Patent Publication Number: US-2005126657-A1

Title: Failed nozzle relief for a mechanically sealed refueling nozzle in a filler tube

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to the filler tube for refueling a motor vehicle fuel tank of the type having a mechanical seal in the filler tube for sealing about a refueling nozzle upon insertion of the nozzle into the filler tube. Recent mandated limits on fuel vapor emission during refueling have required that the filler tube incorporate a seal to seal about the filler nozzle in a manner to prevent fuel vapor escaping to the atmosphere about the nozzle.  
      Current refueling nozzles incorporate an automatic shutoff feature for the nozzle to sense backup of the liquid fuel in the filler tube when the tank is full. However, if upon insertion, the nozzle is sealed in the filler tube and the nozzle shutoff fails to actuate, continued discharge of liquid fuel into the tank can create a positive pressure in the tank and result in rupture of either the tank or its attachments and conduits connected to the tank.  
      Accordingly, it has been desired to provide a way or means of bypassing the mechanical seal about the nozzle in the event of failure of the automatic nozzle shutoff during refueling.  
      Heretofore, fuel tank filler tube systems have employed an external bypass tube attached to the upper end of the filler tube with a one-way valve therein to provide a pressure relief and bypass around the mechanical nozzle seal. However, this arrangement has proven to be costly to manufacture in high volume production and has required provision for additional space around the filler tube within the vehicle body structure to accommodate the bypass tube. According, it has been desired to provide a way or means of effecting a bypass for a refueling nozzle seal in a tank filler tube in a manner which does not require additional cost or space upon installation.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention provides a pressure relief valve in a fuel tank filler tube of the type having a mechanical seal for sealing about the refueling nozzle upon insertion of the nozzle in the filler neck. The pressure relief valve of the present invention is disposed annularly about the mechanical nozzle seal and opens upon backup of liquid fuel into the filler neck in the event of failure of the automatic nozzle shutoff. Upon opening of the annular relief valve, fuel is permitted to flow around the nozzle seal and to discharge through the open end of the filler neck about the nozzle. In the presently preferred practice, the relief valve includes an annular valve member of having an annular flexible seal disposed thereon. The flexible seal may be mechanically attached to the valve member or may be molded thereon. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a cross-section of the upper end of a fuel tank filler tube with the invention installed thereon; and,  
       FIG. 2  is an exploded view of the components of  FIG. 1  without the filler tube. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to the drawings, an assembly of the invention in the upper end of a fuel tank filler tube is indicated generally at  10  and includes a filler tube  12  having an enlarged diameter portion  14  terminating at a proximal end in an outwardly extending flange  16  and having a retaining cup  18  for a filler tube cap (not shown) disposed on flange  16  by a corresponding outwardly extending flange  20  formed on the cup  18 . It will be understood that the lower or distal end of tube  12  (not shown) is adapted for connection to a fuel tank.  
      An annular insert  22  is received in the portion  14  of the filler tube; and, the insert  22  also has an outwardly extending flange  24  which is sandwiched between the flanges  16 ,  20  and is secured therein by any suitable expedient as, for example, weldment of cup  18 , insert  22  and the tube  12  to form a subassembly.  
      The insert  22  has an annular shoulder or offset portion  26  which is provided with at least one and preferably a plurality of circumferentially spaced apertures or openings  28  for providing bypass flow as will hereinafter be described in greater detail.  
      The insert  22  has another shoulder or annular flange  30  formed therein below or downstream of the shoulder  26 ; and, the shoulder  30  has disposed thereon an annular bead portion  32  of an annular lip seal  34  which is formed integrally with the bead  32  and extends downwardly therefrom tapering radially inwardly. The lip seal  34  is sized so as to seal about the outer periphery of a refueling nozzle upon insertion of a nozzle in the filler tube as shown in dashed outline in  FIG. 1  and denoted by reference numeral  36 .  
      A seal retaining collar or tubular insert  38  is disposed within the cup  18  and is tapered and configured to seal against the bead ring  32  of the tapered seal  34  thus retaining the seal compressed between insert  22  and the outer periphery of the insert  38  in addition to maintaining sealing contact of the bead ring  32  against the annular shoulder  30 .  
      The insert  38  may be retained in the cup  18  by any suitable expedient as, for example, deformation of the material and forming a convolution  40  thereon and by flaring the upper rim of the insert  38  outwardly over a correspondingly located inwardly extending convolution  37  formed in cup  18  or alternatively by weldment. Insert  38  has a plurality of slots or apertures  42  formed therein in the region above the seal  34  to provide bypass flow.  
      Disposed within the tube upper section  14  and in the region thereof between the flange  20  and the shoulder  26  is a one-way or pressure relief valve denoted generally at  44  which includes an annular support ring  46  which is moveable in the axial direction with respect to the tube  12  and which is biased downwardly, or in a direction toward the shoulder  26 , by a suitable spring arrangement  48  which may comprise a plurality of wave springs in series or other spring arrangement such as a coil spring. In the present practice of the invention, ring  46  is formed of metal; however, other suitable materials such as rigid plastic including glass filled polyamide may be used.  
      Ring member  46  has an annular flexible seal member  50  disposed thereon and secured thereto in the embodiment illustrated in  FIGS. 1 and 2 , mechanically by a plurality of tabs  52  disposed circumferentially thereabout which are each pulled through an aperture  53  correspondingly located in ring  46 . The annular seal member  50  preferably has a plurality of annular radially spaced lip surfaces  54 ,  56  which straddle at least one aperture  28  for sealing thereover. In an alternative arrangement the flexible seal  50  may be molded over ring  46 , as for example by insert molding. In the presently preferred practice the seal member  50  is formed of elastomeric material; however, other suitable materials including plasticized resin may be used.  
      It will be understood that in  FIG. 1  the position of the valve  44  is shown in the open position in solid outline and in closed position in dashed outline. Thus, with the refueling nozzle  36  inserted in the seal  34 , liquid fuel rising into the space between insert  22  and the filler tube  14  will permit flow of liquid through the at least one aperture  28  and through slots  42  around the nozzle and outwardly through the upper end of the cap retaining portion  18 . It will be understood that normally the valve  44  would be in the closed position with the fuel lips  54 ,  56  sealed against the upper surface of shoulder  26 . The present invention thus provides a simple low cost and compact way of providing a bypass valve in a fuel tank filler neck of the type having a seal about a refueling nozzle inserted therein to permit liquid fuel to escape therefrom in the event of failure of the nozzle to shut off.  
      Although the invention has hereinabove been described with respect to the illustrated embodiments, it will be understood that the invention is capable of modification and variation and is limited only by the following claims.