Patent Publication Number: US-2020290397-A1

Title: Vehicle wheel disc and vehicle disc wheel

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicle wheel disc and a disc wheel provided with the vehicle wheel disc. 
     BACKGROUND ART 
     In recent years, vehicles equipped with Electronic Stability Control (ESC) for stabilizing vehicle attitude during turning have become popular. In vehicles equipped with ESC, for example, when a driver causes a vehicle to make a sharp turn to urgently avoid an obstacle, the ESC operates so as to prevent skidding. At this point of operation, a large lateral force is generated in the wheel discs. Accordingly, wheel discs for use in a vehicle equipped with ESC are required to have higher rigidity than wheel discs for use in a conventional vehicle which are not equipped with ESC. 
     A technique for increasing rigidity of a vehicle wheel disc has been proposed. 
     For example, Patent Document 1 discloses a vehicle wheel disc having window forming portions. In the vehicle wheel disc of Patent Document 1, an outer side surface of the window forming portion in the radial direction of the disc is formed of a flat surface which is orthogonal to the radial direction of the disc. There is a description in Patent Document 1 that the above-mentioned configuration can prevent the window forming portion from being easily deformed when a force is applied to a rim from a tire of a vehicle. 
     LIST OF PRIOR ART DOCUMENTS 
     Patent Document 
     Patent Document 1: JP2017-52342A 
     SUMMARY OF INVENTION 
     Technical Problem 
     Only with the existing techniques, however, it is not sufficient to meet the demand for enhancing rigidity of a wheel disc. Accordingly, to ensure rigidity required for a wheel disc in a vehicle equipped with the ESC, it has been necessary to use a high strength material as a material for the wheel disc, or to increase the sheet thickness of the wheel disc. However, using a high, strength material poses a problem of increased manufacturing costs for the wheel disc, whereas increasing the sheet thickness of the wheel disc poses a problem of increased weight of the wheel disc. 
     In view of the above, an object of the present invention is to provide a vehicle wheel disc having high rigidity and a vehicle disc wheel provided with the vehicle wheel disc. 
     Solution to Problem 
     In general, a wheel disc is fixed to a hub of an axle in a vehicle. Specifically, bolts provided to the hub are inserted through bolt holes formed in the wheel disc and, thereafter, nuts are threadedly engaged with the bolts so that the wheel disc is fixed to the hub. 
     With respect to the wheel disc which is fixed to the hub as described above, the inventors of the present invention have made extensive studies in detail on a force which acts on the wheel disc from the axle, and a phenomenon which occurs in the wheel disc when the force is applied to the wheel disc. As a result, it is found that when a large force acts on the wheel disc from the axle, portions of the wheel disc which are fixed to the hub (more specifically, portions which are fastened by the nuts) are plastically deformed, thus increasing a possibility of occurrence of buckling on the wheel disc. 
     The present invention has been made based on the above-mentioned findings, and a vehicle wheel disc and a vehicle disc wheel described below are the gist of the present invention. 
     (1) A vehicle wheel disc to be mounted on a hub of an axle by a plurality of bolts provided to the hub and a plurality of nuts to be threadedly engaged with the plurality of bolts, 
     the vehicle wheel disc including a mounting portion provided with a plurality of bolt holes through which the plurality of bolts are to be inserted, the mounting portion being adapted to be mounted on the hub by being fastened by the plurality of bolts inserted through the plurality of bolt holes and the plurality of nuts, wherein 
     the mounting portion includes a flat plate portion having a pressing surface to be pressed against the hub, and a plurality of nut support portions protruding from the flat plate portion to a side opposite to the pressing surface in an axial direction of the vehicle wheel disc, and having an annular shape as viewed from the axial direction, 
     each of the plurality of bolt holes penetrates the nut support portion in the axial direction, and 
     each of the plurality of nut support portions includes a bulging portion curving to bulge outward in a radial direction of the nut support portion, and at least one protruding portion disposed adjacent to the bulging portion in a circumferential direction of the nut support portion, and protruding inward in the radial direction or outward in the radial direction of the nut support portion with respect to the bulging portion. 
     (2) The vehicle wheel disc according to the above-mentioned (1), wherein in a case where, as viewed from the axial direction, a straight line passing through a center of the vehicle wheel disc and a center of the bolt hole is assumed as a first imaginary line, and the nut support portion is divided into two regions by the first imaginary line, the protruding portion is provided to each of the two regions. 
     (3) The vehicle wheel disc according to the above-mentioned (1), wherein in a case where, as viewed from the axial direction, a straight line passing through a center of the vehicle wheel disc and a center of the bolt hole is assumed as a first imaginary line, a straight line passing through the center of the bolt hole and extending in a direction perpendicular to the first imaginary line is assumed as a second imaginary line, and the nut support portion is divided into two regions by the second imaginary line, the protruding portion is provided to each of the two regions. 
     (4) The vehicle wheel disc according to the above-mentioned (1), wherein in a case where, as viewed from the axial direction, a straight line passing through a center of the vehicle wheel disc and a center of the bolt hole is assumed as a first imaginary line, a straight line passing through the center of the bolt hole and extending in a direction perpendicular to the first imaginary line is assumed as a second imaginary line, and the nut support portion is divided into four regions by the first imaginary line and the second imaginary line, the protruding portion is provided to each of the four regions. 
     (5) A vehicle disc wheel including: a rim having a cylindrical shape; and the vehicle wheel disc according to any one of the above-mentioned (1) to (4) which is joined to the rim. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to obtain a vehicle wheel disc having high rigidity and a vehicle disc wheel provided with the vehicle wheel disc. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view showing a vehicle disc wheel according to one embodiment of the present invention. 
         FIG. 2  is an end view taken along a line A-A in  FIG. 1 . 
         FIG. 3  is a schematic cross-sectional view of a nut support portion. 
         FIG. 4  is a schematic perspective view showing the nut support portion. 
         FIG. 5  is a view for describing positions where protruding portions are formed. 
         FIG. 6  is a view for describing positions where protruding portions are formed. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a vehicle wheel disc and a vehicle disc wheel according to an embodiment of the present invention will be described with reference to drawings. 
     (Configuration of Vehicle Disc Wheel) 
       FIG. 1  is a plan view showing a vehicle disc wheel  10  (hereinafter, abbreviated as “wheel  10 ”) according to one embodiment of the present invention, and  FIG. 2  is a schematic end view of a portion which corresponds to a line A-A in  FIG. 1 . In  FIG. 2 , the axis of a vehicle wheel disc  14  described later is indicated by a two-dot chain line. 
     Referring to  FIG. 1  and  FIG. 2 , the wheel  10  includes a rim  12  having a cylindrical shape, and the vehicle wheel disc  14  (hereinafter, abbreviated as “disc  14 ”) according to one embodiment of the present invention. Various metal materials and resin materials may be used as materials for the rim  12  and the disc  14 . Steel (hot-rolled steel sheet, for example), aluminum, an aluminum alloy or the like may be used as the metal material, for example. 
     The rim  12  and the disc  14  are welded in a state where the disc  14  is fitted in the rim  12 , thus being joined with each other. Note that any of various known configurations of the rim can be adopted as the configuration of the rim  12  so that the detailed description will be omitted. 
     Although the detailed description will be omitted, in producing the disc  14 , for example, first, a metal sheet obtained from a material coil is cut into a predetermined size. Thereafter, the metal sheet which is cut into the predetermined size is punched, thus obtaining a blank having a predetermined shape. Further, predetermined working, such as drawing and punching, is performed on the obtained blank, thus obtaining the disc  14 . 
     The disc  14  has a substantially disc shape as a whole. A hub hole  16  is formed at the center portion of the disc  14 . The hub hole  16  has a circular shape as viewed from the axial direction of the disc  14 . The disc  14  includes a mounting portion  18 , a hat portion  20  and a flange portion  22  which are provided in this order from the hub hole  16  toward the outside in the radial direction of the hub hole  16 . 
     The mounting portion  18  is fastened by a plurality of bolts provided to a hub of an axle of a vehicle not shown in the drawing and a plurality of nuts to be threadedly engaged with the plurality of bolts, thus being mounted on the hub of the axle. The detail of the mounting portion  18  will be described later. Note that the mode of mounting the mounting portion  18  on the hub of the axle is substantially equal to the mode in a known wheel discs so that the detailed description will be omitted. 
     The hat portion  20  is formed to bulge from the mounting portion  18  in the axial direction of the disc  14 . The flange portion  22  has a cylindrical shape, and is welded to the rim  12 . Note that any of various known configurations of the hat portion and the flange portion can be adopted as the configurations of the hat portion  20  and the flange portion  22  so that the detailed description will be omitted. 
     Hereinafter, the mounting portion  18  will be described in detail. 
     The mounting portion  18  includes a flat plate portion  24  and a plurality of (four in this embodiment) nut support portions  26 . Referring to  FIG. 2 , the flat plate portion  24  includes a pressing surface  24   a . The pressing surface  24   a  is a surface which is pressed against the hub when the mounting portion  18  is mounted on the hub of the vehicle not shown in the drawing. 
     Referring to  FIG. 1 , the plurality of nut support portions  26  are arranged equidistantly in the circumferential direction of the disc  14 . Each of the plurality of nut support portions  26  has an annular shape as viewed from the axial direction of the disc  14 . Referring to  FIG. 2 , the nut support portion  26  protrudes from the flat plate portion  24  to the side opposite to the pressing surface  24   a  in the axial direction of the disc  14 . 
       FIG. 3  is a schematic cross-sectional view of the nut support portion  26  (a portion which corresponds to a line B-B in  FIG. 1 ), and  FIG. 4  is a schematic perspective view showing the nut support portion  26 . 
     Referring to  FIG. 1  to  FIG. 4 , a bolt hole  28  through which the bolt is inserted is formed at the center portion of each nut support portion  26 . The bolt hole  28  is formed to penetrate the nut support portion  26  in the axial direction of the disc  14 . Referring to  FIG. 3  and  FIG. 4 , a nut bearing surface  30  is formed at the center portion of the nut support portion  26  to communicate with the bolt hole  28 . In this embodiment, the nut bearing surface  30  has a tapered shape. In this embodiment, the nut bearing surface  30  is formed such that the diameter of the nut bearing surface  30  increases as the distance from the pressing surface  24   a  increases in the axial direction of the disc  14 . 
     In this embodiment, the plurality of bolts provided to the hub of the axle are inserted through the plurality of bolt holes  28  formed in the mounting portion  18 , and the nuts are threadedly engaged with the respective bolts so that the disc  14  is mounted on the hub. The nut bearing surface  30  is a surface which supports the nut threadedly engaged with the bolt. Note that the shape of the nut bearing surface is not limited to the above-mentioned example, and any of various known shapes of the nut bearing surface may be adopted. 
     Referring to  FIG. 3  and  FIG. 4 , each nut support portion  26  includes a raised portion  26   a , a plurality of bulging portions  26   b  and a plurality of protruding portions  26   c . The raised portion  26   a  is a portion which is raised from the flat plate portion  24  to the side opposite to the pressing surface  24   a  in the axial direction of the disc  14 , and has an annular shape as viewed from the axial direction of the disc  14 . The raised portion  26   a  curves to bulge inward in the radial direction of the nut support portion  26 . In this embodiment, the raised portion  26   a  is formed to extend inward in the radial direction of the nut support portion  26 , and to project in a direction approaching the pressing surface  24   a  in the axial direction of the disc  14 . 
     The plurality of (four in this embodiment) bulging portions  26   b  and the plurality of (four in this embodiment) protruding portions  26   c  are respectively provided between the raised portion  26   a  and the nut bearing surface  30 . In this embodiment, the plurality of bulging portions  26   b  and the plurality of protruding portions  26   c  are provided such that the bulging portion  26   b  and the protruding portion  26   c  are alternately arranged in the circumferential direction of the nut support portion  26 . 
     Referring to  FIG. 4 , as viewed from the axial direction of the disc  14 , each bulging portion  26   b  has an arc shape. Referring to  FIG. 3  and  FIG. 4 , the bulging portion  26   b  curves to bulge outward in the radial direction of the nut support portion  26 . In this embodiment, the bulging portion  26   b  is formed to extend outward in the radial direction of the nut support portion  26 , and to project in a direction away from the pressing surface  24   a  in the axial direction of the disc  14 . 
     The protruding portion  26   c  is disposed adjacent to the bulging portions  26   b  in the circumferential direction of the nut support portion  26 . The protruding portion  26   c  protrudes inward in the radial direction of the nut support portion  26  with respect to the bulging portion  26   b . In this embodiment, the protruding portion  26   c  extends inward in the radial direction of the nut support portion  26 , and protrudes in a direction approaching the pressing surface  24   a  in the axial direction of the disc  14 . 
     Referring to  FIG. 3 , in this embodiment, an outer surface  51  (a surface disposed outward in the radial direction of the nut support portion  26 ) of the protruding portion  26   c  is recessed toward the inside of the nut support portion  26  with respect to an outer surface  41  (a surface disposed outward in the radial direction of the nut support portion  26 ) of the bulging portion  26   b . Further, an inner surface  52  (a surface disposed inward in the radial direction of the nut support portion  26 ) of the protruding portion  26   c  protrudes toward the inside of the nut support portion  26  with respect to an inner surface  42  (a surface disposed inward in the radial direction of the nut support portion  26 ) of the bulging portion  26   b.    
     (Advantageous Effects of this Embodiment) 
     As has been described above, in the disc  14  according to this embodiment, the protruding portions  26   c  are provided to each nut support portion  26 . The protruding portions  26   c  function as reinforcing ribs when a lateral force (a force in the axial direction of the disc  14 ) acts on the nut support portion  26 . With such a configuration, even when a large force acts on the disc  14  from the axle, it is possible to suppress plastic deformation of the nut support portion  26 . As a result, it is possible to suppress the occurrence of buckling on the disc  14 . In other words, in the disc  14  according to this embodiment, rigidity of the disc  14  can be increased without changing a material from a material used for a conventional disc or changing a sheet thickness. Therefore, according to this embodiment, rigidity of the disc  14  can be increased while an increase in manufacturing costs for the disc  14  and an increase in weight are suppressed. 
     (Positions of Protruding Portions) 
     Hereinafter, positions where the protruding portions are formed in the nut support portion will be described.  FIG. 5  and  FIG. 6  are views for describing the positions where the protruding portions are formed.  FIG. 5( a )  is a view showing the mounting portion  18  in the above-mentioned embodiment, and  FIG. 5( b ) ,  FIG. 6( a )  and  FIG. 6( b )  are views showing modifications of the mounting portion  18 . In  FIG. 5 , each imaginary straight line passing through the center of the disc  14  and the centers of the bolt holes  28  as viewed from the axial direction of the disc  14  is assumed as a first imaginary line L 1 , and is indicated by a chain line. Further, in  FIG. 5  and  FIG. 6 , each imaginary straight line passing through the center of the bolt hole  28  and extending in a direction perpendicular to the first imaginary line L 1  (see  FIG. 5 ) as viewed from the axial direction of the disc  14  is assumed as a second imaginary line L 2 , and is indicated by a two-dot chain line. The first imaginary lines L 1  are straight lines extending in a direction perpendicular to the axial direction of the disc  14 . Note that, in  FIG. 6 , the first imaginary lines L 1  are omitted in the drawing to prevent the drawing from becoming complicated. 
     Referring to  FIG. 5( a ) , in the above-mentioned embodiment, in the case where the nut support portion  26  is divided into four regions by the first imaginary line L 1  and the second imaginary line L 2  as viewed from the axial direction of the disc  14 , the protruding portion  26   c  is provided in each of the four regions. However, the positions where the protruding portions  26   c  are formed are not limited to the above-mentioned example. For example, in each nut support portion  26 , two protruding portions  26   c  may be formed on the first imaginary line L 1 , and two protruding portions  26   c  may be formed on the second imaginary line L 2 . That is, the four protruding portions may be formed at positions displaced from the positions of the four protruding portions  26   c  shown in  FIG. 5( a )  by 45° in the circumferential direction of the nut support portion  26 . 
     Further, for example, as shown in  FIG. 5( b ) , in the case where the nut support portion  26  is divided into two regions by the first imaginary line L 1  as viewed from the axial direction of the disc  14 , the protruding portion  26   c  may be provided to each of the two regions. Positions where the protruding portions  26   c  are formed in the two regions are not particularly limited. For example, the protruding portion  26   c  in one region and the protruding portion  26   c  in the other region are disposed at positions line-symmetrical to each other with respect to the first imaginary line L 1 . Further, although the number of protruding portions  26   c  provided in each of the two regions is not particularly limited, for example, the same number of protruding portions  26   c  are provided to each of one region and the other region. 
     Further, for example, as shown in  FIG. 6( a ) , in the case where the nut support portion  26  is divided into two regions by the second imaginary line L 2  as viewed from the axial direction of the disc  14 , the protruding portion may be provided to each of the two regions. The number of protruding portions  26   c  provided to each of the two regions is not particularly limited. However, for example, as shown in  FIG. 6( b ) , of the two regions, the number of protruding portions  26   c  in the region disposed outward in the radial direction of the disc  14  may be larger than the number of protruding portions  26   c  in the region disposed inward in the radial direction of the disc  14 . Alternatively, although not shown in the drawing, of the two regions, the number of protruding portions  26   c  in the region disposed inward in the radial direction of the disc  14  may be larger than the number of protruding portions  26   e  in the region disposed outward in the radial direction of the disc  14 . 
     Further, the number of protruding portions  26   c  provided to each nut support portion  26  is not limited to the above-mentioned example. For example, the number of protruding portions  26   c  provided to each nut support portion  26  may be one or may be five or more. For example, in the mounting portion  18  shown in  FIG. 6( a ) , one of the two protruding portions  26   c  provided to each nut support portion  26  may not be provided. 
     Further, in the above-mentioned embodiment, the case has been described where the protruding portion  26   c  protrudes inward in the radial direction of the nut support portion  26  with respect to the bulging portion  26   b . However, the shape of the protruding portion is not limited to the above-mentioned example. For example, the protruding portion may protrude outward in the radial direction of the nut support portion  26  with respect to the bulging portion  26   b . More specifically, for example, the protruding portion may extend outward in the radial direction of the nut support portion  26  with respect to the bulging portion  26   b , and may protrude in a direction away from the pressing surface  24   a  in the axial direction of the disc  14 . In this case, the nut support portion  26  is formed such that the outer surface of the protruding portion protrudes toward the outside of the nut support portion  26  with respect to the outer surface  41  of the bulging portion  26   b  (see  FIG. 3 ), and the inner surface of the protruding portion is recessed toward the outside of the nut support portion  26  with respect to the inner surface  42  of the bulging portion  26   b  (see  FIG. 3 ). Also in the case where the protruding portion is formed as described above, the substantially the same advantageous effects as the above-mentioned embodiment can be obtained. 
     In addition, each nut support portion  26  may be provided with the protruding portion which protrudes inward in the radial direction of the nut support portion  26  with respect to the bulging portion  26   b  and the protruding portion which protrudes outward in the radial direction of the nut support portion  26  with respect to the bulging portion  26   b.    
     Although the detailed description will be omitted, it is preferable that the protruding portion be provided at a position in the vicinity of a portion of the pressing surface  24   a  to be firmly pressed against the hub when the mounting portion  18  is mounted on the hub of the axle. 
     INDUSTRIAL APPLICABILITY 
     As has been described above, according to the present invention, it is possible to obtain a vehicle wheel disc having high rigidity and a vehicle disc wheel provided with the vehicle wheel disc. Therefore, the present invention is preferably used for a disc wheel of the vehicle. 
     REFERENCE SIGNS LIST 
     
         
           10  vehicle disc wheel 
           12  rim 
           14  vehicle wheel disc 
           16  hub hole 
           18  mounting portion 
           20  hat portion 
           22  flange portion 
           24  flat plate portion 
           24   a  pressing surface 
           26  nut support portion 
           26   a  raised portion 
           26   b  bulging portion 
           26   e  protruding portion 
           28  bolt hole 
           30  nut bearing surface 
           41 ,  51  outer surface 
           42 ,  52  inner surface