Power transmission device for a steering arrangement

Abstract

The present invention provides a power transmission device of a steering device, including: a first coupling member including a first large diameter portion protruding radially and a first coupling hole formed at a central portion of the first coupling member, and coupled to any one of a first shaft and a second shaft; a second coupling member including a second large diameter portion protruding radially at a position corresponding to the first large diameter portion and a second coupling hole formed at a central portion of the second coupling member, and coupled to the other of the first shaft and the second shaft; and an intermediate member including an insertion end coupled between the first large diameter portion and the second large diameter portion and an elastically deformable elastic protrusion, and coupled between the first coupling member and the second coupling member.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2020-0143517, filed with the Korean Intellectual Property Office on October 30, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to a power transmission device for a steering system. More specifically, this disclosure relates to a power transmission device for a steering system that, compared to conventional power transmission devices, is capable of: accurately transmitting rotational force from a first shaft to a second shaft while maintaining rigidity without vibration or noise; absorbing vibration and noise caused by heat or shock; and enhancing durability. Background Technology

[0004] Typically, a vehicle steering system is a device that enables the driver to change the direction of the vehicle's travel by turning the steering wheel. A vehicle steering system is an auxiliary device used to assist the driver in steering the vehicle in the desired direction by changing the desired angle around a center of rotation about which the front wheels of the vehicle rotate. In such steering systems, electric power steering is used as an auxiliary power mechanism to reduce the force required for the driver to turn the steering wheel.

[0005] Electric power steering has a structure that detects the rotation of the steering wheel and drives a motor mounted on a rack or steering shaft to assist the rotational movement, thereby enabling the steering system to operate effectively.

[0006] However, in the power transmission mechanism of such traditional electric power steering systems, when the durability of the power transmission mechanism decreases due to prolonged use, or when driving on roads, such as off-road, large impacts can be transmitted in the reverse direction through the steering shaft. This results in drawbacks such as increased noise, wear, and play due to contact.

[0007] In particular, traditional power transmission devices have some drawbacks, such as increased rattling and noise, and reduced stiffness caused by aging, wear, and permanent compression due to high temperatures in the power transmission device after its durability is reduced. Summary of the Invention

[0008] To address these issues, embodiments of this disclosure provide a power transmission device for a steering system that, compared to conventional power transmission devices, is capable of: transmitting rotational force from a first shaft to a second shaft while maintaining rigidity without vibration or noise; absorbing noise caused by heat or impact; and enhancing durability.

[0009] The purpose of this disclosure is not limited thereto, and other purposes will be clearly understood by those skilled in the art from the following description.

[0010] According to an aspect of this disclosure, a power transmission device for a steering mechanism is provided, the power transmission device comprising: a first connecting member including a radially protruding first large-diameter portion and a first connecting hole formed in the central portion of the first connecting member, and connected to either a first shaft or a second shaft; a second connecting member including a radially protruding second large-diameter portion at a position corresponding to the first large-diameter portion and a second connecting hole formed in the central portion of the second connecting member, and connected to the other of the first shaft and the second shaft; and an intermediate member including an insertion end connected between the first large-diameter portion and the second large-diameter portion and an elastic protrusion located on the axial end face of the intermediate member, supported by the inner surface of the first connecting member and elastically deformable, and connected between the first connecting member and the second connecting member.

[0011] According to embodiments of the present disclosure, a power transmission device for a steering system can be provided, which, compared to conventional power transmission devices, is capable of: transmitting rotational force from a first shaft to a second shaft while maintaining rigidity without vibration or noise; absorbing noise caused by heat or impact; and enhancing durability. Attached Figure Description

[0012] The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in and constitute a part of this disclosure. The drawings illustrate aspects of this disclosure and, together with the description, serve to illustrate the principles of this disclosure. In the figures:

[0013] Figure 1 A steering device according to an aspect of this disclosure is schematically shown;

[0014] Figure 2 This is an exploded perspective view of the power transmission device of the steering device according to aspects of this disclosure;

[0015] Figure 3 This is a cross-sectional view of the power transmission device of the steering device according to aspects of this disclosure;

[0016] Figures 4 to 6 This is a perspective view of the power transmission device of the steering device according to aspects of this disclosure;

[0017] Figure 7 This is a front view of a part of the power transmission device of the steering device according to aspects of this disclosure;

[0018] Figure 8 This is a cross-sectional view of a portion of the power transmission device of the steering device according to aspects of this disclosure;

[0019] Figure 9 A perspective view of a portion of the power transmission device of the steering device according to aspects of this disclosure; and

[0020] Figure 10 and Figure 11 This is a cross-sectional view of the power transmission device of the steering device according to aspects of this disclosure. Detailed Implementation

[0021] In the following description of examples or embodiments of this disclosure, reference will be made to the accompanying drawings, in which specific examples or embodiments that may be implemented are illustrated by way of illustration, and the same reference numerals and symbols in the drawings may be used to denote the same or similar components even if shown in different drawings. Furthermore, in the following description of examples or embodiments of this disclosure, a detailed description of well-known functions and components incorporated herein will be omitted where it is determined that such detailed description may make the subject matter of some embodiments of this disclosure considerably unclear. Terms such as “comprising,” “having,” “including,” “constituting,” “forming,” and “form” as used herein are generally intended to allow for the addition of additional components, unless these terms are used in conjunction with the term “only.” As used herein, the singular forms are intended to include the plural forms unless the context clearly indicates otherwise.

[0022] Terms such as “first,” “second,” “A,” “B,” “(A),” or “(B)” may be used herein to describe elements of this disclosure. Each of these terms is not intended to define the nature, order, sequence, or number of elements, but only to distinguish the corresponding element from other elements.

[0023] When time-related terms such as “after,” “following,” “next,” or “before” are used to describe the processing or operation of an element or structure, or the flow or steps in an operation, processing, or manufacturing method, these terms may be used to describe non-continuous or non-sequential processing or operations, unless the terms “directly” or “immediately following” are used simultaneously.

[0024] Additionally, when referring to any size, relative dimensions, etc., the numerical values ​​or corresponding information of the component or feature (e.g., grade, range, etc.) should be considered, including tolerances or error ranges that may be caused by various factors (e.g., manufacturing factors, internal or external shocks, noise, etc.), even if no relevant description is given. Furthermore, the term "may" fully encompasses all the meanings of the term "can".

[0025] Figure 1 A steering device according to an aspect of this disclosure is schematically shown; Figure 2 This is an exploded perspective view of the power transmission device of the steering device according to aspects of this disclosure; Figure 3 This is a cross-sectional view of the power transmission device of the steering device according to aspects of this disclosure; Figures 4 to 6This is a perspective view of the power transmission device of the steering device according to aspects of this disclosure; Figure 7 This is a front view of a part of the power transmission device of the steering device according to aspects of this disclosure; Figure 8 This is a cross-sectional view of a portion of the power transmission device of the steering device according to aspects of this disclosure; Figure 9 This is a perspective view of a portion of the power transmission device of the steering device according to aspects of this disclosure; and Figure 10 and Figure 11 This is a cross-sectional view of the power transmission device of the steering device according to aspects of this disclosure.

[0026] As shown in these figures, the power transmission device 200 of the steering device according to an aspect of the present disclosure includes: a first connecting member 210, including a radially protruding first large-diameter portion 211 and a first connecting hole 212 formed in the central portion of the first connecting member 210, and connected to either a first shaft 201 or a second shaft 203; a second connecting member 220, including a radially protruding second large-diameter portion 221 at a position corresponding to the first large-diameter portion 211 and a second connecting hole 222 formed in the central portion of the second connecting member 220, and connected to the other of the first shaft 201 and the second shaft 203; and an intermediate member 230, including an insertion end 231 connected between the first large-diameter portion 211 and the second large-diameter portion 221 and an elastic protrusion 235 located on the axial end face of the intermediate member 230, supported on the inner surface 215a of the first connecting member 210 and elastically deformable, and connected between the first connecting member 210 and the second connecting member 220.

[0027] The power transmission device 200 can be coaxially connected to a first shaft 201 that is rotatable via a power source such as a motor or pump, and transmits rotational force (i.e., torque) from the power source to a second shaft 203. In the following description, embodiments of the power transmission device for a steering system according to aspects of this disclosure will be focused on, but not limited to, an electric power steering system including a motor shaft as the first shaft 201 and a worm shaft as the second shaft 203.

[0028] Furthermore, embodiments are discussed, but not limited to, whereby the first connecting member 210 is connected to the first shaft 201 and the second connecting member 220 is connected to the second shaft 203.

[0029] In these cases, it should be noted that the power transmission device 200 can be used as a power connection device for assisting the driver's steering force by connecting the shaft of the motor, which is configured to generate auxiliary power in an electric power steering system, and the worm shaft, and transmitting the auxiliary power generated by the motor to the steering shaft connected to the worm gear.

[0030] Here, as Figure 1As shown, the electric power steering system includes a steering mechanism 100 mechanically connected from a steering wheel 101 to two wheels 108, and an auxiliary power unit 120 for providing steering assistance power to the steering mechanism 100.

[0031] The steering mechanism 100 may include a steering shaft 102. One side of the steering shaft 102 may be connected to a steering wheel 101 to rotate together with the steering wheel 101, and the other side of the steering shaft 102 may be connected to a pinion shaft 104 via a pair of universal joints 103.

[0032] Furthermore, the pinion shaft 104 can be connected to the rack via the rack-pinion assembly 105, and both ends of the rack can be connected to the wheel 108 via the tie rod 106 and the steering knuckle arm 107. Since the rack-pinion assembly 105 is generated by the engagement of the pinion 111 formed on the pinion shaft 104 and the rack 112 formed on one side of the outer peripheral surface of the rack, when the driver turns the steering wheel 101, torque can be generated through the steering mechanism 100, thereby turning the wheel 108 through the rack-pinion assembly 105 and the tie rod 106.

[0033] The auxiliary power unit 120 may include a torque sensor 125 for detecting the torque applied to the steering wheel 101 by the driver and generating an electrical signal proportional to the applied torque, an electronic control unit (ECU) 123 for generating control signals based on the electrical signals sent from the torque sensor 125, a motor 130 for generating auxiliary power based on the signals sent from the ECU, and a reducer 140 for transmitting the auxiliary power provided by the motor 130 to the steering shaft 102.

[0034] Here, as Figures 2 to 10 As shown, in order for the power transmission device 200 to transmit power through the coaxial connection between the first shaft 201 and the second shaft 203, the first connecting member 210 and the second connecting member 220 of the power transmission device 200 can be connected to the first shaft 201 and the second shaft 203 respectively, and the intermediate member 230 can be connected between the first connecting member 210 and the second connecting member 220.

[0035] The first shaft 201, which serves as the motor shaft, is supported by the first housing 207 via the first bearing 202, and the second shaft 203, which serves as the worm shaft, is supported by the second housing 205 via the second bearing 204. The first shaft 201 and the second shaft 203 can be connected to each other via the power transmission device 200.

[0036] The first connecting member 210 may include one or more first large-diameter portions 211 that are radially projecting and circumferentially spaced from each other, and a first connecting hole 212 that is connected to the first shaft 201 and formed to pass through the central portion of the first connecting member 210.

[0037] Furthermore, one or more recesses 216, which are formed to descend radially in a stepped manner relative to the outer peripheral surface of the first large diameter portion 211, may be formed between adjacent first large diameter portions 211. Thus, the first large diameter portions 211 and the recesses 216 are arranged radially alternately.

[0038] The serrations formed axially on the inner circumferential surface of the first connecting hole 212 can be connected with the serrations formed axially on the first shaft 201, and the serrations formed axially on the first shaft 201 are formed to correspond to the serrations of the first connecting hole 212. Thus, the first shaft 201 can be prevented from spinning freely when it rotates.

[0039] The second connecting member 220 may include one or more second large diameter portions 221 that protrude radially at positions corresponding to one or more first large diameter portions 211 and are circumferentially spaced from each other, and a second connecting hole 222 formed to axially pass through the central portion of the second connecting member 220.

[0040] The serrations formed axially on the inner circumferential surface of the second connecting hole 222 can connect with the serrations formed axially on the second shaft 203, and the serrations formed axially on the second shaft 203 are formed to correspond to the serrations of the second connecting hole 222. Thus, the second shaft 203 can be prevented from spinning freely when it rotates.

[0041] The first connecting member 210 may include a cylindrical portion 213 and a radial portion 215. An intermediate member 230 and a second connecting member 220 are inserted into the cylindrical portion 213. The radial portion 215 extends inward from the inner peripheral end of the cylindrical portion 213 and has a first connecting hole 212 in the central portion of the first connecting member 210.

[0042] Furthermore, the intermediate member 230 connecting the first connecting member 210 and the second connecting member 220 may include one or more insertion ends 231 and one or more elastic protrusions 235. The one or more insertion ends 231 are respectively connected between the first large diameter portion 211 and the second large diameter portion 221, and the one or more elastic protrusions 235 are located on the axial end face of the intermediate member 230, supported on the inner surface 215a of the first connecting member 210, and are elastically deformable.

[0043] One or more protruding ends 231a, which are formed as radial protrusions, can be circumferentially formed on the outer peripheral surface of one or more insertion ends 231. Thus, when the intermediate member 230 is connected to the first connecting member 210, while being elastically compressed, the protruding ends 231a can support the inner peripheral surface of the first large diameter portion 211, thereby absorbing impact and noise.

[0044] Furthermore, one or more stepped descending portions 231b, which descend radially relative to the circumferential sides, are formed on the outer peripheral surface of one or more insertion ends 231 on the two circumferential sides of one or more protruding ends 231a. Thus, while being radially elastically compressed, the protruding ends 231a can absorb deformation caused by circumferential expansion from both sides of the protruding ends 231a.

[0045] Therefore, when the first connecting member 210 and the intermediate member 230 are connected, assembly or manufacturing errors in the radial and / or circumferential directions can be effectively absorbed, while maintaining the coaxial connection of the first shaft 201 and the second shaft 203 with rigidity.

[0046] In addition, the intermediate member 230 may include one or more inwardly recessed portions 233, each inwardly recessed portion 233 being formed between circumferentially adjacent insertion ends 231 and being formed to descend radially in a stepped manner relative to the insertion ends 231.

[0047] Here, when the first shaft 201 and the second shaft 203 are connected and rotated, when an impact load is input that deviates from the corresponding coaxial connection, the inwardly recessed portion 233 allows the insertion end 231 to easily deform elastically in the circumferential and radial directions. This effectively absorbs the corresponding vibrations and noise, and prevents deformation or damage to the first connecting member 210 and the second connecting member 220.

[0048] In particular, because the thermal expansion of the intermediate member 230 at high temperatures can be absorbed by the expansion of the inwardly recessed portion 233 in the circumferential direction, it can maintain rigidity and absorb noise caused by heat or impact when the rotational force is transmitted from the first shaft 201 to the second shaft 203.

[0049] The intermediate member 230 may include a cylindrical wall 239 and a radial wall 236. The second connecting member 220 is inserted into the cylindrical wall 239. The radial wall 236 extends inward from the circumferential end of the cylindrical wall 239 and has a through hole 237 formed in the central portion of the intermediate member 230. An insertion end 231, a protruding end 231a, a stepped descending portion 231b, an inwardly recessed portion 233, etc., may be formed on the outer surface of the cylindrical wall 239, and an elastic protrusion 235 may be formed on the outer surface of the radial wall 236.

[0050] The elastic protrusions 235 formed on the axial end face of the intermediate member 230, that is, on the outer surface of the radial wall 236, can be formed to be circumferentially spaced from each other. For example, as shown, each elastic protrusion 235 can be provided in each of the four insertion ends 231.

[0051] Each elastic protrusion 235 can be formed to axially protrude from the axial end face of each insertion end 231, and is thus connected while being elastically compressed during assembly. Therefore, axial impacts and loads can be effectively absorbed.

[0052] Furthermore, an empty space 235d is provided between the axial edge of the elastic protrusion 235 and the area connected to the insertion end 231. Thus, even if wear or permanent deformation of the intermediate member 230 occurs due to reduced durability, the elastic restoring force of the elastic protrusion 235 can be maintained above a certain level in addition to absorbing axial impact and load.

[0053] like Figures 6 to 8 As shown, the elastic protrusion 235 may include a connecting protrusion 235a that is connected to and axially protrudes from the axial end face of the insertion end 231, and a pair of support protrusions 235b. The pair of support protrusions 235b branch out from the edge of the connecting protrusion 235a to both sides and are spaced apart from each other to form a space 235d between the pair of support protrusions 235b. They have openings 235c formed between the edges of the pair of support protrusions 235b and communicating with the space 235d, and are elastically supported on the inner surface 215a of the first connecting member 210.

[0054] Since the connecting protrusion 235a has a larger cross-sectional area than the pair of support protrusions 235b, high stiffness between the insertion end 231 and the pair of support protrusions 235b can be ensured to support the elastic deformation of the pair of support protrusions 235b.

[0055] Here, the edges of a pair of support protrusions 235b can be formed to curve inward toward each other, such that the size of the opening 235c is smaller than the size of the space 235d.

[0056] Furthermore, the openings 235c of the pair of support protrusions 235b can be located on the inner surface 215a of the first connecting member 210, and the pair of support protrusions 235b can be formed into a cylindrical cross-sectional shape with a space 235d.

[0057] Therefore, since the pair of support protrusions 235b, which have relatively low stiffness compared to the connecting protrusion 235a, are assembled under elastic deformation, vibration and noise can be absorbed. Furthermore, when a strong impact is transmitted from the outside, the elastic deformation of the connecting protrusion 235a can absorb this impact.

[0058] like Figures 9 to 10 As shown, the elastic protrusion 235 may include a connecting protrusion 235a and a supporting protrusion 235b. The connecting protrusion 235a is connected to and protrudes axially from the axial end face of the insertion end 231. The supporting protrusion 235b includes an edge that bends radially toward a specific location from the edge of the connecting protrusion 235a, i.e., bends radially inward to form a space 235d therein, and is elastically supported on the inner surface 215a of the first connecting member 210.

[0059] In order to separate the edge of the support protrusion 235b from the inner surface 215a of the first connecting member 210, the outer surface of the support protrusion 235b supported on the first connecting member 210 can be formed to have an outwardly curved shape. In this way, when the first shaft 201 and the second shaft 203 rotate, wear and other damage caused by excessive contact between the support protrusion 235b and the first connecting member 210 can be minimized and friction noise reduced.

[0060] Furthermore, since the inner surface of the connecting protrusion 235a connected to the support protrusion 235b, that is, the inner surface of the space 235d formed by the radial wall 236 of the through hole 237 of the intermediate member 230 and the surrounding of the support protrusion 235b, is formed to have a curved shape, the elastic deformation of the support protrusion 235b can continue even if the durability is reduced.

[0061] like Figure 11 As shown, the elastic protrusion 235 may include a connecting protrusion 235a and a pair of support protrusions 235b. The connecting protrusion 235a is connected to and protrudes axially from the axial end face of the insertion end 231. The pair of support protrusions 235b includes edges that are bent radially from the edge of the connecting protrusion 235a to form a space 235d between the pair of support protrusions 235b, and are elastically supported on the inner surface 215a of the first connecting member 210.

[0062] In this configuration, because the thickness of each of the pair of support protrusions 235b is less than the thickness of the connecting protrusion 235a, the pair of support protrusions 235b can be assembled under elastic deformation, thereby absorbing vibration and noise. Furthermore, when a strong impact is transmitted from the outside, the elastic deformation of the connecting protrusion 235a can absorb this impact.

[0063] Therefore, when the first shaft 201 and the second shaft 203 are connected and rotate normally, vibration and noise can be absorbed by the elastic support force of a pair of support protrusions 235b, and when strong impacts are transmitted from the outside, such as uneven road surfaces, such impacts can be absorbed by the elastic support force of the connecting protrusions 235a.

[0064] The first connecting member 210 and the second connecting member 220 may include metallic materials such as steel or engineering plastic-based materials such as polyacetal (POM), polyamide (PA), polycarbonate (PC), polyimide (PI), polybutylene terephthalate (PBT), etc.

[0065] In addition, to provide weather resistance, flexibility, and elasticity, the intermediate component 230 may include materials such as natural rubber (NR), nitrile rubber (NBR), chloroprene rubber (CR), ethylene propylene diene monomer (EPDM), fluororubber (FPM), styrene-butadiene rubber (SBR), chlorosulfonated polyethylene (CSM), urethane, and silicone, and act as a damper to absorb noise and vibration.

[0066] According to the structure and shape of the embodiments described herein, a power transmission device for a steering system can be provided that, compared with conventional power transmission devices, is capable of: transmitting rotational force from a first shaft to a second shaft while maintaining rigidity without vibration or noise; absorbing noise caused by heat or shock; and enhancing durability.

[0067] The foregoing description has been provided to enable those skilled in the art to make and use the technical ideas of this disclosure, and has been provided in the context of a particular application and its requirements. Various modifications, additions, and substitutions to the described embodiments will be apparent to those skilled in the art without departing from the spirit and scope of this disclosure, and the general principles defined herein can be applied to other embodiments and applications. The foregoing description and drawings provide examples of the technical ideas of this disclosure for illustrative purposes only. That is, the disclosed embodiments are intended to illustrate the scope of the technical ideas of this disclosure. Therefore, the scope of this disclosure is not limited to the embodiments shown, but is consistent with the widest scope consistent with the claims. The scope of protection of this disclosure should be interpreted based on the appended claims, and all technical ideas within the equivalent scope of the appended claims should be interpreted as included within the scope of this disclosure.

Claims

1. A power transmission device for a steering system, comprising: The first connecting member includes a radially protruding first large-diameter portion and a first connecting hole formed in the central portion of the first connecting member, and is connected to either the first shaft or the second shaft; The second connecting member includes a second large diameter portion that protrudes radially at a position corresponding to the first large diameter portion and a second connecting hole formed in the central portion of the second connecting member, and is connected to the other of the first shaft and the second shaft; as well as The intermediate component includes an insertion end connected between the first large-diameter portion and the second large-diameter portion, and an elastic protrusion disposed on the axial end face of the intermediate component, supported on the inner surface of the first connecting component, and elastically deformable, and is connected between the first connecting component and the second connecting component. The radially protruding protrusion is circumferentially disposed on the outer peripheral surface of the insertion end, and A stepped descending portion, which is provided on the two circumferential sides of the protruding end and descends radially relative to the circumferential sides, is provided on the outer circumferential surface of the insertion end.

2. The power transmission device for the steering system according to claim 1, wherein, The serrations are axially positioned on the inner circumferential surface of the first connecting hole.

3. The power transmission device for the steering system according to claim 1, wherein, The first connecting member includes: Cylindrical portion, the intermediate member and the second connecting member are inserted into the cylindrical portion; and The radial portion extends inward from the inner circumferential end of the cylindrical portion and has the first connecting hole in the central portion of the first connecting member.

4. The power transmission device for the steering system according to claim 1, wherein, The serrations are axially positioned on the inner circumferential surface of the second connecting hole.

5. The power transmission device for the steering system according to claim 1, wherein, The insertion end includes a plurality of insertion ends, and the intermediate member includes one or more inwardly recessed portions that descend radially in a stepped manner relative to the plurality of insertion ends between the plurality of circumferentially adjacent insertion ends.

6. The power transmission device for the steering system according to claim 1, wherein, The elastic protrusions include a plurality of elastic protrusions that are circumferentially spaced apart from each other.

7. The power transmission device for the steering system according to claim 1, wherein, The elastic protrusion includes multiple elastic protrusions, and the insertion end includes multiple insertion ends. Each of the plurality of elastic protrusions protrudes axially from the axial end face of each of the plurality of insertion ends.

8. The power transmission device for the steering device according to claim 7, wherein, The elastic protrusion has a space between its axial edge and the area connected to the insertion end.

9. The power transmission device for the steering system according to claim 8, wherein, The elastic protrusion includes: A connecting protrusion, connected to and protruding axially from the axial end face of the insertion end; and A pair of support protrusions branch out from the edge of the connecting protrusion to both sides, spaced apart from each other to form the space, having an opening formed between the edges of the pair of support protrusions and communicating with the space, and elastically supported on the inner surface of the first connecting member.

10. The power transmission device for the steering system according to claim 9, wherein, The edges of the pair of support protrusions are formed to curve inward toward each other, such that the size of the opening is smaller than the size of the space.

11. The power transmission device for the steering system according to claim 9, wherein, The opening is located on the inner surface of the first connecting member, and the pair of support protrusions have a cylindrical cross-sectional shape with the space provided.

12. The power transmission device for the steering system according to claim 8, wherein, The elastic protrusion includes: A connecting protrusion, connected to and protruding axially from the axial end face of the insertion end; and The support protrusion includes an edge that bends radially toward a specific location from the edge of the connecting protrusion to form the space, and is elastically supported on the inner surface of the first connecting member.

13. The power transmission device for the steering device according to claim 12, wherein, The outer surface of the support protrusion, which rests on the inner surface of the first connecting member, has an outwardly curved surface such that the edge of the support protrusion is spaced apart from the inner surface of the first connecting member.

14. The power transmission device for the steering system according to claim 12, wherein, The area where the connecting protrusion connects to the supporting protrusion has a curved shape.

15. The power transmission device for the steering system according to claim 8, wherein, The elastic protrusion includes: A connecting protrusion, connected to and protruding axially from the axial end face of the insertion end; and A pair of support protrusions, including edges that bend radially to both sides from the edge of the connecting protrusion to form the edge of the space, and are elastically supported on the inner surface of the first connecting member.

16. The power transmission device for the steering system according to claim 15, wherein, The thickness of each of the pair of support protrusions is less than the thickness of the connecting protrusion.

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