JP2007083790A - Bearing device, and steering device having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device having supporting rigidity in the radial direction of a rack shaft and an excellent sliding characteristic in the axial direction thereof, and also to provide a steering device having the same. <P>SOLUTION: A steering device 1 has a rack shaft 6 and a housing 7 with the rack shaft 6 inserted therein. The rack shaft 6 is supported by a bearing device 11 held by a retaining hole 12 in the housing. The bearing device 11 includes: a bush 13 having a slit as an inner cylinder with the rack shaft 6 inserted therein; an outer cylinder 14 for surrounding the bush 13 with a predetermined space w in the radial direction A1; and an annular elastic member 15 which is elastically compressed in the radial direction A1 and interposed between the bush 13 and the outer cylinder 14. An outer circumferential surface 14a of the outer cylinder 14 is fitted to an inner circumferential surface 24b of the retaining hole 12, and retained. The friction coefficient of the outer circumferential surface 14a of the outer cylinder 14 with an inner circumferential surface 24b of the retaining hole 12 is larger than that of an inner circumferential surface 16b of the bush 13 with an outer circumferential surface 6a of the rack shaft 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bearing device and a steering device including the bearing device.

A rack-and-pinion type steering apparatus typically includes a rack shaft that moves in the axial direction by rotation of a steering member such as a steering wheel, and a housing that houses the rack shaft. The rack shaft is slidably supported in the housing by a bearing device held in the housing.
Some bearing devices include a cylindrical bush that slidably supports a rack shaft, and an elastic member interposed between the bush and the housing (for example, Patent Document 1).
JP 2004-183780 A

  However, in the invention described in Patent Document 1, the bush and the elastic member may move in the axial length direction together with the rack shaft with respect to the housing. In such a case, the bearing device may come off the housing. Even if a stopper is provided in the housing to restrict the movement of the bearing device, the sliding load of the rack shaft may fluctuate rapidly when the bearing device hits the stopper. Further, when the tightening margin of the elastic member with respect to the housing and the bush is increased, the movement of the bush and the elastic member can be restricted, but the sliding resistance of the rack shaft is increased.

  The present invention has been made based on such background, and has a bearing rigidity and a good sliding characteristic in the radial direction of the rack shaft in the radial direction, and the movement with respect to the housing is restricted, and the bearing apparatus. It aims at providing the steering device provided with.

  To achieve the above object, an inner cylinder (13) that slidably supports the shaft member (6) and an outer cylinder (14) surrounding the inner cylinder with a predetermined gap (w) in the radial direction (A1). ) And an annular elastic member (15) interposed between the inner cylinder and the outer cylinder in an elastically compressed state in the radial direction, and the inner cylinder intersects the circumferential direction (Z1). The elastic member is accommodated on the outer peripheral surface (16a) of the inner cylinder and the inner peripheral surface (14b) of the outer cylinder so as to oppose each other. The annular grooves (18a, 18b, 23a, 23b) are formed, respectively, and the outer peripheral surface (14a) of the outer cylinder is fitted and held in the inner peripheral surface (24b) of the holding hole (12) of the housing (7). The friction coefficient between the outer peripheral surface of the outer cylinder and the inner peripheral surface of the holding hole of the housing is the same as that of the inner peripheral surface of the inner cylinder. Bearing device being larger than the friction coefficient between the outer peripheral surface of the member is (11).

According to the present invention, the friction coefficient between the outer peripheral surface of the outer cylinder and the inner peripheral surface of the holding hole of the housing is made larger than the friction coefficient between the inner peripheral surface of the inner cylinder and the outer peripheral surface of the shaft member. The movement with respect to the housing can be restricted. Thereby, the favorable sliding characteristic of a shaft member can be acquired.
The invention according to claim 2 supports the steered shaft (6) as a shaft member extending in the left-right direction (X1) of the vehicle, and supports the steered shaft slidably in the axial length direction (Y1). A steering device (1) including the bearing device described above and a housing having a holding hole for holding the bearing device.

According to the present invention, by using the bearing device according to claim 1 for a steering device, it is possible to obtain good sliding characteristics of the steered shaft.
In the above description, the alphanumeric characters 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.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a schematic view schematically showing a rack and pinion type steering apparatus according to an embodiment of the present invention. Referring to FIG. 1, a rack and pinion type steering apparatus 1 includes an input shaft 3 to which a steering wheel 2 is connected, an output shaft 5 on which a pinion 4 is formed, and a rack shaft 6 as a steered shaft that meshes with the pinion 4. And a housing 7 through which the rack shaft 6 is inserted.

The input shaft 3 and the output shaft 5 are connected coaxially via a torsion bar 8. The input shaft 3 and the output shaft 5 rotate relative to each other with elastic torsion of the torsion bar 8 according to the steering torque applied from the steering wheel 2.
The rack shaft 6 extends in the left-right direction X1 (left-right direction in FIG. 1) of the vehicle (not shown), and meshes with the pinion 4 in the housing 7. Tie rods 9 are respectively connected to both ends of the rack shaft 6. The tie rods 9 are connected to the wheels 10a through knuckle arms 10, respectively. Further, the rack shaft 6 includes a rack yoke (not shown) that movably supports a peripheral surface of the rack shaft 6 opposite to the rack teeth, and a bearing device 11 that is held by the housing 7. It is slidably supported by.

Steering torque is applied to the steering wheel 2 and the pinion 4 rotates. As a result, the rack shaft 6 that meshes with the pinion 4 is moved in the axial direction Y1, and the steering angle of the wheel changes.
Next, the bearing device 11 that supports the rack shaft 6 will be described in detail.
FIG. 2 is an enlarged partial cross-sectional view schematically showing the bearing device and its periphery in FIG. 1, and FIG. 3 is a cross-sectional view schematically showing a bush of the bearing device in a free state. With reference to FIG. 2, the bearing device 11 is held in a holding hole 12 formed in the housing 7 in a state where the rack shaft 6 is inserted. Further, the bearing device 11 includes a bush 13 as an inner cylinder that is endless in the circumferential direction, an outer cylinder 14 that is endless in the circumferential direction, and a pair of annular elastic members interposed between the bush 13 and the outer cylinder 14. Member 15.

  The bush 13 as an inner cylinder is made of synthetic resin, and includes a cylindrical main body 16 and an annular flange 17 protruding outward from the one end of the main body 16 in the radial direction A1. A pair of annular grooves 18 a and 18 b extending in the circumferential direction Z <b> 1 of the main body 16 are formed on the outer peripheral surface 16 a of the main body 16. The rack shaft 6 is inserted into and supported by an insertion hole 19 that penetrates the main body 16 in the axial direction B1. As shown in FIG. 3, the diameter D <b> 1 of the insertion hole 19 is larger than the outer diameter D <b> 2 of the rack shaft 6 in the free state of the bush 13.

  In addition, a single slit (slit) 20 is formed in the main body 16, whereby the main body 16 has a pair of end portions 16 c on both sides sandwiching the slit 20 in the circumferential direction Z <b> 1. Specifically, the slit 20 extends from one end to the other end in the axial direction B1 of the main body 16 and intersects with a pair of axial portions 21 extending in the axial direction B1 of the main body 16 and the circumferential direction Z1 of the main body 16. And an inclined portion 22 extending in the direction. The pair of axial portions 21 extend from both ends in the axial direction B1 of the main body 16 and are connected to each other via the inclined portion 22.

  The bush 13 is elastically deformed by the slit 20, and the outer diameter and inner diameter of the bush 13 change. Further, in the state where the rack shaft 6 is inserted into the insertion hole 19 of the bush 13, the inner peripheral surface 16 b of the bush 13 and the outer peripheral surface 6 a of the rack shaft 6 are adjusted by adjusting the interval (slit width) t of the slit 20. And the inner peripheral surface 16b of the bush 13 is along the outer peripheral surface 6a of the rack shaft 6.

  Referring to FIG. 2 again, the outer cylinder 14 is formed in a cylindrical shape. A pair of annular grooves 23 a and 23 b extending in the circumferential direction Z <b> 1 of the outer cylinder 14 are formed on the inner peripheral surface 14 b of the outer cylinder 14. Further, the outer cylinder 14 has a friction coefficient between the outer peripheral surface 14 a of the outer cylinder 14 and the inner peripheral surface 24 b of the housing 7 based on the friction coefficient between the inner peripheral surface 16 b of the main body 16 of the bush 13 and the outer peripheral surface 6 a of the rack shaft 6. It is made of a material (for example, metal) that becomes larger.

  The holding hole 12 formed in the housing 7 includes a small diameter portion 24 and a large diameter portion 25 having a larger diameter than the small diameter portion 24. The axial length of the small diameter portion 24 is longer than the axial length of the outer cylinder 14, and the outer diameter of the small diameter portion 24 is substantially equal to the outer diameter of the outer cylinder 14. The length of the large diameter portion 25 in the axial direction is larger than the plate thickness of the annular flange 17, and the outer diameter of the large diameter portion 25 is larger than the outer diameter of the annular flange 17. Further, the housing 7 is formed with an engaging portion 26 having a diameter larger than that of the large diameter portion 25 on the outer side in the axial direction of the holding hole 12 (right side in FIG. 2). An outer peripheral surface of an annular stopper 27 through which the rack shaft 6 is inserted is engaged and fixed to the engaging portion 26 by press-fitting.

  The annular flange 17 of the bush 13 is accommodated in the large diameter portion 25 of the holding hole 12. The outer cylinder 14 is held by the small diameter portion 24 by fitting the outer peripheral surface 14 a of the outer cylinder 14 and the inner peripheral surface 24 b of the small diameter portion 24 of the holding hole 12. A predetermined gap w is provided between the inner peripheral surface 14 b of the outer cylinder 14 and the outer peripheral surface 16 a of the main body 16 of the bush 13, and a pair of annular grooves formed on the inner peripheral surface 14 b of the outer cylinder 14. 23a, 23b and a pair of annular grooves 18a, 18b formed on the outer peripheral surface 16a of the body 16 of the bush 13 are arranged so as to face each other. The pair of elastic members 15 are respectively accommodated between the annular grooves 18a and 23a and the annular grooves 18b and 23b facing each other in a state of being elastically deformed in the radial direction A1. Each elastic member 15 has an allowance for both the bush 13 and the outer cylinder 14. The bush 13 is held by the outer cylinder 14 via a pair of elastic members 15 housed between the annular grooves 18a and 23a and the annular grooves 18b and 23b.

  Thus, in the bearing device 11, the rack shaft 6 is supported by the bush 13 held in the holding hole 12 via the outer cylinder 14 and the pair of elastic members 15. The bush 13 is tightened in the radial direction A1 by a pair of elastic members 15 and elastically contracts in diameter. Due to the reduced diameter of the bush 13, the inner peripheral surface 16 b of the main body 16 of the bush 13 follows the outer peripheral surface 6 a of the rack shaft 6. The rack shaft 6 is elastically supported in the radial direction A1 by a bush 13 fastened by a pair of elastic members 15.

  As described above, according to this embodiment, the friction coefficient between the outer cylinder 14 and the outer peripheral surface 14 a of the outer cylinder 14 and the inner peripheral surface 24 b of the holding hole 12 of the housing 7 is the inner peripheral surface 16 b of the main body 16 of the bush 13. And the outer peripheral surface 6 a of the rack shaft 6. Thereby, when the rack shaft 6 moves in the axial direction Y1, it is possible to restrict the movement of the outer cylinder 14 together with the rack shaft 6 in the axial direction Y1. Therefore, it is possible to prevent the bearing device 11 from coming off the housing 7.

  Further, since the movement of the bush 13 in the axial length direction Y1 of the rack shaft 6 is restricted by using the outer cylinder 14 having the friction coefficient, the radial direction A1 of the elastic member 15 with respect to the outer cylinder 14 and the bush 13 is used. The tightening allowance can be adjusted as appropriate. Thereby, the fastening margin of the elastic member 15 can be adjusted appropriately, and the support rigidity of the rack shaft 6 and the favorable sliding characteristic of the axial length direction Y1 can be obtained.

  The present invention is not limited to the contents of the above embodiments, and various modifications can be made within the scope of the claims. For example, the outer cylinder 14 may be made of a synthetic resin. The friction coefficient is adjusted by forming irregularities on the outer peripheral surface 14 a of the outer cylinder 14, and the friction coefficient between the outer peripheral surface 14 a of the outer cylinder 14 and the inner peripheral surface 24 b of the holding hole 12 of the housing 7 is the inner diameter of the body 16 of the bush 13. You may make it become larger than the friction coefficient of the surrounding surface 16b and the outer peripheral surface 6a of the rack shaft 6. FIG.

  Alternatively, the outer diameter of the outer cylinder 14 may be made larger than the inner diameter of the small diameter part 24 of the holding hole 12 in a free state, and the outer cylinder 14 may be press-fitted into the small diameter part 24. Furthermore, a slit that extends from one end of the outer cylinder 14 to the other end and intersects the circumferential direction of the outer cylinder 14 may be formed in the outer cylinder 14. Thereby, the outer cylinder 14 inserted into the small diameter portion 24 of the holding hole 12 is expanded by the pair of elastic members 15, and the outer peripheral surface 14 a of the outer cylinder 14 is pressed against the inner peripheral surface 24 b of the small diameter portion 24. it can.

1 is a schematic view schematically showing a rack and pinion steering device according to an embodiment of the present invention. FIG. 2 is an enlarged partial cross-sectional view schematically showing the bearing device in FIG. 1 and its periphery. It is sectional drawing which shows schematically the bush of the bearing apparatus in a free state.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rack and pinion type steering device (steering device), 6 ... Rack shaft (shaft member, steered shaft), 7 ... Housing, 11 ... Bearing device, 12 ... Holding hole, 13 ... Bush (inner cylinder), 16a ... Outer circumferential surface (outer circumferential surface of inner cylinder), 14 ... Outer cylinder, 14a ... Outer circumferential surface (outer circumferential surface of outer cylinder), 14b ... Inner circumference Surface (inner peripheral surface of outer cylinder), 15 ... elastic member, 18a, 18b, 23a, 23b ... annular groove, 20 ... slit, 24b ... inner peripheral surface (inner peripheral surface of holding hole) ) W ... gap, A1 ... radial direction, X1 ... left and right direction, Y1 ... axial length direction, Z1 ... circumferential direction

Claims (2)

An inner cylinder that slidably supports the shaft member;
An outer cylinder surrounding the inner cylinder with a predetermined gap in the radial direction;
An annular elastic member interposed between the inner cylinder and the outer cylinder in an elastically compressed state in the radial direction,
The inner cylinder has a slit extending in a direction intersecting the circumferential direction and can be elastically reduced in diameter,
On the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder, annular grooves that accommodate the elastic members are formed opposite to each other,
The outer peripheral surface of the outer cylinder is fitted and held in the inner peripheral surface of the holding hole of the housing,
A bearing device, wherein a friction coefficient between an outer peripheral surface of the outer cylinder and an inner peripheral surface of the holding hole of the housing is larger than a friction coefficient between the inner peripheral surface of the inner cylinder and the outer peripheral surface of the shaft member. A steered shaft as a shaft member extending in the left-right direction of the vehicle, a bearing device according to claim 1 that slidably supports the steered shaft in an axial length direction, and a housing having a holding hole for holding the bearing device; A steering apparatus comprising:

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