Patent Publication Number: US-6668806-B2

Title: Fuel pump assembly including a filter outlet to pump inlet isolator

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to automotive engine fuel delivery systems and, in particular, to a fuel pump assembly including a fuel filter outlet to pump inlet isolator. 
     Automotive fuel systems, such as those utilizing gasoline or diesel fuel, are well known. An automotive fuel system includes a fuel tank disposed within an automobile body for storing fuel for the internal combustion engine. The fuel tank is typically constructed of steel and is connected to an inlet of a fuel pump. The fuel pump is either a centrifugal or a positive displacement type pump that is driven by an electric motor and an outlet of the fuel pump is connected to a fuel delivery system, typically a fuel injection system or a carburetor. The piping connection from the fuel tank to the inlet of the fuel pump typically includes a fuel filter that protects the internal components of the fuel pump from foreign object damage. 
     Improvements in manufacturing led to the fuel pump and fuel filter being manufactured as part of a fuel delivery module, which is disposed within the fuel tank. These fuel delivery modules are advantageous because the modules may be preassembled and inserted into the fuel tank later in the assembly process. In addition, fuel delivery modules may be constructed of lighter and cheaper materials, such as plastic. The fuel delivery modules typically attach the outlet of the fuel filter directly to the inlet of the fuel pump, which is mounted in the fuel delivery module. The fuel delivery module, in turn, is mounted on a wall of the fuel tank. 
     Fuel tanks, especially steel fuel tanks, having the fuel pump or a fuel delivery module disposed therein have notoriously had problems with noise, vibration and harshness (NVH). Vibration problems, in particular, are compounded when the fuel filter, in direct contact with the fuel pump and either the walls of the module or the fuel tank, acts as a conduit through which the vibratory energy travels. Prior art fuel systems have attempted to solve these problems, including the use of damping sleeves, damping seals, damping bushings, and other damping elements, among others. Vibration problems, however, continue to plague fuel systems having integral fuel delivery modules disposed within the fuel tank. 
     Furthermore, recent developments in noise dampening and insulation have resulted in automobile interiors being much quieter than in previous years. As the noise in the automobile interior is reduced, the driver of the vehicle is now aware of more NVH sources, such as vibration from the automobile&#39;s fuel system, that were inaudible in prior art automobiles. The vibration is distracting to the driver and reduces ride comfort, which in turn reduces the automobile quality and overall customer satisfaction with the automobile. 
     It is a continuing goal in fuel system design to reduce the amount of NVH in the fuel system. It is an object of the invention, therefore, to provide a fuel delivery system that reduces the NVH of prior art fuel systems and does not produce an objectionable amount of noise for the driver of the automobile. 
     SUMMARY OF THE INVENTION 
     The present invention concerns a fuel filter outlet to pump inlet isolator for use in an automotive fuel system. The fuel system includes a preferably steel fuel tank disposed within an automobile body for storing and providing fuel to the automobile&#39;s internal combustion engine. An aperture in the exterior surface of the fuel tank receives a fuel delivery module. 
     The fuel delivery module includes a generally tubular, preferably plastic housing. The housing is preferably sized to conform to the aperture in the exterior surface of the fuel tank. The housing performs a variety of functions, including providing a vessel for storing fuel to be used for starting the automobile and providing a pressure vessel for pressurized fuel, after it has left the outlet of the fuel pump, to be stored prior to delivery to the engine. A primary filter having an inlet end and an outlet end extends radially outwardly from the housing. The primary filter functions as the first means for preventing contamination of the automobile&#39;s fuel supply by not allowing solid particles to pass from the interior of the fuel tank to the interior of the housing. 
     The housing receives a fuel pump having an inlet connection and an outlet connection and is typically driven by an electric motor. A plurality of electrical connections for the fuel pump motor are disposed on an upper surface of the housing for providing electrical power to the fuel pump motor. The outlet of the fuel pump is connected to provide fuel to a fuel injector or a carburetor at the engine. Optionally, a fuel return line is connected to a top portion of the housing for recirculating unused fuel, favorably reducing fuel wastage. 
     The housing also receives a fuel pump filter, which is preferably a screen filter having an fuel inlet and a fuel outlet. The fuel pump filter preferably screens smaller particles than the primary filter on the exterior of the housing. The fuel pump filter is preferably constructed of plastic or similar material and is located adjacent a lower portion of the fuel pump. The inlet of the fuel pump filter is open to the interior of the housing. The outlet of the fuel pump filter is preferably a portion of pipe that is connected to the inlet of the fuel pump. 
     An isolator according to the present invention connects the outlet of the fuel pump filter to the fuel pump inlet. The insertion of the isolator as part of the fuel delivery module prevents direct contact between the fuel pump and the fuel pump filter, advantageously limiting transfer of vibratory energy from the fuel pump to the housing. The isolator preferably possesses vibration dampening properties and is preferably a piece of flexible tubing or piping having an inlet end and an outlet end that is sized to carry the fuel volume required by the fuel pump. The inlet end of the isolator is connected to the outlet of the fuel pump filter. The outlet end of the isolator is connected to the inlet of the fuel pump. The present invention advantageously incorporates a step manifold as part of a lower surface of the fuel delivery module in order to create the needed space for the addition of the isolator. 
     The present invention isolates the fuel pump from the fuel pump filter by inserting an isolator between the pump inlet and the fuel pump filter as part of the fuel delivery module. The positioning of this isolator advantageously reduces the transfer of energy from the fuel pump via vibration and pressure pulsations to both the fuel delivery module and the steel fuel tank. 
     The present invention has shown the ability to reduce by half the amount of noise emanating from the prior art fuel pump, fuel delivery module, and fuel tank, making the sound subjectively non-existent. 
     The isolator according to the present invention may be an integral component of the fuel pump filter or a separate component of the fuel delivery module, advantageously providing more manufacturing options for the fuel delivery module. Not only does the isolator of the present invention act as a dampening device but the isolator is also a conduit for the fuel and is thus a integral component of both the fuel system and the fuel delivery module. 
     The present invention may be advantageously used with fuel delivery modules with or without fuel return lines. Furthermore, the present invention may be advantageously used with several models of fuel tanks, fuel pumps, and fuel delivery modules currently in production where it is desirable to reduce the amount of NVH of the fuel system, all while remaining within the scope of the invention. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
     FIG. 1 is a schematic view of a prior art system for providing fuel to an internal combustion engine, showing the location of the fuel delivery module in relation to the fuel tank and internal combustion engine; 
     FIG. 2 is a perspective view of a fuel delivery module in accordance with the present invention; and 
     FIG. 3 is a perspective view of a fuel pump and fuel filter including an isolator in accordance with the present invention; 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, a prior art fuel system is indicated generally at  10 . The fuel system  10  provides fuel (not shown) from a fuel tank  12  to an internal combustion engine  14 . The fuel tank  12  and the engine  14  are preferably disposed within the body of an automobile  16 . 
     The fuel tank  12  is preferably constructed of steel or a similar material. 
     A fuel delivery module  18  is disposed within the fuel tank  12 . The fuel delivery module  18  includes an inlet  20  adjacent to a lower surface of the fuel tank  12  and an outlet  22  adjacent to an upper surface of the fuel tank  12 . The outlet  22  is connected to a fuel supply line  24  that extends to a fuel delivery system  26 , such as a fuel injector or carbeurator of the engine  14 . A primary filter  26  is attached to the inlet  20  of the fuel delivery module  18  adjacent to a bottom surface of the fuel delivery module  18 . 
     Referring now to FIG. 2, a fuel delivery module in accordance with the present invention is indicated generally at  28 . The fuel delivery module  28  is received in a fuel tank (not shown) and preferably extends adjacent to a lower interior surface of the fuel tank. The fuel delivery module  28  includes a generally tubular housing  30  having a closed lower end  32  and a closable upper end  34  that encloses the interior (not shown) of the fuel delivery module  28 . The housing  30  is preferably constructed of plastic or similar lightweight material. A primary filter  36  is mounted to and extends radially outwardly from the lower end  32  of the housing  28 . The primary filter  36  is preferably constructed of a mesh plastic or similar material for preventing particles contained in the fuel and the fuel tank from entering the fuel pump, outlined in more detail below. A fuel outlet conduit  38 , a fuel return conduit  40 , and a lower electrical connector  42  each extend upwardly from the upper end  34  of the housing  30 . 
     The fuel outlet conduit  38  and the fuel return conduit  40  each extend through a lower surface  44  and an upper surface  46  of an upper mounting flange  48 , which is preferably sized to cooperate with an aperture (not shown) in a wall of a fuel tank, such as the fuel tank  12  of FIG.  1 . The fuel outlet conduit  38  extends to an outlet fitting  50 , which further extends to the fuel supply system (not shown) of an internal combustion engine (not shown) of an automobile (not shown). The fuel return conduit  40  extends to a return fitting  52 , which is attached to piping (not shown) from the fuel return portion of the fuel supply system. Alternatively, the fuel delivery system does not include a fuel return portion and no fuel return conduit  40  extends from the upper end  32  of the housing  28  and no return fitting  52  extends from the upper surface  46  of the upper flange  48 . 
     A plurality of electrical wires  54  extends from the lower electrical connector  42  to an upper electrical connector  56 . The upper electrical connector  56  is mounted on the lower surface  44  of the upper flange  48 . The upper electrical connector  56  connects to a wire bundle  58 , which further extends and is connected to an electrical power supply, such as an alternator (not shown) or a battery (not shown) of the automobile. 
     Referring now to FIG. 3, a fuel pump assembly is indicated generally at  60 . The fuel pump assembly  60  is received in the interior (not shown) of the fuel delivery module housing  30 . The fuel pump assembly  60  includes a generally tubular pump body  62  that receives an electrical pump motor (not shown). The pump body  62  is preferably constructed of steel or similar material. A shaft (not shown) extends from the motor to drive a pump impeller (not shown) for supplying pressurized fuel to the fuel system of the automobile. An electrical connector  64  extends from an upper surface of the pump body  62  and is connected to electrical wires (not shown) extending from the lower electrical fitting  42  for supplying electrical power to the pump motor. 
     An isolator  66  having an inlet  68  end and an outlet end  70  extends from a bottom surface of the pump body  62 . The isolator  66  is preferably a piece of flexible tubing or piping possessing vibration dampening properties, such as rubber, neoprene, or the like. The isolator  66  is preferably sized to accommodate a predetermined amount of fuel as required by the fuel pump assembly  60 . The outlet  70  of the isolator  66  is preferably attached to one end of an inlet nipple (not shown) extending from the bottom surface of the pump body  62 . The other end of the inlet nipple is attached to a piping inlet (not shown) of the pump impeller. 
     An elongated secondary filter  72  for the fuel pump assembly  60  is mounted to the inlet end  68  of the isolator  66 . The secondary filter  72  is preferably constructed of a mesh plastic or similar material for preventing particles contained in the fuel and the fuel tank from entering the fuel pump assembly  60  and includes an inlet  74  and an outlet  76 . The outlet  76  of the secondary filter  72  is connected to the inlet  68  of the isolator  66 . The plastic mesh of the secondary filter  72  preferably screens smaller particles than does the primary filter  36  for the fuel delivery module  28 . 
     A pump outlet  78  extends from the upper surface of the pump body  62 . The pump outlet  78  is attached to a piping outlet (not shown) of the pump impeller in the interior of the pump body  62 . The pump outlet  78  is connected (not shown) at an upper end to the fuel outlet conduit  38  for supplying pressurized fuel to the fuel supply system. 
     In operation, fuel is drawn from the fuel tank through the primary filter  36  and into the interior of the fuel delivery module housing  30 . The fuel is then routed from the inlet  74  and to the outlet  76  of the secondary filter  72  and from the inlet end  68  and to the outlet end  70  of the isolator  66 . The fuel then enters the inlet piping of the pump impeller, is raised to a higher pressure by the pump impeller, and exits through the pump outlet  78 . The fuel then enters the fuel outlet conduit  38 , is routed to the outlet fitting  50 , the fuel supply system and, ultimately, the internal combustion engine. 
     As an example, the isolator  66  was tested with a prior art fuel pump, part number VP2F1J-9350-CA, available from Ford Motor Company. As installed on this pump, the isolator  66  was constructed of flexible tubing having a length of approximately 12 to 16 millimeters (mm), an inside diameter of approximately 7 mm, and an outside diameter of approximately 12 mm. If installed between a different fuel pump and fuel filter, the isolator  66  could have other lengths or diameters as required by the respective inlets and outlets of the fuel filter and the fuel pump. 
     During testing of the VP2F1J-9350-CA pump, baseline decibel measurements were first taken with the pump connected directly to the filter. The average decibel reading after three runs was 45.5 dB. The isolator  66  was then installed between the pump and the fuel filter and decibel measurements taken again. The average decibel reading after three runs with the isolator  66  installed on the pump was 21.6 dB, equating to an unexpected drop of more than 23 dB and making the sound from the VP2F1J-9350CA pump subjectively non-existent. 
     In accordance with the provisions of the patent statutes, the present invention been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.