 is a cross-sectional view of a main part of a worm reduction gear 15U according to the eleventh embodiment of the present invention. The worm reducer 15U of the eleventh embodiment is mainly different from the worm reducer 15P of the second embodiment of FIG.

The worm reduction gear 15U includes a spacer 130U that regulates the set length SL of the compression coil spring 70. The spacer 130U is made of, for example, a cylindrical pin (shaft-shaped body). The spacer 130U and the compression coil spring 70 are arranged in series. The spacer 130 U includes a first end 131 U and a second end 132 disposed on the opposite sides in the axial direction.

The screw hole 88 which provides the connection hole as a support part is provided in the inner surface of the main-body part 81U of the interposition member 80U hold | maintained by the housing 17. As shown in FIG.

The spacer 130U includes a screw protrusion 135 as a connection protrusion that protrudes outward in the axial direction of the spacer 130U from the first end 131U. The spacer 130U is supported by the interposed member 80U by screwing the screw protrusion 135 into the screw hole 88. The first end 131U forms a positioning step 136 around the screw protrusion 135. The positioning step 136 abuts against the inner surface of the main body 81U of the interposed member 80U, so that the spacer 130U is positioned in the axial direction of the spacer 130U (the pin length direction) with respect to the interposed member 80U.

The configuration of the second end 132 of the spacer 130U is the same as the configuration of the second end 132 of the spacer 130 of the ninth embodiment in FIG.

In the constituent elements of the eleventh embodiment of FIG. 18, the same constituent elements as the constituent elements of the second embodiment of FIG. 5 and the same constituent elements of the ninth embodiment of FIG. The same reference numerals as the reference numerals of the elements and the constituent elements of the ninth embodiment are given.

In the eleventh embodiment, the set length SL of the compression coil spring 70 can be easily adjusted by changing the specification of the spacer 130U (for example, the length of the pin).

Although not shown, the outer peripheral thread portion of the screw protrusion 135 as the connection protrusion and the inner peripheral thread portion of the screw hole 88 as the connection hole are abolished, and the shaft-shaped connection protrusion is press-fitted into the connection hole. You may make it do.
(Twelfth embodiment)
FIG. 19 is a cross-sectional view of a main part of a worm reduction gear 15V according to the twelfth embodiment of the present invention. 20 is a cross-sectional view taken along the line XX-XX in FIG. FIG. 21 is an exploded perspective view of a main part of the worm speed reducer 15V. FIG. 22 is a schematic cross-sectional view of the structure around the spring seat.

The worm reducer 15V of the twelfth embodiment of FIG. 19 is mainly different from the worm reducer 15 of the first embodiment of FIG.

The housing 17V is formed with a holding hole 61V that is a through hole in the axial direction X that communicates with the housing portion 17a. The bearing holder 50V, the compression coil spring 70V as an urging member, and the buffer member 140 are accommodated in the holding hole 61V. The bearing holder 50V includes a main body 51V and a spring seat forming portion 52V as a receiving seat forming member. The bearing holder 50 V holds the second bearing 34.

The holding hole 61 V includes a first portion 151 and a second portion 152 disposed on the outer side X 2 in the axial direction of the first portion 151. The first portion 151 has an ellipse or a cross-sectional shape that approximates an ellipse.

In the holding hole 61V, a step portion 153 is formed between the first portion 151 and the second portion 152 so as to face the bearing holder 50V (specifically, the main body portion 51V) from the axially outer side X2. That is, the housing 17V forms a step portion 153 adjacent to the axially outward X2 of the bearing holder 50V. The dropout of the bearing holder 50V from the second bearing 34 is suppressed by the step portion 153 of the housing 17V.

If the lid member 44 functions to prevent the bearing holder 50V from coming off, it is necessary to improve the strength of the lid member 44 itself or to improve the strength of attaching the lid member 44 to the holding hole 61V. There is. For this reason, manufacturing cost rises. On the other hand, in this embodiment, since the step part 153 is provided in the strong housing 17V, the function of preventing the bearing holder 50V from falling off can be achieved at low cost.

As shown in FIG. 20, the inner surface of the second portion 152 has a guide portion 64V composed of a pair of flat surfaces extending in parallel with the biasing direction (second direction Y2) of the compression coil spring 70V. In addition, the inner surface of the second portion 152 includes a first facing portion 161 and a second facing portion 162 that face the biasing direction (second direction Y2) of the compression coil spring 70V. The 1st opposing part 161 is formed in the flat surface orthogonal to the urging | biasing direction of the compression coil spring 70V. The 2nd opposing part 162 is formed in the circular arc surface, for example.

As shown in FIG. 19, in the bearing holder 50V, the main body portion 51V and the spring seat forming portion 52V are integrally formed of a resin material such as polyamide resin. The main body 51V is accommodated in the first portion 151 of the holding hole 61V. The outer ring 43 of the second bearing 34 is press-fitted into the main body 51V. The spring seat forming portion 52V is accommodated in the second portion 152 of the holding hole 61V.

20 and 21, the main body 51V includes a ring part 51Va into which the outer ring 43 is press-fitted, and an end wall part 51Vb provided at one end of the ring part 51Va. The spring seat forming portion 52V has a block shape that protrudes axially outward X2 from the end wall portion 51Vb.

As shown in FIG. 19, a first stopper portion 170 that restricts the amount of movement of the bearing holder 50V in the first direction Y1 is formed on the inner surface of the first portion 151 of the holding hole 61V on the first direction Y1 side. ing. The first stopper portion 170 faces the outer periphery of the ring portion 51Va of the main body portion 51V of the bearing holder 50V through the second gap S20.

As shown in FIGS. 20 and 21, the outer surface of the spring seat forming portion 52V has a first surface 181, a second surface 182, a pair of guided portions 54V, and an end surface 183. The second surface 182 faces the second facing portion 162 of the second portion 152 of the holding hole 61V via the first gap S10.

The first surface 181 is opposed to the first facing portion 161 of the second portion 152 of the holding hole 61V through the buffer member 140. The buffer member 140 is disposed between the housing 17V and the spring seat forming portion 52V, and is sandwiched between the first surface 181 of the housing 17V and the first facing portion 161 of the spring seat forming portion 52V. Further, as shown in FIG. 19, the buffer member 140 is disposed on the axially outer side X 2 of the second bearing 34.

Temporarily, when the buffer member 140 is disposed radially outward of the second bearing 34, the inner diameter of the accommodating portion 17a that accommodates the worm shaft 18 in the housing 17V is increased. For this reason, there exists a possibility that the 2nd bearing 34 may enlarge, or the housing 17V may enlarge. On the other hand, in this embodiment, such a situation does not occur and the increase in size of the housing 17V can be suppressed. The buffer member 140 only needs to be disposed on at least one axially outward X2 of the second end 18b of the worm shaft 18 and the second bearing 34.

When the second end portion 18b of the worm shaft 18 is displaced in the first direction Y1, the first facing portion 161 approaches the first surface 181 and the buffer member 140 is compressed. At the same time, the outer periphery of the ring portion 51Va of the main body 51V of the bearing holder 50V approaches the first stopper portion 170 by an amount equal to the compression amount of the buffer member 140.

Here, the distance F (corresponding to the thickness of the buffer member 140) between the first surface 181 and the first facing portion 161 is set to be larger than the gap amount E of the second gap S20 (F> E). For this reason, at the normal time, the bearing holder 50B does not contact the housing 17V, and the generation of hitting sound is suppressed.

On the other hand, when a large input is applied from the worm wheel 19 side to the worm shaft 18 and the buffer member 140 is compressed by a predetermined amount, the outer periphery of the ring portion 51Va of the body portion 51V of the bearing holder 50V is applied to the first stopper portion 170. Abut. Thereby, excessive compression of, for example, the rubber member that forms the buffer member 140 is suppressed, so that occurrence of sag of the rubber member is suppressed.

Temporarily, when the buffer member 140 is disposed on a stopper part that contacts the first stopper part 170, a structure in which the buffer member 140 is integrally attached to the stopper part to form a unit is required. On the other hand, in this embodiment, since the buffer member 140 is disposed at a position separated from the first stopper portion 170, a structure in which the buffer member 140 is integrally attached to the stopper component to form a unit is not required.

As shown in FIG. 20, the pair of guided portions 54V is along the pair of guide portions 64V, respectively. The pair of guide portions 64V allows the bearing holder 50V to move in the first direction Y1 and the second direction Y2, while rotating the bearing holder 50V and moving in the direction orthogonal to the first direction Y1 and the second direction Y2. Is limiting.

The spring seat forming portion 52V forms an accommodating portion 58 that accommodates the compression coil spring 70V. As shown in FIG. 21, the accommodating part 58 is open | released in the axial direction outward X2 and the 1st direction Y1. The accommodating portion 58 has openings in the end surface 183 and the first surface 181.

As shown in FIG. 22, the spring seat forming portion 52V has a first spring seat 55V as a first receiving seat and a spring guide 60 as a first restraining portion. The spring seat forming portion 52 V forms a recess 59 as a spring end support portion on the bottom 58 a of the housing portion 58. As shown in FIG. 22, the recess 59 has a first spring seat 55V as a first receiving seat and a spring guide 60 as a first restraining portion. A first spring seat 55 V is formed by the bottom of the recess 59. A spring guide 60 as a first restraining portion is formed by the inner wall surface of the recess 59.

The first spring seat 55V receives the first end 71V of the compression coil spring 70V. The first spring seat 55V receives the biasing load of the compression coil spring 70V.

19, the first spring seat 55V is disposed on the end surface 18d of the second end 18b of the worm shaft 18 so as to be adjacent to the axial direction X. As shown in FIG.

In the bearing holder 50V fitted to the outer ring 43 of the second bearing 34, the spring seat forming portion 52V is caused by a temperature change as the distance from the central axis C1 (the center of the second bearing 34) of the worm shaft 18 increases radially outward. The dimensional change tends to increase. On the other hand, the first spring seat 55V adjacent to the axially outward X2 of the end face 18d of the second end portion 18b is disposed at a position relatively close to the central axis C1 in the radial direction. For this reason, even if the dimension of the spring seat formation part 52V changes with temperature changes, the change of the position of the 1st spring seat 55V is small. Therefore, the set length of the compression coil spring 70V is difficult to change, and the bias load is stabilized.

The spring guide 60 restrains the movement of the first end portion 71V of the compression coil spring 70V in the direction intersecting the urging direction (second direction Y2) of the compression coil spring 70V. The spring guide 60 guides the expansion and contraction of the compression coil spring 70V.

As shown in FIG. 19, the buffer member 140 is arranged on the second end 18b of the worm shaft 18 and at least one axially outward X2 of the second bearing 34. As shown in FIG. 20, the buffer member 140 is disposed between the spring seat forming portion 52V and the housing 17V. The housing 17V forms a second spring seat 161V as a second receiving seat for receiving the second end 72V of the compression coil spring 70V in the first facing portion 161 of the second portion 152 of the holding hole 61V.

As shown in FIG. 21, the buffer member 140 includes a rubber member. The buffer member 140 is formed, for example, in a plate shape. The buffer member 140 includes a spring guide 141 as a second restraining portion. Specifically, the buffer member 140 forms an insertion hole 142 through which the second end 72V of the compression coil spring 70V is inserted. A spring guide 141 that supports the outer diameter of the second end portion 72 V is formed by the inner surface of the insertion hole 142. The spring guide 141 restrains the movement of the second end portion 72V in the direction intersecting the urging direction (second direction Y2) of the compression coil spring 70V.

The movement of the

corresponding end portions

71V and 72V of the compression coil spring 70V is restrained by the spring guide 60 as the first restraining portion and the spring guide 141 as the second restraining portion. For this reason, buckling and position shift of compression coil spring 70V are controlled. Further, the intermediate portion between both end portions 71 V and 72 V of the compression coil spring 70 V is suppressed from being displaced by the inner surface of the accommodating portion 58.

The buffer member 140 has an opening 143 that opens the insertion hole 142 toward the end wall 51Vb of the main body 51V of the bearing holder 50V. The procedure for assembling the worm reducer 15V is as follows.

First, the second bearing 34 and the bearing holder 50V attached to the second end portion 18b of the worm shaft 18 are assembled into the holding hole 61V from the housing portion 17a side of the housing 17V.

Next, the compression coil spring 70V is interposed between the spring seat 161V of the first facing portion 161 of the second portion 152 of the holding hole 61V and the first spring seat 55V of the spring seat forming portion 52V of the bearing holder 50V. Incorporated into the housing 58. In this state, the first end portion 71V of the compression coil spring 70V is restrained from moving in the direction intersecting the biasing direction (second direction Y2) by the spring guide 60 as the first restraining portion formed of the inner surface of the recess 59. Is done.

Since the accommodating portion 58 is opened to the axially outward X2 side, the compression coil spring 70V can be incorporated into the accommodating portion 58 from the axially outward X2 side.

Next, the buffer member 140 is incorporated between the first facing portion 161 of the second portion 152 of the holding hole 61V and the first surface 181 of the spring seat forming portion 52V of the bearing holder 50V from the axially outward X2 side. . At this time, the second end 72V of the compression coil spring 70V is introduced into the insertion hole 142 through the opening 143 of the buffer member 140. In this state, the second end portion 72V of the compression coil spring 70V is moved in a direction intersecting the biasing direction (second direction Y2) by the spring guide 141 (second restraining portion) formed by the inner surface of the insertion hole 142. Be bound.

Since the buffer member 140 is provided with the opening 143 through which the insertion hole 142 is opened, the buffer member 140 can be substantially incorporated from the axially outward X2 side after the compression coil spring 70V is assembled. Become.

Next, the lid member 44 is attached to the housing 17V, and the end portion of the holding hole 61V in the axial direction X2 is closed by the lid member 44. Thereby, with respect to the axial direction X, the buffer member 140 is interposed between the lid member 44 and the end wall portion 51Vb of the main body portion 51V of the bearing holder 50V. For this reason, the buffer member 140 is positioned in the axial direction X.

Further, the buffer member 140 is interposed between the pair of guide portions 64V of the second portion 152 of the holding hole 61V in the direction orthogonal to both the axial direction X and the first direction Y1. For this reason, the buffer member 140 is positioned with respect to a direction orthogonal to both the axial direction X and the first direction Y1.
(13th Embodiment)
FIG. 23 is a cross-sectional view of a main part of a worm speed reducer 15W according to a thirteenth embodiment of the present invention. FIG. 24 is an exploded perspective view of a main part of the worm speed reducer 15W.

The worm reducer 15W of the thirteenth embodiment shown in FIGS. 23 and 24 is mainly different from the worm reducer 15V of the twelfth embodiment shown in FIGS. 19 and 21 in the following.

23 and 24, the bearing holder 50W of the worm reduction gear 15W includes a main body 51W and a spring seat forming portion 52W as a receiving seat forming member. The main body 51W and the spring seat forming portion 52W are integrally formed of a resin material such as polyamide resin. The main body 51W includes a fitting part 51We, an end wall part 51Wf, and a pair of flanges 51Wg and 51Wh.

The fitting portion 51We is formed in a C shape that fits at least a half circumference of the outer circumference 43a of the outer ring 43 of the second bearing 34. For this reason, the 2nd bearing 34 can be assembled | attached from the radial direction with respect to fitting part 51We. The C-shape formed by the fitting portion 51We is open toward the second direction Y2 (biasing direction). The compression coil spring 70V urges the bearing holder 50W in the direction in which the C-shape of the fitting portion 51We opens, so that the fitting portion 51We does not come off from the second bearing 34.

The pair of flanges 51Wg and 51Wh are extended radially inward from both ends in the axial direction X of the fitting portion 51We. The pair of flanges 51Wg and 51Wh are in contact with the pair of end surfaces 43b of the outer ring 43 of the second bearing 34, respectively. One flange 51Wh has a rib shape adjacent to the end wall 51Wf of the main body 51W.

The spring seat forming portion 52W is different from the spring seat forming portion 52V of the twelfth embodiment only in that the second surface 182W is formed on a flat surface parallel to the first surface 181.

In the constituent elements of the thirteenth embodiment shown in FIGS. 23 and 24, the same reference numerals as the constituent elements of the twelfth embodiment are given to the same constituent elements as those of the twelfth embodiment shown in FIGS. It is attached.

In this embodiment, the same effect as that of the twelfth embodiment is obtained. Further, the following effects are achieved. It is not necessary to press-fit the second bearing 34 into the C-shaped fitting portion 51We of the bearing holder 50W. Therefore, the occurrence of creep on the fitting surface (the inner surface of the fitting portion 51We) due to the press-fitting can be suppressed, and the drop of the bearing holder 50W from the second bearing 34 can be suppressed.

The bearing holder 50W holds the outer ring 43 of the second bearing 34 by the C-shaped fitting portion 51We and the pair of flanges 51Wg and 51W. For this reason, even if the bearing holder 50W undergoes a temperature change or a dimensional change due to water absorption, the bearing holder 50W can be prevented from dropping off from the second bearing 34.

Further, although the fitting portion 51We does not press-fit the second bearing 34, the pair of flanges 51Wg and 51Wh are in contact with the pair of end surfaces 43b of the outer ring 43 of the second bearing 34. For this reason, even if the compression coil spring 70V exerts a moment force in the direction in which the bearing holder 50W is tilted with respect to the second bearing 34, the pair of flanges 51Wg suppresses the tilt of the bearing holder 50W with respect to the second bearing 34. The Accordingly, it is possible to prevent the bearing holder 50 W from dropping from the second bearing 34.

The bearing holder 50W includes a C-shaped fitting portion 51We. The C-shaped fitting portion 51We is open toward the worm wheel 19 side. For this reason, even if the worm shaft 18 is downsized in the axial direction X so that the second end portion 18b of the worm shaft 18 approaches the first end portion 18a, the bearing holder 50W does not have a possibility of interfering with the worm wheel 19. . The worm speed reducer 15W can be reduced in size with respect to the axial direction X of the worm shaft 18 as much as possible.
(14th Embodiment)
FIG. 25 is a cross-sectional view of a main part of a worm reduction gear 15X according to the fourteenth embodiment of the present invention. FIG. 26 is a cross-sectional view of part of the main part of the worm reduction gear 15X. FIG. 27 is a perspective view of the subassembly SA of the worm speed reducer 15X, and FIG. 28 is a cross-sectional view of the subassembly SA. FIG. 29 is an exploded perspective view of a main part of the subassembly SA. 30 is an exploded perspective view from one direction of the subassembly SA, and FIG. 31 is an exploded perspective view from another direction of the subassembly SA.

The worm reducer 15X according to the fourteenth embodiment shown in FIGS. 25 to 31 is mainly different from the worm reducer 15W according to the thirteenth embodiment shown in FIGS.

As shown in FIG. 25, a holding hole 61X is formed in the housing 17X. The holding hole 61X is a through hole in the axial direction X that communicates with the housing portion 17a. One end of the holding hole 61X (the end on the axially outward X2 side) is open. On the inner periphery 61Xc of the holding hole 61X, an enlarged diameter portion 61Xa is formed at the one end of the holding hole 61X. On the inner periphery 61Xc of the holding hole 61X, a stepped portion 61Xb is formed at the end of the enlarged diameter portion 61Xa on the worm shaft 18 side.

The worm speed reducer 15X includes a lid member 44X, a bearing holder 50X, a compression coil spring 70X as an urging member, and a buffer member 240.

27 and 28, the lid member 44X, the bearing holder 50X, the compression coil spring 70X, and the buffer member 240 constitute a pre-assembled subassembly SA. As shown in FIG. 25, the subassembly SA is accommodated and held in the holding hole 61X. At the time of assembling the worm speed reducer 15X, the subassembly SA is assembled into the holding hole 61X from one end side (the axially outward X2 side that is the open side) of the holding hole 61X.

The lid member 44X is fixed to the holding hole 61X of the housing 17X, and the bearing holder 50 is supported by the lid member 44X. That is, the holding hole 61X indirectly holds the bearing holder 50X via the lid member 44X. The bearing holder 50 X holds the second bearing 34. The compression coil spring 70X is interposed between the lid member 44X and the bearing holder 50X. As shown in FIG. 29, the buffer member 240 is a C-shaped member interposed between the housing 17 and the bearing holder 50X.

Specifically, as shown in FIG. 25, the buffer member 240 is interposed between the inner periphery 61Xc of the holding hole 61X of the housing 17 and the outer periphery of the bearing holder 50X facing the inner periphery 61Xc. Generation of contact hitting sound with the bearing holder 50X is suppressed. The buffer member 240 is made of elastic rubber or resin.

25, 30 and 31, the lid member 44X includes a lid member main body 44Xa, a key 44Xb as a guide portion, and a pair of engaging convex portions 44Xc. The lid member 44X is made of resin or metal. The lid member main body 44Xa is formed in a circular plate shape. The lid member main body 44Xa includes an outer periphery 44Xd, a first end surface 44Xe that is an inner surface (surface on the worm shaft 18 side), and a second end surface 44Xf that is an outer surface.

As shown in FIG. 25, the lid member main body 44Xa is press-fitted into the enlarged diameter portion 61Xa at the one end of the holding hole 61X to close the one end of the holding hole 61X. That is, the outer periphery 44Xd of the lid member main body 44Xa is press-fitted to the enlarged diameter portion 61Xa of the inner periphery 61Xc of the holding hole 61X. The lid member 44X is positioned in the axial direction X by the first end surface 44Xe of the lid member main body 44Xa coming into contact with the step portion 61Xb of the holding hole 61X.

As shown in FIG. 30, a key 44 Xb as a guide portion is formed to protrude from the first end surface 44 Xe of the lid member main body 44 Xa. Further, as shown in FIG. 31, a pair of engaging convex portions 44Xc are formed so as to protrude from the first end face 44Xe.

As shown in FIG. 30, the key 44Xb of the lid member 44X is composed of a T-shaped protrusion formed in a T shape when viewed from the urging direction (second direction Y2) of the compression coil spring 70X. The key 44Xb is an integral key formed integrally with the lid member main body 44Xa. The key 44Xb extends longitudinally in the second direction Y2.

The second end face 44Xf of the lid member main body 44Xa is formed with a rectangular groove 44Xp as a display portion for positioning the lid member 44X in the circumferential direction of the holding hole 61X when the subassembly SA is assembled into the holding hole 61X. . The rectangular groove 44Xp extends in the second direction Y2 in parallel with the key 44Xb. The rectangular groove 44Xp is aligned with, for example, a display portion (not shown) such as a recess provided in the peripheral portion of the holding hole 61X of the housing 17. As the display portion, a convex portion, a concave portion, a coating portion of paint, or the like can be used.

29, the bearing holder 50X includes a fitting portion 51X and an end wall-shaped spring seat forming portion 52X disposed in a portion on the axially outward X2 side of the fitting portion 51X. The bearing holder 50X is integrally formed of a resin material such as polyamide resin.

As shown in FIG. 26, the fitting portion 51X is formed in a C-shape that fits at least a half circumference of the outer periphery 43a of the outer ring 43 of the second bearing 34. The C-shape formed by the fitting portion 51X is open toward the second direction Y2 (worm wheel 19 side).

As shown in FIG. 29, a holding groove 51Xb extending in the circumferential direction is formed on the outer periphery 51Xa of the fitting portion 51X. The buffer member 240 is fitted and held in the holding groove 51Xb. The buffer member 240 includes a C-shaped main body 241 and angle-shaped engaging claws 242 that are formed at a pair of circumferential ends 241 a of the main body 241 and project inwardly.

As shown in FIGS. 27 and 29, the main body 241 has an escape portion 243 formed of a notch that avoids interference with the key 44Xb of the lid member 44X. As shown in FIG. 26, the engaging claw 242 is spaced radially outward from the outer ring 43 of the second bearing 34.

As shown in FIGS. 26 and 29, the C-shaped fitting portion 51X of the bearing holder 50X has an engagement recess 51Xd formed at a pair of circumferential end portions 51Xc. As shown in FIGS. 26 and 31, each engaging claw 242 of the buffer member 240 is hooked and engaged with the corresponding engaging recess 51Xd of the bearing holder 50X. Thereby, the buffer member 240 is held by the bearing holder 50X.

As shown in FIG. 25, a first stopper portion 170 is provided on the inner periphery 61Xc of the holding hole 61X at a portion on the first direction Y1 side of the fitting portion 51X of the bearing holder 50X. The first stopper 170 part faces the outer periphery 51Xa of the fitting part 51X of the bearing holder 50X via the second gap S20.

In the first direction Y1, the thickness of the buffer member 240 is larger than the gap amount of the second gap S20. When the worm shaft 18 is flipped up from the worm wheel 19 due to vibration or the like when traveling on a rough road, the first stopper portion 170 of the holding hole 61X contacts the outer periphery 51Xa of the fitting portion 51X, and the bearing holder 50X Excessive movement in the first direction Y1 is restricted. Thereby, deterioration of the compression coil spring 70X and damage to the worm wheel 19 are suppressed.

As shown in FIGS. 27 and 30, the spring seat forming portion 52X includes a key groove 52Xa as a guided portion that is key-coupled to the key 44Xb (guide portion) of the lid member 44X, and a first spring as a first receiving seat. And a seat 55X.

25, the first spring seat 55X is disposed on the end surface 18d of the second end 18b of the worm shaft 18 so as to be adjacent to the axial direction X. As shown in FIG. The first spring seat 55X is disposed at a position relatively close to the central axis C1 in the radial direction. For this reason, even if the dimension of the spring seat formation part 52X changes with temperature changes, the change of the position of the 1st spring seat 55X is small. Therefore, the set length of the compression coil spring 70X hardly changes, and the bias load is stabilized.

30, the first spring seat 55X is formed at the bottom of the keyway 52Xa in the second direction Y2, and receives the first end 71X of the compression coil spring 70X as shown in FIG. As shown in FIG. 30, the key groove 52Xa is a T-shaped groove formed in a T shape when viewed from the biasing direction (second direction Y2) of the compression coil spring 70X. The keyway 52Xa is opened toward the first direction Y1.

As shown in FIGS. 27 and 30, the key 44Xb (guide portion) of the lid member 44X is key-coupled with the key groove 52Xa (guided portion) of the bearing holder 50X, and the biasing direction (first direction) of the compression coil spring 70X is obtained. 2 direction Y2) and the movement of the bearing holder 50X in the direction opposite to the urging direction (first direction Y1) are guided.

As shown in FIGS. 25 and 28, the key 44Xb of the lid member 44X has a facing surface 44Xh facing the first spring seat 55X in the first direction Y1. The key 44Xb penetrates the opposing surface 44Xh and forms an accommodating portion 44Xj formed of a circular hole that accommodates a part of the compression coil spring 70X.

A second spring seat 44Xk as a second receiving seat for receiving the other end 72X of the compression coil spring 70X is disposed on the bottom of the housing portion 44Xj in the first direction Y1. A spring guide 44Xm that supports the outer diameter portion of the compression coil spring 70X and suppresses the collapse of the compression coil spring 70X is formed on the inner peripheral surface of the housing portion 44Xj.

As shown in FIG. 28, the pair of engaging convex portions 44Xc of the lid member 44X engage with the bearing holder 50X in the state of the subassembly SA, and apply the biasing load of the compression coil spring 70X via the bearing holder 50X. receive. Specifically, the engagement convex portion 44Xc engages with the end portion 52Xb on the second direction Y2 side (worm wheel 19 side) of the spring seat forming portion 52X.

As shown in FIGS. 25 and 28, the engaging surface 44Xn of the engaging convex portion 44Xc that engages with the end portion 52Xb of the spring seat forming portion 52X is displaced in the first direction Y1 toward the worm shaft 18 side. It is formed on the inclined surface.

Therefore, as shown in FIG. 28, in the sub-assembly SA before being assembled into the holding hole 61X, the urging force exerted on the engaging surface 44Xn by the compression coil spring 70X causes the end 52Xb of the spring seat forming portion 52X to move outward in the axial direction. Has a force component to urge X2. Thereby, since the separation of the end 52Xb from the engagement surface 44Xn can be suppressed, the state of the subassembly SA is stably maintained.

As shown in FIG. 25, in a state where the second bearing 34 of the second end portion 18b of the worm shaft 18 is fitted to the bearing holder 50X of the subassembly SA after being assembled into the holding hole 61X, compression is performed. The coil spring 70X is contracted, and the end 52Xb of the spring seat forming portion 52X is separated from the engagement convex portion 44Xc in the first direction Y1. For this reason, in the assembled state of the worm reduction gear 15X, the displacement of the second end portion 18b of the worm shaft 18 in the second direction Y2 is not hindered by the engagement convex portion 44Xc.

In the constituent elements of the fourteenth embodiment shown in FIGS. 25 to 31, the same reference numerals as the constituent elements of the thirteenth embodiment are given to the same constituent elements as those of the thirteenth embodiment shown in FIGS. It is attached.

According to the present embodiment, the bearing holder 50X, the lid member 44X, and the compression coil spring 70X can be collectively assembled into the holding hole 61X of the housing 17 as the subassembly SA, and the assemblability is improved. After the subassembly SA is assembled, the worm shaft 18 is incorporated into the housing portion 17a of the housing 17X from the second end portion 18b side (second bearing 34 side).

Also, the guide portion (key 44Xb) of the lid member 44X causes the second end portion 18b of the worm shaft 18 to be opposed to the biasing direction (second direction Y2) of the compression coil spring 70X and the biasing direction via the bearing holder 50X. It is possible to smoothly guide in the direction (first direction Y1).

In addition, the key 44Xb (guide portion) of the lid member 44X and the key groove 52Xa (guided portion) of the bearing holder 50X are combined with each other, and the second member of the worm shaft 18 is formed while unitizing the lid member 44X and the bearing holder 50X. The function of guiding the end 18b can be achieved.

As shown in FIG. 28, in the subassembly SA, the biasing load of the compression coil spring 70X is exerted on the lid member 44X and the bearing holder 50X, so that the lid member 44X, the bearing holder 50X, and the compression coil spring 70X are unitized. Can be achieved.

Further, since the subassembly SA includes the buffer member 240, the assemblability is further improved as compared with the case where the buffer member 240 is separately incorporated.

Further, the bearing holder 50X includes a C-shaped fitting portion 51X that opens to the worm wheel 19 side. For this reason, even if the worm shaft 18 is miniaturized in the axial direction X so that the second end portion 18b of the worm shaft 18 approaches the first end portion 18a, there is no possibility that the bearing holder 50X interferes with the worm wheel 19. The worm speed reducer 15X can be reduced in size with respect to the axial direction X of the worm shaft 18 as much as possible.

Further, it is not necessary to press-fit the second bearing 34 into the C-shaped fitting portion 51X of the bearing holder 50X. Therefore, the occurrence of creep on the fitting surface (the inner surface of the fitting portion 51X) due to the press-fitting can be suppressed, and the bearing holder 50X from falling off the second bearing 34 can be suppressed.

The present invention is not limited to each of the above-described embodiments, and instead of a compression spring or a tension spring, a rod-like elastic body made of resin or rubber may be used.

In each of the above embodiments, the electric power steering device 1 may be an electric power steering device that applies the power of the electric motor 14 to the pinion shaft 11.

DESCRIPTION OF SYMBOLS 1; 1P; 1Q ... Electric power steering device, 3 ... Steering wheel, 4 ... Steering mechanism, 5 ... Assist mechanism, 6 ... Steering shaft, 7 ... Column shaft, 11 ... Pinion shaft, 14 ... Electric motor, 14a ... Output shaft 15; 15P; 15Q; 15S; 15T; 15U; 15V; 15W; 15X ... Worm reducer, 17; 17V ... Housing, 17a ... Housing part, 17b ... Support hole (support part), 18 ... Worm shaft, 18a ... 1st end, 18b ... 2nd end, 18d ... End face, 19 ... Worm wheel, 20 ... Power transmission joint, 33 ... 1st bearing, 34 ... 2nd bearing, 40 ... Inner ring, 43 ... Outer ring, 43a ... Outer periphery , 43b ... end face, 44T; lid member, 44X ... lid member (member held by the housing), 44a; 44Xa ... lid member body, 44b ... support guide Support part), 44Xb ... key (guide part), 44Xc ... engagement convex part, 50; 50Q; 50V; 50W; 50X ... bearing holder, 51; 51V; 51W ... main body part, 51b ... outer periphery, 51c ... part, 51d ... Contact part, 51We; 51X ... Fitting part, 51Wf ... End wall part, 51Wg, 51Wh ... Flange, 52; 52Q; 52S; 52T; 52V; 52W; 52X ... Spring seat forming part (receiving seat forming member), 52Xa ... key groove (guided part), 53 ... fitting hole, 54; 54V ... guided part, 55; 55Q; 55V; 55X ... first spring seat (first receiving seat), 61; 61Q; 61V; Holding hole 62 ... inner surface, 64; 64V ... guide part, 65; 65Q ... second spring seat (second receiving seat), 70; 70V; 70X ... compression coil spring (compression spring, biasing member), 70Q ... tension coil Spring (tension 71, 72; 71Q, 72Q; 71V, 72V ... end, 80; 80U ... interposed member (member held by the housing), 81; 81U ... main body, 82 ... spring seat forming part (Receiving seat forming member), 83 ... holding hole, 84 ... guide portion, 85 ... second spring seat (second receiving seat), 86 ... inner surface, 88 ... screw hole (connecting hole as support portion), 90; 100 110: compression spring unit (compression spring), 120: tension spring unit (tension spring), 130: 130T: 130U ... spacer, 131; 131U ... first end, 132 ... second end, 133T: 133T ... spring Seat (second receiving seat), 134 ... connection protrusion (connection portion), 135 ... screw protrusion (connection protrusion), 140; 240 ... buffer member, 241 ... main body, 242 ... engagement claw, 141 ... spring guide (second) Restraint part), 142 ... insertion hole, 143 ... opening, C1 ... central axis of (worm shaft), C2 ... central axis of (worm wheel), D1 ... center distance, SA ... subassembly, X ... axial direction, X2 ... outside axial direction , Y1... First direction (the direction in which the center distance increases). (Opposite direction of urging direction), Y2 ... second direction (direction in which the distance between the cores decreases. Urging direction)

Claims

A housing;
A worm shaft housed in the housing and having a first end connected to an electric motor and a second end located on the opposite side of the first end;
A worm wheel meshing with the worm shaft;
A first bearing rotatably supporting the first end with respect to the housing;
A second bearing rotatably supporting the second end;
A receiving seat forming member provided on an outer ring of the second bearing, and forming a receiving seat disposed at an axially outer side of at least one of the second end portion and the second bearing;
Adjacent to at least one of the second end and the second bearing and disposed between the housing and the receiving seat, the worm shaft approaches the worm wheel so as to approach the worm wheel. A biasing member that biases the second end portion through the receiving seat forming member and the second bearing;
A worm speed reducer characterized by comprising:
2. The worm reducer according to claim 1, wherein the urging member includes a compression spring that urges the receiving seat toward the worm wheel.
3. The worm reducer according to claim 2, wherein the receiving seat is disposed closer to the worm wheel than a central axis of the worm shaft.
The bearing holder for holding the second bearing according to any one of claims 1 to 3,
The receiving seat forming member is a worm speed reducer provided integrally with the bearing holder.
5. The worm speed reducer according to claim 4, wherein the housing or the member held by the housing includes a guide portion that guides the movement of the bearing holder in a biasing direction of the biasing member and in a direction opposite to the biasing direction. Machine.
5. The housing according to claim 4, wherein the housing includes a holding hole that holds the bearing holder and is open at one end.
A subassembly including the bearing holder, a lid member fitted to the one end of the holding hole, and a compression spring as the urging means interposed between the bearing holder and the lid member is configured. Worm reducer.
7. The lid member according to claim 6, wherein the lid member is engaged with a guided portion of the bearing holder to guide the biasing direction of the biasing member and the movement of the bearing holder in a direction opposite to the biasing direction. Worm speed reducer including a guide.
8. The worm reducer according to claim 7, wherein the guide portion is key-coupled to the guided portion.
9. The engagement protrusion according to claim 6, wherein the lid member is engaged with the bearing holder in the state of the sub-assembly and receives a biasing load of the compression spring via the bearing holder. Worm speed reducer including parts.
10. The worm speed reducer according to claim 6, wherein the subassembly includes a buffer member interposed between the bearing holder and the housing.
5. The worm reducer according to claim 4, wherein the bearing holder includes a C-shaped fitting portion that fits on an outer periphery of the outer ring of the second bearing and opens to the worm wheel side.
5. The bearing holder according to claim 4, wherein the bearing holder includes a C-shaped fitting portion that fits on an outer periphery of the outer ring of the second bearing, and a pair of end surfaces of the outer ring of the second bearing that extend from the fitting portion. A worm reduction gear made of resin, including a pair of flanges that abut each other.
2. The worm speed reducer according to claim 1, further comprising a buffer member disposed axially outward of at least one of the second end portion and the second bearing and between the receiving seat forming member and the housing.
In Claim 13, the buffer member includes a rubber member,
A worm speed reducer configured such that the bearing holder contacts the housing when the rubber member is compressed by a predetermined amount.
In Claim 1, provided with a bearing holder that fits to the outer periphery of the outer ring of the second bearing and holds the second bearing,
The housing is a worm reduction gear including a step portion adjacent to the bearing holder in the axially outward direction.
In Claim 13, The said seat formation member contains the 1st restraint part which restrains movement of the end of the above-mentioned energizing member to the direction which intersects the energizing direction of the above-mentioned energizing member,
The buffer member includes a second restraining portion that restrains movement of the other end of the biasing member in a direction intersecting the biasing direction of the biasing member.
2. The worm reducer according to claim 1, wherein the receiving seat is disposed adjacent to an end face of the second end portion of the worm shaft.
The spacer according to any one of claims 1 to 17, further comprising a second receiving seat that receives the biasing member on a side opposite to the first receiving seat as the receiving seat, and that regulates a set length of the biasing member. Equipped with a worm reducer.
19. The worm reducer according to claim 18, further comprising a support portion that is provided on the housing or a member held by the housing and supports the spacer.
An electric power steering apparatus for transmitting the power of the electric motor to the steering shaft via the worm speed reducer according to any one of claims 1 to 19.