JP2010254080A - Rack shaft support device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rack shaft support device which can improve a steering feeling and prevent the generation of abnormal sound. <P>SOLUTION: A support yoke 18 is held in a holding hole 17 formed in a yoke housing 16 so as to be retractable in the depth direction X2. The support yoke 18 supports a rack shaft 8 so as to be movable in the axial direction of the rack shaft 8. The support yoke 18 is urged toward the rack shaft 8 side by an urging member 34. The support yoke 18 includes a pair of end parts 20 and 21 extending nearer to a pinion 7 side than to a central axis C1 of the rack shaft 8 with respect to the depth direction X2. A pair of end parts 20 and 21 are arranged at both sides with the rack shaft 8 sandwiched between them. A minimum interval D3 between the one pair of end parts 20 and 21 is smaller than a maximum width D5 of the rack shaft 8 with respect to a prescribed parallel direction X3 orthogonal to the depth direction X2. On an outer peripheral surface 18a of the support yoke 18, a protrusion 39 is formed which can abut on a peripheral surface 17b of the holding hole 17. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rack shaft support device.

Usually, a rack and pinion type steering device is provided with a rack shaft support device (see, for example, Patent Documents 1 and 2).
The rack shaft support device has a support yoke that supports the rack shaft so as to be slidable in the axial direction of the rack shaft. This support yoke is accommodated in the holding hole of the cylindrical housing, and can advance and retreat in the depth direction of the holding hole. The support yoke presses the rack shaft against the pinion by being biased toward the rack shaft by the biasing member. The support yoke has a pair of end portions extending to the pinion side. The pair of end portions are disposed on both sides of the rack shaft.

Japanese Utility Model Publication 2-65675 Japanese Utility Model Publication No. 4-43574

In a rack and pinion type steering device, each of the rack and the pinion may be a helical gear. In such a configuration, as the pinion rotates, a force (thrust force) in a direction parallel to the axial direction of the pinion acts on the rack shaft.
When a force in a direction parallel to the axial direction of the pinion (hereinafter referred to as a parallel direction in this section) acts on the rack shaft, the rack shaft tends to move in the parallel direction. That is, the rack shaft tends to move in the parallel direction during left steering or right steering.

When such a movement occurs, a difference occurs in steering torque between right steering and left steering. If there is a difference in steering torque between right steering and left steering, the movement of the steering wheel when the steering wheel is returned to the position in the straight traveling state, that is, the steering wheel return is also different between the right steering and the left steering. There is a difference between cases. As a result, the steering feeling becomes worse.
The support yoke of Patent Document 2 includes a pair of support surfaces that face each other across the center of the rack shaft. The pair of support surfaces sandwich the rack shaft in the parallel direction so as to sandwich the center of the rack shaft. Thereby, it can suppress with a support yoke that a rack axis | shaft moves to the said parallel direction. As a result, it is possible to prevent a difference in steering torque between right steering and left steering.

However, when the rack shaft vibrates in the advancing / retreating direction of the support yoke due to input from the wheels, for example, when traveling on a rough road, the rack shaft and the support yoke are moved away from each other for a moment. As a result, rattling occurs between the rack shaft and the support yoke, resulting in abnormal noise.
In addition, if there is a gap between the support yoke and the peripheral surface of the housing accommodation hole, the support yoke will collide with the peripheral surface to generate noise.

  Accordingly, an object of the present invention is to provide a rack shaft support device that can improve the steering feeling and prevent the generation of abnormal noise.

  In order to achieve the above object, the present invention holds a rack shaft in a holding hole (17) formed in a housing (16) so as to be able to advance and retreat in the depth direction (X2) of the holding hole. A rack shaft support member (18) that is supported so as to be movable in the axial direction (X1), and a threaded engagement (17c) formed on the peripheral surface (17b) of the inlet (17a) of the holding hole. A member (31, 31H), and a biasing member (34) interposed between the sealing member and the rack shaft support member and biasing the rack shaft support member toward the rack shaft, The rack shaft support member includes a pair of end portions (20, 21; 20G, 21G) extending from the center (C1) of the rack shaft to the pinion (7a) side in the depth direction, and the pair of end portions Are arranged on both sides of the rack shaft, and the depth direction In the orthogonal direction (X3), the minimum distance (D7) between the pair of end portions is smaller than the maximum width (D5) of the rack shaft, and the outer surface (18b) of the rack shaft support member. The rack shaft support device (15) is characterized in that a projection (39; 39A; 39B) capable of contacting the peripheral surface of the holding hole is formed (claim 1).

  According to the present invention, the pair of end portions sandwich the rack shaft so as to sandwich the center of the rack shaft. Thereby, it can control that a rack axis moves to a rack axis support member about a direction parallel to the axial direction of a pinion. As a result, it is possible to suppress a difference in steering torque acting on the pinion between left steering and right steering. Therefore, the movement of the steering member when returning the steering member to the position in the straight traveling state, that is, the so-called steering wheel return can be made the same in the case of right steering and the case of left steering. Thereby, an excellent steering feeling can be realized.

  Further, with respect to a direction orthogonal to the depth direction, the minimum distance between the pair of end portions is made smaller than the maximum width of the rack shaft. Thereby, since the rack shaft support member can hold the rack shaft from both sides in the depth direction, the rack shaft support member and the rack shaft can be prevented from being separated in the depth direction. Therefore, for example, when traveling on a rough road, the rack shaft and the rack shaft support member can be prevented from separating even when the rack shaft vibrates in the depth direction of the holding hole due to input from the wheels (reverse input). . As a result, rattling between the rack shaft and the rack shaft support member can be suppressed. Therefore, abnormal noise due to contact between the rack shaft and the rack shaft support member can be suppressed.

  Further, the protrusion formed on the outer surface of the rack shaft support member is in contact with the peripheral surface of the holding hole. Thereby, since it can suppress that a rack shaft supporting member rattles with respect to the surrounding surface of a holding hole, generation | occurrence | production of abnormal noise can be suppressed more reliably. Further, since only the protrusions protruding from the outer surface of the rack shaft support member are brought into contact with the peripheral surface of the holding hole, the catch between the rack shaft support member and the peripheral surface of the holding hole can be reduced. Thereby, the smooth forward / backward movement of the rack shaft support member can be realized.

  For example, the protrusions may be provided at both ends of the outer surface of the rack shaft support member in a direction parallel to the axial direction of the pinion. In this case, the force received by the rack shaft in a direction parallel to the axial direction of the pinion can be reliably received by the contact between these protrusions and the peripheral surface of the holding hole. Thereby, it can suppress more reliably that a rack axis | shaft moves to the direction parallel to the axial direction of a pinion.

Further, for example, when the protrusion is provided in the vicinity of the outer surface of the pair of end portions, it is possible to more reliably suppress the pair of end portions from rattling against the inner surface of the holding hole. As a result, it is possible to more reliably prevent the rack shaft sandwiched between the pair of end portions from moving in a direction parallel to the axial direction of the pinion.
In the present invention, the pair of end portions includes a facing surface (40; 40D) facing the outer peripheral surface (18b) of the rack shaft, and at least a part of the facing surface is the outer periphery of the rack shaft. In some cases, the shape is in line with the shape of the surface (claim 2). In this case, the rack shaft holding member can always hold the rack shaft from both sides in the depth direction. Thereby, it is possible to more reliably suppress the rack shaft from being displaced relative to the rack shaft holding portion in the depth direction of the holding hole.

  In the present invention, the rack shaft support member includes a sliding contact surface (43; 43C; 43D; 43E) on which the outer peripheral surface of the rack shaft is slidably contacted, and a sliding contact surface adjacent to the sliding contact surface. And a lubricant reservoir (51) that is recessed with respect to the surface (claim 3). In this case, sliding resistance between the rack shaft and the rack shaft support member can be further reduced, and the rack shaft can be displaced more smoothly in the axial direction of the rack shaft.

In the present invention, the sliding contact surface may include a radially extending portion (45) extending radially about the central axis (C3) of the rack shaft support member parallel to the depth direction (claims). 4).
In this case, a sufficient contact area between the rack shaft and the sliding contact surface can be secured in the circumferential direction of the rack shaft. Thereby, the rack shaft can be securely gripped. Further, by forming the slidable contact surface radially, the contact area between the slidable contact surface and the outer peripheral surface of the rack shaft can be made smaller than when the slidable contact surface is simply a curved surface. Accordingly, the sliding resistance of the rack shaft can be further reduced.

  Further, in the present invention, the pair of end portions includes a facing surface (40D) facing the outer peripheral surface of the rack shaft, and when viewed along the depth direction, the facing surface is an axis of the rack shaft. There is a case in which it is curved away from the rack shaft as it goes from the central part (61) to the end part (62, 63) with respect to the direction (Claim 5). In this case, the contact area between the sliding contact surface and the outer peripheral surface of the rack shaft can be reduced. Accordingly, the sliding resistance of the rack shaft can be further reduced.

  In the above description, 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.

It is a mimetic diagram showing a schematic structure of a steering device for vehicles provided with a rack axis support device concerning one embodiment of the present invention. It is sectional drawing of the principal part of FIG. 1, and mainly shows the rack and pinion mechanism and the rack shaft support apparatus. It is a bottom view of a support yoke. FIG. 3 is a partially enlarged view of FIG. 2. (A) is a side view of the main part around the support yoke, (b) is a side view of the main part around the support yoke as viewed along the arrow Vb in FIG. FIG. 5C is a side view of the main part around the support yoke as viewed along the arrow Vc in FIG. FIG. 3 is a partially enlarged view of FIG. 2. It is a top view of the principal part of another embodiment of this invention. It is a side view of the principal part of further another embodiment of this invention. It is a side view of the principal part of further another embodiment of this invention. (A), (b) is sectional drawing of the principal part of further another embodiment of this invention, respectively. (A), (b) is sectional drawing of the principal part of further another embodiment of this invention, respectively. (A) is sectional drawing and side view of the principal part of further another embodiment of this invention, (b), (c) is respectively the principal part of another embodiment of this invention. It is sectional drawing. (A) is sectional drawing of the principal part of another embodiment of this invention, (b) is a typical perspective view of the principal part of Fig.13 (a). It is a side view which shows a part of principal part of another embodiment of this invention in a cross section. It is sectional drawing of the principal part which follows the XV-XV line | wire of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram illustrating a schematic configuration of a vehicle steering apparatus 1 including a rack shaft support device according to an embodiment of the present invention. Referring to FIG. 1, a vehicle steering apparatus 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, an intermediate shaft 5 connected to the steering shaft 3 via a universal joint 4, A pinion shaft 7 connected to the shaft 5 via a universal joint 6 and a pinion 7 a provided at an end of the pinion shaft 7 are provided. Further, the vehicle steering apparatus 1 has a rack shaft 8 as a steered shaft that has a rack 8a that meshes with the pinion 7a and extends in the left-right direction of the vehicle. The pinion shaft 7 and the rack shaft 8 constitute a rack and pinion mechanism A as a steering mechanism.

  The rack shaft 8 is supported in a rack housing 9 fixed to the vehicle body via a plurality of bearings (not shown), and can reciprocate linearly along the axial direction X1 of the rack shaft 8. A pinion housing 10 is provided in the vicinity of the rack housing 9. A pinion 7 a is accommodated in the pinion housing 10. Both ends of the rack shaft 8 protrude to both sides of the rack housing 9. A tie rod 11 is coupled to each end of the rack shaft 8. Each tie rod 11 is connected to a corresponding steered wheel 12 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 of the rack shaft 8 along the axial direction X1 of the rack shaft 8 by the pinion 7a and the rack 8a. Thereby, the turning of the steered wheel 12 is achieved.
FIG. 2 is a cross-sectional view of the main part of FIG. 1, and mainly shows the rack and pinion mechanism A and the rack shaft support device 15. 1 and 2, the pinion shaft 7 is rotatable to a cylindrical pinion housing 10 via a first bearing 13 made of a ball bearing and a second bearing 14 made of a cylindrical roller bearing. It is supported by. A pinion 7 a is disposed between the first bearing 13 and the second bearing 14. Thereby, the pinion 7a is supported at both ends. The pinion 7 a of the pinion shaft 7 and the rack 8 a of the rack shaft 8 are meshed with each other in the pinion housing 10. Each of the pinion 7a and the rack 8a is a lot.

The rack shaft 8 has a D-shaped cross section. The outer peripheral surface 8b of the rack shaft 8 includes a rack forming portion 8c in which the rack 8a is formed and an arcuate portion 8d.
The arcuate portion 8d includes a part of the cylindrical surface. The central axis of the arcuate portion 8d is the central axis C1 of the rack shaft 8.
The vehicle steering apparatus 1 includes a rack shaft support device 15 that supports the rack shaft 8 in a biased state toward the pinion shaft 7. The rack shaft 8 is supported by a support yoke 18 (to be described later) of the rack shaft support device 15 and a bearing (not shown) provided in the rack housing 9 in the axial direction X1 of the rack shaft 8 (in FIG. It is supported so as to be movable.

  The rack shaft support device 15 includes a yoke housing 16 having a holding hole 17 formed of a circular hole, a support yoke 18 as a rack shaft support member that is held in the holding hole 17 and supports the rack shaft 8, and an inlet of the holding hole 17. And a sealing member 31 that is fixed to 17a and seals the inlet 17a. The rack shaft support device 15 includes a biasing member 34 that is interposed between the support yoke 18 and the sealing member 31 and elastically biases the support yoke 18 toward the rack shaft 8.

Of the rack housing 9, the portion 9 a near the pinion housing 10, the pinion housing 10, and the yoke housing 16 are formed using a single material, and are arranged so as to cross each other.
Referring to FIG. 2, the yoke housing 16 is disposed on the opposite side of the pinion shaft 7 with the rack shaft 8 interposed therebetween, and has a cylindrical shape. A central axis C2 of the holding hole 17 of the yoke housing 16 is orthogonal to the central axis C1 of the rack shaft 8 and is orthogonal to the central axis C5 of the pinion shaft 7. The center axis C1 of the rack shaft 8 and the center axis C5 of the pinion shaft 7 are shifted from each other by 90 degrees around the center axis C2 of the holding hole 17. A direction along the central axis C <b> 2 of the holding hole 17 is a depth direction X <b> 2 of the holding hole 17.

A female screw 17 c as a threaded portion is formed on the inlet 17 a side of the holding hole 17 in the peripheral surface 17 b of the holding hole 17. The sealing member 31 is screwed into the female screw 17c.
The sealing member 31 has a column shape. A male screw 31 a is formed on the outer periphery of the sealing member 31. The male screw 31a of the sealing member 31 is screwed into the female screw 17c of the holding hole 17 and fixed.

A lock nut 32 is screwed to the male screw 31 a of the sealing member 31. The sealing member 31 is fixed to the yoke housing 16 by the lock nut 32 being pressed against the end surface 16 a of the yoke housing 16.
The sealing member 31 is provided with a tool engagement hole 33 formed of a polygonal hole. The sealing member 31 can be rotated by engaging a tool (not shown) in the tool engagement hole 33.

The biasing member 34 is composed of a compression coil spring as an elastic member, for example. The compression coil spring is interposed between the sealing member 31 and the support yoke 18 in a compressed state. Further, a gap D <b> 1 for absorbing fluctuations is secured between the sealing member 31 and the bottom surface 18 b of the support yoke 18.
The support yoke 18 supports the rack shaft 8 so as to be movable in the axial direction X1 of the rack shaft 8. The support yoke 18 is formed using, for example, an aluminum alloy, a sintered body, a synthetic resin material, or the like. Examples of the synthetic resin material include engineering plastics such as polyamide-based resin (resin mainly composed of polyamide resin).

The support yoke 18 is held by the yoke housing 16 in the holding hole 17, and can move forward and backward in the depth direction X <b> 2 with respect to the holding hole 17.
The support yoke 18 is integrally formed using a single material. The outer peripheral surface 18a as the outer surface of the support yoke 18 is formed in a cylindrical shape as a whole.
The support yoke 18 includes a cylindrical first portion 23 adjacent to the sealing member 31, a pair of second portions 26 and 27 extending from the first portion 23 toward the pinion 7a, and a second portion 26, 27 and a pair of end portions 20 and 21 extending from the pinion 7a side. With respect to the depth direction X <b> 2, the first portion 23 forms a portion from the bottom surface 18 b of the support yoke 18 to the opposing surface 40 described later.

  On the outer peripheral surface 18b of the support yoke 18 in the first portion 23, for example, two annular grooves 24 are formed side by side in the depth direction X2. The annular groove 24 is disposed near one end of the outer peripheral surface 18b. An O-ring 54 formed using an elastic member such as rubber is fitted in each annular groove 24. A part of each O-ring 54 protrudes from the annular groove 24 and elastically contacts the peripheral surface 17 b of the holding hole 17. As a result, it is possible to prevent the support yoke 18 from making shocking contact with the peripheral surface 17b of the holding hole 17 and generating abnormal noise. Note that the number of parts of the rack shaft support device 15 may be reduced by eliminating the O-ring 54.

  FIG. 3 is a bottom view of the support yoke 18. With reference to FIG. 2 and FIG. 3, a plurality of pillar portions 28 are provided inside the first portion 23. The column portions 28 are radially arranged around the center axis C3 of the first portion 23 of the support yoke 18 (hereinafter simply referred to as the center axis C3 of the support yoke 18) inside the first portion 23. A plurality of (for example, eight) pillar portions 28 are provided at equal intervals in the circumferential direction of the first portion 23.

  Each column portion 28 includes a short piece portion 29 having a relatively short length in the radial direction of the first portion 23 and a long piece portion 30 having a relatively long length in the radial direction of the first portion 23. It is out. The short piece portion 29 is disposed inside the first portion 23. A bottom surface 18 b of the support yoke 18 is formed by one side surface of the first portion 23 and one side surface of the short piece portion 29. The long piece portion 30 is adjacent to the short piece portion 29 in the depth direction X <b> 2, and is disposed inside the first portion 23 and inside the second portions 26 and 27. An accommodation recess 35 is formed by the inner side surface 29 a of each short piece portion 29 and one side surface 30 a of each long piece portion 30.

An annular reinforcing bush 36 is housed in the housing recess 35. The reinforcing bush 36 is for reducing the strength against buckling of the support yoke 18 and the internal stress of the support yoke 18.
FIG. 4 is a partially enlarged view of FIG. Referring to FIG. 4, the reinforcing bush 36 includes a metal bush main body 37 such as an aluminum alloy, and an elastomeric resin buffer member 38 fixed to one end of the bush main body 37. The bush main body 37 is held by the support yoke 18 by the outer peripheral surface of the bush main body 37 engaging with the inner side surface 29 a of the short piece portion 29 of each column portion 28.

  An annular convex portion 38 a is formed on one side surface of the buffer member 38 facing the sealing member 31. The convex portion 38a protrudes from the bottom surface 18b. Contact between the convex portion 38a of the buffer member 38 and the sealing member 31 prevents the support yoke 18 and the sealing member 31 from impactingly contacting each other. Thereby, the contact noise between the support yoke 18 and the sealing member 31 is reduced.

Referring to FIG. 2, the urging member 34 is accommodated in the accommodating recess 35, and is opposed to one side surface 30 a of the long piece portion 30 and the sealing member 31 facing the one side surface 30 a of the long piece portion 30. Engage with the surface. As a result, the support yoke 18 is urged toward the rack shaft 8 along the depth direction X2.
FIG. 5A is a side view of the main part around the support yoke 18, and FIG. 5B shows the main part around the support yoke 18 viewed along the arrow Vb in FIG. 5A. 5C is a side view, and FIG. 5C is a side view of the main part around the support yoke 18 viewed along the arrow Vc in FIG. 5B. In addition, in FIG.5 (c), a part is shown with the dashed-two dotted line.

  With reference to FIGS. 5A and 5B, the second portions 26 and 27 of the support yoke 18 are connected to the first portion 23. With respect to the depth direction X <b> 2, the pair of second portions 26 and 27 are disposed from the boundary portion 72 with the first portion 23 to the central axis C <b> 1 of the rack shaft 8. A pair of these second portions 26 and 27 are provided apart from each other in a direction parallel to the axial direction X5 of the pinion shaft 7. Each of the second portions 26 and 27 is formed in a symmetrical shape, and tapers as it advances toward the pinion 7a along the depth direction X2.

  The pair of end portions 20 and 21 are extended from the corresponding second portions 26 and 27 toward the pinion 7a. With respect to the depth direction X <b> 2, the pair of end portions 20, 21 extends to the pinion 7 a side with respect to the central axis C <b> 1 of the rack shaft 8. Each of the pair of end portions 20 and 21 tapers as it advances toward the pinion 7a along the depth direction X2. As shown in FIG. 5A, when viewed so that the center axis C1 of the rack shaft 8 and the center axis C3 of the support yoke 18 are orthogonal to each other, one second portion 26, one end portion 20, Has a chevron shape as a whole. Although not shown, similarly, the other second portion 27 and the other end portion 21 have a chevron shape as a whole.

  5A and 5B, with respect to a direction X3 parallel to the axial direction X5 of the pinion shaft 7 (hereinafter referred to as a parallel direction X3), the pair of end portions 20 and 21 and the pair of second portions The portions 26 and 27 are arranged on both sides of the rack shaft 8 so as to sandwich the central axis C1 of the rack shaft 8. A hemispherical protrusion 39 is provided on the bottom surface 18 b of the support yoke 18 at each of the pair of end portions 20 and 21 and on the outer peripheral surface 18 a of the support yoke 18 in the first portion 23. The protrusion 39 is in contact with the peripheral surface 17 b of the holding hole 17.

The protrusion 39 restricts the support yoke 18 from moving relative to the peripheral surface 17b of the holding hole 17 in the parallel direction X3. The protrusion 39 is for reducing the resistance between the outer peripheral surface 18 a of the support yoke 18 and the peripheral surface 17 b of the holding hole 17.
A plurality of protrusions 39a and 39b are formed in a staggered manner in the vicinity of the pair of end portions 20 and 21 in the outer peripheral surface 18a of the pair of second portions 26 and 27, respectively. Further, on the outer peripheral surface 18a of the first portion 23, a plurality of protrusions 39c and 39d are formed in a staggered manner at each of a pair of end portions in the parallel direction X3. The protrusions 39a and 39b may be arranged so as to be aligned straight in the depth direction X2 in each of the pair of second portions 26 and 27. Further, the protrusions 39c and 39d may be arranged in the first portion 23 so as to be aligned straight in the depth direction X2.

The protrusion 39a of one second portion 26 and the protrusion 39b of the other second portion 27 are arranged to face each other in the parallel direction X3. The protrusion amount D6 of each protrusion 39a to 39d from the outer peripheral surface 18a is, for example, about 0.03 mm to 0.05 mm.
FIG. 6 is a partially enlarged view of FIG. With reference to FIG. 5C and FIG. 6, the pair of end portions 20, 21 includes a first facing surface 41 that faces the arcuate portion 8 d of the rack shaft 8. Further, the pair of second portions 26 and 27 includes a second facing surface 42 that faces the arcuate portion 8 d of the rack shaft 8. The opposing surface 40 of the support yoke 18 is formed by the first opposing surfaces 41 and 41 of the pair of end portions 20 and 21 and the second opposing surfaces 42 and 42 of the pair of second portions 26 and 27. Yes. The opposing surface 40 constitutes a part of the arc surface as a whole, and opposes the arc-shaped portion 8d.

The facing surface 40 includes a sliding contact surface 43 slidably contacting the arcuate portion 8 d of the rack shaft 8 and a lubricant reservoir 51 adjacent to the sliding contact surface 43 and recessed with respect to the sliding contact surface 43. Yes.
The sliding contact surface 43 may be coated. In this case, the coefficient of friction is reduced. For example, when the support yoke 18 is formed of a polyamide resin such as PA9T, the sliding contact surface 43 is coated. In addition, this coating process does not need to be performed. The sliding contact surface 43 is formed in a shape along the shape of the arc-shaped portion 8 d of the rack shaft 8, and includes an inner annular portion 44, a radially extending portion 45, and an outer annular portion 46.

The inner annular portion 44 is formed on the second opposing surface 42 of the pair of second portions 26 and 27, and is formed in an annular shape centering on the central axis C <b> 3 of the support yoke 18.
The radially extending portion 45 is formed in each of the second portions 42 and 42 and is connected to the outer periphery of the inner annular portion 44. The radially extending portions 45 are formed radially about the central axis C3 of the support yoke 18. The central axis C3 of the support yoke 18 is disposed so as to coincide with the central axis C2 of the holding hole 17.

  The outer annular portion 46 is formed on the first opposing surfaces 41 and 41 of the pair of end portions 20 and 21 and the second opposing surfaces 42 and 42 of the pair of second portions 26 and 27. The outer annular portion 46 is an annular portion formed substantially concentrically with the inner annular portion 44. A radially extending portion 45 is connected to the inner periphery of the outer annular portion 46. The outer annular portion 46 is formed in the entire area of each first facing surface 41, 41. Thereby, all of the 1st opposing surfaces 41 and 41 of a pair of edge parts 20 and 21 become a shape in alignment with the circular arc-shaped part 8d.

  The lubricant reservoir 51 is for holding a lubricant such as grease and is formed on the second facing surface 42. The lubricant reservoir 51 includes a first lubricant reservoir 52 formed on the inner side of the inner annular portion 44 and a second lubricant reservoir 53 arranged alternately with the radially extending portions 45 in the circumferential direction of the support yoke 18. And. The grease stored in the lubricant reservoir 51 is supplied to the arc-shaped portion 8 d of the rack shaft 8, thereby smoothly sliding the arc-shaped portion 8 d of the rack shaft 8 and the sliding contact surface 43 of the support yoke 18. it can.

Referring to FIG. 6, a distance D2 between the first opposing surfaces 41 and 41 of the pair of end portions 20 and 21 continuously changes along the depth direction X2. In addition, this space | interval D2 means the space | interval between the 1st opposing surfaces 41 and 41 regarding the parallel direction X3 orthogonal to the depth direction X2.
Here, a reference plane B that includes the central axis C1 of the rack shaft 8 and is orthogonal to the central axis C2 of the holding hole 17 and the central axis C3 of the support yoke 18 is defined. The reference plane B separates the pair of end portions 20 and 21 and the pair of second portions 26 and 27. The diameter of the rack shaft 8 in the reference plane B is the maximum width D5 of the rack shaft 8.

The distance D2 between the pair of first opposing surfaces 41, 41 becomes narrower as it goes to the pinion shaft 7 side along the depth direction X2. The protrusion amount D6 from the reference plane B of the pair of first facing surfaces 41, 41 along the depth direction X2 is, for example, about 1 to 2 mm.
Of the pair of first facing surfaces 41, 41, the distance D2 closest to the pinion 7a in the depth direction X2 is the minimum distance D3 between the pair of end portions 20, 21. The minimum distance D3 is smaller than the maximum width D5 of the rack shaft 8 (D3 <D5).

With the above configuration, the entire sliding contact surface 43 is in sliding contact with the arcuate portion 8 d of the rack shaft 8 in the circumferential direction of the rack shaft 8. When viewed along the axial direction X <b> 1 of the rack shaft 8, the slidable contact surface 43 holds a range larger than half of the outer peripheral surface 8 b of the rack shaft 8 with respect to the circumferential direction of the rack shaft 8.
As described above, according to the present embodiment, the pair of end portions 20 and 21 of the support yoke 18 sandwich the rack shaft 8 so as to sandwich the center axis C <b> 1 of the rack shaft 8. Thereby, it is possible to restrict the rack shaft 8 from moving with respect to the support yoke 18 in the parallel direction X3. Thereby, it can suppress that a difference arises in the steering torque which acts on the pinion 7a between the time of left steering and the time of right steering. Therefore, the movement of the steering member 2 when the steering member 2 is returned to the position in the straight traveling state, that is, the so-called steering wheel return can be made the same in the case of the right steering and the case of the left steering. Thereby, an excellent steering feeling can be realized.

  Further, with respect to the parallel direction X3, the minimum distance D3 between the pair of end portions 20 and 21 is made smaller than the maximum width D5 of the rack shaft 8 (D3 <D5). Thereby, since the support yoke 18 can hold | maintain the rack shaft 8 from both sides of the depth direction X2, it can suppress that the support yoke 18 and the rack shaft 8 separate in the depth direction X2. Therefore, for example, when traveling on a rough road, the rack shaft 8 and the support yoke 18 are prevented from separating even when the rack shaft 8 vibrates in the depth direction X2 due to input from the steered wheels 12 (reverse input). it can. As a result, rattling between the rack shaft 8 and the support yoke 18 can be suppressed. Therefore, abnormal noise due to contact between the rack shaft 8 and the support yoke 18 can be suppressed.

  Further, the protrusion 39 formed on the outer peripheral surface 18 a of the support yoke 18 is in contact with the peripheral surface 17 b of the holding hole 17. Thereby, since it can suppress that the support yoke 18 rattles with respect to the surrounding surface 17b of the holding hole 17, generation | occurrence | production of abnormal noise can be suppressed more reliably. Furthermore, since only the protrusions 39 (protrusions 39a to 39d) protruding from the outer peripheral surface 18a of the support yoke 18 are brought into contact with the peripheral surface 17b of the holding hole 17, the support yoke 18 and the peripheral surface 17b of the holding hole 17 are in contact with each other. The catch can be reduced. Thereby, the smooth forward / backward movement of the support yoke 18 can be realized.

  Further, protrusions 39 are provided at both ends of the outer peripheral surface 18a of the support yoke 18 in the parallel direction X3. Thereby, the force received by the rack shaft 8 in the parallel direction X3 can be reliably received by the contact between the protrusion 39 and the peripheral surface 17b of the holding hole 17. Thereby, it can suppress more reliably that the rack shaft 8 moves to the parallel direction X3. Thereby, the protrusion 39 can exhibit the same function as the O-ring 54, that is, the function of suppressing the movement of the rack shaft 8 and the support yoke 18 in the parallel direction X3 with respect to the holding hole 17. As a result, it is possible to reliably suppress a difference in steering torque acting on the pinion 7a during left steering or right steering. Thereby, as described above, an excellent steering feeling can be realized.

Further, the protrusion 39 is provided in the vicinity of the pair of end portions 20 and 21 among the pair of second end portions 26 and 27. Thereby, it can suppress more reliably that a pair of edge part 20 and 21 rattles with respect to the surrounding surface 17b of the holding hole 17. FIG. As a result, the rack shaft 8 sandwiched between the pair of end portions 20 and 21 can be more reliably suppressed from moving in the parallel direction X3.
Further, when the support yoke 18 is formed of a synthetic resin rich in elasticity, the protrusion 39 is provided, so that the peripheral surface 17b of the holding hole 17 of the yoke housing 16 can be provided regardless of the water absorption rate of the synthetic resin. It is possible to pack the space between.

  In addition, at least a part (all in the present embodiment) of the first facing surfaces 41 and 41 of the pair of end portions 20 and 21 is formed along the arcuate portion 8d of the outer peripheral surface 8b of the rack shaft 8. ing. Thereby, the support yoke 18 can always hold the rack shaft 8 from both sides in the depth direction X2. Thereby, it is possible to more reliably suppress the rack shaft 8 from being displaced relative to the support yoke 18 in the depth direction X2 of the holding hole 17.

Further, a lubricant reservoir 51 is provided in the support yoke 18. Thereby, the sliding resistance between the rack shaft 8 and the support yoke 18 can be further reduced, and the rack shaft 8 can be displaced smoothly in the axial direction X1 of the rack shaft 8.
Further, by providing the radially extending portion 45 of the sliding contact surface 43, it is possible to sufficiently ensure the contact length between the rack shaft 8 and the sliding contact surface 43 in the circumferential direction of the rack shaft 8. Thereby, the rack shaft 8 can be reliably gripped by the support yoke 18. Further, by forming a part of the slidable contact surface 43 radially, the contact area between the slidable contact surface 43 and the outer peripheral surface 8b of the rack shaft 8 can be reduced as compared with the case where the slidable contact surface 43 is a simple curved surface. . Therefore, the sliding resistance of the rack shaft 8 can be further reduced.

The present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the claims. In the following, differences from the above-described embodiment will be described, and the same components are denoted by the same reference numerals and description thereof will be omitted.
For example, as shown in FIG. 7, the protrusions 39 may be provided on the pair of end portions 18 c and 18 c of the outer peripheral surface 18 a of the support yoke 18 in the axial direction X <b> 1 of the rack shaft 8. The protrusion 39 may be provided over the entire circumference of the outer peripheral surface 18 a of the support yoke 18.

Further, instead of the protrusion 39, a truncated cone-shaped protrusion 39A may be provided as shown in FIG. Furthermore, as shown in FIG. 9, a belt-like projection 39 </ b> B (projection) extending in the circumferential direction of the support yoke 18 may be provided.
As shown in FIG. 10A, the arcuate portion 8d of the rack shaft 8 and the sliding contact surface 43C of the support yoke 18 may be in contact with each other only at three locations in the circumferential direction of the rack shaft 8. . In this case, the arcuate portion 8d of the rack shaft 8 is supported by the contact portions 55 in the circumferential portion of the rack shaft 8 and the three contact portions 55 in the central portion of the sliding contact surface 43C of the support yoke 18.

  Further, as shown in FIG. 10B, the arcuate portion 8d of the rack shaft 8 and the sliding contact surface 43D of the support yoke 18 may be in contact with each other only at four locations in the circumferential direction of the rack shaft 8. . In this case, the arcuate portion 8d of the rack shaft 8 is supported by the contact portions 56 in the middle portion of the sliding contact surface 43D of the support yoke 18 at both ends in the circumferential direction of the rack shaft 8 and at four intermediate portions. The four contact portions 56 are arranged symmetrically about a second reference plane B2 that includes the central axis C3 of the support yoke 18 and is orthogonal to the parallel direction X3.

  As shown in FIGS. 10A and 10B, when the number of contact portions between the arcuate portion 8d of the rack shaft 8 and the support yoke 18 in the circumferential direction of the rack shaft 8 is changed, The shape of the sliding contact surface of the support yoke 18 will be changed. As a result, the engagement force between the support yoke 18 and the rack shaft 8 can be changed. As a result, the preload applied to the rack shaft 8 by the support yoke 18 can be changed. Therefore, it is not necessary to change the urging force of the urging member 34 in order to change the preload.

  Furthermore, a first sheet 57 may be provided as shown in FIG. The first sheet 57 is obtained by applying a fluorine coating to the surface of a base material made of a synthetic resin, an aluminum alloy, or a sintered body. Most of the first sheet 57 is embedded in the first portion 23 of the support yoke 18. A part of the first sheet 57 is exposed from the first part 23 and constitutes a part of the second facing surface 42C.

  Further, as shown in FIG. 11B, an arc-shaped second sheet 58 may be provided. The second sheet 58 is formed using the same material as the first sheet 57. The second sheet 58 is attached to the pair of portions 20 and 21 and the pair of second portions 26 and 27 of the support yoke 18. One side surface of the second sheet 58 is a facing surface 40 </ b> D that faces the arcuate portion 8 d of the rack shaft 8.

  Furthermore, as shown in FIG. 12A, a third sheet 59 may be provided. The third sheet 59 is formed by pressing a metal plate. The surface of the metal plate is coated with diamond-like carbon (DLC). This coating may be performed before or after the metal plate is pressed. When viewed along the axial direction X1 of the rack shaft 8, the third sheet 59 is formed in a substantially Ω shape, and extends from the arcuate main portion 59a and the pair of end portions of the main portion 59a. And a pair of extended pieces 59b and 59c.

The main body portion 59 a is held by the pair of end portions 20 and 21 and the pair of second portions 26 and 27 of the support yoke 18. An inner side surface of the main body portion 59a is a sliding contact surface 43E.
Each extending piece 59b, 59c extends from the corresponding end of the main body 59a toward the peripheral surface 17b of the holding hole 17. Reinforcing ribs 60 are formed on the extended pieces 59b and 59c. Regarding the axial direction X1 of the rack shaft 8, the length of the third sheet 59 may be shorter than the length of the support yoke 18.

  In addition, as shown in FIG.12 (b), you may bend the front-end | tip of each extension piece 59bE and 59cE. In this case, the extended pieces 59bE and 59cE come into contact with the outer peripheral surface 18a of the pair of end portions 20 and 21, respectively. Each extending piece 59bE, 59cE is in contact with the peripheral surface 17b of the holding hole 17. Moreover, as shown in FIG.12 (c), you may use the spiral extension pieces 59bF and 59cF. Each extending piece 59bF, 59cF is in contact with the peripheral surface 17b of the holding hole 17.

  Further, as shown in FIGS. 13A and 13B, the first opposing surfaces 41G and 41G of the pair of end portions 20G and 21G of the support yoke 18 are curved when viewed along the depth direction X2. You may form in a shape. When viewed along the depth direction X2, each of the first facing surfaces 41G and 41G extends from the arcuate portion 8d of the rack shaft 8 toward the ends 62 and 63 from the central portion 61 with respect to the axial direction X1 of the rack shaft 8. is seperated. Thereby, a part of each 1st opposing surface 41G and 41G is made into the shape which follows the shape of the circular arc-shaped part 8d.

In this case, the contact area between the sliding contact surface 43G and the arcuate portion 8d of the rack shaft 8 can be reduced. Therefore, the sliding resistance of the rack shaft 8 can be further reduced.
Further, as shown in FIGS. 14 and 15, an intermediate member 64, a cam mechanism 65, a mainspring spring 66, and the like may be provided between the sealing member 31H and the support yoke 18. By these members, it is possible to further suppress the generation of abnormal sounds (rattle sounds) that accompany changes over time.

The mainspring spring 66 is for generating an urging force for moving the intermediate member 64 relative to the sealing member 31H.
One end 66a of the mainspring spring 66 is locked to a first engagement column 69 of the sealing member 31H formed on the sealing member 31H. The other end 66 b of the mainspring spring 66 is locked to a second engagement column 70 formed on the intermediate member 64. A torsional force is applied to the mainspring spring 66. The rotational force of the intermediate member 64 due to the twisting back of the mainspring spring 66 is converted by the cam mechanism 65 into a force that pushes the intermediate member 64 toward the support yoke 18.

The intermediate member 64 receives the biasing member 34 between the support yoke 18 and the sealing member 31H. The intermediate member 64 is accommodated in the holding hole 17 so as to be rotatable around the central axis C <b> 2 of the holding hole 17 and movable in the depth direction X <b> 2 of the holding hole 17. The intermediate member 64 includes a cylindrical portion 64 a that extends in the depth direction X <b> 2 of the holding hole 17.
The cam mechanism 65 projects from the spiral groove cam 68 formed on the outer periphery of the cylindrical portion 64a of the intermediate member 64 and the groove cam 68 that protrudes inside the cylindrical portion 67 formed on the sealing member 31H. And a cam projection 71 to be mated. It is sufficient that at least one cam protrusion 71 is provided, and in the present embodiment, the cam protrusions 71 are equally disposed at a plurality of circumferential positions of the sealing member 31H, for example, at two positions.

Further, the sealing member 31H, the intermediate member 64, and the mainspring spring 66 constitute a unit 75 as a partial assembly. The unit 75 can be assembled in the holding hole 17 integrally.
For example, in the unit 75 before being assembled into the holding hole 17, a predetermined amount of elastic deformation is applied to the mainspring spring 66 in advance, and the sealing member 31 </ b> H and the intermediate member 64 are provided in the circumferential direction of the sealing member 31 </ b> H. They are positioned at predetermined positions. In this state, the sealing member 31H and the intermediate member 64 are temporarily fixed by a pin (not shown) as a temporary fixing member. At the time of temporary fixing, the pin penetrates the sealing member 31 and the intermediate member 64 along the axial direction of the sealing member 31H. At this time, the pin protrudes from the one end face 64b of the intermediate member 64 by a predetermined amount, for example, 0.05 mm.

  The unit 75 in this state is assembled to the holding hole 17 in which the support yoke 18 is incorporated. At this time, the tip of the pin comes into contact with the bottom surface 18 b of the support yoke 18, so that the predetermined amount of gap is secured between the one end surface 64 b of the intermediate member 64 and the bottom surface 18 b of the support yoke 18. Next, after fixing the sealing member 31H with the lock nut 32, the pin is removed. Thereby, the predetermined amount of gaps can be set easily.

  In this case, as the wear of the sliding portion between the support yoke 18 and the rack shaft 8 progresses, the mainspring spring 66 is twisted back, so that the intermediate member 64 is rotated. As a result, the intermediate member 64 is driven to the support yoke 18 side by the action of the cam projection 71 of the sealing member 31H and the groove cam 68 of the intermediate member 64, whereby the meshing portion of the rack 8a and the pinion 7a is maintained over a long period of time. Can be maintained substantially constant. As a result, noise can be suppressed over a long period of time. Therefore, the steering feeling does not deteriorate as the pressing force of the meshing portion between the rack 8a and the pinion 7a changes.

7a ... pinion, 8 ... rack shaft, 8b ... outer peripheral surface of rack shaft, 15 ... rack shaft support device, 16 ... yoke housing (housing), 17 ... holding hole, 17a ... inlet of holding hole, 17b ... peripheral surface of inlet (Inner circumference), 17c ... internal thread (threaded portion), 18 ... support yoke (rack shaft support member), 18a ... outer circumferential surface (outer side), 20, 21, 20G, 21G ... pair of end portions, 31, 31H ... Sealing member, 34 ... biasing member, 39, 39A, 39B ... projection, 41, 41G ... first facing surface (facing surfaces of a pair of ends), 43, 43C, 43D, 43E ... sliding contact surface,
45 ... Radial extension part, 51 ... Lubricant reservoir, 61 ... Center part, 62, 63 ... End part, C1 ... Center axis of rack shaft (center of rack axis), C3 ... Center axis of support yoke (rack shaft support member) , D5... Rack axis maximum width, D3... Minimum interval, X1... Rack axis direction, X2. Depth direction, X3 .. parallel direction (direction perpendicular to depth direction).

Claims (5)

A rack shaft support member that is held in a holding hole formed in the housing so as to be movable back and forth in the depth direction of the holding hole, and supports the rack shaft movably in the axial direction of the rack shaft;
A sealing member screwed into a threaded portion formed on the peripheral surface of the inlet of the holding hole;
An urging member interposed between the sealing member and the rack shaft support member and urging the rack shaft support member toward the rack shaft;
The rack shaft support member includes a pair of end portions extending from the center of the rack shaft to the pinion side with respect to the depth direction, and the pair of end portions are disposed on both sides of the rack shaft,
With respect to a direction perpendicular to the depth direction, the minimum distance between the pair of end portions is smaller than the maximum width of the rack shaft,
A rack shaft support device, wherein a protrusion capable of contacting the peripheral surface of the holding hole is formed on an outer surface of the rack shaft support member. In Claim 1, the above-mentioned pair of end portions includes opposing surfaces facing the outer peripheral surface of the rack shaft,
At least a part of the facing surface has a shape that follows the shape of the outer peripheral surface of the rack shaft.   3. The rack shaft support member according to claim 1, wherein the rack shaft support member includes a sliding contact surface on which an outer peripheral surface of the rack shaft is slidably contacted, and a lubricant reservoir that is adjacent to the sliding contact surface and is recessed with respect to the sliding contact surface. And a rack shaft support device.   4. The rack shaft support device according to claim 3, wherein the sliding contact surface includes a radially extending portion extending radially about a central axis of the rack shaft support member parallel to the depth direction. In any one of Claims 1-4, a pair of said edge part contains the opposing surface facing the outer peripheral surface of the said rack shaft,
The rack shaft support device, wherein when viewed along the depth direction, the facing surface is curved away from the rack shaft as it goes from the center to the end in the axial direction of the rack shaft. .

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