Torque limiter and steering device

Abstract

To provide a torque limiter and a steering device capable of suppressing variations in sliding torque.SOLUTION: A steering device includes an intermediate shaft 22, an annular key ring 51, an annular tolerance ring 53, an annular intermediate member 52, and a positioning structure T. The intermediate member 52 includes a coaxial part 81 for keeping the concentricity of a rotation shaft of the intermediate member 52 with respect to a rotation shaft of the intermediate shaft 22 in an acceptable range, and a torque transmission part 82 for transmitting the torque accompanying the rotation of the intermediate shaft 22 to the intermediate member 52. In the state that the coaxial part 81 and the torque transmission part 82 are juxtaposed in an axial direction, the coaxial part 81 is a member fitted on the outer periphery of the intermediate shaft 22, and the torque transmission part 82 is a member loosely fitted on the outer periphery of the intermediate shaft 22. The positioning structure T positions the intermediate member 52 with respect to an axial direction of the intermediate shaft 22 at the two ends in the axial direction of the intermediate member 52.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a torque limiter and a steering device. [Background technology]

[0002] For example, as described in Patent Document 1, a steering device for a vehicle is provided with a steering lock mechanism. From the viewpoint of theft prevention, the steering lock mechanism restricts the rotation of the steering shaft when an activation switch such as an ignition switch is turned off. In the steering device of Patent Document 1, a key ring constituting the steering lock mechanism is press-fitted onto the outer periphery of a fitting portion of the intermediate shaft via a tolerance ring. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-105653 Summary of the Invention [Problem to be solved by the invention]

[0004] The tolerance ring in Patent Document 1 allows rotation of the steering shaft even when the steering is locked. Therefore, it is important to suppress fluctuations in slip torque, which is the criterion for whether the tolerance ring will allow rotation of the steering shaft. This issue is not limited to steering devices; it can similarly arise in any device that includes a torque limiter that uses a tolerance ring to restrict relative rotation between a first rotating member and a second rotating member. [Means for solving the problem]

[0005] A torque limiter that can solve the above problem includes a first rotating member, an annular second rotating member arranged on the outer periphery of the first rotating member, an annular tolerance ring arranged between the first rotating member and the second rotating member and having a spring portion that is elastically deformable in the radial direction, an annular intermediate member arranged between the first rotating member and the tolerance ring, and a positioning structure for positioning the intermediate member with respect to the axial direction of the first rotating member, wherein the intermediate member has a coaxial portion that keeps the concentricity of the rotation axis of the intermediate member with respect to the rotation axis of the first rotating member within an allowable range, and a torque transmission portion that transmits torque associated with rotation of the first rotating member to the intermediate member, wherein the coaxial portion and the torque transmission portion are arranged side by side in the axial direction, the coaxial portion is a portion that is fitted onto the outer periphery of the first rotating member, and the torque transmission portion is a portion that is loosely fitted onto the outer periphery of the first rotating member, and the positioning structure is configured to position the intermediate member with respect to the axial direction of the first rotating member at both axial ends of the intermediate member.

[0006] According to the above configuration, the intermediate member is coupled to the first rotating member so as to rotate integrally with the first rotating member by the torque transmission portion. The coaxial portion reduces the variation in the inter-rotational rattle between the intermediate member and the first rotating member. Furthermore, the coaxial portion and the torque transmission portion allow the intermediate member to be fitted and loosely fitted to the outer periphery of the first rotating member. The fitted and loosely fitted portions can absorb any change in the outer diameter of the first rotating member. This is because, for example, the loosely fitted portion is not rigidly fixed to the first rotating member. In contrast, the positioning structure further positions the intermediate member relative to the axial direction of the first rotating member. In other words, even if the loosely fitted portion is not rigidly fixed to the first rotating member, for example, the intermediate member is less likely to slip off the first rotating member. This reduces the variation in the deformation amount of the spring portion of the tolerance ring. This reduces the variation in the slip torque, which is the criterion for determining whether the tolerance ring will allow the first rotating member to rotate.

[0007] In the torque limiter, the positioning structure may be configured to apply a load for limiting axial movement of the intermediate member from the axial direction of the intermediate member.

[0008] According to the above configuration, the positioning structure can preferably position the first rotating member in the axial direction through the preload on the intermediate member. For example, by adjusting the preload, it is possible to allow the intermediate member to move in the axial direction of the first rotating member. Such movement of the intermediate member can suppress vibrations transmitted from the outside. In other words, the positioning structure constitutes a buffer structure for suppressing vibrations transmitted from the outside.

[0009] In the torque limiter, the positioning structure may include a first component disposed adjacent to the coaxial portion and a second component disposed adjacent to the torque transmission portion, at both axial ends of the intermediate member.

[0010] According to the above configuration, it is possible to diversify the configuration for realizing the positioning structure, which is effective in increasing the versatility of the positioning structure. Specifically, at least one of the first component and the second component may be configured to apply a load to the intermediate member from the axial direction to limit axial movement of the intermediate member.

[0011] In the above torque limiter, an insertion portion into which a lock bar can be inserted from the outside is provided on the outer periphery of the second rotating member, and the second rotating member is configured so that rotation is restricted by inserting the lock bar into the insertion portion, and the torque transmission portion may be arranged so as to overlap with the axial range in which the insertion portion is provided.

[0012] With the above configuration, when the lock bar is inserted, the gap caused by loose fit in the torque transmission portion is filled, thereby making it possible to preferably suppress variation in the amount of deformation of the spring portion of the tolerance ring when the lock bar is inserted.

[0013] A steering device that can solve the above problem includes a steering shaft, an annular key ring arranged on the outer periphery of the steering shaft, an annular tolerance ring arranged between the steering shaft and the key ring and having a spring portion that is elastically deformable in the radial direction, an annular intermediate member arranged between the steering shaft and the tolerance ring, and a positioning structure for positioning the intermediate member with respect to the axial direction of the steering shaft, wherein the intermediate member has a coaxial portion that keeps the concentricity of the rotation axis of the intermediate member with respect to the rotation axis of the steering shaft within an allowable range, and a torque transmission portion that transmits torque associated with rotation of the steering shaft to the intermediate member, wherein the coaxial portion and the torque transmission portion are arranged side by side in the axial direction, the coaxial portion is a portion that is fitted onto the outer periphery of the steering shaft and the torque transmission portion is a portion that is loosely fitted onto the outer periphery of the steering shaft, and the positioning structure is configured to position the intermediate member with respect to the axial direction of the steering shaft at both axial ends of the intermediate member.

[0014] With the above configuration, the amount of deformation of the spring portion of the tolerance ring is less likely to vary, thereby realizing a steering device that can suppress fluctuations in the slip torque that determines whether the tolerance ring will allow rotation of the steering shaft. [Effects of the Invention]

[0015] According to the present invention, fluctuations in slip torque can be suppressed. [Brief explanation of the drawings]

[0016] [Figure 1]1 is a cross-sectional view taken along the axial direction of a steering device of a first embodiment. [Figure 2] FIG. 4 is an enlarged cross-sectional view taken along the axial direction of a fitting portion of a key ring in the column shaft of the first embodiment. [Figure 3] 3 is a cross section perpendicular to the axial direction of the fitting portion of the key ring in the column shaft of the first embodiment, and is an end view taken along line III-III in FIG. 2. [Figure 4] 3 is a cross-sectional view showing the meshing structure of the torque transmission portion of the intermediate member of FIG. 2. [Figure 5] FIG. 3 is a front view showing the fastener of FIG. 2. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. [Figure 7] FIG. 10 is a diagram showing a positioning structure according to a second embodiment. [Figure 8] FIG. 10 is a diagram showing a positioning structure according to a third embodiment. [Figure 9] FIG. 10 is a diagram showing a positioning structure according to a fourth embodiment. [Figure 10] FIG. 10 is a diagram showing a positioning structure according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] First Embodiment A torque limiter and a steering device according to a first embodiment will be described. As used herein, "annular" refers to a shape that can be considered as an entire ring, and includes shapes formed by combining multiple parts or portions to form an annular shape, as well as shapes with a notch or other feature, such as a C-shape. "Annular" shapes include, but are not limited to, circular, elliptical, and polygonal shapes with sharp or rounded corners when viewed in the axial direction. "Cylindrical" refers to a shape that can be considered as an entire ring, and includes shapes formed by combining multiple parts or portions to form an annular shape, as well as shapes with a notch or other feature, such as a C-shape. "Cylindrical" shapes include, but are not limited to, circular, elliptical, and polygonal shapes with sharp or rounded corners when viewed in the axial direction. "Rod-shaped" refers to a shape that can be considered as an entire rod, and includes shapes formed by combining multiple parts or portions to form an annular shape, as well as shapes with a notch or other feature, such as a C-shape. "Rod-shaped" shapes include, but are not limited to, circular, elliptical, and polygonal shapes with sharp or rounded corners when viewed in the axial direction.

[0018] <Overall structure> As shown in FIG. 1, the steering device 1 includes a column shaft 3 that constitutes a steering shaft 2, and a steering column 4 that rotatably houses the column shaft 3. The steering device 1 also includes an electric actuator 5 that applies an assist force to assist the driver in steering. The steering column 4 is mounted on the vehicle so as to extend generally along the longitudinal direction of the vehicle. In the following description, the left side in FIG. 1 is the front side of the vehicle, and the right side in FIG. 1 is the rear side of the vehicle. Furthermore, directions expressed by terms such as "front," "rear," "up," "down," "left," and "right" are defined relative to the vehicle.

[0019] A steering wheel 6 is connected to the rear end of the column shaft 3. For example, an intermediate shaft and a pinion shaft that constitute the steering shaft 2 are connected to the front end of the column shaft 3. The pinion shaft is connected to the steered wheels via a rack shaft. This causes the steered wheels to turn in response to the driver's steering operation. The steering device 1 is, for example, a steering device in which the rotation of the steering wheel 6 is mechanically transmitted to a steering section that steers the steered wheels. Although a detailed description will be omitted, the steering device 1 is equipped with a tilt adjustment function that adjusts the height position of the steering wheel 6 and a telescopic adjustment function that adjusts its fore-aft position.

[0020] The electric actuator 5 includes a motor 11 as a drive source and a speed reduction mechanism 12 that reduces the rotation speed of the motor 11. The speed reduction mechanism 12 is, for example, a worm reducer. The electric actuator 5 applies an assist force by reducing the rotation speed of the motor 11 and transmitting it to the column shaft 3.

[0021] More specifically, the column shaft 3 includes an upper shaft 21, an intermediate shaft 22 which is a first rotating member, a torsion bar 23, and a lower shaft 24. The upper shaft 21 has a long cylindrical shape. The upper shaft 21 has, for example, a circular shape when viewed in the axial direction. The steering wheel 6 is connected to the rear end of the upper shaft 21. The intermediate shaft 22 has a long rod shape. The intermediate shaft 22 has, for example, a circular shape when viewed in the axial direction. The upper shaft 21 is spline-fitted to the intermediate shaft 22. As a result, the upper shaft 21 is connected to the intermediate shaft 22 so as to be rotatable integrally with the intermediate shaft 22 and movable relative to the intermediate shaft 22 in the axial direction. A fitting portion 25 is provided at the front end of the intermediate shaft 22. The fitting portion 25 has a fitting hole 26 that opens to the front side of the vehicle. A key ring 51, which is a second rotating member, is fitted onto the outer periphery of the fitting portion 25 of the intermediate shaft 22 via an intermediate member 52 and a tolerance ring 53, as will be described later.

[0022] The torsion bar 23 has a long rod shape. The torsion bar 23 has, for example, a circular shape when viewed in the axial direction. The lower shaft 24 has a long cylindrical shape. The lower shaft 24 has, for example, a circular shape when viewed in the axial direction. The rear end of the torsion bar 23 is press-fitted into a fitting hole 26, thereby being coupled to the intermediate shaft 22 so as to be rotatable together with the intermediate shaft 22. The front end of the torsion bar 23 is press-fitted into an opening at the front end of the lower shaft 24, thereby being coupled to the lower shaft 24 so as to be rotatable together with the intermediate shaft 22 via the torsion bar 23. The torsion bar 23 is coupled to the intermediate shaft 22 and the lower shaft 24 so as to be rotatable together with them, for example, by being serrated-fitted to the intermediate shaft 22 and the lower shaft 24.

[0023] A worm wheel 27 constituting the speed reduction mechanism 12 is connected to the lower shaft 24 so as to be rotatable together with the motor 11. The motor 11 is connected to the worm wheel 27 via the worm shaft constituting the speed reduction mechanism 12. As a result, the rotation of the motor 11 is reduced in speed by the speed reduction mechanism 12 and transmitted to the lower shaft 24, thereby providing an assist force.

[0024] The steering column 4 includes a cylindrical inner tube 31 that rotatably accommodates the upper shaft 21, an outer tube 32, and a housing 33. The inner tube 31 and the outer tube 32 have, for example, a circular shape when viewed in the axial direction. The inner tube 31 rotatably supports the upper shaft 21 via a bearing 34. The inner tube 31 and the outer tube 32 are normally fitted together in a state in which relative movement in the axial direction is restricted. As a result, the inner tube 31 and the outer tube 32 move together as a unit even during so-called telescopic movement, but are configured to move relative to each other in the axial direction and contract when an impact load is applied due to a vehicle collision or the like.

[0025] The housing 33 constitutes the electric actuator 5. The housing 33 accommodates a sensor unit 41 that detects steering torque based on the amount of torsion of the torsion bar 23, the reduction mechanism 12, etc. The housing 33 rotatably supports the intermediate shaft 22 via a bearing 42, and rotatably supports the lower shaft 24 via bearings 43 and 44.

[0026] <Key ring fitting structure> Next, we will explain the fitting structure of the key ring 51 that constitutes the steering lock mechanism S. The steering lock mechanism S is configured to restrict rotation of the column shaft 3 when the vehicle start switch is off. The vehicle start switch is, for example, an ignition switch or a start switch.

[0027] 2 and 3, the steering lock mechanism S includes a key ring 51 fitted onto the outer periphery of the intermediate shaft 22, and a lock bar B provided on the vehicle body. An intermediate member 52 is connected to the outer periphery of the fitting portion 25 of the intermediate shaft 22 so as to be rotatable together with the key ring 51. The key ring 51 is fitted onto the outer periphery of the intermediate member 52 via a tolerance ring 53. The steering lock mechanism S restricts the rotation of the column shaft 3 in accordance with the frictional force generated between the tolerance ring 53 and the key ring 51 and intermediate member 52 by restraining the rotation of the key ring 51 with the lock bar B. In other words, the key ring 51, the intermediate member 52, and the tolerance ring 53 form a torque limiter.

[0028] 1 and 2, the fitting portion 25 has a flange portion 61, a shaft portion 62, a meshing portion 63, and a fixing portion 64. The flange portion 61, the shaft portion 62, the meshing portion 63, and the fixing portion 64 are arranged side by side from the front to the rear in the axial direction. In the fitting portion 25, the flange portion 61 is adjacent to the rear side of the portion where the bearing 42 is provided. The shaft portion 62 is adjacent to the rear side of the portion where the flange portion 61 is provided. The meshing portion 63 is adjacent to the rear side of the portion where the shaft portion 62 is provided, with a small gap therebetween. The fixing portion 64 is adjacent to the rear side of the portion where the meshing portion 63 is provided.

[0029] The flange portion 61 has an annular shape extending radially outward. The flange portion 61 has, for example, a circular shape when viewed in the axial direction. The shaft portion 62 has a cylindrical shape extending in the axial direction. The outer peripheral surface of the shaft portion 62 has, for example, a smooth cylindrical shape. The outer diameter of the shaft portion 62 is smaller than the outer diameter of the flange portion 61. In other words, a boundary portion 61a between the flange portion 61 and the shaft portion 62 has a stepped shape. The meshing portion 63 has a plurality of internal serrations 63a. The internal serrations 63a protrude radially inward and extend axially. The outer diameter of the tooth tips of the internal serrations 63a is approximately the same as the outer diameter of the shaft portion 62. The fixing portion 64 has an annular groove. The fixing portion 64 is, for example, formed continuously over the entire circumferential direction.

[0030] As shown in FIGS. 2 and 3 , the key ring 51 is annular. For example, the key ring 51 has a circular shape when viewed in the axial direction. The outer periphery of the key ring 51 is provided with a plurality of insertion portions 71 into which the lock bar B can be inserted. The insertion portions 71 are groove-shaped and extend in the axial direction from the end on the side where the bearing 42 is provided. For example, the plurality of insertion portions 71 are arranged at equal angular intervals on the outer periphery of the key ring 51. The inner periphery of the key ring 51 is provided with an accommodating recess 72 into which the tolerance ring 53 can be accommodated. The accommodating recess 72 is formed between the inner circumferential surface of the key ring 51 and the outer circumferential surface of the intermediate member 52. For example, the accommodating recess 72 is formed continuously over the entire circumferential direction.

[0031] The tolerance ring 53 is annular. For example, the tolerance ring 53 has a C-shape when viewed in the axial direction. The tolerance ring 53 is formed, for example, by bending a plate of spring steel into a C-shape. The tolerance ring 53 is provided with a plurality of spring portions 53a that are elastically deformable in the radial direction. Each spring portion 53a has a generally rectangular shape that bulges outward in the radial direction. For example, the multiple spring portions 53a are formed at equal angular intervals around the circumferential direction of the tolerance ring 53 and in two rows spaced apart in the axial direction. The tolerance ring 53 is accommodated in the accommodation recess 72 of the key ring 51.

[0032] The intermediate member 52 has an annular shape. For example, the intermediate member 52 has a circular shape when viewed in the axial direction. The outer diameter of the intermediate member 52 is set to a predetermined outer diameter corresponding to the inner diameter of the tolerance ring 53 over the entire axial length of the intermediate member 52. The predetermined outer diameter is an outer diameter at which the spring portion 53a, which is compressed radially between the key ring 51 and the intermediate member 52, is compressed by a predetermined amount. The predetermined compression amount is a compression amount that generates a normal force in the spring portion 53a such that the sliding torque corresponding to the friction force generated between the tolerance ring 53 and the intermediate member 52 becomes a predetermined torque. The predetermined outer diameter and the predetermined compression amount are set in advance based on the results of experiments, etc.

[0033] 2, the intermediate member 52 has a coaxial portion 81 and a torque transmission portion 82. The coaxial portion 81 and the torque transmission portion 82 are arranged side by side from the front side to the rear side in the axial direction. The coaxial portion 81 is provided on the front side of the intermediate member 52, where the bearing 42 is provided. The torque transmission portion 82 is adjacent to the rear side of the portion where the coaxial portion 81 is provided, with a small gap between them. The torque transmission portion 82 is provided on the rear side of the intermediate member 52, opposite the side where the bearing 42 is provided.

[0034] The coaxial portion 81 has a cylindrical shape extending in the axial direction. The inner peripheral surface of the coaxial portion 81 has, for example, a smooth cylindrical shape. The inner peripheral surface of the coaxial portion 81 can come into contact with the outer peripheral surface of the shaft portion 62 in the radial direction. The planar accuracy of the inner peripheral surface of the coaxial portion 81 and the outer peripheral surface of the shaft portion 62 is ensured to a degree that the coaxiality of the rotation axis of the intermediate member 52 with respect to the rotation axis of the intermediate shaft 22 can be within an allowable range. The inner diameter of the coaxial portion 81 is smaller than the outer diameter of the shaft portion 62. The axial length of the coaxial portion 81 is approximately the same as the axial length of the shaft portion 62. The torque transmission portion 82 has a plurality of external serrations 82a. The external serrations 82a protrude radially outward and extend in the axial direction. The axial length of the external serrations 82a is approximately the same as the axial length of the internal serrations 63a.

[0035] 4, the tooth groove width of the internal serrations 63a is larger than the tooth thickness of the external serrations 82a. As a result, in the torque transmission portion 82, a circumferential gap is formed between the internal serrations 63a and the external serrations 82a when the intermediate member 52 is fitted into the fitting portion 25 so as to be rotatable together with the intermediate member 52. The circumferential gap is secured within a range that allows torque accompanying rotation of the intermediate shaft 22 to be transmitted to the intermediate member 52.

[0036] As shown in FIG. 2 , the intermediate member 52 is, for example, axially inserted onto the meshing portion 63, which is the rear side of the fitting portion 25. The intermediate member 52 is axially inserted onto the meshing portion 63 from the coaxial portion 81 side, which is the front side. When the coaxial portion 81 and the axial portion 62 are overlapping in the axial direction, the inner circumferential surface of the coaxial portion 81 and the outer circumferential surface of the axial portion 62 face each other. As a result, the coaxial portion 81 is loosely fitted onto the axial portion 62. When the torque transmission portion 82 and the meshing portion 63 are overlapping in the axial direction, the external serrations 82 a of the torque transmission portion 82 and the internal serrations 63 a of the meshing portion 63 are engaged with each other. As a result, the torque transmission portion 82 is loosely fitted into the meshing portion 63.

[0037] The coaxial portion 81 of the intermediate member 52 is loosely fitted onto the shaft portion 62, so that the coaxiality of the rotation axis of the intermediate shaft 22 is within an allowable range. Furthermore, the torque transmission portion 82 of the intermediate member 52 is loosely fitted into the meshing portion 63, so that torque accompanying the rotation of the intermediate shaft 22 is transmitted thereto. However, the loose fit between the coaxial portion 81 and the shaft portion 62 and the loose fit between the torque transmission portion 82 and the meshing portion 63 do not contribute to positioning the intermediate member 52 with respect to the axial direction of the intermediate shaft 22.

[0038] <Intermediate member positioning structure> Next, a description will be given of the positioning structure T. The positioning structure T is configured to position the intermediate member 52 with respect to the axial direction of the intermediate shaft 22.

[0039] As shown in FIG. 2 , the positioning structure T includes a first component Ta and a second component Tb. The first component Ta includes, for example, a boundary portion 61a of the flange portion 61. The boundary portion 61a abuts against an end face 52a of the intermediate member 52 on the coaxial portion 81 side in the axial direction. That is, the boundary portion 61a is disposed adjacent to the coaxial portion 81 of the intermediate member 52. The second component Tb includes, for example, a fixing portion 64 of the fitting portion 25 and a stopper 90 fitted into the fixing portion 64. The stopper 90 abuts against an end face 52b of the intermediate member 52 on the torque transmission portion 82 side in the axial direction. That is, the stopper 90 is disposed adjacent to the torque transmission portion 82 of the intermediate member 52.

[0040] More specifically, as shown in FIGS. 2, 5, and 6, the stopper 90 has a C-shape. The stopper 90 is, for example, an arch-shaped retaining ring and has an arch-shaped shape when viewed in the radial direction. The curvature of the arch determines the spring constant and is secured within a range that allows axial movement of the intermediate member 52 relative to the intermediate shaft 22 and absorbs desired vibrations. In other words, the positioning structure T also functions as a buffer structure. The stopper 90 includes an annular portion 91 having a fitting opening 90a. The annular portion 91 is formed with a plurality of claws 92, 93 that protrude toward the inner periphery. The claws 92 are formed at both ends that form the fitting opening 90a. The annular portion 91 is formed with claws 93 at positions circumferentially spaced at equal angular intervals from the two claws 92. A diameter R1 of an imaginary circle M1 that includes the tips of the two claws 92 and the claws 93 is smaller than a diameter R2 of the groove bottom of the fixing portion 64.

[0041] As shown in FIG. 2 , the stopper 90 is fitted into the fixed portion 64 from the radial direction, for example. The stopper 90 is fitted through a fitting opening 90a through overall elastic deformation. When the stopper 90 is fitted into the fixed portion 64, the claws 92 and 93 abut against the fixed portion 64 in the axial direction, and the annular portion 91 abuts against the end face 52b of the intermediate member 52 on the torque transmission portion 82 side in the axial direction. In the axial direction of the stopper 90, the side where the claws 92 and 93 abut against the fixed portion 64 is different from the side where the annular portion 91 abuts against the torque transmission portion 82. Because the stopper 90 is in a state where the curvature of the arch is reduced between the fixed portion 64 and the end face 52a on the coaxial portion 81 side, the claws 92 and 93 press the fixed portion 64 rearward, while the annular portion 91 presses the end face 52b forward. The intermediate member 52 has its end surface 52a on the coaxial portion 81 side abutting against the boundary portion 61a, thereby restricting its axial movement toward the front. As a result, the stopper 90 is configured to apply a load to the intermediate member 52 from the axial direction to restrict the axial movement of the intermediate member 52 toward the rear.

[0042] By accommodating the tolerance ring 53 in the accommodating recess 72, the key ring 51 is fitted onto the outer periphery of the intermediate member 52 via the tolerance ring 53. In this way, a key ring unit is assembled from the key ring 51, the tolerance ring 53, and the intermediate member 52. The key ring unit assembled in this manner, i.e., the intermediate member 52, is fitted into the fitting portion 25 of the intermediate shaft 22. Thereafter, the intermediate member 52 is further positioned with respect to the axial direction of the intermediate shaft 22 by the boundary portion 61a, the fixing portion 64, and the stopper 90, thereby being attached to the intermediate shaft 22.

[0043] As shown in FIG. 2 , the steering shaft 2 has a cylindrical portion 101 formed by a clearance fit between the coaxial portion 81 and the shaft portion 62, and a serration portion 102 formed by a loose fit between the torque transmission portion 82 and the meshing portion 63. The axial range L1 in which the cylindrical portion 101 is formed is greater than the axial range L2 in which the serration portion 102 is formed. The axial range L2 is, for example, less than half of the range in which the shaft portion 62 and the meshing portion 63, i.e., the coaxial portion 81 and the torque transmission portion 82, are provided. The axial range L2 is arranged so as to overlap with the axial range in which the insertion portion 71 of the key ring 51 is provided. In other words, the meshing portion 63, i.e., the torque transmission portion 82, is arranged so as to be included in the axial range in which the insertion portion 71 of the key ring 51 is provided.

[0044] <Operation of this embodiment> The torque transmission portion 82 couples the intermediate member 52 to the intermediate shaft 22 so that the intermediate member 52 can rotate integrally with the intermediate shaft 22. The coaxial portion 81 reduces variations in the play of the integral rotation between the intermediate member 52 and the intermediate shaft 22. The coaxial portion 81 and the torque transmission portion 82 allow the intermediate member 52 to be fitted and loosely fitted onto the outer periphery of the intermediate shaft 22. The fitted and loosely fitted portions, i.e., the cylindrical portion 101 and the serration portion 102, can absorb any changes in the outer diameter of the intermediate shaft 22. This is because, for example, the serration portion 102 is not rigidly fixed to the intermediate shaft 22. In contrast, the positioning structure T further positions the intermediate member 52 with respect to the axial direction of the intermediate shaft 22. In other words, even if the serration portion 102 is not rigidly fixed to the intermediate shaft 22, the intermediate member 52 is prevented from falling off the intermediate shaft 22. This makes it difficult for the deformation amount of the spring portion 53a of the tolerance ring 53 to vary.

[0045] <Effects of this embodiment> (1-1) The functions of the coaxial portion 81, the torque transmission portion 82, and the positioning structure T make it difficult for the deformation amount of the spring portion 53a of the tolerance ring 53 to vary. Therefore, it is possible to suppress fluctuations in the sliding torque, which is the criterion for determining whether the tolerance ring 53 will allow the intermediate shaft 22 to rotate.

[0046] (1-2) In the positioning structure T, the stopper 90 is configured to apply a load to the intermediate member 52 in the axial direction to limit axial movement of the intermediate member 52. As a result, the positioning structure T can preferably position the intermediate shaft 22 in the axial direction through preload on the intermediate member 52. The load applied to the intermediate member 52 is adjusted, for example, to allow axial movement of the intermediate member 52 relative to the intermediate shaft 22. Such movement of the intermediate member 52 can suppress vibrations transmitted from the outside. In other words, the positioning structure T constitutes a buffer structure for suppressing vibrations transmitted from the outside.

[0047] (1-3) The positioning structure T includes a first component Ta arranged adjacent to the coaxial portion 81 and a second component Tb arranged adjacent to the torque transmission portion 82 at both axial ends of the intermediate member 52.

[0048] Specifically, in the first embodiment, the stopper 90 included in the second component Tb of the first component Ta and the second component Tb is configured to apply a load to the intermediate member 52 in the axial direction to limit the axial movement of the intermediate member 52.

[0049] This allows for diversification of the configuration for realizing the positioning structure T. This is effective in increasing the versatility of the positioning structure. (1-4) In the intermediate member 52, the coaxial portion 81 and the torque transmission portion 82 are arranged side by side in the axial direction. This prevents the intermediate member 52 from being inserted midway into the meshing portion 63 even if an attempt is made to insert the intermediate member 52 from the torque transmission portion 82 side, which is the rear side. This is effective in reducing incorrect assembly of the intermediate member 52 and, ultimately, in improving the efficiency of the assembly work.

[0050] (1-5) The torque transmission portion 82 is arranged to overlap the axial range in which the insertion portion 71 of the key ring 51 is provided. This fills any gaps caused by loose fit in the torque transmission portion 82 when the lock bar B is inserted. This effectively reduces variations in the amount of deformation of the spring portion 53a of the tolerance ring 53 when the lock bar B is inserted.

[0051] (1-6) By adopting the torque limiter of the first embodiment, it is possible to realize a steering device 1 that can suppress fluctuations in the slip torque, which is the criterion for determining whether the tolerance ring 53 will allow the steering shaft 2 to rotate.

[0052] (1-7) The stopper 90 has a C-shape with an insertion opening 90a. The stopper 90 can be inserted into the fixing portion 64 from the radial direction. This makes it easy to attach the stopper 90.

[0053] Second Embodiment The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. For ease of explanation, the same components as those in the first embodiment will be assigned the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

[0054] As shown in FIG. 7, the positioning structure T of this embodiment is configured such that the second component Tb includes stoppers 110 and 120 instead of the fixing portion 64 and the stopper 90. The stopper 110 is annular. The stopper 110 is, for example, a push nut. The stopper 110 can be fixed to the fitting portion 25 even if the fitting portion 25 is not grooved. In other words, the fitting portion 25 of this embodiment does not have a fixing portion 64 for fixing the stopper 110, i.e., a groove. The stopper 110 has an annular portion 111. The annular portion 111 is formed with a plurality of claw portions 112 that protrude toward the inner periphery. The claw portions 112 are elastically deformable and have a spring constant within a range that allows axial movement of the intermediate member 52 relative to the intermediate shaft 22 and can absorb desired vibrations.

[0055] The stopper 110 is fitted into the fitting portion 25 in the axial direction. The stopper 110 is externally fitted onto the fitting portion 25 through elastic deformation of the claw portions 112. When the stopper 110 is fitted into the fitting portion 25, the annular portion 111 abuts against the end face 52b of the intermediate member 52 on the torque transmission portion 82 side in the axial direction via the stopper 120. The stopper 120 is annular. The stopper 120 is, for example, a wave washer. That is, the stopper 120 fills the gap between the annular portion 111 and the end face 52b of the stopper 110 fitted into the fitting portion 25. When the claw portions 112 of the stopper 110 are in an elastically deformed state, the claw portions 112 press the fitting portion 25 rearward, while the annular portion 111 presses the end face 52b forward. As a result, the stopper 110 is configured to apply a load to the intermediate member 52 in the axial direction to limit the axial movement of the intermediate member 52 toward the rear side.

[0056] <Effects of this embodiment> According to the second embodiment described above, the same actions and effects as those (1-1) to (1-6) of the first embodiment can be obtained. Furthermore, according to this embodiment, the following effects can be further obtained.

[0057] (2-1) The stopper 110 is, for example, a push nut. This eliminates the need to machine a groove in the fitting portion 25. This is effective in simplifying the manufacturing of the fitting portion 25, i.e., the intermediate shaft 22, and ultimately reducing costs.

[0058] Third Embodiment The third embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. For ease of explanation, the same components as those in the first embodiment will be assigned the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

[0059] As shown in FIG. 8, the positioning structure T of this embodiment is configured so that the second component Tb includes a fixing portion 65 and fasteners 130 and 140 instead of the fixing portion 64 and fastener 90.

[0060] The stopper 130 is annular. The stopper 130 is, for example, a disc spring. The stopper 130 is elastically deformable and has a spring constant within a range that allows axial movement of the intermediate member 52 relative to the intermediate shaft 22 and can absorb desired vibrations. The stopper 130 is fixed to the fitting portion 25 by a stopper 140 that is fitted into a fixing portion 65 of the fitting portion 25. The fixing portion 65 has an annular groove. The fixing portion 65 is, for example, formed continuously over the entire circumferential direction. The stopper 140 is annular. The stopper 140 is, for example, a snap ring. The stopper 140 has an inner circumferential side fitted into the fixing portion 65, and an outer circumferential side fixes the stopper 130.

[0061] The stopper 130 is fitted onto the fitting portion 25 in the axial direction. When the stopper 130 is fitted onto the fitting portion 25, the outer circumferential side thereof abuts against the end face 52b of the intermediate member 52 on the torque transmission portion 82 side in the axial direction. The stopper 130 is elastically deformed to fill the gap between the outer circumferential side of the stopper 140 fitted into the fixing portion 65 and the end face 52b. When the stopper 130 is in an elastically deformed state, the inner circumferential side thereof presses the stopper 140 rearward, while the outer circumferential side thereof presses the end face 52b forward. As a result, the stopper 130 is configured to apply a load to the intermediate member 52 in the axial direction to limit axial movement of the intermediate member 52 rearward.

[0062] <Effects of this embodiment> According to the third embodiment described above, the same actions and effects as those (1-1) to (1-6) of the first embodiment can be obtained. Furthermore, according to this embodiment, the following effects can be further obtained.

[0063] (3-1) The stopper 130 is, for example, a disc spring. This not only makes it easy to assemble the stopper 130 but also makes it easy to set the spring constant. This is effective in simplifying the manufacture of the torque limiter.

[0064] <Fourth embodiment> The fourth embodiment will be described below with reference to the drawings, focusing on the differences from the third embodiment. For ease of explanation, the same components as those in the third embodiment will be assigned the same reference numerals as those in the third embodiment, and the description thereof will be omitted.

[0065] As shown in FIG. 9, the positioning structure T of this embodiment is configured such that the first component Ta includes a stopper 130 in addition to the boundary portion 61a, and the second component Tb includes a fixing portion 65 and a stopper 140.

[0066] More specifically, the stopper 130 is fitted into the boundary portion 61a of the fitting portion 25. With the stopper 130 fitted into the boundary portion 61a, the inner circumferential side abuts against the boundary portion 61a in the axial direction, and the outer circumferential side abuts against the end face 52a of the intermediate member 52 on the coaxial portion 81 side in the axial direction. Because the stopper 130 is in an elastically deformed state, the inner circumferential side presses the boundary portion 61a forward, while the outer circumferential side presses the end face 52a rearward. The end face 52b of the intermediate member 52 on the torque transmission portion 82 side abuts against the stopper 140, thereby restricting rearward axial movement of the intermediate member 52. As a result, the stopper 130 is configured to apply a load to the intermediate member 52 in the axial direction to restrict forward axial movement of the intermediate member 52.

[0067] According to the fourth embodiment described above, the actions and effects similar to those of (1-1) to (1-6) of the first embodiment and (3-1) of the third embodiment can be obtained. Fifth Embodiment The fifth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. For ease of explanation, the same components as those in the first embodiment will be assigned the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

[0068] 10 , the positioning structure T of this embodiment is configured so that the second component Tb includes a crimping portion 66 instead of including the fixing portion 64 and the stopper 90. The internal serrations 63a in the meshing portion 63 of this embodiment extend axially further rearward than the rear end of the external serrations 82a in the torque transmission portion 82. In other words, the internal serrations 63a are not meshed with the external serrations 82a and include exposed portions 63b that are not covered by the intermediate member 52.

[0069] The crimped portion 66 is obtained by crimping the exposed portion 63b. The exposed portion 63b is crimped in the radial direction by, for example, a crimping jig J1. Alternatively, the exposed portion 63b may be crimped in the axial direction by, for example, a crimping jig J2. The crimped portion 66 restricts axial movement of the external serrations 82a of the torque transmission portion 82 by crimping the teeth of the exposed portion 63b so as to crush them into an irregular shape. In this way, the crimped portion 66 is configured to rigidly fix the intermediate member 52 in the axial direction of the intermediate shaft 22.

[0070] <Effects of this embodiment> According to the fifth embodiment described above, the same actions and effects as those of (1-1), (1-4) to (1-6) of the first embodiment can be obtained. Furthermore, according to this embodiment, the following effects can be further obtained.

[0071] (5-1) The use of the crimped portion 66 in the second component Tb is effective in rigidly fixing the intermediate member 52 in the axial direction of the intermediate shaft 22. In addition, the use of the crimped portion 66 in the second component Tb is also effective in simplifying the configuration of the torque limiter.

[0072] <Other embodiments> The above-described embodiments may be modified as follows: In addition, the following other embodiments may be combined with each other within the scope of technical compatibility.

[0073] In the first embodiment, the first component Ta may have the same configuration as the second component Tb. That is, the intermediate member 52 may be positioned with respect to the axial direction of the intermediate shaft 22 by the functions of the stoppers 90 and the fixing portion 64 at both axial ends. The other embodiments described herein can be similarly applied to the second, third, and fifth embodiments. For example, in the second embodiment, the intermediate member 52 may be positioned with respect to the axial direction of the intermediate shaft 22 by the functions of the stoppers 110 and 120 at both axial ends.

[0074] In the second embodiment, the fitting portion 25 may be formed with an annular groove for fixing the claw portion 112 of the stopper 110. In the above embodiments, the key ring unit is assembled and then attached to the intermediate shaft 22. However, the key ring unit may be assembled after the intermediate member 52 is attached to the intermediate shaft 22.

[0075] In each of the above-described embodiments, the meshing portion 63, i.e., the torque transmission portion 82, may be disposed so as to overlap at least a portion of the axial range in which the insertion portion 71 of the key ring 51 is provided.

[0076] In each of the above embodiments, the meshing portion 63, i.e., the torque transmission portion 82, may be arranged so as not to overlap the axial range in which the insertion portion 71 of the key ring 51 is provided. In each of the above embodiments, the axial range L1 in which the cylindrical portion 101 is formed may be smaller than the axial range L2 in which the serration portion 102 is formed. That is, the axial range L2 may be, for example, half or more of the range in which the shaft portion 62 and the meshing portion 63, i.e., the coaxial portion 81 and the torque transmission portion 82, are provided. The axial range L1 and the axial range L2 may be continuous with no gap between them.

[0077] In each of the above embodiments, the outer circumferential surface of the shaft portion 62 or the outer circumferential surface of the coaxial portion 81 may be tapered. That is, the cylindrical portion 101 may be fitted by light press-fitting with some interference.

[0078] In each of the above embodiments, the serration portion 102 need only be loosely fitted and capable of transmitting torque accompanying the rotation of the intermediate shaft 22 to the intermediate member 52, and need not necessarily be meshed by serrations. For example, the serration portion 102 may be loosely fitted between a single groove and a single tooth.

[0079] In each of the above embodiments, the meshing portion 63 of the fitting portion 25 may have external serrations instead of the internal serrations 63 a. That is, the torque transmission portion 82 of the intermediate member 52 may have internal serrations instead of the external serrations 82 a.

[0080] In each of the above embodiments, the orientation of the key ring 51 may be reversed. In other words, the orientation of the opening of the storage recess 72 may be reversed. In each of the above embodiments, the arrangement of the first component Ta and the second component Tb may be reversed.

[0081] In each of the above embodiments, the steering device 1 may be a steer-by-wire steering device in which power transmission is separated between a steering unit steered by a driver and a steering unit that steers the steered wheels in response to steering by the driver.

[0082] In each of the above embodiments, a torque limiter may be applied in addition to the steering lock mechanism S of the steering device 1. Next, the technical ideas that can be understood from the above-described embodiments and modifications will be described below.

[0083] (Note) A steering device in which the steering shaft includes a first shaft having a fitting hole opening at one end in the axial direction, and a second shaft press-fitted into the fitting hole, and the intermediate member is disposed on the outer periphery of the fitting portion of the first shaft where the fitting hole is provided. [Explanation of symbols]

[0084] 1...Steering device 2...Steering shaft 22...Intermediate shaft (first rotating member) 51...Key ring (second rotating member) 52...Intermediate member 53...Tolerance ring 62...Shaft 63...Engagement part 64, 65...Fixed part 66... ​​Crimping part 71...insertion part 81…Coaxial part 82...Torque transmission section 90, 110, 120, 130, 140... Fasteners B…Rock Bar T... Positioning structure Ta...first component Tb…Second component

Claims

1. a first rotating member; an annular second rotating member disposed on an outer periphery of the first rotating member; an annular tolerance ring disposed between the first rotary member and the second rotary member and having a spring portion that is elastically deformable in a radial direction; an annular intermediate member disposed between the first rotating member and the tolerance ring; a positioning structure for positioning the intermediate member with respect to the axial direction of the first rotary member, the intermediate member has a coaxial portion for keeping the concentricity of the rotation axis of the intermediate member with respect to the rotation axis of the first rotating member within an allowable range, and a torque transmission portion for transmitting torque associated with rotation of the first rotating member to the intermediate member, the coaxial portion and the torque transmission portion are arranged side by side in the axial direction, the coaxial portion is fitted onto an outer periphery of the first rotating member, and the torque transmission portion is loosely fitted onto the outer periphery of the first rotating member, The positioning structure is configured to position the intermediate member with respect to the axial direction of the first rotating member at both axial ends of the intermediate member.

2. 2. The torque limiter according to claim 1, wherein the positioning structure is configured to apply a load for limiting axial movement of the intermediate member from the axial direction of the intermediate member.

3. The torque limiter according to claim 2 , wherein the positioning structure includes a first component disposed adjacent to the coaxial portion and a second component disposed adjacent to the torque transmission portion at both axial ends of the intermediate member.

4. 4. The torque limiter according to claim 3, wherein at least one of the first component and the second component is configured to apply a load to the intermediate member from the axial direction to limit axial movement of the intermediate member.

5. an insertion portion into which a lock bar can be inserted from the outside is provided on the outer periphery of the second rotating member; The second rotating member is configured such that rotation thereof is restricted by inserting the lock bar into the insertion portion, The torque limiter according to any one of claims 1 to 4, wherein the torque transmission portion is arranged so as to overlap with an axial range in which the insertion portion is provided.

6. A steering shaft; an annular key ring disposed on the outer periphery of the steering shaft; an annular tolerance ring disposed between the steering shaft and the key ring and having a spring portion that is elastically deformable in a radial direction; an annular intermediate member disposed between the steering shaft and the tolerance ring; a positioning structure for positioning the intermediate member with respect to the axial direction of the steering shaft, the intermediate member has a coaxial portion for keeping the concentricity of the rotation axis of the intermediate member with respect to the rotation axis of the steering shaft within an allowable range, and a torque transmission portion for transmitting torque caused by rotation of the steering shaft to the intermediate member, the coaxial portion and the torque transmission portion are arranged side by side in the axial direction, the coaxial portion is fitted onto an outer periphery of the steering shaft, and the torque transmission portion is loosely fitted onto the outer periphery of the steering shaft, The positioning structure is configured to position the intermediate member with respect to the axial direction of the steering shaft at both axial ends of the intermediate member.

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