Abstract:
A fuel delivery module for supplying fuel to an automobile is disclosed. The fuel delivery module has a receptacle for containing a supply of fuel. Further, the receptacle has a curved sidewall. A pump is positioned within the receptacle wherein the pump generates an acoustical wave having a known frequency. The pump having a pump inlet and wherein the pump inlet is located a 1/4 wavelength of the acoustical wave from the curved sidewall. A receptacle lid is configured to mate with the receptacle to define a closed volume.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates to fuel delivery systems for an automobile and to systems and methods for reducing or eliminating noise generated by the fuel pump of the fuel delivery system.  
         BACKGROUND  
         [0002]    Conventional fuel delivery systems in automobiles today include a fuel tank and a fuel delivery module (FDM) positioned within the tank. The fuel delivery module, typically, fills with fuel and the fuel is then evacuated from the FDM pumped to the vehicle&#39;s engine. Typically, a turbine style pump contained within the fuel delivery module provided the pumping action. While the design and performance characteristics of the pump are well suited for this application, the nature of the design can lead to high frequency noise problems. For example, at certain engine operating conditions such as at engine idle, the pump can produce tones loud enough to be heard by the vehicle occupant. Generally, the source of the high frequency noise is the pump&#39;s impeller. The impeller typically has a high number of teeth, such as 47 teeth. Moreover, the pump rotates at 4000 to 5000 rpm at engine idle, thus tones in the 3100 to 3900 hertz range are produced. Unfortunately, this range is well separated and easily distinguishable from engine noise and is also in the most sensitive frequency range of human hearing. Additionally, harmonics of the impeller noise are also within the range of human hearing.  
           [0003]    Prior art methods and systems directed to reducing the. noise generated by the pump&#39;s impeller have focused on redesigning the impeller. While this effort has resulted in some noise reduction, the efforts often only result in a shift of the frequency of the noise.  
           [0004]    The pressure pulsations of the pump originating at the impeller have multiple paths of radiation that can lead to sound generation. For example, the pump vibration may be transferred to the FDM and then to the tank which is a large radiating surface. Another common path is through the fluid or fuel. More specifically, the impeller causes pressure pulsations at the pump&#39;s inlet that propagate through the fluid or fuel to the walls of the FDM. The fluid borne pulsations make the tank radiate sound much the same way as the structure borne vibration. However, since the pump is typically vibration isolated, the fluid borne path can be more efficient and thus more noticeable to a vehicle occupant.  
           [0005]    Thus, there is a need for a new and improved system and method for reducing or eliminating fluid borne noise. The new and improved system and method should reduce fluid borne noise within a fuel delivery system without significantly increasing cost and complexity to the system.  
         SUMMARY  
         [0006]    in an aspect of the present invention a fuel delivery module for supplying fuel to an automobile is provided. The fuel deliver module has a receptacle for containing a supply of fuel, the receptacle having a curved sidewall. A pump is positioned within the receptacle wherein the pump generates an acoustical wave having a known frequency. The pump having a pump inlet and wherein the pump inlet is located a 1/4 wavelength of the acoustical wave from the curved sidewall. A receptacle lid is provided and is configured to mate with the receptacle to define a closed volume.  
           [0007]    In another aspect of the present invention, the module includes an inlet tube coupled to the pump inlet and a filter coupled to the pump inlet.  
           [0008]    In yet another aspect of the present invention, the receptacle lid is positioned at a 1/4 of the wavelength from the bottom of the receptacle and the pump inlet is positioned at a center of a circle defining the curvature of the sidewall.  
           [0009]    In still another aspect of the present invention, the sidewall is spherical.  
           [0010]    These and other aspects and advantages of the present invention will become apparent upon reading the following detailed description of the invention in combination with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0011]    [0011]FIG. 1 is a perspective view of a fuel delivery system, in accordance with the present invention;  
         [0012]    [0012]FIG. 2 is a plan view of a receptacle of a fuel delivery module, in accordance with the present invention;  
         [0013]    [0013]FIGS. 3 and 4, are plan and cross-sectional views of a receptacle and pump of a fuel deliver module, in accordance with the present invention;  
         [0014]    [0014]FIG. 5 is a plan view of the receptacle and pump of the fuel deliver module illustrating a semi-spherical sidewall portion disposed opposite the inlet aperture, in accordance with the present invention; and  
         [0015]    FIGS.  6  is a plan view of an alternate embodiment of the receptacle illustrating a corrugated sidewall portion disposed opposite the inlet aperture, in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]    Referring now to FIG. 1, a fuel delivery system  10  for supplying fuel to a vehicle&#39;s engine  11  is schematically represented, in accordance with the present invention. Fuel delivery system  10  includes a fuel tank  12  and a fuel delivery module (FDM)  14 . Fuel delivery module  14  is disposed within fuel tank  12  and generally attaches to a top surface  16  and a bottom surface  18  of a fuel tank  12 . Typically, fuel delivery module  14  includes a float  20  and a float arm  22  for detecting a fuel level within tank  12 , as well known in the art. Further, fuel delivery module  14  includes a fuel pump  24  for evacuating fuel drawn into a receptacle  26  of fuel delivery module  14 .  
         [0017]    Referring now to FIG. 2, a plan view of receptacle  26  of fuel delivery module  14  is further illustrated, in accordance with the present invention. Receptacle  26  generally includes curved sidewalls  28  and in an embodiment straight sidewalls  30  and  32 . Straight sidewalls  30  and  32  generally project inward at right angles to curved sidewalls  28 . While straight sidewalls  30  and  32  are not a critical aspect of the present invention, walls  30 ,  32  defines a pocket into which pump  24  is positioned. Further, a receptacle bottom  34  is integrally formed with curved sidewalls  28  and straight sidewalls  30  and  32 .  
         [0018]    Referring now to FIG. 3, a plan view of receptacle  26  is illustrated with pump  24  installed therein, in accordance with the present invention. Pump  24  is generally positioned opposite an arcuate or curved portion  40  of sidewall  28 . However, the present invention contemplates portion  40  of sidewall  28  being flat or non-curved, as well. Further, pump  24  includes a fuel inlet tube  42  disposed proximate to receptacle bottom  34 . Inlet tube  42  includes an inlet aperture  44  that receives fuel to be pumped to the vehicle&#39;s engine. Generally, a filter  46  is disposed over inlet tube  42  and inlet aperture  44  to prevent debris from entering fuel pump  24 .  
         [0019]    In operation, an impeller (not shown) within pump  24  spins at high rotational speeds (i.e., 3000 to 9000 rpm) and produces an acoustical wave which emanates from inlet aperture  44 . The acoustical wave propagates through the fuel contained within receptacle  26 . When the acoustical wave impinges on sidewall portion  40 , fuel delivery module  14  starts to vibrate. The vibration of the fuel delivery module causes fuel tank  12  to vibrate and radiate a sound wave. The sound wave traveling through the fuel tank  12  may be more or less noticeable to a vehicle occupant at various engine and vehicle operating conditions, such as at engine idle or during high speed vehicle operation. For example, at engine idle especially, the sound wave may be quite noticeable and become an annoyance to vehicle occupants. Thus, the present invention provides a system and method for eliminating or reducing radiated noise whose source is an acoustical wave at the inlet aperture  44  of pump  24 .  
         [0020]    Referring now to FIGS. 3 and 4, a plan view and cross-sectional view of receptacle  26  and pump  24  are illustrated, in accordance with the present invention. In a method of the present invention, noise cancellation is provided by maintaining a predetermined distance between inlet aperture  44  of inlet tube  42  and sidewall portion  40 . The predefined distance between inlet aperture  44  and sidewall portion  40  is referenced by dimension A in FIG. 4. The present invention contemplates modifying distance A by either shortening or lengthening inlet tube  42  thereby moving inlet aperture  44  closer or farther away from sidewall portion  40  or by moving sidewall portion  40  closer or farther away from inlet aperture  44 . Preferably, dimension A is approximately equal to a 1/4 of the wavelength of an acoustical wave generated by the impeller of pump  24  that has been identified as causing a noise problem within the vehicle compartment. Further, in a preferred embodiment sidewall portion  40  is curved and inlet aperture  44  is positioned at the center of a circle that defines the curvature of sidewall portion  40 .  
         [0021]    In yet another embodiment of the present invention, shown in FIG. 5, sidewall portion  40  is substituted with a semi-spherical shaped sidewall  48  for focusing pressure pulses, generated by sound waves emanating from the impeller of pump  24 , back toward inlet aperture  44  more efficiently. In order to achieve noise cancellation of the acoustic wave generated by the pump&#39;s impeller, inlet aperture  44  would preferably be located, approximately, a 1/4 of the wavelength of the acoustical wave from semi-spherical shaped sidewall  48  and positioned at the center of a sphere that defines the semi-spherical sidewall  48 .  
         [0022]    Finally, the method of the present invention provides a receptacle depth, referenced by dimension C in FIG. 4, of a 1/4 of the wavelength of the acoustical wave in question or alternatively at least not set to half the wavelength of the acoustical wave. Further, other dimensions of receptacle  26  such as dimension B which is the distance between opposing sidewalls  28  and sidewall portion  40  should be so dimensioned to prevent the formation of standing waves, therefore dimensions B should not be near 1/2 the wavelength of the acoustical wave or any integer multiple thereof. Of course, to achieve all of the dimensional limitations stated above for dimensions A, B, and C, receptacle  26  would preferably not be perfectly cylindrical. In other words, opposing sidewalls  28  would not join to form a cylinder. However, a cylindrical receptacle  26  may be used as long as dimensions A and C were held and the inlet aperture  44  was not disposed in the center of a circle that defines the curvature of the cylinder&#39;s sidewalls. Thus, the method of the present invention provides noise cancellation by placing the source of the acoustical wave at a predefined distance from a reflective opposing sidewall.  
         [0023]    Curved sidewall portion  40  may be integrally molded into receptacle  28  or fixedly secured within receptacle  26  at a predefined distance from sidewall  28 . Further, the present invention contemplates changing the distance between inlet aperture  44  and opposing sidewall portion  40  by replacing inlet tube  42  with a longer or shorter tube  42  to arrive at the desired distance from opposing sidewall portion  40 . Thus, existing receptacles  26  and pump assemblies  24  may be easily modified without significant design changes and cost.  
         [0024]    Referring now to FIG. 6, an alternate embodiment of receptacle  26  is illustrated. The alternate receptacle, referenced by numeral  50 , provides a device and a method for avoiding resonances that amplify noise transmitted to the vehicle passenger compartment. This method and device would be used if the previously described cancellation method was not feasible to employ. In opposition to the method for providing noise cancellation, a de-tuning method of the present embodiment provides a non-uniform wall portion  52  opposite inlet aperture  44  to avoid focusing and reflecting the sound wave emanating from inlet  44  back to the source. Preferably, non-uniform wall portion  52  is corrugated to disperse or scatter the sound wave impinging on wall portion  52 . Further, the inlet aperture  44  should not be positioned at the center of the receptacle or the center of an arc of the opposing sidewall if the sidewall is curved again, to avoid focusing the reflected acoustic wave back to inlet aperture  44 . Further, the various dimensions B, C, D, as shown in FIG. 4, of receptacle  26  should be closer to a 1/4 of the wavelength of the acoustic wave at engine idle rather than to 1/2 the wavelength of the noise generated by the pump&#39;s impeller to avoid amplification of the noise due to vertical standing waves. Further, preferably bottom surface  54  of receptacle  50  should also be corrugated to disperse or scatter sound waves impinging thereon and to avoid the formation of vertical standing waves.  
         [0025]    Thus, the present invention has many advantages and benefits of the prior art. For example, the present invention provides a system and method for canceling acoustic waves which create noise in vehicle engine compartments. Further, other systems and methods of the present invention reduce or eliminate noise amplification without increasing cost or complexity of the system.  
         [0026]    As any person skilled in the art of fuel delivery systems and in methods for reducing or eliminating noise generated by the fuel pump will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of this invention defined in the following claims.