Abstract:
A dual fuel pump fuel extraction system for saddle fuel tanks. A primary modular reservoir assembly (MRA) includes an electric primary fuel pump located in the primary sump of a saddle fuel tank and a secondary MRA including an electric secondary fuel pump located in the secondary sump of the saddle fuel tank, wherein both the primary and secondary fuel pumps extract fuel from the primary sump and simultaneously transfer fuel between the primary and secondary sumps so as to thereby ensure both the primary and secondary fuel pumps have fuel, without starving one before the other, until fuel becomes depleted from the saddle fuel tank.

Description:
TECHNICAL FIELD 
     The present invention relates to automotive fuel tanks, and more particularly to saddle fuel tanks. Still more particularly, the present invention relates to improved fuel pump configurations for saddle fuel tanks. 
     BACKGROUND OF THE INVENTION 
     Automotive saddle fuel tanks have a tank shell configured with a centrally disposed bight in the bottom thereof. The bight provides an exterior concavity which is intended to provide accommodation for drivetrain and/or exhaust components of the motor vehicle to pass freely therethrough. While providing free space at the exterior of the tank shell, the bight also provides a riser within the fuel tank which effectively creates two sumps on either side thereof, wherein the two sumps conjoin in the space of the fuel tank higher than the height of the riser. In view of the presence of the bight, wherein the riser creates two separated sumps, attention must be carefully given to the fuel extraction system. 
       FIG. 1A  is a sectional schematic view of a conventional saddle fuel tank  10 . The tank shell  12  defines a bottom  14  and an oppositely disposed top  16 , wherein a bight  15  provides a concavity  18  exterior to the fuel tank and a riser  20  interior to the fuel tank, in turn providing a primary sump  22  and a secondary sump  24 . 
     The saddle fuel tank  10  has a fuel extraction system in the form of a single modular reservoir assembly (MRA)  25 . The top  16  of the tank shell  12  carries primary and secondary modular reservoir assembly (MRA) covers  26 ,  28 , wherein the primary MRA cover is a part of the single MRA  25 . An inlet check valve  30  provides an entry for fuel into the fuel tank  10 , wherein the primary sump  22  is identified as the sump first filled by fuel introduced from the inlet check valve. An in-tank disposed electric fuel pump  32 , when energized, pumps fuel from the primary sump  22 , through a strainer  35 , and, via a feed line  34 , out of the fuel tank through the primary MRA cover  26 , and, via a feed line  36  to a fuel filter  38  situated in a filter assembly  40 , whereby the fuel is then filtered by the fuel filter  38 . 
     Fuel which is not used by the engine is returned, via a return port  42  on the fuel line  44  upstream of the filter  38 , to the fuel tank  10  through the primary MRA cover  26  and, in turn, through a return line  46 , to an in-tank pressure regulator  48 . The in-tank pressure regulator  48  maintains a set pressure of the fuel in the fuel line  44  upstream of the return port  42 , and bypasses fuel via a return line  50  to a scavenge jet pump  52 . The scavenge jet pump  52  scavenges bulk fuel  54  into a primary sump reservoir bucket  56 , wherein the bucket is connected to the primary MRA cover  26  by rods (not shown). Additionally, feed fuel from the electric pump  32  is bled off via a bleed line  58  to run a transfer jet pump  60 . The transfer jet pump  60  draws fuel from the secondary sump  24  via a transfer line  62  into the primary sump reservoir bucket  56 . 
     The aforedescribed saddle fuel tank fuel system is limited by the fact that only one pump can be placed at the primary sump, since the primary and secondary MRA covers are only 4.5 inches in diameter. 
     What remains needed in the art is a dual electric pump saddle tank fuel extraction system which avails itself of both the primary and secondary sumps for fuel extraction system packaging, wherein fuel is continually available to both electric pumps without starving one before the other when fuel becomes depleted. 
     SUMMARY OF THE INVENTION 
     The present invention is a generally symmetrically configured, dual electric fuel pump saddle tank fuel extraction system which avails itself of both the primary and secondary sumps of the saddle fuel tank for fuel extraction system packaging, wherein fuel is continually available to both electric fuel pumps without starving one before the other when fuel in the tank becomes completely depleted. 
     The dual fuel pump fuel extraction system according to the present invention is composed of a primary modular reservoir assembly (MRA) including an electric primary fuel pump located in the primary sump of a saddle fuel tank and a secondary MRA including an electric secondary fuel pump located in the secondary sump of the saddle fuel tank, wherein both the primary and secondary fuel pumps extract fuel from the primary sump and simultaneously transfer fuel between the primary and secondary sumps so as to thereby ensure both the primary and secondary fuel pumps have fuel, without starving one before the other, until fuel becomes depleted from the saddle fuel tank. 
     The primary fuel pump extracts fuel from the primary sump and transfers the fuel exterior to the saddle fuel tank via a primary MRA cover, and the secondary fuel pump extracts fuel from the primary sump and transfers the fuel exterior to the saddle fuel tank via the secondary MRA cover. Thereafter, the fuel from the primary and secondary fuel pumps is delivered to a filter assembly. Any excess fuel (fuel not presently needed by the engine) is then returned from the filter assembly to the saddle fuel tank via return lines passing respectively through each of the primary and secondary MRA covers. A pressure regulator may be located at the filter assembly or a pair of pressure regulators may be provided in the saddle fuel tank at the return lines downstream of the primary and secondary MRA covers. Preferably, fuel transfer between the primary and secondary fuel pumps is, in part, provided by a plurality of jet pumps located in the primary and secondary MRAs. 
     Accordingly, it is an object of the present invention to provide a fuel extraction system for a saddle fuel tank, wherein an electric fuel pump is located in each of the sumps, respectively, wherein fuel is extracted from the primary sump, and wherein fuel is internally transferred between the sumps so that the pumps can only run dry simultaneously. 
     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 
       The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views. 
         FIG. 1A  is a schematic view of a saddle fuel tank equipped with a prior art fuel extraction system. 
         FIG. 1B  is a schematic view of a filter assembly know in the prior art for connection to the prior art fuel extraction system of  FIG. 1A . 
         FIG. 2  is a schematic view of a saddle fuel tank equipped with a first preferred embodiment of the dual fuel pump fuel extraction system according to the present invention, wherein a return tee is a component of a secondary fuel module. 
         FIG. 3  is a schematic view of a saddle fuel tank equipped with a second preferred embodiment of the dual fuel pump fuel extraction system according to the present invention, which is similar to that of  FIG. 2 , wherein now an auxiliary fuel pump is included in the primary sump. 
         FIG. 4  is a schematic view of a saddle fuel tank equipped with a third preferred embodiment of the dual fuel pump fuel extraction system according to the present invention, which is similar to  FIG. 2 , wherein now the return tee is absent. 
         FIG. 5  is a schematic view of a saddle fuel tank equipped with a third preferred embodiment of a dual fuel pump fuel extraction system according to the present invention, which is similar to  FIG. 4  wherein now a pair of pressure regulators are provided. 
         FIG. 6  is a schematic view of a first embodiment of a fuel delivery system for use with the first, second and third preferred embodiments of the dual fuel pump fuel extraction system according to the present invention. 
         FIG. 7  is a schematic view of a second embodiment of the fuel delivery system for use with the first, second and third preferred embodiments of the dual fuel pump fuel extraction system according to the present invention. 
         FIG. 8  is a schematic view of a third embodiment of the fuel delivery system for use with the fourth preferred embodiment of the dual fuel pump fuel extraction system according to the present invention. 
         FIG. 9  is a schematic view of a fourth embodiment of the fuel delivery system for use with the fourth preferred embodiment of the dual fuel pump fuel extraction system according to the present invention. 
         FIG. 10  is a schematic view of a saddle fuel tank equipped with a modification of the first preferred embodiment of the dual fuel pump fuel extraction system of  FIG. 2 . 
         FIG. 11  is a schematic view of a modification of the first embodiment of a fuel delivery system of  FIG. 6  for use with the modified embodiment of the dual fuel pump fuel extraction system of  FIG. 10 . 
         FIGS. 12 and 13  are schematic views of a saddle fuel tank equipped with further modifications of the first preferred embodiment of the dual fuel pump fuel extraction system of  FIG. 2 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the Drawing,  FIGS. 2 through 5  depict several preferred embodiments of the dual fuel pump fuel extraction system  100 – 400  according to the present invention,  FIGS. 6 through 9  depict several embodiments of a fuel delivery systems  500 – 800  according to the present invention for selected use with the aforesaid preferred embodiments of the dual fuel pump fuel extraction system, and  FIGS. 10 through 13  depict exemplar modifications of selected embodiments  100 ,  500 . 
     Each of  FIGS. 2 through 5  depict a sectional schematic view of a saddle fuel tank  80  having a tank shell  82  defining a bottom  84  and an oppositely disposed top  86 , wherein a bight  88  at the bottom provides a concavity  90  exterior to the fuel tank and a riser  92  interior to the fuel tank, in turn providing a primary sump  94  and a secondary sump  96 , wherein inlet check valve  98  through the tank shell provides an entry for fuel into the saddle fuel tank above the primary sump  94 . 
     Turning attention now to  FIG. 2 , the first embodiment of the dual fuel pump fuel extraction system  100  will be detailed. 
     The saddle fuel tank  80  has a dual fuel pump fuel extraction system  100  in the form of dual modular reservoir assemblies (MRAs), wherein a primary MRA  102  is generally situated in the primary sump  94  and includes a primary MRA cover  104  formed in the top  86  of the tank shell  82 , and a secondary MRA  106  which is generally situated in the secondary sump  96  and includes a secondary MRA cover  108  formed in the top of the tank shell, wherein the primary and secondary MRA covers contain feed and return ports and may utilize quick connects. 
     The primary MRA  102  includes an electric primary fuel pump  110  which draws fuel from a primary bucket  112  via a strainer  114 , all of which are located in the primary sump  94 . The primary bucket  112  and the primary MRA cover  104  are connected together, as for example by rods (not shown). Fuel is pumped under pressure by the primary fuel pump  110  to a primary feed port  104   a  of the primary MRA cover  104  via a primary feed line  116 . 
     The secondary MRA  106  includes an electric secondary fuel pump  118  situated in the secondary sump  96  which draws fuel, in response to suction of the secondary fuel pump, from the primary bucket  112  via a strainer  120  and a pump transfer line  122  which transfers fuel from the primary bucket to a secondary bucket  124  in the secondary sump, in which the secondary fuel pump is located. In this regard, the pump transfer line  122  is able to draw fuel out of the primary side of the fuel tank because it is plumbed into the inlet side of the secondary fuel pump  118 . The pump transfer line  122  includes a return tee  126 . The secondary bucket  124  and the secondary MRA cover  108  are connected together, as for example by rods (not shown). Fuel is pumped under pressure by the secondary fuel pump  118  to a secondary feed port  108   a  of the secondary MRA cover  108  via a secondary feed line  128 . 
     It is seen from the foregoing that fuel is pumped by the primary and secondary fuel pumps  110 ,  118  at a flow rate generally doubling the flow rate would be available to the engine if having only one MRA were used (as in the prior art). This feature is further enhanced in that both the primary and secondary fuel pumps are assured having fuel available to pump at all times up until the saddle fuel tank  80  runs dry of fuel, as will be further detailed hereinbelow. 
     Fuel is actively transferred from the secondary sump  96  to the primary sump  94  via a first primary jet pump  130 , a first sump transfer line  132  which may or may not originate in the secondary bucket  124 , and a first sump transfer line extension  132   a . The first primary jet pump  130  is run by pressurized fuel in the primary feed line  116  via a first primary feed tap line  134 . The first sump transfer line is connected to the inlet of the first primary jet pump and withdraws fuel from the secondary sump  96 , while the first sump transfer line extension  132   a  is connected to at the outlet of the first primary jet pump  130  and delivers fuel to the primary bucket  112 . 
     Fuel is also actively transferred from the secondary sump  96  to the primary sump  94  via a first secondary jet pump  136 , a second sump transfer line  138  and a second sump transfer line extension  138   a  which may or may not originate in the secondary bucket  124 . The first secondary jet pump  136  is run by pressurized fuel in the secondary feed line  128  via a first secondary feed tap line  140 . The second sump transfer line extension  138   a  connects to the inlet of the first secondary jet pump  130  and withdraws fuel from the secondary sump  96 , while the second sump transfer line  138  connects to the outlet of the first secondary jet pump and delivers fuel to the primary bucket  112 . 
     In addition, fuel is actively transferred into the primary bucket  112  from the primary sump  94  via a second primary jet pump  144 . The second primary jet pump  144  is run by pressurized fuel in the primary feed line  116  via a second primary feed tap line  148 . Bulk fuel  150  in the primary sump is drawn into the primary bucket  112  by operation of the second primary jet pump  144 , and is discharged into the primary bucket for immediate availability to the primary fuel pump  110 . 
     In addition further, fuel is actively transferred into the secondary bucket  124  from the secondary sump  96  via a second secondary jet pump  152 . The second secondary jet pump  152  is run by pressurized fuel in the secondary feed line  128  via a second secondary feed tap line  154 . Bulk fuel  156  in the secondary sump is drawn into the secondary bucket  124  by operation of the second secondary jet pump  152 , and is discharged into the primary bucket for immediate availability to the secondary fuel pump  118 . 
     The primary feed line  116  transfers fuel under pressure from the primary fuel pump  110  to the primary feed port  104   a  of the primary MRA cover  104 . A primary external feed line  160  is connected to the primary feed port  104   a  of the primary MRA cover  104 , and connects with a fuel delivery system  500 ,  600  as discussed hereinbelow. A primary external return line  162  connects, in a manner to be described, with the aforementioned fuel delivery system  500 ,  600  and connects with a primary return port  104   b  of the primary MRA cover  104 . A primary return line  164  connects with the primary return port  104   b  and delivers returned fuel to the primary bucket  112 . 
     The secondary feed line  128  transfers fuel under pressure from the secondary fuel pump  118  to the secondary feed port  108   a  of the secondary MRA cover  108 . A secondary external feed line  166  is connected to the secondary feed port  108   a  of the secondary MRA cover  108 , and connects with aforementioned fuel delivery system  500 ,  600  as discussed hereinbelow. A secondary external return line  168  connects, in a manner to be described, with the aforementioned fuel delivery system  500 ,  600  and connects with a secondary return port  108   b  of the secondary MRA cover  108 . A secondary return line  170  connects with the above mentioned return tee  126 , whereupon the downstream portion of the pump transfer line  122  delivers returned fuel to the secondary bucket  124 . The return tee  126  can be packaged as high as the secondary MRA cover  108 , integrated therewith, integrated with the secondary fuel pump  118 , or eliminated. 
     Referring now to  FIGS. 6 and 7 , the connection of the dual fuel pump fuel extraction system  100  to a fuel delivery system  500 ,  600  will be detailed. 
       FIG. 6  shows a fuel delivery system  500  in which a filter assembly  502  has a housing  504 , an inlet  506 , a fuel filter  508  connected to the inlet, a main fuel line  510  which exits the housing, a pressure regulator  512  teed into the main fuel line downstream of the fuel filter and an outlet  514  connected to the pressure regulator. The external primary feed line  160  and the external secondary feed line  166  both connect to an external feed tee  516 , which, in turn, connects to a common external feed line  518  that connects to the inlet  506 . The external primary return line  162  and the external secondary return line  168  both connect to an external return tee  520 , which, in turn, connects to a common external return line  522  that connects to the outlet  514 . 
     In general operation, fuel is provided by both the primary and secondary fuel pumps  114 ,  118 , filtered at the fuel filter  508  and delivered via the main fuel line  510  to the engine, wherein the pressure regulator  512  maintains proper fuel pressure in the main fuel line. Fuel unused by the engine is returned to the primary and secondary buckets  112 ,  124 . 
     In the special case of operation in which the secondary sump  96  is dry and the primary sump  94  has fuel (as when first built), the primary fuel pump  114  will pump fuel via the primary feed line  116  and primary MRA cover  104  and external primary feed line  160  to the primary external tee  516  and thereupon deliver fuel to the filter assembly  502 , as well as feed fuel back along the external feed line  166 , backwards through the secondary MRA cover  108 , and finally back down through the secondary feed line  128  to the secondary fuel pump  118 , which would then prime. Simultaneously, return fuel would start coming back from the pressure regulator  512  via the external secondary return line  168 , to the secondary MRA cover  108 , down along the secondary return line  170  to the return tee  126 , and, via the downstream portion of the pump transfer line  122 , into the secondary bucket  124 , which would also then be available for the secondary fuel pump  118  to prime. 
       FIG. 7  shows a fuel delivery system  600  in which the filter assembly  602  is as discussed hereinabove with respect to the filter assembly  502  of the fuel delivery system  500  of  FIG. 6 , wherein like numbers refer to like parts, except now the external feed tee is eliminated, and the inlet is now a first inlet  606   a  connecting directly to the primary external feed line  160  and a second inlet  606   b  connecting directly to the secondary external feed line  166 . 
     Referring now to  FIG. 3 , the second embodiment of the dual fuel pump fuel extraction system  200  is as discussed hereinabove with respect to the first embodiment of the duel fuel pump extraction system  100  of  FIG. 2 , wherein like numbers refer to like parts, except now the primary MRA  102 ′ is modified to include an electric auxiliary fuel pump  202  is provided in the primary bucket  112 . The auxiliary fuel pump  202  draws fuel through the strainer  120  in the primary bucket from the primary sump  94  and delivers it the pump transfer line  122 ′ which is modified to connect therewith. The auxiliary fuel pump  202  affirmatively transfers fuel to the secondary bucket  124  so as to mitigate potential fuel vaporization that might otherwise occur at the secondary fuel pump  118 . The aforesaid descriptions relating to connections to the fuel delivery systems  500 ,  600  directly apply and need not be repeated for brevity. 
     Referring now to  FIG. 4 , the third embodiment of the dual fuel pump fuel extraction system  300  is as discussed hereinabove with respect to the first embodiment of the duel fuel pump extraction system  100  of  FIG. 2 , wherein like numbers refer to like parts, except now the secondary MRA  106 ′ is modified to eliminate the return tee  126 , wherein the pump transfer line  122 ″ is now continuous and the secondary return line  170 ′ is modified to discharge fuel into the secondary bucket  124 . The aforesaid descriptions relating to connections to the fuel delivery systems  500 ,  600  directly apply and need not be repeated for brevity. 
     Referring now to  FIG. 5 , the fourth embodiment of the dual fuel pump fuel extraction system  400  is as discussed hereinabove with respect to the third embodiment of the duel fuel pump extraction system  300  of  FIG. 5 , wherein like numbers refer to like parts, except now the primary and secondary MRAs  102 ″,  106 ″ are modified. The primary return line  164 ′ now includes a primary pressure regulator  402 , and terminates in the primary bucket  112  as the fuel discharge therefrom runs the second primary jet pump  144 , rather than a second primary tap line, which is now obviated. The secondary return line  170 ″ now includes a secondary pressure regulator  404 , and terminates in the secondary bucket  124  as the fuel discharge therefrom runs the second secondary jet pump  152 , rather than a second secondary tap line, which is now obviated. 
     Referring now to  FIGS. 8 and 9 , the connection of the dual fuel pump fuel extraction system  400  to a fuel delivery system  700 ,  800  will be detailed. 
       FIG. 8  shows a fuel delivery system  700  in which a filter assembly  702  has a housing  704 , an inlet  706 , a fuel filter  708  connected to the inlet, a main fuel line  710  which exits the housing, and an outlet  712  having a branch connection  714  downstream of the fuel filter to the main fuel line. The external primary feed line  160  and the external secondary feed line  166  both connect to an external feed tee  716 , which, in turn, connects to a common external feed line  718  that connects to the inlet  706 . The external primary return line  162  and the external secondary return line  168  both connect to an external return tee  720 , which, in turn, connects to a common external return line  722  that connects to the outlet  712 . 
     In operation, fuel is provided by both the primary and secondary fuel pumps  114 ,  118 , filtered at the fuel filter  708  and delivered via the main fuel line  710  to the engine, wherein the primary and secondary pressure regulators  402 ,  404  maintain proper fuel pressure in the main fuel line. Fuel unused by the engine is returned to the primary and secondary buckets  112 ,  124 . 
       FIG. 9  shows a fuel delivery system  800  having a filter assembly  802  which is as discussed hereinabove with respect to the filter assembly  702  of the fuel delivery system  700  of  FIG. 8 , wherein like numbers refer to like parts, except now the external feed tee is eliminated, and the inlet is now a first inlet  806   a  connecting directly to the primary external feed line  160  and a second inlet  806   b  connecting directly to the secondary external feed line  166 . 
     The foregoing embodiments may be modified to suit particular applications, wherein several examples thereof are provided hereinbelow. 
     The addition of the auxiliary fuel pump  202  as shown in the dual fuel pump fuel extraction system  200  of  FIG. 3 , may be implemented also in the dual fuel pump fuel extraction system  300  of  FIG. 4  and the dual fuel pump fuel extraction system  400  of  FIG. 5 . 
     The removal of return tee  126  as shown in of the dual fuel pump fuel extraction system  300  of  FIG. 4 , could be implemented in the dual fuel pump fuel extraction system  100  of  FIG. 2 , the dual fuel pump fuel extraction system  200  of  FIG. 3  and the dual fuel pump fuel extraction system  400  of  FIG. 5 . 
     The removal of the pressure regulator from the filter assemblies  702 ,  802  and added to each of the primary and secondary MRAs  102 ″,  106 ″ by primary and secondary pressure regulators  402 ,  404 , as shown in the dual fuel pump fuel extraction system  400  at  FIG. 5 , could be implemented in the dual fuel pump fuel extraction system  100  of  FIG. 2 , the dual fuel pump fuel extraction system  200  of  FIG. 3  and the dual fuel pump fuel extraction system  300  of  FIG. 4 . 
     The tees  126 ,  520  and  516  may be adjusted for desired fuel flow rates, whether being equal or biased to favor the primary or secondary MRAs. 
       FIG. 10  shows a dual fuel pump fuel extraction system  100 ′ which is a modification of the dual fuel pump fuel extraction system  100  of  FIG. 2 , wherein the secondary external feed and return lines  166 ,  168  are obviated. In this case, the secondary feed line  128 ′ is modified to connect to a tee  165  inside the tank shell  82  to the primary feed line  116 ′, and the secondary return line  170 ′″ is modified to connect to a tee  175  inside the tank shell to the primary return line  164 ′. Now a common feed line  185  connects to the primary feed port  104   a  and a common return line  195  connects to the primary return port  104   b .  FIG. 11  depicts a fuel delivery system  500 ′ which is modified from the fuel delivery system  500  of  FIG. 6  to work with the dual fuel pump fuel extraction system  100 ′ of  FIG. 10 , wherein like figures designate like parts. This arrangement would provide the additional benefit of reduced emissions. 
       FIG. 12  shows a dual fuel pump fuel extraction system  100 ″ for interconnecting with the fuel delivery system  500 ′ which is a modification of the dual fuel pump fuel extraction system  100 ′ of  FIG. 10 , wherein the secondary external feed and return lines  166 ,  168  are obviated, as are the secondary return line  170 ′″, the primary return line  164 , and the tees  175  and  126 . Now tee  175 ′ connects the common return line  195  to the pump transfer line  122 . 
       FIG. 13  shows a dual fuel pump fuel extraction system  100 ″ for interconnecting with the fuel delivery system  500 ′ which is a modification of the dual fuel pump fuel extraction system  100 ″ of  FIG. 12 , now including the primary return line  164 . In this regard, the tee  175 ′ of  FIG. 12  is now a cross-tee  175 ″ with pre-calibrated orifices for fuel flow balancing. 
     Further, the fuel delivery systems  500 ,  600 ,  700 ,  800  could be located within the fuel tank shell  82 , having a form suitably packaged for an in-tank environment. 
     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.