60/046,257, filed on April 12, 1997.

BACKGROUND OF THE INVENTION This invention relates in general to full face two piece wheel assemblies for vehicles, and in particular to a two piece wheel assembly having a full face wheel disc assembled upon and a partial wheel rim by a sliding fit.

Traditionally, vehicle wheels adapted for receiving pneumatic tires have been fabricated from sheet steel. Such wheels usually include a rim formed from a strip of steel which is rolled into a hoop. The ends of the hoop are butt welded together to form an annular preform. The preform is shaped into a wheel rim by conventional rolling processes which roll inboard and outboard tire bead retaining flanges, inboard and outboard tire bead seats and a center deep well into the preform. A circular wheel disc or spider, which is formed by a conventional stamping or pressing process, is welded within the interior of the rim. The wheel disc or spider has a centrally disposed pilot hole and a plurality of mounting holes formed therethrough. Typically, the wheel disc has been located at or near the axial mid-plane of the wheel rim.

With the advent of front wheel drive vehicles, which tend to include not only larger brake assemblies but also steering and drive components adjacent the front wheel hubs? it has become necessary to offset the wheel disc from the axial mid-plane position outwardly toward the outboard tire bead retaining flange.

When the wheel disc is located at the outboard end of the wheel rim, the outboard tire bead retaining flange can be formed integrally thereon. Such a wheel disc is often referred to as a full face wheel disc. A partial wheel rim, which has a

cylindrical outboard end, is attached to the inboard surface of the full face wheel disc. The assembled full face wheel disc and partial wheel rim are typically called a full face wheel. Such full face wheels are the subject of this patent application.

Because the wheel disc has moved outwardly to a more visible position, the wheel disc has an increased significance as a styling element of the vehicle. It has become common to form full face wheel discs by such processes as casting or forging to provide a highly stylized, decorative and distinctive appearance.

Accordingly, significant attention has been paid to not only to the mechanical configuration of such full face wheels but also to the aesthetic design thereof within the last several years.

One type of full face wheel assembly includes a full face cast or forged disc and a rolled partial rim. The rim and disc are welded together to form a full face wheel. For example, a full face wheel assembly of this type is described in U.S.

Patent No. 5,360,261. This structure combines the design freedom afforded by casting the wheel disc face with the higher strength to weight ratio of the rim afforded by metal forming processes.

SUMMARY OF THE INVENTION This invention relates to a full face two piece wheel having a full face wheel disc assembled upon and a partial wheel rim by a sliding fit and a process for fabricating such a wheel.

As described above, one type of full face wheel assembly includes a full face cast or forged disc and a rolled rim which are welded together. In the past, an annular inboard edge of the disc has been radially aligned with an annular outboard edge of the rim. Alternately, a shoulder is formed on the disc as a positive stop for the rim. The disc and rim have been joined by pushing together the edges and applying a weld. In this type of structure, the width or lateral runout of the wheel assembly has been controlled by very accurately machining the joining edges of both the disc and rim. The required machining can be costly and time consuming.

Also, the disc and rim are usually joined with a weld along the entire 360 degree

circumference between the joining edges to assure an air-tight seal between the disc and rim. Such welds require relatively long and costly weld cycle times.

Thus, it would be desirable to provide a full face wheel assembly that reduces the costs of machining and welding.

The present invention contemplates a two piece full face wheel which includes a full face wheel disc having a cylindrical shoulder which extends axially from an inboard surface thereof. A cylindrical outboard end of a partial wheel receives the wheel disc shoulder by a sufficient distance to form a wheel assembly and define a lateral runout for the wheel assembly. A weld formed between the wheel disc shoulder and the outboard rim end secures the wheel disc to the wheel rim.

The wheel disc shoulder can be slidingly received within said outboard wheel rim end or the wheel rim end can be slidingly received by the wheel disc shoulder. Alternately, the wheel disc and wheel rim can be press fit or shrunk fit together. The wheel also can include a resilient material disposed between the wheel disc shoulder and the outboard wheel rim end. The resilient material forms an air-tight seal between the wheel disc and the wheel rim. In the preferred embodiment, the wheel disc shoulder and the wheel rim end co-operate to form a wheel deep well. The weld can include one or more spot welds. Alternately, a circumferential air-tight weld can be formed between the wheel disc and the wheel rim.

The invention also contemplates a process for forming a two piece wheel.

The process includes forming a full face wheel disc which includes a cylindrical shoulder extending axially from an inboard surface thereof. A partial wheel rim which includes an inboard tire bead retaining flange and a cylindrical outboard end is also formed. The wheel disc is assembled onto the outboard rim end and the wheel disc is secured to the wheel end to form a wheel assembly.

In the preferred embodiment, the invention contemplates that the wheel rim end can be slid over the wheel disc shoulder. However, the wheel rim end also can be pressed over or heat shrunk fit onto the wheel disc shoulder. Additionally, in

the preferred embodiment, the wheel disc is welded onto the wheel rim end.

Alternately, the wheel disc shoulder can be slid over the outboard end of the wheel rim.

Various objects and advantages 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 Fig. 1 is a front view of a two piece full face wheel according to the present invention.

Fig. 2 is a sectional view of the wheel illustrated in Fig. 1, taken along the line 2-2.

Fig. 3 is a partial sectional view of an alternate embodiment of the wheel shown in Fig. 2.

Fig. 4 is a partial sectional view of another alternate embodiment of the wheel shown in Fig. 2.

Fig. 5 is a flow chart of a process for fabricating the full face wheel shown in Fig. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to Figs. 1 and 2, a full face wheel assembly according to the present invention is illustrated and generally designated by the reference numeral 10. The full face wheel assembly 10 comprises an axially outboard full face disc 12 attached to an axially inboard partial wheel rim 14. The wheel disc 12 includes a centrally disposed pilot opening 16 formed therethrough. A plurality of wheel lug holes 18, which are uniformly disposed about the pilot hole 16, also are formed through the wheel disc 12. The wheel lug holes 18 receive mounting studs (not shown) which extend from the vehicle wheel hub (not shown). The disc 12 includes a plurality of spokes 20 or other structures which define a plurality of through openings 22. The through openings 22 assist in ventilation ofthe vehicle

disc brake assemblies or other components positioned within the wheel assembly 10.

The disc 12 also includes an outboard tire bead retaining flange 24, an outboard tire bead seat 26 and an outboard safety hump 28. A lightener channel 30 extends continuously around the disc 12 radially inwardly from the bead seat 26 and safety hump 28. The lightener channel 30 provides substantial weight reduction and reduced moment of inertia for the wheel assembly 10. The disc 12 further includes a cylindrical shoulder 32 formed on the inboard side of the disc, and extending axially toward the rim 14. The shoulder 32 forms an outboard portion of a deep well 34. The shoulder 32 includes a radially outer surface 36, a radially inner surface 38 and an inboard edge 40. In the preferred embodiment, the inboard edge 40 is chamfered for a purpose which will be described below; however, the chamfer is optional. The shoulder 32 has an inner diameter 42 and an outer diameter 44.

The wheel disc 12 may be readily cast by a conventional process, such as gravity or low pressure casting, in a mold which is relatively simple compared to the complex mold required to produce a single piece cast wheel. Alternatively, the disc 12 may be forged. In the preferred embodiment, the disc 12 is made of an alloy of aluminum, magnesium, titanium or a similar lightweight, high strength metal.

The partial wheel rim 14 includes an inboard tire bead retaining flange 46, an inboard tire bead seat 48, an inboard safety hump 50 and a leg 52. The rim 14 further includes a cylindrical outboard end 54 which forms an inboard portion of the deep well 34. The outboard end 54 of the wheel rim 14 includes a radially outer surface 56, a radially inner surface 58 and an outboard edge 60. In the preferred embodiment, the outboard edge 60 is chamfered; however, the chamfer is optional. The outboard end 54 has an inner diameter 62 and an outer diameter 64.

The wheel rim 14 may be fabricated by butt welding together the ends of a strip of aluminum formed into a hoop and then forming the hoop by conventional rolling or spinning operations into the shape illustrated in Fig. 2. The rim material

is preferably an alloy of aluminum but may also be an alloy of magnesium, titanium or a similar lightweight, high strength metal. Alternately, the rim 14 can be formed from steel.

The distance between the outboard tire bead retaining flange 24 formed upon the wheel disc 12 and the inboard tire bead retaining flange 46 formed upon the wheel rim 14 defines the width or lateral runout 66 of the wheel assembly 10.

For prior art two piece wheels, the inboard edge 40 of the disc 12 would have been radially aligned with the outboard edge 60 of the rim 14 to form a butt joint (not shown). An air tight circumferential weld would then have been applied about the butt joint to secure the wheel rim to the wheel disc. The lateral runout 66 of such a wheel assembly would have been controlled by very accurately machining both of the edges 40 and 60, which was costly and time consuming. Additionally, any misalignment of the wheel disc and wheel rim could adversely affect the concentricity of outboard and inboard tire bead seats.

In contrast, the present invention contemplates that the wheel assembly 10 includes a sliding fit between the wheel disc 12 and wheel rim 14. Specifically, the wheel disc shoulder 32 has an outside diameter 44 which is slightly less than inside diameter 62 of the outboard wheel rim end 54 so that the shoulder 32 is slidingly received within the rim end 54 when the wheel 10 is assembled. Alternately, the outside diameter 44 of wheel disc shoulder 32 can be selected to provide an interference fit with the wheel rim end 54. As shown in Fig. 2, the disc 12 and rim 14 are pushed together between opposing rings 68, 70 of a suitable fixture. The distance of movement of the rings 68, 70 controls the lateral runout 66 of the wheel assembly 10. The rings 68, 70 push on outer surfaces 72, 74 of the disc 12 and rim 14, respectively. These outer surfaces 72 and 74 have dimensions which can be controlled very well and at low cost. Accordingly, the inboard edge 40 of the disc 12 and the outboard edge 60 of the rim 14 do not have to be accurately machined to control the lateral runout 66. Thus, the cost of machining the wheel assembly 10 is reduced compared to previous wheel assemblies.

In the preferred embodiment, the outboard wheel rim end 54 has an inner diameter 62 which is slightly smaller than the outer diameter 44 of the shoulder 32.

This produces a press fit, as described above, between the wheel rim end 54 and the wheel disc shoulder 32. It is contemplated that the press fit provides an air- tight seal for the rim/tire cavity. The inboard edge 40 of the wheel disc shoulder 32 and the outboard edge 60 of the wheel rim 14 are chamfered to facilitate assembly of the disc and rim in the press fit. If a sliding fit is formed between the wheel disc shoulder 32 and rim end 54, a resilient material (not shown) can be disposed, if needed, between the wheel rim end 54 and the wheel disc shoulder 32 to assure an air-tight seal between the wheel rim 14 and the wheel disc 12.

The wheel rim 14 is secured to the wheel disc 12 by a weld 76 formed between the wheel disc shoulder 32 and the outboard wheel rim end 54. The weld 76 can be an inside diameter weld formed between the inboard edge 40 of the wheel disc 12 and the inner radial surface 58 of the wheel rim 14, as shown in Fig.

2. Alternatively, the weld 76 can be an outside diameter weld (not shown) formed between the outboard edge 60 of the wheel rim 14 and the outer radial surface 36 of the wheel disc 12, or both inside diameter and outside diameter welds (not shown) can be formed. If the wheel disc shoulder 32 and the wheel rim end 54 are assembled in an air-tight press fit, the weld 76 does not have to be applied along the entire 360 degree circumference of the joint between the disc and rim. Instead one or more non-circumferential or spot welds can be used to attach the wheel rim 14 to the wheel disc 12. The use of shorter, non-circumferential, welds or spot welds results in faster weld cycle times.

While the invention has been illustrated in terms of a wheel assembly 10 in which the outboard rim end 54 has a larger diameter than the wheel disc shoulder 32, it will be appreciated that the invention also can be practiced for a wheel assembly 80 in which the wheel disc 12 has a shoulder 81 having a larger diameter than the outboard end 82 of the wheel rim 12, as shown in Fig.3. Components in Fig. 3 which are the same as components shown in Fig. 2 have the same numerical

designators. In Fig. 3, the outboard rim end 82 is slidingly received within an annular cavity defined by the wheel disc shoulder 81.

Both wheel assemblies 10 and 80 shown in Figs. 2 and 3 illustrate the disc shoulder 32 and 81, respectively, co-operating with the rim end 54 and 82, respectively, to form the wheel deep well 34. The specific structures of the wheel assemblies 10 and 80 are intended to facilitate the description of the preferred embodiment of the invention, but other structures are also contemplated for use in the invention. For example another alternate embodiment to the wheel assembly is shown generally at 85 in Fig. 4. As before, components shown in Fig. 4 which are similar to components shown in Figs. 2 and 3 have the same numerical designators.

In Fig. 4, the partial wheel rim 14 includes the wheel deep well 34 and a portion of the outboard tire bead seat 86. The portion 86 of the outboard tire bead seat extends over an annular shoulder 87 which extends axially from the inboard face of the wheel disc 12. A resilient material 88 is disposed between the wheel bead seat portion 86 and the wheel disc 12 to assure an air-tight connection therebetween. A weld 89 secures the wheel rim 14 to the wheel disc 12. Accordingly, it is contemplated that the invention can be practiced for other wheel assembly structures.

While the illustrated embodiment includes a press fit or sliding fit between the wheel disc shoulder 32 and the outboard rim end 54, the shoulder 32 and outboard end 54 can also be assembled with a shrink fit. In the preferred shrink fit embodiment, the rim end 54 is heated to increase the diamete-r thereof. The wheel rim end 54 is then placed over the wheel disc shoulder 32 and allowed to cool. As the wheel rim end 54 cools, the metal contracts onto the wheel disc shoulder 32 to form an air-tight seal. Additionally, an optional layer of a resilient material can be deposited upon the disc shoulder 32 before assembling the wheel to assure an air- tight seal between the wheel disc 12 and the rim end 54. Alternately, the wheel disc shoulder 32 can be heated to increase the diameter thereof. Instead of heating, a wheel component also can be cooled to reduce the diameter thereof to facilitate the assembly of the components.

The invention further contemplates a process for fabricating the wheel assemblies shown in Figs 1 through 4. The process is illustrated by the flow chart shown in Fig. 5. In functional block 95, an outboard full face wheel disc is formed by a conventional method such as casting or forging. The wheel disc includes an outboard tire bead retaining flange, an outboard tire bead seat, an outboard safety hump, and a cylindrical shoulder. A resilient sealing material can be applied to the shoulder in functional block 96 to assure an air-tight seal between the disc and rim; however, this step is optional. Concurrently, in functional block 97, an inboard partial wheel rim is formed by a conventional method such as rolling or spinning.

The rim includes an inboard tire bead retaining flange, an inboard tire bead seat, an inboard safety hump, and a cylindrical outboard end. In functional block 98, the disc and rim are assembled by sliding together the shoulder of the disc and outboard end of the rim so that the wheel disc shoulder is slidingly received within the outboard wheel rim end, as illustrated in Fig. 2, a sufficient distance to provide the desired lateral runout for the wheel assembly. Alternately, the outboard wheel end can be slidingly received within the wheel disc shoulder, as illustrated in Fig.

3. Similarly, a the outboard end of the wheel rim can be pressed into or onto the wheel disc shoulder with an interference fit therebetween. Alternately, the wheel rim end can be or shrink fit onto the shoulder in functional block 98 to assemble the wheel. Then, in functional block 99, a weld is formed between the shoulder of the disc and the outboard end of the rim to secure the disc to the rim. As described above, the weld can be a circumferential air-tight weld or one or more spot welds.

While the preferred embodiment of the invention has been illustrated and described for fabricating wheels having a predetermined lateral runout, it will be appreciated that the invention also can be practiced to manufacture wheels having the same diameter but different lateral runouts. Such wheels could accommodate pneumatic tires having the same diameter, but different widths. Use of the invention would allow use of the same full face wheel discs and partial wheel rims to fabricate a number of different wheels. Accordingly, the inventory of different

wheel components and the number of wheel disc molds required to cast the wheel components could be reduced.

In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. 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.