Abstract:
An automatic tire inflation system in which air for rotating tires is transmitted through an air connection between an air supply and each of the tires. In particularly, the present invention is directed to a hubcap structure housing a removable plug which provides a simple way to check or replenish the lubricant in the hubcap and allows maintenance or replacing of the wear parts in the rotary air connection without disassembling the tire inflation system.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention is directed to improvements in an automatic tire inflation system in which the air for rotating tires is transmitted through an air connection between an air supply and each of the tires. In particularly, the present invention is directed to a hubcap structure which provides a simple way to check or replenish the lubricant in the hubcap and allows maintenance or replacing of the wear parts in the rotary air connection without disassembling the tire inflation system.  
         [0002]     The wheel assembly on a truck trailer requires a hubcap at the end of the assembly to retain lubrication in the hubcap compartment for lubricating the wheel bearings as best seen in U.S. Pat. No. 5,584,949. When the vehicle includes an automatic tire inflation system, which may have a pressure of 110 psi, an air leak in the connection system, which passes through the hubcap compartment, can blow out a conventional air vent plug resulting in the loss of lubricant from the wheel bearings and their consequential failure and expensive damage. While the system of the &#39;949 patent is satisfactory for checking and replenishing the lubricant in the hubcap compartment, any repair on the pneumatic rotary union requires removal of the hubcap as the air lines extend through the sides of the hub cap. This requires disconnection of the air lines, is time-consuming, requires tools, and some expertise.  
         [0003]     Another prior art system, which will be described in greater detail later, is illustrated in  FIG. 1  in which the air connection screws into the center of the hubcap and supports one end of the rotor or rotating member of the pneumatic rotary union. While the air connection or through tee fitting can be removed, it requires disconnection of the air hoses leading therefrom to the tires. In addition, the opening for the tee is not sufficient for satisfactorily adding and inspecting lubricant in the hubcap and therefore a side seal plug is required in the hubcap. This requires additional tools and requires that the rotation of the wheel is positioned so that the wheel plug is upright for filling. This fill method requires tools and does not allow for checking lubrication levels.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     The present invention is directed to a an easy maintenance automatic tire inflation system in which the lubricant in the hubcap may be checked or replenished through a removable center plug in the hubcap without the use of tools. In addition, both the stator and rotor, the stationary and rotating parts of the pneumatic rotary union, can be removed and repaired without disconnecting the hubcap. Furthermore, the structure of the hub is designed to direct lubricant away from the air vents which are positioned in the plug.  
         [0005]     One object of the present invention is the improvement of an improved air inflation system having a pneumatic rotary union including a first stationary part and a second rotatable part. A hubcap is provided having an opening coaxially aligned with the rotary union, a plug is releasably supported in the opening, said plug including a support opening coaxially aligned with the rotary union, said plug including one or more air vents positioned outside of the support opening, and said support opening supporting a through tee and a vent shield covering the outside of the air vents supporting one end of the rotatable part of the rotary union. The hubcap opening is of a size for adding and visually inspecting lubrication level and for removing both the rotor and stator of the rotary union through the hubcap opening without removing the hubcap.  
         [0006]     A still further object of the present invention is wherein the plug consists of a rigid material for providing a firm support for the through tee, and said plug includes a head at one end for abutting the outside of the hubcap, and an extension extending through and beyond the inside of the hubcap opening and terminating in a second end spaced from the hubcap for diverting lubricant away from the air vents, and a circular seal surrounding the plug intermediate the first and second ends sealing against the inside of the hubcap, and releasably holding the hubcap in position in the hubcap opening.  
         [0007]     Yet a still further object of the present invention is wherein the plug includes surfaces exposed to the interior of the hubcap and the surfaces are positioned to direct lubrication in the hubcap away from the air vents.  
         [0008]     A still further object is wherein the surfaces include an interior surface outside of the air vents, said interior surface tapering outwardly towards the second end of the plug for centrifugally directing lubrication away from the air vents while the hubcap is rotating. In the preferred embodiment the interior surface includes a first and a second outwardly directed tapered surfaces.  
         [0009]     Another object of the present invention wherein the plug includes an exterior surface adjacent the second end of the plug which includes a recess around the exterior surface of the plug for directing lubrication away from the air vents while the hub cap is static.  
         [0010]     A further object is wherein the outside of the head of the plug includes a knurled surface for ease of removing the plug from the hubcap opening.  
         [0011]     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized that such equivalent constructions do not depart from the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:  
         [0013]      FIG. 1  is an elevational view, in cross section, of a prior art rotary air connection in a tire inflation system;  
         [0014]      FIG. 2  is an elevational view, in cross section, of the present invention;  
         [0015]      FIG. 3  is an enlarged elevational view, in cross section, of the removable or popout plug of the present invention;  
         [0016]      FIG. 4  is an elevational end view of the plug of  FIG. 3 ; and  
         [0017]      FIG. 5  is an exploded perspective view of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     Referring to  FIG. 1 , a prior art automatic tire inflation system known as MTIS system manufactured by Pressure Systems International of San Antonio, Tex., is shown. The reference numeral  100  generally indicates the rotary air connection for supplying air from an air supply on a vehicle in an automatic tire inflation system for a vehicle to rotating tires. The numeral  112  generally indicates one axle or spindle, a hubcap  114  is provided at each end of the axle  112  for retaining lubricant in the wheel bearings, and an air supply  116  either directly in the axle  112  or through an interior conduit (not shown) in the inside of the axle  112  supplies air to the rotary air connection through the inside of the axle. A pneumatic rotary union generally indicated by the reference numeral  120  is supported and positioned in the center of the axle  112 , such as by force fit plug  220 , but sealingly engages the interior of the axle  112  by seal  124  as air is injected directly into the inside of the axle  112 . The rotary union  120  has a first stationary part or stator  128  having a passageway  136  therethrough. The passageway  136  is in communication with the air supply  116 . A first resilient rotary seal  138  is supported in the passageway  136  and encircles the passageway  136 . The union  120  includes a second rotatable part or rotor including a tubular member  142  having a first end  144  and a second end  146 . The second end  146  is coaxially extendible through and is longitudinally and rotationally movable in the passageway  136  and sealably engages the rotary seal  138  and is in communication with the air supply  116 . The first end  144  of the tubular member  142  is sealably connected to the air connection or through tee  152  on the hubcap  114  through a seal  150 . The air connection  152  or through tee is provided on the hubcap  114  for connection to the tire or tires through air hoses (not shown) at the end of the axle  112 . The end  144  of the tubular member  142  includes a shoulder which includes a bearing  101 . In operation, air is supplied through the stationary part  128  of the rotary union  120 , through the rotatable member  142 , the through tee  152  and to the tires. The system  100  includes the air pressure supply  116  and a suitable warning system such as a flow switch  32   a  and a warning indicator light  34   a  in the event of loss of air pressure. The hub cap  114  also includes a plurality of air vent holes  160  and a yieldable rubber vent shield  162  normally closing the vents  160  but opening and allowing the escape of air in the event of a leak from the system  100  into the inside compartment of the hubcap  114 . The shield  162  is supported from the through tee  152  which is threadably secured by threads  164  to the wall of the hubcap  114  and supports one end of the rotatable member or rotor  142 . Lubrication to the inside of the hubcap  114  is accomplished by a side fill plug  170  on the outer diameter of the hubcap  114 . This fill method requires tools for unscrewing the plug  170  and does not allow for checking lubrication levels. While hubcap  114  includes a sight glass  172 , it is usually caked up with lubricant and is not usable. In addition, if the position of the truck is such that the plug  170  is not an up position, then the vehicle will have to be rotated to bring the plug  170  into an up position for replenishing the lubricant supply. On a plurality of tires on a vehicle, this can be time-consuming. The through tee  152  can be unscrewed from the hubcap  114 , after disconnecting air hoses to the tires (not shown) and remove the rotor  142  for repair. However, the stationary part or stator  128  cannot be removed without removing the hubcap  114 .  
         [0019]     Referring now to  FIGS. 2, 3 ,  4  and  5 , the reference numeral  10  generally indicates the rotatable air connection of the present invention for supplying air from an air supply on a vehicle in an automatic tire inflation system for a vehicle to the rotating tires (not shown). The numeral  12  generally indicates one axle or spindle, a hubcap  14  is provided at each end of the axle  12  for retaining lubricant to the wheel bearings (not shown) and an air supply  16 , either directly in the axle  12 , or through an interior conduit (not shown) in the inside of the axle  12  for supplying air to the rotary connection through the inside of the axle. A pneumatic rotary union generally indicated by the reference numeral  20  is supported and positioned in the center of the axle  12 , such as by force fit plug  22 , but sealingly engages the interior of the axle  12  by a seal  24  if air is injected directly into the inside of the axle  12 . The rotary union  20  has a first stationary part  28  threadably secured into the center of the plug  22  by threads  23 , a passageway  36  therethrough and a hexagonal head  37 . The passageway  36  is in communication with the air supply  16 . A first resilient rotary seal  38  is supported in the passageway  36  and encircles the passageway  36 . The union  20  includes a second rotatable part or rotor including a tubular member  42  having a first end  44  and a second end  46 . The second end  46  is coaxially extendible through and is longitudinally and rotationally movable in the passageway  36  and sealably engages the rotary seal  38  and is in communication with the air supply  16 . The first end  44  of the tubular member  42  is sealably connected to the air connection or through tee  52  on the hubcap  14  through a seal  50 . The air connection  52  or through tee is provided on the hubcap  14  for connection to the tire or tires (not shown) at the end of the axle  12  through air hoses  55  and  57  ( FIG. 5 ). The end  44  of the tubular member  42  includes a shoulder which includes a bearing  11 . In operation, air  16  is supplied through the stationary part  28  of the rotary union  20 . The inflation system  10  includes any suitable warning system such as a flow switch  32  and a warning indicator light  34  for indicating when the air pressure is leaking. The above description is generally disclosed in U.S. patent application Ser. No. 10/186,951 entitled “Rotary Air Coupling Connection with Bearing for Tire Inflation System,” which is herewith incorporated by reference.  
         [0020]     In the present invention the hubcap  14  includes an opening  58  ( FIG. 5 ) coaxially aligned with the rotary union  20 . A plug  60  is releasably supported in the opening  68  and said plug includes a threaded support opening  62  coaxially aligned with the rotary union  20 . The plug  60  includes one or more air vents  64 , here shown as six, positioned outside of the support opening  62 . The support opening  62  supports the through tee  52  in the opening  62  and in turn supports one end of the rotatable part  42  of the rotary union  20  and a vent shield  66  covering the outside of the air vents  64 . The hubcap opening  58  is of a size for adding and visually inspecting lubrication level in the inside of the hubcap  14  and for passing a socket wrench for engaging the head  37  of the stator member  28  for removing the stator member  28  through the hubcap opening  58  without removing the hubcap  14 . For example only, the opening  58  may be 1.625 inches in diameter. The plug  60  consists of a rigid material for providing a firm support for the through tee  52  and for example only may consists of a hard plastic such as Delrin. The plug  60  includes a head  68  at a first end for abutting the outside of the hubcap  14  and an extension  70  extending through and beyond the inside of the hubcap  14  and terminating in a second end  72 . A circular seal  74  surrounds the plug  60  intermediate the first end  68  and the second end  72  and seals against the inside of the hubcap  14  and releasably holds the plug in position in the hubcap opening. However, the plug  60  may be easily removed from the opening  58  and a knurled surface is provided on the head  68  for that purpose. In addition, the plug  60  may be blown out the opening  58  in the event the air vents fail to exhaust the air. And if the plug  60  is blown out of opening  58  it will not be lost on the highway as occurs with conventional vent plugs since it is secured to lines  55  and  57  by the through tee  52 .  
         [0021]     As best seen in  FIG. 3 , the plug  60  includes an extension  70  and surfaces exposed to the interior of the hubcap  14  which are positioned to direct lubrication in the hubcap away from the air vents  64  so that if oil passes through vent holes  64  of the plug  60  it may be centrifugally ejected onto the face of the hubcap  14 . Also in the event of a leak in the air pressure system less of the lubricant may be blown out of the hubcap  14 . The surfaces include an interior surface  76  outside of the air vents  64  and the interior surface  76  taper outwardly towards the second end  72  of the plug  60  for centrifugally directing lubrication away from the air vent  64  when the hubcap is rotating. The interior surface  76  may include a second outwardly directed tapered surface  78 .  
         [0022]     In addition, the plug  60  includes an exterior surface  80  adjacent the second end  72  of the plug  60  which includes a recess surrounding the exterior surface for directing lubrication away from the air vent  64  while the hubcap is static. For example, the overall length of the plug  60  may be one inch and the diameter of the head may be two inches. The taper  78  may be greater than the taper  76  and by way of example may be 45°.  
         [0023]     Referring now to  FIG. 5 , the combination of the through tee fitting  52  and plug  60  may be popped out or manually removed from the opening  58  without disconnecting the air hoses  55  and  57 . Lubricant on the interior of the hubcap  14  may be replaced and visually observed. If desired, the plug  60  may be unscrewed from the through tee fitting  52 , the lines  55  and  57  removed, and the rotor  42  repaired. Additionally, stator  28  may be threadably removed from the plug  22 . Thus, all of the wear parts in the rotary union  52  may be inspected, repaired and replaced without removing the hubcap  14 . Thus, a minimum of tools, a minimum of expertise, and a minimum of time and expense are required to perform minor repairs on the wear portions of the system  10  of the present invention.  
         [0024]     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.