Steering device

Abstract

The present application relates to a steering device having a cylindrical support cylinder (17) that supports a steering shaft (2) so as to be rotatable, a speed reducer (20) that applies a torque to the steering shaft (2), and a housing (18) having a cylindrical portion (41) that houses the speed reducer (20). A flange (31) of the support cylinder (17) and the cylindrical portion (41) are coaxially arranged and are coupled to each other by a bolt (30). A bearing support member (50) is fitted to an inner peripheral surface of the cylindrical portion (41). The steering shaft (2) penetrates the bearing support member (50). A bearing (71) is arranged between an outer peripheral surface of the steering shaft (2) and an inner peripheral surface of the bearing support member (50). The bearing support member (50) has deformation permitting portions (55, 56, 59) configured to permit elastic deformation in a radial direction of the bearing support member (50).

Description

Technical Field

[0001] This disclosure relates to steering mechanisms. Background Technology

[0002] Conventional electric power steering systems exist that utilize motors to assist steering maneuvers. For example, the steering system in Patent Document 1 includes a motor and a metal housing. The housing houses a torque sensor and a worm gear mechanism. The motor generates a torque corresponding to the steering torque detected by the torque sensor. The motor's torque is transmitted to the steering shaft via the worm gear mechanism.

[0003] The housing comprises a worm housing component and a sensor housing component. The worm housing component houses the worm gear mechanism. The sensor housing component houses the torque sensor. The worm housing component and the sensor housing component are axially fitted together on the steering shaft. The steering shaft is rotatably supported on the worm housing component and the sensor housing component via bearings.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2020-90139 Summary of the Invention

[0005] In recent years, customer requirements for steering systems have become increasingly diverse, based on vehicle specifications and other factors. To meet these requirements, extensive research and development are underway regarding the structure of steering systems. Sometimes, steering systems with entirely new structures are also needed.

[0006] One aspect of the steering device disclosed herein includes: a cylindrical support cylinder having a flange and supporting a steering shaft for rotation; a reducer configured to apply torque to the steering shaft; a housing having a cylindrical portion housing the reducer, the cylindrical portion being coaxially arranged with the flange; bolts connecting the flange and the cylindrical portion; a bearing support member fitting into the inner circumferential surface of the cylindrical portion and through which the steering shaft passes; and a bearing located between the outer circumferential surface of the steering shaft and the inner circumferential surface of the bearing support member. The bearing support member has a deformation-allowing portion configured to allow radial elastic deformation of the bearing support member. Attached Figure Description

[0007] Figure 1 This is a schematic diagram illustrating the structure of one embodiment of the steering device.

[0008] Figure 2 yes Figure 1 A 3D view of the steering column.

[0009] Figure 3 yes Figure 2 A cross-sectional view of the connection between the housing and the lower tube.

[0010] Figure 4Viewed from an oblique angle Figure 3 A three-dimensional view of the bearing support components.

[0011] Figure 5 Viewed from below at an angle Figure 3 A three-dimensional view of the bearing support components.

[0012] Figure 6 yes Figure 3 A three-dimensional cross-sectional view of the bearing support component.

[0013] Figure 7 yes Figure 3 A three-dimensional cross-sectional view of the bearing support component.

[0014] Figure 8 yes Figure 3 A cross-sectional view of the bearing support component.

[0015] Figure 9 This is a cross-sectional view of the bearing support component involved in other embodiments.

[0016] Figure 10 This is a cross-sectional view of the bearing support component involved in other embodiments. Detailed Implementation

[0017] One embodiment of the steering device will be described.

[0018] like Figure 1 As shown, the steering device 1 includes a steering shaft 2, an intermediate shaft 3, a pinion shaft 4, and a rack shaft 5. A steering wheel 6 is connected to the first end of the steering shaft 2. The first end of the intermediate shaft 3 is connected to the second end of the steering shaft 2 via a universal joint 7. The 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 the rack shaft 5. The rack shaft 5 is supported inside a housing 10 of a frame 9 fixed to the vehicle body. The rack shaft 5 is movable to the left or right relative to the vehicle's direction of travel. Both ends of the rack shaft 5 are connected to the left and right steering wheels (not shown) via tie rods (not shown).

[0019] 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, for example, by a spline connection. The outer shaft 11 and the inner shaft 12 can rotate as a whole and can move relative to each other along their respective axes. The steering shaft 2 is arranged so that the steering wheel 6 is facing upward and tilted relative to the longitudinal direction of the vehicle.

[0020] The steering system 1 has a steering column 15. A steering shaft 2 is inserted into 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 mounted on two frames 13 and 14 provided on the vehicle body. One frame 13 is located further rearward than the other frame 14 in the longitudinal direction of the vehicle.

[0021] 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 the 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 mounted to the frame 13 of the vehicle body via the column bracket 17A.

[0022] The upper tube 16 and the lower tube 17 form a support cylinder that supports the steering shaft 2 so that it can rotate.

[0023] The housing 18 is connected to the second end of the lower tube 17. The housing 18 has two support portions 18A (in... Figure 1 Only one is shown in the figure, along with a support shaft 18B. Two support portions 18A are provided on the side of the housing 18 opposite to the lower tube 17. The two support portions 18A are opposite to 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 the bracket 24 of the frame 14 fixed to the vehicle body.

[0024] A steering assist motor 19 is disposed outside the housing 18. A reducer 20 is housed inside the housing 18. The reducer 20 slows the rotation of the motor 19 and transmits this reduced rotation to the inner shaft 12. The reducer 20 is a worm gear reducer having a worm 21 and a worm wheel 22. The worm 21 is rotatably connected to the output shaft of the motor 19 (not shown). The axis of the worm 21 and the axis of the output shaft of the motor 19 are on the same straight line. The worm wheel 22 meshes with the worm 21. The worm wheel 22 is configured to rotate integrally with the inner shaft 12. The axis of the worm wheel 22 and the axis of the inner shaft 12 are on the same straight line.

[0025] The steering system 1 has a locking mechanism (not shown). The locking mechanism selectively locks and unlocks the swing and extension / retraction of the steering column 15 around the support shaft 18B by operating a lever (not shown). Unlocking the lever allows the steering column 15 to swing relative to the column bracket 17A around the support shaft 18B. After unlocking the lever, the vertical position of the steering wheel 6 can be adjusted by moving it up or down. Additionally, unlocking the lever allows the upper tube 16 to move axially relative to the lower tube 17 along the steering shaft 2. After unlocking the lever, the axial position of the steering wheel 6 can be adjusted by moving it axially along the steering shaft 2.

[0026] Next, the structure of the lower tube 17 will be explained in detail.

[0027] like Figure 2 As shown, the lower tube 17 has a flange 31. The flange 31 is located at the second end of the lower tube 17. The second end of the lower tube 17 is the end opposite to the first end into which the upper tube 16 is inserted. The flange 31 is an annular plate. The flange 31 has two mounting portions 31A. The two mounting portions 31A are located 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 each other in the radial direction of the flange 31. Figure 3 As shown, each of the two mounting portions 31A has a through hole 31B. The through hole 31B is for inserting a bolt 30. By fastening the bolt 30 to the housing 18, the flange 31 is fixed to the housing 18. The bolt 30 has a head 30A and a shaft portion 30B.

[0028] Next, the structure of the housing 18 will be described in detail.

[0029] like Figure 2 As shown, the housing 18 has a worm gear housing component 41 and a worm housing component 42. Both the worm gear housing component 41 and the worm housing component 42 are cylindrical. The worm housing component 42 is connected to the outer peripheral surface of the worm gear housing component 41. The worm housing component 42 extends in a direction orthogonal to the axis of the worm gear housing component 41. The interiors of the worm gear housing component 41 and the worm housing component 42 are interconnected via a connecting hole (not shown). The worm gear housing component 41 constitutes the cylindrical portion of the housing 18. The housing 18 is made of a metal such as alumina.

[0030] The worm gear 22 is rotatably housed inside the worm gear housing component 41. The worm 21 is rotatably supported inside the worm housing component 42 via a bearing (not shown). The worm gear 22 and the worm 21 mesh with each other via a pre-existing communication hole provided inside the housing 18.

[0031] like Figure 3As shown, the worm gear housing component 41 has an opening 41A at a first axial end and an end wall at a second end opposite to the first end. The opening 41A opens towards the lower tube 17 along the axis of the worm gear housing component 41. The outer diameter of the worm gear housing component 41 is substantially the same as the outer diameter of the flange 31.

[0032] The worm gear housing component 41 has a cylindrical bearing support portion 43. The bearing support portion 43 is disposed on the end wall of the worm gear housing component 41. The opening portion 41A and the bearing support portion 43 are coaxially arranged. The interior and exterior of the worm gear housing component 41 are interconnected via the bearing support portion 43.

[0033] The worm gear housing component 41 has two fastening portions 44. Each fastening portion 44 is used to fasten the bolt 30 when the flange 31 is fixed to the housing 18. Each fastening portion 44 protrudes radially outward from the outer peripheral surface of the worm gear housing component 41. The two fastening portions 44 are located on opposite sides of each other in the radial direction of the worm gear housing component 41. Each fastening portion 44 has a threaded hole 44A. The end face of each fastening portion 44 with the threaded hole 44A is coplanar with the end face of the worm gear housing component 41 with the opening 41A.

[0034] The periphery of flange 31 abuts against the end face of worm gear housing component 41 with opening 41A. The insertion hole 31B of flange 31 coincides with the threaded hole 44A of housing 18. Bolt 30 is inserted into the insertion hole 31B of flange 31 from the side opposite to housing 18. Bolt 30 is fastened to fastening portion 44 of housing 18. Thus, flange 31 is fixed to housing 18. That is, lower tube 17 is connected to housing 18 via flange 31. Furthermore, opening 41A of housing 18 is blocked by flange 31. Flange 31 also acts as a cover to close opening 41A of housing 18.

[0035] The worm gear housing component 41 supports the inner shaft 12 for rotation. The inner shaft 12 passes through the worm gear housing component 41. The axis of the inner shaft 12 and the axis of the worm gear housing component 41 are 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.

[0036] The first end of the input shaft 12A is connected to the outer shaft 11. The second end of the input shaft 12A is inserted into the first end of the output shaft 12B. There is a gap between the outer circumferential surface of the input shaft 12A and the inner circumferential surface of the output shaft 12B. A sliding bearing 12D is located between the outer circumferential surface of the input shaft 12A and the inner circumferential surface of the output shaft 12B. The input shaft 12A and the output shaft 12B can rotate relative to each other via the sliding bearing 12D.

[0037] The first end of the torsion bar 12C is fixed to the second end of the input shaft 12A in an inserted state. The second end of the torsion bar 12C extends into the interior 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. The 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 according to the steering torque.

[0038] The worm gear housing component 41 houses the worm gear 22 and the bearing support component 50. The worm gear 22 is integrally and rotatably fixed to the outer peripheral surface of the output shaft 12B. The bearing support component 50 is cylindrical and is rotatably mounted relative to the outer peripheral surface of the output shaft 12B. The worm gear 22 and the bearing support component 50 are arranged with a gap between them along the axial direction of the worm gear housing component 41. The worm gear 22 is disposed between the bearing support component 50 and the end wall of the worm gear housing component 41. The worm gear housing component 41, the worm gear 22, and the bearing support component 50 are coaxially arranged.

[0039] like Figure 4 and Figure 5 As shown, the bearing support member 50 has a peripheral wall 50A and an end wall 50B extending radially inward from a first axial end of the peripheral wall 50A. The end wall 50B is a wall portion that extends radially along the bearing support member 50. The peripheral wall 50A has a second end, which serves as an open end, on the side opposite to the first end. The bearing support member 50 has a through hole 51. The through hole 51 passes through the center of the end wall 50B of the bearing support member 50. An annular inner protrusion 52 is provided on the inner circumferential surface of the end wall 50B. The inner protrusion 52 extends circumferentially along the inner circumferential surface of the bearing support member 50, and more specifically, along the inner circumferential surface of the end wall 50B. The inner protrusion 52 is coplanar with respect to the inner surface of the end wall 50B of the bearing support member 50. In addition, the bearing support member 50 has an annular outer protrusion 53. The outer protrusion 53 is provided at the axial end of the bearing support member 50, and more specifically, at the second end of the peripheral wall 50A. The outer protrusion 53 extends circumferentially along the outer peripheral surface of the peripheral wall 50A. The outer protrusion 53 is inclined such that it approaches the flange 31 as it moves radially outward toward the bearing support member 50. The bearing support member 50 is, for example, made of synthetic resin. That is, the coefficients of linear expansion of the bearing support member 50 and the housing 18 are different. The coefficient of linear expansion of synthetic resin has a larger value than that of metal.

[0040] like Figure 3As shown, the outer peripheral surface of the bearing support member 50, i.e., the outer peripheral surface of the end wall 50B, is embedded in the inner peripheral surface of the worm gear housing member 41. The bearing support member 50 has a corner portion 54 formed at the intersection of the end wall 50B and the peripheral wall 50A. The corner portion 54 abuts against the annular stepped portion 45 provided on the inner peripheral surface of the worm gear housing member 41 in the mounting direction DW. The mounting direction DW is along the axis of the worm gear housing member 41 and is the direction in which the bearing support member 50 is inserted relative to the worm gear housing member 41. The stepped portion 45 is provided at the portion where the inner diameter of the worm gear housing member 41 changes and extends circumferentially along the inner peripheral surface of the worm gear housing member 41. By abutting against the stepped portion 45, the movement of the bearing support member 50 relative to the worm gear housing member 41 in the mounting direction DW is restricted. The outer protrusion 53 is engaged with the annular groove 46 provided on the inner peripheral surface of the worm gear housing member 41. The groove 46 extends circumferentially along the inner circumferential surface of the worm gear housing component 41. The outer protrusion 53 abuts against the groove 46 in a direction opposite to the mounting direction DW, thereby restricting the movement of the bearing support component 50 relative to the worm gear housing component 41 in a direction opposite to the mounting direction DW.

[0041] The output shaft 12B is rotatably supported on the inner circumferential surface of the bearing support portion 43 via the bearing 61. The bearing 61 is in a state where axial movement is restricted. An annular stepped portion 62 and a retaining ring 63 are provided on the outer circumferential surface of the output shaft 12B. The inner ring of the bearing 61 is located between the stepped portion 62 and the retaining ring 63. An annular protrusion 64 and a retaining ring 65 are provided on the inner circumferential surface of the bearing support portion 43. The outer ring of the bearing 61 is located between the protrusion 64 and the retaining ring 65.

[0042] The output shaft 12B is rotatably supported by the through hole 51 of the bearing support member 50 via the bearing 71. The bearing 71 is in a state where axial movement is restricted. An annular protrusion 72 is provided on the outer peripheral surface of the output shaft 12B. The inner ring of the bearing 71 abuts against the protrusion 72 in the mounting direction DW. The outer ring of the bearing 71 abuts against the annular inner protrusion 52 of the bearing support member 50 in the opposite direction to the mounting direction DW.

[0043] In addition to the corner 54 of the bearing support member 50 abutting against the annular stepped portion 45, the annular inner protrusion 52 also abuts against the outer ring of the bearing 71 in the mounting direction DW, thereby restricting the movement of the bearing support member 50 in the mounting direction DW.

[0044] The internal space of the worm gear housing component 41 is divided into two spaces by the bearing support component 50. A sensor 80 is disposed in the space between the bearing support component 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 torsion 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 component 50 and the end wall of the worm gear housing component 41.

[0045] Next, the structure of the bearing support component 50 will be further explained.

[0046] like Figure 6 As shown, the bearing support component 50 has a first slit 55 and a second slit 56. The first slit 55 and the second slit 56 are disposed on the end wall 50B. More specifically, the first slit 55 and the second slit 56 are disposed on the first end face of the end wall 50B in the axial direction. The first end face is the end face of the end wall 50B on the side of the peripheral wall 50A that protrudes axially. The first end face is orthogonal to the axial direction.

[0047] The first slit 55 and the second slit 56 are annular grooves extending circumferentially. The first slit 55 and the second slit 56 open in a direction opposite to the mounting direction DW of the bearing support member 50. The first slit 55 and the second slit 56 are concentrically arranged with respect to the axis of the bearing support member 50.

[0048] The first slit 55 is located radially outside the second slit 56. The first slit 55 extends circumferentially along the outer peripheral surface of the bearing support member 50. The first slit 55 also extends along the inner peripheral surface of the peripheral wall 50A. The first slit 55 has annular inner wall surfaces that are radially opposite each other. The radially outer inner wall surfaces are continuous with the inner peripheral surface of the peripheral wall 50A without steps.

[0049] The second slit 56 is located radially inside the first slit 55. The second slit 56 surrounds the through hole 51. The second slit 56 extends circumferentially along the inner circumferential surface of the through hole 51. The inner circumferential surface of the through hole 51 is also the inner circumferential surface of the bearing support member 50. By providing the second slit 56 in the end wall 50B, an annular inner circumferential wall 50C is formed.

[0050] The first slit 55 and the second slit 56 constitute a deformation-allowing part that allows radial elastic deformation of the bearing support member 50.

[0051] like Figure 7As shown, the bearing support member 50 has a plurality of recesses 57. The recesses 57 are provided on the second end face of the axially inclined end wall 50B. The second end face is the axially inclined end face opposite to the first end face. The recesses 57 are spaced apart in the circumferential direction of the end wall 50B. Viewed axially, the recesses 57 are located in the region between the first slit 55 and the second slit 56 in the second end face.

[0052] The bearing support member 50 has a plurality of ribs 58. The ribs 58 are for reinforcement. The plurality of ribs 58 are provided by providing a plurality of recesses 57 in the end wall 50B. The ribs 58 are part of the bearing support member 50 between two adjacent recesses 57 in the circumferential direction. The ribs 58 are walls that extend radially along the end wall 50B. The ribs 58 connect the radially outer portion of the end wall 50B provided with the first slit 55 to the radially inner portion of the end wall 50B provided with the second slit 56.

[0053] like Figure 8 As shown, the resin thickness of the bearing support member 50 is approximately uniform. The dimensions of each part of the bearing support member 50 are set from the viewpoint of making the resin thickness of the bearing support member 50 uniform. The dimensions of each part include, for example, the following seven dimensions (A1) to (A7).

[0054] A1. Depth of the first slit, 55 mm

[0055] A2. Width of the first slit 55

[0056] A3. Depth of the second slit 56

[0057] A4. Width of the second slit 56

[0058] A5. Depth of recess 57

[0059] A6. Width of recess 57

[0060] A7. Circumferential length of recess 57

[0061] Furthermore, the depth is an axial dimension, and the width is a radial dimension. By adjusting dimensions (A1) to (A7), the resin thickness of the bearing support member 50, which has a first slit 55, a second slit 56, and a recess 57, can be adjusted. By adjusting dimension (A7), the thickness of the circumferential length of the rib 58 can be adjusted.

[0062] <Effects of the Implementation Method>

[0063] This implementation method achieves the following effects.

[0064] (1) Conventionally, there are steering devices with housings as follows. Existing housings include, for example, a worm gear housing component that houses a reducer and a cylindrical sensor housing component that houses a sensor. The steering shaft is supported by bearings provided in the worm gear housing component and bearings provided in the sensor housing component, enabling it to rotate. A cylindrical component that encloses the steering shaft is mounted in the sensor housing component. This cylindrical component corresponds to the lower tube 17 in this embodiment.

[0065] In contrast, according to this embodiment, the bearing support member 50, which serves as a component for supporting the bearing 71, and the flange 31, which serves as a component for connecting the lower tube 17 to the housing 18, are configured as independent and separate members. The bearing support member 50 is installed inside the worm gear housing member 41. The lower tube 17 is fixed to the worm gear housing member 41 via the flange 31. Thus, according to this embodiment, a new steering device 1 that does not have a structure equivalent to that of a conventional sensor housing member can be obtained.

[0066] (2) Existing worm gear housing components and sensor housing components are made of metals such as alumina, and are therefore expensive. In this respect, in this embodiment, the bearing 71 is supported by a bearing support component 50 made of synthetic resin instead of the existing sensor housing component. Compared with the case of setting an existing sensor housing component, the product cost can be reduced by the amount of metal used in the housing.

[0067] (3) The lower tube 17 is directly fixed to the worm gear housing component 41 via a plate-shaped flange 31. Therefore, compared with the case where the lower tube 17 is installed on the worm gear housing component 41 via a structure equivalent to the existing sensor housing component, the size of the steering column 15 can be reduced in the axial direction.

[0068] (4) The bearing support component 50 is maintained in a state of being fitted with the inner circumferential surface of the worm gear housing component 41. There is no need for fastening components such as bolts to fix the bearing support component 50 to the worm gear housing component 41. Therefore, the number of components can be reduced.

[0069] (5) The bearing support member 50 is maintained in a state where axial movement is restricted. The outer protrusion 53, which serves as an engaging portion, engages with the groove 46 in the axial direction of the bearing support member 50, thereby restricting movement of the bearing support member 50 in the direction opposite to the mounting direction DW. Furthermore, the corner portion 54 and the stepped portion 45, which also serve as engaging portions, engage in the axial direction of the bearing support member 50, or the inner protrusion 52 engages with the outer ring of the bearing 71 in the axial direction of the bearing support member 50, thereby restricting movement of the bearing support member 50 in the mounting direction DW. Therefore, it is possible to prevent the bearing support member 50 from detaching from the bearing 71 in the axial direction. Thus, the bearing support member 50 is maintained in a state where it properly supports the bearing 71. In addition, since the bearing support member 50 can be assembled to the worm gear housing member 41 from the mounting direction DW in a single operation, assemblability is improved.

[0070] (6) The coefficients of linear expansion of the bearing support component 50 and the housing 18 are different. Therefore, the degree of dimensional change with respect to changes in ambient temperature differs between the bearing support component 50 and the housing 18. For example, if the coefficient of linear expansion of the bearing support component 50 is greater than that of the housing 18, the bearing support component 50 may shrink more than the housing 18 as the ambient temperature decreases. As the bearing support component 50 shrinks radially, a gap may form between the outer circumferential surface of the bearing support component 50 and the inner circumferential surface of the worm gear housing component 41, which is a concern.

[0071] In this respect, according to this embodiment, even if a gap exists between the outer peripheral surface of the bearing support member 50 and the inner peripheral surface of the worm gear housing member 41, the movement of the bearing support member 50 in the direction opposite to the mounting direction DW is restricted as long as the engagement between the outer protrusion 53 and the groove 46 is not released. Furthermore, the movement of the bearing support member 50 in the mounting direction DW is restricted as long as the engagement between the corner portion 54 and the stepped portion 45 or the engagement between the inner protrusion 52 and the outer ring of the bearing 71 is not released. Therefore, the bearing support member 50 is maintained in the state of supporting the bearing 71.

[0072] (7) Since the worm gear 22, bearing support member 50, and sensor 80 can be arranged inside the housing 18, it is not necessary to house the sensor in a sensor housing member that is different from the existing worm housing member. Therefore, assemblability is improved. In addition, since the worm gear 22, bearing support member 50, and sensor 80 can be assembled to the worm gear housing member 41 from one direction from the mounting direction DW, assemblability is improved.

[0073] (8) The bearing support member 50 has an annular first slit 55. The first slit 55 extends circumferentially along the inner circumferential surface of the peripheral wall 50A. Because the first slit 55 exists radially inward on the peripheral wall 50A, the peripheral wall 50A readily undergoes radial elastic deformation. When the bearing support member 50 is assembled to the worm gear housing member 41, the outer protrusion 53 contacts the inner circumferential surface of the worm gear housing member 41, thereby applying a radially inward force to the peripheral wall 50A via the outer protrusion 53. The peripheral wall 50A, subjected to this force, elastically deforms radially inward about its first end as a fulcrum, causing the outer protrusion 53 to retract radially inward. Assemblability is improved because the bearing support member 50 can be easily inserted into the worm gear housing member 41. Cracks in the peripheral wall 50A of the bearing support member 50 can also be suppressed.

[0074] (9) Furthermore, when the bearing support member 50 is assembled into the worm gear housing member 41, as the bearing support member 50 moves in the mounting direction DW, the front end of the outer protrusion 53 slides relative to the inner circumferential surface of the worm gear housing member 41 along the mounting direction DW. The peripheral wall 50A elastically returns to its original position when the front end of the outer protrusion 53 reaches the groove 46. Thus, the front end of the outer protrusion 53 is embedded in the groove 46. Therefore, the front end of the outer protrusion 53 can be assembled into the groove 46 simply by inserting the bearing support member 50 into the worm gear housing member 41 from the mounting direction DW. Therefore, the assemblability of the bearing support member 50 relative to the worm gear housing member 41 is improved.

[0075] (10) With the front end of the outer protrusion 53 embedded in the groove 46, the outer peripheral surface of the peripheral wall 50A is maintained in contact with the inner peripheral surface of the worm gear housing component 41. Ideally, there is no gap between the outer peripheral surface of the peripheral wall 50A and the inner peripheral surface of the worm gear housing component 41. Therefore, grease is unlikely to pass through the boundary between the outer peripheral surface of the peripheral wall 50A and the inner peripheral surface of the worm gear housing component 41. Therefore, leakage of grease from the first space between the bearing support component 50 and the end wall of the worm gear housing component 41 to the second space between the bearing support component 50 and the flange 31 can be suppressed.

[0076] (11) The bearing support member 50 has an annular second slit 56. The second slit 56 extends circumferentially along the inner peripheral surface of the insertion hole 51. By providing the second slit 56, an annular inner peripheral wall 50C is formed. Because the second slit 56 exists on the radially outer side of the inner peripheral wall 50C, the inner peripheral wall 50C can easily deform elastically in the radial direction. The inner peripheral wall 50C is the wall that forms the insertion hole 51. When the bearing support member 50 is assembled into the interior of the worm gear housing member 41, the inner peripheral wall 50C of the bearing support member 50 deforms elastically in the radial direction, thereby easily fitting the inner peripheral surface of the insertion hole 51 into the outer peripheral surface of the outer ring of the bearing 71. In addition, it is possible to suppress the generation of cracks in the peripheral portion of the insertion hole 51 of the bearing support member 50. Therefore, the assemblability of the bearing support member 50 relative to the worm gear housing member 41 is improved.

[0077] (12) The inner circumferential surface of the through-hole 51 is maintained in contact with the outer circumferential surface of the outer ring of the bearing 71. Ideally, there is no gap between the inner circumferential surface of the through-hole 51 and the outer circumferential surface of the outer ring of the bearing 71. Therefore, knocking noise or stick-slip noise generated between the bearing support member 50 and the bearing 71 can be suppressed. Stick-slip noise is the abnormal noise generated by the friction between the components, here the bearing support member 50 and the bearing 71. Therefore, the quietness of the steering device 1 can be improved. In addition, grease is difficult to pass through the boundary between the inner circumferential surface of the through-hole 51 and the outer circumferential surface of the outer ring of the bearing 71. Therefore, grease leakage from the first space between the bearing support member 50 and the end wall of the worm gear housing member 41 to the second space between the bearing support member 50 and the flange 31 can be suppressed.

[0078] (13) The bearing support component 50 is a resin molded article manufactured by injection molding. Injection molding is a molding technique that obtains a resin molded article by injecting molten resin into a mold, cooling and solidifying the molten resin. In injection molding, if there is a difference in the thickness of the resin molded article, the degree of shrinkage will be different, thus producing shrinkage marks in the thick-walled portion. Shrinkage marks refer to the phenomenon that, during the process of the resin molded article being cooled and solidified inside the mold, the thick-walled portion shrinks more than the thin-walled portion, resulting in a depression on the surface of the thick-walled portion.

[0079] The bearing support component 50 has a first slit 55, a second slit 56, and a recess 57. The first slit 55, the second slit 56, and the recess 57 are also so-called thinning portions used to make the resin thickness of the bearing support component 50 uniform. By adjusting the dimensions of the first slit 55, the second slit 56, and the recess 57, the resin thickness of the bearing support component 50 can be made to be nearly uniform. Therefore, the formation of shrinkage marks is suppressed in the bearing support component 50. Furthermore, the moldability and productivity of the bearing support component 50 are improved.

[0080] (14) Because the bearing support member 50 is provided with the first slit 55, the second slit 56 and the recess 57, the strength of the bearing support member 50 may be reduced. This reduction in strength is compensated by the multiple ribs 58. That is, the strength of the bearing support member 50 can be ensured by the multiple ribs 58.

[0081] <Other Implementation Methods>

[0082] Furthermore, this implementation method can also be modified and implemented as follows.

[0083] The materials of the bearing support component 50 and the housing 18 may vary depending on the product specifications. For example, the bearing support component 50 may be made of metal, and the housing 18 may be made of synthetic resin.

[0084] • The bearing support component 50 and the housing 18 can also be formed of the same material. In this case, the coefficient of linear expansion of the bearing support component 50 and the housing 18 is the same. Therefore, the bearing support component 50 and the housing 18 change dimensions in the same way with changes in atmospheric temperature. Therefore, it is not easy for a gap to be generated between the outer peripheral surface of the bearing support component 50 and the inner peripheral surface of the worm gear housing component 41.

[0085] • Alternatively, a structure can be adopted in which the stepped portion 45 is omitted from the worm gear housing component 41. Even so, the movement of the bearing support component 50 in the mounting direction DW can be restricted by the interlocking of the inner protrusion 52 of the bearing support component 50 with the outer ring of the bearing 71.

[0086] • Alternatively, a structure can be adopted in which the annular inner protrusion 52 is omitted from the bearing support member 50. Even so, the movement of the bearing support member 50 in the mounting direction DW can be restricted by the interlocking of the corner portion 54 of the bearing support member 50 with the stepped portion 45 of the worm gear housing member 41.

[0087] Depending on the product specifications, the steering device 1 may not include structures for adjusting the vertical position of the steering wheel 6 or for adjusting its axial position. In this case, a single, non-retractable support cylinder is used instead of the upper tube 16 and lower tube 17. The steering shaft 2 is supported by this single support cylinder and is rotatable. Furthermore, the housing 18 is fixed to the vehicle frame 14. A structure that omits the support portion 18A and the support shaft 18B from the housing 18 can be used. Additionally, a locking mechanism for selectively locking and unlocking the steering column 15's swing centered on the support shaft 18B and the steering column 15's extension and retraction is unnecessary.

[0088] ·like Figure 10As shown, the first slit 55 and the second slit 56 can also be provided on the second end face of the end wall 50B. In this case, the first slit 55 and the second slit 56 open in the same direction as the mounting direction DW of the bearing support member 50. Even so, the same effect as the previous (8) to (14) can be obtained.

[0089] • Alternatively, a first slit 55 can be provided on the first end face of the end wall 50B, and a second slit 56 can be provided on the second end face of the end wall 50B. Alternatively, a first slit 55 can be provided on the second end face of the end wall 50B, and a second slit 56 can be provided on the first end face of the end wall 50B. Even so, the same effect as the previous (8) to (14) can be obtained.

[0090] • As a bearing support component 50, a structure in which the second slit 56 is omitted may also be adopted. The portion where the second slit 56 is provided is filled with synthetic resin. Even so, the same effect as the previous (8) to (10) and (12) to (14) can be obtained.

[0091] ·like Figure 9 As shown, the bearing support member 50 may also have a third slit 59 instead of the first slit 55 and the second slit 56. The recess 57 may also be omitted. The third slit 59 is an annular groove extending circumferentially along the end wall 50B. The third slit 59 is provided, for example, in a form that connects the previous first slit 55 and the second slit 56 radially. The outer diameter of the third slit 59 is set to be the same as the outer diameter of the previous first slit 55. The inner diameter of the third slit 59 is set to be the same as the inner diameter of the previous second slit 56. The depth and width of the third slit 59 are adjusted so that the thickness of the resin of the bearing support member 50 is approximately uniform. The third slit 59 constitutes a deformation-allowing part that allows radial elastic deformation of the bearing support member 50. Even so, the same effect as the previous (8) to (13) can be obtained.

[0092] • As a bearing support component 50, a structure in which the rib 58 is omitted may also be adopted. In this case, multiple recesses 57 are connected circumferentially, thereby forming a single annular recess. Even so, the same effect as the previous (8) to (13) can be obtained.

Claims

1. A steering device, wherein, have: A cylindrical support tube with a flange supports the steering shaft so that it can rotate; A speed reducer configured to apply torque to the steering shaft; A housing having a cylindrical portion for housing the reducer, the cylindrical portion being coaxially disposed with the flange; Bolts that connect the flange and the cylindrical portion to each other; A bearing support component that fits into the inner circumferential surface of the cylindrical portion and through which the steering shaft passes; and A bearing, which is located between the outer circumferential surface of the steering shaft and the inner circumferential surface of the bearing support component. The bearing support member has a radially extending wall portion and a deformation-allowing portion configured to allow elastic deformation of the bearing support member in the radial direction. The deformation-allowing portion includes a first slit disposed in the wall portion. The first slit is an annular groove that extends continuously in the circumferential direction along the outer peripheral surface of the bearing support component. The deformation-allowing portion further includes a second slit disposed in the wall portion. The second slit is an annular groove located radially inward relative to the first slit and extending continuously in the circumferential direction along the inner circumferential surface of the bearing support member.

2. The steering device according to claim 1, wherein, The bearing support component has a peripheral wall, the wall portion being an end wall extending radially inward from the axial end of the peripheral wall. The end wall has a first end face and a second end face located on opposite sides of each other in the axial direction. The first slit and the second slit are disposed on the same end face of the first end face and the second end face, or on different end faces of the first end face and the second end face.

3. The steering device according to claim 2, wherein, The first end face has the first slit and the second slit. The second end face has: Multiple recesses are circumferentially spaced in the region of the second end face between the first slit and the second slit; and Multiple ribs are portions of the bearing support component located between two adjacent recesses in the circumferential direction.

4. The steering device according to any one of claims 1 to 3, wherein, The bearing support component and the cylindrical portion have engaging portions that engage with each other in the axial direction of the bearing support component.

5. The steering device according to claim 4, wherein, The engaging portion includes: an outer protrusion extending circumferentially along the outer peripheral surface of the bearing support member; and a groove extending circumferentially along the inner peripheral surface of the cylindrical portion. The outer protrusion engages with the groove in the axial direction of the bearing support component.

6. The steering device according to claim 4, wherein, The bearing support member has: a peripheral wall; an end wall extending radially inward from an axial end of the peripheral wall; and a corner portion formed at the intersection of the peripheral wall and the end wall. The engaging portion includes a stepped portion extending circumferentially along the inner circumferential surface of the cylindrical portion, and the corner portion of the bearing support member. The corner portion engages with the stepped portion axially with the bearing support component.

7. The steering device according to any one of claims 1 to 3, wherein, The bearing support component has an inner protrusion extending circumferentially along the inner circumferential surface of the bearing support component. The inner protrusion engages with the bearing in the axial direction of the bearing support component.

8. The steering device according to any one of claims 1 to 3, wherein, The linear expansion coefficients of the bearing support component and the housing are different.

9. The steering device according to any one of claims 1 to 3, wherein, The reducer has a worm gear that rotates integrally with the steering shaft and a worm that meshes with the worm gear. The housing has a worm gear housing component for housing the worm gear and a worm gear housing component for housing the worm. The cylindrical portion is the worm gear housing component.

Images