Abstract:
A by-pass fuel system in which the plumbing of the fuel pump module is configured to ensure by-pass strained (and filtered) fuel remains separate from the reservoir fuel after by-pass such that it is not re-strained before re-entry to the fuel pump. The anti-clogging fuel pump module is plumbed such that the by-pass strained fuel is directed to the fuel pump separately with respect to the reservoir fuel, wherein it never mixes with reservoir fuel except after the reservoir fuel has passed through the strainer. Thus, the by-pass strained fuel only mixes with strained fuel from the strainer before its entry to the fuel pump. Accordingly, only reservoir fuel in the fuel pump module is passed through the strainer, whereby the clogging rate of the strainer is minimized.

Description:
TECHNICAL FIELD 
     The present invention relates to fuel pump modules which are interfaced with fuel tanks for motor vehicles, and more particularly to a by-pass fuel system in which strained (and filtered) by-pass fuel is sent directly to the fuel pump without being re-strained. 
     BACKGROUND OF THE INVENTION 
     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 outershell. 
       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 outershell  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 . 
     The fuel pump module  14  is part of a by-pass fuel system. With respect to by-pass fuel systems, there are feed and by-pass fuel lines which loop the fuel back to the fuel pump module or loop the fuel within the fuel pump module. The term “by-pass fuel system” refers to both “return fuel systems” and “mechanical returnless fuel systems”. In the case of returnless fuel systems, a fuel pressure regulator is included with the by-pass fuel loop, being located within the fuel pump module. 
       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 return fuel system. A module reservoir  22  is defined by a plastic module sidewall  20   a . A fuel pump  24  draws reservoir fuel F R  through a strainer  26  in the module reservoir, and the strained fuel F S  is then pumped by the fuel pump  24 , and the strained pumped fuel F P  is then delivered to the engine  40  via an inline fuel filter  28  and feed fuel line  30 . 
     The by-pass fuel system continuously pumps fuel, and any amount not utilized by the engine is returned as a by-pass strained fuel F B  to the fuel pump module  20  by an intersecting by-pass fuel line  32  with a fuel pressure regulator  34  located between the fuel pump  24  and the engine  40 . The by-pass strained fuel F B  is dumped via a standpipe  36  into the module reservoir  22 . In this regard, because the by-pass strained fuel F B  dumpingly mixes with the reservoir fuel F R  already in the module reservoir, it becomes no longer separate as a uniquely identifiable entity and becomes merely a mixed aspect of the reservoir fuel F R  component, wherein all of the reservoir fuel must be strained before entry to the fuel pump. 
     In that a conventional fuel pump module of a by-pass fuel system dumps and mixes the by-pass strained fuel F B  with the reservoir fuel F R , all fuel entering into the fuel pump must be strained in order to remove any contaminants from the fuel regardless of the fact that some of the fuel may have been previously strained. This requirement to strain all fuel entering the fuel pump irrespective of past strain history of the fuel requires the fuel pump to work harder than it might otherwise have to if somehow the strained fuel could remain separate. Further, the mixing of the by-pass strained fuel F B  with the reservoir fuel F R  causes the strainer to pass therethrough more fuel, with attendant clogging aspects, than would otherwise be necessary if somehow the strained fuel could remain separated from the reservoir fuel and somehow be able to pass to the fuel pump without being re-strained. 
     Accordingly, it would be desirable for by-pass fuel systems if somehow the by-pass strained fuel could remain separate from the reservoir fuel after by-pass such that it would not have to be re-strained before entry to the fuel pump. 
     SUMMARY OF THE INVENTION 
     The present invention is a by-pass fuel system in which the plumbing of the fuel pump module is configured such that the by-pass strained fuel remains separate from the reservoir fuel after by-pass such that it is not re-strained before re-entry to the fuel pump. 
     The anti-clogging fuel pump module according to the present invention is plumbed to ensure the by-pass strained (and filtered) fuel is directed to the fuel pump separately with respect to the reservoir fuel, wherein it never mixes with reservoir fuel except after the reservoir fuel has passed through the strainer. Thus, the by-pass strained fuel only mixes with strained fuel from the strainer before its entry to the fuel pump. Accordingly, only reservoir fuel in the fuel pump module is passed through the strainer, whereby the clogging rate of the strainer is minimized. 
     A benefit of the anti-clogging fuel pump module is that it allows the fuel pump to preferentially utilize the by-pass strained fuel, thereby reducing the relative flow rate of the fuel pump reservoir fuel (unstrained fuel) through the strainer attached to the fuel pump. This reduction in the reservoir fuel (unstrained and potentially “dirty” fuel) flow through the strainer will reduce the capture of fine sediment particles in and on the strainer, wherein such particles tend to clog the strainer. Other benefits of the present invention include a potential cleaning effect of the outer surface of the strainer by flow of the by-pass strained fuel, a potential reduction of fuel pump wear, an improvement in the hot fuel handling capabilities of the fuel pump by increasing the fuel pressure (reducing fuel vapor formation in the fuel pump) at the inlet of the pump, and reduction of the volatility of the fuel due to direct recirculation of strained fuel and vapor stripping of the fuel being pumped. 
     Accordingly, it is an object of the present invention to provide a by-pass fuel system in which the plumbing of the fuel pump module is configured such that the by-pass strained fuel remains separate from the reservoir fuel after by-pass such that it is not re-strained before re-entry to the fuel pump. 
     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 
         FIG. 1  is a perspective view of a fuel tank, showing in particular a fuel pump module interfaced therewith. 
         FIG. 2  is a schematic representation of a prior art fuel pump module for a fuel tank of a by-pass fuel system. 
         FIG. 3A  is a schematic representation of a first example of a preferred embodiment of the anti-clogging fuel pump module for a fuel tank of a by-pass fuel system according to the present invention. 
         FIG. 3B  is a schematic representation of a second example of the preferred embodiment of the anti-clogging fuel pump module for a fuel tank of a by-pass fuel system according to the present invention. 
         FIG. 3C  is a schematic representation of a third example of the preferred embodiment of the anti-clogging fuel pump module for a fuel tank of a by-pass fuel system according to the present invention. 
         FIG. 3D  is a schematic representation of a fourth example of the preferred embodiment of the anti-clogging fuel pump module for a fuel tank of a by-pass fuel system according to the present invention. 
         FIG. 4  is a partly sectional side view of an implementation of the preferred embodiment of the anti-clogging fuel pump module for a fuel tank of a by-pass fuel system according to the present invention. 
         FIG. 5  is an exploded view of the anti-clogging fuel pump module of  FIG. 4 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the Drawing,  FIGS. 3A through 5  depict various aspects of an anti-clogging fuel pump module  100  for a fuel tank of a by-pass fuel system, wherein the by-pass strained fuel remains separate from the reservoir fuel (i.e., it retains its unique identity) after by-pass such that it is not mixed with the reservoir fuel upstream of the strainer, but rather mixed with strained fuel downstream of the strainer before delivery to (i.e., upstream of) the fuel pump. 
     Referring now to  FIG. 3A , a first schematic example of the anti-clogging fuel pump module  100 ,  100   a  is depicted, utilized as for example in the manner of fuel pump module  14  in  FIG. 1  with respect to a fuel tank of a by-pass fuel system. 
     The fuel pump module  100   a  has a module reservoir  102   a  defined by a plastic module sidewall  104   a . Strained fuel F S  which has passed through a strainer  108   a  is pumped by a fuel pump  106   a , and delivered as strained pumped fuel F P  to the engine  120   a  via an in-line fuel filter  118   a  and feed fuel line  110   a , wherein strained pumped fuel not utilized by the engine is by-passed, via an intersecting by-pass fuel line  112   a  with a fuel pressure regulator  122   a  located between the fuel pump  106   a  and the engine  120   a , as by-pass return strained fuel F B . 
     The strainer  108   a  has two ports, a first port  114   a ′ for delivery of strained fuel F S  to the fuel pump  106   a , and a second port  114   a ″ which communicates with a standpipe  116   a  which is, in turn, connected to the by-pass fuel line  112   a . The second port communication is plumbed so as to be exclusive with respect to the by-pass strained fuel F B  (i.e., there is no communication with the reservoir fuel F R ). Strained pumped fuel F P  not used by the engine is by-passed, through the by-pass fuel line  112   a  and the pressure regulator  122   a , into the standpipe  116   a  and then into an internal channel  108   a ′ of the strainer  108   a , whereby the by-pass strained fuel F B  is directly recirculated into the fuel pump  106   a . Reservoir (bulk) fuel F R  is also drawn into the strainer  108   a  to augment the fuel flow requirement of the engine. All the components are contained within the fuel pump module reservoir  102   a  with the possible exception of the pressure regulator which may be located remotely in the vehicle architecture. 
     Referring now to  FIG. 3B , a second schematic example of the anti-clogging fuel pump module  100 ,  100   b  is depicted, utilized as for example in the manner of fuel pump module  14  in  FIG. 1  with respect to a fuel tank of a by-pass fuel system. 
     The fuel pump module  100   b  has a module reservoir  102   b  defined by a plastic module sidewall  104   b . Strained fuel F S  which has passed through a strainer  108   b  is pumped by a fuel pump  106   b , and delivered as strained pumped fuel F P  to the engine  120   b  via an in-line fuel filter  118   b  and feed fuel line  110   b , wherein strained pumped fuel not utilized by the engine is by-passed, via an intersecting by-pass fuel line  112   b  with fuel pressure regulator  122   b  located between the fuel pump  106   b  and the engine  120   b , as by-pass return strained fuel F B . 
     The strainer  108   b  has two ports, a first port  114   b ′ for delivery of strained fuel F S  to the fuel pump  106   b , and a second port  114   b ″ which communicates with a standpipe  116   b  which is, in turn, connected to the by-pass fuel line  112   b . The second port communication is plumbed so as to be exclusive with respect to the by-pass strained fuel F B  (i.e., there is no communication with the reservoir fuel F R ). Strained pumped fuel F P  not used by the engine is by-passed, through the by-pass fuel line  112   b  and the fuel pressure regulator  122   b , into the standpipe  116   b  and then into a strained-fuel-side internal channel  108   b ′ of the strainer  108   b , whereby the by-pass strained fuel F B  is directly recirculated into the fuel pump  106   b . Reservoir (bulk) fuel F R  is also drawn into the strainer  108   b  to augment the fuel flow requirement of the engine. 
     The fuel pump module  100   b  differs from the fuel pump module  100   a  in that the second port  114   b ″ is inserted sealingly by a seal  118   b  into the standpipe  116   b , thereby allowing the by-pass fuel flow to be directed along the entire internal channel  108   b ′ of the strainer  108   b , wherein the strainer is also completely contained within the module reservoir. 
     Referring now to  FIG. 3C , a third schematic example of the anti-clogging fuel pump module  100 ,  100   c  is depicted, utilized as for example in the manner of fuel pump module  14  in  FIG. 1  with respect to a fuel tank of a by-pass fuel system. 
     The fuel pump module  100   c  has a module reservoir  102   c  defined by a plastic module sidewall  104   c . Strained fuel F S  which has passed through a strainer  108   c  is pumped by a fuel pump  106   c , and delivered as strained pumped fuel F P  to the engine  120   c  via an inline fuel filter  122   c  and feed fuel line  110   c , wherein strained pumped fuel not utilized by the engine is by-passed, via an intersecting by-pass fuel line  112   c  with a fuel pressure regulator  122   c  located between the fuel pump  106   c  and the engine  120   c , as by-pass strained fuel F B . 
     The strainer  108   c  has a single port  114   c  for delivery of strained fuel F S  to the fuel pump  106   c  via a fitting  116   c . In the fuel pump module  100   c , rather than a standpipe, a by-pass tube  118   c , which may be flexible or rigid, directly connects to the fitting  116   c  downstream of the strainer  108   c  and upstream of the fuel pump  106   c , via a side port  120   c , wherein there is no communication with the reservoir fuel F R . Strained pumped fuel F P  not used by the engine is by-passed, through the by-pass fuel line  112   c  and the fuel pressure regulator  122   c , into the by-pass tube to the fuel pump  106   c , whereby the by-pass strained return fuel F B  is directly recirculated into the fuel pump. Reservoir (bulk) fuel F R  is also drawn into the strainer  108   c  to augment the fuel flow requirement of the engine, wherein the strainer is also completely contained within the module reservoir. 
     Referring now to  FIG. 3D , a fourth schematic example of the anti-clogging fuel pump module  100 ,  100   d  is depicted, utilized as for example in the manner of fuel pump module  14  in  FIG. 1  with respect to a fuel tank of a by-pass fuel system. 
     The fuel pump module  100   d  has a module reservoir  102   d  defined by a plastic module sidewall  104   d . Strained fuel F S  which has passed through a strainer  108   d  is pumped by a fuel pump  106   d , and delivered as strained pumped fuel F P  to the engine  120   d  via an in-line fuel filter  122   d  and feed fuel line  110   d , wherein strained pumped fuel not utilized by the engine is by-passed, via an intersecting by-pass fuel line  112   d  with fuel pressure regulator  122   d  located between the fuel pump  106   d  and the engine  120   d , as by-pass strained fuel F B . 
     The strainer  108   d  communicates with a strainer fitting  114   d  through which is provided delivery of strained fuel F S  to the fuel pump  106   d . In the fuel pump module  100   d , a standpipe  116   d  connects to the by-pass fuel line  110   d  and an external channel  122   d . The external channel  122   d , in turn, connects to the strainer fitting  114   d . Strained pumped fuel F P  not used by the engine is by-passed through the by-pass fuel line  112   d  and fuel pressure regulator  122   d  into the strainer fitting  114   d  to the fuel pump  106   d , whereby the by-pass strained fuel F B  is directly recirculated into the fuel pump. Reservoir (bulk) fuel F R  is also drawn into the strainer  108   d  and then into the strainer fitting to augment the fuel flow requirement of the engine, wherein the strainer is also completely contained within the module reservoir, and wherein the strainer is also completely contained within the module reservoir. 
     In the examples of  FIGS. 3A through 3D , heat transfer plumbing, or a heat exchanger may be provided in the module reservoir as needed according to standard practices in the art in order to eliminate fuel heating and/or aging effects. 
     Turning attention now to  FIGS. 4 and 5 , an anti-clogging fuel pump module  200  is depicted, which is an implementation of the anti-clogging fuel pump module  100   c  of  FIG. 3C . 
     The fuel pump module  200  has a module reservoir  202  defined by a plastic module sidewall  204 . Strained fuel F S  which has passed through a strainer  208  is pumped by a fuel pump  206 , and delivered as strained pumped fuel F P  to the engine via a feed fuel line  210  and in-line filter (not shown), wherein strained pumped fuel not utilized by the engine is by-passed, via an intersecting by-pass fuel line  212  located between the fuel pump  206  and the engine (not shown), as by-pass strained fuel F B . 
     The strainer  208  delivers strained fuel F S  to the fuel pump  206  via a strainer cup  216 . A by-pass tube  218 , which is in this case is rigid, directly connects to the strainer cup  216  downstream of the strainer  208  and upstream of the fuel pump  206 , wherein there is no communication with the reservoir fuel F R . Strained pumped fuel F P  not used by the engine is by-passed, via a pressure regulator  222 , through the by-pass tube  218  to the fuel pump  206 , whereby the by-pass strained fuel F B  is directly recirculated into the fuel pump. Reservoir (bulk) fuel F R  is also drawn into the strainer  208  to augment the fuel flow requirement of the engine, wherein the strainer is also completely contained within the module reservoir. 
     As shown at  FIG. 5 , which is an exploded view of  FIG. 4 , additional parts include: a flange assembly  224 , a delivery hose  226 , a return hose  228 , a float-type fuel level sensor assembly  230 , a supply jet assembly  232 , a supply jet hose  234 , a protector strainer and check valve  236  of the strainer, and a reservoir protector strainer  238 . 
     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.