Abstract:
A heavy duty vehicle hubcap preferably made from a plastic material and having a sidewall, an end wall with a transparent window insert formed therein, and further including a radial mounting flange. The hubcap also includes an access port formed in the hubcap body sidewall and a vent plug removably positioned in liquid tight relation within the access port defined in the hubcap. Preferably, the hubcap is vented to permit passage of gas and vapor therethrough without permitting liquid to pass into the sealed region.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to vehicle components and manufacturing methods, and more particularly to hubcaps for truck, tractor, and semi-trailer wheel assemblies, and methods of making them. 
     BACKGROUND OF THE INVENTION 
     In automobiles, light trailers, and other light-duty applications, it is common for a wheel bearing assembly to be sealed relatively permanently for all or a good part of the service life of the assembly. Thus, automotive applications, permanently greased bearing assemblies are covered by opaque hubcaps (as opposed to decorative wheel covers which are sometimes incorrectly called hubcaps) which are never removed except for repairs, or for replacement of bearings and/or seals. In most cases, the bearings are permanently lubricated, or are lubricated by a supply of grease coming from another portion of the sealed assembly as a whole. 
     In the case of large, over-the-road truck tractors and semi-trailers, and other heavy-duty applications, however, the situation is different. Vehicles of these types have extended service lives both in terms of years and in terms of miles traveled. Wheel bearing assemblies are critical components of vehicles such as these. Most commonly, these wheel assemblies include a large, heavy-duty spindle and bearings engaging one or more rotatable parts, including a rotatable hub portion that in turns supports a brake drum and a removable wheel. In driven wheel applications, the bearings usually rest in the axle housing so that the driving axle is not subject to bending loads. In these cases, while the axle housing takes most or all of the load transmitted from the tires and wheels, and these bearing sets also include one or more oil or grease seals to retain the lubricant within the sealed region, and therefore also require hubcaps. 
     A number of years ago, many manufacturers and fleet operators, with the aid of bearing and seal suppliers, discovered that the life of ball or roller bearing type assemblies could be extended substantially by using oil rather than grease as the lubricant. Thus, the oil, although more fluent (less viscous) than grease, successfully addressed the problems of flushing dirt from the interfaces between metal parts. Modem oils are also formulated in such a way as to suspend entrained dirt and various other residues within the oil. In this way, as in automotive crankcases or other applications, the oil can be periodically drained and replaced with new, fresh oil, thus removing the grit and contaminants. This concept was brought to practical reality by the development of seals capable of handling low viscosity oils opposed to merely being able to impede leakage of semi-solid or gel materials such as greases. 
     Numerous prior art hubcap designs have been disclosed in U.S. Pat. No. 3,064,982 to Stephens, U.S. Pat. No. 3,316,022 to Isenbarger, U.S. Pat. No. 4,073,540 to Jackowski, U.S. Pat. No. 5,024,488 to Lindhuber et al., and U.S. Pat. No. 5,505,525, to Denton. To the extend effective, these prior art design had disadvantages. For example, of the prior art designs included a vent plug with internal pockets wherein oil tension lead to oil accumulation and the potential for light oil leakage. Another prior art vent plug design taught a venting section formed as “+”, i.e. “plus” shaped vent, having several wedges designed to permit passage of gas and vapor therethrough. Unfortunately, when in a non-vented mode, these wedges of the venting section failed to close properly and left voids therebetween to permit liquid, i.e. oil to escape from the sealed region and allow debris from outside to enter the voids thereby reducing lifespan of the hubcaps. 
     Therefore, an opportunity exists for an improve design of the vent plug that will prevent debris to enter into the hubcaps thereby increasing lifespan of the hubcaps and allowing oil not to flow away to the outside from the hubcap. 
     Another opportunity exists for an improve design of the vent plug that will open when pressurized to release the internal pressure at the same time allowing for minimal oil leakage when opened. 
     Still another opportunity exists for an improve design of the vent plug that is oil-impermeable and provide a positive mechanical barrier against the entrance of contaminants of all kinds. 
     SUMMARY OF THE INVENTION 
     While the invention is capable of being embodied in different forms, a description of a preferred embodiment thereof will be given wherein the application is that of a hubcap for a trailer or semi-trailer hub assembly for a semi-trailer truck. A hubcap assembly connected to a wheel hub surrounding a spindle surrounding a central axis extending through the wheel hub. The hubcap assembly includes a hubcap body having a sidewall extending to a mounting flange portions to connect with the wheel hub. An insert portion is mechanically interlocked with the sidewall of the hubcap body. The insert portion presents an opening. The hubcap assembly includes an elastomeric plug surrounding the central axis. The elastomeric plug is adaptable to be mechanically engaged with the insert portion and presents a cylindrical surface, an end surface, and a shoulder surface to mechanically engage the insert portion. 
     A vent portion of the elastomeric plug has a first section of a first thickness and a second section of a second thickness surrounding the first section. The vent portion extends from an idle position as the first section and the section are located along, i.e. coplanar with the end surface to maintain a substantially atmospheric pressure within said hubcap body and a venting position as the first section extends above the end surface thereby forming a funnel shape and stretching to form an opening to release the pressure out of the hubcap body. The first section elastically returns back to the idle position thereby keeping atmospheric pressure inside the hubcap body to eliminate leakage of fluids from the hubcap body and preventing debris and foreign object to enter the hubcap body. 
     An object of the invention is to provide an improved elastomeric plug for the hubcap body that is oil-impermeable and provides a positive mechanical barrier against the entrance of contaminants 
     Another object of the invention is to provide an improved hubcap which also includes an opening for replenishing or changing oil or other lubricant, with such opening being sealed by a plug that is resistant to unintentional removal. 
     Still another object of the invention is to provide an improved design of the vent plug that increases the lifespan of the hubcaps and allows oil not to flow away from the hubcap. 
     Still another object of the invention is to provide an improved design of the vent plug that opens when pressurized to release the internal pressure at the same time allowing for minimal oil leakage when opened. 
     The exact manner in which the foregoing and other objects and advantages of the invention are achieved in practice will become more clearly apparent when reference is made to the following detailed description of the preferred embodiments of the invention described in detail in the following specification and shown in the accompanying drawings, where in like reference numbers indicate corresponding parts throughout. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  is a perspective view of a truck having hubcaps on each wheel; 
         FIG. 1A  is a perspective view of the hubcap of  FIG. 1  and an improved vent plug connected thereto; 
         FIG. 2  is a perspective view of the improved hubcap of the invention, showing certain parts thereof in an exploded relation; 
         FIG. 3  is a cross sectional view of the vent plug; 
         FIG. 4A  is a partial perspective view of the central portion of the vent plug in a vented mode to permit passage of pressure, gas and vapor therethrough; 
         FIG. 4B  is a partial perspective view of the central portion of the vent plug in a non-vented mode to prevent contaminants and debris to pass into the sealed region from outside and preventing oil leakage; 
         FIG. 5A  is a partial perspective view of the central portion of a prior art vent plug in a vented mode, wherein venting section is formed as “+”, i.e. “plus” shaped vent to permit passage of gas and vapor therethrough; 
         FIG. 5B  is a partial perspective view of the central portion of the prior art vent plug, shown in  FIG. 5A , in a non-vented mode, wherein venting section are closed but still define voids therebetween to permit liquid to pass into the sealed region; and 
         FIG. 6  illustrates a diagram of a method of the present invention. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     While the invention is capable of being embodied in different forms, a description of a preferred embodiment thereof will be given wherein the application is that of a hubcap, generally indicated at  10  in  FIG. 1  and generally shown at  10  in  FIGS. 1A and 2 , for a trailer or semi-trailer hub assembly, generally shown at  12  in  FIG. 2  for a semi-trailer truck, generally shown at  13  in  FIG. 1 . 
     Thus, referring to the drawings in greater detail,  FIG. 2  shows a hubcap assembly generally designated  10  of the invention and showing the same to include a number of principal components including a hubcap body generally designated  14  and further showing a removable elastic vent plug generally indicated at  16  positioned within a window insert generally indicated  18  forming a part of the end wall of the hubcap  10 . 
     As shown in  FIG. 2 , a typical application of the hubcap  10  is shown. Here, the hubcap  10  is shown as being affixed in place over an end portion  22  of a wheel hub  24  so as to define a sealed region  25  which serves to receive and retain oil or other lubricant. The hub  24  includes a bearing counterbore  26  in which a tapered roller bearing assembly generally designated  28  is received and which is shown to include inner and outer races  30 ,  32 , and a cage  34  positioning a plurality of tapered bearing rollers  36 . 
     The inner race is kept in snug relation to the shoulder  38  of the counterbore  26  by a ring unit  40  backed by a spacer  42  against which a locking nut  44  is positioned. The nut  44  is threaded internally to engage cooperating threads  46  on the reduced diameter end portion  48  of a spindle generally designated  50 . 
     The hubcap assembly  10  includes a number of components, including a main body portion generally designated  56 , which in turn is shown to include tapered sidewalls  58 , the outer end wall, and an axially inner composite mounting flange  62 . The hubcap assembly  10  further includes the transparent window insert  18  to include a window center section  68 , a peripheral tongue  70  contained within and bonded to an inner margin  60  of the end wall  19 . The window insert  18  also includes an inturned inner flange  66  having an end face surface  64  joined to a tapered wall portion  72  that acts as a pilot or centering surface for the window insert or insert portion 18 . 
     As best illustrated in  FIGS. 2, 3, 4A and 4B , an elastomeric plug, i.e. a vent plug, generally shown at  80 , surrounds a central axis A of the spindle  50  and is adaptable to be mechanically engaged with the insert portion  18 . The vent plug  80  presents a cylindrical surface  82 , an end surface  84 , and a shoulder surface  86  to mechanically engage the insert portion  18 . 
     As best shown in  FIGS. 3, 4A and 4B , a vent portion, generally indicated at  90 , of the elastomeric plug  80 , includes a first section  92  with a first thickness  94  and a second section  96  with a second thickness  98  surrounding the first section  92 . The first thickness  94  is thinner than the second thickness  98 . An annular inclined  100  wall extends from the first section  92  to the second section  96  thereby diverging from the first section  92  to the second section  96 . 
     Alluding to the above, an inner wall  102  presents a diameter  104  that is wider than the diameter  106  of the second section  96 . As best shown in  FIGS. 4A and 4B , as pressure is accumulated inside the hubcap body  10 , the vent portion  90  extending from an idle position, shown at  FIG. 4B  as the first section  92  and the second section  96  are located along the end surface  84  to a venting position, shown in  FIG. 4A . In the venting position, the first section  92  extends above the end surface  84  thereby forming a funnel shape, generally indicated at  110 , and stretching to form an opening  112  to release the pressure out of the hubcap body  10  expanding radially away from the central axis A. 
     After pressure is released from the hubcap body  10 , the funnel shape  110  of the first section  92  elastically returns, i.e. is released back to the idle position of  FIG. 4B , as there is no pressure from the hubcap  10  thereby eliminating leakage of fluids, such as lubricants and oils from the hubcap body  10  and preventing debris and foreign object to enter said hubcap body. As the first section  92  returns from the venting position back to the idle position, the opening  112  closed or seals to prevent any ingress of fluids and contaminants into the hubcap body  10 . 
     Alluding to the above, the expansion of the first section  92  to the funnel shape  110  and exposure to the opening  112  and then release back to the idle position to seal the hubcap body  10  provides numerous advantages of a prior art vent plug design, generally shown at  200  in  FIGS. 5A and 5B .  FIG. 5A , for example, is a partial perspective view of a central portion  202  of the prior art vent plug  200  in a vented mode, wherein venting section is formed as “+”, i.e. “plus” shaped vent having four wedges  204  to permit passage of gas and vapor therethrough.  FIG. 5A  clearly shows an opening, generally indicated at  206 , defined between the wedges  204 .  FIG. 5B  is a partial perspective view of the central portion  202  of the prior art vent plug  200 , shown in a non-vented mode, wherein the wedges  204  of the venting section are closed but still define voids  208  therebetween to permit liquid to pass into the sealed region of the hubcap (not shown). This prior art design does not prevent complete sealing of the hubcap and allows debris and foreign object to enter the hubcap body. 
     A method of fabricating a hubcap assembly connected to a wheel hub surrounding a spindle surrounding a central axis extending through the wheel hub is generally shown at  300  in  FIG. 6 . The method includes the step  302  of forming a hubcap body having a sidewall extending to a mounting flange portions to connect with the wheel hub. The method  300  further includes the step  304  of mechanically interlocking an insert portion with the sidewall of the hubcap body. The step  306  is forming an elastomeric plug and mechanically engaging the elastomeric plug with the insert portion. 
     As the elastic plug is formed in the step  306 , a vent portion is being formed with a first section of a first thickness and a second section of a second thickness by forming the first thickness thinner than the second thickness. After the first section is formed, a needle is used to penetrate the first section to form a hole at the central axis, as shown in the step  308  of  FIG. 6 . The method  300  as set forth in claim  6 , including the step  310  of forming an annular inclined wall of the elastomeric plug that extends from the first section to the second section thereby diverging from the first section to the second section. 
     The method  300  further includes the step  312  of forming an inner wall of the elastomeric plug having a diameter that is wider than the diameter of the second section. The elastic plug can be formed by injection molding process but other fabrication processes can be used without limiting the scope of the present invention. The elastic plus is formed from polymeric and elastic materials without limiting the scope of the present invention. 
     It will thus be seen that the present invention provides a novel hubcap assembly and method for making the same, having a number of novel advantages and characteristics, including those referred to specifically herein and others which are inherent in the invention. A preferred form of hubcap and method of making it having been described in detail, it is anticipated that the variations in the described form of construction and method may occur to those skilled in the art, and that variations and modifications to the product and method may be made without departing from the spirit of the invention or the scope of the appended claims. 
     While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.