Steering device

Abstract

This steering device comprises: a support cylinder (17) that supports a steering shaft (2); and a housing (18) having a cylindrical portion (41) in which a reduction gear (20) is housed. A bearing support member (50) is fitted to the inner circumferential surface of the cylindrical portion (41). A bearing (71) is disposed between the outer circumferential surface of the steering shaft (2) and the inner circumferential surface of the bearing support member (50). The bearing support member (50) has an inner circumferential wall (51) that is fitted to the outer circumferential surface of the bearing (71), an outer circumferential wall (52) that is fitted to the inner circumferential surface of the cylindrical portion (41), and a coupling wall (53) that couples the inner circumferential wall (51) and the outer circumferential wall (52) in a radial direction. The inner circumferential wall (51) extends from the coupling wall (53) in the same direction as a mounting direction (DW), and the outer circumferential wall (52) extends in the direction opposite to the mounting direction (DW).

Description

[Technical Field]

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

[0002] Conventionally, there are electric power steering devices that use a motor to assist steering. For example, the steering device disclosed in Patent Document 1 has a motor and a bearing unit. A steering shaft passes through the bearing unit in the axial direction. The bearing unit has a housing. The housing has a casing and a casing cover. The casing has an opening that opens in the axial direction. The casing cover is attached to the casing so as to close the opening of the casing.

[0003] The housing accommodates a helical gear and a buffer disc. The helical gear is connected to the steering shaft so as to be rotatable together. The helical gear is driven by a motor. The helical gear is supported axially by both a first bearing and a second bearing. The first bearing is provided on the buffer disc. The second bearing is provided on an end wall of the casing. The end wall is the wall opposite the opening. The steering shaft is rotatably supported relative to the casing via the first bearing and the second bearing.

[0004] The buffer disc is located axially between the helical gear and the casing cover. The buffer disc is attached to the outer peripheral surface of the steering shaft via a first bearing. The outer peripheral surface of the buffer disc abuts against the inner peripheral surface of the casing. A portion of the casing cover is supported on the side of the buffer disc via a spring member. The spring member applies an axial elastic force to the buffer disc toward the helical gear. The elastic force of the spring member prevents the buffer disc from moving away from the helical gear.

[0005] The buffer disc functions to buffer shocks acting in the radial and axial directions of the steering shaft. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2018-520926 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, customer demands for steering devices have become increasingly diverse based on vehicle specifications, etc. In order to meet these demands, extensive research and development has been conducted on the configuration of steering devices. Steering devices with novel configurations are required. [Means for solving the problem]

[0008] A steering device according to one aspect of the present disclosure includes a cylindrical support tube having a flange and rotatably supporting a steering shaft, a reducer configured to apply torque to the steering shaft, a housing having a cylindrical portion for accommodating the reducer and coaxially connected to the flange, a bearing support member fitted to the inner peripheral surface of the cylindrical portion from an installation direction along the axial direction, the bearing support member through which the steering shaft passes, and a bearing interposed between the outer peripheral surface of the steering shaft and the inner peripheral surface of the bearing support member. The bearing support member has an inner peripheral wall fitted to the outer peripheral surface of the bearing, an outer peripheral wall fitted to the inner peripheral surface of the cylindrical portion, and a connecting wall radially connecting the inner peripheral wall and the outer peripheral wall. The inner peripheral wall has a base end connected to the connecting wall and extends from the connecting wall in the same direction as the installation direction. The outer peripheral wall has a base end connected to the connecting wall and extends from the connecting wall in a direction opposite to the installation direction. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a configuration of a steering device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view of the steering column of FIG. 1. [Figure 3] 3 is a cross-sectional view of a connecting portion between the housing and the lower tube in FIG. 2. [Figure 4] FIG. 4 is a perspective view of the bearing support member of FIG. 3 as seen obliquely from above. [Figure 5] 4 is a perspective view of the bearing support member of FIG. 3, seen obliquely from below. FIG. [Figure 6] FIG. 4 is a half cross-sectional view of the bearing support member of FIG. 3. [Figure 7] FIG. 4 is a half cross-sectional view of the bearing support member of FIG. 3. [Figure 8] FIG. 10 is a cross-sectional view of a housing according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment A first embodiment of a steering device will be described. As shown in FIG. 1, the steering device 1 has a steering shaft 2, an intermediate shaft 3, a pinion shaft 4, and a rack shaft 5. A steering wheel 6 is connected to a first end of the steering shaft 2. A first end of the intermediate shaft 3 is connected to a second end of the steering shaft 2 via a universal joint 7. A first end of the pinion shaft 4 is connected to the second end of the intermediate shaft 3 via a universal joint 8. A pinion 4a is provided at the second end of the pinion shaft 4. The pinion 4a meshes with a rack 5a provided on a rack shaft 5. The rack shaft 5 is supported inside a housing 10 fixed to a frame 9 of the vehicle body. The rack shaft 5 is movable left or right relative to the traveling direction of the vehicle. Both ends of the rack shaft 5 are connected to left and right steered wheels (not shown) via tie rods (not shown).

[0011] The steering shaft 2 has an outer shaft 11 and an inner shaft 12. The outer shaft 11 and the inner shaft 12 are connected to each other by, for example, a spline connection. The outer shaft 11 and the inner shaft 12 are rotatable together and are movable relative to each other along their axial directions. The steering shaft 2 is disposed obliquely with respect to the longitudinal direction of the vehicle, with the steering wheel 6 facing upward.

[0012] The steering device 1 has a steering column 15. A steering shaft 2 is inserted through the steering column 15. The steering shaft 2 is rotatably supported on the steering column 15 via a bearing (not shown). The steering column 15 is attached to two frames 13, 14 provided on the vehicle body. One frame 13 is located rearward of the other frame 14 in the front-to-rear direction of the vehicle.

[0013] The steering column 15 has an upper tube 16, a lower tube 17, and a housing 18. The upper tube 16 is cylindrical. The lower tube 17 is cylindrical and has a flange 31. The upper tube 16 and the lower tube 17 are fitted together. As an example, the upper tube 16 is inserted into a first end of the lower tube 17. The first end is the end opposite to the second end where the flange 31 is provided. The upper tube 16 and the lower tube 17 are movable relative to each other in the axial direction of the steering shaft 2. The lower tube 17 has a column bracket 17A. The lower tube 17 is attached to the vehicle frame 13 via the column bracket 17A.

[0014] The upper tube 16 and the lower tube 17 are made of, for example, a magnetic material. The magnetic material includes a magnetic metal such as iron. The upper tube 16 and the lower tube 17 form a support tube that rotatably supports the steering shaft 2.

[0015] The housing 18 is connected to a second end of the lower tube 17. The housing 18 has two support portions 18A (only one is shown in FIG. 1 ) and a support shaft 18B. The two support portions 18A are provided on the side of the housing 18 opposite the lower tube 17. The two support portions 18A face each other in the width direction of the vehicle body. The support shaft 18B extends between the two support portions 18A. The support shaft 18B is rotatably connected to a bracket 24 fixed to the frame 14 of the vehicle body.

[0016] A steering assist motor 19 is provided outside the housing 18. A reducer 20 is accommodated inside the housing 18. The reducer 20 reduces the rotation speed of the motor 19 and transmits the reduced rotation to the inner shaft 12. The reducer 20 is a worm reducer having a worm 21 and a worm wheel 22. The worm 21 is connected to an output shaft (not shown) of the motor 19 so as to be rotatable together with it. The axis of the worm 21 and the axis of the output shaft of the motor 19 are located on the same straight line. The worm wheel 22 is engaged with the worm 21. The worm wheel 22 is provided so as to be rotatable together with the inner shaft 12. The axis of the worm wheel 22 and the axis of the inner shaft 12 are located on the same straight line.

[0017] The steering device 1 has a locking mechanism (not shown). The locking mechanism selectively locks and unlocks the swinging of the steering column 15 around the support shaft 18B and the extension and retraction of the steering column 15 through the operation of a lever (not shown). By operating the lever to unlock, the steering column 15 can swing around the support shaft 18B relative to the column bracket 17A. After operating the lever to unlock, the vertical position of the steering wheel 6 can be adjusted by moving the steering wheel 6 up or down. Furthermore, by operating the lever to unlock, the upper tube 16 can move in the axial direction of the steering shaft 2 relative to the lower tube 17. After operating the lever to unlock, the steering wheel 6 can be moved in the axial direction of the steering shaft 2, thereby adjusting the axial position of the steering wheel 6.

[0018] Next, the configuration of the lower tube 17 will be described in detail. As shown in FIG. 2, the lower tube 17 has a flange 31. The flange 31 is provided at a second end of the lower tube 17. The second end of the lower tube 17 is the end opposite the first end into which the upper tube 16 is inserted. The flange 31 is an annular flat plate. The flange 31 has two mounting portions 31A. The two mounting portions 31A are provided on the outer peripheral surface of the flange 31. The two mounting portions 31A protrude radially outward from the outer peripheral surface of the flange 31. The two mounting portions 31A are located on opposite sides of the flange 31 in the radial direction. As shown in FIG. 3, each of the two mounting portions 31A has an insertion hole 31B. A bolt 30 is inserted into the insertion hole 31B. The flange 31 is fixed to the housing 18 by tightening the bolt 30 to the housing 18. The bolt 30 has a head 30A and a shaft 30B.

[0019] Next, the configuration of the housing 18 will be described in detail. As shown in FIG. 2, the housing 18 has a worm wheel housing member 41 and a worm housing member 42. The worm wheel housing member 41 and the worm housing member 42 are each cylindrical. The worm housing member 42 is connected to the outer peripheral surface of the worm wheel housing member 41. The worm housing member 42 extends in a direction perpendicular to the axis of the worm wheel housing member 41. The interiors of the worm wheel housing member 41 and the worm housing member 42 communicate with each other via a communication hole (not shown). The worm wheel housing member 41 forms the cylindrical portion of the housing 18. The housing 18 is made of, for example, a non-magnetic material. The non-magnetic material includes a non-magnetic metal such as aluminum.

[0020] The worm wheel 22 is rotatably housed inside the worm wheel housing member 41. The worm 21 is rotatably supported inside the worm housing member 42 via a bearing (not shown). The worm wheel 22 and the worm 21 mesh with each other via a communication hole provided inside the housing 18. The worm wheel 22 and the worm 21 are made of, for example, a magnetic material. The magnetic material includes a magnetic metal such as iron.

[0021] 3, the worm wheel housing member 41 has an opening 41A at a first end in the axial direction and an end wall at a second end opposite the first end. The opening 41A opens toward the lower tube 17 along the axis of the worm wheel housing member 41. The outer diameter of the worm wheel housing member 41 is substantially the same as the outer diameter of the flange 31.

[0022] The worm wheel housing member 41 has a cylindrical bearing support portion 43. The bearing support portion 43 is provided on an end wall of the worm wheel housing member 41. The opening 41A and the bearing support portion 43 are arranged coaxially. The interior and exterior of the worm wheel housing member 41 are in communication with each other via the bearing support portion 43.

[0023] The worm wheel housing member 41 has two fastening portions 44. Each fastening portion 44 is a portion to which a bolt 30 is fastened when fixing the flange 31 to the housing 18. Each fastening portion 44 protrudes radially outward from the outer peripheral surface of the worm wheel housing member 41. The two fastening portions 44 are located on opposite sides of the worm wheel housing member 41 in the radial direction. Each fastening portion 44 has a threaded hole 44A. The end face of each fastening portion 44 where the threaded hole 44A opens is flush with the end face of the worm wheel housing member 41 where the opening 41A opens.

[0024] The peripheral edge of the flange 31 abuts against the end face of the worm wheel housing member 41 where the opening 41A opens. The insertion hole 31B of the flange 31 and the screw hole 44A of the housing 18 are aligned with each other. The bolt 30 is inserted into the insertion hole 31B of the flange 31 from the side opposite the housing 18. The bolt 30 is tightened into the fastening portion 44 of the housing 18. This secures the flange 31 to the housing 18. In other words, the lower tube 17 is connected to the housing 18 via the flange 31. The opening 41A of the housing 18 is closed by the flange 31. The flange 31 also serves as a cover that closes the opening 41A of the housing 18.

[0025] The worm wheel housing member 41 rotatably supports the inner shaft 12. The inner shaft 12 passes through the worm wheel housing member 41. The axis of the inner shaft 12 and the axis of the worm wheel housing member 41 are positioned on the same straight line. The inner shaft 12 has an input shaft 12A, an output shaft 12B, and a torsion bar 12C. The input shaft 12A and the output shaft 12B are connected to each other via the torsion bar 12C. The output shaft 12B is a hollow cylinder.

[0026] A first end of the input shaft 12A is connected to the outer shaft 11. A second end of the input shaft 12A is inserted into a first end of the output shaft 12B. A gap exists between the outer peripheral surface of the input shaft 12A and the inner peripheral surface of the output shaft 12B. A plain bearing 12D is interposed between the outer peripheral surface of the input shaft 12A and the inner peripheral surface of the output shaft 12B. The input shaft 12A and the output shaft 12B can rotate relative to each other via the plain bearing 12D.

[0027] A first end of a torsion bar 12C is inserted and fixed to the second end of the input shaft 12A. The second end of the torsion bar 12C is inserted into the inside of the output shaft 12B. A gap exists between the outer circumferential surface of the torsion bar 12C and the inner circumferential surface of the output shaft 12B. The second end of the torsion bar 12C is fixed to the second end of the output shaft 12B. Steering torque applied to the steering wheel 6 is transmitted to the output shaft 12B via the input shaft 12A and the torsion bar 12C. The torsion bar 12C twists in response to the steering torque.

[0028] The worm wheel 22 and the bearing support member 50 are housed inside the worm wheel housing member 41. The worm wheel 22 is fixed to the outer circumferential surface of the output shaft 12B so as to be rotatable integrally therewith. The bearing support member 50 is cylindrical and is mounted so as to be rotatable relative to the outer circumferential surface of the output shaft 12B. The worm wheel 22 and the bearing support member 50 are arranged at intervals along the axial direction of the worm wheel housing member 41. The worm wheel 22 is disposed between the bearing support member 50 and the end wall of the worm wheel housing member 41. The worm wheel housing member 41, the worm wheel 22, and the bearing support member 50 are arranged coaxially.

[0029] As shown in FIGS. 4 and 5, the bearing support member 50 has a cylindrical inner peripheral wall 51, a cylindrical outer peripheral wall 52, and an annular connecting wall 53. The inner circumferential wall 51 is located radially inside the outer circumferential wall 52. The axial position of the inner circumferential wall 51 and the axial position of the outer circumferential wall 52 are slightly different. The connecting wall 53 is a wall portion that extends radially of the bearing support member 50. The connecting wall 53 connects the base end of the inner circumferential wall 51 and the base end of the outer circumferential wall 52. The tip end of the inner circumferential wall 51 and the tip end of the outer circumferential wall 52 face opposite each other in the axial direction. The tip end is the end opposite the base end.

[0030] The connecting wall 53 has an inner flat portion 53A, an inclined portion 53B, and an outer flat portion 53C. The inner flat portion 53A, the inclined portion 53B, and the outer flat portion 53C are connected in this order with respect to the inner circumferential wall 51. The inner flat portion 53A and the outer flat portion 53C extend in a direction perpendicular to the axial direction. The inner circumferential portion of the inner flat portion 53A is connected to the base end of the inner circumferential wall 51. The outer circumferential portion of the outer flat portion 53C is connected to the base end of the outer circumferential wall 52. The outer flat portion 53C is positioned offset toward the tip end of the inner circumferential wall 51 in the axial direction of the bearing support member 50 relative to the inner flat portion 53A. The inclined portion 53B is inclined so that the radially outer portion of the connecting wall 53 approaches the tip end of the inner circumferential wall 51 in the axial direction of the bearing support member 50.

[0031] The inner diameter of the inner circumferential wall 51 is set to be slightly shorter than the outer diameter of the bearing 71. The outer diameter of the outer circumferential wall 52 is set to be slightly longer than the inner diameter of the worm wheel housing member 41. The inner diameter of the inner circumferential wall 51 and the outer diameter of the outer circumferential wall 52 are determined according to the determined press-fit allowance.

[0032] The bearing support member 50 is formed by bending a single plate material. The bearing support member 50 is made of, for example, a magnetic material. The magnetic material includes a magnetic metal such as iron. The bearing support member 50 is formed by, for example, punching out a single metal plate material into a predetermined shape using a press and then plastically deforming it.

[0033] As shown in FIG. 3 , the inner peripheral surface of the bearing support member 50, i.e., the inner peripheral surface of the inner peripheral wall 51, is fitted to the outer peripheral surface of the bearing 71. The outer peripheral surface of the bearing support member 50, i.e., the outer peripheral surface of the outer peripheral wall 52, is fitted to the inner peripheral surface of the worm wheel housing member 41. The bearing support member 50 is press-fitted into the inner peripheral surface of the worm wheel housing member 41 in the mounting direction DW. The mounting direction DW is a direction along the axis of the worm wheel housing member 41 and is the direction in which the bearing support member 50 is inserted into the worm wheel housing member 41. The axial position of the bearing support member 50 relative to the worm wheel housing member 41 is determined by controlling the press-fitting stroke of a press-fitting device (not shown). The inner peripheral wall 51 extends from the connecting wall 53 in the same direction as the mounting direction DW. The outer peripheral wall 52 extends from the connecting wall 53 in the opposite direction to the mounting direction DW. The tip of the inner peripheral wall 51 faces the same direction as the mounting direction DW. The tip end of the outer peripheral wall 52 faces the opposite direction to the mounting direction DW. The base end of the outer peripheral wall 52 is positioned offset in the mounting direction DW with respect to the base end of the inner peripheral wall 51. The inclined portion 53B is inclined so that the radially outer portion is displaced more in the mounting direction DW.

[0034] The output shaft 12B is rotatably supported on the inner peripheral surface of the bearing support portion 43 via a bearing 61. Axial movement of the bearing 61 is restricted. An annular step portion 62 and a retaining ring 63 are provided on the outer peripheral surface of the output shaft 12B. The inner ring of the bearing 61 is interposed between the step portion 62 and the retaining ring 63. An annular protrusion 64 and a retaining ring 65 are provided on the inner peripheral surface of the bearing support portion 43. The outer ring of the bearing 61 is interposed between the protrusion 64 and the retaining ring 65.

[0035] The output shaft 12B is rotatably supported by the inner peripheral wall 51 of the bearing support member 50 via a bearing 71. Axial movement of the bearing 71 is restricted. An annular ridge 72 is provided on the outer peripheral surface of the output shaft 12B. A cylindrical nut member (not shown) is attached to a first end of the output shaft 12B. The inner ring of the bearing 71 is interposed between the ridge 72 and the nut member. The outer ring of the bearing 71 is maintained in a state in which it is elastically pressed radially inward by the inner peripheral wall 51. The outer ring of the bearing 71 is supported by the inner peripheral wall 51.

[0036] The internal space of the worm wheel housing member 41 is divided into two spaces by the bearing support member 50. A sensor 80 is provided in the space between the bearing support member 50 and the flange 31. The sensor 80 includes a torque sensor and a rotation angle sensor. The torque sensor detects the steering torque based on the amount of twist of the torsion bar 12C. The rotation angle sensor detects the rotation angle of the input shaft 12A as the steering angle. Grease is sealed in the space between the bearing support member 50 and the end wall of the worm wheel housing member 41.

[0037] <Functions and Effects of the First Embodiment> The first embodiment provides the following functions and effects. (1-1) As shown in FIG. 6 , the bearing support member 50 is mounted to the worm wheel housing member 41 with the outer peripheral wall 52 facing in the opposite direction to the mounting direction DW. When the bearing support member 50 is press-fitted into the worm wheel housing member 41, the outer peripheral surface of the outer peripheral wall 52 slides against the inner peripheral surface of the worm wheel housing member 41. At this time, sliding resistance acts on the outer peripheral wall 52 in the opposite direction to the mounting direction DW. Due to this sliding resistance, the connecting wall 53 is slightly elastically deformed so as to tilt in the opposite direction to the mounting direction DW, with the connecting portion between the inner peripheral wall 51 and the inner flat portion 53A as a fulcrum. Accordingly, the tip of the outer peripheral wall 52 tilts radially inward, and the outer diameter of the tip of the outer peripheral wall 52 is slightly reduced.

[0038] This reduces the contact area between the outer peripheral surface of the outer peripheral wall 52 and the worm wheel housing member 41. Furthermore, the reduced contact area reduces sliding resistance between the outer peripheral wall 52 and the worm wheel housing member 41. This makes it easier to insert the bearing support member 50 into the worm wheel housing member 41, improving assembly ease. Furthermore, the press-fit load can be reduced. The press-fit load is the force required to press-fit the bearing support member 50 into the worm wheel housing member 41. Therefore, a new steering device 1 can be obtained in which the bearing support member 50 can be easily press-fit into the worm wheel housing member 41.

[0039] (1-2) A so-called reverse input load F may act on the output shaft 12B due to the vehicle running over a curb or the end of the rack shaft 5 hitting the housing 10. End hitting occurs when the end of the rack shaft 5 hits the housing 10. The reverse input load F is a force in the direction opposite to the mounting direction DW. As shown in FIG. 7 , the reverse input load F is transmitted to the inner circumferential wall 51 of the bearing support member 50 via the output shaft 12B and the bearing 71. In response to this reverse input load F, a force acts on the connecting wall 53, tending to tilt the connecting wall 53 in the same direction as the mounting direction DW, with the connecting portion between the inner circumferential wall 51 and the inner flat portion 53A as a fulcrum. Accordingly, a force acts on the outer circumferential wall 52, tending to tilt the tip end of the outer circumferential wall 52 radially outward so as to increase the outer diameter of the tip end of the outer circumferential wall 52.

[0040] As a result, the outer peripheral surface of the outer peripheral wall 52 is pressed more strongly radially outward against the inner peripheral surface of the worm wheel housing member 41. The increased contact load of the outer peripheral surface of the outer peripheral wall 52 against the inner peripheral surface of the worm wheel housing member 41 increases the pull-out load of the bearing support member 50. The pull-out load is a force required to move the bearing support member 50, which is press-fitted into the worm wheel housing member 41, in the direction opposite to the mounting direction DW. Therefore, the increased pull-out load suppresses movement of the bearing support member 50 in the direction opposite to the mounting direction DW. Even if a reverse input load F acts on the output shaft 12B, the bearing support member 50 is held in an appropriate axial position. This provides a novel steering device 1 in which the bearing support member 50 is less likely to fall off in the direction opposite to the mounting direction DW.

[0041] It is also possible to provide the outer peripheral wall 52 so that it faces the same direction as the mounting direction DW. In this case, when the reverse input load F acts on the output shaft 12B, the connecting wall 53 is slightly elastically deformed so as to tilt in the same direction as the mounting direction DW, with the connecting portion between the inner peripheral wall 51 and the inner flat portion 53A as a fulcrum. Accordingly, the tip of the outer peripheral wall 52 tilts radially inward, slightly reducing the outer diameter of the tip of the outer peripheral wall 52. This reduces the contact load between the outer peripheral surface of the outer peripheral wall 52 and the inner peripheral surface of the worm wheel housing member 41, which may reduce the removal load of the bearing support member 50. Therefore, from the perspective of ensuring the removal load of the bearing support member 50, it is preferable that the outer peripheral wall 52 be provided so that it faces the opposite direction to the mounting direction DW.

[0042] (1-3) The bearing support member 50 is maintained in a state where it is press-fitted into the inner peripheral surface of the worm wheel housing member 41. Therefore, there is no need to provide a separate member for maintaining the axial position of the bearing support member 50. Furthermore, there is no need for fastening parts such as bolts to fix the bearing support member 50 to the worm wheel housing member 41. Therefore, an increase in the number of parts of the steering device 1 can be suppressed. Furthermore, the manufacturing cost of the steering device 1 can be reduced.

[0043] (1-4) The bearing support member 50 is maintained in a state where it is press-fitted onto the inner circumferential surface of the worm wheel housing member 41. The inner circumferential surface of the inner circumferential wall 51 is maintained in a state where it is elastically pressed radially inward against the outer circumferential surface of the outer ring of the bearing 71. Ideally, there is no gap between the inner circumferential surface of the inner circumferential wall 51 and the outer circumferential surface of the outer ring of the bearing 71. This makes it difficult for grease to pass through the boundary between the inner circumferential surface of the inner circumferential wall 51 and the outer circumferential surface of the outer ring of the bearing 71. This prevents grease from leaking from the first space between the bearing support member 50 and the end wall of the worm wheel housing member 41 into the second space between the bearing support member 50 and the flange 31.

[0044] Furthermore, the outer peripheral surface of the outer peripheral wall 52 is maintained in a state in which it is elastically pressed radially outward against the inner peripheral surface of the worm wheel housing member 41. Ideally, there is no gap between the outer peripheral surface of the outer peripheral wall 52 and the inner peripheral surface of the worm wheel housing member 41. This makes it difficult for grease to pass through the boundary between the outer peripheral surface of the outer peripheral wall 52 and the inner peripheral surface of the worm wheel housing member 41. This prevents grease from leaking from the first space between the bearing support member 50 and the end wall of the worm wheel housing member 41 into the second space between the bearing support member 50 and the flange 31.

[0045] (1-5) Ideally, there is no gap between the inner peripheral surface of the inner peripheral wall 51 and the outer peripheral surface of the outer ring of the bearing 71. This prevents the occurrence of hitting noises or stick-slip noises between the bearing support member 50 and the bearing 71. Stick-slip noises are abnormal noises that occur when parts rub against each other, in this case, the bearing support member 50 and the bearing 71. This allows the quietness of the steering device 1 to be improved.

[0046] (1-6) The connecting wall 53 has an inclined portion 53B. By adjusting the degree of inclination of the inclined portion 53B, it is possible to adjust the load deflection characteristics of the connecting wall 53. The load deflection characteristics are the relationship between the load acting on a part and the amount of deflection of the part in response to that load.

[0047] (1-7) The bearing support member 50 is formed by bending a single plate material. The plate material is, for example, a magnetic metal plate material. Therefore, the bearing support member 50 can be easily formed by pressing or the like. Furthermore, the weight of the bearing support member 50 can be reduced.

[0048] (1-8) The bearing support member 50 is made of metal. Therefore, for example, when the bearing support member 50 is attached to the worm wheel housing member 41, damage to the bearing support member 50 can be suppressed.

[0049] (1-9) The worm wheel 22, the bearing support member 50, and the sensor 80 can be assembled to the worm wheel housing member 41 from one direction, that is, from the mounting direction DW, thereby improving the ease of assembly.

[0050] <Second embodiment> A second embodiment of the steering device will be described. This embodiment basically has the same configuration as the first embodiment shown in Figures 1 to 7. Therefore, the same members and configurations as those in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0051] The sensor 80 includes a magnetic torque sensor. The torque sensor has a permanent magnet fixed to the input shaft 12A and a yoke unit fixed to the output shaft 12B. The yoke unit is composed of two yokes integrated together via a resin portion. When torque is applied to the input shaft 12A and the torsion bar 12C undergoes torsional deformation, the relative position between the permanent magnet and the yoke in the rotational direction changes. The torque sensor detects the torque applied to the torsion bar 12C based on the change in magnetic flux in the yoke that accompanies the change in the relative position between the permanent magnet and the yoke. The permanent magnet and the two yokes form a magnetic circuit.

[0052] If a magnetic field generating source such as an in-vehicle speaker is present near the steering device 1, there is a risk that magnetic flux generated from the magnetic field generating source will be applied to the sensor 80 via the first magnetic flux path R1. The first magnetic flux path R1 is a path that includes the upper tube 16, the lower tube 17, and the sensor 80. In this case, there is a concern that the torque detection accuracy of the sensor 80 will be reduced due to the sensor 80 being affected by the magnetic field from the magnetic field generating source. Therefore, in this embodiment, the steering device 1 employs the following configuration.

[0053] As shown in FIG. 8, the steering device 1 has two magnetic path members 81. The magnetic path members 81 are used to connect the flange 31 and the outer peripheral wall 51 of the bearing support member 50. The magnetic path members 81 are made of a magnetic metal. The magnetic path members 81 are formed by bending a single metal plate. The magnetic path members 81 are formed by, for example, plastically deforming a single metal plate that has been punched into a predetermined shape by a press.

[0054] The magnetic path member 81 has a first magnetic path portion 81A and a second magnetic path portion 81B. The first magnetic path portion 81A extends in the radial direction of the worm wheel housing member 41. The first magnetic path portion 81A is flat and is sandwiched between the fastening portion 44 of the worm wheel housing member 41 and the mounting portion 31A of the flange 31. The first magnetic path portion 81A is fastened together with the mounting portion 31A and the fastening portion 44 in the axial direction by the bolts 30. A portion of a first end portion of the first magnetic path portion 81A in the radial direction may be exposed to the outside of the housing 18. A second end portion of the first magnetic path portion 81A in the radial direction is located inside the housing 18.

[0055] The second magnetic path portion 81B is inclined so as to approach the inner circumferential surface of the worm wheel housing member 41 as it moves toward the mounting direction DW of the bearing support member 50. A first end of the second magnetic path portion 81B is connected to a second end of the first magnetic path portion 81A. The connecting portion between the first magnetic path portion 81A and the second magnetic path portion 81B is smoothly curved. The second end of the second magnetic path portion 81B is curved radially inward of the worm wheel housing member 41. The curved, convex portion of the second end functions as a contact portion 81C with the bearing support member 50. The contact portion 81C is maintained in a state where it is elastically pressed radially outward against the inner circumferential surface of the outer circumferential wall 52.

[0056] The axial distance between the bearing support member 50 and the worm wheel 22 is set to a distance that allows magnetic flux from an expected magnetic field generation source to pass through. The upper tube 16, the lower tube 17, the flange 31, the magnetic path member 81, the bearing support member 50, and the worm wheel 22 are all formed of magnetic metal. Therefore, the upper tube 16, the lower tube 17, the flange 31, the magnetic path member 81, the bearing support member 50, and the worm wheel 22 can be magnetically coupled to each other, and can form a second magnetic flux path R2. The second magnetic flux path R2 is a magnetic flux path that bypasses the sensor 80.

[0057] Ideally, there is no gap between the flange 31 and the first magnetic path portion 81A. However, the flange 31 and the magnetic member of the sensor 80 are spaced apart in the axial direction. That is, the magnetic resistance between the flange 31 and the first magnetic path portion 81A is smaller than the magnetic resistance between the flange 31 and the magnetic member of the sensor 80. The magnetic member is a permanent magnet and a yoke. Therefore, the magnetic flux applied from outside the steering device 1 flows more easily into the first magnetic path portion 81A than into the magnetic member of the sensor 80.

[0058] The axial distance between the tip of the inner circumferential wall 51 of the bearing support member 50 and the worm wheel 22 is shorter than the axial distance between the flange 31 and the magnetic member of the sensor 80. In addition, the axial distance between the tip of the inner circumferential wall 51 of the bearing support member 50 and the worm wheel 22 is shorter than the axial distance between the magnetic member of the sensor 80 and the worm wheel 22. Therefore, in total, the magnetic resistance of the second magnetic flux path R2 is smaller than the magnetic resistance of the first magnetic flux path R1.

[0059] There may be a small gap between the flange 31 and the first magnetic path portion 81A. However, the gap is shorter than the axial distance between the flange 31 and the magnetic member of the sensor 80. There may also be a small gap between the contact portion 81C and the inner circumferential surface of the outer circumferential wall 52. However, the gap is large enough to allow magnetic flux from an expected magnetic field generation source to pass through.

[0060] <Functions and Effects of the Second Embodiment> In addition to the functions and effects of the first embodiment described in the above sections (1-1) to (1-9), the second embodiment has the following functions and effects.

[0061] (2-1) The magnetic resistance of the second magnetic flux path R2 that does not include the sensor 80 is smaller than the magnetic resistance of the first magnetic flux path R1 that includes the sensor 80. Therefore, the magnetic flux applied from the outside of the steering device 1 passes through the second magnetic flux path R2 that bypasses the radially outer side of the sensor 80, rather than the first magnetic flux path R1 that includes the sensor 80. By preventing the magnetic flux from the magnetic field generation source from being applied to the sensor 80, the detection accuracy of the sensor 80 can be ensured.

[0062] If the bearing support member 50 is made of a non-magnetic material such as synthetic resin, it is difficult to form the second magnetic flux path R2 that bypasses the radially outer side of the sensor 80. In this case, the magnetic flux from the magnetic field generation source is likely to pass through the first magnetic flux path R1 that includes the sensor 80.

[0063] (2-2) A second magnetic flux path R2 that bypasses the sensor 80 is formed by using magnetic members such as the flange 31, the bearing support member 50, and the worm wheel 22. It is only necessary to provide a magnetic path member 81 for magnetically coupling the flange 31 and the bearing support member 50. This reduces production costs compared to, for example, providing a magnetic shield that surrounds the sensor 80. The manufacturing process for the magnetic shield is complex, which may increase production costs. According to this embodiment, by magnetically coupling magnetic members and components present around the sensor 80, the steering device 1 can function as a magnetic shield that blocks the effects of external magnetic fields on the sensor 80.

[0064] <Other embodiments> The first and second embodiments may be modified as follows. In the first embodiment, the bearing support member 50 and the housing 18 may be made of synthetic resin. Synthetic resin materials are cheaper than metal materials. This allows the production cost of the steering device 1 to be reduced.

[0065] In the first embodiment, the inclined portion 53B of the connecting wall 53 may be omitted. In this case, the connecting wall 53 is a flat wall portion extending in the radial direction. In the second embodiment, only one magnetic path member 81 may be provided, or three or more magnetic path members 81 may be provided.

[0066] In the second embodiment, the magnetic path member 81 may be omitted depending on the product specifications. In this case, for example, the axial distance between the flange 31 and the outer peripheral wall 52 is shortened to an extent that the flange 31 and the outer peripheral wall 52 can be magnetically coupled. For example, the outer peripheral wall 52 may be extended in the direction opposite to the mounting direction DW. The extent to which the flange 31 and the outer peripheral wall 52 can be magnetically coupled means an extent to which the magnetic flux from the magnetic flux generating source can pass from the flange 31 to the outer peripheral wall 52.

[0067] In the second embodiment, if the magnetic path member 81 is omitted, the housing 18 may be made of a magnetic metal. In this case, the magnetic flux from the magnetic flux generating source passes through, for example, the flange 31, the worm wheel housing member 41, and the bearing support member 50 in that order.

[0068] In the second embodiment, the second magnetic flux path R2 may include a component that comes into contact with the output shaft 12B. For example, if the outer ring, inner ring, and balls of the bearing 71 are made of a magnetic metal, the bearing 71 may form part of the second magnetic flux path R2.

[0069] Depending on the product specifications, the steering device 1 may not need to be provided with a structure for adjusting the vertical position of the steering wheel 6 or a structure for adjusting the axial position of the steering wheel 6. In this case, a single, non-extendable support tube is provided in place of the upper tube 16 and the lower tube 17. The steering shaft 2 is rotatably supported by this single support tube. The housing 18 is fixed to the frame 14 of the vehicle body. A structure can be adopted in which the support portion 18A and the support shaft 18B are omitted from the housing 18. A locking mechanism for selectively locking and unlocking the swinging of the steering column 15 about the support shaft 18B and the extension and retraction of the steering column 15 is also not required.

[0070] The steering device 1 may be a steer-by-wire type steering device. In this case, power transmission between the steering wheel 6 and the steered wheels is separated. The motor 19 functions as a reaction motor. The reaction motor generates a steering reaction torque that is applied to the steering shaft 2 of the vehicle. The steering reaction torque is a torque in the opposite direction to the steering direction of the steering wheel 6.

Claims

1. a cylindrical support tube having a flange and rotatably supporting the steering shaft; a reducer configured to impart torque to the steering shaft; a housing having a cylindrical portion that accommodates the reducer, the cylindrical portion being coaxially connected to the flange; a bearing support member fitted to an inner peripheral surface of the cylindrical portion from an installation direction that is an axial direction, the bearing support member through which the steering shaft passes; a bearing interposed between an outer circumferential surface of the steering shaft and an inner circumferential surface of the bearing support member, the bearing support member has an inner peripheral wall that fits onto an outer peripheral surface of the bearing, an outer peripheral wall that fits onto an inner peripheral surface of the cylindrical portion, and a connecting wall that radially connects the inner peripheral wall and the outer peripheral wall, the inner circumferential wall has a base end connected to the connecting wall and extends from the connecting wall in the same direction as the mounting direction, the outer peripheral wall has a base end connected to the connecting wall and extends from the connecting wall in a direction opposite to the mounting direction, the bearing support member is fixed to the inside of the housing only by the fitting; A steering device in which the housing does not include a structure for regulating the axial position of the bearing support member.

2. The steering device according to claim 1 , wherein the connecting wall has an inclined portion that is inclined so as to be displaced more in the mounting direction as it becomes more radially outward.

3. 3. The steering apparatus according to claim 1, wherein the bearing support member is formed by bending a single plate material.

4. 4. The steering device according to claim 1, wherein the bearing support member is made of metal.

5. a magnetic sensor disposed in a space between the flange and the bearing support member inside the housing; the flange and the bearing support member are made of a magnetic metal, and the housing is made of a non-magnetic metal; 5. The steering apparatus according to claim 1, wherein the flange and the bearing support member are configured to form a magnetic flux path that bypasses the periphery of the sensor.

6. 6. The steering apparatus according to claim 5, further comprising a magnetic path member made of a magnetic metal that connects the flange and the outer peripheral wall.

7. the reducer has a worm wheel that rotates integrally with the steering shaft and a worm that meshes with the worm wheel, the housing has a worm wheel housing member in which the worm wheel is housed and a worm housing member in which the worm is housed, 7. The steering device according to claim 1, wherein the cylindrical portion is the worm wheel housing member.

Images