Abstract:
A method of forming a filler tube includes forming a funnel insert, forming a funnel portion in a first end of a filler tube, and joining the funnel insert and the funnel portion of the filler tube. The funnel portion includes a transition portion configured to induce a swirl to passing fuel for venting vapors from the gas tank during fuel filling. A fuel filler tube assembly includes the funnel portion including a tubular body defining a larger inlet and a smaller outlet, the position of the inlet relative the outlet and an internal configuration of the tubular body therebetween inducing a swirl to inventing vapors from fuel flowing through the tubular body. The larger inlet receives a funnel insert including a nozzle opening positioned to cooperate with the internal configuration of the tubular body.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a fuel tank system for an automobile and, in particular, to an improved filler tube assembly.  
       BACKGROUND OF THE INVENTION  
       [0002]     Reducing gasoline vapor loss in fuel tank systems is becoming increasingly important in the automobile industry. A solution to this problem has been to reduce the diameter of an outlet end of a fuel tank filler neck relative an inlet end. While this approach has achieved some success, the success has been limited because as the diameter of the filler neck is decreased, the resistance to gasoline flow is increased. This increased resistance has caused other problems, notably pressure build up in the filler neck, often causing the fuel nozzle to shut off before the fuel tank is full.  
         [0003]     Permeability of materials from which the filler tube assembly is manufactured also presents another design issue because the fuel vapors may diffuse through the fuel tank system components; various types of mild steels, for example, permit fuel vapor diffusion. Such fuel vapor diffusion further increases as steel components corrode over time.  
         [0004]     A manufacturing issue with current filler neck designs is the method by which the diameter of inlet and of the filler neck is increased relative the diameter of the outlet end in order to provide a sufficient diameter to accept a gas nozzle during refueling. While filler necks are often made by a process of repeated reductions and expansions of a seamed, welded tube, this mechanical process structurally weakens the tube, resulting in an increasing tendency for the tube to leak at the seam.  
         [0005]     To address this issue, manufacturers have begun using a seamless tube, which addresses the seam-leak problem but requires mechanically joining the outlet end of the filler neck to a separate filler tube and coupling a nozzle retainer. Such prior art attempts will include U.S. patent application Ser. No. 09/454,103, now U.S. Pat. No. 6,330,893; U.S. patent application Ser. No. 09/998,113, now U.S. Pat. No. 6,588,459; and U.S. patent application Ser. No. 10/615,485, filed Jul. 8, 2003; each of which is incorporated herein by reference. While these designs are improvements, such a three-piece fuel filler tube assembly is relatively expensive to manufacture and assemble and necessarily requires mechanical joints between the filler neck and filler tube, as well as between the nozzle retainer and the filler neck. Any joint in a fuel filler tube assembly creates the possibility for vapor loss or fuel leaks through a defect or corrosion.  
         [0006]     Moreover, with the necessity to assemble the parts post-manufacturing of the individual parts, variability in part dimensions—for example, the joints between the filler neck outlet and the filler tube and between the nozzle retainer and filler neck—as well as the quality of any sealing surfaces, can lead to an inferior product. Similarly, inconsistency in the orientation of features of the filler tube assembly, for example, thread orientation relative a fuel cap sealing surface or nozzle retainer orientation relative filler tube features, can lead to defective fuel filler tube assemblies through mistakes in the assembly process.  
       SUMMARY OF THE INVENTION  
       [0007]     A method of forming a filler tube assembly includes forming a funnel insert, forming a funnel portion at a first end of a filler tube, and joining the funnel insert in the funnel portion of the filler tube. The funnel portion is configured to include a transition portion for inducing a swirl to passing fuel, whereby vapors may be vented from the gas tank during fuel filling. The configuration includes forming an inlet at one end of the funnel portion and forming an outlet at the opposite end of the funnel portion. An axis of the inlet is offset from the axis of the outlet.  
         [0008]     The method may further include forming a sealing surface above the inlet opening to the funnel insert, perhaps by rolling over an edge defining the inlet opening. The funnel insert may further include threads formed integrally therein, the threads adapted to engage a fuel cap for sealing the fuel tank system from the environment.  
         [0009]     The filler tube is preferably formed by cutting a length of tube stock to form the filler tube. The funnel insert preferably includes an integrally formed nozzle receptor.  
         [0010]     An end of the filler tube opposite the funnel insert may be joined to a fuel tank. Further, opposite ends of a vent tube may be joined to the funnel portion of the filler tube and the fuel tank, respectively, in order to provide ventilation for the fuel tank system.  
         [0011]     A fuel filler tube assembly according to the invention includes a funnel portion of a filler tube including a tubular body defined in a larger inlet and a smaller outlet, the position of the inlet relative the outlet and an internal configuration of the tubular body between the inlet and the outlet inducing a swirl to inventing vapors from fuel flowing through the tubular body. The larger inlet receives a funnel insert including a nozzle opening position to cooperate with the internal configuration of the tubular body. The internal configuration of the tubular body includes a tapered section of the tubular body having an elliptically shaped junction between a first portion of the tubular body including the inlet end and a second portion of the tubular body including the outlet. The elliptically shaped junction lies on a plane inclined to be angled to an axis of at least one of the inlet and the outlet. The filler tube and the funnel insert are preferably formed from a seamless tube.  
         [0012]     The filler tube assembly may include a sealing surface formed integrally about an inlet opening of the funnel insert. The funnel insert may further include integrally formed threads for receiving the fuel cap.  
         [0013]     The filler tube assembly may include a vent tube connected to the filler tube. Further, the vent tube may be connected to a fuel tank that is also connected to the filler tube.  
         [0014]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0016]      FIG. 1  is a schematic view of a fuel tank system according to the invention;  
         [0017]      FIG. 2  is an exploded perspective view of the filler tube assembly according to the invention;  
         [0018]      FIG. 3  is a partial side view of a filler tube assembly according to the invention;  
         [0019]      FIG. 4  is a sectioned side view of the filler tube assembly according to the invention;  
         [0020]      FIG. 5  is a schematic illustration of the filler tube assembly according to the invention;  
         [0021]      FIG. 6  is a schematic illustration of a method of forming threads in the filler tube assembly; and  
         [0022]      FIG. 7  is a schematic illustration of another method of forming threads in the filler tube assembly.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0024]     With reference to  FIGS. 1 and 2 , a fuel tank system  10  generally includes a filler tube assembly  12 , a fuel tank  14 , and a fuel cap  16 . The fuel tank system  10 , which is supported by an automobile body  22 , may further include a ventilation system  18 , which is illustrated generally as a vent tube  20  extending between the filler tube assembly  12  and the fuel tank  14 .  
         [0025]     The filler tube assembly  12  generally includes a funnel insert  30  and a filler tube  32  joined together at a joint  34 , which may be brazed, welded, adhered or otherwise mechanically or chemically joined. The two-piece assembly of the funnel insert  30  and the filler tube  32  provides a fueling path from a fuel supply source, such as a fuel nozzle  24 , located exterior the automobile body  22  to the fuel tank  14  within the automobile body  22 .  
         [0026]     The filler tube  32  is a one-piece seamless tube extending between the fuel tank  14  and the funnel insert  30  in order to communicate fuel flow from the funnel insert  30  to the fuel tank  14 . The filler tube  32 , at a first end  36 , is coupled to the fuel tank  14 . At a second end  38 , the filler tube  32  includes a funnel portion  40 , which is a flared portion of the filler tube  32  including the second end  38  and a transition portion  26 . The transition portion  26  provides a tapered configuration designed to cause fuel flowing therethrough to swirl. The funnel portion  40  of the second end  38  includes an axis offset axially from the axis of the first end  36  due to a generally elliptically shaped cross-section of the transition portion  26 .  
         [0027]     As shown in  FIGS. 1 and 2 , the funnel insert  30  is a one-piece seamless tube having a first diameter portion  42  at an inlet end  44 , a second diameter portion  46  at an insert end  48 , and an integrally formed nozzle retainer  60 . The first diameter portion  42  is larger than the second diameter portion  46  and is designed to receive the fuel cap  16 , which includes a sealing ring  17  and a stem  15  including threads  13 , and a conical portion  25  which joins the first and second diameter portions  42 ,  46 .  
         [0028]     The first diameter portion  42  of the funnel insert  30  includes a sealing surface  50  and threads  52 , both of which are integrally formed when manufacturing the funnel insert  30 . The sealing surface  50  will be a generally planar radial extension formed about a circumference of an inlet opening  54  formed in the inlet end  44  of the funnel insert  30 . With reference to  FIG. 3 , the sealing surface  50  provided about the inlet end  44  of the first diameter portion  42  of the funnel insert  30  provides a sealing surface against which the fuel cap  16  seals when threaded into threads  52 . The sealing ring  17  may be positioned between the fuel cap  16  and the sealing surface  50 .  
         [0029]     The threads  52 , which include thread segment  52   a  and thread segment  52   b , are formed in a sidewall  56  of the first diameter portion  42 . The threads  52  are inner diameter threads extending radially into the first diameter portion  42  and mate with the threads  15  formed radially inwardly in the stem  13 . Further, the threads  52  further function to hook or retain the fuel nozzle  24  during fueling through engagement with rings  80  of the fuel nozzle  24 , as shown in  FIG. 4 . Note that the threads  52  may be screw, quarter-turn, eighth-turn, or quick-turn thread configurations, as well as other known thread configurations.  
         [0030]     The nozzle retainer  60  is formed at the insert end  48  of the second diameter portion  46  and includes a nozzle opening  62  and vent holes  64 . Further, the nozzle opening  62  also axially offset in a radial direction opposite the transition portion  26  of the filler tube  32  in order to direct fuel supplied by the fuel nozzle  24 , which when inserted is disposed toward the transition portion  26 , whereby a swirl motion may be induced to the flowing fuel. The nozzle opening  62  further includes a cylindrical wall  63  surrounding the nozzle opening  62  and extending in the insert direction. The nozzle retainer  60  is positioned relative the threads  52  in order that the nozzle opening  62  is axially offset in a radial direction laterally aligned with one of the thread portions  52   a ,  52   b . As shown on  FIG. 4 , the threads  52  and nozzle opening  62 , through their relative positions and generally offset orientation relative the filler tube assembly  12 , retain the fuel nozzle  24  in a proper fuel-filling orientation.  
         [0031]     The funnel insert  30  and filler tube  32  are assembled and joined at the joint  34 , such as by a braze, weld, adhesive or other mechanical or chemical joint. The assembled filler tube assembly  12 , with the insert end  48  of the second diameter portion  46  inserted into the funnel portion  40  of the filler tube  32  creates a funnel member  70  having integrally formed therein the sealing surface  50 , the threads  52 , and the nozzle retainer  60 , as shown in  FIG. 5 . Overall, the configuration of the funnel member  70 , formed by the funnel insert  30  and the funnel portion  40  of the filler tube  32 , provides an arrangement that induces a swirling motion to the fuel as the fuel flows toward the filler tube  32  and fills the fuel tank  14  depending on the type of fuel nozzle used. The offset axial relationship of the inlet opening  54  and outlet opening  58  causes supplied fuel to impinge a sidewall  28  (coincident with the transition portion  26  of the filler tube  32 ) of the funnel member  70 , whereby fuel spirals as it flows through the filler tube  32 . The swirling motion of the fuel created by the funnel member  70  causes a suctioning effect or liquid seal that prevents fuel vapors from escaping into the atmosphere during refueling. The swirling motion of the fuel also creates a central void that allows any pressure buildup created during the fueling to vent, thereby preventing premature shutoff of the fuel nozzle  24 .  
         [0032]     The funnel member  70  includes a relatively larger diameter section  72  forming the inlet opening  54 , which is arranged about an axis  74  and spaced-apart axially offset from a relatively smaller diameter tubular section  76  arranged about an axis  78  forming the outlet opening  58 . As shown, axes  74  and  78  are parallel, but can be positioned divergently.  
         [0033]     The larger diameter section  54  and the smaller diameter section  58  are connected to one another by the transition portion  26 , which generally tapers from the larger diameter section  54  to the smaller diameter section  58 . The transition portion  26  intersects larger diameter section  72  at an elliptically-shaped junction that lies in a plane inclined at angle A, which is 60°-85° from the axes  74 ,  78 . By way of an example, the inlet opening  54  may have a diameter D 1  of approximately 60 millimeters and the tubular section might have a diameter D 2  of approximately 25 millimeters with a coaxial offset at a distance X of approximately 15 millimeters. The relationship of the inlet opening  54  and the outlet opening  58  and the configuration of the transition portion  26  causes the fuel to swirl during fueling.  
         [0034]     The fuel filler tube assembly  12  may be made by a number of forming processes including eyelet/progressive stamping, eyelet stamping, progressive die stamping, transfer die stamping, and hydroforming. If the fuel tank filler neck is made of plastics, injection molding and compression molding are suitable methods for manufacturing the fuel filler tube assembly  12 .  
         [0035]     The fuel filler tube assembly  12  is manufactured by forming the funnel insert  30  and expanding the second end  38  of the filler tube  32  to create the funnel member  40 . The insert end  48  of the funnel insert  32  is positioned within the second end  38  of the filler tube  32  in fluid communication with the funnel member  40 . The joint  34  between the filler tube  32  and funnel insert  30  is formed to mechanically or chemically secure to one another. The assembled fuel filler tube assembly  12  is connected to the fuel tank  14  and the automobile body  22 .  
         [0036]     The funnel insert  30  is formed by stamping a one-piece seamless tube having the larger first diameter portion  42  defining the inlet end  44  and the smaller second diameter portion  46  defining the insert end  48  including the integrally formed nozzle retainer  60 . The stamping method may be progressive stamping, wherein sheet stock is formed into a circular blank that is drawn into a cup shape. This drawing method may include several dies in which the funnel insert is progressively formed or deep drawn to shape the first diameter portion  42 , the second diameter portion  46 , and the transition portion  26  therebetween. The inlet opening  54  of the funnel insert  30  is defined by rolling over an edge of the inlet end  44  to define the sealing surface  50  about the inlet opening  54 . The nozzle retainer  60  is defined by piercing the nozzle opening  62  and the vent holes  64  in a bottom surface or insert end  48  of the drawn cup shape.  
         [0037]     The filler tube  32  is formed by cutting tube stock to a desired length. The end of the tube stock to receive the funnel insert  30  is flared to create the funnel portion  40  by expanding the diameter of the tube through an end-forming process. For example, a first punch having a first diameter is forced into the second end  38  of the filler tube  32 . Because the diameter of the first punch is larger than the diameter of the second end  38 , the insertion of the punch expands the diameter of the second end  38 . If necessary, this process is repeated with a second punch having a diameter larger than the first punch to expand the second end  38  farther. This process may be repeated as necessary to expand the diameter of the second end  38  of the filler tube  24  to the desired diameter without severely stressing or weakening the tube. The filler tube  32  is also bent to accommodate the geometry of a particular automotive vehicle application.  
         [0038]     With reference to  FIG. 7 , the threads  52  may be formed in the funnel insert  30  by a forming tool  90  including wheels  92 ,  94 , which in combination are of appropriate shape to form the threads  52  in the sidewall of the funnel insert  30 . The wheels  92 ,  94 , which are mounted on shafts  96 ,  98 , spin in directions A, B as they press on the sidewall  38  to form the threads  36 . This spinning allows forming tool  90  to form the periphery of the funnel insert  30  about the inlet opening  54 .  
         [0039]     With reference to  FIG. 8 , another method of forming threads  52  in the funnel insert  30  is provided. The threads  52  are made by a crimping tool  100 , which includes crimping halves  102 ,  104 . The sidewall is placed between crimping halves  102 ,  104 , which are pressed together in directions A, B to form the threads  52 . This process is repeated along the sidewall  38  until the threads  52  are completely formed in the funnel insert  30  about the inlet opening  54 .  
         [0040]     The funnel insert  30  and filler tube  32  are aligned and joined by the joint  34 , which may be a weld, braze, adhesive, or some other mechanical or chemical joint. The integrity of the funnel insert  30 , filler tube  32  and the joint  34  may be leak tested to verify the integrity of the components and their interconnection.  
         [0041]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.