Abstract:
A fuel port elbow composed of a plastic port body overmolding an electrically conductive, truncated insert tube such that there is no external dissimilar materials boundary. The tube has a tube first segment, a tube elbow segment and a tube second segment truncated such that the dissimilar materials boundary at the tube truncation is internal to the port body. A port body is integral with the plastic of a flange cover, and overmolds part of the tube first segment and all of the tube elbow and second segments. The port body has a port body second segment having a port body passage communicating with the tube passage and extending remotely from the tube truncation, being adapted for connecting with a fuel line.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present patent application claims the benefit of provisional patent application Ser. No. 61/036,536, filed on Mar. 14, 2008, which application is presently pending. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to fuel pump modules which are interfaced with fuel tanks for motor vehicles, and more particularly to a fuel port of the cover flange thereof. Still more particularly, the present invention relates to a fuel port elbow having an overmolded, electrically conductive, truncated insert tube. 
       BACKGROUND OF THE INVENTION 
       [0003]    Motor vehicle fuel tanks provide not only a reservoir for fuel but also must have accommodation for adding fuel, delivering fuel (i.e., to the engine) and monitoring the amount of the fuel therein. It has become a common practice to combine the fuel delivery and monitoring functions via a fuel pump module which is removably interfaced with an opening of the fuel tank sidewall. 
         [0004]      FIG. 1  depicts an example of a motor vehicle fuel tank  10  having, by way of example, a saddle shape featuring two fuel sumps  10   a ,  10   b . The fuel tank sidewall  12  is provided with first and second openings  12   a ,  12   b , each opening being disposed over a respective fuel sump  10   a ,  10   b . At the first sump  10   a , and interfaced sealingly with the first opening  12   a , is a fuel pump module  14 , and at the second sump  10   b  and interfaced sealingly with the second opening  12   b  is a secondary fuel transfer source  16  which is fluidically connected to the fuel pump module  14  via a transfer line  18 . 
         [0005]    The fuel pump module may be a part of a return fuel system or of a returnless fuel system. With respect to a return fuel system, now used mostly in diesel fuel applications, there are feed and return fuel lines, wherein fuel is constantly pumped, and what is not used by the engine is returned to the fuel tank. In a returnless fuel system, which is used most commonly today, fuel is supplied on demand to the engine, there being no return fuel line, only a feed fuel line connected with the fuel pump module. Returnless fuel systems may be of a mechanical type, commonly referred to as “MRFS” or of an electronic type, commonly referred to as “ERFS”, depending on the control modality of the fuel system. 
         [0006]      FIG. 2  depicts a schematic representation of the functional aspects of a fuel pump module  20  utilized in the prior art, as for example in the manner of fuel pump module  14  in  FIG. 1  with respect to a fuel tank of a returnless fuel system. A module reservoir  22  is defined by a plastic module sidewall  20   a . A fuel pump  24  draws fuel through a fuel strainer  26  in the module reservoir. The pumped fuel F is then sent via a connector conduit  28  to a fuel filter  30 , whereupon after filtering, the fuel passes through a filter conduit  32  to a fuel port elbow  34  from which the fuel is delivered to the engine via a feed fuel line  35 . By way of comparison, in a return fuel system the fuel is continuously pumped, and any amount not utilized by the engine is returned to the fuel pump module  20  by a return fuel line (not shown), and for this purpose a second fuel port elbow would be provided which is connected with the fuel return line, the return fuel being dumped into the module reservoir. The fuel port elbow  34  (and, if present, also the second fuel port elbow) is sealingly connected with a cover flange  36  which is, in turn, sealingly seated at the first opening  12   a  and removably affixed thereto by a locking ring  40  (see  FIG. 1 ). A fuel level sensor  42  is connected with the module sidewall  20   a , which may be, for example, of the pivoting float type. A pressure relief valve  44  is located at the fuel filter  30 . Guide rods  46 , having guide springs, guidably interconnect the cover flange  36  with the module sidewall  20   a . 
         [0007]    In order to supply electricity to operate the fuel pump  24  and the fuel level sensor  42 , electrical leads  38  are provided: power and ground leads  38   a ,  38   b  for the fuel pump and voltage in and out leads  38   c ,  38   d  for the fuel level sensor. In view of the electrical interconnections, it is desirable for the fuel pump  24 , the connector conduit  28 , the fuel filter  30  and the filter conduit  32  to be electrically conductive and be connected, along with the fuel level sensor  42 , via for example a grounding lead  38   e , to the ground lead  38   b  (in applications where the fuel pump is absent, grounding is via a ground lead with the fuel level sensor). The guide rods  46  are metallic and also connected to ground. 
         [0008]    It is known that conduit surfaces which are exposed to turbulent fuel flow may, under some circumstances, acquire an electrostatic (or static electric) charge. It is further known that electrostatic charge can be removed by electrically connecting a charged object to an electrical ground. In this regard, SAE International report entitled “Surface Vehicle Recommended Practice” regarding “Fuel Systems and Components—Electrostatic Charge Mitigation”, report number SAE J1645 issued February 1994 and revised August 2006, which report is hereby herein incorporated by reference, sets forth a standard for the insulative portions of a fuel system which do not need to be conductive and grounded (see Section A.4 and subsections thereof), provided the fuel flow path is short or if multiple ground paths are provided, wherein “short” is considered to be (see subsection A.4.2) as less than about one-tenth of the product of the highest mean fuel flow velocity times the dielectric relaxation time of the fuel. Irrespective of the foregoing, in the portions of conduits where relatively low fuel flow rates are present, conductive and grounded portions may not be needed as a countermeasure for electrostatic charge accumulation. 
         [0009]    Because fuel flowing through the fuel port elbow experiences a 90 degree change in direction, it is possible for fuel flow turbulence to develop thereat. Whether or not that can result in electrostatic charge accumulation, it is the practice in the art to have the fuel port elbow include a conductive material, such as an electrically conductive tube  48  as shown at  FIG. 3A , which is electrically connected to the electrical ground lead, via, for example, the electrical connections as between the filter conduit  32 , the fuel filter  30 , the connector conduit  28  and the grounded fuel pump  24 . 
         [0010]    The prior art fuel port elbow  34  of  FIG. 2  is shown in detail at  FIG. 3A . The fuel port elbow  34  includes a conductive plastic (i.e., a plastic with for example graphite or metallic particle fill) tube  48 , having a first tube component  48   a , a second tube component  48   b , and an elbow tube component  48   c  joining the first and second tube components at right angle to each other, wherein the first tube component has a nipple  48   d  for connecting to the filter conduit and the second tube component has a nipple  48   e  for connecting to the fuel line. 
         [0011]    The tube  48  provides a suitable electrical conductivity, but the first tube component  48   a  is partly above and partly below the cover flange  36 , wherein the conductive plastic thereof must be sealed in relation to the non-conductive plastic of the cover flange  36 . The prior art sealing solution is to provide a plastic cap flange upper overmold  50  which is inclusive of the elbow tube component  48   c , and a plastic cap flange lower overmold  52 , wherein the cap flange upper overmold and the cap flange lower overmold are integral with the plastic of the cap flange  36 , and each terminate at a respective upper and lower annulus  54 ,  56  of the tube  48 . 
         [0012]    Referring next to  FIGS. 3B through 3D  other prior art fuel port elbows known in the prior art will be briefly discussed. 
         [0013]    At  FIG. 3B , a prior art fuel port elbow  60  is depicted in which a metallic tube  62  has a first tube component  62   a , a second tube component  62   b , and an elbow tube component  62   c  joining the first and second tube components, with nipples  62   d ,  62   e  as generally recounted for the purposes with respect to  FIG. 3A . A cap flange upper overmold  66   a  extends above the upper side  64   a  of the cap flange  64 , and a cap flange lower overmold  66   b  extends below the cap flange underside  64   b,  both overmolds being integral with the plastic of the cap flange  64 . 
         [0014]    At  FIG. 3C , a prior art fuel port elbow  70  is depicted in which a metallic tube  72  has a first tube component  72   a , a second tube component  72   b , and an elbow tube component  72   c  joining the first and second tube components, with similar attributes to the fuel port elbow  60  of  FIG. 3B . Now, the cap flange  74  is metallic and sealingly conjoined by welding or brazing  76  between the tube  72  and a collar  78  of the cap flange  74 . 
         [0015]    At  FIG. 3D , a prior art fuel port elbow  80  is depicted in which an electrically conductive plastic tube  82  has a first tube component  82   a , a second tube component  82   b , and an elbow tube component  82   c  joining the first and second tube components, wherein the first tube component has a nipple  82   d  for connecting to the fuel filter and the second tube component has a nipple  82   e  for connecting the fuel line. The cap flange  84  is also composed of the conductive plastic material and integral with the electrically conductive plastic tube. The electrically conductive plastic is, for example, plastic with a metal particle or graphite fill. 
         [0016]    While the prior art fuel port elbow  34  works well for fuel feed in a returnless fuel system and for both fuel feed and fuel return in a return fuel system, an external boundary  58  exists at the upper annulus, where the dissimilar plastic materials conjoin with each other, whereat problems could arise related to exposure to the elements of weather external to the fuel tank or fuel vapor permeation to the atmosphere, which problems could be exacerbated by manufacturing tolerances. The other types of prior art fuel port elbows have drawbacks as well. For example, the partly overmolded metal tube fuel port elbow  60  has an exterior dissimilar materials boundary  68 ; the metal only fuel port elbow  70  requires the cap flange be made out of metal instead of plastic, which is more expensive; and, finally, the all plastic fuel port elbow  80  requires the cap flange and the fuel port elbow to be constructed of relatively expensive electrically conductive plastic. 
         [0017]    Accordingly, it would be desirable if somehow the conductivity at the fuel port elbow could be provided, while at the same time eliminating all the drawbacks of the prior art. 
       SUMMARY OF THE INVENTION 
       [0018]    The present invention is a fuel port elbow composed of a plastic port body overmolding an electrically conductive, truncated insert tube such that there is no external dissimilar materials boundary. 
         [0019]    The fuel port elbow according to the present invention includes an electrically conductive, truncated insert tube having a tube passage. The truncated insert tube includes an insert tube first segment which passes through a cover flange for the fuel tank; an insert tube second segment which is oriented generally perpendicular to the insert tube first segment; and an insert tube elbow segment which joins the insert tube first and second segments. The insert tube second segment is truncated. 
         [0020]    The fuel port elbow according to the present invention further includes a plastic port body sealingly connected with the plastic of the cover flange, wherein the port body includes a port body first segment which is sealingly connected to the cover flange, preferably by being integrally formed therewith; a port body second segment which is generally perpendicular in relation to the port body first segment and carries a port body passage; and a port body elbow segment which joins the port body first and second segments. 
         [0021]    Above the flange cover (i.e., exterior to the fuel pump module) the insert tube first segment, the insert tube elbow segment and the insert tube second segment are overmolded by the port body, whereby the tube passage aligns and communicates with the port body passage, and the dissimilar materials boundary as between the plastic of the port body and the electrically conductive material of the insert tube is internal to the port body. Below the flange cover (i.e., interior to a fuel pump module), the insert tube first segment is overmolded by a lower overmold to an annulus of the insert tube first segment. 
         [0022]    The length of the insert tube second segment, that is, the location of the tube truncation, is predetermined by the location at which fuel flow has exited the highly turbulent turn of the insert tube elbow segment and has now become less turbulent. More particularly, per SAE J1645, Section A.4 thereof, the truncation is disposed such that the adjoining port body passage immediately downstream of the truncation is short (as defined in SAE J1645), straight and has two adjacent internal ground paths (one ground path being the insert tube at one end of the port body passage and a conductive fuel line at the other end of the port body passage), such that the port body second segment (which provides the port body passage) may be insulative. 
         [0023]    Advantageously, the fuel port elbow according to the present invention provides an electrically conductive surface at the interior of the elbow portion thereof where turbulent fuel flow may arise, minimizes insert tube material cost, and eliminates an external dissimilar materials boundary. 
         [0024]    Accordingly, it is an object of the present invention to provide a fuel port elbow composed of a plastic port body overmolding an electrically conductive insert tube such that there is no external dissimilar materials boundary. 
         [0025]    This and additional objects, features and advantages of the present invention will become clearer from the following specification of a preferred embodiment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a perspective view of a fuel tank, showing in particular a fuel pump module interfaced therewith. 
           [0027]      FIG. 2  is a schematic representation of a prior art fuel pump module for a fuel tank, wherein the fuel port elbow thereof is known in the prior art. 
           [0028]      FIG. 3A  is a broken-away, sectional side view of a cover flange for a fuel pump module, wherein, per the prior art, the fuel port elbow thereof is characterized by a conductive plastic insert tube being partially overmolded, as depicted at  FIG. 2 . 
           [0029]      FIG. 3B  is a broken-away sectional side view of a cover flange for a fuel pump module, wherein, per the prior art, the fuel port elbow thereof is characterized by a metallic insert tube being partly overmolded. 
           [0030]      FIG. 3C  is a broken-away sectional side view of a cover flange for a fuel pump module, wherein, per the prior art, the fuel port elbow thereof and the cover flange are both metallic. 
           [0031]      FIG. 3D  is a broken-away sectional side view of a cover flange for a fuel pump module, wherein, per the prior art, the fuel port elbow thereof and the cover flange are both composed of an electrically conductive plastic. 
           [0032]      FIG. 4  is a schematic representation of a fuel pump module for a fuel tank for a returnless fuel system, wherein the fuel port elbow thereof is according to the present invention. 
           [0033]      FIG. 5  is a broken-away, sectional side view of a cover flange for a fuel pump module, wherein, according to the present invention, the fuel port elbow thereof is characterized by an overmolded electrically conductive insert tube that is truncated such that the dissimilar materials boundary is internalized to the overmold, as depicted at  FIG. 4 . 
           [0034]      FIG. 6  is a partly sectional, perspective view of a fuel pump module including a pair of fuel port elbows according to the present invention for use in a return fuel system. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0035]    Referring now to the Drawing,  FIGS. 4 through 6  depict various aspects of a fuel port elbow  100  which is sealingly connected to a cover flange of a fuel pump module of a fuel tank (as for example see  10  at  FIG. 1 ). 
         [0036]      FIG. 4  depicts a schematic representation of the functional aspects of a fuel pump module  104  similar to that discussed above at  FIG. 2  with respect to a fuel tank of a returnless fuel system, wherein the primary difference of  FIG. 4  with respect to  FIG. 2  is the fuel port elbow  100  according to the present invention, and wherein the description shall utilize similar numerals to describe similar components. 
         [0037]    A module reservoir  22  is defined by a plastic module sidewall  20   a . A fuel pump  24  draws fuel through a fuel strainer  26  in the module reservoir. The pumped fuel F is then sent via a connector conduit  28  to a fuel filter  30 , whereupon after filtering, the fuel passes through a filter conduit  32  to a fuel port elbow  34  from which the fuel is delivered to the engine via a feed fuel line  122 , which is electrically conductive and grounded. By way of comparison, in a return fuel system the fuel is continuously pumped, and any amount not utilized by the engine is returned to the fuel pump module  20  by a return fuel line (see  FIG. 6 ), and for this purpose a second fuel port elbow would be provided which is connected with the fuel return line, the return fuel being dumped into the module reservoir. The fuel port elbow  34  (and, if present, also the second fuel port elbow) is sealingly connected with a cover flange  102  which is, in turn, sealingly seated at the first opening  12   a  and removably affixed thereto by a locking ring  40  (see  FIG. 1 ). A fuel level sensor  42  is connected with the module sidewall  20   a , which may be, for example, of the pivoting float type. A pressure relief valve  44  is located at the fuel filter  30 . Guide rods  46 , having guide springs, guidably interconnect the cover flange  36  with the module sidewall  20   a.    
         [0038]    In order to supply electricity to operate the fuel pump  24  and the fuel level sensor  42 , electrical leads  38  are provided: power and ground leads  38   a ,  38   b  for the fuel pump and voltage in and out leads  38   c ,  38   d  for the fuel level sensor. In view of the electrical interconnections, the fuel pump  24 , the connector conduit  28 , the fuel filter  30  and the filter conduit  32  are electrically conductive and connected, along with the fuel level sensor  42 , via for example a grounding lead  38   e , to the ground lead  38   b  (in applications where the fuel pump is absent, grounding is via a ground lead with the fuel level sensor). The guide rods  46  are metallic and also connected to ground. 
         [0039]    The fuel port elbow  100  includes an electrically conductive insert tube  120  which is electrically connected to the electrical ground lead, via, for example, the electrical connections as between the filter conduit  32 , the fuel filter  30  the connector conduit  28  and the grounded fuel pump  24 . 
         [0040]    As shown at  FIG. 5 , the fuel port elbow  100  according to the present invention includes a plastic port body  110  sealingly connected with the upper side  102   a  (i.e., exterior to the fuel pump module) of the cover flange  102 . The port body  110  includes a port body first segment  110   a  which is sealingly connected to, preferably by being integrally formed with, the plastic of the cover flange  102 . The port body  110  also includes a port body second segment  110   b  which is generally perpendicular to the port body first segment, has a port body passage  124 , and is adapted for connecting to the electrically conductive fuel line (see  122  of  FIG. 4 ), as for example via a nipple  110   d . The port body  110  further includes a port body elbow segment  110   c , wherein the port body elbow segment joins the port body first and second segments  110   a ,  110   b.    
         [0041]    As additionally shown at  FIG. 5 , the fuel port elbow  100  further includes an electrically conductive, truncated insert tube  120 , defining a tube passage  130 . The truncated insert tube  120  is preferably composed of a conductive plastic, as for example a plastic with a conductive material fill, as for example metal particles or graphite, or composed of another conductive material. The truncated insert tube  120  includes an insert tube first segment  120   a  which passes through the cover flange  102 ; an insert tube second segment  120   b  which is oriented generally perpendicular to the insert tube first segment; and an insert tube elbow segment  120   c  joining the insert tube first and second segments. The insert tube second segment  120   b  is truncated  120   b ′, the location being for example generally adjacent the insert tube elbow segment  120   c . The portion  120   a ′ of the insert tube first segment  120   a  which is intended to be located within the fuel pump module carries an annulus  128 , and between the annulus and a terminal end  134  is adapted to connect to the electrically conductive filter conduit (see  32  of  FIG. 4 ), as for example via a nipple  120   a″.    
         [0042]    The length of the insert tube second segment  120   b , that is, the location of the tube truncation  120   b ′, is predetermined by the location at which fuel flow has exited the highly turbulent turn of the insert tube elbow segment  120   c  and has now become less turbulent. More particularly, per SAE J1645, Section A.4 thereof, the truncation is disposed such that the adjoining port body passage  124  immediately downstream of the truncation is short (as defined in SAE J1645), straight and has two adjacent internal ground paths, wherein one ground path is the insert tube  120  at the end of the port body passage (where the truncation is disposed and whereat a dissimilar materials boundary  132  exists), and the other ground path is the conductive fuel line  122  (see  FIG. 4 ) disposed at the other end of the port body passage (i.e., where the distal end  110   e  of the insert tube second segment is located), such that the port body second segment (which provides the port body passage) may be insulative. 
         [0043]    According to a methodology of making, the truncated insert tube is placed into a plastic injection tool, and plastic is injected to form the cap flange and the port body, and, at the underside  102   b  of the flange cover (i.e., interior to the fuel pump module), the insert tube first segment  120   a  is overmolded by a lower overmold  126  to the annulus  128  of the insert tube first segment. At the upperside  102   a  of the flange cover (i.e., exterior to the fuel pump module), the insert tube first segment, the insert tube elbow segment  120   c , and the insert tube second segment  120   c  are overmolded by the port body, whereby the truncation  120   b ′ of the insert tube second segment  120   b  flushly abuts  110   b ′ the port body second segment  110   b  such that the tube passage  130  is smoothly aligned and communicates with the port body passage  124 . The port body second segment  110   b  overmolding of the insert tube second segment  120   b  is such that a distal end  110   e  of the port body second segment is disposed in spaced relation with respect to said tube second segment, whereby the dissimilar materials boundary  132  as between the plastic of the port body and the conductive plastic of the truncated insert tube is internal to the port body. 
         [0044]    Turning attention now to  FIG. 6 , a fuel pump module  140  for a return fuel system is depicted. A feed fuel conduit  142  and a return fuel conduit  144  are each equipped with a respective fuel port elbow  100  according to the present invention, which is, in turn, respectively connected to a feed fuel line  146  and a return fuel line  148 . 
         [0045]    To those skilled in the art to which this invention appertains, the above described preferred embodiment may be subject to change or modification. Such change or modification can be carried out without departing from the scope of the invention, which is intended to be limited only by the scope of the appended claims.