Rack guide

Abstract

A rack guide is provided which stably supplies lubricant from the rack rod to a lubricant retaining groove when the rack rod slides relative to the rack guide. A lubricant retaining groove (122) extending along the short side direction of the rack guide orthogonal to the length direction of the rack guide and retaining the lubricant (G) between the rack rod (SD3) and the support surface (120A) is arranged on the support surface (120A), and the lubricant retaining groove (122) has a bow-shaped lubricant introduction area (122a) for introducing the lubricant (G) and a lubricant introduction area (122a) connected to the lubricant introduction area (122a) for receiving the lubricant introduced from the lubricant introduction area (122a). A lubricant retaining area (122b) is provided for retaining the lubricant (G), the lubricant retaining area (122b) of the lubricant retaining groove (122) is arranged in a contact area (120A1) of the supporting surface (120A), and the lubricant introduction area (122a) of the lubricant retaining groove (122) is arranged in an interval opposing area (120A2o) outside the supporting surface (120A) and is formed to be symmetrical with respect to a central axis (A) in a groove length direction parallel to a short side direction of the base.

Description

Technical Field

[0001] The present invention relates to a rack guide for a steering device for changing a steering angle of a tire, and more particularly to a rack guide for guiding a rack bar along a length direction of the bar. Background Art

[0002] A rack guide having a multi-layer sliding sheet for supporting the rack rod has been known as a rack guide for guiding the rack rod in the length direction (for example, refer to Patent Document 1), wherein the multi-layer sliding sheet has: a pair of inclined surface portions facing each other, a pair of flat surface portions respectively connected to the inclined surface portions, a bottom surface portion respectively connected to the flat surface portions, and a hollow protrusion extending toward the back metal side at the center of the bottom surface portion.

[0003] (Prior art literature)

[0004] (Patent Document)

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-116994 (see in particular Figure 2 ) Summary of the invention

[0006] (Problems to be solved by the invention)

[0007] The recessed portion of the inclined surface of the multi-layer sliding sheet of the rack guide is filled with lubricating oil. When the rack bar moves along the length direction of the rack bar, the lubricating oil filled in the recessed portion is supplied to the rack bar. However, since the lubricating oil in the recessed portion is not replenished sufficiently, there is a risk that the lubricating oil in the recessed portion will be exhausted.

[0008] Therefore, the present invention is an invention for solving the above-mentioned problems of the prior art. That is, an object of the present invention is to provide a rack guide that stably supplies lubricant from the rack bar to the lubricant retaining groove when the rack bar slides relative to the rack guide.

[0009] (Measures taken to solve the problem)

[0010] The invention according to claim 1 is a rack guide having a supporting surface for a steering device, wherein the rack guide supports a sliding surface provided behind a meshing surface of a rack bar having a D-shaped cross section and guides the rack bar along the rod length direction of the rack bar to change the steering angle of the tire, the rack bar meshes with a pinion formed on a steering shaft to convert the rotational motion of the steering shaft into a linear motion, the sliding surface of the rack bar is a curved surface formed with a single radius of curvature, the supporting surface is a curved surface having a contact area slidably contacting the rack bar and an interval-opposing area spaced apart from the rack bar, the contact area being sandwiched between the inner interval-opposing area and the outer interval-opposing area, the inner interval-opposing area being close to the rack guide length direction extending in the rack guide length direction parallel to the sliding direction of the rack bar. The lubricant retaining groove is provided on the supporting surface, and the lubricant retaining groove has a bow-shaped lubricant introduction area for introducing the lubricant and a lubricant retaining area connected to the lubricant introduction area to retain the lubricant introduced from the lubricant introduction area. The lubricant retaining area of ​​the lubricant retaining groove is provided in the contact area of ​​the supporting surface. The lubricant introduction area of ​​the lubricant retaining groove is provided in the outer spaced opposing areas of the supporting surface and is formed symmetrically with respect to the center axis of the groove length direction parallel to the short side direction of the rack guide, thereby solving the above-mentioned problem.

[0011] In the invention according to claim 2 , based on the structure of the rack guide described in claim 1 , the lubricant retaining area is orthogonal to the contact area of ​​the support surface extending along the length direction of the rack guide, thereby further solving the above-mentioned problem.

[0012] In the invention according to claim 3 , based on the structure of the rack guide according to claim 1 or claim 2 , the lubricant retaining region extends to the spaced-apart region on the inner side of the support surface, thereby further solving the above-mentioned problem.

[0013] Based on the structure of the rack guide described in claim 1 or claim 2, in the invention involved in claim 4, the opposing surface opposite to the sliding surface of the rack rod is arranged on the outside of the supporting surface and is farther away from the rack rod than the supporting surface, thereby further solving the above-mentioned problem.

[0014] (Effects of the Invention)

[0015] According to the rack guide of the invention involved in claim 1, a lubricant retaining groove extending in the short side direction of the rack guide orthogonal to the longitudinal direction of the rack guide and retaining the lubricant existing between the rack bar and the supporting surface is arranged on the supporting surface, the lubricant retaining groove has a bow-shaped lubricant introduction area for introducing lubricant and a lubricant retaining area connected to the lubricant introduction area and retaining the lubricant introduced from the lubricant introduction area, the lubricant retaining area of ​​the lubricant retaining groove is arranged in the contact area of ​​the supporting surface, and the lubricant introduction area of ​​the lubricant retaining groove is arranged on the outer side of the supporting surface. The lubricant retaining area of ​​the lubricant retaining groove is provided in the lubricant inlet area, and the lubricant retaining area is provided in the lubricant inlet area. As a result, the lubricant flows into the lubricant inlet area where the lubricant becomes less along with the flow of the rack bar. Therefore, the lubricant can be stably supplied to the lubricant retaining groove through the rack bar.

[0016] In addition, the lubricant inlet area of ​​the lubricant retaining groove is formed to be symmetrical with respect to the central axis in the groove length direction parallel to the short side direction of the rack guide. Therefore, the amount of lubricant flowing into the lubricant inlet area does not depend on the sliding direction of the rack rod orthogonal to the short side direction of the rack guide. Therefore, the total amount of lubricant in the supporting surface does not depend on the number and position of the lubricant retaining grooves, thereby improving the configuration freedom of the lubricant retaining grooves on the supporting surface.

[0017] According to the rack guide involved in claim 2, on the basis of the effect exerted by the rack guide of the invention involved in claim 1, the lubricant retaining area is orthogonal to the contact area of ​​the supporting surface extending along the length direction of the rack guide, whereby the lubricant retained in the lubricant retaining area is more easily adhered to the rack bar than flowing in the short side direction of the rack guide as the rack bar slides along the length direction. Therefore, when the rack bar slides relative to the rack guide, the lubricant can be stably supplied from the lubricant retaining groove to the rack bar, and stable replenishment of the lubricant from the rack bar to the lubricant retaining groove and stable supply of the lubricant from the lubricant retaining groove to the rack bar can be achieved at the same time.

[0018] According to the rack guide involved in claim 3, on the basis of the effect exerted by the rack guide of the invention involved in claim 1 or claim 2, the lubricant retaining area extends to the spaced opposing area on the inner side of the supporting surface, whereby the lubricant introduced from the lubricant introduction area to the lubricant retaining groove spreads to the spaced opposing area on the inner side of the supporting surface, and the lubricant spread to the spaced opposing area on the inner side of the supporting surface circulates to the spaced opposing area on the outer side of the supporting surface under the action of the sliding of the rack bar. Therefore, compared with the case where the lubricant retaining area does not extend to the spaced opposing area on the inner side of the supporting surface, more lubricant that contributes to the sliding of the rack bar can be retained to extend the life of the rack bar.

[0019] According to the rack guide involved in claim 4, on the basis of the effect exerted by the rack guide of the invention involved in claim 1 or claim 2, the opposing surface opposite to the sliding surface of the rack bar is arranged on the outside of the supporting surface and at a position farther away from the rack bar than the supporting surface. Therefore, even if the rack bar slides relative to the rack guide and the lubricant between the rack bar and the supporting surface overflows from between the rack bar and the supporting surface, since the lubricant accumulates between the sliding surface and the opposing surface of the rack bar, not only can the lubricant be easily stored in the rack guide, but the lubricant accumulated between the sliding surface and the opposing surface of the rack bar can also adhere to the rack bar and be supplied to the lubricant retaining groove. Therefore, the lubricant can circulate between the entire supporting surface of the rack guide and the rack bar. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional view of a rack and pinion steering device incorporating a rack guide as one embodiment of the present invention.

[0021] Figure 2 for Figure 1 A perspective view of a rack guide is shown.

[0022] Figure 3 To show Figure 1 A side view showing the arrangement relationship between the rack guide and the rack rod.

[0023] Figure 4 For Figure 3 A top view of the rack guide when viewed from the IV direction.

[0024] Figure 5A It is a top view for explaining the flow of the lubricant when the rack bar is moved to the right on the paper.

[0025] Figure 5B It is a top view for explaining the flow of the lubricant when the rack bar is moved to the left in the paper.

[0026] Figure 6 For observation from IV direction Figure 5Aand Figure 5B Side view of the rack guide.

[0027] Fig. 7A It is a top view of a rack guide which is a first modified example of the present invention.

[0028] Figure 7B It is a top view of a rack guide which is a second modified example of the present invention.

[0029] Figure 7C It is a top view of a rack guide which is a third modified example of the present invention. DETAILED DESCRIPTION

[0030] The rack guide for a steering device of the present invention comprises a supporting surface, wherein the supporting surface supports a sliding surface formed behind the meshing surface of a rack bar having a D-shaped cross section and guides the rack bar along the rod length direction of the rack bar to change the steering angle of the tire, wherein the rack bar meshes with a pinion formed on the steering shaft to convert the rotational motion of the steering shaft into a linear motion, wherein the sliding surface of the rack bar is a curved surface formed with a single curvature radius, and the supporting surface is a curved surface having a contact area that is in free sliding contact with the rack bar and an interval-opposing area that is spaced apart from the rack bar, wherein the contact area is sandwiched between the inner interval-opposing area and the outer interval-opposing area, wherein the inner interval-opposing area is close to the center axis of the rack guide in the length direction extending in the rack guide length direction parallel to the sliding direction of the rack bar, and the outer interval-opposing area is away from the rack guide. The lubricant retaining groove is provided on the supporting surface and extends along the short side direction of the rack guide orthogonal to the long side direction of the rack guide and retains the lubricant existing between the rack rod and the supporting surface. The lubricant retaining groove has a bow-shaped lubricant introduction area for introducing lubricant and a lubricant retaining area connected to the lubricant introduction area and retaining the lubricant introduced from the lubricant introduction area. The lubricant retaining area of ​​the lubricant retaining groove is arranged in the contact area of ​​the supporting surface. The lubricant introduction area of ​​the lubricant retaining groove is arranged in the spaced opposing areas outside the supporting surface and is formed to be symmetrical with respect to the central axis of the groove length direction parallel to the short side direction of the rack guide. As long as the lubricant is stably supplied from the rack rod to the lubricant retaining groove when the rack rod slides relative to the rack guide, the specific implementation of the present invention can be in any form.

[0031] For example, the rack guide of the present invention is a guide for a rack and pinion steering device mounted on a four-wheeled vehicle. The four-wheeled vehicle may be not only a gasoline vehicle or a diesel vehicle but also an electric vehicle or the like.

[0032] Embodiment 1

[0033] The following is based on Figures 1 to 6 , a rack guide 100 as an embodiment of the present invention will be described.

[0034] <1. Installation environment of rack guide>

[0035] First, based on Figure 1 , the environment in which the rack guide 100 is mounted is described. Figure 1 It is a cross-sectional view of a rack and pinion steering device incorporating a rack guide as one embodiment of the present invention.

[0036] like Figure 1 As shown, the rack guide 100 of the present embodiment is mounted on a rack and pinion steering device SD of a four-wheeled vehicle.

[0037] The rack and pinion steering device SD is used to change the steering angle of a tire (not shown), and includes a device housing SD1, a steering shaft SD2 that rotates integrally with a steering wheel, a rack rod SD3 that meshes with the steering shaft SD2 and converts the rotational motion of the steering shaft SD2 into linear motion, a rack guide 100 that guides the rack rod SD3 along the rod length direction of the rack rod SD3, and an energizing spring SD4 that presses the rack guide 100 toward the rack rod SD3.

[0038] A pinion gear SD2 a meshing with the rack bar SD3 is formed at the front end of the steering shaft SD2 , and the pinion gear SD2 a rotates integrally with the steering shaft SD2 .

[0039] like Figure 1 As shown, the rack bar SD3 has a sliding surface SD3a which is a curved surface formed with a single curvature radius Rb and an engaging surface SD3b which is provided behind the sliding surface SD3a and serves as a rack tooth that engages with the steering shaft SD2, and has a D-shaped cross section.

[0040] The energizing spring SD4 is sandwiched between the device housing SD1 and the rack guide 100 .

[0041] <2. Structure of rack guide>

[0042] Next, based on Figures 1 to 4 , the structure of the rack guide 100 is described in detail.

[0043] Figure 2 for Figure 1 A perspective view of the rack guide shown, Figure 3 To show Figure 1 The side view of the configuration relationship between the rack guide and the rack rod shown in FIG. Figure 4 For Figure 3 A top view of the rack guide when viewed from the IV direction.

[0044] like Figure 2 As shown in FIGS. 1 and 10 , the rack guide 100 includes a rack guide body 110 and a base 120 .

[0045] <2.1. Rack guide body>

[0046] like Figure 2 As shown, the rack guide body 110 is a cylindrical metal component.

[0047] In addition, a rack guide body 110 is formed at one end thereof with a central axis (rack guide central axis GA) extending in the direction of the rack guide body 110. Figure 2 The length direction of the base mounting groove ( Figure 2 A base mounting groove 111 extending in the x direction (in the x direction).

[0048] like Figure 1 and Figure 3 As shown, the cross-sectional shape of the base mounting groove 111 is semicircular.

[0049] In addition, if Figure 1 As shown, a base engaging hole 111 a 1 that engages with the convex portion 121 of the base 120 is formed on the facing surface 111 a of the base mounting groove 111 that faces the sliding surface SD3 a of the rack bar SD3 .

[0050] <2.2. Base>

[0051] The base 120 is a member made of a resin having excellent self-lubricating properties (for example, a fluororesin such as PTFE, a nylon resin, or a polyacetal resin such as POM). Figure 3 As shown, the thickness is roughly uniform.

[0052] In addition, if Figure 1 and Figure 4 As shown, in a top view, a protrusion 121 is formed at the center of the base 120 and protrudes toward the rack guide body 110 .

[0053] The convex portion 121 is inserted into and engaged with the base engaging hole 111 a 1 of the rack guide body 110 , so that the base 120 and the rack guide body 110 are integrated.

[0054] Therefore, when the base 120 is assembled to the rack guide body 110, Figure 3 As shown, the facing surface 111a of the rack guide body 110 facing the sliding surface SD3a of the rack bar SD3 is arranged at a position farther from the rack bar SD3 than the supporting surface 120A of the base 120 supporting the sliding surface SD3a of the rack bar SD3.

[0055] In addition, if Figure 2As shown in FIGS. 1 and 2 , the outer shape of the base 120 is smaller than the outer shape of the facing surface 111 a of the rack guide body 110 . Therefore, the facing surface 111 a of the rack guide body 110 is located outside the support surface 120A of the base 120 .

[0056] like Figure 4 As shown, the support surface 120A of the base 120 is relative to the center of the protrusion 121 and along the length direction of the base ( Figure 4 The base is symmetrical with respect to the base longitudinal center axis LA extending in the X direction (in the X direction) and passing through the center of the protrusion 121 and along the base short side direction ( Figure 4 The base is symmetrical with respect to the central axis WA extending in the short side direction of the base (in the Y direction).

[0057] The base longitudinal center axis LA and the base short side center axis WA are orthogonal to the rack guide center axis GA.

[0058] The base length direction of the base 120 is the same as the base mounting groove length direction of the rack guide body 110 and the length direction (sliding direction) of the rack bar SD3, and the base length direction center axis LA is coaxial with the rack guide length direction center axis.

[0059] The base short side direction of the base 120 is orthogonal to the base long side direction of the base 120 , and the base short side direction central axis WA is coaxial with the rack guide short side direction central axis.

[0060] In addition, if Figure 3 As shown, when the base 120 is assembled to the rack guide body 110 , the support surface 120A has two curvature centers Os1 and Os2 .

[0061] like Figure 3 As shown, the centers of curvature Os1 and Os2 are arranged with the rack guide center axis GA interposed therebetween in the Y direction and their arrangement positions in the z direction are substantially equal.

[0062] In addition, the radius of curvature of the center of curvature Os1 and the radius of curvature of the center of curvature Os2 are the same radius of curvature Rs.

[0063] That is, the support surface 120A is formed by combining two curved surfaces, and is not formed by a single curved surface like the sliding surface SD3 a of the rack bar SD3 .

[0064] Furthermore, the curvature center Ob of the rack bar SD3 is located on the rack guide center axis GA.

[0065] As can be seen from the above, when the base 120 is assembled on the rack guide body 110, Figure 3 and Figure 4As shown, the support surface 120A includes a contact region 120A1 slidably in contact with the rack bar SD3 and a spaced-opposing region 120A2 spaced-opposingly opposed to the rack bar SD3 .

[0066] like Figure 3 and Figure 4 As shown, there are two contact areas 120A1 sandwiched between the center axis LA in the length direction of the base, and the two contact areas 120A1 are sandwiched between the inner side (the side close to the center axis LA in the length direction of the base) and the outer side (the side away from the center axis LA in the length direction of the base) of the short side direction (Y direction) of the rack guide. The opposing area 120A2i and the outer side (the side away from the center axis LA in the length direction of the base) are respectively sandwiched.

[0067] <2.2.1. Lubricant Retaining Groove>

[0068] like Figure 2 and Figure 4 As shown in FIG. 1 , the support surface 120A of the base 120 is formed with a plurality of lubricant retaining grooves 122 for retaining lubricant between the sliding surface SD3 a of the rack bar SD3 and the support surface 120A of the base 120 so that the rack bar SD3 slides smoothly relative to the base 120 .

[0069] like Figure 4 As shown in FIG. 1 , the lubricant retaining groove 122 is disposed on the support surface 120A in a symmetrical manner with respect to the base longitudinal direction central axis LA and the base short side direction central axis WA.

[0070] The lubricant retaining groove 122 is a groove with a constant depth and is Figure 4 As shown, it extends along the short side direction of the base (the short side direction of the rack guide).

[0071] In addition, if Figure 4 As shown, the lubricant retaining groove 122 is formed symmetrically with respect to a center axis A in the groove length direction parallel to the short side direction of the rack guide.

[0072] In addition, if Figure 4 As shown, the lubricant retaining groove 122 has a bow-shaped lubricant introduction area 122a for introducing lubricant and a lubricant retaining area 122b connected to the lubricant introduction area 122a and retaining the lubricant introduced from the lubricant introduction area 122a.

[0073] like Figure 4 As shown, the lubricant introduction area 122a is an end portion of the lubricant retaining groove 122 that is away from the center axis LA in the longitudinal direction of the base and has a bow shape.

[0074] Furthermore, the lubricant introduction region 122a is provided in the spacing-opposing region 120A2o outside the support surface 120A.

[0075] like Figure 4 As shown, the lubricant retaining region 122b is orthogonal to the contact region 120A1 of the support surface 120A, and extends to the spacing opposing region 120A2i inside the support surface 120A.

[0076] <3. Flow of Lubricant>

[0077] Next, based on FIG. 5A to FIG. 6 , the flow of the lubricant G between the rack bar SD3 and the rack guide 100 will be described.

[0078] Figure 5A This is a top view for explaining the flow of lubricant when the rack bar is moved to the right on the paper. Figure 5B This is a top view for explaining the flow of lubricant when the rack bar is moved to the left on the paper. Figure 6 For observation from IV direction Figure 5A and Figure 5B Side view of the rack guide.

[0079] In the rack and pinion steering device SD described above, the lubricant G is applied to the rack bar SD3. Therefore, when the rack bar SD3 slides on the rack guide 100, the lubricant G is applied to the rack bar SD3. FIG. 5A to FIG. 6 It is shown as being between the rack bar SD3 and the rack guide 100 .

[0080] <3.1. Flow of lubricant near the lubricant introduction area>

[0081] First, based on Figure 5A and Figure 5B , the flow of the lubricant G in the vicinity of the lubricant introduction region 122 a of the lubricant retaining groove 122 will be described.

[0082] like Figure 5A and Figure 5B As shown by the gray arrow in FIG. 1 , the lubricant G attached to the rack bar SD3 flows on the support surface 120A of the base 120 along the sliding direction of the rack bar SD3 .

[0083] In addition, as shown by the white arrow, the lubricant G attached to the outer spacing opposing area 120A2o on the base 120 side also flows along the length direction of the base along with the movement of the lubricant G on the rack rod SD3 side, and flows into the lubricant retaining groove 122 from the lubricant inlet area 122a of the lubricant retaining groove 122.

[0084] Among them, the lubricant introduction region 122a of the lubricant retaining groove 122 is in the shape of a bow, and therefore the lubricant G flowing into the lubricant retaining groove 122 flows toward the center axis LA in the longitudinal direction of the base.

[0085] <3.2. Flow of Lubricant in Lubricant Retention Area>

[0086] Secondly, based on Figure 5A and Figure 5B , the flow of the lubricant G in the lubricant retaining region 122 b of the lubricant retaining groove 122 will be described.

[0087] Of the lubricant G held in the lubricant holding region 122 b , a portion of the lubricant G located in the contact region 120A1 of the bearing surface 120A adheres to the sliding surface SD3 a of the rack bar SD3 .

[0088] Of the lubricant G retained in the lubricant retaining area 122b, a portion of the lubricant G in the spaced-apart area 120A2i located inside the support surface 120A flows out of the lubricant retaining groove 122 in the sliding direction of the rack bar SD3 and in the direction toward the center axis LA in the longitudinal direction of the base as the rack bar SD3 moves.

[0089] Therefore, in the present embodiment, the lubricant G between the rack bar SD3 and the support surface 120A is gathered toward the base longitudinal direction central axis LA.

[0090] <3.3. Flow of Lubricant in the Vicinity of the End of the Support Surface on the Sliding Direction Side of the Rack Bar>

[0091] Next, based on FIG. 5A to FIG. 6 , the flow of the lubricant G in the vicinity of the end portion of the support surface 120A on the rack bar sliding direction side will be described.

[0092] In the spaced facing region 120A2i inside the support surface 120A, as described above, the lubricant G is sufficient, and therefore the lubricant G flows into the facing surface 111a as the rack bar SD3 slides.

[0093] In addition, if Figure 6 As shown, the lubricant G is filled between the rack bar SD3 and the facing surface 111 a , and the lubricant G flows toward the spacing facing region 120A2 o outside the support surface 120A as indicated by the black arrow.

[0094] When the lubricant G flows between the rack bar SD3 and the facing surface 111 a to the outer spaced facing region 120A2 o of the support surface 120A, it adheres to the rack bar SD3 in the outer spaced facing region 120A2 o.

[0095] Then, as described in <3.1> above, the lubricant adhering to the rack bar SD3 flows into the support surface 120A again and is introduced into the lubricant introduction region 122 a of the lubricant retaining groove 122 .

[0096] <3.4. Flow of Lubricant Near the End of the Support Surface on the Side Opposite to the Sliding Direction of the Rack Bar>

[0097] Next, based on Figure 5A and Figure 5B , the flow of the lubricant G in the vicinity of the end portion of the support surface 120A on the side opposite to the rack bar sliding direction side will be described.

[0098] When the lubricant G attached to the rack bar SD3 reaches the upper portion of the support surface 120A, the lubricant G located in the contact area 120A1 of the support surface 120A is difficult to flow into between the rack bar SD3 and the support surface 120A. Figure 5A and Figure 5B As shown, most of the liquid flows toward the outer spaced-opposing region 120A2o or the inner spaced-opposing region 120A2i, and flows from the outer spaced-opposing region 120A2o or the inner spaced-opposing region 120A2i into between the rack bar SD3 and the support surface 120A.

[0099] <4. Effect>

[0100] According to the rack guide 100 of the present embodiment described above, a lubricant retaining groove 122 is provided on the support surface 120A, extending along the base short side direction (rack guide short side direction) perpendicular to the base length direction (rack guide length direction) and retaining the lubricant G between the rack bar SD3 and the support surface 120A. The lubricant retaining groove 122 has a bow-shaped lubricant introduction area 122a for introducing the lubricant G and a lubricant retaining area 122b connected to the lubricant introduction area 122 and retaining the lubricant G introduced from the lubricant introduction area 122a. The lubricant retaining area 122b of the lubricant retaining groove 122 is provided in the contact area 120A1 of the support surface 120A, and the lubricant introduction area 122a of the lubricant retaining groove 122 is provided in the support surface 120A. The spaced opposing area 120A2o is provided on the outer side of the bearing surface 120A. As a result, when the rack rod SD3 slides along the length direction of the rod, even if the lubricant G retained in the lubricant retaining area 122b of the lubricant retaining groove 122 flows out from the lubricant retaining groove 122 to the outside of the lubricant retaining groove 122 under the drag of the lubricant G attached to the rack rod SD3, the lubricant G existing in the lubricant introduction area 122a is replenished to the lubricant retaining area 122b along with the outflow of the lubricant G in the lubricant retaining area 122b of the lubricant retaining groove 122. As a result, the lubricant G flows into the lubricant introduction area 122a where the lubricant G becomes less along with the flow of the rack rod SD3. Therefore, the lubricant G can be stably replenished to the lubricant retaining groove 122 through the rack rod SD3.

[0101] Therefore, the lubricant G adhering to the sliding surface SD3a of the rack bar SD3 can be used evenly, and the replacement time of the lubricant G can be extended.

[0102] In addition, the lubricant introduction area 122a of the lubricant retaining groove 122 is formed to be symmetrical with respect to the central axis A in the groove length direction parallel to the short side direction of the base. Therefore, the amount of lubricant G flowing into the lubricant introduction area 122a does not depend on the sliding direction of the rack rod orthogonal to the short side direction of the base. Therefore, the total amount of lubricant G in the supporting surface 120A does not depend on the number and position of the lubricant retaining grooves 122, thereby improving the configuration freedom of the lubricant retaining grooves 122 on the supporting surface 120A.

[0103] Furthermore, the lubricant retaining area 122b is orthogonal to the contact area 120A1 of the supporting surface 120A extending along the length direction of the base, whereby the lubricant G retained in the lubricant retaining area 122b is more easily adhered to the rack bar SD3 than flowing in the short side direction of the base as the rack bar SD3 slides along the length direction. Therefore, when the rack bar SD3 slides relative to the rack guide 100, the lubricant G can be stably supplied from the lubricant retaining groove 122 to the rack bar SD3. As a result, when the rack bar SD3 slides relative to the rack guide 100, stable replenishment of the lubricant G from the rack bar SD3 to the lubricant retaining groove 122 and stable supply of the lubricant G from the lubricant retaining groove 122 to the rack bar SD3 can be achieved simultaneously.

[0104] In addition, the lubricant retaining area 122b extends to the interval opposing area 120A2i on the inner side of the support surface 120A, whereby the lubricant G introduced from the lubricant introduction area 122a into the lubricant retaining groove 122 spreads to the interval opposing area 120A2i on the inner side of the support surface 120A. The lubricant G that spreads to the interval opposing area 120A2i on the inner side of the support surface 120A circulates to the interval opposing area 120A2o on the outer side of the support surface 120A under the action of the sliding of the rack bar SD3. Therefore, compared with the case where the lubricant retaining area does not extend to the interval opposing area on the inner side of the support surface, more lubricant G that contributes to the sliding of the rack bar SD3 can be retained, thereby extending the life of the rack bar 100.

[0105] Furthermore, the opposing surface 111a opposite to the sliding surface SD3a of the rack bar SD3 is arranged on the outside of the support surface 120A and is farther away from the rack bar SD3 than the support surface 120A. Therefore, even if the rack bar SD3 slides relative to the rack guide 100 and the lubricant G between the rack bar SD3 and the support surface 120A overflows from between the rack bar SD3 and the support surface 120A, since the lubricant G accumulates between the sliding surface SD3a and the opposing surface 111a of the rack bar SD3, not only can the lubricant G be easily stored on the rack guide 100, but the lubricant G accumulated between the sliding surface SD3a and the opposing surface 111a of the rack bar SD3 can also adhere to the rack bar SD3 and be supplied to the lubricant retaining groove 122. Therefore, the lubricant G can circulate between the entire support surface 120A of the rack guide 100 and the rack bar SD3.

[0106] <Modification>

[0107] As mentioned above, although the rack guide which is an embodiment of the present invention is demonstrated respectively, the rack guide of the present invention is not limited to the rack guide of the above-mentioned embodiment.

[0108] For example, in the above embodiment, the rack guide body 110 is made of metal, but the material of the rack guide body is not limited to metal, and may be resin, for example.

[0109] For example, in the above embodiment, the thickness of the base 120 is uniform, but the thickness of the base may also be non-uniform.

[0110] For example, in the above-described embodiment, the number of the lubricant retaining grooves 122 in the base 120 is 14, but the number is not limited to 14.

[0111] For example, in the above embodiment, the rack guide 100 is composed of two components, namely, the rack guide body 110 and the base 120 , but the rack guide body and the base may be formed as one body.

[0112] For example, in the above-mentioned embodiment, the lubricant retaining groove 122 formed in the base 120 is as follows: Figure 4 As shown in the figure, it is generally formed by a bow-shaped lubricant introduction area 122a and a lubricant retaining area 122b connected to the lubricant introduction area 122a, but the shape of the lubricant introduction area of ​​the lubricant retaining groove is not limited to the above embodiment, as long as it is formed symmetrically with respect to the central axis of the groove length direction and inclined with respect to the central axis of the groove length direction. For example, it can also be 7A to 7C Shape shown.

[0113] That is, it is possible to use a rack guide as shown in the top view of the first modified example of the present invention. Fig. 7AAs in the rack guide 200 shown in the figure, the lubricant introduction area 222a is formed in a trapezoidal shape, and may be formed in a top view of a rack guide as a second modified example of the present invention. Figure 7B As in the rack guide 300 shown in the figure, the lubricant introduction area 322a is formed in a semicircular shape, and it can also be formed as shown in the top view of the rack guide of the third modified example of the present invention. Figure 7C Like the rack guide 400 shown in the figure, the lubricant introduction area 422a is formed by combining two arcs.

[0114] That is, the "bow shape" includes a trapezoidal shape ( Fig. 7A ), semicircular( Figure 7B ), the shape formed by two arcs ( Figure 7C ) shape, "bow shape" is not limited to the above embodiments (for example, Figure 4 ) shape.

[0115] In addition, in the above-mentioned embodiment, the edge on one side of the central axis of the base length direction of the lubricant retaining area close to the lubricant retaining groove is a straight line roughly parallel to the length direction of the rack guide, but the edge on one side of the central axis of the base length direction of the lubricant retaining area close to the lubricant retaining groove may not be roughly parallel to the length direction of the rack guide, and may not be a straight line.

[0116] For example, in the above embodiment, the lubricant retaining groove 122 is formed to be symmetrical with respect to the central axis in the length direction of the groove, but the lubricant retaining area may not be formed to be symmetrical with respect to the central axis in the length direction of the groove, as long as the lubricant introduction area of ​​the lubricant retaining groove is formed to be symmetrical with respect to the central axis in the length direction of the groove.

[0117] (Explanation of Reference Numerals)

[0118] 100, 200, 300, 400: rack guide; 110: rack guide body;

[0119] 111: base mounting groove; 111a: opposing surface; 111a1: base engaging hole; 120: base;

[0120] 120A: supporting surface; 120A1: contact area; 120A2: interval opposing area;

[0121] 120A2i: inner spaced opposing region; 120A2o: outer spaced opposing region;

[0122] 121: convex portion; 122, 222, 322, 422: lubricant retaining groove;

[0123] 122a: lubricant introduction area; 122b: lubricant holding area;

[0124] SD: rack and pinion steering device; SD1: device housing; SD2: steering shaft;

[0125] SD2a: pinion; SD3: rack rod; SD3a: sliding surface;

[0126] SD3b: meshing surface (rack teeth); SD4: energizing spring; GA: rack guide center axis;

[0127] LA: Center axis of the base length direction (center axis of the rack guide length direction);

[0128] WA: Center axis of the short side of the base (center axis of the short side of the rack guide);

[0129] A: symmetry axis in the length direction of the slot; Rb: curvature radius of the rack rod; Rs: curvature radius of the base;

[0130] Os1: center of curvature of the base; Os2: center of curvature of the base; Ob: center of curvature of the rack rod;

[0131] G: Lubricant.

Claims

1. A rack guide having a support surface for a steering device, wherein the support surface supports a sliding surface provided behind a meshing surface of a rack bar having a D-shaped cross section and guides the rack bar along the rod length direction of the rack bar to change the steering angle of the tire, wherein the rack bar meshes with a pinion formed on a steering shaft to convert the rotational motion of the steering shaft into a linear motion, wherein: The sliding surface of the rack bar is a curved surface formed with a single curvature radius. The support surface is a curved surface having a contact area that is in slidable contact with the rack bar and a spaced-opposing area that is spaced-opposing with the rack bar. The contact area is sandwiched between an inner spaced-opposing area and an outer spaced-opposing area, the inner spaced-opposing area is close to a central axis of the rack guide in a length direction extending along a rack guide length direction parallel to a sliding direction of the rack bar, and the outer spaced-opposing area is away from the central axis of the rack guide in a length direction. A lubricant retaining groove extending along the short side direction of the rack guide orthogonal to the longitudinal direction of the rack guide and retaining the lubricant existing between the rack bar and the support surface is arranged on the support surface, The lubricant retaining groove includes a bow-shaped lubricant introduction area for introducing the lubricant and a lubricant retaining area connected to the lubricant introduction area to retain the lubricant introduced from the lubricant introduction area. The lubricant retaining area of ​​the lubricant retaining groove is arranged in the contact area of ​​the bearing surface. The lubricant introduction region of the lubricant retaining groove is provided in the spaced-apart region on the outer side of the support surface and is formed symmetrically with respect to a center axis in a groove length direction parallel to a short side direction of the rack guide.

2. The rack guide according to claim 1, wherein: The lubricant retaining region is orthogonal to a contact region of the support surface extending along the length direction of the rack guide.

3. The rack guide according to claim 1 or claim 2, wherein: The lubricant retaining region extends to a spaced-apart region on the inner side of the support surface.

4. The rack guide according to claim 1 or claim 2, wherein: The facing surface facing the sliding surface of the rack bar is arranged outside the support surface and at a position farther from the rack bar than the support surface.

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