Patent Publication Number: US-7588017-B2

Title: Low pressure jet by-pass system for fuel pump

Description:
This application claims the benefit of the earlier filing date of U.S. Provisional Application No. 60/897,133, filed on Jan. 24, 2007, which is hereby incorporated by reference into this specification. 

   FIELD OF THE INVENTION 
   The invention relates to fuel delivery module for automobile vehicles and, more particularly, to operation of a jet assembly associated with a fuel pump of the module. 
   BACKGROUND OF THE INVENTION 
   A fuel delivery module is a device inside a fuel tank that allows a vehicle to perform under conditions of low fuel remaining in the fuel tank. The module includes a reservoir that is kept continuously full by, for example, a jet assembly, even when the remainder of the tank is nearly empty. A fuel pump of the module creates pressure conditions at a low pressure side of the pump to operate the jet assembly. A high pressure side of the fuel pump delivers fuel from the reservoir to an engine. 
   In an electronically pressure controlled fuel system such as an Electronic Returnless Fuel System (ERFS), the pump is supplied a voltage that is pulse width modified (PWM) to control the speed of the pump (this in effect lowers the voltage to the pump as the pump integrates the voltage PWM to a level). When the fuel pump operates at low RPM (e.g., due to low voltage in the range of about 3.5V to 6 V), the pressure at the low pressure side of the fuel pump is low, which is not sufficient to operate the jet assembly. 
   There is a need to ensure that the jet assembly of a fuel delivery module operates when the pressure at the low pressure side of the fuel pump is insufficient to operate the jet assembly. 
   SUMMARY OF THE INVENTION 
   An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is obtained by providing a fuel delivery module for a vehicle including a reservoir constructed and arranged to be mounted in a fuel tank of a vehicle. The reservoir has an opening therein permitting fuel to enter the reservoir. A fuel pump is provided in the reservoir. The fuel pump includes a high pressure portion and a low pressure portion. The fuel pump is constructed and arranged to draw fuel from the reservoir and send fuel from the high pressure portion to an engine of a vehicle. A jet assembly includes a jet nozzle having an inlet fluidly connected with the low pressure portion of the fuel pump and a venturi tube associated with the jet nozzle. The jet assembly is associated with the opening in the reservoir and constructed and arranged so that when a sufficient fuel flow from the low pressure portion of the fuel pump is sent through the jet nozzle and venture tube, fuel is drawn into the reservoir through the opening. By-pass structure is connected between the high pressure portion of the fuel pump and the inlet of the jet nozzle. The by-pass structure is constructed and arranged such that under certain conditions when the flow of fuel from the low pressure portion of the fuel pump alone is insufficient to operate the jet pump assembly, fuel is selectively permitted to flow through the by-pass structure from the high pressure portion of the fuel pump to the inlet of the jet nozzle ensuring that a sufficient flow of fuel is present at the jet assembly to draw fuel into the reservoir. 
   In accordance with another aspect of the invention, a method is provided for ensuring that a jet pump assembly is supplied with a sufficient amount of fuel to operate. The method provides a fuel reservoir having an opening therein. A fuel pump is provided in the reservoir. The fuel pump includes a high pressure portion and a low pressure portion. The fuel pump is constructed and arranged to draw fuel from the reservoir and to send fuel from the high pressure portion to an engine of a vehicle. A jet pump assembly has a jet nozzle having an inlet fluidly connected with the low pressure portion of the fuel pump and a venturi tube associated with the jet nozzle. The jet assembly is associated with the opening in the reservoir and is constructed and arranged so that when a sufficient fuel flow from the low pressure portion of the fuel pump is sent through the jet nozzle and venture tube, fuel is drawn into the reservoir through the opening. Under certain conditions when the flow of fuel from the low pressure portion of the fuel pump alone is insufficient to operate the jet pump assembly, the method includes directing fuel from the high pressure portion of the fuel pump to the inlet of the jet nozzle ensuring that a sufficient flow of fuel is present at the jet assembly to draw fuel into the reservoir. 
   Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, in which: 
       FIG. 1  is a view of a fuel delivery module including a by-pass line in accordance with an embodiment of the invention. 
       FIG. 2  is a partial sectional view of the fuel delivery module of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT 
   With reference to  FIG. 1 , a fuel delivery system for delivering fuel to an engine of a vehicle is shown, generally indicated at  10 , in accordance with the principles of the present invention. The system  10  includes a reservoir  12  that is disposed in a vehicle&#39;s fuel tank  14 . A conventional fuel pump  16  is provided in the reservoir  12  for pumping fuel from the reservoir to the engine (not shown) of the vehicle via line  36 . A flow check valve  17  is provided in line  36 . The fuel pump  16  also operates a jet assembly  18  that draws fuel from the tank  14  into the reservoir  12  to ensure that the reservoir  12  is replenished with fuel. The jet assembly  18  includes a venturi tube  22  associated with a jet nozzle  24  in the conventional manner to draw fuel past a jet valve  20  into the reservoir  12 . 
   More particularly, with reference to  FIG. 2 , as an impeller  26  of the fuel pump  16  rotates, fuel is drawn from the reservoir  12 , through a filter  28  and through pump inlets  30  and  32 . High pressure fuel is delivered from a high pressure portion  34  of the fuel pump  16  to the engine via outlet line  36 . A low pressure portion  38  of the fuel pump  16  sends fuel through the jet nozzle  24 , associated with tube  22 , to draw fuel past valve  20 , associated with opening  42  in the bottom of the reservoir  12 , to replenish fuel in the reservoir  12 . 
   As noted above, when the fuel pump (e.g. impeller  26 ) operates at low RPM with the pump pressure in portion  38  of about 100-300 KPa, there is insufficient fuel flow through the jet nozzle  24  to draw fuel into the reservoir  12 . Thus, in accordance with an embodiment of the invention, by-pass structure, generally indicated at  45 , is provided to by-pass fuel from the high pressure portion  34  of the fuel pump  16  and direct it to the inlet  44  of the jet nozzle  24  to drive the jet assembly  18  with a flow increased from the flow the jet assembly  18  would receive from the low pressure portion  38  alone. In particular, with reference to  FIGS. 1 and 2 , the by-pass structure  45  includes a by-pass line  46  connected between the high pressure portion  34  and the inlet  44  of the jet nozzle  24 . In particular, an end  47  of the by-pass line  46  is coupled with outlet line  36  and the other end  49  of the by-pass line  46  is coupled with a fitting  50  associated with the inlet  44  of the jet nozzle  24 . 
   The by-pass structure  45  also includes a valve  48  ( FIG. 1 ) preferably provided in line  46 . The valve  48  is pressure operated so as to open at a certain low pressure to support priming of the jet nozzle  24  and closes above a certain, higher pressure as the pressure inside the jet main feeding channel is sufficient to operate the jet assembly  18 . Thus, when the valve  48  is opened, fuel in outlet line  36  flows through the by-pass line  46  to the inlet  44  of the jet nozzle  24  to increase fuel flow through the jet nozzle  24 . This fuel flow ensures that the jet assembly  18  will draw fuel into the reservoir  12  even though fuel flow from the low pressure portion  38  of the fuel pump alone is insufficient to operate the jet assembly  18  to replenish fuel in the reservoir  12 . The arrows in  FIG. 2  indicate fuel flow directions. To control the amount of fuel that flows through the bypass line  46  to the inlet of the jet nozzle  24  and to reduce high pressure loss, an orifice  52  can be provided in the bypass line  46  or can be associated with the valve  48 . 
   In the embodiment, the fitting  50  is a T-connection provided in the jet or pump housing to join the flow from the bypass line  46  with the flow from the low pressure portion  38  of the fuel pump  16  at the inlet  44  of the jet nozzle  24 . 
   The valve  48  can be incorporated into a primary portion of the fuel pump  16  or in an existing by-pass port on the pump  16  that is typically used to drive a remote fuel pick-up jet system (not shown). The valve  48  can be a two valve for jet priming only or a three way valve to permit jet priming and high pressure flow. 
   Although a dual channel fuel pump is shown, it can be appreciated that the bypass line  46  can be employed with any type of fuel pump that uses a jet assembly. Thus, whenever pressure to the fuel rail exceeds the feeding pressure of the jet assembly, at least a portion of the higher pressure can be diverted and used to support the jet assembly. 
   The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.