JP2012030651A - Rack and pinion mechanism, and steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent collision of a rack guide and an accommodation housing, in a two-division structure of the rack guide which is accommodated in the accommodation housing.SOLUTION: The cylindrical accommodation housing 34 is formed integrally with a rack housing 26. The rack guide 32 is accommodated in an accommodation room 39 in the accommodation housing 34 so as to reciprocally move in an axis-line direction of the accommodation housing 34. The rack guide 32 includes: a cylindrical-shaped pedestal 21; a radial bearing 23 which is connected to the pedestal 21; and a guide section 24 which is connected to the radial bearing 23. The guide section 24 is pressed to a rack shaft 14 by a compression spring 36 so as to guide the rack shaft 14 in the direction of an axis line 140 of the rack shaft 14.

Description

  The present invention relates to a rack and pinion mechanism and a steering apparatus including the rack and pinion mechanism.

  In the rack and pinion mechanism in which the pinion teeth of the pinion shaft and the rack teeth of the rack shaft are meshed, the rotation of the pinion shaft is converted into the reciprocating motion of the rack shaft. The rack and pinion mechanism is used in a steering device for a vehicle as disclosed in Patent Documents 1, 2, and 3, for example. The rotation of the pinion shaft by the steering operation is converted into the reciprocating motion of the rack shaft, and thereby the steering angle of the steered wheels is changed.

  In the rack and pinion mechanism disclosed in Patent Document 2, the rack shaft is supported by a rack guide pressed by the spring force of the spring so as to be capable of reciprocating in the axial direction of the rack shaft. The rack guide is fitted in a cylindrical portion (accommodating housing) integrally formed with the rack housing that accommodates the rack shaft so as to be reciprocally movable, and the spring biases the rack guide toward the rack shaft. It is accommodated in the cylinder part.

  The rack guide is movable only in the direction in which it is in contact with or away from the rack shaft. For this reason, if the rack shaft is tilted due to the movement of the rack shaft accompanying steering operation or the vibration caused by running of the vehicle, the rack guide will come into contact with the rack shaft, causing abnormal noise, or the rack shaft or rack guide may be damaged. Or wear out.

  In the apparatus disclosed in Patent Document 1, a rack guide provided between a screw member screwed into the cylindrical portion and a rack shaft is configured to be tiltable with respect to the screw member. With this tiltable configuration, even if the rack shaft is tilted, the rack guide follows the tilt of the rack shaft, so that the rack guide does not hit the rack shaft.

  In the apparatus disclosed in Patent Document 3, the rack guide has a two-part structure of a rack side rack guide and a spring side rack guide, and a sphere or a pin is interposed between the rack side rack guide and the spring side rack guide. ing. The rack-side rack guide can be tilted with respect to the axis of the spring-side rack guide by the presence of a sphere or a pin. With this tiltable configuration, even if the rack shaft is tilted, the rack side rack guide follows the tilt of the rack shaft, so that the rack side rack guide does not hit the rack shaft.

Japanese Utility Model Publication No. 61-23969 JP-A-2005-41251 JP 2010-18166 A

However, in any of the devices of Patent Documents 1 and 3, the tilting rack guide collides with the inner peripheral wall surface of the cylindrical portion (accommodating housing), and abnormal noise is generated.
An object of the present invention is to prevent the rack guide and the housing from colliding with each other when the rack guide housed in the housing is divided into two.

  According to the first to sixth aspects of the present invention, a pinion shaft having pinion teeth, a rack shaft having rack teeth meshing with the pinion teeth, and the rack shaft so that the rack teeth and the pinion teeth mesh with each other. A rack guide to be pressed, and the rack guide is housed in a housing chamber in a housing, and the rack guide is capable of guiding the rack shaft in an axial direction of the rack shaft, and the rack guide is capable of being guided by a pressing unit. A rack and pinion mechanism that is pressed against a shaft is an object. In the first aspect of the invention, the rack guide is connected to the pedestal accommodated in the accommodation chamber, a radial bearing connected to the pedestal, and the radial bearing. A guide part, and the guide part is capable of guiding the rack shaft in an axial direction of the rack shaft so as to be able to guide the rack shaft. It is pressed against the rack shaft by the step.

  The guide portion connected to the pedestal via the radial bearing is rotatable about the rotation axis of the radial bearing and hardly tilts with respect to the pedestal. Therefore, if an appropriate clearance is provided between the outer periphery of the guide portion and the chamber forming wall surface of the storage chamber, the outer periphery of the guide portion and the chamber forming wall surface of the storage chamber will not collide.

  In a preferred example, the guide part includes a joint part joined to the rack shaft and a base end part connected to the joint part, and the base end part has a circumferential outer peripheral surface. The radial bearing is fitted to the base end so as to contact the outer peripheral surface.

The base end portion of the guide portion can rotate around the rotation axis of the radial bearing inside the radial bearing.
In a preferred example, the pedestal has a cylindrical portion, and the radial bearing is fitted to the cylindrical portion so as to contact the inner peripheral surface of the cylindrical portion.

The base end portion of the guide portion is rotatable around the rotation axis of the radial bearing inside the cylindrical portion.
In a preferred example, the pedestal includes a support shaft, and the guide portion includes a joint portion joined to the rack shaft, and a base end portion connected to the joint portion, and the base end portion. Has a cylindrical portion, and the radial bearing is fitted to the support shaft so as to be in contact with the inner peripheral surface of the cylindrical portion of the base end portion.

The cylindrical portion of the guide portion is rotatable around the rotational axis of the radial bearing outside the radial bearing.
In a preferred example, the pressing means is a compression spring that contacts the pedestal and biases the pedestal toward the rack shaft.

  In a preferred example, the base end portion has an end wall facing the pedestal, the pedestal has a through hole facing the end wall, and the pressing means includes the through hole. And a compression spring that urges the base end portion toward the rack shaft in contact with the end wall.

The compression spring urges the guide portion directly toward the rack shaft in contact with the guide portion.
A steering device according to a seventh aspect of the invention includes the rack and pinion mechanism according to any one of the first to sixth aspects.

  The steering apparatus of the present invention is an apparatus that has improved quietness by preventing the generation of abnormal noise caused by the collision between the rack guide and the housing.

  The present invention has an excellent effect that it is possible to prevent the rack guide and the housing from colliding with each other when the rack guide housed in the housing is divided into two.

The schematic block diagram of the steering device which shows 1st Embodiment. (A) is sectional drawing which shows schematic structure of a rack and pinion mechanism. (B) is a partial expanded sectional view. The partial expanded sectional view which shows 2nd Embodiment. The partial expanded sectional view which shows 3rd Embodiment. The partial expanded sectional view which shows 4th Embodiment. The partial expanded sectional view which shows 5th Embodiment.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, a steering shaft 12 to which a steering 11 is fixed is connected to a rack shaft 14 via a rack and pinion mechanism 13. The steering shaft 12 is configured by connecting a column shaft 15, an intermediate shaft 16 and a pinion shaft 17. The rotation of the steering shaft 12 accompanying the steering operation is converted into a reciprocating linear motion of the rack shaft 14 via the rack and pinion mechanism 13. The reciprocating linear motion of the rack shaft 14 accompanying the rotation of the steering shaft 12 is transmitted to a knuckle (not shown) via tie rods 18 connected to both ends of the rack shaft 14. Thereby, the rudder angle of the steered wheels 19, that is, the traveling direction of the vehicle is changed.

  A motor 20 that applies an assist force for assisting the steering operation is coupled to the column shaft 15 via a speed reduction mechanism 25. The rotation of the motor 20 is decelerated by the speed reduction mechanism 25 and transmitted to the column shaft 15. That is, the motor torque is applied to the steering system as an assist force.

  As shown in FIG. 2A, the rack and pinion mechanism 13 includes a rack shaft 14, a pinion shaft 17, and a rack housing 26 that houses the rack shaft 14. The rack housing 26 is integrally formed with a cylindrical portion 27 extending in a direction substantially orthogonal to the axis 140 of the rack shaft 14 (substantially up and down in the figure). The pinion shaft 17 is rotatably supported by the cylindrical portion 27 via bearings 28 and 29 in the cylindrical portion 27.

  An upper end 171 of the pinion shaft 17 is connected to the intermediate shaft 16 (see FIG. 1) in a state of protruding from the opening end 271 of the cylindrical portion 27. Pinion teeth 31 are formed on the pinion shaft 17 in the rack housing 26, and rack teeth 30 are formed on the rack shaft 14. The pinion teeth 31 mesh with the rack teeth 30.

  A cylindrical housing housing 34 is integrally formed with the rack housing 26 so as to extend in a direction substantially orthogonal to the cylindrical portion 27. The accommodation chamber 39 in the accommodation housing 34 has an outer opening 391 that opens to the outside of the rack housing 26 and an inner opening 392 that opens to the inside of the rack housing 26. The inner opening 392 opens toward the pinion teeth 31.

  A screw cap 35 is screwed into the outer opening 391 of the storage chamber 39. A rack guide 32 is housed in the housing chamber 39 whose outer opening 391 is closed by the screw cap 35 so as to be capable of reciprocating in the axial direction of the tubular housing housing 34.

  As shown in FIG. 2B, the rack guide 32 includes a cylindrical pedestal 21, a radial bearing 23 connected to the pedestal 21, and a guide portion 24 connected to the radial bearing 23. The rack guide 32 has a two-part structure in which the base 21 and the guide portion 24 are connected by a radial bearing 23.

  The radial bearing 23 of the present embodiment is a needle bearing. The radial bearing 23 includes an outer ring 231, a needle 232, and a needle holder (not shown). A partition wall 213 is formed in a cylinder of the cylindrical pedestal 21, and a cylindrical portion 214 is formed in a portion of the pedestal 21 closer to the rack shaft 14 than the partition wall 213. The outer ring 231 of the radial bearing 23 is fitted and fixed inside the tube portion 214 so as to be joined to the inner peripheral surface 215 of the tube portion 214.

  The outer diameter of the columnar pedestal 21 is smaller than the inner diameter of the cylindrical housing housing 34, and there is a gap between the outer peripheral surface of the pedestal 21 and the inner peripheral surface 341 of the housing housing 34. On the outer peripheral surface of the cylindrical pedestal 21, annular grooves 211 and 212 are formed so as to go around the outer peripheral surface of the pedestal 21, and annular elastic rings 37 and 38 are fitted in the annular grooves 211 and 212. . The elastic rings 37 and 38 are in contact with the inner peripheral surface 341 of the cylindrical housing housing 34, and when the pedestal 21 reciprocates in the axial direction of the housing housing 34, the elastic rings 37 and 38 are in the inner periphery of the housing housing 34. It is in sliding contact with the surface 341.

  The guide portion 24 is a concave portion formed on the side facing the back surface 141 opposite to the rack teeth 30 of the rack shaft 14 and the cylindrical base end portion 241 to be rolled by the needle 232 of the radial bearing 23. 242. The base end portion 241 is fitted inside the radial bearing 23. That is, the radial bearing 23 is fitted to the base end portion 241 so that the needle 232 is in contact with the outer peripheral surface 243 of the circumferential surface shape of the base end portion 241. The guide portion 24 is rotatable with respect to the cylindrical pedestal 21 around the central axis 210 of the pedestal 21.

  The sheet member 33 is fixed to the concave portion 242. The sheet member 33 has a sliding contact surface 331 that matches the shape (circumferential surface) of the back surface 141 of the rack shaft 14, and the back surface 141 is joined to the sliding contact surface 331. The concave portion 242 and the sheet member 33 constitute a joint portion that is joined to the rack shaft 14.

The pedestal 21 and the guide portion 24 are made of, for example, an aluminum alloy, and the sheet member 33 is formed by, for example, applying a resin coating to a copper alloy.
A compression spring 36 as a pressing means is interposed between the partition wall 213 of the base 21 and the screw cap 35. The compression spring 36 biases the base 21 toward the rack shaft 14. The spring force of the compression spring 36 acting on the base 21 urges the guide portion 24 toward the rack shaft 14 via the radial bearing 23, and the sliding contact surface 331 of the seat member 33 pushes against the back surface 141 of the rack shaft 14. Touched. The spring force of the compression spring 36 acting on the guide portion 24 presses the rack teeth 30 of the rack shaft 14 against the pinion teeth 31.

  The rack shaft 14 is supported by a rack guide 32 provided in the housing housing 34 and a slide bearing (not shown) provided in the rack housing 26 so as to be able to reciprocate along the direction of the axis 140 of the rack shaft 14. .

In the first embodiment, the following effects can be obtained.
(1) For example, as shown in FIG. 2B, the load F from the rack shaft 14 to the rack guide 32 due to the movement of the rack shaft 14 in the direction of the axis 140 or the inclination of the rack shaft 14 is A load F1 in the direction of the central axis 210 and a load F2 acting on the guide portion 24 in a direction parallel to a direction line orthogonal to the central axis 210 of the pedestal 21 are divided. The load F1 is absorbed by the reduction of the compression spring 36. On the other hand, in most cases, the load F2 acts on a position off the center axis 210 of the pedestal 21. The action of the load F2 on the position off the center axis 210 of the pedestal 21 causes the guide portion 24 to Acts as a moment to rotate about the central axis 210.

  The guide portion 24 connected to the pedestal 21 via the radial bearing 23 is rotatable about the rotation axis of the radial bearing 23, that is, the center axis 210 of the pedestal 21, and the guide portion 24 is relative to the pedestal 21. There is no tilting. Therefore, the action of the load F <b> 2 at a position deviated from the central axis 210 of the pedestal 21 rotates the guide portion 24 around the rotational axis of the radial bearing 23. As a result, the guide portion 24 and the pedestal 21 are not tilted by the action of the load F2 to a position deviated from the central axis 210, and the guide portion 24 or the pedestal 21 does not collide with the chamber forming wall surface of the storage chamber 39. .

  (2) When the acting direction of the load F2 on the guide portion 24 is substantially orthogonal to the central axis 210 of the pedestal 21, the load F2 tilts the guide portion 24 together with the pedestal 21 with respect to the central axis 210 of the pedestal 21. In some cases. The pedestal 21 connected to the guide portion 24 via the radial bearing 23 is also tilted in the same manner as the guide portion 24. The elastic rings 37 and 38 fitted in the annular grooves 211 and 212 are elastically deformed to absorb the inclination of the base 21. If the elastic characteristics of the elastic rings 37 and 38 and the gap between the outer peripheral surface of the guide portion 24 and the pedestal 21 and the inner peripheral surface of the accommodating housing 34 are appropriately set, the outer peripheral edges of the guide portion 24 and the pedestal 21 are reduced. It is possible to prevent the housing housing 34 from colliding with the inner peripheral surface 341. The presence of the elastic rings 37 and 38 contributes to the prevention of abnormal noise caused by the outer peripheral edge of the base 21 colliding with the inner peripheral surface 341 of the housing housing 34.

Next, a second embodiment of FIG. 3 will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.
The compression spring 36 is in contact with the end wall 40 of the base 21 </ b> A and biases the base 21 </ b> A toward the rack shaft 14. A support shaft 401 projects from the end wall 40 of the pedestal 21A toward the rack shaft 14 in the direction of the central axis 210 of the pedestal 21A, and a radial bearing 41 is fitted and fixed to the outer peripheral surface of the support shaft 401. Has been. The radial bearing 41 is a radial bearing including an inner ring 411, a ball 412, and an outer ring 413 that are fitted to the outer peripheral surface of the support shaft 401.

  A cylindrical portion 244 projects from the base end portion 241A of the guide portion 24A toward the pedestal 21A, and an outer ring 413 of the radial bearing 41 is fitted and fixed to the cylindrical portion 244. That is, the guide portion 24A is rotatably supported by the base 21A via the radial bearing 41.

In the second embodiment, the same effect as in the first embodiment can be obtained.
Next, a third embodiment of FIG. 4 will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.

  The position of the cylindrical pedestal 21 </ b> B is regulated by a circlip 43 provided on the inner peripheral surface 341 of the housing 34. One end of the compression spring 36 is in contact with the end wall 245 of the base end portion 241 of the guide portion 24 through the cylinder 216 (through hole) of the cylindrical pedestal 21 </ b> B. It is energizing towards. A ring-shaped plain bearing 44 that is a radial bearing is fitted to the outer periphery of the base end portion 241 of the guide portion 24. The slide bearing 44 is made of synthetic resin. The slide bearing 44 is fitted into the cylinder of the base 21B so as to be slidable and rotatable with respect to the inner peripheral surface of the base 21B. The position of the slide bearing 44 is regulated by a circlip 45 provided on the outer peripheral surface of the base end portion 241. The circlip 45 prevents the sliding bearing 44 from dropping from the base end portion 241. The guide part 24 is movable in the direction of the central axis 210 of the base 21B. Movement of the guide portion 24 in the direction of the central axis 210 of the base 21B directly expands and contracts the compression spring 36.

  A thrust bearing 42 is provided on the end surface 351 of the screw cap 35 facing the end wall 245 of the base end portion 241 of the guide portion 24, and the other end of the compression spring 36 is in contact with the thrust bearing 42. The compression spring 36 can rotate integrally with the guide portion 24.

  In the third embodiment, since the base 21 </ b> B does not move in the direction of the central axis 210, the elastic rings 37 and 38 that are in contact with the inner peripheral surface 341 of the storage housing 34 slide with respect to the inner peripheral surface 341 of the storage housing 34. There is nothing. The configuration in which the elastic rings 37 and 38 are not slid prevents the elastic rings 37 and 38 from being worn and extends the life of the elastic rings 37 and 38.

  In this embodiment, the sliding bearing 44 is fixed to the inner peripheral surface of the pedestal 21B by an appropriate method, and the base end portion 241 of the guide portion 24 is slidable with respect to the inner peripheral surface of the sliding bearing 44. You may make it rotate.

Next, a fourth embodiment of FIG. 5 will be described. The same reference numerals are used for the same components as those in the second embodiment, and detailed description thereof is omitted.
A cylindrical support shaft 402 projects from the end wall 40 of the pedestal 21A toward the rack shaft 14 in the direction of the central axis 210 of the pedestal 21A, and a radial bearing 41 is fitted on the outer peripheral surface of the support shaft 402. And fixed. The compression spring 36 passes through the cylinder 403 (through hole) of the cylindrical support shaft 402, and one end of the compression spring 36 is in contact with the end wall 245 of the base end portion 241 of the guide portion 24A. The other end of the compression spring 36 is in contact with the end surface 351 of the screw cap 35. Movement of the guide portion 24A in the direction of the central axis 210 of the pedestal 21A directly expands and contracts the compression spring 36.

In the fourth embodiment, the same effect as in the first embodiment can be obtained.
Next, a fifth embodiment of FIG. 6 will be described. The same components as those in the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  A cylindrical pedestal 21 </ b> C is integrally formed on the screw cap 35, and the elastic rings 37 and 38 in the first to fourth embodiments are not provided. Since the screw cap 35 screwed into the storage chamber 39 does not tilt, the outer peripheral edge of the pedestal 21 </ b> C is reliably prevented from colliding with the inner peripheral surface 341 of the storage housing 34.

In the present invention, the following embodiments are also possible.
In the first and third embodiments, a sliding bearing may be used as the radial bearing.
-The sliding bearing may be made of metal.

-You may apply this invention to the rack and pinion mechanism used for apparatuses other than a steering apparatus.
The technical idea that can be grasped from the embodiment described above will be described below.

  (A) The rack and pinion mechanism according to any one of claims 1 to 6, wherein an annular groove is formed on an outer peripheral surface of the pedestal, and an elastic ring is fitted into the annular groove.

  13: Rack and pinion mechanism. 14 ... Rack shaft. 140 ... axis. 17 ... pinion shaft. 21, 21A, 21B, 21C ... pedestal. 214 ... A cylinder part. 215 ... Inner peripheral surface. 216, 403... In a cylinder which is a through hole. 23, 41 ... Radial bearings. 24, 24A ... Guide portion. 241, 241A: Base end portion. 242... Concave portion constituting the joint portion. 243 ... Outer peripheral surface. 245 ... End wall. 30 ... Rack teeth. 31 ... pinion teeth. 32 ... Rack guide. 33 ... A sheet member constituting the joint. 34. Housing housing. 36: A compression spring as a pressing means. 39: Containment room. 40: End wall. 44: A sliding bearing which is a radial bearing.

Claims (7)

The rack guide, comprising: a pinion shaft having pinion teeth; a rack shaft having rack teeth meshing with the pinion teeth; and a rack guide pressed against the rack shaft so that the rack teeth and the pinion teeth mesh with each other. Is stored in a storage chamber in a storage housing, and the rack guide is capable of guiding the rack shaft in the axial direction of the rack shaft, and is a rack and pinion mechanism that is pressed against the rack shaft by a pressing unit.
The rack guide includes a pedestal accommodated in the accommodation chamber, a radial bearing coupled to the pedestal, and a guide portion coupled to the radial bearing,
The guide portion is a rack and pinion mechanism that is pressed against the rack shaft by the pressing means so that the rack shaft can be guided in the axial direction of the rack shaft.   The guide part includes a joint part joined to the rack shaft and a base end part connected to the joint part, and the base end part has a circumferential outer peripheral surface, and the radial The rack and pinion mechanism according to claim 1, wherein the bearing is fitted to the base end so as to contact the outer peripheral surface.   The rack and pinion mechanism according to claim 2, wherein the pedestal has a cylindrical portion, and the radial bearing is fitted to the cylindrical portion so as to be in contact with an inner peripheral surface of the cylindrical portion.   The pedestal includes a support shaft, and the guide portion includes a joint portion joined to the rack shaft and a base end portion connected to the joint portion, and the base end portion includes a cylindrical portion. The rack-and-pinion mechanism according to claim 1, wherein the radial bearing is fitted to the support shaft so as to be in contact with an inner peripheral surface of the cylindrical portion of the base end portion.   The rack and pinion mechanism according to any one of claims 1 to 4, wherein the pressing means is a compression spring that comes into contact with the pedestal and biases the pedestal toward the rack shaft.   The base end portion has an end wall facing the pedestal, the pedestal has a through hole facing the end wall, and the pressing means passes through the through hole, and The rack and pinion mechanism according to any one of claims 2 to 4, wherein the rack and pinion mechanism is a compression spring that urges the base end portion toward the rack shaft in contact with an end wall.   A steering apparatus comprising the rack and pinion mechanism according to any one of claims 1 to 6.

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