This invention relates generally to a vehicular hub cap, and more particularly to attachment features formed in a hub cap to enhance attachment integrity under harsh environmental conditions.
Decorative wheel covers form an important part of a vehicle's appeal, and can be used to cover portions or all of an outward-facing surface of a vehicular wheel. Such covers allow conventional fabricated steel wheels to emulate the aesthetically-pleasing attributes of polished, chrome-plated or cast aluminum wheels at a small fraction of the cost. Most wheels for such applications include a rim section, a spoke (or web) section and a central hub section, the latter of which allows for connection between the wheel and an axle. The hub section is one area of the wheel's outward-facing surface that can especially benefit from decorative covers, as otherwise unsightly lugs, lug nuts and axle spindles are left exposed. Wheel covers that overlie the hub section are often referred to as hub caps.
Increasingly, hub caps are made from inexpensive, lightweight, non-metallic materials (for example, plastic) that are easily formable, impact-resistant, and (with the placement of an appropriate metallized coating on a surface thereof) capable of providing a desirable level of metallic finish and luster. In another form, hub caps could have the color molded-in, or coated with a secondary finish, such as paint or the aforementioned metallized finish. While the use of highly decorative hub caps is in its ascendancy, difficulties in reliably and inexpensively securing these hub caps to the underlying wheel or lug nuts used to secure the wheel to an axle jeopardize their long-term viability. Fasteners, such as resilient snap-fit extensions on the back (inward-facing) surface of the cover, can be employed to keep the cover affixed to the wheel to withstand the sort of rotational and vibration loading typically encountered in a vehicular environment. Often, these snap-fit fasteners are integrally formed (i.e., unitary, or one-piece) with the wheel cover. Other resilient fasteners, forming a friction-fit rather than a snap-fit, have also been used. In an alternative to snap-fit and friction-fit fasteners, high-strength adhesives have also been used. The use of such adhesives, while potentially beneficial for thermal protection of, and acoustic enhancement to, wheel covers, necessitates relatively detailed placement and assembly procedures to ensure weight minimization, adequate affixation and dynamic balancing, with concomitant increases in manufacturing costs. As such, the use of the aforementioned resiliently-biased snap-fit and friction-fit fasteners has enjoyed a prominent place in the wheel cover market.
Nevertheless, the fasteners, which are typically in the form of cantilevered, tubular cups with segmented, finger-like extensions formed on the inner surface of the hub cap can soften, creep or otherwise suffer reduced grip on the lug nuts as a result of high temperature and rotational loads. These conditions result from wheel rotation and braking. For example, braking in loaded trucks can produce temperatures in the lugs and lug nuts of up to 400 degrees Fahrenheit, a temperature that would soften (if not outright destroy) many conventional plastic materials. Furthermore, differences in the rate of thermal expansion of the metallic wheel and the plastic hub cap can exacerbate an already loose or weakened fastener connection. In addition, individual fingers within the fasteners may be susceptible to breakage due to improper alignment, mounting and handling. Other approaches may employ multi-piece construction with metallic fasteners. While such a construction may have the advantage of better resistance to the buildup of heat, it does so with increases in weight and cost through the use of stamped metal parts that may require coating or related environmental protection to avoid the effects of rust or related corrosion. Moreover, schemes to attach the fasteners to the hub cap may be susceptible to heat or vibration-induced wear and subsequent separation, as friction-fit connections can work their way loose over extended periods of operation.
What is needed is a way to secure a hub cap to a wheel inexpensively and reliably under all of the conditions normally encountered in a vehicular environment. Also desired is a hub cap that can satisfy the above needs without using metal-based structural components.
These needs are met by the present invention, where a hub cap can be affixed to a wheel to ensure a durable, robust connection between the two. In a first aspect of the invention, the hub cap includes a non-metallic body portion defining an inner (inward-facing) surface and an outer (viewable) surface, and a non-metallic wheel coupling portion extending from the inner surface of the body portion. In the present context, the term “non-metallic” and its variants is used to define the material makeup of the main structural attributes of the body portion and the wheel coupling portion. The incidental use of metal for chiefly aesthetic reasons, such as the placement of a metallized coating to give a chrome or related glossy finish on the surface of the body portion, is not inconsistent with such coated portion being construed as non-metallic. The wheel coupling portion comprises a plurality of resiliently biased, lug nut engaging members disposed about the periphery of the body portion and axially alignable with lug nuts disposed on a wheel.
The resiliently biased configuration of the lug nut engaging members may be due to, for example, a cantilevered construction of the members relative to the body. By engaging the lug nut, the lug nut engaging members radially deflect to an extent necessary to cooperate with one another to keep the hub cap attached to the wheel. Each of the lug nut engaging members includes a substantially arcuate base configured to engage axially at least one surface of the lug nut, and a substantially arcuate crown axially aligned with and disposed axially inward relative to the substantially arcuate horizontal base. Inherent in an arcuate structure is the partial, bow-like contact area with the device it surrounds. By having only a portion of the circumference of a lug nut engaged rather than substantially full circular contact area, the present lug nut engaging members provide more assembly tolerance, as well as reduced susceptibility to member breakage. In the present context, the term “substantially” is utilized to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. As such, it refers to an arrangement of elements or features that, while in theory would be expected to exhibit exact correspondence or behavior, may in practice embody something slightly less than exact. The term also represents the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.
Optionally, the lug nut engaging members include numerous anti-rotation standoffs disposed about the base. These standoffs may, for example, include generally planar surfaces that can be placed against the faceted outward surfaces of a standard hexagonal-shaped lug nut to inhibit nut rotation. The lug nut engaging members may include an axial stiffening rib to enhance flexural resistance. Such flexure (i.e., radial deflection) of the members may be caused by, among other things, contact with the lug nuts, high rotational (centrifugal) loading or the like. The crown may define a castellated structure, which may include beveling to promote ease of insertion with a corresponding lug nut. In a particular form, the base and crown define a radially outward portion of each of the lug nut engaging members. A retaining wire may be disposed on this radially outward-facing surface of the lug nut engaging members. This wire can be made from a variety of structural, relatively temperature-resistant materials, including ceramics (including fiber-reinforced ceramic composites), high temperature plastics or metal. Furthermore, a series of brackets may be formed in the inner surface of the hub cap body portion to allow a secure fit of the wire.
In one variant of the hub cap design, the lug nut engaging members can be integrally formed with the body portion to define a one-piece hub cap design. In another variant, the lug nut engaging members are integrally formed with one another on a common ring, which in turn can be removably attachable to the body portion, thereby resulting in a two-piece hub cap design. In this latter configuration, a boss can be formed on the inner surface of the hub cap body portion. The boss can define an aperture therein to allow passage of projecting connectors (also referred to as projections) situated on the ring. In one form, the projections are resiliently-biased snap-fit detents that are integrally formed in the ring. At least one of the ring and the hub cap can be made from a plastic, ceramic or continuous or discontinuous reinforced composite based on plastic or ceramic. In situations where excessive heat soaking may be experienced, the ring can be molded from a separate, higher-temperature plastic, ceramic or composite material, such as a glass-reinforced nylon. To enhance the outward appearance of the hub cap, a metallic (for example, chrome or chrome-like) coating may be used in the body portion. In another form, colors may be painted onto or molded in the body portion to enhance its appearance.
In the one-piece variant of the hub cap, the lug nut engaging members form a substantially cantilevered attachment to the body portion. In this way, the base forms a proximal end (i.e., closest to the point of connection between the body portion and the lug nut engaging members), while the crown defines a distal end. The inherent flexibility in a cantilever structure allows the distal portion adjacent the crown to move radially relative to the proximal end and the body portion. As with the two-piece variant discussed above, plastic, ceramic or composite materials may be used. Also as with the two-piece variant discussed above, the outward appearance of the hub cap can be augmented by the addition of a metallic coating, painted-on coating or through molded-in color.
According to another aspect of the invention, a hub cap, comprising a body portion and a wheel coupling portion, is disclosed. The body portion defines an inner surface and an outer surface. The inner surface comprises a boss with an aperture that allows the wheel coupling portion to be removably attachable. The wheel coupling portion includes a ring, numerous circumferentially spaced and resiliently biased lug nut engaging members disposed on the ring, and a plurality of projections disposed on the ring. The projections are oriented to engage the boss aperture to facilitate connection between the wheel coupling portion and the body portion. The lug nut engaging members extend axially inward and are alignable with corresponding lug nuts disposed on a wheel. Each of these members includes a proximal end, defining a base configured to engage axially a corresponding one of the lug nuts, and a distal end, defining a substantially arcuate crown axially aligned with, and disposed axially inward relative to, the base. In this way, radial deflections imparted to each of the crowns by the lug nuts promote a secure connection between the hub cap and the wheel.
Optionally, the projections comprise snap-fit detents. The snap-fit detents preferably define an angled distal portion. Likewise, the boss aperture defines a beveled surface to facilitate the insertion of the angled distal portion of snap-fit detents. As stated in conjunction with an earlier aspect, the lug nut engaging members and the projections can be integrally formed with the ring, where the ring, lug nut engaging members and projections can be made from a temperature-resistant, non-metallic material.
According to another aspect of the invention, a wheel assembly includes a wheel and a hub cap configured to cover at least a portion of the wheel. The hub cap includes a body portion defining an inner surface and an outer surface, and a wheel coupling portion extending from the inner surface of the body portion. The wheel coupling portion comprises a plurality of circumferentially spaced and resiliently biased lug nut engaging members that are axially alignable with corresponding lug nuts. The lug nut engaging members are configured to secure the wheel to a vehicle. Each of the lug nut engaging members includes a substantially arcuate base configured to engage axially a corresponding one of the lug nuts, and a substantially arcuate crown, axially aligned with and disposed axially inward relative to the base. As before, radial deflections imparted to each of the lug nut engaging members cause them to cooperate with the lug nuts, thereby keeping the hub cap attached to the wheel.
Optionally, the lug nut engaging members can be either integrally formed with the body portion to define a one-piece structure, or can be integrally formed with one another on a common ring. In this latter (two-piece) configuration, the ring includes numerous snap-fit detents that make the ring removably attachable to the body portion by engaging the snap-fit detents through an aperture defined in a boss formed on the inner surface.
According to still another aspect of the invention, a method of covering a vehicular wheel is disclosed, where the wheel includes an inner surface, an outer surface and a plurality of lug nuts protruding substantially outward from the outer surface. It will be appreciated that the wheel outer surface is that which is viewable by an observer standing away from the vehicle when the wheel is mounted onto the vehicle. The method includes providing a wheel and a hub cap and securing the hub cap to the wheel such that lug nuts used to secure the wheel to an axle or other part of a vehicle impart a radial deflection to corresponding lug nut engaging members, thereby causing them to keep the hub cap attached to the wheel. As before, the hub cap includes a body portion and a wheel coupling portion extending from an inner surface of the body portion. The wheel coupling portion includes numerous circumferentially spaced and resiliently biased lug nut engaging members. Each of the lug nut engaging members includes a base to engage axially one of the lug nuts, and a substantially arcuate crown axially aligned with and disposed axially inward relative to the base.
Optionally, the method includes configuring the wheel coupling portion as a ring with extending lug nut engaging members, and creating a snap-fit connection between the ring and the body portion to facilitate removable attachment between the ring and body portion. At least one of the body portion and the ring may be made from the aforementioned ceramic, plastic or composite based on either or both. As previously discussed, the method may include reinforcing the lug nut engaging members with a retaining wire.
In a preferred (although not necessary) embodiment, the hub cap 300 is made from a non-metallic material, such as plastic or related resin, examples of which may include acrylonitrile-butadiene-styrene (ABS), polycarbonate or a combination thereof. The material may further include continuous or discontinuous fiber reinforcements, such as glass, polymers, ceramics or the like. The hub cap 300 includes an outer surface 310 and inner surface 320. A body portion of hub cap 300 defines the general external configuration, while a wheel coupling portion, which cooperates with inner surface 320 and is discussed in more detail below, promotes secure connection between the hub cap 300, and the wheel 200 or the lug nuts 30, or both. In the present context, the outer surface of the hub cap 300 is that which is visible to an observer when the wheel 200 is mounted to an automobile or related vehicle and is covered by the hub cap 300. Accordingly, the outer surface 310 of hub cap 300 is configured to provide an aesthetically-pleasing cover for at least a portion of central hub section 220, and may (among other things) be metallized with an appropriate coating to define a chrome-like or related appearance. The inner surface 320 may or may not include a metallized coating, depending on the need or on the method of manufacture. For example, a metallized coating may or may not be placed on the inner surface 320, depending on whether the hub cap 300 is masked prior to coating deposition. In another variation on aesthetic enhancement, the hub cap may include molded-in coloring or have its outer surface painted.
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Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.