Patent Publication Number: US-2022234649-A1

Title: Steer-by-wire type steering apparatus

Description:
TECHNICAL FIELD 
     Embodiments of the present disclosure relate generally to a steer-by-wire steering apparatus and, more particularly, to a steer-by-wire steering apparatus limiting driver&#39;s operation of the steering wheel within a minimum angle of rotation so as to improve driver&#39;s feeling of steering and prevent a clock spring disposed on the steering wheel from being damaged, wherein parts of the steering apparatus may be more easily fabricated and machined and more simply fitted together, and the interference of the parts with surrounding components may be reduced, so that the steer-by-wire steering apparatus may be designed in a variety of structures and advantageous for packaging. 
     BACKGROUND ART 
     A steer-by-wire steering apparatus is a type of electric steering apparatus, and steers a vehicle using electric power without a mechanical connection, such as a steering column or a universal joint, between a steering wheel and a front wheel steering apparatus. 
     That is, driver&#39;s operation of the steering wheel is converted into an electrical signal. When the electrical signal is input into an electronic control device, the output of a motor is determined. Such an SBW system with no mechanical connection may reduce injury to a driver caused by a mechanical part in a collision accident. Since the mechanical connection and hydraulic parts may be removed, the weight of a vehicle may be reduced due to the reduced number of parts, and simplification such as significantly reduced line assembly work may be realized. In addition, unnecessary energy consumption during a steering operation may be reduced, thereby improving fuel efficiency. In addition, ideal steering performance may be realized by electronic control unit (ECU) programming. 
     Since there are no mechanical connections between a steering shaft and wheels, such a steer-by-wire steering apparatus requires a device limiting a driver so as not to further turn the steering wheel at a maximum angle. However, there is problem in that it has been difficult to fabricate, machine, and assembly parts of such a rotation limiting device of the related art. 
     DISCLOSURE 
     Technical Problem 
     Accordingly, embodiments of the present disclosure have been made in consideration of the above-described problems occurring in the related art and may provide a steer-by-wire steering apparatus limiting driver&#39;s operation of the steering wheel within a minimum angle of rotation so as to improve driver&#39;s feeling of steering and prevent a clock spring disposed on the steering wheel from being damaged, wherein parts of the steering apparatus may be more easily fabricated and machined and more simply fitted together, and the interference of the parts with surrounding components may be reduced, so that the steer-by-wire steering apparatus may be designed in a variety of structures and advantageous for packaging. 
     Technical Solution 
     According to embodiments of the present disclosure, provided is a steer-by-wire steering apparatus including: a leadscrew coupled to a steering shaft and including a first screw provided on an outer circumferential portion thereof; a first stopper and a second stopper coupled to one axial end portion and the other axial end portion of the leadscrew, respectively; a nut positioned between the first stopper and the second stopper, coupled to the leadscrew, and including a second screw provided on an inner circumferential portion thereof to engage with the first screw; and a hollow guide ring provided between a housing and the nut and supported on the nut in a circumferential direction. First insert recesses may be provided in an inner circumferential portion of the housing, and second insert recesses corresponding to the first insert recesses may be provided in an outer circumferential portion of the guide ring. The guide ring may be coupled to the housing by insert members inserted into the first insert recesses and the second insert recesses. 
     Advantageous Effects 
     According to embodiments of the present disclosure, the steer-by-wire steering apparatus can limit the driver&#39;s operation of the steering wheel within the minimum angle of rotation so as to improve driver&#39;s feeling of steering and prevent a clock spring disposed on the steering wheel from being damaged. Parts of the steering apparatus can be more easily fabricated and machined and more simply fitted together, and the interference of the parts with surrounding components can be reduced. The steer-by-wire steering apparatus can be designed in a variety of structures and advantageous for packaging. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is an exploded perspective view of a part of a steer-by-wire steering apparatus according to embodiments of the present disclosure; 
         FIG. 2  is an exploded perspective view of a part of FIG.  1 ; 
         FIG. 3  is a perspective view of an assembled position of  FIG. 1 ; 
         FIG. 4  is a front view of the assembled position of  FIG. 2 ; 
         FIG. 5  is a cross-sectional view of the steer-by-wire steering apparatus according to embodiments of the present disclosure; and 
         FIGS. 6 and 7  are cross-sectional views illustrating operation states of  FIG. 5 . 
     
    
    
     BEST MODE 
     In the following description of examples or embodiments of the present disclosure, reference will be made to the accompanying drawings in which it is shown by way of illustration specific examples or embodiments that can be implemented, and in which the same reference numerals and signs can be used to designate the same or like components even when they are shown in different accompanying drawings from one another. Further, in the following description of examples or embodiments of the present disclosure, detailed descriptions of well-known functions and components incorporated herein will be omitted when it is determined that the description may make the subject matter in some embodiments of the present disclosure rather unclear. The terms such as “including”, “having”, “containing”, “constituting” “make up of”, and “formed of” used herein are generally intended to allow other components to be added unless the terms are used with the term “only”. As used herein, singular forms are intended to include plural forms unless the context clearly indicates otherwise. 
     Terms, such as “first”, “second”, “A”, “B”, “(A)”, or “(B)” may be used herein to describe elements of the disclosure. Each of these terms is not used to define essence, order, sequence, or number of elements etc., but is used merely to distinguish the corresponding element from other elements. 
     When it is mentioned that a first element “is connected or coupled to”, “contacts or overlaps” etc. a second element, it should be interpreted that, not only can the first element “be directly connected or coupled to” or “directly contact or overlap” the second element, but a third element can also be “interposed” between the first and second elements, or the first and second elements can “be connected or coupled to”, “contact or overlap”, etc. each other via a fourth element. Here, the second element may be included in at least one of two or more elements that “are connected or coupled to”, “contact or overlap”, etc. each other. 
     When time relative terms, such as “after,” “subsequent to,” “next,” “before,” and the like, are used to describe processes or operations of elements or configurations, or flows or steps in operating, processing, manufacturing methods, these terms may be used to describe non-consecutive or non-sequential processes or operations unless the term “directly” or “immediately” is used together. 
     In addition, when any dimensions, relative sizes etc. are mentioned, it should be considered that numerical values for elements or features, or corresponding information (e.g., level, range, etc.) include a tolerance or error range that may be caused by various factors (e.g., process factors, internal or external impact, noise, etc.) even when a relevant description is not specified. Further, the term “may” fully encompasses all the meanings of the term “can”. 
       FIG. 1  is an exploded perspective view of a part of a steer-by-wire steering apparatus according to embodiments of the present disclosure,  FIG. 2  is an exploded perspective view of a part of  FIG. 1 ,  FIG. 3  is a front view of an assembled position of  FIG. 1 ,  FIG. 4  is a perspective view of the assembled position of  FIG. 2 ,  FIG. 5  is a cross-sectional view of the steer-by-wire steering apparatus according to embodiments of the present disclosure, and  FIGS. 6 and 7  are cross-sectional views illustrating operation states of  FIG. 5 . 
     The steer-by-wire steering apparatus  100  according to embodiments of the present disclosure includes: a leadscrew  134  coupled to a steering shaft  120  and having a first screw  201  provided on the outer circumferential portion thereof; a first stopper  131  coupled to one axial end portion of the leadscrew  134 ; a second stopper  133  coupled to the other axial end portion of the leadscrew  134 ; a nut  132  positioned between the first stopper  131  and the second stopper  133 , coupled to the leadscrew  134 , and having a second screw  202  provided on the inner circumferential portion thereof to engage with the first screw  201 ; and a hollow guide ring  140  provided between the housing  110  and the nut  132  and supported on the nut  132  in a circumferential direction. 
     Referring to  FIGS. 1 and 2 , a stopper assembly  130  includes the first stopper  131 , the nut  132 , the second stopper  133 , and the leadscrew  134 , and is coupled to the steering shaft  120 . 
     The leadscrew  134  rotates together with steering shaft  120 , and has the first screw  201  provided on the outer circumferential portion thereof. The nut  132  has the second screw  202  provided on the inner circumferential portion thereof, such that the first screw  201  engages with the second screw  202 , and the leadscrew  134  is coupled to the nut  132 . 
     The first stopper  131  is coupled to one axial end portion of the leadscrew  134 , and the second stopper  133  is coupled to the other axial end portion of the leadscrew  134 . That is, the nut  132  is provided between the first stopper  131  and the second stopper  133 . 
     An embodiment in which the first stopper  131  is provided on a side directed toward the steering wheel of the leadscrew  134  and the second stopper  133  is provided on the opposite side is illustrated in the drawings. A configuration having the opposite arrangement is also possible. 
     The guide ring  140  is provided as a hollow structure, between the housing  110  and the nut  132 . In other words, the stopper assembly  130  is provided inside the guide ring  140 . 
     Since the guide ring  140  is supported on the nut  132  in the circumferential direction, when the steering shaft  120  and the leadscrew  134  are rotated by the steering wheel operation of a driver, the nut  132  is slid in the axial direction while not being rotated. 
     A first serration  121  is provided on the outer circumferential portion of the steering shaft  120 , and a second serration  135  is provided on the inner circumferential portion of the leadscrew  134 . The leadscrew  134  may be axially fixed by a lock nut  511  coupled to the steering shaft  120 . 
     That is, the first serration  121  and the second serration  135  engage with each other. When the driver operates the steering wheel, the leadscrew  134  rotates together with steering shaft  120 . Since and the nut  132  is supported on the guide ring  140  in the circumferential direction while the rotation of the nut  132  is limited, the nut  132  is axially slid by the first screw  201  and the second screw  202 . 
     Meanwhile, each of the first screw  201  and the second screw  202  is implemented as a triangular screw, such that the threads may be more easily and precisely machined. 
     In general, the thread may have the shape of a rectangle, a trapezoid, a triangle, or the like. The rectangular or trapezoidal thread is widely used for power transmission. However, it is problematic in that the rectangular or trapezoidal thread is difficult to precisely machine compared to the triangular thread. 
     That is, since the nut  132  axially slides in response to the rotation of the leadscrew  134  in order to limit the rotation of the steering wheel within a maximum angle of rotation rather than transmitting power, it is possible to more easily and precisely machine the first screw  201  and the second screw  202  when each of the first screw  201  and the second screw  202  is implemented as a triangular thread instead of being implemented as a rectangular or trapezoidal thread (see  FIGS. 5 and 7 ). 
     Next, the first stopper  131  and the second stopper  133  are coupled to the leadscrew  134  to rotate therewith. When the driver&#39;s operation of the steering wheel reaches the maximum angle of rotation as will be described later, the first stopper  131  may be supported on the nut  132 , axially slid to one side, in the circumferential direction, or the second stopper  133  may be supported on the nut  132 , axially slid to the other side, in the circumferential direction. 
     Since the rotation of the nut  132  is limited by the guide ring  140  as described above, as the first stopper  131  or the second stopper  133  is supported on the nut  132  in the circumferential direction, the rotation of the leadscrew  134  to which the first stopper  131  and the second stopper  133  are coupled is limited. Consequently, the driver can be prevented from operating the steering wheel beyond the maximum angle of rotation. 
     Since the driver is mechanically prevented from operating the steering wheel beyond the maximum angle of rotation by the stopper assembly  130  and the guide ring  140 , a reaction force motor generating the feeling of steering in response to friction, bumping, or the like of the wheels on the road by transferring torque to the steering shaft using a nut pulley  510 , a belt  502 , and the like is not required to have enough power to cancel the steering torque of the driver at the maximum angle of rotation of the steering wheel. Thus, the size of the reaction force motor may be reduced, which is advantageous in terms of weight, cost, and packaging. 
     In addition, as the function of a vehicle is expanding, not only an airbag but also wiring for controlling a variety of functions is disposed inside the steering wheel. In general, such wiring is provided in the shape of clock springs. Such clock springs are wound or unwound when the driver operates the steering wheel. Limiting the angle of rotation of the steering wheel within the maximum angle of rotation can prevent the angle of rotation of the steering wheel from being excessively great and thus the clock springs from being damaged thereby. 
     In addition, since the guide ring  140  is supported on the inner circumferential portion of the housing  110  and the stopper assembly  130  is provided inside the guide ring  140 , axially fitting the guide ring  140  and the stopper assembly  130  together may be completed within the housing  110 , such that neither the guide ring  140  nor the stopper assembly  130  protrudes from the housing  110  so as to reduce interference with surrounding components. Accordingly, the steering apparatus can be designed in a variety of structures. 
     In addition, since the guide ring  140  has a hollow shape, the guide ring  140  may be simply fabricated by sintering and forging. 
     The guide ring  140  may be coupled to the housing  110  by insert members  150 . That is, first insert recesses  111  are provided in the inner circumferential portion of the housing  110 , and second insert recesses  141  corresponding to the first insert recesses  111  are provided in the outer circumferential portion of the guide ring  140 . Thus, the insert members  150  may be inserted into the first insert recesses  111  and the second insert recesses  141 . 
     The first insert recesses  111  and the second insert recesses  141  are axially provided. The guide ring  140  is supported on the inner circumferential portion of the housing  110  such that the first insert recesses  111  and the second insert recesses  141  face each other. The insert members  150  are inserted into the first insert recesses  111  and the second insert recesses  141 . Thus, the guide ring  140  may be easily inserted into the housing  110 . 
     Two first insert recesses  111  and two second insert recesses  141  may be provided. As the insert members  150  are inserted into the first insert recesses  111  and the second insert recesses  141 , the guide ring  140  is fixed to the housing  110  in the circumferential direction so that the rotation of the guide ring  140  is limited. 
     Although an embodiment in which each of the first insert recesses  111  and the second insert recesses  141  is in the shape of a rectangular recess and each of the insert members  150  is provided as a rectangular column is illustrated in the figures, the present disclosure is not necessarily limited thereto. 
     In order to limit the rotation of the nut  132  so that the nut  132  slides only in the axial direction as described above, first protrusions  142  may be provided on the inner circumferential portion of the guide ring  140 , and second protrusions  231  may be provided on the outer circumferential portion of the nut  132  to be supported on the first protrusion  142 . 
     Referring to  FIG. 3 , the stopper assembly  130  and the guide ring  140  are fitted to each other, and the first protrusions  142  and the second protrusions  231  are supported on each other in the circumferential direction. Thus, during rotation of the leadscrew  134 , the nut  132  slides only in the axial direction. 
     The second protrusions  231  are provided on both sides of the first protrusions  142  in the circumferential direction. Thus, rotation of the nut  132  to one side or the other side in the circumferential direction is limited. 
     In addition, two or more first protrusions  142  may be provided. As illustrated in the figures, the first protrusions  142  may be provided on the upper and lower portions in the figures, and the second protrusions  231  may be provided on both sides of the first protrusions  142 . 
     As a plurality of first protrusions  142  and a plurality of second protrusions  231  are provided such that the first protrusions  142  are in surface contact with the second protrusions  231 , the support areas of the first protrusions  142  and the second protrusions  231  may be increased to prevent stress concentration. Thus, this configuration is advantageous in terms of strength. 
     In addition, elastic members  143  may be coupled to the first protrusions  142  and supported on the second protrusions  231  in order to reduce friction and noise occurring between the first protrusions  142  and the second protrusions  231  when the nut  132  slides in the axial direction. 
     Each of the elastic members  143  may be implemented as an O-ring that is elastically deformable. Each of the O-rings may be coupled to a side surface of the corresponding first protrusion  142 , and be provided between the first protrusion  142  and the second protrusions  231 . 
     Meanwhile, as described above, coupling holes  211  into which the leadscrew  134  is inserted are provided in the first stopper  131  and the second stopper  133  provided on both sides of the nut  132  in the axial direction to limit the driver&#39;s operation of the steering wheel within the maximum angle of rotation, such that both ends of the leadscrew  134  are inserted into the coupling holes  211 . 
     In addition, first coupling recesses  212  are provided in the inner circumferential portions of the first stopper  131  and the second stopper  133 , second coupling recesses  213  corresponding to the first coupling recesses  212  are provided on one and the other axial end portions of the leadscrew  134 . Coupling members  214  may be inserted into the first coupling recesses  212  and the second coupling recesses  213 . 
     That is, the first coupling recesses  212  and the second coupling recesses  213  are provided in the axial direction. Both end portions of the leadscrew  134  are inserted into the first stopper  131  and the second stopper  133  such that the first coupling recesses  212  and the second coupling recesses  213  face each other. The coupling members  214  are inserted into the first coupling recesses  212  and the second coupling recesses  213 . The first stopper  131  and the second stopper  133  may be fitted to the leadscrew  134  in a simple manner (see  FIG. 4 ). 
     Here, the nut  132  should be fitted to the leadscrew  134  before the first stopper  131  and the second stopper  133  are fitted to each other. 
     Four first coupling recesses  212  and four second coupling recesses  213  may be provided. As the coupling members  214  are inserted into the first coupling recesses  212  and the second coupling recesses  213 , the first stopper  131  and the second stopper  133  are fixed to the leadscrew  134  in the circumferential direction so as to rotate together with the leadscrew  134 . 
     Although an embodiment in which each of the first coupling recesses  212  and the second coupling recesses  213  has a semicircular shape and each of the coupling members  214  has a cylindrical shape is illustrated in the figures, the present disclosure is not necessarily limited thereto. 
     In addition, first to fourth support portions  221 ,  222 ,  223 , and  224  may be provided on the nut  132 , the first stopper  131 , and the second stopper  133 , such that the first stopper  131  or the second stopper  133  is supported on the nut  132  in the circumferential direction when the operator&#39; operation of the steering wheel reaches the maximum angle of rotation. 
       FIG. 5  illustrates a state in which the steering wheel is not rotated, in which the nut  132  is positioned at the center between the first stopper  131  and the second stopper  133 . 
       FIG. 6  illustrates a state in which the nut  132  has slid to one side in the axial direction to be supported on the first stopper  131  as the driver operates the steering wheel. 
     That is, the first support portion  221  is provided on one side portion of the nut  132  to protrude while being circumferentially inclined, and the second support portion  222  is provided on the other side portion of the nut  132  to protrude while being circumferentially inclined (see  FIG. 2 ). When the nut  132  slides to one side in the axial direction, the first support portion  221  and the second support portion  222  may be supported, and the driver&#39;s operation of the steering wheel may be limited within the maximum angle of rotation. 
       FIG. 7  illustrates a state in which the nut  132  has slid to the other side in the axial direction to be supported on the second stopper  133  in response as the driver operates the steering wheel in the opposite direction. 
     That is, the third support portion  223  is provided on the other side portion of the nut  132  to protrude while being circumferentially inclined, and the fourth support portion  224  is provided on one side portion of the second stopper  133  to protrude while being circumferentially inclined (see  FIG. 2 ). When the nut  132  slides to the opposite side in the axial direction, the third support portion  223  and the fourth support portion  224  may be supported, and the driver&#39;s operation of the steering wheel may be limited within the maximum angle of rotation. 
     Each of the first to fourth support portions  221 ,  222 ,  223 , and  224  includes a slope surface circumferentially inclined and a vertical surface parallel to the axial direction. The rotation of the steering shaft  120  is limited while the vertical surface of the first support portion  221  and the vertical surface of the second support portion  222  are supported or the vertical surface of the third support portion  223  and the vertical surface of the fourth support portion  224  are supported. Consequently, the driver&#39;s operation of the steering wheel beyond the maximum angle of rotation is prevented. 
     According to the steer-by-wire steering apparatus having the above-described configuration, the driver&#39;s operation of the steering wheel can be limited within the minimum angle of rotation so as to improve driver&#39;s feeling of steering and prevent a clock spring disposed on the steering wheel from being damaged. Parts of the steering apparatus can be more easily fabricated and machined and more simply fitted together, and the interference of the parts with surrounding components can be reduced. The steer-by-wire steering apparatus can be designed in a variety of structures and advantageous for packaging. 
     The above description has been presented to enable any person skilled in the art to make and use the technical idea of the present 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 readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. The above description and the accompanying drawings provide an example of the technical idea of the present disclosure for illustrative purposes only. That is, the disclosed embodiments are intended to illustrate the scope of the technical idea of the present disclosure. Thus, the scope of the present disclosure is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims. The scope of protection of the present disclosure should be construed based on the following claims, and all technical ideas within the scope of equivalents thereof should be construed as being included within the scope of the present disclosure. 
     CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims under 35 U.S.C. § 119(a) the benefit of priority to Korean Patent Application No. 10-2019-0073267, filed on Jun. 20, 2019, which is hereby incorporated by reference for all purposes as if fully set forth herein. In addition, when this application claims priority in countries other than the U.S.A. on the same basis, the entire content of which is hereby incorporated by reference.