JP2007245828A - Rack receiver seat, support yoke and steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rack receiver seat capable of smoothly moving and guiding a rack shaft for a long period of time by preventing increase of sliding resistance caused by loss of a lubricant, a support yoke furnished with this rack receiver seat and a rack pinion type steering system capable of reducing deterioration of steering feeling due to increase of the sliding resistance of the rack shaft. <P>SOLUTION: Recessed grooves 42 for introduction of the lubricant extending toward the inside in the axial direction from each of both side edges in the axial direction of the rack shaft are formed on a receiver surface 41 of the rack receiver seat 4 to slide on a peripheral surface of the rack shaft through the lubricant. It is desirable that the recessed grooves 42 are extended toward the inside at least from one of the both side edges. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motion conversion mechanism that converts rotation of a pinion into movement in the axial direction of the rack shaft, or a motion conversion mechanism that converts movement in the axial direction of the rack shaft into rotation of the pinion. The present invention relates to a rack receiving sheet that is used by being attached to a support yoke that moves and guides a rack shaft while applying a preload to a meshing portion thereof, and a support yoke provided with the rack receiving sheet, and a rack pinion using the support yoke The present invention relates to a steering device of the type.

  A rack-and-pinion type steering device that is widely used as a steering device for a vehicle is the movement of the pinion in accordance with the operation of a steering member such as a steering wheel in the axial direction of the rack shaft that meshes with the pinion. The left and right wheels connected to both ends of the rack shaft via tie rods are pushed and pulled to steer these wheels.

  In such a rack and pinion type steering device, in order to perform steering in both the left and right directions with high accuracy without delay, an appropriate preload is applied to the meshing portion of the rack shaft and the pinion, and both are substantially It is important to mesh without backlash, and for this reason, conventionally, the rack shaft is pressed from the opposite side of the meshing portion with the pinion, and the rack shaft is moved and guided in the axial direction while preloading the meshing portion. A yoke is used.

The support yoke includes a rack receiving sheet attached to the pressing surface of the rack shaft (see, for example, Patent Documents 1 and 2). This rack receiving sheet is, for example, a two-layer structure in which a coating film made of a resin such as PTFE (polyethylene terephthalate) is formed on the surface of a metal substrate, and both the high strength of the metal substrate and the sliding property of the resin material are combined. The structure is configured such that the surface on which the coating film is formed is brought into sliding contact with the peripheral surface of the rack shaft via an appropriate lubricant such as grease so that the rack shaft can be smoothly moved and guided under the application of the preload. Has been.
JP 2002-337702 A JP 2002-370654 A

  However, the lubricant between the rack receiving sheet and the rack shaft is generally supplied at the time of assembly. The lubricant moves to the peripheral surface of the rack shaft by repeated movement of the rack shaft over a predetermined stroke. There is a problem that the resistance reduction effect due to this lubricant is lost early, and the driver who operates the steering member feels that the steering feeling is deteriorated due to an increase in sliding resistance. .

  In order to cope with this problem, in Patent Document 2, a rack receiving sheet configured to form a large number of recesses on the sliding contact surface with the rack shaft and hold the lubricant in these recesses is used. The lubricant is fastened to the sliding part. However, even in this configuration, it is inevitable that the lubricant held in the recess adheres to the peripheral surface of the rack shaft and is taken out to both sides of the sliding contact portion of the rack receiving sheet as the rack shaft moves. Since the lubricant once taken out does not return to the sliding contact portion between the rack shaft and the rack receiving sheet, only the effect of delaying the increase in sliding resistance is obtained, and the rack shaft is smoothed over a long period of time. It is difficult to guide to move.

  The rack-and-pinion type motion conversion mechanism is not limited to the rack-and-pinion type steering device described above, but is used in a wide range of technical fields to convert rotational motion into linear motion. Smooth movement guidance is a necessary issue throughout these technical fields.

  The present invention has been made in view of such circumstances, and can prevent an increase in sliding resistance due to loss of lubricant, and a rack receiving sheet capable of smoothly moving and guiding a rack shaft over a long period of time. And a support yoke provided with the rack receiving sheet, and further provided with the support yoke, a rack and pinion type steering device capable of reducing deterioration in steering feeling due to an increase in sliding resistance of the rack shaft. For the purpose.

  The rack receiving sheet according to the first aspect of the present invention presses a rack shaft, in which rack teeth meshing with a pinion are arranged in parallel in the axial direction, from the opposite side of the meshing portion with the pinion, and preloads the meshing portion. In addition, in a rack receiving sheet that is mounted on a support yoke that moves and guides the rack shaft in the axial direction and is in sliding contact with the peripheral surface of the rack shaft via a lubricant, both side edges in the axial direction of the rack shaft And a lubricant introduction groove extending inward in the axial length direction from at least one of the above.

  A rack receiving sheet according to a second aspect of the present invention is characterized in that the introduction groove according to the first aspect extends from the respective side edges toward the inside in the axial length direction.

  The rack receiving sheet according to a third aspect of the present invention is characterized in that the introduction groove in the first or second aspect is formed by reducing the depth from the outer side toward the inner side in the axial length direction. .

  A rack receiving sheet according to a fourth aspect of the present invention is characterized in that the introduction groove according to any one of the first to third aspects is formed by reducing the width from the outside toward the inside in the axial length direction. And

  A rack receiving sheet according to a fifth aspect of the present invention is characterized in that a plurality of introduction grooves according to any one of the first to fourth aspects are arranged side by side in the circumferential direction of the rack shaft.

  The rack receiving sheet according to a sixth aspect of the present invention is characterized in that the introduction groove according to any one of the second to fifth aspects is formed by different circumferential positions on both side edges. To do.

  The rack receiving sheet according to the seventh invention of the present invention is characterized in that the introduction groove according to any one of the second to fifth inventions is formed by aligning circumferential positions of the both side edges. To do.

  In the support yoke according to the eighth aspect of the present invention, the rack shaft in which the rack teeth meshing with the pinion are juxtaposed in the axial length direction is pressed from the opposite side of the meshing portion with the pinion to preload the meshing portion. In addition, in the support yoke for moving and guiding the rack shaft in the axial length direction, the rack receiving sheet according to any one of the first to seventh inventions is mounted on a pressing surface to the rack shaft. And

  Furthermore, the steering apparatus according to the ninth aspect of the present invention is a rack for performing steering by converting the rotation of the pinion shaft in accordance with the operation of the steering wheel into the movement in the axial direction of the rack shaft meshing with the pinion shaft. In the pinion type steering apparatus, the support yoke according to the eighth aspect of the present invention is configured to press the rack shaft from the opposite side of the meshing portion with the pinion shaft and move and guide the rack shaft while applying a preload to the meshing portion. It is characterized by providing.

  In the rack receiving sheet according to the first aspect of the present invention, the introduction groove extending inward in the axial direction from at least one of both side edges in the axial direction of the rack shaft is attached to the peripheral surface of the rack shaft. The lubricant is received, guided in the extending direction, and returned to the sliding contact portion between the rack shaft and the rack receiving sheet, effectively preventing deterioration of the lubricity due to loss of the lubricant and under low sliding resistance The rack shaft can be smoothly moved and guided over a long period of time.

  In the rack receiving sheet according to the second aspect of the present invention, when the rack shaft is moved in both directions, the sliding contact portion between the rack shaft and the rack receiving sheet is caused by the action of the introduction groove extending inward from the both side edges. Since the lubricant is guided, more lubricant can be supplied to the sliding contact portion, and deterioration of lubricity due to loss of the lubricant can be more effectively prevented.

  Further, in the rack receiving sheets according to the third and fourth inventions, the lubricant introduction grooves are formed as grooves that reduce the depth and width inward from both side edges in the axial length direction of the rack receiving sheets. The lubricant received from the side edge in which the introduction groove is formed is reliably guided inward by the wedge effect, spreads well to the sliding contact portion between the rack shaft and the rack receiving sheet, and the rack shaft over a long period of time. Can be smoothly guided.

  In the rack receiving sheet according to the fifth aspect of the present invention, since a plurality of the introduction grooves having the above-described action are arranged in the circumferential direction of the rack shaft, most of the lubricant adhering to the peripheral surface of the rack shaft is removed Returning to the sliding contact portion between the rack and the rack receiving sheet, it is possible to more reliably prevent a decrease in lubricity due to the loss of the lubricant.

  Further, in the rack receiving sheet according to the sixth aspect of the invention, since the positions of the introduction grooves on the both side edges of the rack receiving sheet which are the receiving ends of the lubricant are varied in the circumferential direction, the lubricant adhering to the peripheral surface of the rack shaft In the rack receiving sheet according to the seventh aspect of the present invention, the positions of the introduction grooves at the both side edges of the rack receiving sheet serving as the receiving end of the lubricant are aligned in the circumferential direction. The lubricant adhering to the peripheral surface of the rack shaft can be reintroduced from both sides under the same conditions, and in any case, the rack shaft can be smoothly moved and guided over a long period of time.

  In addition, since the support yoke according to the eighth aspect of the present invention is provided with the rack receiving sheet that performs the above-described operation, the sliding resistance of the rack shaft due to the loss of the lubricant is prevented from increasing, and the movement guide is smoothly provided over a long period of time. It becomes possible to do.

  Furthermore, in the steering apparatus according to the ninth aspect of the invention, since the support yoke including the rack receiving sheet that performs the above-described function is provided for the movement guide of the rack shaft that moves in the axial direction for steering, the sliding resistance The present invention has excellent effects such as preventing deterioration of the steering feeling due to the increase in the steering angle and obtaining a good steering feeling over a long period of time.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a longitudinal sectional view showing a configuration of a main part of a rack and pinion type steering apparatus as an application example of a rack receiving sheet according to the present invention.

  In the figure, reference numeral 10 denotes a pinion housing, and the pinion shaft 1 is supported inside the pinion housing 10 so as to be rotatable coaxially. The pinion shaft 1 includes a pinion 11 integrally formed by expanding the lower half of the diameter, and is supported by a pair of angular ball bearings 12 and 13 positioned on both upper and lower sides of the pinion 11. Further, the upper end portion of the pinion shaft 1 protruding outside the pinion housing 10 is connected to a steering wheel 14 schematically shown in the drawing. Thus, the pinion shaft 1 rotates inside the pinion housing 10 in accordance with the rotation operation of the steering wheel 14 for steering.

  A cylindrical rack housing 20 is provided on one side of the lower half of the pinion housing 10 so as to cross the shaft center, and the rack housing 20 includes a rack that is movable in the axial direction. The shaft 2 is supported. On the peripheral surface of the rack shaft 2, rack teeth 21 are formed over an appropriate length on the side facing the communication portion between the pinion housing 10 and the rack housing 20, and the rack teeth 21 are meshed with the pinion 11. Further, both ends of the rack shaft 2 project from both sides of the rack housing 20 and are connected to left and right wheels (not shown), respectively, and these wheels are moved according to the movement of the rack shaft 2 in the rack housing 20. It is designed to be steered.

  In addition, a guide housing 30 that is substantially orthogonal to both the housings 10 and 20 is connected to the rack housing 20 at a position opposite to the intersection with the pinion housing 10. The guide housing 30 includes a holding hole 31 having a circular cross section penetrating the shaft center portion, and the support yoke 3 is fitted and held in the holding hole 31 so as to be slidable in the axial length direction.

  The base end of the support yoke 3 is screwed into the outer opening of the holding hole 31 and faces a support cap 32 that is positioned and fixed by a lock nut 33. A push spring 34 interposed between the support cap 32 and the support yoke 3 is provided. Is urged inward, that is, toward the rack shaft 2. The front end of the support yoke 3 facing the inside of the rack housing 20 is pressed against the peripheral surface of the rack shaft 2 via a rack receiving sheet 4 described later by the spring force of the pressing spring 34.

  With the above configuration, when the steering wheel 14 is operated for steering, the pinion shaft 1 connected to the steering wheel 14 rotates, and this rotation is caused by the rack shaft 2 by the pinion 11 and the rack teeth 21. This movement is converted into movement in the axial length direction, and this movement is transmitted to the left and right wheels for steering.

  At this time, the support yoke 3 presses the rack shaft 2 toward the pinion shaft 1 and applies a preload to the meshing portion between the rack teeth 21 formed on the rack shaft 2 and the pinion 11 provided on the pinion shaft 1. It works to mesh both without backlash. The strength of the preload is appropriately adjusted by increasing or decreasing the screwing amount of the support cap 32. The rack receiving sheet 4 interposed between the support yoke 3 and the rack shaft 2 is in sliding contact with the peripheral surface of the rack shaft 2 moving in the axial length direction, and performs a guiding action for smoothly performing this movement.

  FIG. 2 is an enlarged cross-sectional view of the vicinity of the meshing portion between the rack shaft 2 and the pinion shaft 1, and FIG. 3 is an external perspective view of the support yoke 3 and the rack receiving sheet 4. The support yoke 3 has a cylindrical shape corresponding to the cross section of the holding hole 31 provided in the guide housing 30. A support surface 35 formed in an arch shape corresponding to the outer shape of the rack shaft 2 is provided at the front end of the support yoke 3 (upper end in FIG. 3). An engagement hole 36 is formed.

  The rack receiving sheet 4 is excellent in wear resistance, such as a metal plate material in which a coating film made of PTFE (polyethylene terephthalate) is formed on the surface of an aluminum alloy thin plate, a plate material made of carbon fiber reinforced polyacetanol (POM), etc. The plate material having a low coefficient of friction and having a high strength is curved and formed into an arch shape corresponding to the support surface 35 of the support yoke 3, and at the approximate center of the convex surface of the rack receiving sheet 4, Engagement protrusions 40 having a circular cross section corresponding to the engagement holes 36 are integrally projected.

  The rack receiving sheet 4 configured as described above has an engagement projection 40 fitted into the engagement hole 36 of the support yoke 3 as indicated by an arrow in FIG. 3, and as shown in FIG. It is attached along the surface 35, and a concave surface (receiving surface 41) that faces outward is pressed against the peripheral surface of the rack shaft 2.

  As shown in FIG. 3, a plurality of (four in the figure) concave grooves 42, 42... Are formed on the receiving surface 41 of the rack receiving sheet 4 pressed against the rack shaft 2 in this way. These concave grooves 42, 42... Act as introduction grooves for lubricant supplied as described later, and each of the two concave grooves 42, 42 from both side edges in the axial direction of the rack shaft 2. Is extended toward the inside of the rack shaft 2 in the axial direction.

  Further, the circumferential positions of the two concave grooves 42, 42 on both side edges of the rack receiving sheet 4 are equally distributed to both sides of the central portion in the circumferential direction of the receiving surface 41, and the rack shaft with which the receiving surface 41 is slidably contacted. The inner end portions of the two concave grooves 42 and 42 extending from both side edges are stopped at positions facing each other with an appropriate interval. Further, as shown in FIG. 3, the depth of the concave grooves 42, 42... Is deepest at the positions on both side edges of the rack receiving sheet 4, and is gradually shallowed inward. The width of... Is widest at positions on both side edges of the rack receiving sheet 4 and is gradually narrowed inward.

  In the metal rack receiving sheet 4 described above, such concave grooves 42, 42... Can be formed by pressing a pressing die against one surface before forming the coating film, and are made of a high strength resin. The rack receiving sheet 4 can be formed simultaneously in its own molding process. The cross-sectional shape of the concave grooves 42, 42... Is not limited to the triangular cross section shown in FIG.

  In the support yoke 3 having the rack receiving sheet 4 as described above, grease as a lubricant is applied to the receiving surface 41 in which the concave grooves 42, 42... Are formed, and as shown in FIGS. It is mounted in the formed holding hole 31 as described above, and is used with the receiving surface 41 in sliding contact with the outer periphery of the rack shaft 2. The receiving surface 41 of the rack receiving device 4 has a curved shape that matches the outer shape of the rack shaft 2, and the rack receiving sheet 4 is in sliding contact with the rack shaft 2 over substantially the entire receiving surface 41.

  When the steering operation described above is performed in this state, the rack shaft 2 that moves in the axial length direction is guided by the rack receiving sheet 4 that is in sliding contact with the grease, but the grease previously applied to the rack receiving sheet 4 is used. Is attached to the peripheral surface of the rack shaft 2 and gradually taken out to both sides of the sliding contact portion between the rack shaft 2 and the rack receiving sheet 4. The concave grooves 42, 42... Formed in the rack receiving sheet 4 as described above are provided to re-introduce the grease thus taken out into the sliding contact portion between the rack shaft 2 and the rack receiving sheet 4.

  4 is an explanatory view of the operation of the concave grooves 42, 42... Provided in the rack receiving sheet 3, and shows the sliding contact state of the rack receiving sheet 4 at the site where the concave grooves 42, 42. A cross section taken along line -IV is shown.

  The grease supplied between the rack receiving sheet 4 and the rack shaft 2 adheres to a region indicated by hatching in the drawing on the outer surface of the rack shaft 2 moving in both directions. It is taken out on both sides of the sliding contact portion of the sheet 4. Here, the rack receiving sheet 4 according to the present invention has the concave grooves 42 and 42 formed as described above, and these concave grooves 42 and 42 are in sliding contact with the rack shaft 2 and the rack receiving sheet 4. In the section, as shown in the drawing, a wedge-shaped gap is formed at both side edges in the axial length direction of the rack shaft 2 to reduce the height inward. Accordingly, when the rack shaft 2 moves in the axial direction in the direction indicated by the white arrow in the figure, a part of the grease adhering to the upstream region in the moving direction is a concave having an opening in the same direction. It is received in the groove 42 as indicated by an arrow in the figure and is guided to the inner back side by the wedge effect and returned to the sliding contact surface between the rack shaft 2 and the rack receiving sheet 4.

  The concave grooves 42, 42... Have a shape in which the width is reduced from both side edges of the rack receiving sheet 4 toward the inner back side, so that a wedge effect in the width direction also occurs, and the above-described grease is introduced more reliably. The When the rack shaft 2 moves in the opposite direction, the concave groove 42 having an opening on the other side performs the same introducing action, and the grease is returned to the sliding contact surface between the rack shaft 2 and the rack receiving sheet 4.

  In this way, the concave grooves 42, 42... Provided in the rack receiving sheet 4 receive the grease taken out by adhering to the peripheral surface of the rack shaft 2 and slide the contact portion between the rack shaft 2 and the rack receiving sheet 4. Therefore, the rack shaft 2 is smoothly guided to move over a long period of time by the rack receiving sheet 4 that is in sliding contact with the lubricating grease.

  Therefore, when applied to the rack and pinion type steering apparatus shown in the embodiment, a good steering feeling can be continuously obtained over a long period of time. The rack receiving sheet 4 according to the present invention and the support yoke 3 provided with the rack receiving sheet 4 can be applied to uses other than the rack and pinion type steering device. The rack shaft meshing with the pinion can be smoothly moved and guided over a long period of time.

  In the above-described embodiment, the configuration in which the two concave grooves 42 and 42 that are continuous with the both side edges of the rack receiving sheet 4 are formed at positions that are aligned in the circumferential direction has been described. 42, 42... Can be formed in an appropriate manner including the number, position and shape.

  FIG. 5 is a plan view of the rack receiving sheet 4 showing another embodiment of the concave grooves 42, 42... In this embodiment, two concave grooves 42, 42 extending from both side edges of the rack receiving sheet 4 are formed with different circumferential positions, and these concave grooves 42, 42,. Is extended to the vicinity of the other side edge with respect to the side edge side on which is formed, and is overlapped by a suitable length inside the rack receiving sheet 4.

  In this configuration, when the rack shaft 2 moves in both directions, the rack shaft 2 and the rack receiving sheet 4 are acted upon by the action of the concave grooves 42, 42... Where grease adhering to the peripheral surface of the rack shaft 2 opens at different positions. The grease adhering to a wide area can be reused, and the grease introduced to the extended ends of the concave grooves 42, 42. And good lubricity can be ensured.

  In the above embodiment, the concave grooves 42, 42... As the lubricant introduction grooves are formed from the respective side edges of the rack receiving sheet 4. However, these concave grooves 42, 42 are described. ... should just be formed toward the inner side of the rack receiving sheet 4 from at least one of both side edges. By forming the concave grooves 42, 42... From at least one side edge, the lubricant adhering to the peripheral surface of the rack shaft 2 can be returned to the sliding contact portion between the rack shaft 2 and the rack receiving sheet 4. it can.

  Further, in the above embodiment, the configuration in which the concave grooves 42, 42... As the lubricant introduction grooves are formed so as to extend along the axial direction of the rack shaft 2 has been described. 42... Can be formed obliquely with an appropriate inclination with respect to the axial direction of the rack shaft 2. Also in this case, if the concave grooves 42, 42... Are formed inward from the end in the axial length direction of the rack receiving sheet 4, the lubricant adhering to the peripheral surface of the rack shaft 2 is removed from the rack shaft. 2 and the rack contact sheet 4 can be returned to the sliding contact portion.

It is a longitudinal cross-sectional view which shows the structure of the principal part of the rack and pinion type steering device as an application example of the rack receiving sheet according to the present invention. It is an expanded sectional view near the meshing part of a rack shaft and a pinion shaft. It is an external appearance perspective view of a support yoke and a rack receiving sheet. It is operation | movement explanatory drawing of the ditch | groove provided in the rack receiving sheet. It is a top view of the rack receiving sheet which shows the other formation aspect of a ditch | groove.

Explanation of symbols

1 pinion shaft, 2 rack shaft, 3 support yoke, 4 rack receiving sheet,
11 pinion, 21 rack teeth, 42 concave groove (lubricant introduction groove)

Claims (9)

The rack shaft in which rack teeth meshing with the pinion are arranged in parallel in the axial length direction is pressed from the opposite side of the meshing portion with the pinion, and the rack shaft is moved and guided in the axial length direction while preloading the meshing portion. In the rack receiving sheet that is attached to the support yoke and is in sliding contact with the peripheral surface of the rack shaft via a lubricant,
A rack receiving sheet, comprising: a groove for introducing the lubricant extending from at least one of both side edges in the axial direction of the rack shaft toward the inside in the axial direction.   The rack receiving sheet according to claim 1, wherein the introduction groove is extended from each of the side edges toward the inside in the axial length direction.   The rack receiving sheet according to claim 1 or 2, wherein the introduction groove is formed by reducing the depth from the outside toward the inside in the axial length direction.   The rack receiving sheet according to any one of claims 1 to 3, wherein the introduction groove is formed by reducing a width from the outside toward the inside in the axial length direction.   The rack receiving sheet according to any one of claims 1 to 4, wherein a plurality of the introduction grooves are arranged side by side in the circumferential direction of the rack shaft.   The rack receiving sheet according to any one of claims 2 to 5, wherein the introduction groove is formed by varying a circumferential position on each of both side edges.   The rack receiving sheet according to any one of claims 2 to 5, wherein the introduction groove is formed by aligning positions in a circumferential direction on both side edges. The rack shaft in which rack teeth meshing with the pinion are arranged in parallel in the axial length direction is pressed from the opposite side of the meshing portion with the pinion, and the rack shaft is moved and guided in the axial length direction while preloading the meshing portion. In support yoke,
A support yoke, wherein the rack receiving sheet according to any one of claims 1 to 7 is mounted on a pressing surface to the rack shaft. In the rack and pinion type steering device that converts the rotation of the pinion shaft according to the operation of the steering wheel into the movement in the axial direction of the rack shaft meshing with the pinion shaft, and performs the steering,
9. A steering apparatus comprising: a support yoke according to claim 8, wherein the rack shaft is pressed from the opposite side of the meshing portion with the pinion shaft, and the rack shaft is moved and guided while applying a preload to the meshing portion. .

Images