VEHICLE WHEEL DISC, VEHICLE WHEEL INCLUDING SUCH A WHEEL DISC AND METHOD FOR PRODUCING SUCH A WHEEL DISC AND VEHICLE WHEEL

BACKGROUND OF THE INVENTION

[0001] The present invention relates in general to a vehicle wheel disc and vehicle wheel and in particular to an improved wheel disc, vehicle wheel including such a wheel disc and method for producing such a wheel disc and vehicle wheel.

[0002] Wheels for automotive vehicles may be produced from light weight metals to reduce the weight of the wheels. For example, the vehicle wheels may be produced as a single cast component made from aluminum or alloys thereof. The weight of such wheels may be further reduced by removing mass or material from the wheels. A reduction in the weight of vehicle wheels may have the advantage of increasing the wheel's performance by reducing the unsprung mass of that component of the vehicle.

[0003] However, removing mass from the wheel also may reduce the stiffness and rigidity of the wheel. It is generally desirable to remove mass from the wheel without a significant reduction in stiffness and rigidity. In some situations, the aesthetic look of a reduced mass wheel may not appeal to consumers. Thus, it may be desirable to form the wheel such that a reduced mass is obtained while maintaining the aesthetic appeal of the wheel. SUMMARY OF THE INVENTION

[0004] The present invention relates to an improved wheel disc, vehicle wheel including such a wheel disc and method for producing such a wheel disc and vehicle wheel as illustrated and/or described herein.

[0005] According to one embodiment, the wheel disc may comprise, individually and/or in combination, one or more of the following features, elements, or advantages: a wheel disc includes a hub having bolt holes formed therein and defining a wheel axis, wherein the hub has a front face and a rear face defining a thickness therebetween, and wherein the hub has an outer edge and includes a perimeter wall extending axially outwardly from the front face at the outer edge. A plurality of spokes extends radially outward from the hub.

[0006] According to this embodiment, the perimeter wall forms a continuous loop about the outer edge.

[0007] According to this embodiment, the perimeter wall has a non-circular shape.

[0008] According to this embodiment, the perimeter wall defines a plurality of sides connected together at corners of the perimeter wall.

[0009] According to this embodiment, each of the sides has a curvilinear shape. [0010] According to this embodiment, each of the sides of the perimeter wall has a generally constant cross-sectional shape along the length of the side.

[0011] According to this embodiment, the cross-sectional shape is generally rectangular.

[0012] According to this embodiment, a spoke extends radially outwardly from each of the corners.

[0013] According to this embodiment, the perimeter wall has a pentagonal shape defining five sides and five corners.

[0014] According to this embodiment, each of the five sides has a curvilinear shape.

[0015] According to this embodiment, a spoke extends radially outwardly from each of the five corners.

[0016] According to this embodiment, the front face and the rear face of the hub are generally planar to one another.

[0017] According to this embodiment, a plurality of circumferentially spaced hub pockets is formed in the rear face of the hub.

[0018] According to this embodiment, the hub pockets are non-through holes such that each of the hub pockets defines a bottom surface formed in the hub. [0019] According to this embodiment, the bolt holes are circumferentially spaced about the front face of the hub.

[0020] According to this embodiment, at least one of the plurality of hub pockets is interspaced between two lug bolt receiving holes.

[0021] According to this embodiment, the perimeter wall defines a generally planar front surface.

[0022] According to this embodiment, the plurality of spokes defines a generally planar front surface that is co-planar with the front surface of the perimeter wall.

[0023] According to this embodiment, a portion of the bolt holes are formed into side walls of the perimeter wall.

[0024] According to this embodiment, the wheel disc is configured to be secured to a wheel rim by producing the wheel rim and the wheel disc by a forming process to produce a one-piece cast vehicle wheel or secured to a separately formed wheel rim by suitable means to produce a fabricated vehicle wheel, wherein the wheel disc and the wheel rim of the fabricated vehicle wheel are formed of similar or dissimilar materials.

[0025] According to this embodiment, each of the spokes has a cross- sectional width which varies along the radially extending length of the spoke. [0026] According to this embodiment, each of the spokes has a width which tapers from a proximal end adjacent the hub towards a distal end radially spaced outwardly from the hub.

[0027] Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Fig. 1 is a front elevational view of an embodiment of a vehicle wheel in accordance with the present invention.

[0029] Fig. 2 is a rear perspective view of the wheel of Fig. 1.

[0030] Fig. 3 is a side elevational view of the wheel of Fig. 1.

[0031] Fig. 4 is a front perspective view of the wheel of Fig. 1.

[0032] Fig. 5 is a rear perspective view of the wheel of Fig. 1.

[0033] Fig. 6 is a cross-sectional perspective view of the wheel taken along lines 6-6 of Fig. 4.

[0034] Fig. 7 is a cross-sectional view of the wheel generally taken along lines 7-7 of Fig. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0035] Referring now to the drawings, there is illustrated in Figs. 1 through 7 a vehicle wheel, indicated generally at 10. The wheel 10 generally incudes an inner wheel disc, indicated generally at 12, and an annular outer rim 14. Although the invention is illustrated and described in conjunction with the particular vehicle wheel construction disclosed herein, it will be appreciated that the invention can be used in conjunction with other types of vehicle wheel constructions.

[0036] In a preferred embodiment (and as illustrated herein), the wheel disc 12 and the outer rim 14 are unitarily or monolithically produced or formed, such as for example, as a single casting. After production of the casting, portions of the casting can be machined or otherwise worked to form the wheel 10. Alternatively, the wheel disc 12 and outer rim 14 may be produced separately, such as separate castings and/or non-castings, and then joined together by any suitable means, to produce a "fabricated" vehicle wheel 10. In this fabricated example, the wheel disc 12 is preferably produced as a single casting.

[0037] The wheel 10 can be produced or cast from any suitable material. For example, the wheel 10 may be an all-cast wheel design formed from aluminum or alloys thereof. Aluminum is advantageous in that it is relatively inexpensive, lightweight, easily machinable, and can provide sufficient rigidity. Other suitable materials in which the wheel 10 can be made of include magnesium, titanium or alloys thereof, steel, carbon fiber and/or composite materials. [0038] The combination of the wheel disc 12 and the outer rim 14 defines a wheel axis X for the wheel 10. The outer rim 14 can have any suitable annular shape for receiving and supporting a tire (not shown). In one embodiment, the outer rim 14 is machined after the wheel 10 is cast to provide a continuous annular shape relative to the wheel axis X for accommodating the tire. It should be appreciated that the outer rim 14 can have any desired diameter and/or shape. In a preferred embodiment, the outer rim 14 has an outer diameter within the range of about 381 millimeters to about 610 millimeters.

[0039] As best shown in Fig. 7, the outer rim 14 includes a front facing circumferential edge 15, and a rear facing circumferential edge 16. The outer rim 14 includes a chamfered or sloped sidewall 18 extending inwardly from the front facing circumferential edge 15. The sidewall 18 may have any desired shape. For example, the sidewall 18 may have a frustoconical shape, multiple sloped sides, or have a curved profile, such as shown in Fig. 7. The outer rim 14 further includes a generally tubular or cylindrical central wall 19. It is noted that the central wall 19 need not be perfectly tubular or cylindrical but may include curvatures or bends therein. The sidewall 18 provides for attachment or connection locations of the wheel disc 12 to the outer rim 14. As stated above, the wheel 10 may be formed in a single casting or formation such that the attachment or connection locations between the wheel disc 12 and the outer rim 14 are integrally formed together in the forming process.

[0040] The wheel disc 12 is generally comprised of a central hub, indicated generally at 20, and a plurality of spokes 22 extending radially outwardly from the hub 20. As will be discussed in detail below, the hub 20 includes an outboard perimeter wall, indicated generally at 24, surrounding the hub 20. The perimeter wall 24 provides rigidity for the wheel disc 12 as well as providing for anchoring points or connection points for the radially outwardly extending spokes 22. The perimeter wall 24 generally works as a bridge between the spokes 22. As stated previously, it is preferred that the wheel disc 12 is a single cast component such that the hub 20 and the spokes 22 are all formed together as a single cast. The hub 20 is generally defined as the central portion of the wheel disc 12 from which the spokes 22 extend.

[0041] In the illustrated embodiment, the hub 20 has a front face 26 (or front surface), as seen in Figs. 1, 4, 6 and 7, and a rear face 28 (or rear surface), as seen in Figs. 2, 5, and 6 and 7. The front face 26 is located on the outboard side of the wheel 10 when mounted on a vehicle. The rear face 28 is located on the inboard side of the wheel 10 when mounted on a vehicle. The hub 20 functions as a wheel mounting portion or center mounting portion of the wheel 10 for connecting with an axle (not shown) via a plurality of lug bolts (not shown) and lug nuts (not shown). In a preferred embodiment, the front face 26 of the hub 20 is generally planar and is perpendicular to the wheel axis X, as best shown in Fig. 7. Similarly, in a preferred embodiment, the rear face 28 of the hub 20 is generally planar and is perpendicular to the wheel axis X. The front and rear faces 26 and 28 of the hub 20 may have any suitable shape. AS best shown in Fig. 7, the front and rear faces 26 and 28 define a thickness Hi of the hub 20 therebetween. The thickness Hi of the hub 20 can be any suitable thickness providing appropriate rigidity for the wheel disc 12. In a preferred embodiment, the thickness Hi is within a range of about 10 millimeters to about 30 millimeters. In a more preferred embodiment, the thickness Hi is within a range of about 15 millimeters to about 25 millimeters.

[0042] The hub 20 includes a centrally located pilot aperture or hub hole 30.

The hub hole 30 extends along the wheel axis X. The hub hole 30 may accommodate a portion of the axle and/or receive a protective/decorative cap (not shown). A plurality of lug bolt receiving holes 32 are formed in the hub 20 and are circumferentially spaced around the hub hole 30 and the wheel axis X. In the illustrated embodiment, the hub 20 includes five lug bolt receiving holes 32. The lug bolt receiving holes 32 may be provided in the hub 20 in alignment with a respective one of each of the spokes 22, or positioned between adjacent spokes 22, as shown in the illustrated embodiment. Alternatively, the number and/or location of the lug bolt receiving holes 32 may be other than illustrated if so desired. The lug bolt receiving holes 32 receive the lug bolts (not shown) for securing the vehicle wheel 10 with lug nuts (not shown) on the axle of an associated vehicle.

[0043] The details of the lug bolt receiving holes 32 will now be discussed. As best shown in Figs. 6 and 7, the lug bolt receiving holes 32 define a large diameter bore 33 formed in the front face 26 of the hub 20, and a smaller diameter bore 34 formed in the rear face 28 of the hub 20. Generally, the smaller diameter bores 34 are sized to receive threaded lug bolt shafts (not shown) while the larger diameter bores 33 are sized to receive lug nuts (not shown) and to accommodate a wrench or other tool for fastening the lug nuts to the lug bolts. The bores 33 and 34 define a circular ledge 37 therebetween.

The ledge 37 provides for a contact and mounting surface upon which a lug nut (not shown) is tightened on a corresponding lug bolt to clamp or mount the wheel 10 to the axle. The ledge 37 may be a planar surface perpendicular to the wheel axis X, or may be chamfered or formed as a curved surface to accommodate the contacting or mating portion of the lug nut. Alternatively, the lug bolt receiving holes 32 may be formed as a single hole or bore such that the lug nut will simply contact and engage with the front face 26 of the hub 20 when the wheel 10 is mounted. In the illustrated embodiment shown in Fig. 7, the large diameter bore 33 has a diameter Bi, and the smaller diameter bore 34 has a diameter B2. Although the lug bolt receiving holes 32 may be formed to any size, in a preferred embodiment the diameter B 1 of the large diameter bore 33 is within the range of about 10 millimeters to about 30 millimeters, and diameter B2 of the smaller diameter bore 34 is within the range of about 15 millimeters to about 25 millimeters.

[0044] As best shown in Figs. 2, 5, 6 and 7, the rear face 28 of the hub 20 may include a plurality of optional hub pockets 40 formed therein. The formation of the hub pockets 40 helps to reduce the thickness of the hub 20, thereby reducing the overall mass of the wheel disc 12. The hub pockets 40 are interspaced with the lug bolt receiving holes 32. The hub pockets 40 are also provided at locations generally adjacent to connecting portions of the spokes 22 such that the mass of the hub 20 may be reduced at this region while features of the connecting portions of the spokes 22 provide rigidity at this location. As illustrated, there are five of the hub pockets 40. Alternatively, the wheel disc 12 may have fewer or greater than five of the hub pockets 40. As non-limiting examples, the hub pockets 40 may not be between every pair of the lug bolt receiving holes 32 or more than one hub pocket 40 may be between a pair of the lug bolt receiving holes 32.

[0045] As shown in Fig. 7, the hub pockets 40 each preferably have a depth H2 which is less than the thickness Hi of the hub 20. Thus, the hub pockets 40 preferably do not extend all the way through the hub 20 from the rear face 28 to the front face 26. In other words, in a preferred embodiment, the hub pockets 40 are not through holes formed in the hub 20. Each of the hub pockets 40 defines a radially extending bottom surface 42. In a preferred embodiment, the depth H2 of the hub pockets 40 may range from about 0 millimeters to about 25 millimeters. In a more preferred embodiment, the depth H2 of the hub pockets 40 may range from about 5 millimeters to about 15 millimeters. Of course, it should be appreciated that each of the hub pockets 40 may have the same hub pocket depth H2 or, alternatively, one or more of the hub pockets 40 may have a different hub pocket depth. Alternatively, the hub pockets 40 may be omitted from the wheel disc 12.

[0046] The hub pockets 40 can have any suitable shape. In a preferred embodiment, the hub pockets 40 are formed so as to remove a maximum of material or mass from the hub 20 while maintaining rigidity for the hub 20. Thus, as shown in Fig. 2, a radial outer wall 44 has a length Li which is larger in length compared to length L2 of a radial inner wall 46. The hub pockets 40 may have side walls 48 that are curved to accommodate the curvature of the lug bolt receiving holes 32 formed in opposite front face 26 of the hub 20. This shape of the hub pocket 40 helps in maximizing the absence of material within the hub 20 while maintaining rigidity for the hub 20. The hub pockets 40 have have a radial length L3. In a preferred embodiment, the length Li of the outer wall 44 may range from about 20 millimeters to about 70 millimeters. In a more preferred embodiment, the length Li of the outer wall 44 may range from about 40 millimeters to about 50 millimeters. Consequently, in a preferred embodiment, the length L2 of the inner wall 46 may range from about 15 millimeters to about 45 millimeters. In a more preferred embodiment, the length L2 of the inner wall 46 may range from about 28 millimeters to about 38 millimeters. In a preferred embodiment, the radial length L3 of the hub pocket 40 may range from about 20 millimeters to about 70 millimeters. In a more preferred embodiment, the length L3 of the hub pocket 40 may range from about 40 millimeters to about 50 millimeters. [0047] The hub 20 further defines an outer edge 50 generally surrounding the perimeter of the hub 20. As will be described below, the outer edge 50 of the hub 20 blends in with proximal ends of the spokes 22 at their connecting points with the hub 20. The hub 20 further includes a perimeter wall, indicated generally at 60. The perimeter wall 60 generally extends axially outwardly from the outboard or front face 26 at the outer edge 50. In a preferred embodiment, the perimeter wall 60 loops about the outer edge 50 and has a generally constant height Pi (see Fig. 7) extending from the front face 26. In a preferred embodiment, the height Pi of the perimeter wall 60 may range from about 25 millimeters to about 55 millimeters. In a more preferred embodiment, the height Pi of the perimeter wall 60 may range from about 35 millimeters to about 45 millimeters.

[0048] In a preferred embodiment, the perimeter wall 60 forms a continuous and constant loop that extends from the outer edge 50 without having breaks formed therein. Of course, the perimeter wall 60 could be configured as a non- continuous loop if so desired. The perimeter wall 60 may have any suitable shape. For example, the perimeter wall 60 could have a circular shape, or a non-circular shape, as illustrated. In a preferred embodiment, the perimeter wall 60 defines a plurality of sides or side walls 62. Each of the side walls 62 are connected together at corners 64. In the illustrated embodiment, there are five side walls 62 and five corresponding corners 64, thereby forming a general pentagonal shape at the outboard side of the hub 20, as best shown in Figs. 1 and 4. As will be discussed below, the spokes 22 generally extend from the corners 64 of the perimeter wall 60. The side walls 62 can have any suitable shape. For example, the side walls 62 may be formed generally straight or linear. In the illustrated embodiment, the side walls 62 are curved having a general curvilinear shape. The side walls 62 have a concave shape such that a central portion 66 of the side walls 62 are closer to the wheel axis X than the corners 64. Of course, the side walls 62 could be configured having a convex shape such that the central portion 66 of each of the side walls 62 are further from the wheel axis X than the corners 64.

[0049] The hub 20 and corresponding perimeter wall 60 may be formed having any suitable dimension which provides rigidity for the wheel disc 12 while preferably minimizing the overall mass of the hub 20. As shown in Fig. 1, the perimeter wall 60 may be formed such that the central portion 66 of the side walls 62 extend radially outward by a distance P2 from the wheel axis. In a preferred embodiment, the distance P2 may range from about 50 millimeters to about 140 millimeters. In a more preferred embodiment, the distance P2 may range from about 85 millimeters to about 105 millimeters.

[0050] The perimeter wall 60 may also have any suitable thickness sufficient to provide rigidity while preferably minimizing the overall mass of the wheel disc 12. In the illustrated embodiment, the side walls 62 have a generally constant radial thickness P3 (with the exception of grooves 70 explained in detail below). In a preferred embodiment, the thickness P3 may range from about 6 millimeters to about 30 millimeters. In a more preferred embodiment, the thickness P3 may range from about 12 millimeters to about 24 millimeters. Of course, the side walls 62 need not have a constant thickness and may be formed with a non-continuous or varying thickness along the length of the side walls 62 between respective corners 64. In a preferred embodiment, the side walls 62 are formed having a generally constant rectangular cross-sectional shape, as is best shown in Figs. 6 and 7. It is noted that in the illustrated embodiment that the height Pi of the perimeter wall 60 is greater than the thickness P3 of the perimeter wall 60. Of course, the perimeter wall 60 could be configured oppositely such that the perimeter wall 60 has a greater thickness P3 than the height Pi.

[0051] The hub 20 may be configured with an outer circular chamfer 68 formed in rear face 28 of the hub 20, as best shown in Figs. 2, 6 and 7. The chamfer 68 has a generally frustoconical shape and helps to reduce the overall mass of the hub 20. It is noted that the presence of the chamfer 68 provides for a generally circular shaped rear face 28 (see Figs. 2 and 5), while the five-sided perimeter wall 60 generally provides for a pentagonal shape for the front face 26 of the hub 20. Of course, the hub 20 need not have the chamfer 68 formed therein if so desired.

[0052] As best shown in Figs. 1, 4, 6, and 7, grooves 70 may be formed in the perimeter wall 60 corresponding to the large diameter bores 33 of the lug bolt receiving holes 32. The grooves 70 are formed with the same diameter Bi as the large diameter bores 33. Although the hub 20 could have been formed such that perimeter wall 60 has a wider width (increasing the distance P2) such that the grooves 70 are not necessary, the illustrated embodiment accommodates the large diameter bores 33 while reducing the size of the perimeter wall. This configuration reduces the mass of the perimeter wall 60.

[0053] In the illustrated embodiment, the wheel disc 12 includes five spokes 22 which are shown as being formed integral with the hub 20 and extending radially outwardly from the corners 64 of the perimeter wall 60. Alternatively, the number of the spokes 22 may be other than illustrated if so desired. For example, the vehicle wheel 10 may include less than five spokes 22 or more than five spokes 22. Alternatively, the spokes 22 may be individually formed and secured to the outer rim 14 and the hub 20 by any suitable means and the outer rim 14 may be formed integral but separate from the hub 20 and joined thereto by any suitable method.

[0054] The spokes 22 are preferably essentially identical in structure with one another. Alternatively, one or more the spokes 22 may have differing shapes dependent of the placement about the hub 20. Each of the spokes 22 includes a distal end, indicated generally at 80, connecting to the outer rim 14. Each of the spokes 22 also includes a proximal end, indicated generally at 82 which connect, secure, or otherwise join the spokes 22 to the corners 64 of the perimeter wall 60 of the hub 20. The spokes 22 can have any suitable shape radially extending from the hub 20 to the outer rim 14. Although the spokes 22 may be formed with a constant width and depth as extending along the radial direction, it is noted that in the illustrated embodiment the spokes 22 have a tapered or gradual reduced thickness Si from the proximal ends 82 to the distal ends 80. As shown in Fig. 7, the spokes 22 have a generally constant height S2. In a preferred embodiment, the thickness Si is within a range of about 6 millimeters to about 30 millimeters. In a more preferred embodiment, the thickness Si is within a range of about 10 millimeters to about 18 millimeters. In a preferred embodiment, the height S2 is within a range of about 6 millimeters to about 50 millimeters. In a more preferred embodiment, the height S2 is within a range of about 30 millimeters to about 45 millimeters.

[0055] The spokes 22 can have any suitable shape and need not have a constant cross-sectional shape. The distal ends 80 of the spokes 22 can be connected to the outer rim 14 by any suitable means and by any suitably shaped distal end 80 of the spoke 22. In the illustrated embodiment, the distal ends of the spokes 22 each include relatively small first and second wing portions 86 and 88 extending laterally from the distal ends 80. The formation of the wing portions 86 and 88 provide for a more robust connection point to the sloped sidewall 18 of the outer rim 14. As stated above, the wheel disc 12 and the outer rim 14 are preferably unitarily or monolithically produced or formed, such as for example, as a single casting. The wing portions 86 and 88 may have any suitable shape to accommodate connecting the distal ends 80 of the spokes 22 with the outer rim 14.

[0056] As stated above, the perimeter wall 60 preferably has a general constant height Pi extending from the front face 26 of the hub 20. This provides for a generally planar front surface 90 formed on all of the five side walls 62 and five corners 64. In the illustrated embodiment, the front surface 90 of the perimeter wall 60 has a generally pentagonal looped shape. In a preferred embodiment, each of the spokes 22 defines an outer front surface 92 that are co-planar with one another. Additionally, the front surfaces 92 of the spokes 22 are preferably co-planar with the front surfaces 90 of the perimeter wall 60 providing a combined flush planar surface as best shown in Fig. 7.

[0057] The embodiments of the various wheels and wheel discs described herein offer several advantages over conventionally known wheels. The embodiments of the wheel discs described herein were designed by a topology optimization methodology to obtain such advantages. For example, it is conventionally known that to increase the stiffness of the wheel, the mass of the wheel is generally increased. However, the wheel embodiments described herein have obtained an increase in stiffness while reducing the mass or weight of the wheel. It has been found that an increase in stiffness of about 38% can be obtained while reducing the weight by about 19% compared to conventionally known similar sized and similar material wheels. These advantages can be obtained by utilizing the bridge as the border of the hub/spoke junction to provide stiffness and rigidity, and/or providing a variational spoke cross section such that structural mass is allocated wherever necessary. These advantages are particular useful for wheels specifically designed for electric vehicles. Wheels for electric vehicles generally demand a relatively low weight or mass so that longer battery range distance can be obtained in such vehicles. Additionally, high stiffness of the wheels is preferred to help reduce NVH (Noise vibration and Harshness) created by the tire/wheel interaction. Since electrical vehicles are often less noisy compared to combustion engine vehicles, the perception of noise generated by the wheels can be more readily heard by the vehicle occupants and thus a reduction in wheel noise is greatly beneficial. The embodiments of the wheels described herein can be utilized for all types of wheel designs such as wheels and/or wheel discs manufactured in alloys such as magnesium, aluminum, steel, and/or a composite. Additionally, the embodiments of the wheels described herein are applicable to vehicle wheels having various dimensions such as wheels having diameters from about 381 millimeters (15 inches) to about 610 millimeters (24 inches), and having widths from about 88.9 millimeters (3.5 inches) to about 300 millimeters (11.8 inches).

[0058] The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.