JP2013079023A - Steering device of rack-and-pinion type and bush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device of rack-and-pinion type capable of improving assembly workability of a bush in a configuration pressing a rack shaft against a pinion shaft by the bush.SOLUTION: In the steering device, the second bush 12 for supporting the rack shaft to be slidable includes a bush body 55 and an O-ring 56. The bush body 55, which assumes a C shape in a side view, is arranged between the rack shaft and a housing of the steering device. In the same body, a first groove 57 elongated circumferentially and a second groove 72 elongated axially in a position to avoid the first groove 57 are formed on an outer peripheral surface 55A. The O-ring 56 is fitted into the first groove 57 in such a manner as to partially protrude from the outer peripheral surface 55A of the bush body 55, and sandwiched between the bush body 55 and the housing to urge the rack shaft toward the pinion shaft via the bush body 55.

Description

  The present invention relates to a rack and pinion type steering device and a bush that supports a rack shaft of the steering device.

A rack and pinion type vehicle steering device is known. The steering device of Patent Document 1 includes a pinion shaft connected to the steering wheel, and a rack shaft that meshes with the pinion shaft and steers the wheel while sliding in the vehicle width direction according to steering of the steering wheel. .
The steering device includes a housing that houses a rack shaft, a cylindrical bush that is externally fitted to the rack shaft, and that elastically supports the rack shaft in this state, and a rack And a guide. The rack guide is urged by a pressure spring to urge the rack shaft to the pinion shaft, thereby reducing backlash at the meshing portion between the rack shaft and the pinion shaft. Therefore, it is possible to suppress so-called rattling noise in the meshing portion.

  Patent Document 2 proposes a configuration in which the rack guide is abolished and the rack shaft is urged to the pinion shaft by a bush (rack bush) in order to simplify the structure. This bush is cylindrical like the bush of patent document 1, and is provided one each at the axial direction both ends of the rack shaft. An annular groove extending in the circumferential direction is formed on the outer peripheral surface of the bush, and an O-ring is fitted in the annular groove. The rack shaft is elastically supported by the bush by compressing the O-ring between the bush and the inner peripheral surface of the housing.

  Of the pair of bushes at both axial ends of the rack shaft, the first bush is located closer to the pinion shaft than the other bush (second bush). An elastic member is provided on the outer peripheral surface of the first bush. The elastic member urges the rack shaft inserted into the first bush toward the pinion shaft with the second bush as a fulcrum. doing.

JP 2004-161117 A JP 2008-74218 A

  In the configuration described in Patent Document 2, since the bush is cylindrical, when the bush is inserted into the housing from the end opening of the housing, the O-ring externally fitted to the bush is arranged on the entire circumference. Over this, it must be compressed between the bush and the inner peripheral surface of the housing. In this case, since it is necessary to push the bush into the housing while compressing the entire O-ring, it is difficult to assemble the bush to the housing.

  The present invention has been made under such background, and a rack-and-pinion type steering device capable of improving the assembling property of the bush in the configuration in which the rack shaft is urged to the pinion shaft by the bush, and this The purpose is to provide a bush.

  The invention according to claim 1 includes a pinion shaft (7), a rack shaft (8) arranged in a direction intersecting with the pinion shaft, a housing (9) for accommodating these shafts, and the pinion in the housing. A rack-and-pinion type steering device (1) provided with two bushes (11, 12) arranged so as to sandwich the shaft and slidably supporting the rack shaft, wherein at least one of the two bushes One is a C-type in a side view, and is disposed between the rack shaft and the housing at one end (92) of the housing, and avoids the first groove (57) extending in the circumferential direction and the first groove. A bush main body (55) having a second groove (72) extending in the axial direction at the outer peripheral surface (55A) and a part of the second main groove (72) projecting from the outer peripheral surface of the bush main body are fitted into the first groove. , An elastic member (56) sandwiched between the bush main body and the housing and biasing the rack shaft toward the pinion shaft through the bush main body. This is a steering device of the type.

According to a second aspect of the present invention, the third groove (73) extending in the axial direction while being recessed toward the second groove side at a position coinciding with the second groove in the circumferential direction on the inner peripheral surface (55B) of the bush body. The rack and pinion type steering device according to claim 1, wherein the steering device is formed.
According to a third aspect of the present invention, there is provided the pinion shaft, a rack shaft disposed in a direction intersecting with the pinion shaft, a housing that accommodates these shafts, and the rack disposed with the pinion shaft interposed therebetween in the housing. A rack-and-pinion type steering device including two bushes for slidably supporting a shaft, wherein at least one of the two bushes is C-type in a side view, and the rack is provided at one end of the housing. A bushing body (57) disposed between the shaft and the housing and having a fitting groove extending in the circumferential direction formed on the outer peripheral surface and a notch (61) extending in the axial direction, and a part thereof The bush body is fitted in the fitting groove so as to protrude from the outer peripheral surface of the bush body, and is sandwiched between the bush body and the housing. And an elastic member that biases the rack shaft toward the pinion shaft, and a corner portion (70) intersecting the notch in the fitting groove is chamfered. It is an Andpinion type steering device.

The invention according to claim 4 is characterized in that the bush (12) having the C-shaped bush body in the side view is arranged at the end (92) on the pinion shaft side in the housing. The rack-and-pinion steering device according to any one of 1 to 3.
The invention according to claim 5 is a bush for supporting a rack shaft of a rack and pinion type steering device, which is a C-type in a side view, and avoids the first groove extending in the circumferential direction and the first groove. A second groove extending in the axial direction is formed on the outer peripheral surface, the bush main body through which the rack shaft is inserted on the inner peripheral surface side, and the first so that a part protrudes from the outer peripheral surface of the bush main body. A rack shaft bush including an elastic member fitted in a groove.

According to a sixth aspect of the present invention, a third groove extending in the axial direction while being depressed toward the second groove side is formed at a position coinciding with the second groove in the circumferential direction on the inner peripheral surface of the bush body. The rack shaft bush according to claim 5, characterized in that:
The invention according to claim 7 is a bush for supporting the rack shaft of the rack-and-pinion type steering device, which is C-type in a side view, and has an insertion groove formed in the outer circumferential surface extending in the circumferential direction. A notch extending in the axial direction is formed, a bush main body through which the rack shaft is inserted on the inner peripheral surface side, and an elastic member fitted into the fitting groove so that a part protrudes from the outer peripheral surface of the bush main body And a corner for intersecting the notch in the fitting groove is chamfered.

  In addition, in the above, the numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

  According to the first, third, fifth, and seventh aspects of the invention, in the bush having the C-shaped bush main body as viewed from the side, when the bush is assembled to the housing of the steering device, compared to the case where the bush main body is cylindrical. A portion that becomes resistance in the bush (a portion that is compressed between the bush main body and the inner peripheral surface of the housing in the elastic member) is reduced. Therefore, the bush can be easily and smoothly assembled to the housing. As a result, it is possible to improve the assembly of the bush.

  According to the second and sixth aspects of the invention, even if the second groove is not a notch penetrating the peripheral wall of the bushing body as in the bushing of the first and fifth aspects, the second groove is formed on the inner circumferential surface of the bushing body. By forming the third groove at a position coinciding with the groove, the bush can be easily bent, and the bush can be easily and smoothly assembled to the housing. Thereby, the further improvement of the assembly | attachment property of a bush can be aimed at.

  According to the fourth aspect of the present invention, the bush having the C-shaped bush main body as viewed from the side has the force point as a force point, the other bush as a fulcrum, and the meshing portion of the rack shaft and the pinion shaft between the force point and the fulcrum. The rack lever can be biased sufficiently and sufficiently toward the pinion shaft by the “lever principle” which is the operating point between them.

FIG. 1 is a schematic diagram showing a schematic configuration of a steering device 1 according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the rack and pinion mechanism 10 and its surroundings extracted from the steering device 1. 3A is an enlarged view around the first bush 11 in FIG. 2, and FIG. 3B is an enlarged view around the second bush 12 in FIG. 4A shows a state in which a high load is applied to the rack shaft 8 in FIG. 3A, and FIG. 4B shows a state in which a high load is applied to the rack shaft 8 in FIG. 3B. Indicates the state. FIG. 5 is a perspective view of the first bush 11. FIG. 6 is an exploded perspective view of the first bush 11. FIG. 7 is a perspective view of the second bush 12 according to the first embodiment. FIG. 8 is an exploded perspective view of the second bush 12 according to the first embodiment. FIG. 9A is a perspective view of the bush main body 55 with respect to the second bush 12 according to the first embodiment, as viewed from a direction different from FIG. 8, and FIG. 9B is a view from the outside in the radial direction. 9 (c) is a side view of the bush main body 55 as viewed from the outside in the axial direction, and FIG. 9 (d) is taken along the line AA in FIG. 9 (b). It is sectional drawing. FIG. 10A is a cross-sectional view of the housing 9 and shows a state immediately after the first bush 11 is assembled. FIG. 10B shows the housing 9 of FIG. It is a perspective view which shows a mode that the 2nd bush 12 is assembled | attached. FIG. 11 (a) shows a state immediately after the second bush 12 is assembled to the housing 9 in FIG. 10 (a), and FIG. 11 (b) is a cross-sectional view taken along line BB in FIG. 11 (a). It is sectional drawing in a line. FIG. 12 shows a state immediately after the rack shaft 8 is assembled to the housing 9 in FIG. FIG. 13A is a perspective view of the bush body 55 of the second bush 12 according to the second embodiment, and FIG. 13B is a side view of the bush body 55 as viewed from the outside in the radial direction. 13 (c) is a cross-sectional view taken along line CC of FIG. 13 (b). FIG. 14 is a perspective view of the second bush 12 according to the third embodiment. FIG. 15 is an exploded perspective view of the second bush 12 according to the third embodiment. FIG. 16A is a perspective view of the bush body 55 with respect to the second bush 12 according to the third embodiment, as viewed from a direction different from that of FIG. 15, and FIG. 16 (c) is a side view of the bush main body 55 as viewed from the outside in the axial direction, and FIG. 16 (d) is a sectional view taken along the line DD in FIG. 16 (b). It is sectional drawing.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a steering device 1 according to an embodiment of the present invention.
Referring to FIG. 1, a steering device 1 includes a steering member 2 such as a steering wheel, a steering shaft 3, a first universal joint 4, an intermediate shaft 5, a second universal joint 6, a pinion shaft 7, A rack shaft 8 and a housing 9 are mainly included. The steering shaft 3 is connected to the steering member 2. The steering shaft 3 and the intermediate shaft 5 are connected via the first universal joint 4. The intermediate shaft 5 and the pinion shaft 7 are connected via a second universal joint 6.

  A pinion 7 </ b> A is provided near the end of the pinion shaft 7. The rack shaft 8 has a columnar shape extending in the vehicle width direction (the left-right direction in FIG. 1 and may also be referred to as “axial direction X”). A rack 8 </ b> A is provided in an intermediate region in the axial direction X at one place on the outer peripheral surface of the rack shaft 8. The pinion shaft 7 is arranged in a crossing direction (vertical direction in FIG. 1) with the rack shaft 8 extending in the axial direction X, and the pinion 7A of the pinion shaft 7 and the rack 8A of the rack shaft 8 are engaged with each other. A rack and pinion mechanism 10 is configured by the pinion shaft 7 and the rack shaft 8. Therefore, the steering device 1 is a rack and pinion type steering device.

  The housing 9 is formed of a metal such as aluminum, has a hollow cylindrical shape that is long along the rack shaft 8 (axial direction X), and is fixed to a vehicle body (not shown). The rack shaft 8 is accommodated in the housing 9 and can linearly reciprocate along the axial direction X in this state. The pinion shaft 7 (pinion 7A) is accommodated in the housing 9 between both end portions in the axial direction X (a position biased to the right in FIG. 1). Of the both ends of the housing 9, the first end 91 (left end in FIG. 1) is relatively far from the pinion shaft 7, and the second end 92 (right end in FIG. 1) is on the pinion shaft 7. Relatively close. That is, the second end 92 is an end on the pinion shaft 7 side. The first bushing 11 is disposed at the first end 91, and the second bushing 12 is disposed at the second end 92.

  The first bush 11 and the second bush 12 are part of the steering device 1 and are disposed in the housing 9 so as to sandwich the pinion shaft 7 from the axial direction X. The rack shaft 8 is supported by the first bush 11 and the second bush 12, and is slidable in the axial direction X with respect to these bushes. The first bush 11 and the second bush 12 will be described in detail later.

Both end portions (in the axial direction X) of the rack shaft 8 accommodated in the housing 9 protrude to both outer sides of the housing 9, and a tie rod 14 is coupled to each end portion via a joint 13. Each tie rod 14 is connected to a wheel 15 via a corresponding knuckle arm (not shown).
When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted into a linear motion (slide) of the rack shaft 8 along the axial direction X by the pinion 7A and the rack 8A. Thereby, the steering of each wheel 15 is achieved.

  FIG. 2 is a schematic diagram showing the rack and pinion mechanism 10 and its surroundings extracted from the steering device 1. 3A is an enlarged view around the first bush 11 in FIG. 2, and FIG. 3B is an enlarged view around the second bush 12 in FIG. 4A shows a state in which a high load is applied to the rack shaft 8 in FIG. 3A, and FIG. 4B shows a state in which a high load is applied to the rack shaft 8 in FIG. 3B. Indicates the state.

In FIG. 2, the housing 9, the rack and pinion mechanism 10 (the pinion shaft 7 and the rack shaft 8), the first bush 11 and the second bush 12 are shown. Each of these will be described below.
As described above, the housing 9 has a hollow cylindrical shape, and the hollow portion 20 has a cylindrical shape having a central axis extending along the axial direction X. One end of the hollow portion 20 in the axial direction X is exposed to the outside (left outer side in FIG. 2) as the first opening 21 at the first end 91, and the other end of the hollow portion 20 in the axial direction X is the second end. In the portion 92, the second opening 22 is exposed to the outside (right outside in FIG. 2). The first opening 21 and the second opening 22 are both round holes having a diameter larger than that of the rack shaft 8.

  The inner peripheral surface 23 defining the hollow portion 20 in the housing 9 is, in the first end portion 91, in order from the side closer to the first opening 21, the outer inner peripheral surface 24, the annular convex portion 25, the annular groove 26, An inner inner peripheral surface 27 and a stepped portion 28 are included. The outer inner circumferential surface 24 is a circumferential surface having the same inner diameter as the first opening 21, and extends continuously from the first opening 21 to the second end 92 side (right side in FIG. 2). The annular convex portion 25 is a portion that protrudes from the one end (the end on the second end portion 92 side) of the outer inner peripheral surface 24 in a radial shape to the inner side in the radial direction, and has an annular shape as a whole. The annular groove 26 is a portion that is recessed radially outward from one end (end on the second end 92 side) of the annular convex portion 25, and has an annular shape as a whole. The inner inner peripheral surface 27 divides the annular groove 26 from one end (end on the second end portion 92 side) side, and extends to the second end portion 92 side, for example, with the same inner diameter as the annular convex portion 25. The stepped portion 28 is an annular portion that protrudes radially inward from one end (end on the second end portion 92 side) of the inner inner peripheral surface 27 over the entire circumference.

  The inner peripheral surface 23 is stepped at the second end 92 in order from the side closer to the second opening 22, the outer inner peripheral surface 34, the annular convex portion 35, the annular groove 36, the inner inner peripheral surface 37, and the step. 38. The outer inner circumferential surface 34 is a circumferential surface having the same inner diameter as the second opening 22, and extends continuously from the second opening 22 to the first end 91 side (left side in FIG. 2). The annular convex portion 35 is a portion protruding in a hook shape radially inward from one end (end on the first end portion 91 side) of the outer inner peripheral surface 34 and has an annular shape as a whole. The annular groove 36 is a portion that is recessed radially outward from one end (end on the first end 91 side) of the annular convex portion 35 and has an annular shape as a whole. The inner inner circumferential surface 37 extends toward the first end 91 with the same inner diameter as the annular convex portion 35, for example, while partitioning the annular groove 36 from one end (the end on the first end 91 side) side. The stepped portion 38 is an annular portion that protrudes radially inward from one end (end on the first end portion 91 side) of the inner inner peripheral surface 37 over the entire circumference.

  Further, a portion of the inner peripheral surface 23 sandwiched between the step 28 on the first end 91 side and the step 38 on the second end 92 side is a circumferential surface 39 having a substantially constant inner diameter. . A recess 40 that is recessed toward the radially outer side (upper side in FIG. 2) of the housing 9 is formed at a position that is biased toward the stepped side 38 on the circumferential surface 39. The recess 40 forms a part of the hollow portion 20 of the housing 9. A portion of the peripheral wall of the housing 9 that coincides with the recess 40 bulges outward in the radial direction according to the recess 40.

In the rack and pinion mechanism 10, the pinion 7 </ b> A of the pinion shaft 7 has a cylindrical shape or a columnar shape, and is connected so as to be coaxial with the pinion shaft 7. A plurality of gear teeth 41 are formed side by side in the circumferential direction on the outer peripheral surface of the pinion 7A. The pinion 7A is accommodated in the recess 40 described above.
The rack shaft 8 has a cylindrical shape extending in the axial direction X as described above. The rack shaft 8 is longer than the housing 9 in the axial direction X. Therefore, one end of the rack shaft 8 (left end in FIG. 2) protrudes from the first opening 21 to the outside of the housing 9 (left outer in FIG. 2), and the other end of the rack shaft 8 (right end in FIG. 2). Part) protrudes from the second opening 22 to the outside of the housing 9 (right outside in FIG. 2). The rack 8A described above is provided in a region that is biased toward the second opening 22 in the axial direction X at one place on the outer peripheral surface 8B of the rack shaft 8. The rack 8A is configured by a plurality of gear teeth 42 arranged in the axial direction X. The gear teeth 41 of the pinion 7A and the gear teeth 42 of the rack 8A mesh with each other. FIG. 2 shows the rack shaft 8 in a neutral state in which the wheels 15 (see FIG. 1) are not steered. At this time, the pinion 7A meshes with a central portion in the axial direction X of the rack 8A. The contents of FIGS. 3 and 4 will be described later.

Next, the first bush 11 will be described. FIG. 5 is a perspective view of the first bush 11. FIG. 6 is an exploded perspective view of the first bush 11.
With reference to FIGS. 5 and 6, the first bush 11 includes a bush main body 45 and a plurality of (here, two) O-rings 46.
The bush main body 45 is a resin hollow cylindrical shape, and the hollow portion is open on both sides in the axial direction. In the state where the first bush 11 is incorporated in the steering device 1 (see FIGS. 1 and 2), the axial direction of the bush body 45 coincides with the axial direction X described above. The inner diameter of the bush main body 45 is slightly larger than the outer diameter of the rack shaft 8, and the outer diameter of the bush main body 45 is somewhat smaller than the inner diameter of the inner inner peripheral surface 27 at the first end portion 91 of the housing 9 ( (See FIG. 2).

  Two insertion grooves 47 extending in the circumferential direction are formed on the outer peripheral surface 45A of the bush main body 45 at intervals in the axial direction. Each fitting groove 47 is formed over the entire circumferential direction of the outer peripheral surface 45 </ b> A of the bush body 45 and has an annular shape. The cross section of each fitting groove 47 when cut along a plane orthogonal to the circumferential direction of the bush main body 45 is a rectangular concave shape. The number of fitting grooves 47 and the number of O-rings 46 are the same, and here are two.

  At one end (the left end in FIGS. 5 and 6) in the axial direction of the bush body 45, a flange portion 48 that protrudes in a hook shape toward the radially outer side of the bush body 45 is integrally provided. The entire flange portion 48 is formed in an annular shape that is coaxial with the bush body 45. The outer diameter of the flange portion 48 is larger than the inner diameter of the annular convex portion 25 on the inner peripheral surface 23 of the housing 9 and smaller than the inner diameter of the annular groove 26 on the inner peripheral surface 23 (see FIG. 2).

  The bush body 45 is formed with a plurality of notches 49 extending in the axial direction of the bush body 45 and cutting the flange portion 48 and the bush body 45 from the flange portion 48 side. The notches 49 are arranged at a predetermined interval in the circumferential direction of the bush main body 45. Each notch 49 cuts the flange portion 48 in the radial direction and cuts a part of the peripheral wall of the bush main body 45 in the radial direction while traversing the two fitting grooves 47, so that the outer peripheral surface 45 </ b> A of the bush main body 45 is cut. And it is exposed from both sides of the inner peripheral surface 45B. The end of each notch 49 opposite to the flange 48 side (the right side in FIGS. 5 and 6) does not reach the edge of the bush body 45 on the opposite side.

  The O-ring 46 has an annular shape made of an elastic material such as rubber. The cross section of the O-ring 46 when cut along a plane perpendicular to the circumferential direction of the O-ring 46 has a circular shape. The two O-rings 46 are externally fitted to the bush main body 45, and in this state, any one O-ring 46 is fitted into each fitting groove 47. At this time, a certain amount of tension is applied to each O-ring 46.

  In the first bush 11 in the completed state as described above, as shown in FIG. 5, a part (radially outer portion) of each O-ring 46 extends from the fitting groove 47 (the outer peripheral surface 45 </ b> A of the bush main body 45). It protrudes radially outward. The first bush 11 can be elastically reduced in diameter by narrowing the width of each notch 49 (width in the circumferential direction). Therefore, when the first bush 11 is picked and a force is applied to the finger, the entire first bush 11 is reduced in diameter, and when the force is loosened, the first bush 11 is expanded to the original size.

  Next, the second bush 12 will be described. FIG. 7 is a perspective view of the second bush 12 according to the first embodiment. FIG. 8 is an exploded perspective view of the second bush 12 according to the first embodiment. FIG. 9A is a perspective view of the bush main body 55 with respect to the second bush 12 according to the first embodiment, as viewed from a direction different from FIG. 8, and FIG. 9B is a view from the outside in the radial direction. 9 (c) is a side view of the bush main body 55 as viewed from the outside in the axial direction, and FIG. 9 (d) is taken along the line AA in FIG. 9 (b). It is sectional drawing. Here, the 2nd bush 12 has 1st Embodiment shown in FIGS. 7-9, 2nd Embodiment (refer FIG. 13) mentioned later, and 3rd Embodiment (refer FIGS. 14-16). . The details differ in each of the second bushes 12 of the first embodiment, the second embodiment, and the third embodiment.

7 and 8, the second bush 12 includes a bush main body 55 and an O-ring 56 (elastic member).
The bush main body 55 is made of resin and forms an outer shell of the second bush 12. The bush main body 55 forms a C-shaped arc whose center of curvature is the reference line Y indicated by a two-dot chain line in FIG. The direction in which the reference line Y extends is the axial direction of the bush main body 55, and when viewed from the axial direction as “side view”, the bush main body 55 is C-type in side view. The bush main body 55 has a predetermined width in the axial direction. In other words, the bush main body 55 has the same shape as that obtained by cutting one place on the circumference of a cylinder having a central axis extending in the axial direction. The entire second bush 12 including such a bush body 55 is also C-shaped in a side view. In the state where the second bush 12 is incorporated in the steering device 1 (see FIGS. 1 and 2), the axial direction of the bush body 55 coincides with the axial direction X described above.

  In the bush main body 55, the outer side surface in the radial direction centered on the reference line Y is referred to as an outer peripheral surface 55A, and the inner side surface in the radial direction is referred to as an inner peripheral surface 55B. Both the outer peripheral surface 55A and the inner peripheral surface 55B are side-view C-type. Further, in the bush main body 55, when the portion that is interrupted in the C-shaped circumferential direction is an open portion 55C, the inner peripheral surface 55B side of the bush main body 55 is on both sides in the axial direction and on the open portion 55C side (perpendicular to the axial direction). Side).

The inner diameter (in the inner peripheral surface 55B) of the bush main body 55 is slightly larger than the outer diameter of the rack shaft 8, and the outer diameter (in the outer peripheral surface 55A) of the bush main body 55 is the inner side at the second end 92 of the housing 9. It is somewhat smaller than the inner diameter of the inner peripheral surface 37 (see FIG. 2).
Two fitting grooves 57 extending in the circumferential direction are formed on the outer circumferential surface 55 </ b> A of the bush main body 55 at intervals in the axial direction. The two fitting grooves 57 extend in parallel along the circumferential direction. Each fitting groove 57 is formed over the entire circumferential direction of the outer peripheral surface 55 </ b> A of the bush main body 55, and has a C shape in a side view like the bush main body 55. The cross section of each fitting groove 57 when cut along a plane perpendicular to the circumferential direction of the bush body 55 is a rectangular concave shape.

  On the outer peripheral surface 55A, when each fitting groove 57 is regarded as a concave portion, a portion other than the concave portion is a convex portion 58 (see FIG. 9B). The convex portions 58 are streaks extending in the circumferential direction, and three convex portions 58 are provided so as to be alternately arranged with the two fitting grooves 57 in the axial direction. Each convex portion 58 extends over substantially the entire region in the circumferential direction of the outer peripheral surface 55A. Of the three convex portions 58, each of both circumferential ends of the convex portion 58 located in the middle in the axial direction forms a locking portion 59. In FIG. 8, of the pair of locking portions 59, the locking portion 59 at a position that cannot be seen in FIG. 8 is indicated by a virtual line (dotted line). The pair of locking portions 59 are located on both end sides in the circumferential direction of each fitting groove 57. Each locking portion 59 has a block shape that bulges in an arc shape toward the open portion 55C side of the bush main body 55 when viewed from the outside in the radial direction.

  One end of the bush main body 55 in the axial direction (the end on the right front side in FIGS. 8 and 9B) is integrally provided with a flange portion 60 (positioning portion) projecting in a hook shape toward the radially outer side of the bush main body 55. Provided. The entire flange portion 60 is formed in a C shape in a side view that is coaxial with the bush body 55. In the radial direction, the flange portion 60 projects outward from the outer peripheral surface 55A (including the tip of the convex portion 58) of the bush main body 55 (see FIG. 9B). The outer diameter of the flange portion 60 is larger than the inner diameter of the annular convex portion 35 on the inner peripheral surface 23 of the housing 9 and smaller than the inner diameter of the annular groove 36 on the inner peripheral surface 23 (see FIG. 2). In addition, on the outer peripheral surface of the flange portion 60, a protrusion 62 that bulges out in an arc shape in a side view in the radial direction is integrally provided at a substantially center in the circumferential direction.

  The bush main body 55 is formed with a plurality of (here, four) notches 61 that extend in the axial direction of the bush main body 55 and cut the flange portion 60 and the bush main body 55 from the flange portion 60 side. These notches 61 are arranged at a predetermined interval in the circumferential direction of the bush main body 55. Each notch 61 cuts the flange portion 60 in the radial direction and cuts a part of the peripheral wall of the bush main body 55 in the radial direction while traversing the two fitting grooves 57, so that the outer peripheral surface 55 </ b> A of the bush main body 55 is cut. And it is exposed from both sides of the inner peripheral surface 55B. The end of each notch 61 opposite to the flange 60 side (the left side in FIGS. 8 and 9B) does not reach the edge of the bush body 55 on the opposite side. It extends to just before the opposite convex portion 58 (see FIG. 9B). Since the notch 61 is formed, the two convex portions 58 other than the opposite convex portion 58 are interrupted in the circumferential direction.

  The O-ring 56 is an annular shape made of an elastic material such as rubber. The cross section of the O-ring 56 when cut along a plane orthogonal to the circumferential direction of the O-ring 56 has a circular shape. In the second bush 12, only one O-ring 56 is provided. One O-ring 56 is bent so as to be flat in the axial direction of the bush body 55 as shown in FIG. It is locked to the pair of locking portions 59 (see FIG. 7 and FIG. 9D). Further, in the O-ring 56, a portion extending in the circumferential direction on the flange portion 60 side relative to the locking portion 59 is fitted in the fitting groove 57 on the flange portion 60 side, and the remaining portion (more than the locking portion 59). The portion extending in the circumferential direction on the opposite side to the flange portion 60 side) is fitted into the remaining (opposite side) fitting groove 57 (see FIGS. 7 and 9B). That is, the single O-ring 56 is fitted into both the fitting grooves 57 while being locked to the locking portions 59 at both ends in the circumferential direction of the fitting groove 57. At this time, a certain amount of tension is applied to the O-ring 56.

Note that the portions of the O-ring 56 that are locked to the pair of locking portions 59 are not circular in cross-section so as to be securely locked to the locking portions 59. You may have a thin film-like cross section which can carry out surface contact with the surface. Moreover, it is preferable that each latching | locking part 59 is a shape (for example, hook shape) which can latch the O-ring 56 reliably.
In the second bush 12 in the completed state as described above, as shown in FIG. 7, a part of the O-ring 56 (radially outer portion) extends from each fitting groove 57 (the outer peripheral surface 55 </ b> A of the bush main body 55). It protrudes radially outward (see also FIG. 9 (b) and FIG. 9 (d)). The second bush 12 can be elastically reduced in diameter in the same manner as the first bush 11 by narrowing the width of each notch 61 (width in the circumferential direction). Therefore, when the second bush 12 is picked and a force is applied to the finger, the entire diameter of the second bush 12 is reduced, and when the force is loosened, the diameter of the second bush 12 is expanded to the original size.

Next, assembly of the rack and pinion mechanism 10, the first bush 11, and the second bush 12 to the housing 9 will be described.
FIG. 10A is a cross-sectional view of the housing 9 and shows a state immediately after the first bush 11 is assembled. FIG. 10B shows the housing 9 of FIG. It is a perspective view which shows a mode that the 2nd bush 12 is assembled | attached. FIG. 11 (a) shows a state immediately after the second bush 12 is assembled to the housing 9 in FIG. 10 (a), and FIG. 11 (b) is a cross-sectional view taken along line BB in FIG. 11 (a). It is sectional drawing in a line. FIG. 12 shows a state immediately after the rack shaft 8 is assembled to the housing 9 in FIG.

  First, referring to FIG. 10A, the first bush 11 is assembled to the housing 9. Specifically, the first bush 11 in the state before the diameter reduction is inserted into the first opening 21 of the housing 9 along the axial direction X. At this time, in the first bush 11, a portion excluding the flange portion 48 in the bush main body 45 passes through the first opening 21 before the flange portion 48. Thereafter, the portion of the bush body 45 of the first bush 11 excluding the flange portion 48 passes through the portion surrounded by the annular convex portion 25 and the portion surrounded by the annular groove 26 in this order, It is inserted inside the surface 27. At this time, in the first bush 11, the O-ring 46 contacts the inner inner peripheral surface 27 from the inner side in the radial direction to the entire periphery, and is compressed to some extent between the inner inner peripheral surface 27 and the bush body 45. However, a certain amount of clearance (radial clearance) is ensured over the entire circumference between the inner inner peripheral surface 27 and the outer peripheral surface 45A of the bush main body 45.

  Then, when the portion excluding the flange portion 48 in the bush main body 45 is continuously inserted into the inside of the inner inner peripheral surface 27, the flange portion 48 comes into contact with the annular convex portion 25 from the first opening 21 side, and no more than the first bush. 11 can not advance. Therefore, as described above, when the first bush 11 (especially the flange portion 48) is picked and reduced in diameter, the outer diameter of the flange portion 48 becomes smaller than the inner diameter of the annular convex portion 25 on the inner peripheral surface 23 of the housing 9. Therefore, the flange portion 48 (that is, the entire first bush 11) can pass through the portion surrounded by the annular convex portion 25. When the diameter of the first bush 11 is increased to the original size after the flange portion 48 has passed through the portion surrounded by the annular convex portion 25, the flange portion 48 is radial with respect to the annular groove 26 over the entire circumference. Fit from inside.

  Thereby, as shown in FIG. 10A, the first bush 11 is positioned in the axial direction X at the flange portion 48, and the assembly of the first bush 11 to the housing 9 is completed. In this state, the outer peripheral surface 45 </ b> A of the bush main body 45 faces the inner inner peripheral surface 27 from the radially inner side. Each of the two O-rings 46 is compressed to some extent between the inner inner peripheral surface 27 and the bush main body 45, but between the inner inner peripheral surface 27 and the outer peripheral surface 45A of the bush main body 45, A certain amount of clearance is secured over the entire circumference. As described above, the first bush 11 is set at the end portion (first end portion 91) immediately adjacent to the first opening 21 in the housing 9, so that it can be easily assembled to the housing 9.

In addition to the fact that the flange portion 48 is fitted in the annular groove 26, the step 28 of the housing 9 is located at the tip of the bush body 45, so that the first bush 11 is stepped in the hollow portion 20 of the housing 9. There is no deviation beyond the attachment 28 toward the second end 92.
Next, as shown in FIG. 10B, the second bush 12 is assembled to the housing 9. Specifically, the second bushing 12 in a state before the diameter reduction is inserted into the second opening 22 of the housing 9 along the axial direction X (see the thick arrow in FIG. 10B). At this time, in the second bush 12, a portion of the bush main body 55 excluding the flange portion 60 passes through the second opening 22 before the flange portion 60. After that, the portion of the bush body 55 of the second bush 12 excluding the flange portion 60 was surrounded by the portion surrounded by the annular protrusion 35 and the annular groove 36 (the portion painted black in FIG. 10B). The portions pass through in this order and are inserted inside the inner inner peripheral surface 37.

  At this time, in the second bush 12, a portion fitted in the fitting groove 57 in one O-ring 56 comes into contact with the inner inner peripheral surface 37 from the radially inner side. However, since the second bush 12 is C-shaped in a side view as described above, the second bush 12 can freely move to some extent in the radial direction of the housing 9 (hollow portion 20) in the cylindrical hollow portion 20 of the housing 9. Therefore, even when the O-ring 56 comes into contact with the inner inner peripheral surface 37 when the bush main body 55 is inserted into the inner inner peripheral surface 37, the contact is almost resistant to the insertion of the bush main body 55. Absent.

  That is, in the second bush 12 having the C-shaped bush body 55 in the side view, the housing 9 has the second bush body 55 as compared with the case where the bush body 55 has a cylindrical shape (O-type in the side view, see the first bush 11). When the two bushes 12 are assembled, the portion that becomes the resistance in the second bush 12 is reduced. The said part is a part compressed in the O ring 56 between the bush main body 55 of the 2nd bush 12, and the inner peripheral surface 23 (inner inner peripheral surface 37) of the housing 9. FIG. Therefore, the second bush 12 can be easily and smoothly assembled to the housing 9. As a result, the assembling property of the second bush 12 can be improved.

  Then, when the portion excluding the flange portion 60 in the bush main body 55 is continuously inserted into the inside of the inner inner peripheral surface 37, the flange portion 60 comes into contact with the annular convex portion 35 from the second opening 22 side, and the second bush is further increased. 12 can not advance. Therefore, as described above, when the second bush 12 (particularly the flange portion 60) is picked and reduced in diameter, the outer diameter of the flange portion 60 becomes smaller than the inner diameter of the annular convex portion 35 on the inner peripheral surface 23 of the housing 9. Therefore, the flange portion 60 (that is, the second bush 12 as a whole) can pass through the portion surrounded by the annular convex portion 35. When the diameter of the second bush 12 is increased to the original size after the flange portion 60 has passed through the portion surrounded by the annular convex portion 35, the flange portion 60 is moved all around as shown in FIG. It fits into the annular groove 36 from the inner side in the radial direction, and thereby engages with the housing 9.

Then, by engaging the flange portion 60 with the housing 9, the second bush 12 is positioned with respect to the housing 9 in the flange portion 60 (in the axial direction X), and the assembly of the second bush 12 to the housing 9 is completed. To do.
As described above, in the second bushing 12 having the C-shaped bushing body 55 in side view, the second bushing 12 is assembled to the housing 9 as compared with the case where the bushing body 55 is cylindrical (in the case of the first bushing 11). In this case, the posture of the second bush 12 can be changed relatively freely in the housing 9. Accordingly, the flange portion 60 provided on the bush main body 55 can be successfully engaged with the annular groove 36 of the housing 9. Thereby, a member for positioning the second bush 12 is provided separately from the second bush 12, and the second bush 12 is not positioned with the member after the second bush 12 is set in the housing 9. Since the second bush 12 can be positioned in the housing 9, the number of parts can be reduced. Further, as described above, the second bush 12 is set at the end portion (second end portion 92) immediately adjacent to the second opening 22 in the housing 9, so that it can be easily assembled to the housing 9.

In addition, since the stepped portion 38 of the housing 9 is located at the tip of the bush body 55 except that the flange portion 60 is fitted in the annular groove 36, the second bush 12 is stepped in the hollow portion 20 of the housing 9. There is no deviation beyond the attachment 38 toward the first end 91 side.
Thus, in the state where the assembly of the second bush 12 to the housing 9 is completed, the outer peripheral surface 55A of the bush main body 55 faces the inner inner peripheral surface 37 from the radially inner side. In this state, the O-ring 56 is in contact with the inner inner circumferential surface 37 from the radially inner side. However, as described above, since the second bush 12 can freely move to some extent in the radial direction in the housing 9 (hollow portion 20), the O-ring 56 is almost compressed between the inner inner peripheral surface 37 and the bush main body 55. It has not been. Therefore, the outer peripheral surface 55A of the bush body 55 is in a state of floating radially inward from the inner inner peripheral surface 37, and between the outer peripheral surface 55A and the inner inner peripheral surface 37, over the entire circumference, A certain amount of gap is secured.

  Here, as shown in FIG. 11 (b), in the annular groove 36 of the housing 9, the portion that coincides with the protrusion 62 on the outer peripheral surface of the flange portion 60 is deeper than the annular groove 36 continuously from the annular groove 36. A recessed locking groove 36A is formed. The protrusion 62 of the flange portion 60 is fitted into the locking groove 36A from the inside in the radial direction. Thereby, the 2nd bush 12 whole is positioned in the circumferential direction, and does not rotate. The second bush 12 can be positioned in the circumferential direction even if the protrusion 62 is provided in the locking groove 36A (the inner peripheral surface 23 of the housing 9) and the locking groove 36A is provided on the outer peripheral surface of the flange portion 60.

  As shown in FIG. 11B, the second bush 12 positioned in the circumferential direction as seen from the axial direction X has an open portion 55C in the recess 40 of the housing 9 (see FIG. 11A). It is arranged along a position (position farthest from the depression 40) that is shifted 180 ° from the depression 40 in the circumferential direction on the inner peripheral surface 23 of the housing 9 so as to face the reference) side. Therefore, when viewed from the axial direction X, in the bush main body 55, not the outer peripheral surface 55A but the inner peripheral surface 55B is located on the depression 40 side.

In FIG. 11B, for convenience of explanation, illustration of the O-ring 56 (see FIG. 11A) is omitted, while the rack shaft 8 is indicated by a dotted line.
Next, referring to FIG. 12, the rack shaft 8 is inserted into the housing 9 (hollow portion 20) from the first opening 21 or the second opening 22. When the rack shaft 8 is inserted into the housing 9 from the first opening 21, the rack shaft 8 extends along the axial direction X in the hollow portion of the bush body 45 of the first bush 11 and the circumferential surface 39 of the housing 9. And it inserts in this order with respect to the internal peripheral surface 55B side of the bush main body 55 of the 2nd bush 12. As shown in FIG.

Conversely, when the rack shaft 8 is inserted into the housing 9 from the second opening 22, the rack shaft 8 extends along the axial direction X on the inner peripheral surface 55 </ b> B side of the bush body 55 of the second bush 12. 9 and the hollow surface of the bush body 45 of the first bush 11 are inserted in this order.
In any case, when the rack shaft 8 is inserted into the hollow portion of the bush body 45 of the first bush 11, the first bush 11 is fitted to the rack shaft 8 from the radially outer side at the first end portion 91. In this state, it is arranged between the rack shaft 8 and the inner peripheral surface 23 of the housing 9. When the rack shaft 8 is inserted into the inner peripheral surface 55B side of the bush main body 55 of the second bush 12, the second bush 12 is connected to the rack shaft 8 at the second end portion 92 (one end of the housing 9). On the other hand, it is fitted from the outside in the radial direction and is disposed between the rack shaft 8 and the inner peripheral surface 23 of the housing 9.

  A chamfered portion 63 is provided at each end edge in the axial direction X of each of the inner peripheral surface 45B of the bush main body 45 of the first bush 11 and the inner peripheral surface 55B of the bush main body 55 of the second bush 12. (See FIGS. 5 and 7). Therefore, the rack shaft 8 can be smoothly inserted into the hollow portion of the bush body 45 of the first bush 11 and the inner peripheral surface 55B side of the bush body 55 of the second bush 12 without being caught.

  Here, the second bush 12 was able to move freely to some extent in the radial direction in the housing 9 before the rack shaft 8 was inserted (see FIG. 11), but in the state where the rack shaft 8 was inserted. The inner wall 37 is pressed by the rack shaft 8 and cannot move freely in the radial direction in the housing 9 alone. The second bush 12 at this time is pressed by the rack shaft 8 in a direction away from the recess 40 when viewed from the axial direction X (downward in FIG. 12). Then, the second bush 12 is pressed against the inner inner peripheral surface 37 side by the rack shaft 8 in this way, so that in the second bush 12, the O-ring 56 is connected to the bush main body 55 and the inner inner peripheral surface 37 (housing 9). It is sandwiched between and compressed. However, a certain amount of clearance is ensured between the outer peripheral surface 55A of the bush body 55 and the inner inner peripheral surface 37 over the entire circumference.

  Then, as shown in FIG. 12, the end of the rack shaft 8 that is first inserted into one of the first opening 21 and the second opening 22 protrudes from the other of the first opening 21 and the second opening 22. Then, the insertion of the rack shaft 8 into the housing 9 (assembly of the rack shaft 8 with respect to the housing 9) is completed. The rack shaft 8 that has been assembled is not in contact with the housing 9 in any part.

  Here, on the outer peripheral surface 8B of the rack shaft 8, one portion in the axial direction X of the region on the recess 40 side (upper side in FIG. 12) of the housing 9 (in FIG. 12, adjacent to the rack 8A from the first end 91 side). The position is formed with a recess 100 (not shown in other drawings) that is recessed toward the center of the rack shaft 8. When the rack shaft 8 is being assembled to the housing 9 (when the rack shaft 8 is being inserted), the insertion of the rack shaft 8 is temporarily stopped in a state where the recess 100 and the recess 40 coincide with each other in the axial direction X. . At this time, since the recess 100 and the recess 40 are combined to form a relatively large space, the pinion 7A (see FIG. 2) of the pinion shaft 7 is inserted into this space, and then the rack shaft 8 is inserted. Resume. Then, since the hollow part 100 is separated from the hollow 40 in the axial direction X, the pinion 7A in the hollow 40 is removed from the hollow part 100 accordingly, and the gear teeth 41 of the pinion 7A and the rack shaft are removed as shown in FIG. The gear teeth 42 of the eight racks 8A are brought into mesh with each other.

  Immediately before the gear teeth 41 and the gear teeth 42 start to mesh with each other, the pinion 7A momentarily rides on the rack 8A (the end on the recess 100 side), so that the rack shaft 8 moves away from the recess 40 (the second bush 12 side). ) Slightly bent. At this time, the rack shaft 8 is slightly displaced in the radial direction so that the O-ring 56 of the second bush 12 is compressed between the bush body 55 and the inner peripheral surface 23 (inner inner peripheral surface 37) of the housing 9. That's right. Thereafter, when the gear teeth 41 and the gear teeth 42 are properly engaged with each other, the rack shaft 8 quickly returns to a state before being bent (position before being shifted in the radial direction). When the insertion of the rack shaft 8 into the housing 9 is completed (see also FIG. 12), the assembly of the rack shaft 8 to the housing 9 is completed, the rack and pinion mechanism 10 is completed, and the rack to the housing 9 is further completed. The assembly of the and pinion mechanism 10 is also completed. The insertion direction of the rack shaft 8 here is a direction from the second opening 22 toward the first opening 21 (a leftward direction) for convenience of the position of the recess 100 (see FIG. 12).

Next, the roles of the first bush 11 and the second bush 12 in the steering device 1 will be described.
As described above with reference to FIGS. 2 and 3, both the first bush 11 and the second bush 12 are fitted to the rack shaft 8 from the outside in the radial direction. Therefore, in the first bush 11, the inner peripheral surface 45B of the bush main body 45 is in surface contact with the outer peripheral surface 8B of the rack shaft 8, and in the second bush 12, the inner peripheral surface 55B of the bush main body 55 is The rack shaft 8 is in surface contact with the outer peripheral surface 8B. As a result, the first bush 11 and the second bush 12 support the rack shaft 8 so as to be slidable in the axial direction X. Here, since the first bush 11 is positioned on the housing 9 at the flange portion 48 and the second bush 12 is positioned on the housing 9 at the flange portion 60, the rack shaft 8 is moved along with the operation of the steering member 2. Even if it slides in the axial direction X, the position in the axial direction X of these bushes does not shift.

  In the first bush 11, two O-rings 46 attached to the bush main body 45 are compressed by the bush main body 45 and the inner inner peripheral surface 27 of the housing 9. In the second bush 12, the bush main body 45 is compressed. One O-ring 56 attached to 55 is compressed to the bush body 55 and the inner inner peripheral surface 37 of the housing 9. Thus, the first bush 11 and the second bush 12 elastically support the rack shaft 8 in the radial direction. Further, the first bush 11 (see FIG. 5) having the notch 49 and the second bush 12 having the notch 61 (FIG. 7) due to the elastic contraction force acting radially inward in each O-ring 46 and O-ring 56. The diameter is slightly reduced. Thereby, the inner peripheral surface 45B of the bush main body 45 of the first bush 11 and the inner peripheral surface 55B of the bush main body 55 of the second bush 12 are in surface contact with the outer peripheral surface 8B of the rack shaft 8 without a gap. .

  Here, when the vehicle is traveling, when the radial load (radial load) applied from the rack shaft 8 to the first bush 11 and the second bush 12 is small (when the steering member 2 is not operated). In other words, the radially outer portion of each O-ring 46 protrudes from the outer peripheral surface 45 </ b> A of the bush main body 45 of the first bush 11 and contacts the inner inner peripheral surface 27 of the housing 9. Further, the radially outer portion of the O-ring 56 protrudes from the outer peripheral surface 55 </ b> A of the bush main body 55 of the second bush 12 and is in contact with the inner inner peripheral surface 37 of the housing 9. As a result, the low load described above is absorbed by the O-rings 46 and 56, and the radial gap S between the outer peripheral surface 45 </ b> A of the bush main body 45 of the first bush 11 and the inner inner peripheral surface 27 of the housing 9. Is ensured over the entire circumferential direction (see FIG. 3A). Further, a gap S in the radial direction is also secured across the entire circumferential direction between the outer peripheral surface 55A of the bushing body 55 of the second bush 12 and the inner inner peripheral surface 37 of the housing 9 (FIG. 3B). )reference).

  Therefore, when the radial load is small, the bush body 45 of the first bush 11 is elastically supported by the two O-rings 46 so as to float inward from the inner inner peripheral surface 27 of the housing 9 in the radial direction. Has been. At this time, the bushing body 55 of the second bushing 12 is elastically supported by one O-ring 56 so as to float inward from the inner inner peripheral surface 37 of the housing 9 in the radial direction. Thereby, since the rack shaft 8 supported by the first bush 11 and the second bush 12 is also elastically supported, it is possible to prevent the rack shaft 8 from rattling.

  On the other hand, the radial load from the rack shaft 8 to the first bush 11 may increase due to operation of the steering member 2 during traveling or the wheels 15 (see FIG. 1) hitting the curb. At such a high load, as shown in FIG. 4A, the first bush 11 compresses the two O-rings 46 while the bush body 45 compresses the two O-rings 46 in the radial direction (the lower side in FIG. 4A). ). Finally, each O-ring 46 is completely accommodated in the fitting groove 47, and the outer peripheral surface 45A of the bush body 45 of the first bush 11 contacts the inner inner peripheral surface 27 of the housing 9, The above-described gap S (see FIG. 3A) disappears at one place on the circumference.

  Further, when the radial load from the rack shaft 8 to the second bush 12 is increased, in the second bush 12, the bush body 55 compresses one O-ring 56 in the radial direction as shown in FIG. It moves to the outer side (lower side in FIG.4 (b)). Finally, the O-ring 56 is completely accommodated in each fitting groove 57, and the outer peripheral surface 55A of the bush body 55 of the second bush 12 contacts the inner inner peripheral surface 37 of the housing 9, The above-described gap S (see FIG. 3B) disappears over the entire circumferential direction.

  That is, when the load is high, resin portions such as the bush body 45 of the first bush 11 and the bush body 55 of the second bush 12 directly contact the inner peripheral surface 23 (the inner inner peripheral surface 27 and the inner inner peripheral surface 37) of the housing 9. By absorbing high load. As a result, the first bush 11 and the second bush 12 can no longer be displaced outward in the radial direction, so that the rack shaft 8 is prevented from being bent in the radial direction. The rigidity can be maintained.

When the first bush 11 and the second bush 12 cannot be displaced radially outward in this way, the O-ring 46 and the O-ring 56 are fully compressed, and the cross section of each O-ring is initially It is elastically deformed from a true circular shape (see FIGS. 3A and 3B) to an elliptical shape (see FIGS. 4A and 4B).
Referring to FIG. 2, second bush 12 removes backlash of the meshing portions (gear teeth 41 and 42) of rack 8A and pinion 7A in addition to the function of supporting rack shaft 8 as described above. It also has a function. Specifically, as described above, the second bush 12 has a C-type in a side view, and is disposed on the inner peripheral surface 23 of the housing 9 at a position farthest from the pinion shaft 7 of the recess 40. In the second bush 12, an O-ring 56 is attached to the outer peripheral surface 55 </ b> A of the bush main body 55 (the side surface farthest from the pinion shaft 7 in the bush main body 55), and the bush main body 55 and the inner peripheral surface 23 of the housing 9. It is sandwiched and compressed. Thereby, the O-ring 56 elastically urges the rack shaft 8 toward the pinion shaft 7 via the bush main body 55 by its own elastic force.

  In this case, in the axial direction X, the second bush 12 is located away from the meshing portion between the rack shaft 8 and the pinion shaft 7 toward the second end portion 92. Therefore, the second bush 12 has itself as a power point, another bush (first bush 11) as a fulcrum, and the meshing portion of the rack shaft 8 and the pinion shaft 7 as a point of action between the force point and the fulcrum. By the “lever principle”, the rack shaft 8 can be biased toward the pinion shaft 7 sufficiently and sufficiently. In order to forcefully bias the rack shaft 8 toward the pinion shaft 7, the second bush 12 is thus separated as much as possible in the axial direction X from the meshing portion of the rack shaft 8 and the pinion shaft 7, and the power point It is desirable to increase the distance between the point and the action point.

Further, in the second bush 12, one O-ring 56 is fitted in two fitting grooves 57 (see FIGS. 7 and 8). As a result, the rack shaft 8 can be urged sufficiently and sufficiently toward the pinion shaft 7 by the urging force when there are only two O-rings 56 even though there is only one O-ring 56. The number of parts can be reduced.
On the other hand, the rack shaft 8 is directed to the pinion shaft 7 by the first bush 11 having the O-shaped (cylindrical) bush body 45 in the side view, not the second bush 12 having the C-type bush body 55 in the side view. It is also possible to energize. However, in that case, the first bush 11 is arranged eccentrically with respect to the rack shaft 8 so that the first bush 11 presses the rack shaft 8 from one place on the circumference, or the shape of the inner inner peripheral surface 27 is changed. The configuration for that must be complicated. However, in the second bush 12, the rack shaft 8 is connected to the pinion shaft 7 only by a simple and inexpensive configuration in which the bush main body 55 is C-shaped in a side view and an elastic member such as an O-ring 56 is attached to the outer peripheral surface 55 A of the bush main body 55. Can be energized towards.

Next, the 2nd bush 12 of 2nd Embodiment and 3rd Embodiment is demonstrated.
In the second bushing 12 of the first embodiment described so far with reference to FIG. 8, a plurality of (here, four) notches 61 extend in the axial direction of the bushing body 55 to the flange portion 60 side. The flange portion 60 and the bush main body 55 are cut from each other, and the two fitting grooves 57 are crossed (see FIG. 9B). Therefore, a corner 70 that intersects each notch 61 in each fitting groove 57 is inevitably formed on the outer peripheral surface 55A of the bush body 55 (specifically, a bottom surface 57A that extends in the circumferential direction in each fitting groove 57). Has been.

  The corner portion 70 is a connecting portion between the bottom surface 57A of each fitting groove 57 and a section screen 55D that extends in the axial direction and the radial direction in the bush body 55 to partition each notch 61 (see FIG. 9D). ). In the second bush 12 of the first embodiment, each corner 70 is inevitably pointed, and the angle α of the corner 70 when cut along a plane orthogonal to the axial direction becomes an acute angle of about 90 °. (See FIG. 9 (d)). Here, the O-ring 56 fitted in the fitting groove 57 is pressed against the bottom surface 57A by attempting to reduce the diameter by its urging force. Therefore, each corner 70 of the bottom surface 57A bites into the O-ring 56, and stress concentrates on the contact portion of the O-ring 56 with the corner 70, so that the O-ring 56 breaks at the contact portion. It is assumed that If the O-ring 56 breaks, the O-ring 56 cannot sufficiently urge the rack shaft 8 against the pinion shaft 7, thereby increasing the backlash described above, and noise is generated. Or the operation feeling of the steering member 2 (see FIG. 1) may be reduced.

  Therefore, in the second bush 12 of the present invention, the O-ring 56 caused by the corner portion 70 is prevented from being broken by the configurations of the following second and third embodiments. In the second bushing 12 of the second embodiment and the third embodiment, the same parts as those described in the second bushing 12 of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. . The first embodiment, the second embodiment, and the third embodiment are the same except for the configuration that prevents the O-ring 56 from being broken. In the second embodiment and the third embodiment, the bush main body 55 is seen in a side view C. Since it is a type | mold, the 2nd bush 12 can be assembled | attached with respect to the housing 9 easily and smoothly.

FIG. 13A is a perspective view of the bush body 55 of the second bush 12 according to the second embodiment, and FIG. 13B is a side view of the bush body 55 as viewed from the outside in the radial direction. 13 (c) is a cross-sectional view taken along line CC of FIG. 13 (b).
First, in the second embodiment shown in FIG. 13, each corner 70 is chamfered in the bush main body 55. That is, in each corner portion 70 of the second embodiment, a chamfered portion 71 is formed at a portion (see FIG. 8) sharpened in the first embodiment described above (see FIG. 13C). Note that the chamfered portion 71 here includes, in addition to the so-called C surface, an R surface obtained by rounding the above-described sharp portion.

  If each corner 70 is chamfered in this way, the corner 70 bites into the O-ring 56 fitted in each fitting groove 57 (stress concentration at the contact portion of the O-ring 56 with the corner 70). ), It is possible to prevent the O-ring 56 from being broken and to improve the durability of the O-ring 56. On the other hand, since the notch 61 is present, the second bush 12 can be easily assembled to the housing 9 by reducing the diameter (see FIG. 10B).

  FIG. 14 is a perspective view of the second bush 12 according to the third embodiment. FIG. 15 is an exploded perspective view of the second bush 12 according to the third embodiment. FIG. 16A is a perspective view of the bush body 55 with respect to the second bush 12 according to the third embodiment, as viewed from a direction different from that of FIG. 15, and FIG. 16 (c) is a side view of the bush main body 55 as viewed from the outside in the axial direction, and FIG. 16 (d) is a sectional view taken along the line DD in FIG. 16 (b). It is sectional drawing.

  And in the 2nd bush 12 of 3rd Embodiment shown in FIGS. 14-16, the notch 61 (refer FIG. 8 and FIG. 13) mentioned above in the bush main body 55 is not formed. Here, in the third embodiment, the fitting groove 57 into which the O-ring 56 described above is fitted is referred to as a first groove 57. A first groove 57 (extending in the circumferential direction) and a second groove 72 extending in the axial direction are formed on the outer peripheral surface 55A of the bush main body 55 of the third embodiment. The second grooves 72 are provided at a plurality of positions (for example, four positions on the circumference that coincide with the notches 61 described above) at a predetermined interval in the circumferential direction of the bush main body 55.

  The second groove 72 is located at the same position on the outer peripheral surface 55A of the bush main body 55 at a position avoiding the first grooves 57, that is, on the outer peripheral surfaces of the flange portion 60 and the three convex portions 58, respectively. Is formed. That is, in the same place, the second groove 72 is formed in a total of four places such as the outer peripheral surfaces of the flange portion 60 and the three convex portions 58. The second groove 72 is provided over the entire region in the axial direction in the flange portion 60 and each convex portion 58, but unlike the notch 61 (see FIG. 8), it penetrates the peripheral wall of the bush body 55 in the radial direction. It is not exposed from the inner peripheral surface 55B of the bush body 55. The second groove 72 is not provided on the bottom surface 57 </ b> A of the first groove 57. As shown in FIG. 15, the bottom surface 72A of the second groove 72 may be flush with the bottom surface 57A of the first groove 57, or may be on the inner side in the radial direction than the bottom surface 57A. May be. In short, the second groove 72 may be provided at a position avoiding the first groove 57 on the outer peripheral surface 55A of the bush body 55.

  A third groove 73 is formed at a position that coincides with each second groove 72 in the circumferential direction on the inner peripheral surface 55B of the bush main body 55 (see FIG. 16C). Since the second groove 72 is provided at four positions in the circumferential direction (circumferential), the third groove 73 is also provided at four positions in the circumferential direction (position on the back side of each second groove 72). It has been. Each of the third grooves 73 extends in the axial direction while being recessed toward the second groove 72 (radially outward) at the same position in the circumferential direction, and is provided over the entire area in the axial direction on the inner peripheral surface 55B. (See FIG. 16 (a)). Thus, since the second groove 72 is provided on the outer peripheral surface 55A and the third groove 73 is provided on the inner peripheral surface 55B at the same position in the circumferential direction of the bush main body 55, the thickness of the bush main body 55 is increased. (Dimension in the radial direction) is smaller at the position than at the position (see FIG. 16D).

  Therefore, even if the second groove 72 is not a notch penetrating the peripheral wall of the bush main body 55 (see the notch 61 in FIG. 8), the second bush 12 is easily bent, and the first embodiment described above ( The diameter can be reduced to the same extent as in the case of FIG. 7) and the second embodiment (see FIG. 13). Therefore, the second bush 12 can be easily and smoothly assembled to the housing 9 (see FIG. 10B). Thereby, the further improvement of the assembly | attachment property of a bush can be aimed at.

  In the 2nd bush 12 of such 3rd Embodiment, the corner | angular part 70 itself (refer FIGS. 7-9 and FIG. 13) does not exist. That is, the first groove 57 into which the O-ring 56 is fitted does not have a portion that causes stress concentration in the O-ring 56. Therefore, in the case of the third embodiment, stress concentration does not occur in the O-ring 56 than in the case of the first embodiment or the second embodiment. The durability can be further improved. As described above, even if the notch 61 is not provided, the second bush 12 can be reduced in diameter and easily assembled to the housing 9.

  As described above, because the O-ring 56 is pressed against the bottom surface 57A of each fitting groove (first groove) 57, the breakage of the O-ring 56 is caused by contact between the O-ring 56 and each corner 70 of the bottom surface 57A. Therefore, the breakage of the O-ring 56 can be reliably prevented by the second and third embodiments described above. However, for the sake of completeness, in the bush main body 55 of the second bush 12, in addition to the corner portion 70 described above, a portion that contacts the O-ring 56 does not have a sharp portion (acute angle portion). It is preferable to do. For example, in each fitting groove (first groove) 57, it is preferable to chamfer the corner portion 74 (see FIG. 15) between the side surface 57B orthogonal to the bottom surface 57A and the notch 61 or the second groove 72.

The present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the claims.
For example, the first bush 11 also has the same configuration as the second bush 12 (side-view C-type configuration), and both the first bush 11 and the second bush 12 attach the rack shaft 8 to the pinion 7A side. You may be in force. Although the O-ring 56 is bent and attached to the second bush 12, the second bush 12 may be attached even if an elastic body having a shape other than the O-ring (for example, a block shape) is attached to the outer peripheral surface 55 </ b> A of the bush body 55. Can bias the rack shaft 8 toward the pinion shaft 7.

  Further, even if a general rack bush (for example, a rack bush having a cylindrical shape and no O-ring 46) is used for the rack bush (here, the first bush 11) disposed at a position far from the pinion shaft 7. Good.

  DESCRIPTION OF SYMBOLS 1 ... Steering device, 7 ... Pinion shaft, 8 ... Rack shaft, 9 ... Housing, 11 ... 1st bush, 12 ... 2nd bush, 55 ... Bush main body, 55A ... Outer peripheral surface, 55B ... Inner peripheral surface, 56 ... O Ring, 57 ... fitting groove (first groove), 61 ... notch, 70 ... corner, 72 ... second groove, 73 ... third groove, 92 ... second end

Claims (7)

A pinion shaft, a rack shaft disposed in a direction intersecting with the pinion shaft, a housing that accommodates these shafts, and disposed within the housing with the pinion shaft interposed therebetween, and slidably supports the rack shaft. A rack and pinion type steering device comprising two bushes,
At least one of the two bushes is
A first groove extending in the circumferential direction and a second groove extending in the axial direction at a position avoiding the first groove, the C-shaped side view being disposed between the rack shaft and the housing at one end of the housing; Bush body formed on the outer peripheral surface,
A part of the bushing body is fitted into the first groove so as to protrude from the outer peripheral surface of the bushing body, and is sandwiched between the bushing body and the housing, and the rack shaft is directed to the pinion shaft through the bushing body. An elastic member for biasing,
And a rack and pinion type steering device.   The third groove extending in the axial direction while being recessed toward the second groove is formed at a position on the inner peripheral surface of the bushing body that coincides with the second groove in the circumferential direction. The rack and pinion type steering device as described. A pinion shaft, a rack shaft disposed in a direction intersecting with the pinion shaft, a housing that accommodates these shafts, and disposed within the housing with the pinion shaft interposed therebetween, and slidably supports the rack shaft. A rack and pinion type steering device comprising two bushes,
At least one of the two bushes is
It is a C-type in a side view, and is disposed between the rack shaft and the housing at one end of the housing. A fitting groove extending in the circumferential direction is formed on the outer peripheral surface and a notch extending in the axial direction is formed. Bush body,
Part of the bushing body is fitted into the fitting groove so as to protrude from the outer peripheral surface of the bushing body, and is sandwiched between the bushing body and the housing, and the rack shaft is directed to the pinion shaft through the bushing body. An elastic member for biasing,
Including
A rack and pinion type steering device, wherein a corner portion intersecting with the notch is chamfered in the fitting groove.   The rack-and-pinion-type bush according to any one of claims 1 to 3, wherein the bush having the C-shaped bush body in a side view is disposed at an end of the housing on the pinion shaft side. Steering device. A bush supporting a rack shaft of a rack and pinion type steering device,
The first groove extending in the circumferential direction and the second groove extending in the axial direction at a position avoiding the first groove are formed on the outer peripheral surface, and the rack shaft is formed on the inner peripheral surface side. A bush body to be inserted;
An elastic member fitted into the first groove such that a part protrudes from the outer peripheral surface of the bush body;
A bush for a rack shaft, comprising:   6. A third groove extending in the axial direction while being recessed toward the second groove is formed at a position on the inner peripheral surface of the bushing body that coincides with the second groove in the circumferential direction. Bush for rack shaft as described. A bush supporting a rack shaft of a rack and pinion type steering device,
A bush main body that is C-shaped in a side view, has a fitting groove extending in the circumferential direction formed on the outer peripheral surface and a notch extending in the axial direction, and the rack shaft is inserted into the inner peripheral surface side; ,
An elastic member that is fitted into the fitting groove so that a part protrudes from the outer peripheral surface of the bush body;
Including
A bush for a rack shaft, wherein a corner portion intersecting with the notch is chamfered in the fitting groove.

Images