Patent Publication Number: US-6907865-B1

Title: Fuel tank assembly

Description:
TECHNICAL FIELD 
     The present invention relates to a fuel tank assembly and more particularly to a fuel pump subassembly of the fuel tank assembly for a motorcycle. 
     BACKGROUND OF THE INVENTION 
     Large vehicles, such as the automobile, have a typically fuel injected engine and a fuel pump subassembly mounted inside a fuel tank. The fuel tank is generally hidden from view and mounted to the undercarriage of the vehicle. Various penetrations and protrusions, such as a tank access hole for insertion of the fuel pump subassembly into the tank, are typically located at the top of the tank to minimize any opportunity of fuel leakage. A top mounted flange supports the fuel pump subassembly and covers and seals the access hole. Location of the flange and various protrusions projecting outward from the flange at the top of the tank protects the flange from abusive road conditions. Because the tanks are concealed by the undercarriage of the vehicle, any negative cosmetic impact of the top mounted flange is of no consequence. Moreover, any noise produced by the fuel pump is likely not to disturb the vehicle occupants because of the remote location of the fuel tank and because of the vibration dampening and noise absorbing characteristics of the plastic used to manufacture the tank. 
     For smaller recreational vehicles such as motorcycles, industry trends are turning away from the typical gravity feed carburetors and are leaning toward the use of fuel injection systems similar to larger vehicles. Location of the fuel pump inside the relatively small tank of a motorcycle would be preferred because it could reduce the number of fuel hose and electrical connections and also decrease fuel vapor emissions and the chance of fuel leakage into the surrounding environment while providing a modular design which simplifies assembly and reduces manufacturing costs. Unfortunately, the introduction of a fuel pump subassembly inside the tank of such a small recreational vehicle is difficult because: the fuel tank is visually exposed and typically mounted near the top of the recreational vehicle making cosmetic appearance and thus the location of the pump subassembly flange a concern; the tank is relatively small making pump placement difficult; and the tank is typically made of metal which contributes to the proliferation of pump noise. 
     Because the fuel tank is visually exposed in a motorcycle application, the tank is traditionally decorated thus contributing to a cosmetic theme of the motorcycle. Often, the shape or general appearance of the tank is identifiable to a particular manufacturer, thus having trademark value, thus making cosmetic alterations for the addition of a fuel pump subassembly undesirable. Moreover, the operator of the recreational vehicle or motorcycle is often located directly adjacent to the fuel tank, hence, the tank is preferably smooth, having minimal protrusions which could potentially cause injury to the operator or rider. For example, the fuel tank of a motorcycle is disposed generally between the legs of the rider. Consequently, the tank is preferably “tear-drop” in shape having the larger globe portion positioned toward the front of the motorcycle while tapering off and sloping downward toward the motorcycle seat creating a substantially smooth transition between the tank and the seat. For motorcycle applications, the only protrusion which could typically come between the ergonomically friendly fuel tank and the rider is the fuel filler cap. However, the cap is relatively low and smooth in profile and is located toward the forward top of the tank at the larger globe portion of the “teardrop.” The visually exposed placement of a flange, with associated fuel hoses and a wire harness, at the top of the fuel tank would not only crowd the filler cap, but would destroy the pleasing cosmetic appearance of the tank, expose the flange to possible damage and expose the rider to possible injury. 
     Moreover, the close proximity of the fuel tank to the rider makes the rider sensitive to noise emanating from the fuel tank. Because the motorcycle tank is traditionally made of steel, for strength and the adherence of paint, vibration induced noise caused by a running pump inside the tank is likely to be annoying to the rider. Furthermore, the running vibration characteristics of the motorcycle can be transmitted to the pump causing damage to pump components. 
     SUMMARY OF THE INVENTION 
     A cosmetically attractive fuel tank assembly preferably for a motorcycle application has a fuel pump subassembly inserted into the fuel chamber of the tank through a bottom access hole thus preserving the overall appearance, tradedress value and identifying characteristics of any specific manufacturer&#39;s tank. The flange of the fuel pump subassembly sealably covers the bottom access hole of the fuel tank. Various fuel pump subassembly components, such as a fuel pressure regulator, a fuel level sensor and an outlet fuel filter mount directly to the flange along with a tripod like bracket with three feet to support the fuel pump. The bracket is flexible and resiliently contacts an internal surface of a bottom wall of the fuel tank via a resilient pad which encases a rearward foot of the three feet. Preferably, the other two forward feet of the bracket engage threadably to the flange, yet are preferably spaced from the flange by respective vibration dampening members. Preferably, the fuel pump subassembly is preassembled prior to insertion into the tank through the access hole. The elongated shape of the subassembly and the relatively small size of the preferable motorcycle fuel tank requires that the fuel pump subassembly be rotated vertically within an imaginary plane until a rearward foot of a bridging portion of the bracket engages the internal surface, preferably at a bottom wall. As the flange seals to the bottom wall, a resilient bridging portion remains flexed and isolated from the flange and tank via the rearward pad and vibration dampening members. 
     Objects, features, and advantages of this invention include a fuel tank assembly for a fuel injected engine application which maintains traditional fuel tank exterior appearance, a reduction in fuel hose and electrical connections, a reduction in vibration amplitude prolonging the operational life of the fuel pump and reducing noise, and a more robust and module design simplifying manufacturing and reducing cost. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       These and other objects, features and advantages of the invention will be apparent from the following detailed description, appended claims, and accompanying drawings wherein: 
         FIG. 1  is a perspective view of a motorcycle having a fuel tank assembly of the present invention with a portion of a fuel tank broken away to show internal detail; 
         FIG. 2  is a perspective view of the fuel tank assembly with a portion broken away to show a fuel pump subassembly; 
         FIG. 3  is a perspective view of a bracket of the fuel pump subassembly. 
         FIG. 4  is an enlarged perspective view of the fuel tank; 
         FIG. 5  is a cross section view of a vibration dampening connection of the fuel pump subassembly, 
         FIG. 6  is a cross section view of a second embodiment of a vibration dampening connection; and 
         FIG. 7  is a cross section view of a third embodiment of a vibration damping connection. 
     
    
    
     DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , a motorcycle  10  has a fuel injected engine  12  which receives pressurized fuel from a cosmetically attractive fuel tank assembly  14 . A fuel pump subassembly  16  of the fuel tank assembly  14  is conveniently concealed inside a fuel tank  18  of the assembly  14  thus preserving the aesthetic appearance, shape and any trademark value pre-established by the manufacturer. The only exposed or viewable component of the fuel tank  18  is a conventional top mounted filler cap  20 , thus the tank  18  appears like a conventional fuel tank, however, the tank  18  of the present invention is not limited to flowing fuel via gravity to a combustion engine utilizing old carburetor technology. 
     Referring to  FIGS. 1-3 , the fuel tank  18  of the present invention is preferably made of metal for structural strength and superior paint adherence for cosmetic purposes. The fuel pump subassembly  16  is generally elongated in a non-linear fashion and shaped to fit within the relatively small confines of a fuel chamber  22  of the fuel tank  18  defined by an internal surface  24 . A bottom wall  26  of the tank  18  carries in-part the internal surface  24  and defines a bottom access hole  28  through which the fuel pump subassembly  16  is inserted. An external surface  30  of the metal fuel tank  18  is preferably painted in any variety of colors and designs enhancing the visual cosmetic appearance. 
     The tank  18  is generally rounded or “tear-drop” shaped having a substantially global portion  32  disposed toward the handle bars  34  of the motorcycle  10  and a converging portion  36  which converges rearward toward a seat  38  of the motorcycle  10  providing a smooth transition between the tank  18  and the seat  38  for rider comfort. 
     A substantially planar, and horizontally disposed, bottom support flange  40  of the fuel pump subassembly  16  has a peripheral edge  42  which carries a circumferentially extending and upward communicating groove  44  for seating a resilient O-ring  46  compressed against the external surface  30  of the bottom wall  26  at the global portion  32  of the tank  18  when assembled (as best shown is FIGS.  1  and  4 ). The O-ring  46  is fuel resistant and prevents the egress of fuel vapor, permeation, and/or gravity induced leakage of fuel out of the tank  18 . Various fuel pump subassembly components project substantially upward from an interior face  48  of the flange  40  and into the fuel chamber  22 . One of these components is a curved or arcuate bracket  50  which supports an elongated electric fuel pump  52  and projects generally from within the global portion  32  and into the converging portion  36  of the “tear-drop” tank  18 . Because of the unique shape, low profile, and small volume of the fuel tank  18 , the pump  52  is supported substantially horizontally along the top of the bracket  50  and is substantially disposed inside the converging portion  36  of the tank  18 . 
     The fuel pump  52  of the fuel pump subassembly  16  has a rearward inlet  54  communicating with a bag-type fuel filter  56  capable of filtering out particles of approximately greater than thirty microns to protect the pump  52 . The filter  56  generally touches the internal surface  24  of the tank  18  at the rearward-most region of the converging portion  36 . This touching of the internal surface  24 , which includes the bottom wall  26  and sidewalls  27 , promotes the wetting or capillary action of the filter  56  for providing a constant supply of fuel to the pump inlet  54  even when portions of the filter  56  are not submerged in the liquid fuel. This partial exposure of the filter  56  to air is caused by excessive movement of fuel in a small tank, characteristic of recreational vehicles. Moreover, the filter  56  is conveniently located at the rear of the fuel tank  18  which is likely to see elevated levels of fuel during fast accelerations which is often characteristic of motorcycles  10 . 
     The thirty micron filtered fuel flows out of the pump  52  in a super-atmospheric pressure condition via a fuel outlet or tube  58  disposed at a forward end  59  of the pump  52  opposite the inlet  54 . The tube  58  projects generally forward from the pump  52  and downward to engage an upward unitarily projecting union  60  of the flange  40  which defines a channel (not shown) for flowing the fuel into an outlet filter  62 . The outlet filter  62  projects unitarily upward from the interior face  48  of the flange  40  and filters approximately ten micron or greater particulate out of the super-atmospheric fuel to protect an upstream pressure regulator  64  of the fuel pump subassembly  16  and to protect the fuel injectors of the combustion engine  12 . Similar to the outlet filter  62 , the pressure regulator  64  projects upward from the bottom flange  40  and receives flowing fuel from the adjacent outlet filter  62  via a channel (not shown) integral to the flange. From the pressure regulator  64 , fuel flows out of the tank  18  and through the bottom flange  40  via a nozzle or outlet  66  that projects unitarily downward from an exterior face  68  of the flange  40 . 
     The bottom flange  40  also internally supports a fuel level sensor  70  via the bracket  50  and an integral electrical connector  72  which extends through the flange  40  and electrically connects to an internal wiring harness  74  for providing electric power to the fuel pump  52  and for carrying an electric signal from the fuel level sensor  70 . 
     Referring to  FIGS. 2 and 3 , the bracket  50  is designed to resiliently support the fuel pump  52  within the fuel tank  18  and to isolate vibrations, or prevent transmittance of vibrations and noise, between the fuel tank  18  and the pump  52 . This isolation reduces pump induced vibration which could otherwise be transmitted and magnified by the steel fuel tank  18  as noise thus creating an annoyance for the adjacent rider. Moreover, the bracket  50  reduces transfer of vibrations induced by the running engine  12  and transmitted through the fuel tank  18  thus prolonging the useful operating life of the fuel pump  52 . 
     The arcuate bracket  50  is preferably made of a stamped low carbon steel for resiliency and strength, and is generally tripod-like having a resilient mid-bridging portion or elongated ban  75  which carries a concave profile formed by a bottom side  76  that faces generally downward toward the tank bottom wall  26 . An opposite convex or top side  78  of the ban  75  substantially extends longitudinally with, and engages, the elongated pump  52  disposed above it. A pair of straps  80 , preferably made of plastic, engage the pump  52  to the bracket  50  generally preventing lateral and upward movement of the pump  52  with respect to the bracket  50 . Each strap  80  generally extends perpendicular to the ban  75  and wraps about the ban and the pump  52 . The plastic straps  80  are spaced longitudinally apart from one another with respect to the steel ban  75  and pump  52  in order to secure circumferentially about each end of the pump  52 . 
     A pair of forward fingers  79  prevent forward or longitudinal movement of the pump  52  with respect to the bracket  50 , and a second pair of rearward fingers  81  prevent rearward movement. Each finger of each pair of fingers  79 ,  81  is cantilevered laterally outward from opposite edges  83 ,  85  of the ban  75 . The lateral projection of each finger is bent slightly upward forming a generally concave saddle or seat  87  for each pair which conforms and seats to the cylindrical shape of the fuel pump  52 . Each finger of the forward fingers  79  project longitudinally forward to an upward bent distal end  89  which catches the forward end of the pump  52  preventing forward pump movement. Likewise, each finger of the rearward fingers  81  project longitudinally rearward to an upward bent distal end  91  which catches the rearward end of the pump  52  preventing rearward pump movement. 
     Referring to  FIGS. 2-5 , a vibration absorbing connection  93  between the flange  40  and the bracket  50  utilizes a pair of forward feet  82  of the bracket  50  which project substantially forward from a forward end of the bracket ban  75 . The feet  82  attach to respective stanchions  84  of the connection  93  that project unitarily upward from the interior face  48  of the preferably plastic flange  40 . Each stanchion  84  has a threaded blind bore  86  which threadably receives a male fastener or bolt  88  to secure the respective foot  82  to the flange  40 . A vibration damping member or grommet  90  spaces the foot  82  of the bracket  50  axially away from the stanchion  84 , and radially and axially away from the male fastener  88 . The grommet  90  is made of a resilient fuel resistant rubber-like material and can thus absorb vibrations transmitted to and from the fuel pump  52 . Preferably, the grommet  90  is pre-mounted or press fitted into an over-sized bolt hole  94  defined by an inner edge  92  of each foot  82 . When fully mounted, the circumferential edge  92  seats into a radially outwardly open circumferential groove  96  carried by the grommet  90 . 
     Projecting rearward from an opposite end of the ban or bridging portion  75  is a third or rearward foot  98  which is engaged directly to a vibration absorbing pad or grommet  100 . When the fuel tank assembly  14  is fully assembled, the steel bridging portion  75  is shaped to resiliently bias the rearward foot  98  and grommet  100  against the internal surface  24  of the bottom wall  26  to reduce vibration and eliminate resonating frequencies by eliminating any possibility of a clearance or space developing between the rearward foot  98  or grommet  100  and the bottom wall  26 . Thus, with the resilient ban  75  placed under continuous stress, the foot  98  and grommet  100  are in continuous contact with the bottom wall  26  regardless of surrounding influences such as vibration and without the need for a fastening device or structure. Similar to the forward feet  82 , the rearward foot  98  is spaced from the internal surface  24  by the resilient grommet  100  pressfitted into a hole  101  carried by the foot  98 . 
     Referring to  FIG. 3 , a substantially horizontal shelf or sub-bracket  103  projects generally laterally outward from the edge  85  at a substantially vertical portion of the ban  75 . The shelf has a hole  105  which receives and secures the fuel level sensor  70 . Because the fuel level sensor  70  secures to the bracket  52  and not directly to the flange  40 , the sensor  70  is not directly exposed to potentially harmful vibrations emanating from the combustion engine  12 . 
     The fuel pump subassembly  16  is preferably pre-assembled prior to insertion into the fuel tank  18  through the bottom access hole  28 . During insertion, the elongated fuel pump  52  is substantially positioned vertically. As the inlet filter  56 , bracket  50  and fuel pump  52  are inserted through the access hole  28 , the subassembly  16  is simultaneously rotated approximately ninety degrees so that the leading inlet filter  56  disposed toward the rear of the fuel pump subassembly  16  does not hit the close confines or internal surface  24  at the top of the tank  18 . This insertion, and simultaneous rotation places the filter  56 , bracket  50  and pump  52  into the close confines of the converging portion  36  of the tank  18 . As the peripheral edge  42  of the flange  40  and O-ring  46  seal against the external surface  30  of the bottom wall  26 , the grommet  100 , which is pre-fitted to the rearward foot  98  of the bracket  50  presses resiliently against the internal surface  24  of the bottom wall  26 , and the bridging portion  75  resiliently flexes assuring continuous contact between the grommet  100  and the tank  18  and assuring unobstructed sealing between the flange  40  and the tank  18 . 
     Referring to  FIG. 6 , a second embodiment of a connection  93 ′ is illustrated. Connection  93 ′ has a vibration absorbing member  90 ′ which is similar to a resilient stanchion extension projecting upward. Member  90 ′ is engaged between and spaces apart a forward foot  82 ′ and a rigid flange stanchion  84 ′. A threaded fastener  88 ′ has an enlarged head embedded into the vibration absorbing member  90 ′ during the molding process of the rubber member, and threadably attaches to the stanchion  84 ′ as a single part. Unlike the first embodiment, the member  90 ′ of the connection  93 ′ has a second embedded threaded fastener  102  which projects upward from the member  90 ′ and extends through a hole  94 ′ of the foot  82 ′. The fastener  102  and member  90 ′ are secured to the foot  82 ′ via a nut  104  engaged threadably to the fastener  102 . Member  90 ′ has a void  106  which promotes flexibility of the connection  81 ′. Because the fasteners  88 ′,  102  are independent from one another, torquing of either threaded fastener  88 ′,  102  during assembly will not effect the resiliency of the vibration absorbing member  90 ′. 
     Referring to  FIG. 7 , a third embodiment of a connection  93 ″ is illustrated. Each connection  93 ″ has two rigid stanchions  84 ″ bridged by a vibration absorbing member  90 ″ which is secured to each stanchion  84 ″ by respective threaded bolts  88 ″. A foot  82 ″ is fastened directly to an upward projecting mound or prominence  108  having a hole  110  orientated concentrically below a hole  94 ″ of the foot  82 ″. A threaded fastener or bolt  102 ″ extends through the holes  94 ″,  110  and threads to a nut  104 ″ orientated directly above the foot  82 ″. Similar to the second embodiment, torquing down upon any one fastener during pre-assembly will not substantially effect the vibration absorbing characteristics of the member  90 ″. 
     While the forms of the invention herein disclosed constitute presently preferred embodiments many others are possible, it is not intended here in to mention all of the possible equivalent forms or ramifications of the invention, it is understood that the terms used herein are merely descriptive rather than limiting and that various changes may be made without departing from the spirit or scope of the invention as defined by the following claims.