Vehicle wheel disc and vehicle disc wheel

A mounting portion of a disc includes a flat plate portion having a pressing surface to be pressed against a hub of an axle, 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 disc, and having an annular shape as viewed from the axial direction. A bolt hole is provided to penetrate the nut support portion in the axial direction. The nut support portion includes a bulging portion curving to bulge outward in a radial direction of the nut support portion, and a protruding portion disposed adjacent to the bulging portion in a circumferential direction of the nut support portion, and protruding inward in the radial direction of the nut support portion with respect to the bulging portion.

This application is a national phase of PCT/JP2018/036174 filed on Sep. 28, 2018.

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

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.

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.1is a plan view showing a vehicle disc wheel10(hereinafter, abbreviated as “wheel10”) according to one embodiment of the present invention, andFIG.2is a schematic end view of a portion which corresponds to a line A-A inFIG.1. InFIG.2, the axis of a vehicle wheel disc14described later is indicated by a two-dot chain line.

Referring toFIG.1andFIG.2, the wheel10includes a rim12having a cylindrical shape, and the vehicle wheel disc14(hereinafter, abbreviated as “disc14”) according to one embodiment of the present invention. Various metal materials and resin materials may be used as materials for the rim12and the disc14. Steel (hot-rolled steel sheet, for example), aluminum, an aluminum alloy or the like may be used as the metal material, for example.

The rim12and the disc14are welded in a state where the disc14is fitted in the rim12, thus being joined with each other. Note that any of various known configurations of the rim can be adopted as the configuration of the rim12so that the detailed description will be omitted.

Although the detailed description will be omitted, in producing the disc14, 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 disc14.

The disc14has a substantially disc shape as a whole. A hub hole16is formed at the center portion of the disc14. The hub hole16has a circular shape as viewed from the axial direction of the disc14. The disc14includes a mounting portion18, a hat portion20and a flange portion22which are provided in this order from the hub hole16toward the outside in the radial direction of the hub hole16.

The mounting portion18is 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 portion18will be described later. Note that the mode of mounting the mounting portion18on 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 portion20is formed to bulge from the mounting portion18in the axial direction of the disc14. The flange portion22has a cylindrical shape, and is welded to the rim12. Note that any of various known configurations of the hat portion and the flange portion can be adopted as the configurations of the hat portion20and the flange portion22so that the detailed description will be omitted.

Hereinafter, the mounting portion18will be described in detail.

The mounting portion18includes a flat plate portion24and a plurality of (four in this embodiment) nut support portions26. Referring toFIG.2, the flat plate portion24includes a pressing surface24a. The pressing surface24ais a surface which is pressed against the hub when the mounting portion18is mounted on the hub of the vehicle not shown in the drawing.

Referring toFIG.1, the plurality of nut support portions26are arranged equidistantly in the circumferential direction of the disc14. Each of the plurality of nut support portions26has an annular shape as viewed from the axial direction of the disc14. Referring toFIG.2, the nut support portion26protrudes from the flat plate portion24to the side opposite to the pressing surface24ain the axial direction of the disc14.

FIG.3is a schematic cross-sectional view of the nut support portion26(a portion which corresponds to a line B-B inFIG.1), andFIG.4is a schematic perspective view showing the nut support portion26.

Referring toFIG.1toFIG.4, a bolt hole28through which the bolt is inserted is formed at the center portion of each nut support portion26. The bolt hole28is formed to penetrate the nut support portion26in the axial direction of the disc14. Referring toFIG.3andFIG.4, a nut bearing surface30is formed at the center portion of the nut support portion26to communicate with the bolt hole28. In this embodiment, the nut bearing surface30has a tapered shape. In this embodiment, the nut bearing surface30is formed such that the diameter of the nut bearing surface30increases as the distance from the pressing surface24aincreases in the axial direction of the disc14.

In this embodiment, the plurality of bolts provided to the hub of the axle are inserted through the plurality of bolt holes28formed in the mounting portion18, and the nuts are threadedly engaged with the respective bolts so that the disc14is mounted on the hub. The nut bearing surface30is 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 toFIG.3andFIG.4, each nut support portion26includes a raised portion26a, a plurality of bulging portions26band a plurality of protruding portions26c. The raised portion26ais a portion which is raised from the flat plate portion24to the side opposite to the pressing surface24ain the axial direction of the disc14, and has an annular shape as viewed from the axial direction of the disc14. The raised portion26acurves to bulge inward in the radial direction of the nut support portion26. In this embodiment, the raised portion26ais formed to extend inward in the radial direction of the nut support portion26, and to project in a direction approaching the pressing surface24ain the axial direction of the disc14.

The plurality of (four in this embodiment) bulging portions26band the plurality of (four in this embodiment) protruding portions26care respectively provided between the raised portion26aand the nut bearing surface30. In this embodiment, the plurality of bulging portions26band the plurality of protruding portions26care provided such that the bulging portion26band the protruding portion26care alternately arranged in the circumferential direction of the nut support portion26.

Referring toFIG.4, as viewed from the axial direction of the disc14, each bulging portion26bhas an arc shape. Referring toFIG.3andFIG.4, the bulging portion26bcurves to bulge outward in the radial direction of the nut support portion26. In this embodiment, the bulging portion26bis formed to extend outward in the radial direction of the nut support portion26, and to project in a direction away from the pressing surface24ain the axial direction of the disc14.

The protruding portion26cis disposed adjacent to the bulging portions26bin the circumferential direction of the nut support portion26. The protruding portion26cprotrudes inward in the radial direction of the nut support portion26with respect to the bulging portion26b. In this embodiment, the protruding portion26cextends inward in the radial direction of the nut support portion26, and protrudes in a direction approaching the pressing surface24ain the axial direction of the disc14.

Referring toFIG.3, in this embodiment, an outer surface51(a surface disposed outward in the radial direction of the nut support portion26) of the protruding portion26cis recessed toward the inside of the nut support portion26with respect to an outer surface41(a surface disposed outward in the radial direction of the nut support portion26) of the bulging portion26b. Further, an inner surface52(a surface disposed inward in the radial direction of the nut support portion26) of the protruding portion26cprotrudes toward the inside of the nut support portion26with respect to an inner surface42(a surface disposed inward in the radial direction of the nut support portion26) of the bulging portion26b.

(Advantageous Effects of this Embodiment)

As has been described above, in the disc14according to this embodiment, the protruding portions26care provided to each nut support portion26. The protruding portions26cfunction as reinforcing ribs when a lateral force (a force in the axial direction of the disc14) acts on the nut support portion26. With such a configuration, even when a large force acts on the disc14from the axle, it is possible to suppress plastic deformation of the nut support portion26. As a result, it is possible to suppress the occurrence of buckling on the disc14. In other words, in the disc14according to this embodiment, rigidity of the disc14can 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 disc14can be increased while an increase in manufacturing costs for the disc14and an increase in weight are suppressed.

Hereinafter, positions where the protruding portions are formed in the nut support portion will be described.FIG.5andFIG.6are views for describing the positions where the protruding portions are formed.FIG.5(a)is a view showing the mounting portion18in the above-mentioned embodiment, andFIG.5(b),FIG.6(a)andFIG.6(b)are views showing modifications of the mounting portion18. InFIG.5, each imaginary straight line passing through the center of the disc14and the centers of the bolt holes28as viewed from the axial direction of the disc14is assumed as a first imaginary line L1, and is indicated by a chain line. Further, inFIG.5andFIG.6, each imaginary straight line passing through the center of the bolt hole28and extending in a direction perpendicular to the first imaginary line L1(seeFIG.5) as viewed from the axial direction of the disc14is assumed as a second imaginary line L2, and is indicated by a two-dot chain line. The first imaginary lines L1are straight lines extending in a direction perpendicular to the axial direction of the disc14. Note that, inFIG.6, the first imaginary lines L1are omitted in the drawing to prevent the drawing from becoming complicated.

Referring toFIG.5(a), in the above-mentioned embodiment, in the case where the nut support portion26is divided into four regions by the first imaginary line L1and the second imaginary line L2as viewed from the axial direction of the disc14, the protruding portion26cis provided in each of the four regions. However, the positions where the protruding portions26care formed are not limited to the above-mentioned example. For example, in each nut support portion26, two protruding portions26cmay be formed on the first imaginary line L1, and two protruding portions26cmay be formed on the second imaginary line L2. That is, the four protruding portions may be formed at positions displaced from the positions of the four protruding portions26cshown inFIG.5(a)by 45° in the circumferential direction of the nut support portion26.

Further, for example, as shown inFIG.5(b), in the case where the nut support portion26is divided into two regions by the first imaginary line L1as viewed from the axial direction of the disc14, the protruding portion26cmay be provided to each of the two regions. Positions where the protruding portions26care formed in the two regions are not particularly limited. For example, the protruding portion26cin one region and the protruding portion26cin the other region are disposed at positions line-symmetrical to each other with respect to the first imaginary line L1. Further, although the number of protruding portions26cprovided in each of the two regions is not particularly limited, for example, the same number of protruding portions26care provided to each of one region and the other region.

Further, for example, as shown inFIG.6(a), in the case where the nut support portion26is divided into two regions by the second imaginary line L2as viewed from the axial direction of the disc14, the protruding portion may be provided to each of the two regions. The number of protruding portions26cprovided to each of the two regions is not particularly limited. However, for example, as shown inFIG.6(b), of the two regions, the number of protruding portions26cin the region disposed outward in the radial direction of the disc14may be larger than the number of protruding portions26cin the region disposed inward in the radial direction of the disc14. Alternatively, although not shown in the drawing, of the two regions, the number of protruding portions26cin the region disposed inward in the radial direction of the disc14may be larger than the number of protruding portions26ein the region disposed outward in the radial direction of the disc14.

Further, the number of protruding portions26cprovided to each nut support portion26is not limited to the above-mentioned example. For example, the number of protruding portions26cprovided to each nut support portion26may be one or may be five or more. For example, in the mounting portion18shown inFIG.6(a), one of the two protruding portions26cprovided to each nut support portion26may not be provided.

Further, in the above-mentioned embodiment, the case has been described where the protruding portion26cprotrudes inward in the radial direction of the nut support portion26with respect to the bulging portion26b. 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 portion26with respect to the bulging portion26b. More specifically, for example, the protruding portion may extend outward in the radial direction of the nut support portion26with respect to the bulging portion26b, and may protrude in a direction away from the pressing surface24ain the axial direction of the disc14. In this case, the nut support portion26is formed such that the outer surface of the protruding portion protrudes toward the outside of the nut support portion26with respect to the outer surface41of the bulging portion26b(seeFIG.3), and the inner surface of the protruding portion is recessed toward the outside of the nut support portion26with respect to the inner surface42of the bulging portion26b(seeFIG.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 portion26may be provided with the protruding portion which protrudes inward in the radial direction of the nut support portion26with respect to the bulging portion26band the protruding portion which protrudes outward in the radial direction of the nut support portion26with respect to the bulging portion26b.

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 surface24ato be firmly pressed against the hub when the mounting portion18is 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