Rack guide and gear mechanism

Abstract

To provide: a rack guide that can stably support a rack bar while preventing knock sounds from occurring; and a gear mechanism using the rack guide.SOLUTION: A rack guide 30 comprises: a columnar rack guide main body 31 made of a synthetic resin, with a distal surface formed with a guide surface 310 being in sliding contact with a back surface of a rack bar; support parts 32a, 32b made of a synthetic resin, projecting from an outer circumferential surface 311 of the rack guide main body 31, and movable in a radial direction of the rack guide main body 31; and biasing parts 33a, 33b made of a synthetic resin, provided on the respective support parts 32a, 32b, and extending in a circumferential direction of the rack guide main body 31, from both sides of the support parts 32a, 32b in the circumferential direction and connected to the rack guide main body 31 so as to bias the support parts 32a, 32b in the radially outer direction of the rack guide main body 31.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a rack guide (support yoke) that supports a rack bar by pressing it against a pinion while guiding the rack bar in the axial direction in a rack and pinion used in an automobile steering device or the like, and to a gear mechanism using the same. [Background technology]

[0002] In rack and pinion gears used in automotive steering devices, for example, a rack guide is known, such as that described in Patent Document 1, which is disposed on the rear side (the side opposite the rack gear) of a rack bar housed in a housing and supports the rack bar by pressing it against the pinion while guiding the rack bar in the axial direction. This rack guide is movably housed in the housing and is biased in the axial direction by a spring, thereby sliding against the rear side of the rack bar and supporting the rack bar. The outer peripheral surface of the rack guide is provided with a plurality of narrow slits extending in the axial direction at equal intervals, and each slit is embedded with a rod-shaped solid lubricant that is exposed from the outer peripheral surface of the rack guide and slides against the inner peripheral surface of the housing. This solid lubricant allows the rack guide to be housed in the housing without any play, preventing the generation of hammering noise caused by the rack guide rattling inside the housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-178935 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the rack guide described in Patent Document 1 has a structure in which rod-shaped solid lubricants are embedded in each of a plurality of slits provided on the outer circumferential surface of the rack guide, which increases the number of parts and the number of steps, thereby increasing costs.

[0005] The present invention has been made in consideration of the above circumstances, and its object is to provide a rack guide that can be manufactured inexpensively and can stably support a rack bar while preventing the generation of striking noise, and a gear mechanism using the same. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a rack guide made of synthetic resin, including: a cylindrical rack guide main body having a guide surface formed on its tip surface that slides against the back surface of a rack bar; a plurality of support parts that protrude from the outer peripheral surface of the rack guide main body and are movable in the radial direction of the rack guide main body; and synthetic resin biasing parts that are provided for each support part, extend circumferentially from both sides of the support parts in the circumferential direction of the rack guide main body, connect to the rack guide main body, and bias the support parts radially outward of the rack guide main body. Here, the outer peripheral surface of the rack guide main body may be provided with a housing part that houses the support parts together with the biasing parts.

[0007] For example, the rack guide of the present invention is A rack guide slidably supports a rack bar, on which a rack gear that meshes with a pinion gear is formed, from an opposite side of the rack gear, and guides the rack bar, which moves in accordance with rotation of the pinion gear, in an axial direction of the rack bar, a cylindrical rack guide body made of synthetic resin, the tip surface of which is formed with a guide surface that slides against the back surface of the rack bar; a plurality of support portions made of synthetic resin that protrude from an outer peripheral surface of the rack guide body and are movable in a radial direction of the rack guide body; a synthetic resin biasing portion provided for each of the support portions, extending circumferentially from both sides of the support portion in the circumferential direction of the rack guide body, connecting to the rack guide body, and biasing the support portion radially outward of the rack guide body; 、 The support portion is a main protrusion having a support surface protruding from the outer peripheral surface of the rack guide body; a pair of sub-projections provided on both sides of the main projection in the circumferential direction of the rack guide body, the sub-projections having support surfaces projecting from the outer peripheral surface of the rack guide body; . [Effects of the Invention]

[0008] In this invention, each support portion is biased radially outward of the rack guide body by the biasing portion, and supports the rack guide by pressing and sliding against the inner wall of the housing. This allows the rack guide to be accommodated in the housing without any play, preventing the generation of hammering noise. Furthermore, the rack guide body, support portions, and biasing portions are all made of synthetic resin, and the biasing portions extend circumferentially from both sides of the support portions in the circumferential direction of the rack guide body and connect to the rack guide body. This allows these to be integrally molded using the same resin material, reducing the number of parts and labor. Therefore, this invention can be manufactured inexpensively and stably support the rack bar while preventing the generation of hammering noise. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of a gear mechanism 1 of a steering device according to an embodiment of the present invention. [Figure 2] 2(A) and 2(B) are a front view and a side view of the rack guide 30 shown in FIG. [Figure 3] 3(A) and 3(B) are a plan view and a bottom view of the rack guide 30 shown in FIG. [Figure 4] 4(A) and 4(B) are cross-sectional views taken along the lines AA and BB of the rack guide 30 shown in FIG. 3(A). [Figure 5] Figure 5(A) is a view of the rack guide 30 housed in the cylinder case portion 72 of the housing 70 as seen from the bottom side of the gear mechanism 1, and Figure 5(B) is an enlarged view of part C in Figure 5(A). [Figure 6] 6(A) and 6(B) are a front view and a side view of a modified example 30A of the rack guide 30. FIG. [Figure 7] 7(A) and 7(B) are a plan view and a bottom view of a modified example 30A of the rack guide 30. FIG. [Figure 8] 8(A) and 8(B) are a DD cross-sectional view and an EE cross-sectional view of a modified example 30A of the rack guide 30 shown in FIG. 7(A). DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] For convenience of the following explanation, the direction of the axis O2 of the rack bar 20 (the direction of reciprocating movement of the rack bar 20) is defined as the X direction, the direction in which the rack gear 21 presses against the pinion gear 11 is defined as the Z direction, and the direction perpendicular to the X and Z directions is defined as the Y direction, and these directions are appropriately indicated in each drawing.

[0012] FIG. 1 is a schematic cross-sectional view of a gear mechanism 1 of a steering device according to this embodiment.

[0013] The steering device according to this embodiment has a rack-and-pinion gear mechanism 1 that converts the rotational motion of the steering shaft into linear motion and transmits this linear motion to a link mechanism that changes the direction of the wheels. Note that this steering device may or may not be equipped with a power steering mechanism that uses a motor to assist the motion of the pinion gear 11 or rack bar 20.

[0014] As shown in the figure, this gear mechanism 1 includes a pinion shaft 10 on which a pinion gear 11 is formed, a rack bar 20 on which a rack gear 21 that meshes with the pinion gear 11 is formed, a pair of rolling bearings 40 that rotatably support the pinion shaft 10, a rack guide 30 that guides the rack bar 20 that moves back and forth in the X direction as the pinion gear 11 rotates, a housing 70 in which these parts 10 to 40 are incorporated, and a cap 60 that closes the housing 70.

[0015] The pinion shaft 10 is a cylindrical member disposed such that its axis O1 is inclined in the X direction with respect to the Y direction, and a helical gear, for example, is formed on its outer peripheral surface 12 as the pinion gear 11. The pinion gear 11 is accommodated in a pinion gear accommodating chamber 73 provided in the housing 70, and the pinion shaft 10 is supported by the housing 70 via a pair of rolling bearings 40 on both sides of the pinion gear 11 so as to be rotatable about the axis O1. One end 13 of the pinion shaft 10 protrudes outside the pinion gear accommodating chamber 73 from an opening 74 formed in the housing 70 and is connected to a steering shaft (not shown). As a result, the pinion gear 11 rotates in conjunction with the steering shaft, which rotates in response to operation of the steering wheel.

[0016] The rack bar 20 is a cylindrical member arranged along the X direction, and both ends thereof are connected via ball joints (not shown) to a link mechanism that changes the direction of the wheels. The rack gear 21 has multiple teeth aligned along the X direction on the outer circumferential surface of the rack bar 20. The teeth mesh with the teeth of the pinion gear 11 at predetermined meshing positions in the pinion gear accommodating chamber 73 of the housing 70. A back surface 22 of the rack bar 20 (the outer circumferential surface, located opposite the rack gear 21, and having an arc-shaped YZ cross section) is slidably supported by the rack guide 30 in response to the magnitude of the load applied by the rack bar 20 to the rack guide 30. When the pinion shaft 10 rotates together with the steering shaft, the meshing of the pinion gear 11 and the rack gear 21 causes the rack bar 20 to reciprocate in the X direction while being guided by the rack guide 30, thereby swinging the link mechanism. This changes the direction of the wheels in response to the operation of the steering wheel.

[0017] The housing 70 has a cylindrical rack case portion 71 arranged along the X direction, and a cylindrical cylinder case portion 72 protruding from the outer periphery of the rack case portion 71 in the Z direction.

[0018] The rack case portion 71 accommodates the rack bar 20 so that it can move back and forth in the X direction. The rack case portion 71 also has a pinion gear accommodating chamber 73. As described above, the pinion gear accommodating chamber 73 accommodates the pinion gear 11 and a pair of rolling bearings 40 that rotatably hold the pinion shaft 10 so that the pinion gear 11 meshes with the rack gear 21 at a predetermined meshing position. The rack case portion 71 also has an opening 74 that connects the inside and outside of the pinion gear accommodating chamber 73 and is formed toward the steering shaft (not shown). One end 13 of the pinion shaft 10, which is connected to the steering shaft (not shown), protrudes from the opening 74 to the outside of the pinion gear accommodating chamber 73.

[0019] On the other hand, the cylinder case portion 72 is formed integrally with the rack case portion 71 so as to be located on the opposite side of the rack bar 20 from the pinion gear 11, and the interior of the cylinder case portion 72 and the interior of the rack case portion 71 are connected via an opening 75 that faces the pinion gear 11 in the pinion gear accommodating chamber 73. Also, a threaded portion 77 for fixing the cap 60 is formed on an open end 76 of an inner wall surface 78 of this cylinder case portion 72.

[0020] The rack guide 30 is housed in the cylinder case portion 72 in the Z direction with a guide surface 310 that slidably supports the back surface 22 of the rack bar 20 facing the back surface 22 of the rack bar 20, and is positioned on the opposite side of the pinion gear 11 with respect to the rack bar 20 (the back surface 22 side of the rack bar 20 at the meshing position of the pinion gear 11 and the rack gear 21). The detailed structure of this rack guide 30 will be described later.

[0021] The cap 60 has a disk shape that can be fitted into the open end 76 of the cylinder case portion 72, and a threaded portion 62 is formed on the outer periphery of the cap 60. By inserting the rack guide 30 into the cylinder case portion 72 of the housing 70 and screwing the threaded portion 62 of the cap 60 into the threaded portion 77 of the open end 76 of the cylinder case portion 72, the cap 60 is fixed to the open end 76 of the cylinder case portion 72 and the cylinder case portion 72 is closed.

[0022] Next, the detailed structure of the rack guide 30 will be described.

[0023] Figures 2(A) and 2(B) are a front view and a side view of the rack guide 30 shown in Figure 1, and Figures 3(A) and 3(B) are a plan view and a bottom view of the rack guide 30 shown in Figure 1. Also, Figures 4(A) and 4(B) are AA and BB cross-sectional views of the rack guide 30 shown in Figure 3(A).

[0024] As shown in the figure, the rack guide 30 has a cylindrical rack guide main body 31, a pair of support portions 32a, 32b that are provided so as to be movable in the radial direction of the rack guide main body 31, biasing portions 33a, 33b that bias the support portions 32a, 32b radially outward of the rack guide main body 31, and a spring 34.

[0025] The rack guide body 31 has a concave guide surface 310 provided on the tip surface (end surface on the rack bar 20 side) of the rack guide body 31 and sliding against the back surface of the rack bar 20, a pair of accommodating portions 312a, 312b provided on the outer peripheral surface 311 of the rack guide body 31 and accommodating the support portions 32a, 32b together with the biasing portions 33a, 33b, respectively, and a spring guide 313 for accommodating the spring 34.

[0026] A sliding area 314 of the guide surface 310 against the back surface of the rack bar 20 is formed with a number of recesses 315 that function as grease reservoirs.

[0027] The accommodation portions 312a and 312b are formed on the outer peripheral surface 311 of the rack guide main body 31 so as to cut out the outer peripheral surface 311 on both sides in a direction (Y direction) perpendicular to the sliding direction (X direction) between the guide surface 310 and the rack bar 20 and to the direction of the axis O3 (Z direction) of the rack guide 30. The accommodation portion 312a accommodates the support portion 32a together with the urging portion 33a, and the accommodation portion 312b accommodates the support portion 32b together with the urging portion 33b.

[0028] The spring guide 313 is a cylindrical hole having an opening on the rear end face (the end face on the cap 60 side), and the spring 34 is housed inside this cylindrical hole.

[0029] The support portions 32a and 32b are arranged on both sides of the rack guide main body 31 in a direction (Y direction) perpendicular to the sliding direction (X direction) between the guide surface 310 and the rack bar and the direction of the axis O3 (Z direction) of the rack guide 30 (see FIG. 3(B)), and are housed in housing portions 312a and 312b together with the biasing portions 33a and 33b, respectively. Each of the support portions 32a and 32b has a main protrusion 320 and a pair of sub-protrusions 321a and 321b arranged on both sides of the main protrusion 320 in the circumferential direction of the rack guide main body 31.

[0030] The main protrusion 320 has a support surface 323 that protrudes from the outer peripheral surface 311 of the rack guide main body 31, and this support surface 323 slides on the inner wall surface 78 of the cylinder case portion 72 of the housing 70 in the axial O3 direction (Z direction) of the rack guide main body 31. As a result, the rack guide 30 is housed in the cylinder case portion 72 without any backlash and can move in the axial O3 direction of the rack guide main body 31.

[0031] The sub-projections 321a and 321b have support surfaces 324 that protrude from the outer peripheral surface 311 of the rack guide body 31 and are located radially inward of the support surface 323 of the main projection 320. 0When a radial load is applied to the main protrusion 320 and the main protrusion 320 moves radially inward, the support surfaces 324 of the sub-protrusions 321a, 321b come into contact with the inner wall surface 78 of the cylinder case portion 72 of the housing 70 and support the radial load together with the main protrusion 320.

[0032] The urging portions 33a are leaf spring-like members that extend circumferentially from both sides of the support portion 32a in the circumferential direction of the rack guide main body 31 and are connected to the rack guide main body 31, and the urging portions 33b are leaf spring-like members that extend circumferentially from both sides of the support portion 32b in the circumferential direction of the rack guide main body 31 and are connected to the rack guide main body 31. The biasing portions 33a, 33b include first leaf spring portions 330a, 330b that extend circumferentially from the main protrusion 320 on both sides and connect to the sub-protrusions 321a, 321b, a second leaf spring portion 331a that extends circumferentially and radially from the sub-protrusion 321a toward the radially outer end portion 317a of the side wall 316a of the accommodating portions 312a, 312b and connects to the rack guide main body 31, and a second leaf spring portion 331b that extends circumferentially and radially from the sub-protrusion 321b toward the radially outer end portion 317b of the side wall 316b of the accommodating portions 312a, 312b and connects to the rack guide main body 31.

[0033] The rack guide body 31, support portions 32a, 32b (main protrusion portion 320, sub-protrusion portions 321a, 321b), and biasing portions 33a, 33b (first leaf spring portions 330a, 330b, second leaf spring portions 331a, 331b) are integrally molded using synthetic resins such as polyethylene terephthalate, polybutylene terephthalate, polyamide, polyphenylene sulfide, and polyacetal that are fiber-reinforced with glass or the like.

[0034] The spring 34 is a coil spring, a leaf spring, or the like, and is disposed within a spring guide 313 of the rack guide main body 31. The spring 34 has a natural length that is longer than the height (depth) of the spring guide 313, and one end of the spring 34 protrudes from an opening in the spring guide 313 and abuts against the cap 60. As a result, the cap 60 functions as a spring seat for the spring 34, and the spring 34 biases the rack guide main body 31 in a direction that pushes it toward the rack bar 20, thereby pressing the guide surface 310 against the back surface 22 of the rack bar 20. This presses the rack gear 21 against the pinion gear 11, preventing separation of the teeth at the meshing position of the rack gear 21 and the pinion gear 11.

[0035] Figure 5(A) is a view of the rack guide 30 housed in the cylinder case portion 72 of the housing 70 as seen from the bottom side of the gear mechanism 1, and Figure 5(B) is an enlarged view of part C in Figure 5(A).

[0036] 5(A) and 5(B), the support surfaces 323 of the main protrusions 320 of the support portions 32a and 32b, which are urged radially outward of the rack guide body 31 by the first leaf spring portions 330a and 330b of the urging portions 33a and 33b, protrude from the outer peripheral surface 311 of the rack guide body 31 and slide against the inner wall surface 78 of the cylinder case portion 72 of the housing 70. As a result, the rack guide 30 is accommodated in the cylinder case portion 72 without any backlash and is movable in the direction of the axis O3.

[0037] Furthermore, the support surfaces 324 of the sub-projections 321a, 321b, which are biased radially outward of the rack guide main body 31 by the first leaf spring portions 330a, 330b and second leaf spring portions 331a, 331b of the biasing portions 33a, 33b and which protrude from the outer peripheral surface 311 of the rack guide main body 31 but are positioned radially inward of the support surface 323 of the main projection 320, come into contact with the inner wall surface 78 of the cylinder case portion 72 of the housing 70 and support the radial load together with the main projection 320 when a large radial load is applied to the rack guide 30 and this load causes the main projection 320 to move radially inward.

[0038] One embodiment of the present invention has been described above.

[0039] In this embodiment, the support portions 32a, 32b, which are biased radially outward of the rack guide main body 31 by the biasing portions 33a, 33b, press and slide against the inner wall surface 78 of the cylinder case portion 72 of the housing 70, thereby supporting the rack guide 30. This allows the rack guide 30 to be housed in the housing 70 without any play, preventing the generation of hammering noise. Furthermore, the rack guide main body 31, the support portions 32a, 32b, and the biasing portions 33a, 33b are all made of synthetic resin. The biasing portions 33a, 33b extend circumferentially from both sides of the support portions 32a, 32b in the circumferential direction of the rack guide main body 31 and connect to the rack guide main body 31. This allows these to be integrally molded using the same resin material, reducing the number of parts and the number of steps. Therefore, this embodiment allows for inexpensive manufacturing, prevents the generation of hammering noise, and stably supports the rack bar 20.

[0040] In addition, in this embodiment, the support portions 32a, 32b include a main protrusion portion 320 having a support surface 323 protruding from the outer peripheral surface 311 of the rack guide body 31, and a pair of sub-protrusion portions 321a, 321b provided on both sides of the main protrusion portion 320 in the circumferential direction of the rack guide body 31 and having support surfaces 324 that protrude from the outer peripheral surface 311 of the rack guide body 31 but are located radially inward from the support surface 323 of the main protrusion portion 320. Therefore, the support surfaces 323 of the main protrusions 320 protrude from the outer peripheral surface 311 of the rack guide main body 31 and slide against the inner wall surface 78 of the cylinder case portion 72 of the housing 70, thereby supporting the rack guide 30, and in the event that a large load is applied to the rack guide 30 in the radial direction and the main protrusions 320 move radially inward due to this load, the support surfaces 324 of the sub-protrusions 321 a, 321 b come into contact with the inner wall surface 78 of the cylinder case portion 72 of the housing 70 and support the radial load together with the main protrusions 320. Therefore, according to this embodiment, even when a large load is applied radially to the rack guide 30, it is possible to support the rack bar 20 while preventing the generation of hitting sounds.

[0041] In the present embodiment, the urging portions 33a, 33b include first leaf spring portions 330a, 330b that extend circumferentially from both sides of the main protrusion 320 and connect to the sub-protrusions 321a, 321b in the circumferential direction of the rack guide body 31, and second leaf spring portions 331a, 331b that extend circumferentially and radially from the sub-protrusions 321a, 321b toward radially outer ends 317a, 317b of the side walls 316a, 316b of the accommodating portions 312a, 312b and connect to the rack guide body 31. This allows the main protrusion 320 and the sub-protrusions 321a, 321b to move radially independently, and when a large load is applied to the rack guide 30 in the radial direction, the main protrusion 320 moves radially following the main protrusion 320, while the urging portions 33a, 33b can absorb the load. Therefore, according to this embodiment, even when a large load is applied to the rack guide 30 in the radial direction, the occurrence of hitting noise can be more effectively prevented.

[0042] In the present embodiment, the rack guide body 31 has accommodation portions 312a, 312b that are formed on the outer peripheral surface 311 of the rack guide body 31 and that accommodate the support portions 32a, 32b together with the urging portions 33a, 33b. This makes it possible to prevent the rack guide 30 from becoming large due to the support portions 32a, 32b and the urging portions 33a, 33b.

[0043] Furthermore, in this embodiment, the support portions 32a, 32b are arranged on both sides of the rack guide main body 31 in a direction (Y direction) perpendicular to the sliding direction (X direction) between the guide surface 310 and the rack bar 20. Therefore, according to this embodiment, when the rotational motion of the pinion shaft 10 is converted into linear motion in the axial O2 direction (X direction) of the rack bar 20, the load applied to the rack bar 20 in the direction (Y direction) perpendicular to the sliding direction (X direction) between the guide surface 310 and the rack bar 20 and the axial O3 direction (Z direction) of the rack guide 30 can be supported by the support portions 32a, 32b. Therefore, it is possible to more effectively prevent the rack guide 30 from rattling inside the cylinder case portion 72.

[0044] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the gist of the present invention.

[0045] For example, in the above embodiment, two support portions 32a, 32b are provided together with the biasing portions 33a, 33b, but the present invention is not limited to this. Three or more support portions may be provided together with the biasing portions. In this case, it is preferable to arrange at least one support portion in the direction (Y direction) perpendicular to the sliding direction (X direction) between the guide surface 310 and the rack bar 20 of the rack guide body 31.

[0046] In the above embodiment, the support portions 32a, 32b are configured by the main protrusion 320 having a support surface 323 protruding from the outer peripheral surface 311 of the rack guide body 31, and a pair of sub-protrusions 321a, 321b provided on both sides of the main protrusion 320 in the circumferential direction of the rack guide body 31 and having support surfaces 324 protruding from the outer peripheral surface 311 of the rack guide body 31 but positioned radially inward from the support surface 323 of the main protrusion 320. However, the present invention is not limited to this. The sub-protrusions 321a, 321b have lower rigidity than the main protrusion 320, and therefore, when a large radial load is applied to the rack guide 30, they may reinforce the main protrusion 320 and support the load together with the main protrusion 320. The rigidity of the main protrusion 320 and the sub-protrusions 321a, 321b can be adjusted, for example, by changing the elastic force of the first leaf spring portions 330a, 330b and the second leaf spring portions 331a, 331b, specifically by changing at least one of the length, width, thickness, and size of the R portion of the first leaf spring portions 330a, 330b and the second leaf spring portions 331a, 331b.

[0047] In the above embodiment, the support portions 32a, 32b are configured by the main protrusion 320 and a pair of sub-protrusions 321a, 321b arranged on both sides of the main protrusion 320 in the circumferential direction of the rack guide body 31, but the present invention is not limited to this. One or both of the sub-protrusions 321a, 321b may be omitted.

[0048] Furthermore, in the above embodiment, in addition to the support portions 32a and 32b, support portions that slide against the inner wall surface 78 of the cylinder case portion 72 of the housing 70 may be provided on the outer peripheral surface 311 of the rack guide main body 31 on both sides of the sliding direction (X direction) between the guide surface 310 and the rack bar 20 so as to be movable in the radial direction of the rack guide main body 31.

[0049] Figures 6(A) and 6(B) are a front view and a side view of a modified example 30A of the rack guide 30, and Figures 7(A) and 7(B) are a plan view and a bottom view of the modified example 30A of the rack guide 30. Also, Figures 8(A) and 8(B) are a DD cross-sectional view and an EE cross-sectional view of the modified example 30A of the rack guide 30 shown in Figure 7(A).

[0050] The rack guide 30A shown in FIGS. 6 to 8 differs from the rack guide 30 shown in FIGS. 2 to 4 in that a rack guide body 31A is used instead of the rack guide body 31, and that a pair of support portions 35a, 35b are provided so as to be movable in the radial direction of the rack guide body 31A, and that the support portions 35a, 35b are provided so as to be movable in the radial direction of the rack guide body 31A. A The other configuration is the same as that of the rack guide 30.

[0051] The rack guide body 31A differs from the rack guide body 31 in that a pair of accommodating portions 318a, 318b are added to the outer peripheral surface 311 of the rack guide body 31A and accommodate the support portions 35a, 35b together with the biasing portions 36a, 36b, respectively. The other configurations are the same as those of the rack guide body 31.

[0052] The accommodation portions 318a and 318b are formed on the outer peripheral surface 311 of the rack guide main body 31A so as to cut out the outer peripheral surface 311 on both sides in the sliding direction (X direction) between the guide surface 310 and the rack bar 20. The accommodation portion 318a accommodates the support portion 35a together with the urging portion 36a, and the accommodation portion 318b accommodates the support portion 35b together with the urging portion 36b.

[0053] The support portions 35a and 35b are arranged on both sides of the rack guide body 31A in the sliding direction (X direction) between the guide surface 310 and the rack bar, and are housed in the housing portions 318a and 318b together with the biasing portions 36a and 36b, respectively.

[0054] The biasing portion 36a is a leaf spring-like member that extends from the support portion 35a toward the bottom surface 319a of the accommodating portion 318a in the axial O3 direction of the rack guide main body 31A and is connected to the rack guide main body 31A, and the biasing portion 36b is a leaf spring-like member that extends from the support portion 35b toward the bottom surface 319b of the accommodating portion 318b in the axial O3 direction of the rack guide main body 31A and is connected to the rack guide main body 31A.

[0055] According to the rack guide 30A configured as described above, the support portions 35a, 35b, which are biased radially outward of the rack guide main body 31A by the biasing portions 36a, 36b, press and slide against the inner wall surfaces 78 of the cylinder case portion 72 of the housing 70 on both sides of the rack guide main body 31A in the sliding direction (X direction) between the guide surface 310 and the rack bar 20. As a result, the rack guide 30A is housed in the housing 70 without any backlash in the sliding direction (X direction) between the guide surface 310 and the rack bar 20, and even when a load is applied to the rack guide 30A in the sliding direction (X direction) between the guide surface 310 and the rack bar 20, the generation of hitting sounds can be more effectively prevented. Other effects are the same as those of the rack guide 30 shown in FIGS. 2 to 4.

[0056] In the rack guide 30 according to the above embodiment, the biasing portions 33a, 33b are leaf spring-like members that extend circumferentially from both sides of the support portions 32a, 32b in the circumferential direction of the rack guide main body 31 and connect to the rack guide main body 31, but the present invention is not limited to this. The biasing portions 33a, 33b may be spring-like members of any shape as long as they are spring-like members that can bias the support portions 32a, 32b radially outward of the rack guide main body 31. Similarly, in the modified example 30A of the rack guide 30 according to the above embodiment, the biasing portions 36a, 36b are leaf spring-like members that extend from the support portions 35a, 35b toward the bottom surfaces 319a, 319b of the accommodation portions 318a, 318b in the axial O3 direction of the rack guide main body 31A and connect to the rack guide main body 31A, but the present invention is not limited to this. The biasing portions 36a, 36b may be spring-like members that can bias the support portions 35a, 35b radially outward of the rack guide main body 31A. AAny shape of spring-like member may be used as long as it can bias the bearing 10 radially outward.

[0057] Furthermore, although the above embodiment has been described as an example of application to a vehicle steering device, the present invention is not limited to vehicle steering devices and can be widely applied to devices that utilize a rack-and-pinion gear mechanism, such as a focusing mechanism for optical equipment. [Explanation of symbols]

[0058] 1: Gear mechanism 10: Pinion shaft 11: Pinion gear 12: Outer surface of pinion shaft 10 13: End of pinion shaft 10 20: Rack bar 21: Rack gear 22: Back of rack bar 20 30: Rack guide 31, 31A: Rack guide body 32a, 32b, 35a, 35b: Support part 33a, 33b, 36a, 36b: Biasing section 34: Spring 40: Rolling bearing 60: Cap 62: Threaded part of cap 60 70: Housing 71: Rack case 72: Cylinder case part 73: Pinion gear housing 74, 75: Openings 76: Open end of cylinder case 72 77: Threaded portion of cylinder case portion 72 78: Inner wall surface of cylinder case portion 72 310: Guide surface 311: Outer surface of rack guide body 31 312a, 312b, 318a, 318b: storage section 313: Spring guide 314: Sliding area of ​​guide surface 310 315: Recess 316a, 316b: side walls of the storage sections 312a, 312b 319a, 319b: bottom surfaces of the storage sections 318a, 318b 320: Main protrusion 321a, 321b: Sub-protrusions 323, 324: Support surface 3 1 7a, 317b: radially outer ends of side walls 316a, 316b 330a, 330b: first leaf spring part 331a, 331b: second leaf spring part

Claims

1. A rack guide slidably supports a rack bar, on which a rack gear that meshes with a pinion gear is formed, from an opposite side of the rack gear, and guides the rack bar, which moves in accordance with rotation of the pinion gear, in an axial direction of the rack bar, a cylindrical rack guide body made of synthetic resin, the tip surface of which is formed with a guide surface that slides against the back surface of the rack bar; a plurality of support portions made of synthetic resin that protrude from an outer peripheral surface of the rack guide body and are movable in a radial direction of the rack guide body; a synthetic resin biasing portion provided for each of the support portions, extending circumferentially from both sides of the support portion in the circumferential direction of the rack guide body to connect to the rack guide body, and biasing the support portion radially outward of the rack guide body, The support portion is a main protrusion having a support surface protruding from the outer peripheral surface of the rack guide body; a pair of sub-projections provided on both sides of the main projection in the circumferential direction of the rack guide body, the sub-projections having support surfaces projecting from the outer peripheral surface of the rack guide body; A rack guide characterized by:

2. The rack guide according to claim 1, The support portion is The rack guide body has a axial direction and a direction perpendicular to the sliding direction between the guide surface and the rack bar. A rack guide characterized by:

3. The rack guide according to claim 1 or 2, The biasing portion is a pair of first spring portions connecting the main protrusion and each of the pair of sub protrusions along the circumferential direction of the rack guide body; a pair of second spring portions that connect the pair of sub-projections and the rack guide body along the circumferential direction of the rack guide body; A rack guide characterized by:

4. The rack guide according to any one of claims 1 to 3, The rack guide body is a receiving portion formed on an outer peripheral surface of the rack guide body, the receiving portion receiving the support portion together with the biasing portion; A rack guide characterized by:

5. A gear mechanism that changes the direction of travel of a moving object in response to the rotation of a steering wheel, a pinion gear that rotates in response to rotation of the steering wheel; a rack bar having a rack gear that meshes with the pinion gear, the rack bar moving back and forth in response to rotation of the pinion gear due to the meshing of the pinion gear with the rack gear, thereby changing the direction of the wheels of the moving body; a rack guide according to any one of claims 1 to 4, which supports the rack bar so as to be movable in an axial direction of the rack bar; a housing that accommodates the rack guide so as to be movable in the axial direction of the rack guide; A gear mechanism characterized by:

Images