JP2008273294A - Rack bar supporting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rack bar supporting device capable of suppressing generation of abnormal noise such as contact noise of a rack guide while maintaining high durability and reliability without any increase of the number of components, complicate structure or degradation of rigidity. <P>SOLUTION: The rack bar supporting device 20 comprises a rack guide 21 in which a base part 31 slidably assembled in a storage hole 14a of a rack guide housing part 14 and having a continuous outer circumferential wall surface 31a and a slidably contact part 32 having a slidably contact recess 32a with a rack bar 12 being slidably brought into contact therewith and a pair of discontinuous outer circumferential wall surfaces 32b, 32b are formed of a metallic material in an integrated structure, a first supporting member 22 which is provided on the outer circumferential wall surface 31a of the base part 31 and closely attached to an inner circumferential wall surface of the storage hole 14a to support the rack guide 21, and a pair of second supporting members 23, 23 provided on the outer circumferential wall surfaces 32b, 32b of the slidably contact part 32, and closely attached to the inner circumferential wall surface of the storage hole 14a to respectively support the rack guide 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rack bar support device for a vehicle rack and pinion type steering device.

  As this type of rack bar support device, the one shown in Patent Document 1 is known. As shown in FIG. 1 of Patent Document 1, in the rack bar support device, the rack guide 11 is fitted into the guide hole 7 a of the rack housing 7 and pressed against the rack bar 1 by the spring 5 and the adjusting screw 6. ing. The rack guide 11 is formed of a synthetic resin material. On the outer periphery of the end of the rack guide 11 on the side that comes into sliding contact with the rack bar 1, a protrusion 11b that protrudes radially outward from the outer peripheral surface 11a is formed. As a result, the gap between the outer periphery of the upper end of the rack guide 11 and the guide hole 7 a of the rack housing 7 is reduced.

Moreover, what is shown by patent document 2 is known as another type of rack bar support apparatus. As shown in FIG. 1-3 of Patent Document 2, in the rack bar support device, the auxiliary member 12 is placed in the groove portion 7d of the support yoke (rack guide) 7 and the outer peripheral surface of the support yoke 7 and the concave portion 7a. And are fitted so that they can selectively appear and disappear. With the support yoke 7 mounted in the support yoke housing hole 1a, the auxiliary member 12 protrudes into the gap S from the outer peripheral surface of the support yoke 7 and comes into contact with the inner peripheral surface of the support yoke housing hole 1a. Further, the O-ring 11 is interposed in a space surrounded by the support yoke 7, the inner peripheral surface of the support yoke housing hole 1 a and the yoke plug 9. This prevents the outer periphery of the end portion of the support yoke 7 on the rack shaft 6 side from hitting the inner peripheral surface of the support yoke housing hole 1a, so that the load is applied to the rack shaft 6 by operation of the steering wheel or vibration transmitted from the steering wheel. Therefore, it is possible to suppress the generation of a contact sound in which the support yoke 7 contacts the support yoke receiving hole 1a when acting on the support yoke 7.
Japanese Utility Model Publication No. 61-25275 JP 2002-321630 A

  In the rack bar support device described in Patent Document 1, the clearance between the outer periphery of the upper end portion of the rack guide 11 and the guide hole 7a of the rack housing 7 is reduced, so that the vibration transmitted from the steering wheel operation or the steering wheel. For example, when a load acts on the rack guide 11 from the rack bar 1, it is possible to prevent the rack guide 11 from coming into contact with the guide hole 7 a. However, since the rack guide 11 is made of a synthetic resin, it is affected by temperature changes and the like as compared with a metal guide, so that durability and reliability are lowered.

  Further, in the rack bar support device described in Patent Document 2, it is possible to suppress the generation of a contact sound that the support yoke 7 contacts the support yoke receiving hole 1a. There is a problem that at least the auxiliary member 12 is necessary and the structure becomes complicated. Further, there is a problem that the rigidity of the end portion of the support yoke 7 on the rack shaft 6 side is weakened by the amount of the auxiliary member 12.

  The present invention has been made to solve the above-described problems, and in the rack bar support device, durability and reliability can be maintained high without increasing the number of parts, making the structure complicated, and reducing the rigidity. However, it aims at suppressing generation | occurrence | production of unusual noises, such as a contact sound of a rack guide.

  In order to solve the above-mentioned problems, the structural features of the invention according to claim 1 are a housing in which a rack bar is slidably assembled in the rack axial direction, and a rack formed in the housing perpendicular to the rack bar. A pair of outer peripheries that are slidably assembled in the guide housing part and are formed in a columnar shape having an outer peripheral wall surface continuous in the circumferential direction and a sliding contact recess in which the rack bar is slidably contacted and discontinuous in the circumferential direction A rack guide in which a sliding contact portion having a wall surface is formed in an integral structure, and a first support that is fixed to the outer peripheral wall surface of the base portion of the rack guide and supports the rack guide in close contact with the inner peripheral wall surface of the rack guide housing portion A pair of second support members fixed to the outer peripheral wall surfaces of the member and the sliding contact portion of the rack guide and supporting the rack guide in close contact with the inner peripheral wall surface of the rack guide housing portion , Is that with.

  The structural feature of the invention according to claim 2 is that, in claim 1, the second support member is formed in a shape extending along the circumferential direction of the outer peripheral wall surface of the sliding contact portion.

  In the invention according to claim 1 configured as described above, the base portion and the sliding contact portion of the rack guide are rack guides via the first and second support members fixed to the outer peripheral wall surfaces of the base portion and the sliding contact portion. It is closely supported by the inner peripheral wall surface of the housing part. This prevents the outer peripheral wall surface of the rack bar end portion (sliding contact portion end portion) of the rack guide from coming into contact with the inner peripheral wall surface of the rack guide housing portion. When a load acts on the rack guide from the rack bar due to vibration or the like, it is possible to suppress the generation of a contact sound in which the rack guide contacts the inner peripheral wall surface of the rack guide housing portion. The rack guide includes a base portion formed in a column shape having an outer peripheral wall surface that is continuous in the circumferential direction, and a sliding contact portion that has a pair of outer peripheral wall surfaces that are discontinuous in the circumferential direction. Are formed in an integral structure. Thereby, high durability and high reliability of the rack guide can be realized, and the rigidity of the sliding contact portion of the rack guide can be maintained high. From the above, the rack bar support device generates abnormal noise such as contact sound of the rack guide while maintaining high durability and reliability without increasing the number of parts, complicating the structure, and reducing the rigidity. Can be suppressed.

  In the invention which concerns on Claim 2 comprised as mentioned above, in the invention which concerns on Claim 1, the 2nd supporting member is formed in the shape extended along the circumferential direction of the outer peripheral wall surface of a sliding contact part. . As a result, the sliding contact portion of the rack guide is reliably supported by the inner peripheral wall surface of the rack guide housing portion, so that the generation of contact noise can be more reliably suppressed.

  Hereinafter, an embodiment of a rack and pinion steering device for a vehicle to which a rack bar support device according to the present invention is applied will be described with reference to the drawings. 1 is a front view of a rack and pinion type steering device for a vehicle, FIG. 2 is a cross-sectional view of a rack bar support device, FIG. 3 is a cross-sectional view of the rack guide, and FIG. 4 is a side view of the rack guide. FIG. 5 is a plan view of the second support member.

  As shown in FIG. 1, the vehicle rack and pinion type steering device includes a housing 11, a rack bar 12, a tie rod 13, a rack guide housing part 14, a pinion shaft 15, and a rack bar support device 20.

  The housing 11 extends in the left-right direction (left-right direction in FIG. 1) of the vehicle (not shown) and is assembled to the vehicle. The rack bar 12 is assembled to the housing 11 so as to be slidable in the rack axial direction (left-right direction in FIG. 1). A rack 12a that meshes with the pinion 15a is formed on one side of the rack bar 12 (see FIG. 2).

  The base ends of the tie rods 13 are assembled to both ends of the rack bar 12, respectively. Each other end of the tie rod 13 is connected to each knuckle arm (not shown) of a steering wheel (for example, left and right front wheels). Thereby, since the movement of the rack bar 12 is transmitted to the knuckle arm via the tie rod 13, the vehicle can be steered according to the steering operation.

  The rack guide housing part 14 is formed in the housing 11 so as to be orthogonal to the rack bar 12. The rack guide housing part 14 is formed in a cylindrical shape and has a receiving hole 14a having a circular cross section. A rack guide 21 is slidably assembled in the accommodation hole 14a.

  As shown in FIG. 2, the pinion shaft 15 is rotatably mounted on the housing 11 via bearings 16 and 17. The pinion shaft 15 is connected to a steering shaft (not shown). A pinion 15 a is formed on the pinion shaft 15. The pinion 15a is formed with helical teeth and meshes with the rack 12a of the rack bar 12.

  The rack bar support device 20 includes a rack guide 21, first and second support members 22 and 23, an adjustment screw 24, and a spring 25.

  As shown in FIGS. 3 and 4, the rack guide 21 is slidably contacted with a base 31 formed in a columnar shape (cylindrical in the present embodiment) having an outer peripheral wall surface 31 a continuous in the circumferential direction and the rack bar 12. And a sliding contact portion 32 having a pair of outer peripheral wall surfaces 32b, 32b which are formed with a recess 32a and are discontinuous in the circumferential direction. The rack guide 21 is formed of a metal material (for example, aluminum material) in an integral structure. That is, the outer peripheral wall surface 31a of the base 31 of the rack guide 21 has a wall surface continuous along the circumferential direction. Moreover, since the outer peripheral wall surface of the sliding contact part 32 of the rack guide 21 is divided into a pair of outer peripheral wall surfaces 32b and 32b by the sliding contact recessed part 32a, it does not have the continuous wall surface along the circumferential direction.

  On the sliding contact recess 32 a of the rack guide 21, a sheet member 26 that is surface-treated with a material (for example, polyacetal resin) that improves sliding on the surface that contacts the rack bar 12 is assembled. The sheet member 26 is processed into a shape that matches the shape of the sliding contact recess 32a. The sheet member 26 is fixed to the rack guide 21 by press-fitting the convex portion 26 a of the sheet member 26 into the concave portion 21 b of the rack guide 21.

  The first support member 22 is fixed to the outer peripheral wall surface 31 a of the base portion 31 of the rack guide 21 and supports the rack guide 21 in close contact with the inner peripheral wall surface of the rack guide housing portion 14. The first support member 22 has an allowance for the accommodation hole 14 a of the rack guide housing portion 14. The first support member 22 is a member formed in an annular shape with an elastic material (for example, silicon material), and is, for example, an O-ring. The first support member 22 is attached to an annular groove 31 a 1 formed on the outer peripheral wall surface 31 a of the base 31.

  The pair of second support members 23 and 23 are fixed to the outer peripheral wall surfaces 32b and 32b of the sliding contact portion 32 of the rack guide 21, and support the rack guide 21 in close contact with the inner peripheral wall surface of the rack guide housing portion 14, respectively. Is. The pair of second support members 23, 23 has a tightening margin with respect to the accommodation hole 14 a of the rack guide housing portion 14. The second support member 23 is a slippery elastic material (for example, a fluororesin material (for example, polytetrafluoroethylene), a polyacetal resin material (for example, polyoxymethylene), a nylon resin material, a urethane resin material) or a metal material (for example, copper It is a member formed of an alloy. As shown in FIG. 5, the second support member 23 is formed in a (continuous) shape (for example, a crescent shape or an arc shape) extending along the circumferential direction of the outer peripheral wall surface 32 b of the sliding contact portion 32. . The total length is set shorter than the length of the continuous outer peripheral wall surface 32b.

  On the inner peripheral surface of the second support member 23, a plurality (three in the present embodiment) of fixing projections 23a for fixing are formed. The engaging convex portion 23a is fitted into an engaging concave portion 32b2 formed in a groove 32b1 formed in the outer peripheral wall surface 32b of the sliding contact portion 32 along the circumferential direction. The engaging convex portion 23a is set to have a diameter slightly larger than the outer diameter of the engaging concave portion 32b2, and a slit 23a1 is formed in the axial direction (see FIG. 6). Accordingly, the second support member 23 is mounted in the groove 32b1 by fitting the engagement convex portion 23a into the engagement concave portion 32b2. In addition, it is not necessary to provide the slit 23a1 in the engagement convex part 23a.

  The first and second support members 22 and 23 described above are provided as far as possible from the base 31 and the sliding contact portion 32 of the rack guide 21, that is, the first support member 22 can be provided at the left end of the base 31 in FIG. It is desirable to arrange the second support member 23 as close as possible to the right end of the sliding contact portion 32 in FIG. Thus, even if the rack bar 12 reciprocates in the axial direction of the pinion shaft 15 (vertical direction in FIG. 2), the reciprocating motion reliably suppresses the rack guide 21 from swinging in the vertical direction in FIG. can do.

  The adjustment screw 24 is disposed on the back side (base portion 31 side) of the rack guide 21 and closes the accommodation hole 14a of the rack guide housing portion 14. The adjusting screw 24 is screwed into the opening end of the accommodation hole 14a. The spring 25 is disposed between the rack guide 21 and the adjusting screw 24 in a compressed state, and is accommodated in the back recess 21 a of the rack guide 21. Thereby, the rack guide 21 presses the rack bar 12 against the pinion shaft 15 by the urging force of the spring 25. That is, the rack bar 12 is supported by the rack bar support device 20 so as to be slidable in the rack axis direction while being pressed toward the pinion 15a.

  As is clear from the above description, according to the present embodiment, the base portion 31 and the sliding contact portion 32 of the rack guide 21 are provided on the outer peripheral wall surface 31a of the base portion 31 and the respective outer peripheral wall surfaces 32b of the sliding contact portion 32, respectively. The first and second support members 22 and 23 are supported in close contact with the inner peripheral wall surface of the rack guide housing portion 14. In general, in a rack and pinion type steering device for a vehicle, a load caused by vibration transmitted from a steered wheel when traveling on a rough road or a load at the time of turning back when the steering wheel is turned off acts on the rack guide 21 from the rack bar 12. The rack guide 21 reciprocates as indicated by an arrow a along the axial direction of the rack guide 21 (left and right in FIG. 7), or along the axial direction of the pinion shaft 15 (up and down in FIG. 7). Then, as shown by an arrow b, a rocking motion (swing motion) is performed. Thus, even when a load acts on the rack guide 21 from the rack bar 12, according to the present embodiment, the outer peripheral wall surface 32b of the end of the rack guide 21 on the rack bar 12 side (end of the sliding contact portion 32) is Since the contact with the inner peripheral wall surface of the rack guide housing part 14 is prevented, it is possible to prevent the rack guide 21 from coming into contact with the inner peripheral wall surface of the rack guide housing part 14.

  Further, the second support members 23, 23 include a rack guide so as to include a portion that becomes a top portion when the outer peripheral wall surface 32b of the rack guide 21 collides with the rack guide housing portion 14 by the swinging motion (swinging motion) described above. 21 is extended in the circumferential direction (see FIG. 7), so that the swinging motion can be most effectively performed without providing a wide range of second support members 23, 23 on the outer peripheral surface of the rack guide 21. Can be suppressed.

  The rack guide 21 has a pair of outer peripheral wall surfaces 32b and 32b in which a base 31 formed in a column shape having a continuous outer peripheral wall surface 31a and a sliding contact recess 32a in which the rack bar 12 is in sliding contact are formed and are discontinuous. The sliding contact portion 32 is formed of a metal material into an integral structure. Thereby, high durability and high reliability of the rack guide 21 can be realized, and the rigidity of the sliding contact portion 32 of the rack guide 21 can be maintained high. From the above, in the rack bar support device 20, abnormal noise such as contact sound of the rack guide 21 is maintained while maintaining high durability and reliability without increasing the number of parts, complicating the structure, and reducing the rigidity. Can be suppressed.

  Moreover, since the rack bar 12 can be smoothly reciprocated by reducing the swinging motion of the rack guide 21, the friction characteristic between the rack 12a and the pinion 15a can be stabilized.

  The second support member 23 is formed in a shape extending (continuous) along the circumferential direction of the outer peripheral wall surface 32 b of the sliding contact portion 32. As a result, the sliding contact portion 32 of the rack guide 21 is reliably and closely supported by the inner peripheral wall surface of the rack guide housing portion 14, so that the generation of contact noise can be more reliably suppressed. In addition, for example, rather than using a support member extending in the axial direction, the movement of the rack guide 21 in the axial direction is suppressed, and a good steering feeling can be maintained.

  As the rack guide 21 reciprocates in the axial direction, stress due to contact resistance with the rack guide housing portion 14 acts on the second support members 23, 23. However, the second support members 23, 23 are located in the groove 32b1. Therefore, the durability of the second support members 23 and 23 can be enhanced without the stress concentrating on the engaging projections 23a of the second support members 23 and 23. Therefore, the number of the engaging protrusions 23a is not necessarily three as shown in FIG. 6, and may be one.

  Moreover, since the cross-sectional shape of the second support members 23 and 23 is substantially semicircular, the depth of the groove 32b1 can be made shallower than, for example, a circular shape, and the sliding contact portion 32 that is thinner than the base portion 31 can be formed. Even if the groove 32b1 is provided, the strength of the sliding contact portion 32 can be secured. The cross-sectional shape of the second support members 23, 23 can be a substantially triangular shape or a substantially trapezoidal shape whose bottom is located at the bottom of the groove 32b1.

  The first and second support members 22 and 23 are formed in a circular arc shape (see FIG. 6), and the first and second support members 22 and 23 are in line contact with the rack guide housing portion 14. This also contributes to not hindering the movement of the rack guide 21 in the axial direction.

  In the above-described embodiment, the second support member 23 is formed in a continuous (extending) shape along the circumferential direction of the outer peripheral wall surface 32b of the sliding contact portion 32, but is continuous (extended). For example, a plurality of pin-shaped members may be arranged at predetermined intervals. In this case, the second support member may be configured by a head and a shaft portion having a smaller diameter than the head.

  As shown in FIG. 8, the second support members 23, 23 are engaged with a head part 23 b 1 having a substantially semicircular cross section and an elastic deformation part 23 b 2 formed by cutting out a part of the head part 23 b 1. It can also be comprised with the convex part 23a. The elastic deformation portion 23b2 is assembled so as to be positioned between the head portion 23b1 and the bottom portion of the groove 32b1, and the engagement convex portion 23a and the engagement concave portion 32b2 are in a loosely fitted state.

  If the hardness of the head 23b1 is set so as not to be deformed by a relatively small load acting on the rack guide 21 during normal running, the head 23b1 is not elastically deformed with respect to the load, and the elastically deforming portion 23b2 The swinging motion of the rack guide 21 is elastically supported by the elastic force of the rack, and the vibration of the rack bar 12 is absorbed to maintain a good steering feeling.

  For a relatively large load acting on the rack guide 21 due to kickback when traveling on a rough road or the like, first, the swinging movement of the rack guide 21 is elastically supported by the elastic force of the elastic deformation portion 23b2, and the head After the portion 23b1 is pushed in until it comes into contact with the elastic deformation portion 23b2, the swinging movement of the rack guide 21 is elastically supported by elastic deformation of the head portion 23b1. In this manner, the rack guide 21 and the rack guide housing part 14 can be reliably prevented from contacting each other while maintaining a good steering feeling by supporting the swinging motion of the rack guide 21 in two stages.

  In the embodiment described above, two first support members 22 may be provided instead of one. In this case, it is desirable to provide at both ends of the base 31. Oscillation of the rack guide 21 along the rack axis direction can be more reliably suppressed.

  In the above-described embodiment, the second support member 23 is assembled to the sliding contact portion 32 by the engagement of the engagement convex portion 23a and the engagement concave portion 32b2. However, the second support member 23 is assembled by welding or adhesion. Also good.

1 is a front view of a vehicle rack and pinion steering device to which a rack bar support device according to the present invention is applied. It is sectional drawing of a rack bar support apparatus. It is sectional drawing along the axial direction of a rack guide. It is a side view of a rack guide. It is a top view of the 2nd support member. FIG. 6 is an end view taken along line 6-6. It is an expanded sectional view for demonstrating the effect | action of a rack bar support apparatus. It is sectional drawing along the axial direction which concerns on the modification of a 2nd support member.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Housing, 12 ... Rack bar, 13 ... Tie rod, 14 ... Rack guide housing part, 15 ... Pinion shaft, 15a ... Pinion, 16, 17 ... Bearing, 20 ... Rack bar support device, 21 ... Rack guide, 22 ... No. DESCRIPTION OF SYMBOLS 1 Support member, 23 ... 2nd support member, 23a ... Engagement convex part, 23b1 ... Head part, 23b2 ... Elastic deformation part, 24 ... Adjustment screw, 25 ... Spring, 26 ... Sheet member, 31 ... Base part, 31a ... Outer periphery Wall surface, 31a1 ... groove, 32 ... sliding contact portion, 32a ... sliding contact recess, 32b ... outer peripheral wall surface, 32b1 ... groove, 32b2 ... engagement recess.

Claims (2)

A housing in which the rack bar is slidably assembled in the rack axis direction;
A slidably assembled in a rack guide housing part formed perpendicular to the rack bar on the housing, and a base part formed in a column shape having an outer peripheral wall surface continuous in the circumferential direction, and the rack bar in sliding contact A rack guide in which a contact portion is formed and a sliding contact portion having a pair of outer peripheral wall surfaces discontinuous in the circumferential direction is formed in an integral structure;
A first support member fixed to an outer peripheral wall surface of the base portion of the rack guide and supporting the rack guide in close contact with an inner peripheral wall surface of the rack guide housing portion;
A pair of second support members fixed to each outer peripheral wall surface of the sliding contact portion of the rack guide and supporting the rack guide in close contact with an inner peripheral wall surface of the rack guide housing portion, Rack bar support device.   2. The rack bar support device according to claim 1, wherein the second support member is formed in a shape extending along a circumferential direction of an outer peripheral wall surface of the sliding contact portion.

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