Abstract:
A fuel pump cutoff shuttle valve is located between a multiple fuel pump arrangement. The valve has a first tubular member with a hollow, biased sliding member inside that moves according to the fuel pressures of the pumps. The fuel that flows through the valve member passes out through a valve member central orifice so that the fuel can flow into the second tubular member en route to an engine. When the fuel pressure in a pump greatly exceeds that of another pump on the opposite side of the valve member, the valve member moves and places the valve member central orifice adjacent to the interior wall of the first tubular member, stopping the flow of fuel. Alternatively, the valve member may have an orifice at each end of the valve member to permit a reduced flow of fuel to the engine when fuel is not supplied by the central orifice.

Description:
FIELD OF THE INVENTION  
       [0001]     The teachings of the present invention relate to fluid delivery systems for delivering fluid to an device such as an internal combustion engine. Specifically, the teachings of the present invention relate to a fluid pump cutoff shuttle valve that is spring counterbalanced between fuel flow inputs in a multiple pump arrangement.  
       BACKGROUND OF THE INVENTION  
       [0002]     Major fuel system components used in vehicles for delivering fuel to an internal combustion engine include an engine, a common rail, fuel lines, a fuel pump, and a valve disposed in a fuel line between the engine and the fuel pump.  
         [0003]     While current fuel systems have generally proven to be satisfactory for their applications, each is associated with its share of limitations. One major limitation with many current fuel systems relates to the delivery of fuel from the fuel pump to the engine. More specifically, in a multiple fuel pump arrangement, when the pumping action of one of the pumps is compromised, current valves are incapable of completely terminating fuel flow to the engine. This presents a fuel supply situation in which the air to fuel ratio to the engine is compromised, which results in less than optimal combustion such as lean burn combustion.  
         [0004]     Another limitation of current multiple fuel pump fuel systems is their inability to maintain fuel flow, after the failure of one pump, only to the extent necessary to maintain combustion and permit a vehicle to travel in order to move or to receive service. The inability of dual fuel pump fuel system valves to offer this feature results in vehicle engines that are incapable of operating in order to permit a vehicle to move off of a roadway or reach service.  
         [0005]     What is needed then is a device that does not suffer from the above limitations. This in turn will provide a device that eliminates the problem of fuel flowing through a fuel valve from a first fuel pump of a dual fuel pump arrangement when a second pump ceases to operate, thereby preventing an engine from operating under a less than optimal combustion condition such as lean burn combustion. Furthermore, a device will be provided to successfully stop the flow of fuel from all fuel pumps of a multiple fuel pump arrangement when any of the pumps ceases to operate. Additionally, it is desired that in the event of a failure of a first pump in a dual fuel pump arrangement, the device will permit the second pump to discharge just enough fuel to the engine to support combustion to permit a vehicle to move.  
       SUMMARY OF THE INVENTION  
       [0006]     In accordance with the teachings of the present invention, a fuel pump cutoff shuttle valve for stopping fuel flow to the engine when only one fuel pump of a dual fuel pump arrangement is capable of operation, is disclosed. In alternative teachings, the fuel pump cutoff shuttle valve will maintain a reduced fuel flow to the engine from the total output of one pump in the event that only one fuel pump of a dual fuel pump fuel system is operating.  
         [0007]     In one preferred embodiment, the fuel pump cutoff shuttle valve is situated within a first tubular member that receives liquid fuel from dual fuel pumps and then transfers the liquid fuel to a second tubular member for subsequent transfer to the engine. The shuttle valve mechanism utilizes a hollow valve member within the first tubular member. The hollow valve member receives fuel at each of its ends, each end receiving fuel from a different fuel pump of a dual fuel pump arrangement. During standard operation, when the fuel is being pumped from each fuel pump into the first tubular member with its valve member, the fuel flows are combined and passed through an orifice in the center of the valve mechanism and then into the second tubular member.  
         [0008]     The valve member is centered in the first tubular member by a spring on each side of the valve mechanism if no fuel is flowing. Additionally, constant and equal fuel pressure of each fuel pump assists in keeping the valve member centered. When fuel pressure from one of the pumps drops below that of the other fuel pump, such as when one pump stops operating, the combined force from the pump pressure and the spring on the side of the valve mechanism where the pump is still operating, forces the valve mechanism toward the fuel pump that has experienced a drop in pressure. This causes the valve mechanism with its center orifice to be forced to one side of the first tubular member, thereby completely stopping the flow of fuel from both fuel pumps due to blockage of the orifice by the first tubular member wall. This prevents the engine from experiencing inefficient combustion. That is, if the engine is not receiving the proper flow rate of fuel, the engine cannot support proper combustion, resulting in inefficient combustion. This first embodiment stops the flow of fuel, and thus the engine and potential inefficient combustion.  
         [0009]     In a second preferred embodiment, the valve member has an orifice in each collar located at opposite ends of the valve member. These collar orifices permit a volume of fuel to pass from the valve member in the first tubular member into the second tubular member and then to the engine, even when one fuel pump is not operating. This reduced volume of fuel from one operating pump will permit limited function of a vehicle engine in order to move a vehicle prior to servicing.  
         [0010]     The use of the present invention provides a fuel pump cutoff shuttle valve with a valve member that is capable of moving within a tubular member to prevent the flow of fuel or maintain a reduced flow rate of fuel to an engine when one fuel pump in a dual fuel pump arrangement either stops pumping or becomes impaired. As a result, the aforementioned limitations of available fuel pump systems and associated valves have been substantially reduced.  
         [0011]     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  
       [0012]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0013]      FIG. 1  is a perspective view of a vehicle fuel delivery system and its general location within a vehicle according to teachings of a first embodiment of the present invention;  
         [0014]      FIG. 2  is a top view of a T-joint and shuttle valve according to teachings of the first embodiment of the present invention;  
         [0015]      FIG. 3  is a top view of a T-joint and shuttle valve showing fuel flow inlets and spring forces according to teachings of the first embodiment of the present invention;  
         [0016]      FIG. 4  is a top view of a T-joint and shuttle valve showing how the shuttle moves when the fuel pressure of a first pump is greater than the fuel pressure of a second pump; and  
         [0017]      FIG. 5  is a top view of a T-joint showing fuel orifices in the ends of the shuttle valve according to teachings of a second embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. Moreover, while the teachings of the present invention are described in detail below generally with respect to automotive fuel delivery systems and their association with internal combustion engines, it will be appreciated by those skilled in the art that the teachings of the present invention are clearly not limited to only an automotive fuel system or automotive internal combustion engine fuel system, and may be applied to various other types of fuel systems for other combustion engines such as diesel fuel systems, liquid petroleum (LP) fuel systems, and the like, as further discussed herein.  
         [0019]     Referring to  FIG. 1 , a vehicle  10  is depicted, showing, a vehicle fuel system  20  and its associated parts in accordance with the teachings of the present invention. The fuel system  20  of  FIG. 1  is shown to include a fuel tank  22 , a first fuel pump  24 , a second fuel pump  26 , a first fuel pump fuel line  28 , and a second fuel pump fuel line  30 . The first fuel line  28  and the second fuel line  30  both lead into opposite ends of a T-joint  32 , which is made up of a first tubular member  34  and a second tubular member  36 . As shown in  FIG. 1 , the two-pump fuel system consists of fuel pump  24  and fuel pump  26  to provide fuel to the engine  38 . The fuel flow from both pumps is brought together inside the fuel tank  22  at the T-joint  32  and from there fuel is delivered in a single flow through a fuel line  40  to a fuel rail  42 , or multiple fuel rails, and subsequently, to the engine  38 . At the engine  38 , the fuel is combusted to provide energy to the vehicle  10 .  
         [0020]     The T-joint  32  design incorporates a shuttle valve  42  as shown in  FIG. 2 . The shuttle  44  is positioned between a first fuel inlet  46  and a second fuel inlet  48  by using a first spring  50  and a second spring  52 . The springs  50 ,  52  possess sufficient strength to hold the shuttle  44  in a central position within the first tubular member  34  of the T-joint  32  when the pumps  24 ,  26  are not operating. The first tubular member  34  is joined to the second tubular member  36  to permit fluid to flow between them. Normally liquid fuel flows from the first tubular member  34  into the second tubular member  36 . The second tubular member  36  divides the first tubular member  34  into a first side  56  and a second side  58 . Therefore, when the shuttle  44  is centrally positioned, such as when the fuel pumps  24 ,  26  are not pumping fuel, the shuttle  44  is located such that the orifice  54  of the central portion  64  of the shuttle  44  is directly in line with the central axis of the second tubular member  36  to permit the free flow of fuel into the second tubular member  36 . This also means that the first half  60  of the shuttle  44  resides within the first side  56  of the first tubular member  34 , and the second half  62  of the shuttle  44  resides in the second side  58  of the first tubular member  34 .  
         [0021]     Operation of the shuttle valve  42  will now be explained according to teachings of the first embodiment of the present invention. When both fuel pumps  24 ,  26  are pumping at the same pressure, fuel enters the first tubular member  34  at the first fuel inlet  46  and the second fuel inlet  48  and exits through a single orifice  54  before passing into the second tubular member  36 . The shuttle valve  42  is designed so that as long as fuel pressure on either side of the shuttle  44  is equal, the shuttle  44  will remain in its central position relative to the second tubular member  36 . This means that the central portion  64  of the shuttle  44  is centrally located with respect to the central axis of the second tubular member  36 . This central position is the normal position of the shuttle  44  and does not change unless one of the fuel pumps  24 ,  26  stops operating or experiences a significant decrease or increase in fuel pressure, relative to its counterpart pump.  
         [0022]     Referring to  FIG. 3  and assuming a fuel flow of constant fluid fuel pressure from the fuel pumps  24 ,  26 , fuel flows into the first side  56  of the first tubular member  34  through the first inlet  46  as shown by the arrow  68 , while fuel flows into the second side  58  of the first tubular member  34  through the second fuel inlet  48  as shown by the arrow  70 . The fuel pressure from the first pump  24  exerts a force on the first side  56  of the shuttle  44  as noted by the force arrows  72 ,  74 , while the fuel pressure from the second pump  26  exerts a force on the second side  58  of the shuttle  44  as noted by the force arrows  76 ,  78 . In addition to the force resulting from the fuel pressure, the springs  50 ,  52  also exert a force on their respective sides of the shuttle  44 . Therefore, when fuel flows into the first tubular member  34  and subsequently, into the shuttle  44 , it is forced to exit the shuttle  44  through the orifice  54 . The exiting fuel from the orifice  54 , shown by the flow arrows  80 ,  82 , combines to form a single flow of fuel  84  which continues to the engine  38 . The above depiction represents fuel delivery when the flow of fuel is being delivered at equal and constant pressures from the fuel pumps  24 ,  26 . A different situation presents itself when fuel is not delivered at a constant pressure, as noted in the second embodiment.  
         [0023]     When the pumping action of the fuel pumps  24 ,  26  varies during operation, the difference in fuel pressure causes different forces to act on each side of the shuttle  44 . This disparity in forces causes the shuttle  44  to slide along the inside surface  66  of the first tubular member  34 . Since the first spring  50  and the second spring  52  supply equal forces to the shuttle  44 , the disparity in forces caused by the difference in fuel pressure from the fuel pumps  24 ,  26  is what causes the shuttle  44  to move along the inside surface  66  of the first tubular member  34 .  FIG. 4  is an example of how the shuttle  44  moves when the fuel pressure of the first pump  24  is greater than the second pump  26 , assuming that the second pump  26  significantly reduces its output for some reason.  
         [0024]     As shown in  FIG. 4 , the pressure of the first pump  24  is such that it causes fuel to flow according to flow arrow  86 . The fuel pressure causes a force to be generated, which is combined with the force of the first spring  50  in generating a combined force against the first side  56  of the shuttle  44 . During the time that the first pump is operating, the second pump  26  ceases to pump at the pressure at which the first pump  24  is operating. This reduced flow rate is noted by flow arrow  88 . Due to the reduced flow, the force against the second side  58  of the shuttle  44  is also reduced. The reduced force is noted by the force arrows  94 ,  96 . Because of this disparity in force, the shuttle moves away from the first side  56  and toward the second side  58  of the first tubular member  34 . This change in position of the shuttle  44  is shown in  FIG. 4 .  
         [0025]     At the position of the shuttle  44  in  FIG. 4 , an object of the teachings of the present invention is satisfied. An object of the teachings is to stop the flow of fuel to the engine in the event that one pump in a dual fuel pump fuel system ceases to operate or is significantly different in its output pressure compared to its counterpart pump. As depicted in  FIG. 4 , the flow of fuel  102 ,  104  out of the orifice  54  is directed at the inside surface  66  of the first tubular member  34 . This stops the flow of fuel to the engine  38 , since the seal between the shuttle  44  and the inside surface  66  of the first tubular member  34  prevents the passage of fuel, and with that seal in place, the fuel has no outlet. Stopping the flow of fuel to the engine  38  prevents an undesirable air to fuel ratio during combustion within the engine  38 . As an alternative to this configuration,  FIG. 5  presents a configuration in which an amount of fuel is delivered to the engine  48  even when the pumping efficacy of one pump  26  in a dual pump system  24 ,  26  is compromised.  
         [0026]      FIG. 5  depicts a situation in which an amount of fuel is delivered to the engine  48  even when the pumping effectiveness of one pump  26  in a dual pump system  24 ,  26  is compromised or stops pumping. The reduced flow of fuel is shown by the dashed arrow coming from orifice  108 . As shown in  FIG. 5 , the pressure of the first pump  24  is such that it causes fuel to flow according to flow arrow  86 . The fuel pressure causes a force to be generated, which is combined with the force of the first spring  50  in generating a combined force against the first side  56  of the shuttle  44 . During the time that the first pump is operating, the second pump  26  ceases to pump at the pressure at which the first pump  24  is operating. This reduced flow rate is noted by flow arrow  88 . Due to the reduced flow, the force against the corresponding side of the shuttle  44  is also reduced, which is noted by the force arrows  94 ,  96 . Because of this disparity in force, the shuttle  44  moves away from the first side  56  and toward the second side  58  of the first tubular member  34  as shown in  FIG. 5 .  
         [0027]     At the position of the shuttle  44  in  FIG. 5 , another object of the teachings of the present invention is evident. That object of the teachings is to stop the flow of fuel coming from the orifice  54  in the event that one pump in a dual fuel pump fuel system ceases to operate or is significantly different in its pressure output compared to its counterpart pump. However, the object is compound, and as can be seen in  FIG. 5 , since the shuttle has an orifice  108  in the first side  98  of the shuttle  44 , and an orifice  106  in the second side  100  of the shuttle  44 . These orifices  106 ,  108  are located in the collars at the ends of the shuttle  44  and permit fuel to flow to the engine  48  even when the flow of fuel from the centrally located orifice  54  has been stopped. As seen in  FIG. 5 , the flow of fuel, as noted by the dashed line from the orifice  108 , continues from orifice  108  when fuel is delivered from the first pump  24 , even when the pumping action of the second pump  26  has ceased or the second pump&#39;s pumping pressure has been compromised relative to the first pump  24 . The advantage of this second embodiment is that even though the pumping action of one pump has been compromised, and the main flow of fuel has stopped, that is, the main flow of fuel from the central orifice  54 , the flow coming from a collar orifice  108  permits the engine to operate so that a vehicle can be moved to obtain service or be repositioned.  
         [0028]     Although the second embodiment has been depicted with the first pump  24  as the pump that continues to operate and the second pump  26  as the pump that stops pumping or has its pumping pressure compromised, the opposite could occur and result in the same advantage. That is, the second pump  26  could continue to pump at a steady or constant pressure necessary for approximately 50% of the required engine and vehicle performance, with the first pump  24  experiencing a reduced pumping pressure relative to the second pump  26 . In this situation, the shuttle  44  would be forced toward the first side  56  of the first tubular member  34  and although fuel would stop exiting from the orifice  54  because the orifice  54  would face the inside surface  66  of the first tubular member  34 , fuel would be able to pass through collar orifice  106  because of its alignment with the second tubular member  36 . This second scenario is not shown in the figures since it is a mirror image of  FIG. 5 .  
         [0029]     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.