Torque limiter and steering device

Abstract

To provide a torque limiter which can inhibit variations of slipping torque of each manufactured product, and to provide a steering device.SOLUTION: A steering device includes: an intermediate shaft 22; an annular key ring 51 disposed at an outer periphery of the intermediate shaft 22; an annular tolerance ring 53 disposed between the intermediate shaft 22 and the key ring 51; and an annular intermediate member 52 disposed between the intermediate shaft 22 and the tolerance ring 53. The intermediate member 52 has: a connection part 81 which connects the intermediate member 52 with the intermediate shaft 22 so that these components can rotate integrally; and an extending part 82 extending from the connection part 81 in an axial direction. The connection part 81 is configured to be fitted in an outer periphery of the intermediate shaft 22. The extending part 82 is configured to make a pressure applied to the intermediate shaft 22 smaller than a pressure applied to the connection part 81. The tolerance ring 53 is disposed at an outer periphery of the extending part 82 so as not to overlap with an axial range L1 where the connection part 81 is provided.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, steering devices for vehicles are often 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.

[0003] In the steering device of Patent Document 1, the steering lock mechanism is provided on the outer periphery of the steering shaft. The steering shaft includes an upper shaft to which a steering wheel is connected, an intermediate shaft connected to the upper shaft, and a drive shaft connected to the intermediate shaft and to which the rotation of a motor is transmitted. The drive shaft includes a cylindrical input shaft and an output shaft, and a rod-shaped torsion bar. The input shaft and the output shaft are connected to each other via the torsion bar. The intermediate shaft has a fitting portion provided with a fitting hole that opens at one end in the axial direction. The drive shaft is connected to the intermediate shaft by pressing an end of the input shaft into the fitting hole. The key ring constituting the steering lock mechanism is provided with an insertion portion on its outer periphery into which a lock bar can be inserted. The key ring is fitted to the outer periphery of the fitting portion of the intermediate shaft via a tolerance ring. The tolerance ring is an annular member having a spring portion that is elastically deformable in the radial direction, and generates a friction force corresponding to the compression amount of the spring portion between the tolerance ring, the fitting portion of the intermediate shaft, and the key ring.

[0004] When the lock bar is inserted into the insertion portion of the key ring, rotation of the key ring is restricted. Therefore, when the torque input to the steering shaft is less than the slip torque corresponding to the frictional force of the tolerance ring, rotation of the steering shaft is restricted. On the other hand, when the torque input to the steering shaft is equal to or greater than the slip torque, the steering shaft rotates relative to the tolerance ring, allowing its rotation. This makes it possible to steer even if rotation of the steering shaft is restricted due to, for example, a malfunction of the steering lock mechanism. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-105653 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, the slip torque is determined by the frictional force acting between the tolerance ring and the intermediate shaft, i.e., the amount of compression of the spring portion of the tolerance ring, so it is important to control the dimensions of the fitting portion of the intermediate shaft. Meanwhile, in a configuration such as that described in Patent Document 1, the outer diameter of the fitting portion may change slightly when the end of the input shaft is press-fitted. As a result, the amount of compression of the spring portion may vary, and the slip torque based on the frictional force corresponding to the amount of compression may vary for each individual manufactured product.

[0007] The above-described problem is not limited to steering devices, but may occur 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]

[0008] A torque limiter that solves the above problem comprises a first rotating member, a ring-shaped second rotating member arranged on the outer periphery of the first rotating member, a ring-shaped 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, and a ring-shaped intermediate member arranged between the first rotating member and the tolerance ring, wherein the intermediate member has a connecting portion that connects the intermediate member to the first rotating member so that the intermediate member can rotate integrally with the first rotating member, and an extension portion that extends in the axial direction from the connecting portion, wherein the connecting portion is configured to be pressed into the outer periphery of the first rotating member, and the extension portion is configured to apply less pressure to the first rotating member than the connecting portion, and the tolerance ring is arranged on the outer periphery of the extension portion so as not to overlap with the axial range in which the connecting portion is provided.

[0009] According to the above configuration, the intermediate member is connected to the first rotating member so as to be rotatable together with the first rotating member by press-fitting the connecting portion into the outer periphery of the first rotating member. The extension portion is configured to apply a smaller pressure to the first rotating member than the connecting portion, so that the outer diameter of the intermediate member is less likely to change when the intermediate member is connected to the first rotating member. In addition, even if the outer diameter of the first rotating member changes, the outer diameter of the extension portion is less likely to change. And, since the tolerance ring is arranged so that the outer periphery of the extension portion does not overlap with the axial range in which the connecting portion is provided, the deformation amount of the spring portion of the tolerance ring is less likely to vary. This makes it possible to suppress variation in the friction force corresponding to the deformation amount of the spring portion, i.e., the slip torque, for each individual manufactured.

[0010] In the torque limiter, an annular space may be formed between an inner circumferential surface of the extension portion and an outer circumferential surface of the first rotating member. According to the above configuration, the extension portion does not contact the first rotating member, i.e., the pressure applied from the extension portion to the first rotating member is zero, so that the outer diameter of the extension portion is less likely to change when the outer diameter of the first rotating member changes. Also, with the above configuration, the extension portion can be deformed to reduce its diameter. Therefore, compared to a case where no annular space is formed between the extension portion and the first rotating member, for example, when the outer diameter of the extension portion becomes larger than the design value within the tolerance range, the amount of deformation of the spring portion of the tolerance ring can be suppressed from becoming excessive. This makes it possible to suitably suppress variation in slip torque between individual manufactured products.

[0011] In the above torque limiter, the first rotating member has a connected portion provided with external serrations extending along the axial direction, the connecting portion is provided with internal serrations extending along the axial direction and with which the external serrations are pressed into mesh, and at least one of the external serrations and the internal serrations may be provided with guide serrations that are axially continuous with the at least one serration and do not contribute to the connection of the intermediate member to the first rotating member.

[0012] According to the above configuration, when the intermediate member is connected to the first rotating member, at least one of the external serrations and the internal serrations is meshed with the guide serrations, thereby roughly circumferentially aligning the intermediate member with respect to the first rotating member. Since the guide serrations do not contribute to the connection of the intermediate member to the first rotating member, at least one of the external serrations and the internal serrations can be easily slid along the guide serrations. This allows the connection portion of the intermediate member to be easily press-fitted into the first rotating member, improving the ease of assembly of the intermediate member.

[0013] A steering device that solves the above problem comprises 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, and an annular intermediate member arranged between the steering shaft and the tolerance ring, wherein the intermediate member has a connecting portion that connects the intermediate member to the steering shaft so that it can rotate integrally with the steering shaft, and an extension portion that extends in the axial direction from the connecting portion, wherein the connecting portion is configured to be press-fitted into the outer periphery of the steering shaft, and the extension portion is configured to apply less pressure to the steering shaft than the connecting portion, and the tolerance ring is arranged on the outer periphery of the extension portion so as not to overlap with the axial range in which the connecting portion is provided. Effect of the Invention

[0014] According to the present invention, it is possible to suppress the variation in slip torque between individual manufactured products. [Brief description of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view taken along an axial direction of a steering device of a first embodiment. [Diagram 2] 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. FIG. [Diagram 3] 3 is a cross section perpendicular to the axial direction of a fitting portion of a key ring in the column shaft of the first embodiment, and is a cross section taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view showing the meshing of the external serrations of the column shaft and the internal serrations of the intermediate member. [Diagram 5] FIG. 11 is an enlarged cross-sectional view taken along the axial direction of a fitting portion of a key ring in a column shaft according to a second embodiment. [Figure 6] FIG. 11 is a cross-sectional view showing the engagement between the guide serrations of the column shaft and the guide serrations of the intermediate member. [Figure 7]FIG. 11 is an enlarged cross-sectional view taken along the axial direction of a fitting portion of a key ring in a column shaft according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] (First embodiment) Hereinafter, a first embodiment in which a torque limiter is applied to a steering lock mechanism of a steering device will be described with reference to the drawings.

[0017] In this specification, the term "annular" refers to a shape that can be considered as a whole annular, and includes a shape formed by combining multiple parts or portions into an annular shape, and a shape that has a notch or the like in a C-shape. The shape of the "annular" includes, but is not limited to, a circle, an ellipse, and a polygon with sharp or rounded corners when viewed in the axial direction. The shape of the "cylindrical" refers to a shape that can be considered as a whole annular, and includes a shape formed by combining multiple parts or portions into an annular shape, and a shape that has a notch or the like in a C-shape. The shape of the "cylindrical" refers to, but is not limited to, a circle, an ellipse, and a polygon with sharp or rounded corners when viewed in the axial direction. The shape of the "rod" refers to a shape that can be considered as a whole annular, and includes a shape formed by combining multiple parts or portions into an annular shape, and a shape that has a notch or the like in a C-shape. The shape of the "rod" refers to, but is not limited to, a circle, an ellipse, and a polygon with sharp or rounded corners when viewed in the axial direction.

[0018] (Overall composition) As shown in FIG. 1, the steering device 1 includes a column shaft 3 constituting 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 be generally aligned 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, the 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. An intermediate shaft and a pinion shaft (both not shown) constituting 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. In other words, the steering device 1 of this embodiment is a steering device in which the rotation of the steering wheel 6 is mechanically transmitted to a steering section that turns the steered wheels. Although detailed explanation is omitted, the steering device 1 has 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 speed of rotation of the motor 11. The speed reduction mechanism 12 is, for example, a worm reduction gear. The electric actuator 5 reduces the speed of rotation of the motor 11 and transmits it to the column shaft 3, thereby providing an assist force.

[0021] In detail, the column shaft 3 includes an upper shaft 21, an intermediate shaft 22 which is a first rotating member and a first shaft, a torsion bar 23 which is a second shaft, and a lower shaft 24.

[0022] The upper shaft 21 has a long cylindrical shape. The upper shaft 21 of the present embodiment has 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 of the present embodiment has 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 together with the intermediate shaft 22 and to be 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 to the outer periphery of the fitting portion 25 of the intermediate shaft 22 via an intermediate member 52 and a tolerance ring 53, as described later.

[0023] The torsion bar 23 has a long rod shape. The torsion bar 23 of this embodiment has a circular shape when viewed in the axial direction. The lower shaft 24 has a long cylindrical shape. The lower shaft 24 of this embodiment has 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 connected 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 connected to the lower shaft 24 so as to be rotatable together with the intermediate shaft 22. In other words, the lower shaft 24 is connected to the intermediate shaft 22 via the torsion bar 23 so as to be rotatable together with the intermediate shaft 22 and the lower shaft 24, for example, by being serrated-fitted to them.

[0024] A worm wheel 27 constituting the reduction gear mechanism 12 is connected to the lower shaft 24 so as to be rotatable therewith. The motor 11 is connected to the worm wheel 27 via a worm shaft (not shown) constituting the reduction gear mechanism 12. As a result, the rotation of the motor 11 is reduced in speed by the reduction gear mechanism 12 and transmitted to the lower shaft 24, thereby providing an assist force.

[0025] The steering column 4 includes a cylindrical inner tube 31 and an outer tube 32 that rotatably accommodate the upper shaft 21, and a housing 33 that constitutes the electric actuator 5. In this embodiment, the inner tube 31 and the outer tube 32 have 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, and they operate together even during so-called telescopic movement, but are configured to move relatively in the axial direction and contract when an impact load due to a vehicle collision or the like is applied.

[0026] 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 gear 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.

[0027] (Key ring fitting structure) Next, a description will be given of the fitting structure of the key ring 51 constituting the steering lock mechanism S. The steering lock mechanism S is configured to restrict the rotation of the column shaft 3 when a vehicle startup switch such as an ignition switch or a start switch is off.

[0028] 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 response to frictional force generated between the tolerance ring 53 and the key ring 51 and intermediate member 52 by restricting 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.

[0029] More specifically, as shown in Figs. 1 and 2, the fitting portion 25 has a flange portion 61 provided in its axial center, a connected portion 62 continuing to the rear side of the flange portion 61, and a circular portion 63 continuing to the rear side of the connected portion 62. The flange portion 61 is annular and extends radially outward. The flange portion 61 of this embodiment has a circular shape when viewed in the axial direction. The connected portion 62 is provided with a plurality of external tooth serrations 64. The external tooth serrations 64 protrude radially outward and extend axially rearward from the flange portion 61. The outer peripheral surface of the circular portion 63 is smooth and cylindrical. The outer diameter of the circular portion 63 is set to be equal to or smaller than the outer diameter of the tooth bottom of the external tooth serrations 64.

[0030] As shown in Figures 2 and 3, the key ring 51 is annular. The key ring 51 of this embodiment 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, for example, groove-shaped extending in the axial direction. 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 annular storage recess 72 that is open to the rear side.

[0031] The tolerance ring 53 is annular. The tolerance ring 53 of this embodiment has a C-shape when viewed in the axial direction. The tolerance ring 53 is formed by bending a plate-shaped 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 substantially rectangular shape that bulges outward in the radial direction. The plurality of spring portions 53a are formed, for example, at equal angular intervals in the circumferential direction of the tolerance ring 53, and are formed 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 is annular. The intermediate member 52 of this embodiment has a circular shape when viewed in the axial direction. The intermediate member 52 has a connecting portion 81 that connects the intermediate member 52 to the column shaft 3 so as to be rotatable together with the column shaft 3, and an extending portion 82 that extends from the connecting portion 81 to the rear side along 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 area of ​​the intermediate member 52. The predetermined outer diameter is an outer diameter at which the compression amount of the spring portion 53a compressed in the radial direction between the key ring 51 and the intermediate member 52 becomes a predetermined compression 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] The inner peripheral surface of the connecting portion 81 is provided with a plurality of internal serrations 83 that protrude radially inward. The internal serrations 83 extend from the front end face of the intermediate member 52 to the rear side along the axial direction. The length of the internal serrations 83 along the axial direction is set to be approximately equal to the length of the external serrations 64 along the axial direction. The inner peripheral surface of the extending portion 82 is smooth and cylindrical. The inner diameter of the extending portion 82 is set to be equal to or greater than the inner diameter of the internal serrations 83 at the tooth bottom, and is larger than the outer diameter of the circular portion 63. The length of the extending portion 82 along the axial direction is set to be longer than the length of the tolerance ring 53 along the axial direction.

[0034] As shown in FIG. 4, the tooth thickness of the external serrations 64 is set to be larger than the tooth groove width of the internal serrations 83. As a result, the connecting portion 81 is configured to be press-fitted onto the outer periphery of the intermediate shaft 22. Note that the tooth thickness of the external serrations 64 may be constant along the axial direction or may vary along the axial direction, so long as it is larger than the tooth groove width of the internal serrations 83. Similarly, the tooth groove width of the internal serrations 83 may be constant along the axial direction or may vary along the axial direction, so long as it is smaller than the tooth thickness of the external serrations 64. Note that, in FIG. 4, since the intermediate member 52 is connected to the fitting portion 25 of the intermediate shaft 22, the tooth thickness of the external serrations 64 is shown to be equal to the tooth groove width of the internal serrations 83 for convenience.

[0035] 2 and 3, the intermediate member 52 is serration-fitted to the intermediate shaft 22 by meshing the internal serrations 83 with the external serrations 64 of the fitting portion 25 in a press-fit state. This allows the intermediate member 52 to be connected to the intermediate shaft 22 (i.e., the column shaft 3) so as to be rotatable together with the intermediate shaft 22. A front end of the intermediate member 52 abuts against the flange portion 61.

[0036] As described above, the outer peripheral surface of the circular portion 63 and the inner peripheral surface of the extending portion 82 are smooth and cylindrical. Since the inner diameter of the extending portion 82 is larger than the outer diameter of the circular portion 63, an annular gap is formed between the outer peripheral surface of the fitting portion 25 and the inner peripheral surface of the intermediate member 52. Therefore, the intermediate shaft 22 does not receive pressure from the extending portion 82 of the intermediate member 52. That is, in this embodiment, the intermediate member 52 is connected to the intermediate shaft 22 only by the connecting portion 81, and the extending portion 82 does not contribute to the connection of the intermediate member 52 to the intermediate shaft 22. In other words, the pressure acting from the extending portion 82 to the intermediate shaft 22 is smaller than the pressure acting from the connecting portion 81 to the intermediate shaft 22. The tolerance ring 53 is disposed between the intermediate member 52 and the key ring 51 so as not to overlap the outer periphery of the extending portion 82 with the axial range L1 in which the connecting portion 81 is provided. In other words, the axial range L2 in which the tolerance ring 53 is provided does not overlap with the axial range L1 in which the connecting portion 81 is provided.

[0037] In the steering lock mechanism S configured in this manner, when the lock bar B is inserted into the insertion portion 71 of the key ring 51, rotation of the key ring 51 is restricted. Therefore, when the torque input to the column shaft 3 is less than the slip torque, rotation of the column shaft 3 is restricted. On the other hand, when the torque input to the column shaft 3 is equal to or greater than the slip torque, the column shaft 3 rotates relative to the tolerance ring 53, thereby allowing its rotation.

[0038] Next, the attachment of the key ring 51 to the column shaft 3 will be described. First, the key ring 51 is fitted onto the outer periphery of the intermediate member 52 via the tolerance ring 53 so that the tolerance ring 53 is positioned on the outer periphery of the extension portion 82 of the intermediate member 52. In this way, a key ring unit is manufactured in which the key ring 51, the tolerance ring 53 and the intermediate member 52 are integrated together.

[0039] Next, using an inspection device (not shown), the intermediate member 52 and the tolerance ring 53 of the manufactured key ring unit are rotated relative to one another to measure the slip torque. If the measured slip torque is within the design allowable range, the connecting portion 81 of the intermediate member 52 is press-fitted into the connected portion 62 of the fitting portion 25, thereby attaching the key ring unit to the intermediate shaft 22.

[0040] Next, the operation and effects of this embodiment will be described. (1) The intermediate member 52 has a connecting portion 81 that connects the intermediate member 52 to the intermediate shaft 22 so as to be rotatable together with the intermediate shaft 22, and an extending portion 82 that extends in the axial direction from the connecting portion 81. The connecting portion 81 is configured to be press-fitted into the outer periphery of the intermediate shaft 22, and the extending portion 82 is configured to apply less pressure to the intermediate shaft 22 than the connecting portion 81. The tolerance ring 53 is disposed on the outer periphery of the intermediate member 52 so as not to overlap with the axial range L1 in which the connecting portion 81 is provided.

[0041] According to the above configuration, the intermediate member 52 is connected to the intermediate shaft 22 so as to be rotatable together with the intermediate shaft 22 by press-fitting the connecting portion 81 into the outer periphery of the intermediate shaft 22. The extension portion 82 is configured to apply a smaller pressure to the intermediate shaft 22 than the connecting portion 81, so that the outer diameter of the extension portion 82 is less likely to change when the intermediate member 52 is connected to the intermediate shaft 22. In addition, even if the outer diameter of the fitting portion 25 of the intermediate shaft 22 is changed by press-fitting the torsion bar 23 into the fitting hole 26 of the fitting portion 25, the outer diameter of the extension portion 82 is less likely to change. In addition, the tolerance ring 53 is disposed on the outer periphery of the extension portion 82 so as not to overlap with the axial range L1 in which the connecting portion 81 is provided, so that the deformation amount of the spring portion 53a of the tolerance ring 53 is less likely to vary. This makes it possible to suppress the friction force according to the deformation amount of the spring portion 53a, i.e., the slip torque, from varying for each individual manufactured.

[0042] (2) An annular gap is formed between the inner peripheral surface of the extension portion 82 and the outer peripheral surface of the circular portion 63 of the intermediate shaft 22. Therefore, the extension portion 82 does not contact the intermediate shaft 22, i.e., the pressure applied from the extension portion 82 to the intermediate shaft 22 is zero, so that the outer diameter of the extension portion 82 is less likely to change when the outer diameter of the fitting portion 25 changes. In addition, in the above configuration, the extension portion 82 can be deformed to reduce its diameter. Therefore, compared to a case where no annular space is formed between the extension portion 82 and the intermediate shaft 22, for example, when the outer diameter of the extension portion 82 becomes larger than the design value within the tolerance range, the amount of deformation of the spring portion 53a of the tolerance ring 53 can be suppressed from becoming excessive. This makes it possible to suitably suppress variation in slip torque between individual manufactured products.

[0043] (3) Because the key ring 51 is fitted onto the outer periphery of the intermediate shaft 22 via the tolerance ring 53 and the intermediate member 52, a key ring unit configured to be able to measure the slip torque can be manufactured before the key ring 51 is attached to the column shaft 3. Therefore, compared to a configuration in which the key ring 51 is fitted onto the outer periphery of the intermediate shaft 22 via only the tolerance ring 53, for example, it is possible to inspect whether the slip torque is within the allowable range in a small size. This makes it easier to manufacture the steering device 1.

[0044] Second embodiment Next, a second embodiment in which the torque limiter is applied to a steering lock mechanism of a steering device will be described with reference to the drawings. For convenience of explanation, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

[0045] 5, in this embodiment, the circular portion 63 of the fitting portion 25 is provided with an external tooth guide serration 91 that extends axially continuously from the rear end of the external tooth serration 64. The external tooth guide serration 91 extends axially to the rear end of the circular portion 63. The tooth thickness of the external tooth guide serration 91 is set smaller than the tooth groove width of the internal tooth serration 83.

[0046] The tooth thickness of the external tooth guide serration 91 may be constant along the axial direction or may vary along the axial direction, so long as it is smaller than the tooth gap width of the internal tooth serration 83. When the tooth thickness of the external tooth guide serration 91 varies along the axial direction, the tooth thickness may change stepwise or continuously at the boundary position between the external tooth serration 64 and the external tooth guide serration 91.

[0047] In this embodiment, the extending portion 82 of the intermediate member 52 is provided with an internal tooth guide serration 92 that extends axially continuously from the rear end of the internal tooth serration 83. The internal tooth guide serration 92 extends in the axial direction to the rear end of the extending portion 82. The tooth groove width of the internal tooth guide serration 92 is set to be larger than the tooth thickness of the external tooth serration 64.

[0048] The tooth gap width of the internal tooth guide serration 92 may be constant along the axial direction or may vary along the axial direction, so long as it is greater than the tooth thickness of the external tooth serration 64. When the tooth gap width of the internal tooth guide serration 92 varies along the axial direction, the tooth gap width may change stepwise or continuously at the boundary position between the internal tooth serration 83 and the internal tooth guide serration 92.

[0049] 6, in a state in which the intermediate member 52 is connected to the fitting portion 25 so as to be rotatable together with the intermediate member 52, a gap is formed over the entire circumferential area between the external tooth guide serrations 91 and the internal tooth guide serrations 92. Therefore, the external tooth guide serrations 91 and the internal tooth guide serrations 92 do not contribute to the connection of the intermediate member 52 to the intermediate shaft 22.

[0050] As described above, in this embodiment, in addition to the same actions and effects as those of (1) and (2) of the first embodiment, the following actions and effects are achieved. (3) The external serrations 64 are provided with external guide serrations 91 that are continuous with the external serrations 64 in the axial direction and do not contribute to the connection of the intermediate member 52 to the intermediate shaft 22. The internal serrations 83 are provided with internal guide serrations 92 that are continuous with the internal serrations 83 in the axial direction and do not contribute to the connection of the intermediate member 52 to the intermediate shaft 22.

[0051] According to the above configuration, when connecting the intermediate member 52 to the intermediate shaft 22, the internal serrations 83 are meshed with the external guide serrations 91, thereby roughly circumferentially aligning the intermediate member 52 with respect to the intermediate shaft 22. Since the tooth thickness of the external guide serrations 91 is smaller than the tooth groove width of the internal serrations 83, the internal serrations 83 can easily slide along the external guide serrations 91. This allows the connecting portion 81 of the intermediate member 52 to be easily press-fitted into the intermediate shaft 22, improving the ease of assembly of the intermediate member 52.

[0052] Third embodiment Next, a third embodiment in which the torque limiter is applied to a steering lock mechanism of a steering device will be described with reference to the drawings. For convenience of explanation, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

[0053] As shown in FIG. 7, the torsion bar 23 is not directly pressed into the fitting portion 25 of the intermediate shaft 22, which is the first shaft of this embodiment, but is pressed into the fitting portion 25 via the connecting shaft 101, which is the second shaft. Specifically, the inner diameter of the fitting hole 26 of this embodiment is set to be larger than the inner diameter of the fitting hole 26 of the first embodiment. The connecting shaft 101 has a long cylindrical shape. The connecting shaft 101 of this embodiment has a circular shape when viewed in the axial direction. The shape of the connecting shaft 101 may be similar to the front part of the intermediate shaft 22 of the first embodiment, for example, relative to the flange portion 61. The rear end of the torsion bar 23 is pressed into an opening at the rear end of the connecting shaft 101, and is connected to the connecting shaft 101 so as to be rotatable together with the connecting shaft 101. The front end of the torsion bar 23 is pressed into an opening at the front end of the lower shaft 24, and is connected to the lower shaft 24 so as to be rotatable together with the connecting shaft 101, as in the first embodiment. In other words, the connecting shaft 101 is connected to the lower shaft 24 via the torsion bar 23 .

[0054] The axial length of the fitting portion 25 of this embodiment is shorter than that of the fitting portion 25 of the first embodiment, and the flange portion 61 is provided at the front end portion of the fitting portion 25. The rear end portion of the connecting shaft 101, into which the torsion bar 23 is press-fitted, is press-fitted into the fitting hole 26. As a result, the connecting shaft 101 is connected to the intermediate shaft 22 so as to be rotatable together with the intermediate shaft 22.

[0055] The fitting portion 25 also has a circular portion 111 continuing to the rear side of the flange portion 61, and a connected portion 112 continuing to the rear side of the circular portion 111. The outer peripheral surface of the circular portion 111 is smooth and cylindrical, similar to the first embodiment. The connected portion 112 is provided with a plurality of external serrations 113 adjacent to the rear side of the circular portion 111. The external serrations 113 are configured similarly to the external serrations 64 of the first embodiment. The outer diameter of the circular portion 111 is set to be equal to or smaller than the outer diameter of the external serrations 113 at the tooth base.

[0056] The intermediate member 52 is connected to the fitting portion 25 by press-fitting the internal serrations 83 into the external serrations 113 in a state inverted in the front-to-rear direction from that of the first embodiment. The key ring 51 and the tolerance ring 53 are also fitted onto the outer periphery of the intermediate member 52 in a state inverted in the front-to-rear direction from that of the first embodiment.

[0057] As described above, this embodiment provides the same functions and effects as those of (1) and (2) of the first embodiment. The above-described embodiments may be modified as follows: The above-described embodiments and the following modifications may be combined with each other to the extent that no technical contradiction occurs.

[0058] In each of the above embodiments, a key ring unit is manufactured by integrating the key ring 51, the tolerance ring 53, and the intermediate member 52, and then the key ring unit is attached to the intermediate shaft 22. However, this is not limited to the above, and the key ring unit may not be manufactured first, and the key ring 51 and the tolerance ring 53 may be attached after the intermediate member 52 is attached to the intermediate shaft 22.

[0059] In the second embodiment, the guide serrations may be provided on only one of the external serrations 64 and the internal serrations 83. In the third embodiment, the guide serrations may be provided on at least one of the external serrations 113 and the internal serrations 83.

[0060] In the above embodiments, the connecting portion 81 is provided with the internal serrations 83, and the connected portions 62, 112 are provided with the external serrations 64, 113, but the present invention is not limited to this. The inner peripheral surface of the connecting portion 81 and the outer peripheral surfaces of the connected portions 62, 112 may both be formed cylindrically. The connecting portion 81 may be press-fitted onto the outer periphery of the connected portions 62, 112 so that the intermediate member 52 rotates integrally with the intermediate shaft 22. In other words, as long as the intermediate member 52 can be connected to the intermediate shaft 22 so as to be integrally rotatable with the intermediate shaft 22, the intermediate member 52 does not need to be serrated-fitted to the intermediate shaft 22.

[0061] In the first embodiment, an annular gap does not have to be formed between the inner peripheral surface of the extending portion 82 and the outer peripheral surface of the circular portion 63. In this case, the extending portion 82 may be press-fitted (lightly press-fitted) into the circular portion 63 if the pressure applied to the intermediate shaft 22 is smaller than that of the connecting portion 81. In other words, the extending portion 82 may be press-fitted into the circular portion 63 if the press-fit allowance of the extending portion 82 into the circular portion 63 is smaller than the press-fit allowance of the connecting portion 81 into the connected portion 62. Similarly, in the second and third embodiments, an annular gap does not have to be formed between the inner peripheral surface of the extending portion 82 and the outer peripheral surfaces of the circular portions 63, 111.

[0062] The steering device 1 may be a steer-by-wire type steering device in which power transmission is separated between a steering section steered by a driver and a steering section that steers the steered wheels in response to steering by the driver.

[0063] In addition to the steering lock mechanism S of the steering device 1, a torque limiter may be applied. Next, the technical ideas that can be understood from the above-described embodiments and modifications will be described below.

[0064] (Additional 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 positioned on the outer periphery of the fitting portion of the first shaft in which the fitting hole is provided. [Explanation of symbols]

[0065] 1...Steering device 2...Steering shaft 22...Intermediate shaft 51...Key ring 52...Intermediate member 53…Tolerance ring 53a…Spring part 81...Connection part 82...Extending part

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 rotating member and the second rotating 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; The intermediate member has a connecting portion that connects the intermediate member to the first rotating member so as to be rotatable together with the first rotating member, and an extending portion that extends in an axial direction from the connecting portion, The connecting portion is configured to be press-fitted onto an outer periphery of the first rotating member, The extension portion is configured to apply a smaller pressure to the first rotating member than the connecting portion, A torque limiter, wherein the tolerance ring is disposed on an outer periphery of the extension portion so as not to overlap with an axial range in which the connecting portion is provided.

2. The torque limiter according to claim 1 , wherein an annular space is formed between an inner circumferential surface of the extension portion and an outer circumferential surface of the first rotating member.

3. The first rotating member has a connected portion provided with external serrations extending along the axial direction, The connecting portion is provided with an internal serration extending along an axial direction and meshing with the external serration in a press-fit state, 3. The torque limiter according to claim 1, wherein at least one of the external tooth serrations and the internal tooth serrations is provided with a guide serration that is axially continuous with the at least one of the serrations and does not contribute to the connection of the intermediate member to the first rotating member.

4. A steering shaft; an annular key ring disposed on an 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, the intermediate member has a connecting portion that connects the intermediate member to the steering shaft so as to be rotatable together with the steering shaft, and an extending portion that extends in an axial direction from the connecting portion, The connecting portion is configured to be press-fitted onto an outer periphery of the steering shaft, The extension portion is configured to apply a smaller pressure to the steering shaft than the connecting portion, A steering device, wherein the tolerance ring is disposed on an outer periphery of the extension portion so as not to overlap with an axial range in which the connecting portion is provided.

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