Steering device

Abstract

To provide a steering device capable of suppressing not only deflection of a rack shaft but also generation of tooth hitting sound between a pinion tooth and a rack tooth.SOLUTION: When the axial direction of the rack shaft 3 is defined as a first direction and a direction orthogonal to both the central axis of the pinion shaft 2 and the central axis of the rack shaft 3 is defined as a second direction, the elastic support member 7 is provided only in a portion between the inner peripheral surface of the pinion housing portion 30 and the outer peripheral surface of the one side bearing 5 by disposing the deformation portions 53 only on both sides of the one side bearing 5 in the first direction. The pinion housing part 30 or the elastic support member 7 has a pair of guide parts 33 for guiding the movement of the one side bearing 5 in the first direction on both sides of the one side bearing 5 in the second direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] A steering device is incorporated in a vehicle such as an automobile, and transmits the movement of a steering wheel operated by a driver to a steering gear unit via a steering shaft, thereby applying a steering angle to the left and right steered wheels.

[0003] The steering gear unit includes a pinion shaft, a rack shaft, and a housing.

[0004] The pinion shaft is rotatably supported by a plurality of bearings inside a housing fixed to the vehicle body. The pinion shaft has pinion teeth on its outer circumferential surface and rotates in response to the rotation of the steering wheel.

[0005] The rack shaft is supported inside the housing so that it can move back and forth with its central axis oriented in the width direction of the vehicle body. The rack shaft has a plurality of rack teeth on its outer circumferential surface that mesh with the pinion teeth. Both axial ends of the rack shaft are connected to tie rods via spherical joints.

[0006] The rotational movement of the pinion shaft caused by the rotation of the steering wheel is converted into linear movement of the rack shaft, which pushes and pulls the tie rod, applying a steering angle to the left and right steered wheels according to the amount of rotation of the steering wheel. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-64562 Summary of the Invention [Problem to be solved by the invention]

[0008] A conventional technology is known in which an elastic support member is placed around the pinion shaft and a deformation portion of the elastic support member is elastically deformed to allow the pinion shaft to oscillate and displace, thereby suppressing deflection of the rack shaft due to road reaction forces.

[0009] Japanese Patent Application Laid-Open Publication No. 2010-64562 discloses a structure in which multiple elastic support members are arranged around a pinion shaft. Specifically, the structure disclosed includes a first elastic support member arranged between the outer peripheral surface of a first bearing that rotatably supports a portion of the pinion shaft further forward than the pinion teeth and the inner peripheral surface of a housing, a second elastic support member arranged between the outer peripheral surface of a portion of the pinion shaft further forward than the pinion teeth and the inner peripheral surface of a second bearing, and a third elastic support member arranged between an axially facing stepped surface provided on the pinion shaft and the axial side surface of a worm wheel that is located closer to the base end of the pinion shaft than the second bearing.

[0010] Of the first elastic support member, second elastic support member, and third elastic support member arranged around the pinion shaft, the first elastic support member and second elastic support member, which are arranged on either side of the pinion teeth in the axial direction of the pinion shaft, each have deformation portions at multiple locations circumferentially of the pinion shaft that are elastically deformable in the radial direction of the pinion shaft.

[0011] For this reason, in the conventional structure described in JP 2010-64562 A, the pinion shaft is not limited to a specific direction but can oscillate in any direction, which means that when the pinion shaft rotates, the repulsive force causes the pinion teeth and rack teeth to separate, which can easily cause teeth rattle (contact noise) when the pinion teeth and rack teeth mesh again.

[0012] An object of the present disclosure is to provide a steering device that can not only suppress deflection of the rack shaft but also suppress the occurrence of rattle noise between the pinion teeth and the rack teeth. [Means for solving the problem]

[0013] A steering device according to one aspect of the present disclosure includes a pinion shaft, a rack shaft, a housing, one-side bearings, another-side bearings, and an elastic support member.

[0014] The pinion shaft has pinion teeth on an outer circumferential surface at an axially intermediate portion thereof.

[0015] The rack shaft has rack teeth on its outer circumferential surface that mesh with the pinion teeth.

[0016] The housing has a pinion accommodating portion that rotatably accommodates one axial end of the pinion shaft and a portion including the pinion teeth, and a rack accommodating portion that accommodates the rack shaft so that it can move back and forth.

[0017] The one-side bearing supports a portion of the pinion shaft on one axial side of the pinion teeth so as to be rotatable relative to the pinion accommodating portion.

[0018] The other-side bearing supports a portion of the pinion shaft on the other axial side of the pinion teeth so as to be rotatable relative to the pinion accommodating portion.

[0019] The elastic support member is disposed around the pinion shaft and has a deformation portion that is elastically deformable in a radial direction of the pinion shaft.

[0020] When the axial direction of the rack shaft is defined as a first direction and a direction perpendicular to both the central axis of the pinion shaft and the central axis of the rack shaft is defined as a second direction, the elastic support member has the deformation portions disposed only on both sides of the one-side bearing in the first direction and is provided only in a portion between an inner circumferential surface of the pinion accommodating portion and an outer circumferential surface of the one-side bearing, The pinion accommodating portion or the elastic support member has a pair of guide portions that guide movement of the one-side bearing in the first direction, on both sides of the one-side bearing in the second direction.

[0021] In the steering device according to one aspect of the present disclosure, a cross-sectional shape of a portion of the inner circumferential surface of the pinion accommodating portion that faces the outer circumferential surface of the one-side bearing, taken along an imaginary plane perpendicular to the central axis of the pinion accommodating portion, can be non-circular. In this case, the pair of guide portions can be provided on the inner circumferential surface of the pinion accommodating portion, respectively.

[0022] In the steering device according to one aspect of the present disclosure, the cross-sectional shape of the inner circumferential surface of the elastic support member with respect to an imaginary plane perpendicular to the central axis of the pinion accommodating portion may be non-circular. In this case, the pair of guide portions may be provided on the inner circumferential surface of the elastic support member, respectively.

[0023] When the pair of guide portions are provided on the inner surface of the pinion accommodating portion, the pair of guide portions can each have a retaining groove extending in the first direction, and the elastic support member can be configured in a circular ring shape. Furthermore, both side portions of the elastic support member in the second direction can be positioned inside the retaining groove, and both side portions in the first direction can be positioned between the inner surface of the pinion accommodating portion and the outer surface of the one-side bearing, allowing them to function as the deformation portion. In this case, the elastic support member may be formed of, for example, an O-ring or a metal ring.

[0024] When the pair of guide portions are provided on the inner peripheral surfaces of the pinion accommodating portion, respectively, the elastic support member can be made up of two elastic bodies that each function as the deformation portion. In this case, the elastic body can be made of, for example, a leaf spring or a plate-shaped rubber (sheet-shaped rubber).

[0025] In the steering device according to the aspect of the present disclosure, the guide portion can be configured by a smooth surface extending in the first direction.

[0026] The steering device according to one aspect of the present disclosure may further include a torque sensor disposed around the pinion shaft and configured to detect the direction and magnitude of torque applied to the pinion shaft. In this case, the torque sensor can be disposed around a portion of the pinion shaft on the other axial side of the pinion teeth.

[0027] When the steering device according to an aspect of the present disclosure includes the torque sensor, the steering device may include a plurality of the other-side bearings. The first other-side bearing supports a portion of the pinion shaft between the torque sensor and the pinion teeth in the axial direction so as to be rotatable relative to the pinion accommodating portion, and the second other-side bearing supports a portion of the pinion shaft on the other axial side of the torque sensor in the axial direction so as to be rotatable relative to the pinion accommodating portion. [Effects of the Invention]

[0028] According to the steering device according to one aspect of the present disclosure, not only can the deflection of the rack shaft be suppressed, but also the generation of abnormal noise such as rattle noise between the pinion teeth and the rack teeth can be suppressed. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic diagram showing a steering device according to a first example of an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view corresponding to the cross section taken along line AA in FIG. [Figure 3] FIG. 3 is a schematic cross-sectional view corresponding to the cross section taken along line BB in FIG. [Figure 4] FIG. 4 is a schematic cross-sectional view corresponding to the cross section taken along line CC in FIG. [Figure 5] FIG. 5 is a schematic cross-sectional view corresponding to the cross section taken along line DD in FIG. [Figure 6] FIG. 6 is a diagram corresponding to FIG. 3 and illustrating a second example of an embodiment of the present disclosure. [Figure 7]FIG. 7 is a diagram corresponding to FIG. 4 and relating to the second example. [Figure 8] FIG. 8 is a diagram corresponding to FIG. 5 and relates to the second example. [Figure 9] FIG. 9 is a diagram corresponding to FIG. 3 and relating to a third example of an embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram corresponding to FIG. 4 and relating to the third example. [Figure 11] FIG. 11 is a diagram corresponding to FIG. 5 and relates to the third example. DETAILED DESCRIPTION OF THE INVENTION

[0030] [Example 1] A first example of an embodiment of the present disclosure will be described with reference to FIGS.

[0031] In this example, a steering device according to an aspect of the present disclosure is applied to a dual-pinion electric power steering device. However, the steering device according to an aspect of the present disclosure is not limited to dual-pinion electric power steering devices, and may be applied to steering devices of other structures.

[0032] Hereinafter, the general structure of the steering device 1 of this embodiment will be described, and then the structure of the steering gear unit 8 including the pinion shaft 2 and the rack shaft 3 will be described in detail.

[0033] In the following description of the steering device 1, the longitudinal direction refers to the longitudinal direction of the vehicle, the vertical direction refers to the up-down direction of the vehicle, and the left-right direction refers to the width direction of the vehicle. The axial direction of the rack shaft 3 is referred to as the first direction, and the direction perpendicular to both the central axis O2 of the pinion shaft 2 and the central axis O3 of the rack shaft 3 is referred to as the second direction. In this example, the first direction corresponds to the left-right direction, and the second direction corresponds to the longitudinal direction. One side with respect to the first direction refers to the left side in FIG. 1, and the other side with respect to the first direction refers to the right side in FIG. 1. One side with respect to the axial direction of the pinion shaft 2 refers to the lower side in FIGS. 2, 4, and 5, and the other side with respect to the axial direction of the pinion shaft 2 refers to the upper side in FIGS. 2, 4, and 5.

[0034] [General structure of steering device] The steering device 1 includes a pinion shaft 2, a rack shaft 3, a housing 4, one side bearing 5, other side bearings 6a, 6b, and an elastic support member 7. The pinion shaft 2, the rack shaft 3, the housing 4, the one side bearing 5, the other side bearings 6a, 6b, and the elastic support member 7 constitute a steering gear unit 8 of the steering device 1 in particular.

[0035] The steering device 1 of this example is a dual-pinion type electric power steering device, and therefore includes, in addition to the steering gear unit 8, an electric assist device 9 for applying a steering assist force to the rack shaft 3.

[0036] However, when implementing a steering device according to one aspect of the present disclosure, it is optional to provide an electric assist device. If an electric assist device is provided, the electric assist device is not limited to a structure in which auxiliary power is applied to an assist pinion shaft separate from the steering pinion shaft, as in this example, but can also apply auxiliary power to a steering shaft, a rack shaft, or a steering pinion shaft.

[0037] The steering device 1 of this example further includes a steering wheel 10, a steering shaft 11, a steering column 12, two universal joints 13a and 13b, an intermediate shaft 14, and a pair of tie rods 15.

[0038] The steering wheel 10 is attached to the rear end of a steering shaft 11. The steering shaft 11 is rotatably supported inside a steering column 12 that is supported on the vehicle body. The front end of the steering shaft 11 is connected to a steering pinion shaft 2 that constitutes a steering gear unit 8 via a rear universal joint 13a, an intermediate shaft 14, and a front universal joint 13b. Therefore, when the driver rotates the steering wheel 10, the rotation of the steering wheel 10 is transmitted to the pinion shaft 2.

[0039] The pinion shaft 2 is meshed with the rack shaft 3. Therefore, the rotational motion of the pinion shaft 2 is converted into the linear motion of the rack shaft 3. As a result, tie rods 15 connected to both ends of the rack shaft 3 via spherical joints 16 in the first direction are pushed and pulled, and a steering angle corresponding to the amount of rotation of the steering wheel 10 is applied to the left and right steered wheels 17.

[0040] The electric assist device 9 includes a torque sensor 18 , an electronic control unit 19 , an electric motor 20 , a worm reducer 21 , and an assist pinion shaft 22 .

[0041] The torque sensor 18 is disposed around the steering pinion shaft 2 and detects the direction and magnitude of torque applied to the pinion shaft 2. The torque sensor 18 is electrically connected to an electronic control unit 19. The electronic control unit 19 drives and controls the electric motor 20 based on an output signal from the torque sensor 18. The driving torque generated by the electric motor 20 is transmitted to the assist pinion shaft 22 via a worm reduction gear 21. The assist pinion shaft 22 is meshed with the rack shaft 3. Therefore, the driving torque generated by the electric motor 20 is transmitted as a steering assist force to the rack shaft 3 via the worm reduction gear 21 and the assist pinion shaft 22. As a result, the steering force required for the driver to operate the steering wheel 10 is reduced.

[0042] The steering device 1 of this example is equipped with two pinion shafts, a pinion shaft 2 and an assist pinion shaft 22, and the oscillation direction of the steering pinion shaft 2 is restricted to suppress the occurrence of gear rattle noise. However, the steering device according to one aspect of the present disclosure is not limited to the steering pinion shaft, and can also suppress the occurrence of gear rattle noise by restricting the oscillation direction of the assist pinion shaft, or by restricting the oscillation direction of both the steering pinion shaft and the assist pinion shaft.

[0043] [Steering gear unit] The steering gear unit 8 converts the rotational movement of the pinion shaft 2 that accompanies the rotation of the steering wheel 10 into the linear movement of the rack shaft 3 .

[0044] The steering gear unit 8 includes a pinion shaft 2, a rack shaft 3, a housing 4, one side bearing 5 and the other side bearings 6a and 6b, and an elastic support member 7.

[0045] <Pinion shaft> The pinion shaft 2 has pinion teeth 23 at the axially intermediate portion of the outer circumferential surface.

[0046] The pinion shaft 2 has a central axis O2, and rotates around the central axis O2 as the steering wheel 10 is rotated.

[0047] The pinion shaft 2 is rotatably supported by a one-side bearing 5 and other-side bearings 6a and 6b inside a pinion accommodating portion 30 (to be described later) that constitutes the housing 4.

[0048] In this example, one axial end of the pinion shaft 2 and a portion including the pinion teeth 23 are housed inside the pinion accommodating portion 30, and the other axial end of the pinion shaft 2 protrudes from the pinion accommodating portion 30. The other axial end of the pinion shaft 2 is connected to the intermediate shaft 14 via a universal joint 13b. A torque sensor 18 is arranged around the portion of the pinion shaft 2 that is on the other axial side of the pinion teeth 23.

[0049] The pinion shaft 2 in this example is configured by connecting a pinion body 24 that forms one half of the pinion shaft 2 in the axial direction and a shaft portion 25 that forms the other half of the pinion shaft 2 in the axial direction by a torsion bar 26.

[0050] However, when implementing a steering device according to an aspect of the present disclosure, it is optional for the pinion shaft to be made up of multiple members. In particular, if no torque sensor is disposed around the pinion shaft, the pinion shaft can be made up of a single member.

[0051] The pinion body 24 has pinion teeth 23 on its outer peripheral surface. The shaft portion 25 has a hollow cylindrical shape. The torsion bar 26 is disposed inside the shaft portion 25. One axial end of the torsion bar 26 is connected to the other axial end of the pinion body 24. The other axial end of the torsion bar 26 is connected to the other axial end of the shaft portion 25.

[0052] Torque sensor 18 is disposed around the other axial end of pinion shaft 24 and the other axial portion of shaft portion 25. Torque sensor 18 detects the direction and magnitude of torque applied to pinion shaft 2 by detecting the relative rotation direction and amount between pinion body 24 and shaft portion 25. Any method for detecting torque can be used by torque sensor 18, and for example, it is possible to employ a magnetic detection method in which a magnetic detection element faces an encoder supported and fixed to pinion body 24 and shaft portion 25, respectively, or a magnetostrictive method in which torque is detected by utilizing the magnetostrictive effect.

[0053] Rack axis The rack shaft 3 is a rod-shaped member made of metal such as carbon steel or stainless steel, etc. The rack shaft 3 has a central axis O3, and is disposed so that the central axis O3 faces in the left-right direction.

[0054] The rack shaft 3 has rack teeth 27 on a part of the circumferential direction of the outer peripheral surface of one side portion in the first direction. The rack teeth 27 mesh with pinion teeth 23 provided on the outer peripheral surface of the pinion shaft 2. The tooth thickness direction of the rack teeth 27 substantially coincides with the first direction, and the tooth height direction of the rack teeth 27 substantially coincides with the second direction.

[0055] The rack shaft 3 in this example further has assist rack teeth 29 on a part of the circumferential direction of the outer circumferential surface of the other side portion in the first direction. The assist rack teeth 29 mesh with assist pinion teeth 28 provided on the outer circumferential surface of the assist pinion shaft 22.

[0056] The rack shaft 3 is accommodated inside a rack accommodating section 31 (described later) that constitutes the housing 4 so as to be able to move back and forth in a first direction. Both ends of the rack shaft 3 in the first direction protrude from the rack accommodating section 31 and are connected to tie rods 15 via spherical joints 16.

[0057] "housing" The housing 4 is fixed to the vehicle body using fixing members such as bolts, studs, etc. The housing 4 is made by die-casting a light alloy such as an aluminum alloy, for example.

[0058] The housing 4 includes a pinion receiving portion 30 and a rack receiving portion 31 .

[0059] The rack housing portion 31 accommodates the rack shaft 3 inside thereof so that the rack shaft 3 can move back and forth. The rack housing portion 31 has a substantially cylindrical shape and is disposed substantially horizontally with its longitudinal direction directed in the width direction of the vehicle.

[0060] The pinion accommodating portion 30 rotatably accommodates therein the portion of the pinion shaft 2 including the end on one axial side and the pinion teeth 23. In this example, the pinion accommodating portion 30 rotatably accommodates therein the portion of the pinion shaft 2 excluding the end on the other axial side.

[0061] The pinion accommodating portion 30 has a one-side support portion 32 on a portion of its inner circumferential surface that faces the outer circumferential surface of the one-side bearing 5 .

[0062] In this example, the cross-sectional shape of the one-side support portion 32 in an imaginary plane perpendicular to the central axis of the pinion accommodating portion 30 (the cross-sectional shape of a portion axially deviated from a retaining groove 35, which will be described later) is not circular but non-circular. Specifically, the cross-sectional shape of the one-side support portion 32 is a broken circle or an ellipse, with both side portions broken away in the second direction (both side portions being constituted by straight portions). However, when implementing a steering device according to one aspect of the present disclosure, the cross-sectional shape of the one-side support portion is not limited to a broken circle or an ellipse, and may be, for example, a rectangle.

[0063] As shown in FIG. 3, the one-side support portion 32 has an inner dimension d1 in the first direction that is greater than an inner dimension d2 in the second direction (d1>d2).

[0064] In this example, the one-side support portion 32 has a pair of guide portions 33 on both sides of the one-side bearing 5 in the second direction, which guide the movement of the one-side bearing 5 in the first direction. However, when implementing a steering device according to one aspect of the present disclosure, the guide portions may be provided on the elastic support member instead of the one-side support portion.

[0065] The guide portions 33 are configured by smooth surfaces extending in the first direction. The pair of guide portions 33 are arranged parallel to each other.

[0066] The pair of guide portions 33 each have a retaining groove 35 extending in the first direction. The retaining groove 35 is formed in a middle portion of the guide portion 33 in the axial direction of the pinion shaft 2. The retaining groove 35 is an arch-shaped recessed groove having a center of curvature on the central axis of the pinion accommodating portion 30. The width dimension of the retaining groove 35 in the axial direction of the pinion shaft 2 is smaller than the width dimension of the one-side bearing 5 in the same direction.

[0067] The holding groove 35 holds a part of the elastic support member 7. Specifically, the holding groove 35 holds both end portions of the elastic support member 7 in the second direction.

[0068] 3, the one-side support portion 32 further has a pair of curved surface portions 34 arranged on both sides of the one-side bearing 5 in the first direction. The one-side support portion 32 is composed of a pair of guide portions 33 and a pair of curved surface portions 34.

[0069] The pair of curved surface portions 34 are partial cylindrical surfaces having a center of curvature on the central axis of the pinion accommodating portion 30. In the illustrated example, the radius of curvature of the curved surface portions 34 and the radius of curvature of the bottom surface of the retaining groove 35 are the same. Therefore, the curved surface portions 34 and the bottom surface of the retaining groove 35 are located on the same imaginary cylindrical surface.

[0070] The pinion accommodating portion 30 has other-side support portions 36a, 36b on its inner circumferential surface that faces the outer circumferential surfaces of the other-side bearings 6a, 6b. The other-side support portions 36a, 36b have a circular cross-sectional shape with respect to an imaginary plane perpendicular to the central axis of the pinion accommodating portion 30. Therefore, the other-side support portions 36a, 36b are configured as cylindrical surfaces.

[0071] The pinion accommodating portion 30 of this example is composed of a pinion accommodating portion main body 37, a lower cover 38, and an upper cover 39. However, when implementing a steering device according to one aspect of the present disclosure, it is optional for the pinion accommodating portion to be composed of multiple members.

[0072] The pinion accommodating portion main body 37 has a stepped cylindrical shape and is connected to a portion of the circumference of one side (the left side in FIG. 1) of the rack accommodating portion 31 in the first direction. In this example, the pinion accommodating portion main body 37 and the rack accommodating portion 31 are integrally configured.

[0073] The central axis of the pinion accommodating portion main body 37 coincides with the central axis of the pinion accommodating portion 30 and is disposed at a skewed position with respect to the central axis of the rack accommodating portion 31. When viewed from the front-to-rear direction, the central axis of the pinion accommodating portion main body 37 is not disposed in a direction perpendicular to the central axis of the rack accommodating portion 31, but is inclined with respect to the perpendicular direction. The internal space of the pinion accommodating portion main body 37 communicates with the internal space of the rack accommodating portion 31.

[0074] The pinion accommodating portion main body 37 has a one-side support portion 32 at one axial end of its inner circumferential surface, and has a other-side support portion 36a at an axial intermediate portion of its inner circumferential surface.

[0075] The lower cover 38 has a cylindrical shape with a bottom, and closes an opening on one axial side of the pinion accommodating portion main body 37 .

[0076] The upper lid 39 is fixed to an opening on the other axial side of the pinion accommodating portion main body 37. The upper lid 39 has an insertion hole 40 through which the other axial side portion of the pinion shaft 2 is inserted. In this example, the upper lid 39 has an other-side support portion 36b on its inner peripheral surface.

[0077] The housing 4 of this example further includes a guide receiving portion 41 .

[0078] The guide accommodating portion 41 accommodates therein a pressing mechanism 43 including a rack guide 42 that presses the rack shaft 3 toward the pinion shaft 2. The guide accommodating portion 41 has a cylindrical shape and is connected to a portion of the rack accommodating portion 31 that is diametrically opposite to the pinion accommodating portion 30. The central axis of the guide accommodating portion 41 faces in the second direction. The internal space of the guide accommodating portion 41 communicates with the internal space of the rack accommodating portion 31.

[0079] The pressing mechanism 43 includes a rack guide 42 and a pressing member 44. The pressing member 44 is disposed in an elastically compressed state between the rack guide 42 and a cap 45 that closes the opening of the guide housing portion 41. The rack guide 42 uses the elastic force of the pressing member 44 to elastically press the rack shaft 3 toward the pinion shaft 2. This reduces backlash at the meshing portion between the pinion teeth 23 and the rack teeth 27. Furthermore, the meshing state between the pinion teeth 23 and the rack teeth 27 is properly maintained regardless of a force acting on the rack shaft 3 in a direction away from the pinion shaft 2 due to power transmission at the meshing portion. In this example, the pressing mechanism 43 has a sliding structure, but it may also have a rolling structure.

[0080] The housing 4 of this example further has an assist pinion accommodating portion 46 and a gear housing portion 47 on the other side (right side in FIG. 1) of the rack accommodating portion 31 in the first direction. The assist pinion accommodating portion 46 rotatably accommodates the assist pinion shaft 22 therein. The gear housing portion 47 accommodates the worm reducer 21 therein.

[0081] Although not shown in the figures, the housing 4 in this example further has an assist guide accommodating section in the part of the rack accommodating section 31 that is diametrically opposite to the assist pinion accommodating section 46, which accommodates a pressing mechanism that presses the rack shaft 3 toward the assist pinion shaft 22.

[0082] One-side bearing The one-side bearing 5 supports a portion of the pinion shaft 2 on one axial side of the pinion teeth 23 so as to be rotatable relative to the pinion accommodating portion 30 .

[0083] The steering device 1 of this example has only one one-side bearing 5. Therefore, the pinion shaft 2 is rotatably supported in the pinion accommodating portion 30 by the one one-side bearing 5 at a portion on one axial side of the pinion teeth 23.

[0084] In this example, the one-side bearing 5 is configured as a single-row rolling bearing. However, when implementing a steering device according to one aspect of the present disclosure, the one-side bearing may be configured as a plain bearing or a double-row rolling bearing.

[0085] In this example, the one-side bearing 5 is configured as a ball bearing. However, when implementing a steering device according to one aspect of the present disclosure, the one-side bearing may also be configured as a roller bearing or a needle bearing.

[0086] The one-side bearing 5 includes an inner ring 48 , an outer ring 49 , and a plurality of rolling elements 50 arranged between the outer peripheral surface of the inner ring 48 and the inner peripheral surface of the outer ring 49 .

[0087] The inner ring 48 is tightly fitted onto the pinion shaft 2 at a portion adjacent to one axial side of the pinion teeth 23. The inner ring 48 is prevented from coming off by a nut 51 fixed to the end of the pinion shaft 2 at one axial side.

[0088] The outer ring 49 is disposed in the pinion accommodating portion 30 on the radially inner side of the one-side support portion 32 .

[0089] The outer diameter D5 of the outer ring 49 is smaller than the inner dimension d1 in the first direction among the inner dimensions of the one-side support portion 32 and is slightly smaller than the inner dimension d2 in the second direction (D5 < d2 < d1). In other words, the outer diameter D5 of the outer ring 49 is smaller than the distance between the bottoms of the pair of curved surface portions 34 (= inner dimension d1) and is slightly smaller than the distance between the pair of guide portions 33 (= inner dimension d2). Specifically, the outer diameter D5 of the outer ring 49 is smaller than the inner dimension d1 in the first direction by such an extent that the one-side bearing 5 (outer ring 49) can move in the first direction inside the one-side support portion 32. Also, the outer diameter D5 of the outer ring 49 is smaller than the inner dimension d2 in the second direction by such an extent that it allows the one-side bearing 5 (outer ring 49) to move in the first direction inside the one-side support portion 32 and that the one-side bearing 5 (outer ring 49) does not rattle in the second direction inside the one-side support portion 32.

[0090] Therefore, in the neutral state of the pinion shaft 2 where the central axis O2 of the pinion shaft 2 and the central axis of the pinion housing portion 30 coincide, there is a partial circular arc-shaped space 52 between the curved surface portion 34 of the one-side support portion 32 and the outer peripheral surface of the one-side bearing 5, but there is almost no gap between the portion of the guide portion 33 of the one-side support portion 32 that is out of the holding groove 35 and the top of the outer peripheral surface of the one-side bearing 5.

[0091] 《Other-side bearing》 The other-side bearings 6a and 6b rotatably support the portion of the pinion shaft 2 on the other axial side of the pinion teeth 23 with respect to the pinion housing portion 30.

[0092] The steering device 1 of this example includes a plurality of the other-side bearings 6a and 6b. Specifically, the steering device 1 includes two of the other-side bearings 6a and 6b. Therefore, the portion of the pinion shaft 2 on the other axial side of the pinion teeth 23 is rotatably supported by the two other-side bearings 6a and 6b with respect to the pinion housing portion 30.

[0093] However, when implementing a steering device according to an aspect of the present disclosure, the number of other-side bearings is not limited to two, and it is also possible to provide only one, or three or more.

[0094] The two other-side bearings 6a, 6b are arranged apart in the axial direction of the pinion shaft 2. Of the two other-side bearings 6a, 6b, the first other-side bearing 6a, which is arranged on one side in the axial direction of the pinion shaft 2, rotatably supports a portion of the pinion shaft 2 between the torque sensor 18 and the pinion teeth 23 in the axial direction relative to the pinion accommodating portion 30. In this example, the first other-side bearing 6a rotatably supports the end of the pinion body 24 on the other axial side relative to the other axial side portion of the pinion accommodating portion main body 37.

[0095] The first other-side bearing 6a is arranged in the pinion accommodating portion 30, radially inward of the other-side support portion 36a.

[0096] The first other-side bearing 6a is fitted onto the pinion shaft 2 in a portion between the torque sensor 18 and the pinion teeth 23 in the axial direction, and is directly fitted into the other-side support portion 36a of the pinion accommodating portion 30. Specifically, the first other-side bearing 6a is fitted onto the other axial end of the pinion body 24 with an interference fit, and is fitted into the other-side support portion 36a with a clearance fit.

[0097] Of the two other-side bearings 6a, 6b, the second other-side bearing 6b, which is arranged on the other side in the axial direction of the pinion shaft 2, rotatably supports a portion of the pinion shaft 2 that is on the other axial side of the torque sensor 18 relative to the pinion accommodating portion 30. In this example, the second other-side bearing 6b rotatably supports an intermediate portion of the shaft portion 25 relative to the upper cover 39.

[0098] The second other-side bearing 6b is arranged in the pinion accommodating portion 30, radially inward of the other-side support portion 36b.

[0099] The second other-side bearing 6b is fitted onto the pinion shaft 2 at a portion on the other side of the torque sensor 18 in the axial direction, and is directly fitted into the other-side support portion 36b of the pinion accommodating portion 30. Specifically, the second other-side bearing 6b is fitted onto the axially intermediate portion of the shaft portion 25 with a clearance fit, and is fitted into the other-side support portion 36b with an interference fit.

[0100] In this example, the other side bearings 6a and 6b are both formed by rolling bearings having internal clearances, and the other side bearings 6a and 6b are also formed by ball bearings.

[0101] <Elastic support member> The elastic support member 7 is disposed around the pinion shaft 2 and has a deformation portion 53 that is elastically deformable in the radial direction of the pinion shaft 2.

[0102] The elastic support member 7 is made of an elastic material such as rubber or metal, and has an overall annular shape. In this example, the elastic support member 7 is made of a rubber O-ring.

[0103] When implementing a steering device according to one embodiment of the present disclosure, the material of the elastic support member can be selected arbitrarily and is not limited to an elastic material, and may be made of metal, composite material, etc. In the illustrated example, the cross-sectional shape of the elastic support member 7 is rectangular, but the cross-sectional shape of the elastic support member is arbitrary, and other shapes such as a circle or an ellipse can be adopted.

[0104] In this example, the elastic support member 7 is composed of one member. However, when implementing a steering device according to one aspect of the present disclosure, the elastic support member may be composed of multiple members. Furthermore, when the elastic support member is composed of multiple members, the multiple members do not need to be connected to each other.

[0105] The elastic support member 7 has deformable portions 53 disposed only on both sides of the one-side bearing 5 in the first direction, and is provided only in the portion between the inner peripheral surface of the pinion accommodating portion 30 and the outer peripheral surface of the one-side bearing 5.

[0106] In other words, the elastic support member 7 is not provided in the portion between the inner peripheral surface of the one-side bearing 5 and the outer peripheral surface of the pinion shaft 2, the portion between the inner peripheral surface of the pinion accommodating portion 30 and the outer peripheral surfaces of the other-side bearings 6a, 6b, and the portion between the inner peripheral surfaces of the other-side bearings 6a, 6b and the outer peripheral surface of the pinion shaft 2. In addition, the deforming portion 53 is not provided on either side of the one-side bearing 5 in the second direction.

[0107] In a free state, the elastic support member 7 has an inner diameter slightly larger than the outer diameter D5 of the one-side bearing 5, and an outer radius approximately the same as the radius of curvature of the curved surface portion 34 that constitutes the one-side support portion 32.

[0108] The elastic support member 7 is disposed in a portion between the one-side support portion 32 of the pinion accommodating portion 30 and the outer peripheral surface of the outer ring 49 of the one-side bearing 5 .

[0109] The elastic support member 7 has both side portions in the second direction disposed inside the retaining groove 35. Therefore, the both side portions of the elastic support member 7 in the second direction are not pressed by the outer peripheral surface of the pinion shaft 2 and are not elastically deformed in the radial direction of the pinion shaft 2, and do not function as deforming portions.

[0110] In contrast, of the elastic support member 7, both side portions in the first direction are arranged in the space 52 between the curved surface portion 34 and the outer peripheral surface of the one-side bearing 5. Therefore, of the elastic support member 7, both side portions in the first direction are pressed by the outer peripheral surface of the outer ring 49 of the one-side bearing 5 as the pinion shaft 2 swings, and are elastically deformable in the radial direction of the pinion shaft 2, and these portions function as deforming portions 53.

[0111] Therefore, the pinion shaft 2 can swing in the first direction by elastically deforming the deformation portion 53 of the elastic support member 7. That is, the pinion shaft 2 can move its one axial end portion toward one side in the first direction from the neutral position by elastically deforming the deformation portion 53 on one side of the one-side bearing 5 in the first direction, and can move its one axial end portion toward the other side in the first direction from the neutral position by elastically deforming the deformation portion 53 on the other side of the one-side bearing 5 in the first direction.

[0112] Furthermore, in the elastic support member 7 of this example, both side portions in the second direction are respectively arranged inside the retaining grooves 35 of the guide parts 33, so that the movement of the one-side bearing 5 in the first direction is guided by the portions of the pair of guide parts 33 that are out of the retaining grooves 35. In other words, the pair of guide parts 33 restrict the movement direction of the one-side bearing 5 and the end part on one axial side of the pinion shaft 2 fitted in the one-side bearing 5 to only the first direction.

[0113] As a result, the pinion shaft 2 can swing only in the first direction. Specifically, the pinion shaft 2 has a portion on the other axial side of the pinion teeth 23 that is located at the swing center O. S In this example, the pinion shaft 2 oscillates around the center of the first other-side bearing 6a, which is disposed at a position close to the pinion teeth 23 in the axial direction of the pinion shaft 2, of the two other-side bearings 6a and 6b. S It oscillates as.

[0114] The swing angle of pinion shaft 2 is determined by the internal clearance of other-side bearings 6a and 6b, the radial dimension of space 52, and Young's modulus of deformation portion 53. In this example, pinion shaft 2 can swing from the neutral state in the first direction by about ±3 degrees, preferably about ±1 degree.

[0115] According to the steering device 1 of this embodiment, not only can the deflection of the rack shaft 3 be suppressed, but also the occurrence of teeth rattle noise (contact noise) between the pinion teeth 23 and the rack teeth 27 can be suppressed.

[0116] In the steering device 1 of this example, the elastic support member 7 has deformation portions 53 that are elastically deformable in the radial direction of the pinion shaft 2 arranged only on both sides of the one-side bearing 5 in the first direction, and arranged only in the portion between the inner circumferential surface of the pinion accommodating portion 30 and the outer circumferential surface of the one-side bearing 5. In addition, the one-side support portion 32 provided on the inner circumferential surface of the pinion accommodating portion 30 has a pair of guide portions 33 on both sides of the one-side bearing 5 in the second direction that guide movement of the one-side bearing 5 in the first direction. Therefore, in the steering device 1 of this example, the pinion shaft 2 can swing only in the first direction.

[0117] Therefore, even when a large force acting in the first direction is applied to the rack shaft 3 due to a road surface reaction force or the like, the pinion shaft 2 swings in the first direction, thereby suppressing deflection of the rack shaft 3. This also suppresses damage to the rack teeth 27. Furthermore, because the pinion shaft 2 swings only in the first direction, the pinion teeth 23 and the rack teeth 27 do not separate even when a separating force is applied, and meshing between the pinion teeth 23 and the rack teeth 27 is maintained, thereby suppressing the generation of meshing noise that occurs when the pinion teeth 23 and the rack teeth 27 that have once disengaged mesh again. Furthermore, because the pinion teeth 23 and the rack teeth 27 do not separate even when a separating force is applied, a decrease in torque transmission efficiency due to a decrease in the meshing ratio is suppressed.

[0118] In this example, the pair of guide portions 33 provided on the inner peripheral surface of the pinion accommodating portion 30 each have the retaining groove 35, so even if an annular member such as an O-ring is used as the elastic support member 7, only the portions on both sides in the first direction can function as the deformation portion 53. Therefore, a general-purpose member with the same properties over the entire circumference can be used as the elastic support member 7, which makes it possible to suppress an increase in the cost of the steering device 1.

[0119] In this example, the elastic support member 7 is disposed only in a portion of the inner circumferential surface of the pinion accommodating portion 30 between the one-side support portion 32 and the outer circumferential surface of the one-side bearing 5. The elastic support member 7 is not disposed in a portion between the outer circumferential surfaces of the two other-side bearings 6 a, 6 b disposed on both sides of the torque sensor 18 in the axial direction of the pinion shaft 2 and the inner circumferential surface of the pinion accommodating portion 30, or in a portion between the inner circumferential surfaces of the two other-side bearings 6 a, 6 b and the outer circumferential surface of the pinion shaft 2. This makes it possible to sufficiently reduce the displacement (swing angle) of the portion of the pinion shaft 2 around which the torque sensor 18 is disposed. This therefore ensures sufficient detection accuracy of the torque sensor 18.

[0120] [Example 2] A second example of the embodiment of the present disclosure will be described with reference to FIGS.

[0121] In this example, only the structures of the one side support portion 32a of the pinion accommodating portion 30 that constitutes the housing 4 and the elastic support member 7a are changed from the structures of the one side support portion 32 and the elastic support member 7 of the first example.

[0122] The one-side support portion 32a of this example does not have a holding groove in the guide portion 33a, as shown in Fig. 8. Therefore, the guide portion 33a is entirely made up of a flat surface.

[0123] In this example, the one-side support portion 32a is also composed of a pair of guide portions 33a and a pair of curved portions 34, and the cross-sectional shape with respect to an imaginary plane perpendicular to the central axis of the pinion accommodating portion 30 is a missing circle or an ellipse with both sides missing in the second direction.

[0124] Unlike the elastic support member 7 of the first example, the elastic support member 7a of this example is composed of two members. That is, the elastic support member 7a is composed of two elastic bodies 54, each of which functions as a deformation portion 53a. Specifically, the elastic bodies 54 are composed of leaf springs. When the pinion shaft 2 is in a neutral state, the elastic bodies 54 are elastically sandwiched between the curved surface portion 34 constituting the one-side support portion 32a and the outer circumferential surface of the one-side bearing 5.

[0125] When implementing a steering device according to one aspect of the present disclosure, the material of the elastic body can be selected arbitrarily and is not limited to metal, but may be rubber, a composite material, or the like. The cross-sectional shape of the elastic body can also be selected arbitrarily. In this example, the elastic body 54 arranged on one side of the one-side bearing 5 in the first direction and the elastic body 54 arranged on the other side of the one-side bearing 5 in the first direction are common components, but different components with different Young's moduli, for example, can also be used.

[0126] In this example, elastic bodies 54 functioning as deformation portions 53a are arranged on both sides (spaces 52) of one-side bearing 5 in the first direction, and a pair of guide portions 33a are arranged on both sides of one-side bearing 5 in the second direction. Therefore, by elastically deforming deformation portions 53a, pinion shaft 2 can oscillate only in the first direction.

[0127] Therefore, in the steering device 1 of this example, not only can deflection of the rack shaft 3 be suppressed, but also the occurrence of rattle noise between the pinion teeth 23 and the rack teeth 27 can be suppressed. Furthermore, in this example, there is no need to form a retaining groove in the guide portion 33a, which reduces the processing costs of the housing 4. Also, the elastic support member 7a can be formed from the elastic body 54 made of a leaf spring, which also reduces costs.

[0128] Other configurations and effects of the second example are the same as those of the first example.

[0129] [Example 3] A third example of the embodiment of the present disclosure will be described with reference to FIGS.

[0130] In this example, only the structure of one side support portion 32b of the pinion accommodating portion 30 that constitutes the housing 4 and the elastic support member 7b have been changed from the structure of the one side support portion 32 and the elastic support member 7 of the first example and the structure of the one side support portion 32a and the elastic support member 7a of the second example.

[0131] 9, the one-side support portion 32b in this example has a circular cross-sectional shape in an imaginary plane perpendicular to the central axis of the pinion accommodating portion 30, and does not have a pair of guide portions on both sides of the one-side bearing 5 in the second direction. The one-side support portion 32b is formed of a cylindrical surface.

[0132] In this example, the elastic support member 7b has a pair of guide portions 33b on both sides of the one-side bearing 5 in the second direction, which guide the movement of the one-side bearing 5 in the first direction.

[0133] The elastic support member 7b in this example has an overall annular shape and has deformable portions 53b made of an elastic material such as rubber on both sides of the one-side bearing 5 in the first direction, and has non-deformable portions 55 on both sides of the one-side bearing 5 in the second direction.

[0134] Non-deformable portion 55 is made of, for example, synthetic resin or metal, and does not substantially elastically deform in the radial direction of pinion shaft 2 even when pressed by pinion shaft 2. Non-deformable portion 55 has guide portion 33b on the surface facing one-side bearing 5. Guide portion 33b is configured with a smooth surface extending in the first direction. The pair of guide portions 33b are arranged parallel to each other.

[0135] The deformed portion 53b and the non-deformed portion 55 are connected by, for example, vulcanization adhesion.

[0136] In this example, a pair of deforming portions 53b of the elastic support member 7b are arranged on both sides of the one-side bearing 5 in the first direction, and a pair of guide portions 33b provided on the non-deforming portion 55 of the elastic support member 7b are arranged on both sides of the one-side bearing 5 in the second direction. Therefore, the pinion shaft 2 can oscillate only in the first direction by elastically deforming the deforming portions 53b of the elastic support member 7b.

[0137] Therefore, in the steering device 1 of this example, it is possible to suppress not only the deflection of the rack shaft 3 but also the occurrence of teeth rattle noise between the pinion teeth 23 and the rack teeth 27. Furthermore, in this example, the one-side support portion 32b can be configured with a cylindrical surface, which reduces the processing cost of the housing 4.

[0138] The other configurations and effects of the third example are the same as those of the first example. [Explanation of symbols]

[0139] 1 Steering device 2 pinion shaft 3 rack axis 4. Housing 5 One side bearing 6a, 6b Other side bearing 7, 7a, 7b Elastic support members 8 Steering gear unit 9 Electric assist device 10. Steering wheel 11 Steering shaft 12 Steering column 13a, 13b Universal joint 14 Intermediate shaft 15 tie rod 16 Spherical joint 17 Steering Wheel 18 Torque sensor 19 Electronic Control Unit 20 Electric motor 21 Worm reducer 22 Assist pinion shaft 23 pinion teeth 24 Pinion body 25 shaft section 26 Torsion bar 27 rack teeth 28 assist pinion teeth 29 Assist rack teeth 30 Pinion housing 31 Rack storage area 32, 32a, 32b One side support part 33, 33a, 33b Guide part 34 Curved part 35 Retaining groove 36a, 36b Other side support part 37 Pinion housing body 38 Lower lid 39 Top lid 40 Insertion hole 41 Guide housing 42 Rack guide 43 Pressing mechanism 44 Pressing member 45 Cap 46 Assist pinion housing 47 Gear housing part 48 Inner Circle 49 Outer Ring 50 rolling elements 51 Nut 52 Space 53, 53a, 53b Deformed part 54 Elastic Body 55 Non-deformed part

Claims

1. a pinion shaft having pinion teeth at an axially intermediate portion of an outer peripheral surface thereof; a rack shaft having rack teeth on its outer circumferential surface that mesh with the pinion teeth; a housing including a pinion accommodating portion that rotatably accommodates an end portion of the pinion shaft on one axial side and a portion including the pinion teeth, and a rack accommodating portion that accommodates the rack shaft so that the rack shaft can move back and forth; a one-side bearing that rotatably supports a portion of the pinion shaft on one axial side of the pinion teeth relative to the pinion accommodating portion, and an other-side bearing that rotatably supports a portion of the pinion shaft on the other axial side of the pinion teeth relative to the pinion accommodating portion; an elastic support member disposed around the pinion shaft and having a deformation portion that is elastically deformable in a radial direction of the pinion shaft; Equipped with When the axial direction of the rack shaft is defined as a first direction and a direction perpendicular to both the central axis of the pinion shaft and the central axis of the rack shaft is defined as a second direction, the elastic support member has the deformation portions disposed only on both sides of the one-side bearing in the first direction and is provided only in a portion between an inner circumferential surface of the pinion accommodating portion and an outer circumferential surface of the one-side bearing, the pinion accommodating portion or the elastic support member has a pair of guide portions on both sides of the one-side bearing in the second direction, the guide portions guiding movement of the one-side bearing in the first direction; Steering device.

2. a portion of an inner peripheral surface of the pinion accommodating portion that faces an outer peripheral surface of the one-side bearing has a non-circular cross-sectional shape with respect to an imaginary plane perpendicular to a central axis of the pinion accommodating portion, The pair of guide portions are provided on the inner peripheral surface of the pinion accommodating portion, The steering device according to claim 1 .

3. The pair of guide portions each have a holding groove extending in the first direction, the elastic support member has an annular shape, both side portions in the second direction are disposed inside the retaining groove, and both side portions in the first direction are disposed between an inner peripheral surface of the pinion accommodating portion and an outer peripheral surface of the one-side bearing, and function as the deformation portion. The steering device according to claim 2 .

4. 3. The steering device according to claim 2, wherein the elastic support member is made up of two elastic bodies each functioning as the deformation portion.

5. The steering device according to claim 1 , wherein the guide portion is configured by a smooth surface extending in the first direction.

6. a torque sensor disposed around the pinion shaft and configured to detect the direction and magnitude of torque applied to the pinion shaft; the torque sensor is disposed around a portion of the pinion shaft on the other axial side of the pinion teeth, The steering device according to claim 1 .

7. a plurality of the other-side bearings are provided, the first other-side bearing supports a portion of the pinion shaft between the torque sensor and the pinion teeth in the axial direction so as to be rotatable relative to the pinion accommodating portion, the second other-side bearing supports a portion of the pinion shaft that is on the other axial side of the torque sensor in the axial direction so as to be rotatable relative to the pinion accommodating portion; The steering device according to claim 6.

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