Abstract:
A decorative cap and fastener for fastening a wheel to a hub of a vehicle are provided. The fastener includes a fastener head including an outer surface and an internal surface defining a cavity. The cap includes an end wall having an external surface and an internal surface. The cap further includes a side wall extending from an outer periphery of the end wall. The cap also includes a central member extending longitudinally from the internal surface of the end wall within the side wall.

Description:
BACKGROUND 
     The wheel of a passenger vehicle is typically mounted to a hub bearing assembly using either a stud and nut configuration or a wheel bolt configuration. A wheel stud is generally press fit from an internal side of the hub and extends outwardly through the rotor. The wheel is mounted onto a plurality of such wheel studs and wheel nuts are used to hold the wheel onto the stud. 
     Wheel bolts are generally inserted from the outside through the wheel and into a threaded hole in the hub. Various wheel bolts are known having different features for driving the wheel bolt. For example, some wheel bolts have a hexagonal head that fits a typical wrench or socket. Other wheel bolts have a security design requiring a special adaptor to engage the wheel bolt. The security design helps prevent a thief from being able to easily remove the wheel. Wheel bolts may generally be designed for load bearing rather than ornamental design. Further, wheel bolts may be exposed to weather and road grime, which may cause corrosion. Wheel bolt caps are used to cover the wheel bolt cap for ornamental and protective purposes. Wheel bolt caps, however, may fall off of the wheel bolts. 
     In view of the foregoing, there is a need for improvements to wheel bolt caps. Further advantages will become apparent from the disclosure provided below. 
     SUMMARY 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the DETAILED DESCRIPTION. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     According to one aspect of the present disclosure, a decorative cap and fastener for fastening a wheel to a hub of a vehicle are provided. The fastener includes a fastener head including an outer surface and an internal surface defining a cavity. The cap includes an end wall having an external surface and an internal surface. The cap further includes a side wall extending from an outer periphery of the end wall. The cap also includes a central member extending longitudinally from the internal surface of the end wall within the side wall. 
     In another aspect of the present disclosure, a cap for covering a fastener, includes an end wall having an external surface and an internal surface. The cap also includes a side wall extending from an outer periphery of the end wall. The cap also includes a central member extending longitudinally from the internal surface of the end wall within the side wall. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features believed to be characteristic of the disclosure are set forth in the appended claims. In the descriptions that follow, like parts are marked throughout the specification and drawings with the same numerals, respectively. The drawing figures are not necessarily drawn to scale and certain figures may be shown in exaggerated or generalized form in the interest of clarity and conciseness. The disclosure itself, however, as well as a preferred mode of use, further objects and advances thereof, will be best understood by reference to the following detailed description of illustrative aspects of the disclosure when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  illustrates a longitudinal cross-section of an example wheel bolt and wheel bolt cap in accordance with aspects of the present disclosure; 
         FIG. 2  illustrates a longitudinal cross-section of another example wheel bolt and wheel bolt cap in accordance with aspects of the present disclosure; 
         FIG. 3  illustrates an example tool for removing a wheel bolt cap in accordance with aspects of the present disclosure; 
         FIG. 4  illustrates an example tool for removing a wheel bolt cap in accordance with aspects of the present disclosure; 
         FIG. 5  illustrates an example tool for removing a wheel bolt cap in accordance with aspects of the present disclosure; 
         FIG. 6  illustrates a bottom perspective view of an example wheel bolt cap in accordance with aspects of the present disclosure; 
         FIG. 7  illustrates a transverse cross-section of an example wheel bolt cap in accordance with aspects of the present disclosure; 
         FIG. 8  illustrates an top plan view of an example wheel bolt cap in accordance with aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following includes definitions of selected terms employed herein. The definitions include various examples and/or forms of components that fall within the scope of a term and that may be used for implementation. The examples are not intended to be limiting. 
     A “vehicle,” as used herein, refers to any moving vehicle that may be capable of carrying one or more human occupants and is powered by any form of energy. The term “vehicle” includes, but is not limited to: cars, trucks, vans, minivans, SUVs, motorcycles, scooters, boats, personal watercraft, and aircraft. In some cases, a motor vehicle includes one or more engines. 
     Generally described, the present disclosure provides for a wheel bolt cap with a firm interference fit to the head of a wheel bolt for a vehicle. The wheel bolt cap may include a central interior protrusion that interferes with an internal surface of the wheel bolt cap. The wheel bolt cap may be made from a different material than the wheel bolt and may have a greater coefficient of thermal expansion. When the temperature decreases, the wheel bolt cap may shrink more than the wheel bolt head. Accordingly, the side walls of the wheel bolt cap may squeeze the external surface of the wheel bolt head. When the temperature increases, the wheel bolt cap may expand more than the head of the wheel bolt. Although the interference between the side walls of the wheel bolt and the external surface of the wheel bolt head may decrease, the interference between the central interior protrusion and the internal surface of the wheel bolt head may increase. Accordingly, the wheel bolt cap may maintain a desired interference fit with the wheel bolt head regardless of the temperature. 
     Turning to  FIG. 1 , a diagram  100  of a longitudinal cross-sectional view of an example wheel bolt  110  and wheel bolt cap  120  is illustrated. The wheel bolt cap  120  is shown in attached to the wheel bolt  110 . As will be described in further detail below, the wheel bolt cap  120  may be press fit onto the wheel bolt  110 . For example, the wheel bolt cap  120  may be attached to the wheel bolt  110  after the wheel bolt has been screwed into the vehicle hub to retain the wheel. 
     The wheel bolt  110  may include a bolt head  112 , a flange  114 , a washer  116 , and a threaded shaft  118 . The bolt head  112  may have a hexagonal outer surface matching a standard socket size, for example, 17 mm, 19 mm, 21 mm, 22 mm, ¼ inch, 13/16 inch, or ⅞ inch. The bolt head  112  may include a center cavity  113  defined by an inner surface of the bolt head  112 . The center cavity  113  may reduce the total weight of the wheel bolt  110  compared to a wheel bolt having a solid bolt head. The center cavity  113  may include a generally cylindrical portion and a conical end portion. The bolt head  112  may also include a beveled edge along the inner surface. 
     The flange  114  may be formed between the threaded shaft  118  and the bolt head  112 . The flange  114  may include a flat surface facing the washer  116  and the vehicle hub. The flange  114  may include a tapered external surface connecting to the external surface of the bolt head  112 . 
     The washer  116  may be an annular disc or ring located between the flange  114  and the threaded shaft  118 . The washer  116  may have a flat surface contacting the flange  114  and a curved or beveled surface that contacts the wheel, which may, for example, be an aluminum, alloy, or steel wheel. The washer  116  may distribute the load evenly along the wheel bore. The washer  116  may also help center the wheel bolt  110  within the wheel bore. 
     The threaded shaft  118  may match standard wheel bolt dimensions. For example, the threaded shaft  118  may have a diameter of 12 mm or 14 mm and a 1.5 mm right-hand thread. 
     The wheel bolt  110  may have strength and corrosion resistance properties. For example, the wheel bolt  110  may be formed of steel. The entire wheel bolt  110  may be coated with a zinc-aluminum composition film to prevent corrosion. In contrast to a chrome coating, the zinc-aluminum composition film may prevent corrosion without significantly decreasing strength. The film, however, may be unattractive compared to traditional chrome plating. 
     The wheel bolt cap  120  may be a plastic cap that covers the bolt head  112  when the wheel bolt  110  is installed in a vehicle hub to retain a wheel. The wheel bolt cap  120  may be formed of plastic material having desirable ornamental qualities. The wheel bolt cap  120  may also protect the wheel bolt  110  from road grime. Accordingly, the wheel bolt cap  120  may keep the wheel bolt  110  clean until a tool is used to engage the wheel bolt head  112  to remove the wheel bolt  110 . The wheel bolt cap  120  may include an end wall  122 , a side wall  124 , a skirt  126 , and a central member  130 . The end wall  122 , side wall  124 , and skirt  126  may define the external surface of the wheel bolt cap  120 . The central member  130  may be a retention feature that resides within the cavity  113  and may form a press fit with the internal surface of the bolt head  112 . 
     The end wall  122  may be a flat hexagonal plate or a gently curved dish. The external surface of the end wall  122  may be smooth or may include an ornamental design. The internal surface of the end wall  122  may include bumpers (not shown) to stop longitudinal movement of the cap  120  onto the bolt head  112 . For example, the bumpers may contact the edge of the bolt head  112 . 
     The side wall  124  may be a generally cylindrical member extending longitudinally from the end wall  122 . The external surface of the side wall  124  may be generally smooth. The side wall  124  may form an interference fit with the external surface of the bolt head  112 . In an aspect described in further detail below, the side wall  124  may include a plurality of longitudinal ribs that contact the external surface of the bolt head  112 . 
     The skirt  126  may be another generally cylindrical member extending from the side wall  124 . The skirt  126  may have a greater diameter than the side wall  124 . For example, the skirt  126  may have a diameter greater than or equal to the flange  114 . The skirt  126  may have a curved or beveled external surface. The skirt  126  may have a beveled interior surface to help guide the placement of the cap  120  onto the bolt  110 . In the exemplary embodiment, the skirt  126  adds rigidity (i.e., limits radial flex) to the side wall  124 . 
     The central member  130  may extend longitudinally from the interior surface of the end wall  122 . The central member  130  may be generally cylindrical. For example, the central member may have a cross-section that is circular, elliptical, or a regular polygon accounting for manufacturing tolerances. The central member  130  may have a diameter slightly less than the diameter of the cavity  113 . The length of the central member  130  may be slightly less than the depth of the cylindrical portion of the cavity  113 . The central member  130  may form an interference fit with the internal surface of the bolt head  112 . As will be discussed in further detail below, the central member  130  may include a plurality of longitudinal ribs that contact the internal surface of the bolt head  112 . 
       FIG. 2  illustrates a diagram  200  of a longitudinal cross-sectional view of another example wheel bolt  210  and the wheel bolt cap  120 . The wheel bolt  210  may be a lock bolt. The wheel bolt cap  120  is shown attached to the wheel bolt  210 . The wheel bolt cap  120  may be used with either the wheel bolt  110  or the wheel bolt  210 . 
     Similar to the wheel bolt  110 , the wheel bolt  210  may include a bolt head  212 , a flange  214 , a washer  216 , and a threaded shaft  218 . However, unlike bolt head  112 , bolt head  212  does not have a standard hexagonal shape configured to fit within a standard sized socket. Rather, bolt head  212  may have a circular external surface that is not used to provide torque to the wheel bolt  210 . Instead, the wheel bolt  210  may include a keyed portion  215 . The keyed portion  215  may include a pattern of slots and/or teeth that correspond to slots and/or teeth of a speciality socket configured to fit that specific locking wheel bolt  210 , or some subset of all similarly produced locking wheel bolts. The speciality socket may be placed over the bolt head  212  to engage the keyed portion  215 . The bolt head  212  also includes a cavity  213  defined by an inner surface of the bolt head  112 . The cavity  213  may reduce the total weight of the wheel bolt  210  compared to a wheel bolt having a solid bolt head. The cavity  213  may include a generally cylindrical portion and a conical end portion. The bolt head  212  may also include a beveled edge along the inner surface. 
     The flange  214  may be formed between the threaded shaft  218  and the bolt head  212 . The flange  214  may include a flat surface facing the washer  216  and the vehicle hub. The flange  214  may include or be connected to the keyed portion  215 . As illustrated, one side of the keyed portion  215  may include a tooth whereas an opposite side of the keyed portion  215  may include a slot, resulting in different radii along the cross-section. 
     The washer  216 , the threaded shaft  218 , and the wheel bolt  210  may have a similar configuration to the washer  116 , the threaded shaft  118 , and the wheel bolt  110 , respectively described above. 
     The wheel bolt cap  120  may operate with the wheel bolt  210  in a similar manner as with the wheel bolt  110 . The inner surface of the side wall  124  may form an interference fit with the external surface of the bolt head  212 . For example, the outer diameter of the bolt head  212  may be the same as the distance between flat outer surfaces of the hexagonal bolt head  112 . In an aspect, the length of the external surface of the bolt head  212  that contacts the side wall  124  may be shorter than the length of the external surface of the bolt head  112 . The central member  130  may form an interference fit with the internal surface of the bolt head  212  in a similar manner as with the internal surface of the bolt head  112 . 
       FIGS. 3-5  illustrate various stages of using an example tool  310  for removing the wheel bolt cap  120 . The tool  310  may be a tong-like device having two interconnected arms  312  having a toothed end  314 . The toothed end  314  may include an internal ramp surface and an internal shoulder. The wheel bolt  210  is shown inserted through a wheel  320  into the hub  330 . 
     At stage  300  shown in  FIG. 3 , the tool  310  may be placed such that the toothed ends  314  contact the end wall  122  of the cap  120 . The ramp surface may ride along the end wall  122  and may cause the arms  312  to spread. As the tool is moved toward the wheel  320 , the ramp surface may continue to ride along the side walls  124  and skirt  126  causing the arms  312  to spread farther. At stage  400  shown in  FIG. 4 , the toothed ends  314  are located outside of the skirt  126 . At stage  500  shown in  FIG. 5 , the toothed ends  314  may have moved past the skirt  126  and into a gap between the skirt  126  and the flange  214 . The shoulder of the toothed end  314  may contact the edge of the skirt  126 . The elastic force of the tool  310  may maintain the contact between the toothed end  314  and the skirt  126 , but additional force may be applied by squeezing the arms  312 . The cap  120  may be removed by pulling the tool  310  proximally to the left in the illustrated example. The cap  120  may be removed without rotating the tool  310 . In an aspect, the tool  310  may be free to rotate along a curved external surface of the skirt  126 . 
       FIG. 6  illustrates a bottom perspective view of the cap  120 .  FIG. 7  illustrates a cross-sectional view of the cap  120  transverse to the longitudinal axis. As illustrated, the side wall  124  may include a plurality of ribs  610 ,  612 ,  614  that may extend longitudinally. The ribs  610 ,  612 ,  614  may have a beveled edge extending from the beveled edge of the side wall  124 . The ribs  610 ,  612 ,  614  may also include beveled sides. The ribs  610 ,  612 ,  614  may be located at the center of a flat portion of the side wall  124 . Accordingly, the ribs  610  may contact a flat surface of the hexagonal bolt head  112  or any point on the outer surface of the circular bolt head  212 . As illustrated, the plurality of ribs may include three ribs. It should be appreciated that the number of ribs may be varied to provide a desired level of interference, which may increase or decrease the force required to insert or remove the cap  120 . 
     The cylindrical member  130  may also include a plurality of ribs  620 ,  622 ,  624 . Each of the ribs  620 ,  622 ,  624  may include a beveled leading edge that may help align the cylindrical member  130  with the cavity  113  or the cavity  213 . The ribs  620 ,  622 ,  624  may also include beveled sides. The ribs  620 ,  622 ,  624  may be evenly spaced around the circumference of the cylindrical member  130 . As illustrated, the plurality of ribs includes three ribs  620 ,  622 ,  624 . In an aspect, the ribs  620 ,  622 ,  624  are offset from the ribs  610 ,  612 ,  614 . In an aspect, for example, the offset may be approximately 30 degrees as measured by an angle between two lines extending from the center of the cap  120  and passing through corresponding ribs such as rib  610  and rib  620 . The offset between the ribs may reduce dependency between the interference caused by the external ribs  610 ,  612 ,  614  and the internal ribs  620 ,  622 ,  624 . For example, both the side wall  124  and the cylindrical member  130  may act as a hoop spring allowing distribution of stress. In contrast, if the ribs are aligned opposite each other, the opposing ribs may mutually increase interference with the bolt head sandwiched between the ribs. 
     As illustrated in  FIG. 7 , the end wall  122  may include bumpers  630 ,  632 ,  634 . The bumpers  630 ,  632 ,  634  may limit longitudinal movement of the cap  120  onto the wheel bolt  110  or the wheel bolt  210 . As the cap  120  is pressed onto the wheel bolt  110  or the wheel bolt  210 , the bumpers  630 ,  632 ,  634  may contact the edge of the bolt head  112  or bolt head  212 . The bumpers  630 ,  632 ,  634  may prevent the skirt  126  from contacting the flange  114  or flange  214 . The bumpers  630 ,  632 ,  634  may also limit the total interference between the ribs  610 ,  612 ,  614 ,  620 ,  622 ,  624  and the bolt head  112  or bolt head  212  by limiting the longitudinal surface of the ribs allowed to contact the bolt head  112  or bolt head  212 . For example, the bumpers  630 ,  632 ,  634  control the depth to which the bolt head extends into the cap  120 . Since the side walls  124  of the cap  120  are stiffer (i.e., allows less radial flex) near end wall  122  than in a middle of the side walls  124 , controlling the depth to which the bolt head extends into the cap  120  facilitates controlling the stress on the ribs  610 ,  612 ,  614 ,  620 ,  622 ,  624  and side walls  124 . 
     In an aspect, the wheel bolt cap  120  may be formed by molding. For example, known injection molding techniques may be used. Alternatively, any other plastic forming techniques may be used. The wheel bolt cap  120  may be removed from the injection mold in a finished state. The wheel bolt cap  120  may also undergo finishing procedures such as painting, coating, or polishing. 
     The plastic of the wheel bolt cap  120  may have a higher thermal expansion coefficient than the steel of the wheel bolt  110  or wheel bolt  210 . Accordingly, as the temperature increases the wheel bolt cap  120  may increase in size relative to the wheel bolt  110 ,  210 . As the wheel bolt cap  120  increases in size, the external ribs  610 ,  612 ,  614  may provide less interference with the external surface of the bolt head  112 ,  212 . The internal ribs  620 ,  622 ,  624 , however, may provide greater interference with the internal surface of the bolt head  112 ,  212 . Conversely, as the temperature decreases, the wheel bolt cap  120  may decrease in size relative to the wheel bolt  110 ,  210 . As the wheel bolt cap  120  decreases in size, the internal ribs  620 ,  622 ,  624 , may provide less interference with the internal surface of the bolt head  112 ,  212 . the external ribs  610 ,  612 ,  614 , however, may provide greater interference with the external surface of the bolt head  112 ,  212 . Accordingly, the combination of internal and external interference may reduce fluctuation in the total interference holding the cap  120  to the bolt head  112 ,  212 . 
       FIG. 8  illustrates a top plan view of the exterior of the wheel bolt cap  120 . As illustrated, the skirt  126  may be circular and the end wall  122  may be hexagonal. The side wall  124  may be the outer surface of a hexagonal prism corresponding to the end wall  122 . The location of the bolt head  212  is shown in dashed lines for reference. It should be appreciated that the shape of the external surfaces may be varied, for example, for ornamental purposes. Also, it should be appreciated that any corners may be rounded. 
     It will be appreciated that various implementations of the above-disclosed and other features and functions, or alternatives or varieties thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.