Steering device

Abstract

To provide a steering device capable of reducing sliding resistance between a rack shaft and a rack guide.SOLUTION: The steering device includes a rack shaft, a first pinion shaft, and a rack guide. The rack guide includes a main body and a lubricating sheet. The main body portion has a fixing surface portion to which the lubricating sheet is fixed, and a pair of protruding portions that are positioned away from the fixing surface portion toward the X1 side and the X2 side and protrude toward the Y1 side. Each of the pair of convex portions continuously extends along the Z direction and faces the end surface of the lubricating sheet in the X direction over the entire region in the Z direction.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present disclosure relates to a steering device. [Background technology]

[0002] Patent Document 1 discloses a steering device including a rack shaft extending in the axial direction and a rack guide that supports the back surface of the rack shaft. The rack guide has a cylindrical main body and a lubricating sheet attached to the rack shaft side of the main body. A lubricant such as grease is applied between the lubricating sheet and the back surface of the rack shaft to reduce sliding resistance. That is, the lubricating sheet abuts (slidingly contacts) against the back surface of the rack shaft via the lubricant. As a result, when the rack shaft reciprocates in the axial direction due to steering of the steering wheel, the lubricating sheet slides against the back surface of the rack shaft via the lubricant.

[0003] In addition, in Patent Document 1, in order to reduce the sliding resistance between the rack shaft and the lubricating sheet, a recess is provided on the surface of the lubricating sheet facing the rack shaft, recessed toward the main body and extending in the axial direction. When the lubricating sheet abuts against the rack shaft, the rack shaft seals the recess, allowing lubricant to be contained within the recess. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-245828 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the recesses of the lubricating sheet according to Patent Document 1 have open (open) axial ends, the lubricant in the recesses may flow out from the ends, making it difficult for the lubricant to remain in the recesses.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide a steering device that can further reduce the sliding resistance between the rack shaft and the rack guide. [Means for solving the problem]

[0007] In order to achieve the above object, a steering device according to one aspect of the present disclosure includes: a rack shaft that extends in a first direction, has rack teeth provided on a side surface on one side in a second direction intersecting the first direction, and has an abutment portion provided on a side surface on the other side in the second direction opposite to the rack teeth; a pinion shaft that is located on one side in the second direction with respect to the rack teeth, has pinion teeth that mesh with the rack teeth on its outer periphery, and is rotatable around an axis of a rotation shaft; and a rack guide that is located on the other side in the second direction with respect to the abutment portion of the rack shaft, and abuts on the abutment portion from the other side in the second direction to support the rack shaft, wherein the rack guide is the lubricating sheet is fixed to the first surface portion and abuts against the abutment portion, the first surface portion having a fixed surface portion to which the lubricating sheet is fixed, and a pair of protrusions positioned at a distance from the fixed surface portion on one side and the other side in the first direction and protruding to one side in the second direction, wherein when a direction intersecting the first direction and the second direction is defined as a third direction, each of the pair of protrusions extends continuously along the third direction, faces an end face of the lubricating sheet in the first direction over the entire area in the third direction, and is disposed at a distance in the first direction from the end face of the lubricating sheet in the first direction.

[0008] As mentioned above, in Patent Document 1, the recess of the lubricating sheet is open at one end in the axial direction, so there is a possibility that the lubricant in the recess will flow out from that end, making it difficult for the lubricant to remain in the recess.

[0009] In contrast, the rack guide according to the present disclosure has a convex portion that faces the end face of the lubricating sheet in the first direction over the entire area in the third direction. The convex portion is disposed at a distance in the first direction from the end face of the lubricating sheet. As a result, a recessed groove is formed between the end face of the lubricating sheet and the convex portion. Even if a lubricant is applied between the lubricating sheet and the rack shaft and the lubricant flows out from between the lubricating sheet and the rack shaft, the lubricant collects in the recessed groove, thereby preventing the lubricant from leaking out. Furthermore, the lubricant that has collected in the recessed groove may flow again between the lubricating sheet and the rack shaft. As described above, according to the present disclosure, it is possible to provide a steering device that can further reduce the sliding resistance between the rack shaft and the rack guide.

[0010] In a preferred embodiment, the apex of the convex portion on one side in the second direction is located closer to the other side in the second direction than the surface of the lubricating sheet on one side in the second direction, thereby creating a gap between the apex of the convex portion and the rack shaft, thereby preventing the apex of the convex portion from interfering with the rack shaft when the rack shaft reciprocates in the first direction.

[0011] In a preferred embodiment, the first surface portion has a recess between the fixing surface portion and the protrusion portion that is recessed toward the other side in the second direction relative to the fixing surface portion. This results in a deeper recess than the recessed groove. In other words, a larger volume of the recess can be obtained, allowing a larger amount of lubricant to be stored in the recess.

[0012] In a preferred embodiment, the rack shaft is made of metal, the protrusions are made of rubber or resin, and the apex of the protrusions on one side in the second direction is positioned at the same position in the second direction as the surface of the lubricating sheet on one side in the second direction. This allows for higher protrusions to be provided, and a larger amount of lubricant can be stored in the recesses formed by the protrusions. Furthermore, because the protrusions are made of rubber or resin, damage to the protrusions is suppressed even if the protrusions interfere with the rack shaft reciprocating in the first direction.

[0013] A steering device according to one aspect of the present disclosure includes: a rack shaft that extends in a first direction, has rack teeth provided on a side surface on one side in a second direction intersecting the first direction, and has an abutment portion provided on a side surface on the other side in the second direction opposite the rack teeth; a pinion shaft that is located on one side in the second direction with respect to the rack teeth, has pinion teeth that mesh with the rack teeth on its outer periphery, and is rotatable around an axis of a rotation shaft; and a rack guide that is located on the other side in the second direction with respect to the abutment portion of the rack shaft, and supports the rack shaft by abutting on the abutment portion from the other side in the second direction, wherein the rack guide has: a main body portion that is provided with a first surface portion on one side in the second direction; a lubricating sheet that is fixed to the first surface portion and abuts on the abutment portion; and a lubricant retaining member that is fixed to the first surface portion, abuts on the abutment portion, and is capable of absorbing and retaining lubricant.

[0014] According to this, by applying the lubricant held in the lubricant holding member to the rack shaft, the lubricant in the lubricant holding member can flow between the lubricating sheet and the rack shaft. Also, since the lubricant that flows out from between the lubricating sheet and the rack shaft is absorbed by the lubricant holding member, the outflow of the lubricant to the outside is further suppressed. [Effects of the Invention]

[0015] According to the present disclosure, it is possible to provide a steering device that can further reduce the sliding resistance between the rack shaft and the rack guide. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of a steering device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing a part of the steering device according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view of FIG. [Figure 4A] FIG. 4A is an exploded perspective view of the rack guide according to the first embodiment. [Figure 4B]FIG. 4B is a perspective view of the rack guide according to the first embodiment. [Figure 5A] FIG. 5A is a side view of the rack guide according to the first embodiment. [Figure 5B] FIG. 5B is a front view of the rack guide according to the first embodiment. [Figure 5C] FIG. 5C is a cross-sectional view taken along line VC-VC in FIG. 5B. [Figure 6] FIG. 6 is a schematic diagram showing an enlarged view of a part of the rack guide and the rack shaft according to the first embodiment. [Figure 7A] FIG. 7A is a schematic enlarged view of a portion of the rack guide and rack shaft according to the first embodiment, illustrating the initial stage in which the lubricant flows out from between the rack shaft and the lubricating sheet into the recessed groove. [Figure 7B] FIG. 7B is a schematic enlarged view of a portion of the rack guide and rack shaft according to the first embodiment, showing the intermediate stage in which the lubricant flows out into the recessed groove from between the rack shaft and the lubricating sheet. [Figure 7C] FIG. 7C is a schematic enlarged view of a portion of the rack guide and rack shaft according to the first embodiment, showing a later stage in which the lubricant flows out into the recessed groove from between the rack shaft and the lubricating sheet. [Figure 8A] FIG. 8A is a schematic diagram showing the force applied to the lubricating sheet from the rack shaft in the first embodiment. [Figure 8B] FIG. 8B is a schematic diagram showing the force applied to the lubricating sheet from the rack shaft in the comparative example. [Figure 9A] FIG. 9A is a side view of the rack guide according to the second embodiment. [Figure 9B] FIG. 9B is a front view of the rack guide according to the second embodiment. [Figure 9C] FIG. 9C is a cross-sectional view taken along line IXC-IXC in FIG. 9B. [Figure 10] FIG. 10 is a schematic diagram showing an enlarged view of a part of the rack guide and the rack shaft according to the second embodiment. [Figure 11] FIG. 11 is a schematic diagram showing an enlarged view of a part of the rack guide and rack shaft according to the third embodiment. [Figure 12] FIG. 12 is a schematic diagram showing an enlarged view of a part of the rack guide and the rack shaft according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the following detailed description of the invention (hereinafter referred to as the embodiment). Furthermore, the components in the following embodiment include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiment can be combined as appropriate. Note that in the drawings, the X direction indicates the first direction, the Y direction indicates the second direction, and the Z direction indicates the third direction. The Y direction intersects with the X direction. The Z direction intersects with the X and Y directions. The X1 side is one side of the first direction, and the X2 side is the other side of the first direction. The Y1 side is one side of the second direction, and the Y2 side is the other side of the second direction. The Z1 side is one side of the third direction, and the Z2 side is the other side of the third direction.

[0018] [First embodiment] First, a first embodiment will be described. FIG. 1 is a schematic diagram of a steering device according to the first embodiment.

[0019] 1, steering device 80 includes, in the order in which force applied by an operator is transmitted, a steering wheel 81, a steering shaft 82, a universal joint 84, an intermediate shaft 85, a universal joint 86, a stub shaft 87, a steering gear 100, and a tie rod 89. Steering device 80 also includes a control device (hereinafter referred to as an ECU (Electronic Control Unit)) 99, a torque sensor 10, and an electric motor 102. A vehicle speed sensor 101 is provided in the vehicle and outputs a vehicle speed signal V to ECU 99 via CAN (Controller Area Network) communication.

[0020] One end of the steering shaft 82 is connected to the steering wheel 81, and the other end is connected to a universal joint 84. One end of the intermediate shaft 85 is connected to the universal joint 84, and the other end is connected to a universal joint 86. One end of the stub shaft 87 is connected to the universal joint 86, and the other end is connected to the first pinion shaft 2. The torque sensor 10 is attached to the stub shaft 87.

[0021] The torque sensor 10 detects the rotational torque transmitted between the stub shaft 87 and the first pinion shaft 2 .

[0022] The steering gear 100 includes a first pinion shaft 2, a rack shaft 3, and a second pinion shaft 4. The first pinion shaft 2 is connected to a stub shaft 87 via a torsion bar. The rack shaft 3 meshes with the first pinion shaft 2 and the second pinion shaft 4.

[0023] An electric motor 102 is connected to the second pinion shaft 4 via a worm reduction gear. The second pinion shaft 4 rotates by a driving force transmitted from the electric motor 102. The electric motor 102 rotates the second pinion shaft 4 via the worm reduction gear. The electric motor 102 is, for example, a brushless motor, but may also be a motor equipped with brushes (sliders) and a commutator (commutator).

[0024] The steering gear 100 converts the rotational motion transmitted to the first pinion shaft 2 and the second pinion shaft 4 into linear motion by the rack shaft 3. The steering device 80 according to this embodiment is of a dual pinion assist type in which the rack shaft 3 performs linear motion by the rotational motion transmitted from the first pinion shaft 2 and the second pinion shaft 4. A tie rod 89 is connected to the rack shaft 3. In other words, the steering device 80 is a rack-and-pinion type electric power steering device.

[0025] The torque sensor 10 detects the steering force of the driver transmitted to the steering shaft 82 via the steering wheel 81 as a steering torque. The vehicle speed sensor 101 detects the traveling speed (vehicle speed) of the vehicle on which the steering device 80 is mounted. The electric motor 102, the torque sensor 10, and the vehicle speed sensor 101 are electrically connected to the ECU 99.

[0026] The ECU 99 controls the operation of the electric motor 102. The ECU 99 also acquires signals from the torque sensor 10 and the vehicle speed sensor 101. That is, the ECU 99 acquires the steering torque T from the torque sensor 10 and the vehicle speed signal V from the vehicle speed sensor 101. When the ignition switch 103 is in the on state, the ECU 99 is supplied with power from a power supply device (for example, an on-board battery) 104. The ECU 99 calculates an assist steering command value of the assist command based on the steering torque T and the vehicle speed signal V. Then, the ECU 99 adjusts the power value S to be supplied to the electric motor 102 based on the calculated assist steering command value. The ECU 99 acquires, as operation information R, information on the induced voltage from the electric motor 102 or information output from a rotation detection device such as a resolver provided in the electric motor 102.

[0027] The steering force of the operator (driver) input to the steering wheel 81 is transmitted to the first pinion shaft 2. The steering force transmitted to the first pinion shaft 2 is transmitted to the tie rod 89 via the steering gear 100, displacing the wheels.

[0028] Furthermore, the steering force input by the operator to the steering wheel 81 is transmitted to a torque sensor 10 arranged in a steering force transmission path from the steering wheel 81 to the first pinion shaft 2. At this time, the ECU 99 acquires the steering torque T from the torque sensor 10 and acquires a vehicle speed signal V from a vehicle speed sensor 101. Then, the ECU 99 controls the operation of an electric motor 102. The auxiliary steering torque generated by the electric motor 102 is transmitted to the second pinion shaft 4.

[0029] The auxiliary steering torque transmitted to the second pinion shaft 4 is transmitted to the tie rod 89 via the steering gear 100, displacing the wheels. That is, the steering device 80 displaces the wheels using not only the steering force of the operator transmitted to the rack shaft 3 via the first pinion shaft 2, but also the auxiliary steering torque of the electric motor 102 transmitted to the rack shaft 3 via the second pinion shaft 4.

[0030] 1, the steering device 80 is of a dual pinion type in which an assist force is applied to the first pinion shaft 2, but is not limited to this. The steering device 80 may be, for example, an electric power steering device of a column assist type in which an assist force is applied to the steering shaft 82, or a single pinion assist type in which an assist force is applied to the first pinion shaft 2. The steering device 80 may also be an electric power steering device of a rack assist type in which an assist force is applied to the rack shaft 3 without going through a pinion shaft, such as a ball screw type in which an assist force is applied to the rack shaft 3 by a ball screw.

[0031] Fig. 2 is a perspective view showing a part of the steering device according to the first embodiment, and Fig. 3 is a cross-sectional view of Fig. 2.

[0032] As shown in FIGS. 2 and 3, the steering device 80 includes a rack shaft 3, a first pinion shaft (pinion shaft) 2, and a rack guide 5.

[0033] 2 and 3, the rack shaft 3 extends in the X direction (first direction). The rack shaft 3 has rack teeth 31 on its side surface on the Y1 side, and has a contact portion 35 on its side surface on the Y2 side opposite the rack teeth 31. The rack teeth 31 have multiple teeth arranged at equal intervals in the X direction.

[0034] The rack shaft 3 is housed inside the inner surface 30a of the rack housing 30. Therefore, the rack shaft 3 is capable of moving relative to the rack housing 30 in the X direction.

[0035] The first pinion shaft 2 is located on the Y1 side of the rack teeth 31. The first pinion shaft 2 is rotatable about the rotation axis AX. That is, when the steering wheel 81 (see FIG. 1) is rotated, the first pinion shaft 2 also rotates about the rotation axis AX. Specifically, the first pinion shaft 2 has a rotatable shaft 23 on the inner periphery of the housing 22. First pinion teeth 21 are provided on the outer periphery of the shaft 23. The first pinion teeth 21 mesh with the rack teeth 31. Therefore, when the first pinion shaft 2 rotates, the rack shaft 3 moves linearly in the X direction.

[0036] The rack guide 5 is located on the Y2 side of the contact portion 35 of the rack shaft 3. The rack guide 5 supports the rack shaft 3 by contacting the contact portion 35 from the Y2 side.

[0037] As shown in FIG. 3 , a through-hole 32 is provided in a portion of the rack housing 30 on the Y2 side of the rack shaft 3. The through-hole 32 penetrates the rack housing 30 in the Y direction. A sealing member 34, a coil spring 33, and a rack guide 5 are inserted into the through-hole 32. The sealing member 34 is fixed to the inner wall of the through-hole 32. The rack guide 5 is movable in the Y direction while inserted into the through-hole 32. The coil spring 33 is disposed between the sealing member 34 and the rack guide 5 while being biased. The rack guide 5 is pressed toward the Y1 side by the biasing force of the coil spring 33. As a result, the lubricating sheet 52 of the rack guide 5 comes into contact with the contact portion 35 of the rack shaft 3. More specifically, as the rack shaft 3 moves in the X direction, the lubricating sheet 52 of the rack guide 5 comes into sliding contact with the contact portion 35 of the rack shaft 3.

[0038] Fig. 4A is an exploded perspective view of the rack guide according to the first embodiment. Fig. 4B is a perspective view of the rack guide according to the first embodiment. Fig. 5A is a side view of the rack guide according to the first embodiment. Fig. 5B is a front view of the rack guide according to the first embodiment. Fig. 6 is a schematic enlarged view of a portion of the rack guide and rack shaft according to the first embodiment.

[0039] As shown in FIGS. 4A to 6, the rack guide 5 includes a main body 51 and a lubricating sheet 52. The main body 51 has a generally cylindrical shape extending in the Y direction. The Y1-side surface of the rack guide 5 is made up of a first surface 511 and flat surfaces 516 and 516A. The flat surfaces 516 and 516A extend along the X direction. The first surface 511 is provided between the flat surface 516 and the flat surface 516A. The first surface 511 includes a fixing surface 512 and a protrusion 510.

[0040] 4A and 5B, the protrusion 510 includes a protrusion 513 on the X1 side and a protrusion 514 on the X2 side. When viewed from the Y direction, the protrusions 513 and 514 are each arc-shaped and are spaced apart in the X direction. The protrusion 513 is located on the X1 side, and the protrusion 514 is located on the X2 side.

[0041] As shown in FIGS. 5A and 5B, when viewed from the X1 side, the protrusion 513 extends continuously in the Z direction from the end 513a to the end 513b. The protrusion 513 is formed in an arc shape that protrudes toward the Y2 side. The protrusion 514 is also formed in an arc shape that is recessed toward the Y2 side. The protrusion 514 extends continuously in the Z direction from the end 514a to the end 514b. In this way, the protrusions 513 and 514 form a pair of protrusions 510 that protrude toward the Y1 side. The protrusions 513 and 514 face the end face of the lubricating sheet 52 in the X direction over the entire area in the Z direction.

[0042] As shown in FIG. 4A , a fixing surface portion 512 is provided between the protrusions 513 and 514. The fixing surface portion 512 has a concave shape recessed toward the Y2 side. The above-mentioned protrusions 513 and 514 are positioned apart from each other on the X1 and X2 sides of the fixing surface portion 512. A pair of vertical wall portions 517 are provided on the Z1 and Z2 sides of the fixing surface portion 512. A lubricating sheet 52 is fixed to the fixing surface portion 512. A fitting hole 515 is provided in the center of the fixing surface portion 512.

[0043] As shown in Fig. 6, the lubricating sheet 52 is fixed to the fixing surface portion 512, for example, via an adhesive. The lubricating sheet 52 is a composite material obtained by, for example, impregnating iron and copper-based sintered metal into molten resin and then hardening the resin. Since the rack shaft 3 is made of, for example, metal, the lubricating sheet 52 is softer than the rack shaft 3. If the lubricating sheet 52 were made of metal, both the lubricating sheet 52 and the rack shaft 3 would be made of metal, which would increase friction when the rack shaft 3 slides against the lubricating sheet 52.

[0044] As shown in FIG. 4A, the lubricating sheet 52 has a cylindrical protrusion 521 that protrudes toward the Y2 side. The protrusion 521 fits into a fitting hole 515 in the fixing surface portion 512, thereby fixing the lubricating sheet 52 to the fixing surface portion 512. As shown in FIG. 5B, the lubricating sheet 52 has two linear end faces 525 and 526 and two arcuate end faces 522 and 523 when viewed from the Y direction. The end faces 522 and 523 are spaced apart in the X direction, with the protrusion 521 (see FIG. 4A) sandwiched between them. The end face 522 is located on the X1 side, and the end face 523 is located on the X2 side. The end faces 525 and 526 are spaced apart in the Z direction, with the protrusion 521 sandwiched between them. The end face 525 is located on the Z1 side, and the end face 526 is located on the Z2 side. Note that the back surface of the lubricating sheet 52 abuts against the fixed surface portion 512 (see FIG. 4A), and therefore the shape of the lubricating sheet 52 follows the shape of the fixed surface portion 512. In FIG. 5A, the shape of the lubricating sheet 52 is arc-shaped when viewed from the X direction, but the present invention is not limited to this. That is, if the shape of the fixed surface portion 512 is, for example, V-shaped when viewed from the X direction, the shape of the lubricating sheet 52 will also be V-shaped.

[0045] As shown in FIG. 6 , the lubricating sheet 52 has a surface 524 and a back surface 524A. The surface 524 abuts or slides against the abutment portion 35 of the rack shaft 3. The back surface 524A is fixed to the fixed surface portion 512, for example, via an adhesive. An end surface 523 on the X2 side of the lubricating sheet 52 and an inner surface 514d of the convex portion 514 are spaced apart in the X direction. This allows the end surface 523, the inner surface 514d, and the bottom surface 514f to form a recessed groove 514e. The fixed surface portion 512 and the bottom surface 514f are located at the same position in the Y direction and are formed flush with each other. Furthermore, the top portion 514c of the convex portion 514 is located closer to the Y2 side than the surface 524 of the lubricating sheet 52. In other words, the height from the bottom surface 514f to the top portion 514c is lower than the height from the bottom surface 514f to the surface 524. As a result, a gap G is formed between the top portion 514c and the rack shaft 3.

[0046] Fig. 7A is a schematic enlarged view of a portion of the rack guide and rack shaft according to the first embodiment, showing an initial stage in which lubricant flows out from between the rack shaft and the lubricating sheet into the groove. Fig. 7B is a schematic enlarged view of a portion of the rack guide and rack shaft according to the first embodiment, showing an intermediate stage in which lubricant flows out from between the rack shaft and the lubricating sheet into the groove. Fig. 7C is a schematic enlarged view of a portion of the rack guide and rack shaft according to the first embodiment, showing a later stage in which lubricant flows out from between the rack shaft and the lubricating sheet into the groove.

[0047] A lubricant is disposed between the rack shaft 3 and the surface 524 to reduce sliding resistance. As shown in FIG. 7A, the rack shaft 3 slides in the X direction against the surface 524 of the lubricating sheet 52, as indicated by the arrow P. As a result, the lubricant flows into the groove 514e from between the rack shaft 3 and the surface 524, as indicated by the arrow Q1. Then, as shown in FIG. 7B, as the lubricant flows out further as indicated by the arrow Q2, the lubricant accumulates in the groove 514e, forming an oil pool OL. Then, as shown in FIG. 7C, when the liquid level in the oil pool OL rises, the lubricant in the oil pool OL flows again between the rack shaft 3 and the surface 524, as indicated by the arrow Q3.

[0048] Fig. 8A is a schematic diagram showing the force applied to the lubricating sheet from the rack shaft in the first embodiment, and Fig. 8B is a schematic diagram showing the force applied to the lubricating sheet from the rack shaft in a comparative example.

[0049] 8A, the radial width D2 in the X direction of the lubricating sheet 52 is smaller than the radial width D1 in the X direction of the main body portion 51. In contrast, in FIG. 8B, the radial width in the X direction of the lubricating sheet 52a according to the comparative example is the same as the radial width in the X direction of the main body portion 51A according to the comparative example. Therefore, as shown in FIG. 8B, the main body portion 51A according to the comparative example does not have the protrusions 513 and 514, as compared to the main body portion 51 according to the first embodiment (see FIG. 8A). Furthermore, the radial width in the X direction of the lubricating sheet 52a according to the comparative example is larger than the radial width D2 in the X direction of the lubricating sheet 52 according to the first embodiment.

[0050] 2, the tooth trace direction (tooth width direction) of the rack teeth 31 is inclined with respect to a direction perpendicular to the central axis of the rack shaft 3. Therefore, when the first pinion teeth 21 mesh with the rack teeth 31 and the rack shaft 3 reciprocates in the X direction, a force Fy shown in FIG. 8A and a force fy shown in FIG. 8B act on the lubricating sheets 52, 52a. Furthermore, as the rack shaft 3 reciprocates in the X direction, a force Fx shown in FIG. 8A and a force fx shown in FIG. 8B act on the lubricating sheets 52, 52a. Thus, in FIG. 8A relating to the first embodiment, a resultant force F of the forces Fy and Fx acts on the lubricating sheet 52, and in FIG. 8B relating to the comparative example, a resultant force f of the forces fy and fx acts on the lubricating sheet 52a.

[0051] The radial width D2 in the X direction of the lubricating sheet 52 is smaller than the radial width in the X direction of the lubricating sheet 52a according to the comparative example. Therefore, as shown in FIG. 8A, the force Fy is smaller than the force fy by a force ΔFy. In other words, as shown in FIG. 8B, the force fy is larger than the force Fy by a force ΔFy. As a result, the rack guide 5 according to the first embodiment shown in FIG. 8A is less likely to rotate around the central axis of the rack shaft 3 than the rack guide according to the comparative example shown in FIG. 8B, and noise generated when the rack teeth 31 and the first pinion teeth 21 mesh is reduced.

[0052] As described above, the steering device 80 according to the first embodiment includes the rack shaft 3, the first pinion shaft (pinion shaft) 2, and the rack guide 5 that supports the rack shaft 3. The rack guide 5 has a main body portion 51 and a lubricating sheet 52. The first surface portion 511 has a fixing surface portion 512 to which the lubricating sheet 52 is fixed, and a pair of protrusions 510 that are spaced apart on the X1 side and the X2 side relative to the fixing surface portion 512. Each of the pair of protrusions 510 extends continuously along the Z direction, faces the X-direction end faces 522, 523 of the lubricating sheet 52 over the entire Z direction, and is disposed spaced apart in the X direction from the X-direction end faces 522, 523 of the lubricating sheet 52.

[0053] As mentioned above, in Patent Document 1, the recess of the lubricating sheet is open at one end in the axial direction, so there is a possibility that the lubricant in the recess will flow out from that end, making it difficult for the lubricant to remain.

[0054] In contrast, the rack guide 5 according to this embodiment has a convex portion 510 that faces the entire Z-direction end faces 522, 523 of the lubricating sheet 52 in the X-direction. The convex portion 510 is disposed spaced apart from the end faces 522, 523 in the X-direction.

[0055] As a result, a recessed groove 514e is formed between the end faces 522, 523 of the lubricating sheet 52 and the convex portion 510. Even if a lubricant is applied between the lubricating sheet 52 and the rack shaft 3 and the lubricant flows out from between the lubricating sheet 52 and the rack shaft 3, the lubricant accumulates in the recessed groove 514e, thereby preventing the lubricant from leaking out. Furthermore, the lubricant that has accumulated in the recessed groove 514e may flow back into the gap between the lubricating sheet 52 and the rack shaft 3. As described above, according to this embodiment, it is possible to provide a steering device 80 that can further reduce the sliding resistance between the rack shaft 3 and the rack guide 5.

[0056] The Y1-side apex 514c of the convex portion 510 is located closer to the Y2 side than the Y1-side surface 524 of the lubricating sheet 52. This prevents the apex 514c of the convex portion 510 from interfering with the rack shaft 3 when the rack shaft 3 reciprocates in the X direction.

[0057] [Second embodiment] Next, a second embodiment will be described. Fig. 9A is a side view of a rack guide according to the second embodiment. Fig. 9B is a front view of the rack guide according to the second embodiment. Fig. 9C is a cross-sectional view taken along line IXC-IXC in Fig. 9B. Fig. 10 is a schematic enlarged view of a portion of the rack guide and rack shaft according to the second embodiment.

[0058] The rack guide 5A according to the second embodiment differs from the rack guide 5 according to the first embodiment in that a recess 514h is provided. The following will mainly describe this difference in detail.

[0059] As shown in FIGS. 9A to 9C, when viewed from the X1 side, the protrusion 513 extends continuously in the Z direction from the end 513a to the end 513b. The protrusion 513 is formed in an arc shape that protrudes toward the Y2 side. The protrusion 514 is also formed in an arc shape that is recessed toward the Y2 side. The protrusion 514 extends continuously in the Z direction from the end 514a to the end 514b. In this way, the protrusions 513 and 514 form a pair of protrusions 510 that protrude toward the Y1 side. The protrusions 513 and 514 face the end face of the lubricating sheet 52 in the X direction over the entire area in the Z direction.

[0060] As shown in FIG. 6 of the first embodiment, the bottom surface 514f and the fixing surface portion 512 that contacts the lubricating sheet 52 are located at the same position in the Y direction and are formed flush. In contrast, in the second embodiment, as shown in FIG. 10, the bottom surface 514g is recessed toward the Y2 side relative to the fixing surface portion 512 that contacts the lubricating sheet 52. That is, a recess 514h is provided between the fixing surface portion 512 and the protruding portion 510. The bottom surface 514g of the recess 514h is located closer to the Y2 side than the fixing surface portion 512. Therefore, the height in the Y direction from the bottom surface 514g to the top 514c of the protruding portion 510 is higher than the height in the Y direction from the bottom surface 514f to the top 514c in FIG. 6. As such, the first surface portion according to the second embodiment has a recess 514h that is recessed toward the Y2 side relative to the fixing surface portion 512 between the fixing surface portion 512 and the protruding portion 510.

[0061] As described above, in the second embodiment, the first surface portion 511 has the recessed portion 514h recessed toward the Y2 side with respect to the fixed surface portion 512 between the fixed surface portion 512 and the protruding portion 510. As a result, the recessed portion 514h is deeper than the recessed groove 514e of the first embodiment. In other words, the recessed portion 514h has a larger volume than the recessed groove 514e of the first embodiment, and therefore a larger amount of lubricant can be stored in the recessed portion 514h.

[0062] [Third embodiment] Next, a third embodiment will be described. Fig. 11 is a schematic diagram showing an enlarged view of a part of a rack guide and a rack shaft according to the third embodiment.

[0063] The rack guide 5B according to the third embodiment differs from the rack guide 5 according to the first embodiment in that it is provided with a lubricant retaining member 7. The following will mainly describe this difference in detail.

[0064] The lubricant holding member 7 shown in Fig. 11 is, for example, a sponge or brush-like member, and is capable of absorbing and holding the lubricant. The lubricant holding member 7 preferably has a small friction resistance with the rack shaft 3. As shown in Fig. 11, the lubricant holding member 7 has a rectangular cross section.

[0065] The end surface 523, the inner surface 514d, and the bottom surface 514f form a recessed groove 514e. The lubricant holding member 7 is disposed in the recessed groove 514e. A bottom surface 71 of the lubricant holding member 7 is fixed to the bottom surface 514f of the recessed groove 514e, for example, via an adhesive. A top surface 72 of the lubricant holding member 7 abuts against the rack shaft 3. As the rack shaft 3 reciprocates in the X direction, the lubricant held in the lubricant holding member 7 moves from the top surface 72 to the rack shaft 3.

[0066] In the third embodiment, the protrusions 510 act to hold the lubricant holding member 7 in the X direction. Therefore, if the lubricant holding member 7 is more firmly attached to the bottom surface 514f of the recessed groove 514e, the protrusions 510 may not be necessary.

[0067] As described above, in the third embodiment, the rack guide 5B has a main body portion 51, a lubricating sheet 52 fixed to the first surface portion 511, and a lubricant holding member 7 fixed to the first surface portion 511, abutting against the abutment portion 35, and capable of absorbing and holding lubricant.

[0068] Therefore, the lubricant held in the lubricant holding member 7 can flow into the gap between the lubricating sheet 52 and the rack shaft 3. In addition, the lubricant that flows out from between the lubricating sheet 52 and the rack shaft 3 is absorbed by the lubricant holding member 7, thereby preventing the lubricant from leaking out to the outside.

[0069] [Fourth embodiment] Next, a fourth embodiment will be described. Fig. 12 is a schematic diagram showing an enlarged view of a part of a rack guide and a rack shaft according to the fourth embodiment.

[0070] The rack guide 5C according to the fourth embodiment differs from the rack guide 5 according to the first embodiment in that it is provided with a convex portion 510A that is higher than the convex portion 510 of the rack guide 5 according to the first embodiment. The following will mainly describe this difference in detail.

[0071] As shown in FIG. 12 , the X2-side end surface 523 of the lubricating sheet 52 and the protrusion 510A are spaced apart in the X direction. As a result, the end surface 523, the protrusion 510A, and the bottom surface 514f form a recessed groove 514e. The protrusion 510A has a bottom 510Aa on the Y2 side and an apex 510Ab on the Y1 side. The Y2-side bottom 510Aa is fixed to the bottom surface 514i of the main body 51 via, for example, an adhesive. The fixing surface 512, the bottom surface 514f, and the bottom surface 514i are all flush with each other and positioned in the Y direction. Furthermore, the apex 510Ab of the protrusion 510A is positioned in the Y direction at the same position as the surface 524 of the lubricating sheet 52. Therefore, the apex 510Ab of the protrusion 510A abuts against the rack shaft 3. Here, the protrusion 510A is formed of rubber or resin. Since the rack shaft 3 is made of metal, the protrusion 510A is softer than the rack shaft 3.

[0072] As described above, in the fourth embodiment, the rack shaft 3 is made of metal, the convex portion 510A is formed of rubber or resin, and the apex 514c on the Y1 side of the convex portion 510A is positioned at the same position in the Y direction as the surface 524 on the Y1 side of the lubricating sheet 52.

[0073] Therefore, the protrusion 510A can be provided higher than the protrusion 510 of the first embodiment. Therefore, a larger amount of lubricant can be stored in the recessed groove 514e of the fourth embodiment. Furthermore, because the protrusion 510A is made of rubber or resin, even if the protrusion 510A interferes with the rack shaft 3 reciprocating in the X direction, damage to the protrusion 510A is suppressed. [Explanation of symbols]

[0074] 10 Torque sensor 2. First pinion shaft (pinion shaft) 21 1st pinion tooth 22 Housing 23 Shaft 3 rack axis 30 rack housing 30a Inside surface 31 rack teeth 32 Through hole 33 coil spring 34 Sealing member 35 Contact part 4 Second pinion shaft 5, 5A, 5B, 5C rack guide 51, 51A Main body 511 First side 512 Fixed surface part 510, 513, 514 Convex parts 510A convex part 510Aa bottom 510Ab Top 513a, 513b, 514a, 514b end 514c top 514d inner surface 514e Groove 514f Bottom 514g bottom 514h recess 514i bottom 515 Fitting hole 516, 516A flat part 517 Vertical wall section 52, 52a Lubrication sheet 521 Protrusion 522, 523 end face 524 Surface 524A back 525,526 End face 7 Lubricant retaining member 71 bottom 72 Top 80 Steering device 81 Steering wheel 82 Steering shaft 84 Universal joint 85 Intermediate shaft 86 Universal joint 87 Stub shaft (first shaft) 89 tie rod 99 ECU 100 steering gear 101 Vehicle speed sensor 102 electric motor 103 Ignition switch 104 Power supply AX Rotation Axis D1 Radial width D2 Radial width G gap OL oil puddle

Claims

1. a rack shaft extending in a first direction, having rack teeth on one side surface in a second direction intersecting the first direction, and having a contact portion on the other side in the second direction, opposite to the rack teeth; a pinion shaft located on one side of the rack teeth in the second direction, the pinion shaft having pinion teeth on its outer periphery that mesh with the rack teeth, and the pinion shaft being rotatable around the axis of the rotation shaft; a rack guide that is located on the other side of the abutment portion of the rack shaft in the second direction and abuts on the abutment portion from the other side in the second direction to support the rack shaft; Equipped with The rack guide is a main body portion having a first surface portion provided on one side in the second direction; and a lubricating sheet fixed to the first surface portion and in contact with the contact portion, the first surface portion has a fixing surface portion to which the lubricating sheet is fixed, and a pair of protrusions positioned apart from each other on one side and the other side of the fixing surface portion in the first direction and protruding to one side in the second direction, When a direction intersecting the first direction and the second direction is defined as a third direction, Each of the pair of protrusions is the lubricating sheet extends continuously along the third direction, faces the end face of the lubricating sheet in the first direction over the entire area in the third direction, and is spaced apart in the first direction from the end face of the lubricating sheet in the first direction. Steering device.

2. an apex of the protrusion on one side in the second direction is located on the other side in the second direction relative to the surface of the lubricating sheet on one side in the second direction; The steering device according to claim 1 .

3. the first surface portion has a recessed portion between the fixing surface portion and the protruding portion, the recessed portion being recessed toward the other side in the second direction relative to the fixing surface portion; 3. A steering device according to claim 1 or 2.

4. The rack shaft is made of metal, the protrusion is formed of rubber or resin, and an apex of the protrusion on one side in the second direction is disposed at the same position in the second direction with respect to the surface of the lubricating sheet on one side in the second direction. The steering device according to claim 1 .

5. a rack shaft extending in a first direction, having rack teeth on one side surface in a second direction intersecting the first direction, and having a contact portion on the other side in the second direction, opposite to the rack teeth; a pinion shaft located on one side of the rack teeth in the second direction, the pinion shaft having pinion teeth on its outer periphery that mesh with the rack teeth, and the pinion shaft being rotatable around the axis of the rotation shaft; a rack guide that is located on the other side of the abutment portion of the rack shaft in the second direction and abuts on the abutment portion from the other side in the second direction to support the rack shaft; Equipped with The rack guide is the lubricating sheet is fixed to the first surface portion and abuts against the abutment portion; and the lubricant holding member is fixed to the first surface portion and abuts against the abutment portion, and is capable of absorbing and holding lubricant. Steering device.

Images