Patent Publication Number: US-6655909-B2

Title: High flow fuel pump

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention generally relates to an automotive fuel pump for use with an automobile engine. 
     BACKGROUND OF THE INVENTION 
     The regenerative fuel pump with a ring impeller is well known in the industry especially for lower voltage, high pressure applications. However, this type of fuel pump has disadvantages when used in higher flow, hot fuel applications. For proper performance, it is desirable that the pump supply only liquid fuel to the fuel injectors of the automobile. Ring impeller pumps when used in high flow, hot fuel applications tend to generate fuel vapors due to the high turbulence of the high pressure flow. When the fuel is hot, the fuel will more easily transform into vapor, thereby compounding the vapor problem. 
     Traditional pumps, such as those described in U.S. Pat. Nos. 5,024,578 and 5,336,045 have attempted to resolve this problem by increasing the width of the flow channel within the fuel pump, expanding the flow channel outward radially. This does not solve all the concerns however, because the flow channel cannot extend outward beyond the radius of the ring impeller. Additionally, the &#39;045 patent and the &#39;578 patent also describe a flow channel with increased depth. This flow channel profile is only useful for relatively lower flow rates of about 100 liters per hour. The wider and deeper flow channel concepts do not solve the vapor concerns in a high flow ring impeller application. Therefore, there is a need for an improved ring impeller fuel pump suitable for high flow and hot fuel handling situations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side sectional view of a fuel pump of the present invention; 
     FIG. 2 is a perspective view of a cover of the present invention; 
     FIG. 3 is a top view of the cover showing a first side of the cover; 
     FIG. 4 is a bottom view of the cover showing a second side of the cover; and 
     FIG. 5 is a sectional view of a portion of FIG. 4 indicated by line  5 — 5  of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description of the preferred embodiment of the invention is not intended to limit the scope of the invention to this preferred embodiment, but rather to enable any person skilled in the art to make and use the invention. 
     Referring to FIG. 1, an embodiment of the pump of the present invention is shown generally at  10 . The pump  10  includes a pump housing  12  for containing the internal components of the pump  10 . A motor  14  is mounted within the pump housing  12 . The motor  14  includes a shaft  16  extending therefrom and is adapted to rotate the shaft  16 . Preferably, the motor  14  is an electric motor. A ring impeller  18  is fixedly attached to the shaft  16  such that the ring impeller  18  rotates with the shaft  16 . 
     A bottom  20  is mounted within the housing  12 . The bottom  20  includes an outlet (not shown) which is in fluid communication with a motor chamber  22  surrounding the motor  14 . The bottom  20  includes an opening  24  to allow the shaft  16  to extend therethrough. The ring impeller  18  is attached to a distal end of the shaft  16  such that the bottom  20  is disposed between the ring impeller  18  and the motor  14 . 
     A cover  26  is mounted on an end of the housing  12  and is attached to the bottom  20 . The ring impeller  18  is enclosed between the cover  26  and the bottom  20  within a pumping chamber  28  defined by the cover  26  and the bottom  20 . The outlet of the bottom  20  allows fuel to flow from the pumping chamber  28  to the motor chamber  22 . Referring to FIGS. 2 through 4, the cover includes a first side  30  and a second side  32 . The first side  30  has a fuel inlet orifice  34  which is in fluid communication with the pumping chamber  22  to allow fuel to flow into the pumping chamber  22 . The second side  32  of the cover  26  defines a sealing surface that is adapted for sealed engagement with the bottom  20 . 
     A flow channel  36  is formed within the second side  32  of the cover  26 . The flow channel  36  forms one side of the pumping chamber  22 . The inlet orifice  34  allows fuel to enter the fuel pump  10  into the flow channel  36 . The flow channel  36  includes four discrete sections. A first section defines an inlet  38 , a second section defines a ramp  40 , a third section defines a ramp end  42  and a fourth section defines a main channel  44 . 
     Referring to FIG. 5, the inlet  38  has a smooth curved profile. The curved profile has a radius  46  that is preferably at least 2 millimeters. Preferably, the radius  46  of the curved profile is between about 3 millimeters and about 4 millimeters. 
     The ramp  40  extends from the inlet  38  at an angle  48  relative to the second side  32  and connects the inlet  38  to the ramp end  42 . The ramp end  42  extends from the ramp  40  at an angle  50  relative to the second side  32  and connects the ramp  40  to the main channel  44 . The angle  48  of the ramp  40  relative to the second side  32  is less than seven degrees and the angle  50  of the ramp end  42  relative to the second surface  32  is between about 10 degrees and about 20 degrees. Preferably, the angle  48  of the ramp  40  relative to the second surface  32  is about 5 degrees. 
     The total length of the inlet  38 , the ramp  40  and the ramp end  42  is defined by an arc  52  extending from the inlet orifice  34 . The arc  52  extends from the inlet orifice  34  a distance between about 40 degrees and about 90 degrees. Preferably, the arc  52  extends about 70 degrees. The relative lengths of the inlet  38 , the ramp  40  and the ramp end  42  relative to the total length are about 10% inlet  38 , about 70% ramp  40  and about 20% ramp end  42 . 
     The main channel  44  of the cover  26  includes a vapor purge hole  54  extending from the flow channel  36  through the cover  26 . The vapor purge hole  54  allows fluid communication between the flow channel  36  and the first side  30  of the cover  26 . The vapor purge hole  54  is located a distance from the inlet orifice  34  defined by an arc  56  extending between about 90 degrees and about 120 degrees from said inlet orifice  34 . Preferably, the arc  56  extends about 110 degrees. The diameter of the vapor purge hole  54  is between about 1 millimeter and about 2 millimeters. Preferably, the diameter of the vapor purge hole  54  is about 1.25 millimeters. 
     Referring again to FIG. 3, the first side of the cover  26  also includes an energy dissipation channel  58  in fluid communication with the vapor purge hole  54 . The energy dissipation channel  58  includes a plurality of dissipation dams  60  adapted to dissipate the energy of the purged flow and at least one opening  62  adapted to guide the purged fuel for smooth flowing out with lower noise. A more detailed description of the vapor purge hole  54  and the energy dissipation channel  58  appears in U.S. Pat. No. 5,330,319 which is assigned to the assignee of the present application and is hereby incorporated by reference into the present application. 
     Referring again to FIG. 5, the flow channel  36  includes a junction  64  where the inlet  38  and the ramp  40  meet. The junction  64  is located at a depth  65  from the second side  32  of the cover  26  of between about 3 millimeters and about 6 millimeters. Preferably, the junction  64  is located at a depth of about 5 millimeters from the second side  32  of the cover  26 . 
     The flow channel  36  has a width which is defined by an outer wall  66  and an inner wall  68 . The diameter  70  of the outer wall  66  is the same as the outer diameter of the vanes on the ring impeller  18 . The diameter  72  of the inner wall  68  is less than about 1.5 millimeters smaller than the diameter of the vanes roots on the ring impeller  18 . Preferably, the diameter  72  of the inner wall  68  is about 1 millimeter less than the diameter of the vane roots on the ring impeller  18 . 
     The foregoing discussion discloses and describes one preferred embodiment of the invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that changes and modifications can be made to the invention without departing from the true spirit and fair scope of the invention as defined in the following claims. The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.