Abstract:
A fuel pump for a vehicle includes a pump section having a flow channel and a rotatable impeller cooperating with said flow channel to pump fuel therethrough. The fuel pump also includes a motor section disposed adjacent the pump section and having a motor to rotate the impeller. The fuel pump further includes an outlet section disposed adjacent the motor section to allow pumped fuel to exit the fuel pump. The pump section includes a mechanism for minimizing leakage of fuel from the flow channel radially.

Description:
TECHNICAL FIELD 
     The present invention relates generally to fuel pumps and, more particularly, to a fuel pump of a vehicle. 
     BACKGROUND OF THE INVENTION 
     It is known to provide a fuel tank in a vehicle to hold fuel to be used by an engine of the vehicle. It is also known to provide a fuel pump to pump fuel from the fuel tank to the engine. One type of fuel pump is known as a high-pressure turbine fuel pump. The high-pressure turbine fuel pump typically includes an impeller rotatable between inlet and outlet plates. The impeller is of a closed vane type to improve pump efficiency and performance. The impeller has a hub portion, a plurality of blade tips extending radially from the hub portion and disposed circumferentially thereabout and a peripheral ring portion extending radially from the blade tips. However, the closed vane impeller is hampered by flow loss due to wear of a peripheral ring portion that shrouds the blade tips of the impeller. 
     The peripheral ring that shrouds the blade tips of the closed vane impeller improves pump performance by providing a rotational surface that aids to direct the fluid into a flow channel. The peripheral ring also functions as an axial sealing surface between the fluid pressure within the flow channel and the fluid pressure surrounding a major diameter of the impeller. When the fuel pump is operated in fuel containing concentration of abrasive contaminants, the peripheral ring can wear and result in a loss of flow. 
     Therefore, it is desirable to minimize the flow loss associated with axial wear of the peripheral ring portion of the impeller while maintaining performance benefits the peripheral ring portion provides in a fuel pump for a vehicle. It is also desirable to provide a fuel pump for a fuel tank in a vehicle that eliminates higher cost and process infeasible materials such as ceramic plates and impeller. It is further desirable to improve fuel pump durability using existing low cost materials and production feasible methods for a fuel pump for a fuel tank in a vehicle. 
     SUMMARY OF THE INVENTION 
     It is, therefore, one object of the present invention to provide a fuel pump for a fuel tank in a vehicle which eliminates a sealing function of a peripheral ring portion of an impeller. 
     It is another object of the present invention to provide a fuel pump for a vehicle that minimizes flow loss associated with axial wear of a peripheral ring portion of an impeller. 
     To achieve the foregoing objects, the present invention is a fuel pump for a vehicle including a pump section having a flow channel and a rotatable impeller cooperating with the flow channel to pump fuel therethrough. The fuel pump also includes a motor section disposed adjacent the pump section and having a motor to rotate the impeller. The fuel pump further includes an outlet section disposed adjacent the motor section to allow pumped fuel to exit the fuel pump. The pump section includes a mechanism for minimizing leakage of fuel from the flow channel radially. 
     One advantage of the present invention is that a new fuel pump is provided for a vehicle. Another advantage of the present invention is that the fuel pump uses existing low cost materials and production feasible methods. Yet another advantage of the present invention is that the fuel pump has improved fuel pump durability due to elimination of a dynamic sealing surface. Still another advantage of the present invention is that the fuel pump has improved fuel pump efficiency due to reduced friction at the impeller outside diameter surface. 
     Other objects, features, and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary elevational view of a fuel pump, according to the present invention. 
     FIG. 2 is a sectional view taken along line  2 — 2  of FIG.  1 . 
     FIG. 3 is a fragmentary elevational view of a pump section of the fuel pump of FIG.  1 . 
     FIG. 4 is an elevational view of a portion of an impeller of the pump section of FIG.  3 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings and in particular FIGS. 1 and 2, one embodiment of a fuel pump  12 , according to the present invention, is shown for a vehicle (not shown). The fuel pump  12  includes a pump section  14  at one axial end, a motor section  16  adjacent the pump section  14  and an outlet section  18  adjacent the motor section  16  at the other axial end. As known in the art, fuel enters the pump section  14 , which is rotated by the motor section  16 , and is pumped past the motor section  16  to the outlet section  18 . The outlet section  18  has an outlet member  20  extending axially with a passageway  22  extending axially therethrough. The outlet member  20  also has a plurality of projections or barbs  24  extending radially outwardly for attachment to a conduit (not shown). The outlet member  20  also includes a check valve  26  disposed in the passageway  22 . It should be appreciated that the fuel flowing to the outlet section  18  flows into the outlet member  20  and through the passageway  22  and check valve  26  when open to the conduit. It should also be appreciated that, except for the pump section  14 , the fuel pump  12  is conventional and known in the art. 
     Referring to FIGS. 1 through 4, the pump section  14  includes an impeller  28  mounted to a rotatable shaft  30  of a motor  32  of the motor section  16  for rotation therewith. The impeller  28  is generally planar and circular in shape. The impeller  28  has a hub portion  34  attached to the shaft  30  by suitable means (not shown). The impeller  28  has an interior web portion  36  surrounding the hub portion  34 . The impeller  28  also has a plurality of blades  38  extending radially from the interior web portion  36  and disposed circumferentially thereabout. The blades  38  have blade tips  40  extending axially and circumferentially forming a generally “V” shaped. The impeller  28  has a peripheral ring portion  42  extending radially from the blades  38  to shroud the blade tips  40 . The peripheral ring portion  42  has an axial shroud height less than an axial blade height of the blade tips  40 . The impeller  28  is made of a rigid material such as plastic. It should be appreciated that the small blades or serrations (not shown) can be added to the outside diameter of the peripheral ring portion  42  to prevent the potential for counter flow of fluid. It should also be appreciated that the blade tips  40  are shrouded by the peripheral ring portion  42  that forms the desired flow shaping geometry, but does not extend for the full height of the blades  38 , thereby allowing the corners of the blade tips  40  to impart a momentum to the fluid contained in a flow channel  54  to be described and eliminates the potential of counter flow within eddy currents formed by the fluid flow exiting the peripheral ring portion  42 . 
     The pump section  14  also includes an inlet plate  44  disposed axially on one side of the impeller  28  and an outlet plate  46  disposed axially on the other side of the impeller  28 . The inlet plate  44  and outlet plate  46  are generally planar and circular in shape. The inlet plate  44  and outlet plate  46  are enclosed by a housing  48  and fixed thereto. The inlet plate  44  and outlet plate  46  have an inlet or first recess  50  and an outlet or second recess  52 , respectively, located axially opposite the blade tips  40  adjacent to the peripheral ring portion  42  to form a flow channel  54  for a function to be described. The recesses  50  and  52  are annular and allow fuel to flow therethrough from an inlet port  56  (FIG. 2) to an outlet port  58  of the pump section  14 . It should be appreciated that the impeller  28  rotates relative to the inlet plate  44  and outlet plate  46  and the inlet and outlet plates  44  and  46  are stationary. 
     The pump section  14  also includes a spacer ring  60  disposed axially between the inlet plate  44  and outlet plate  46  and spaced radially from the impeller  28  to form a gap  62  therebetween. The spacer ring  60  is fixed to the housing  38  and is stationary relative to the impeller  28 . The spacer ring  60  is generally planar and circular in shape. The spacer ring  60  has an inner diameter  64  that is of equal value to the outside diameter of the flow channel  54 . The outer diameter of the peripheral ring portion  42  is in close radial proximity to the inner diameter  64  of the spacer ring  60 . The gap  62  between the outer diameter of the impeller  28  and the inner diameter  64  of the spacer ring  60  is maintained at a distance adequate to prevent annular counter flow while maintaining clearance for rotation of the impeller  28 . The spacer ring  60  may have a stripper radius portion  66  extending radially and circumferentially into the gap  62  that forms a reduced cross-sectional area or flow stripper between the inlet and outlet ports  56  and  58 . It should be appreciated that fluid flows into the inlet recess  50  and through the flow channel  54  and out the outlet recess  52  as indicated by flow velocity vectors  68 . 
     In operation of the fuel pump  12 , the motor  32  rotates the shaft  30 , which in turn, rotates the impeller  28  as indicated by the arrow  70 . The fluid velocity created at the rotating surface of the outside diameter or surface of the peripheral ring portion  42  of the impeller  28  coupled with the viscous force gradient within the fluid cause the fluid such as fuel to flow. The corners of the blade tips  40  impart a momentum to the fluid contained in the flow channel  54 . The fuel flows from the inlet port  56  through the flow channel  54  to the outlet port  58  without the potential of counter flow within the eddy current formed by the fluid flow exiting the peripheral ring portion  42 . It should be appreciated that this configuration eliminates outer diameter sealing surface wear by using the static spacer ring  60  as the axial seal, while maintaining the flow shaping geometry benefits of a rotating outer diameter peripheral ring portion  42  of the impeller  28 . It should also be appreciated that frictional torque losses are reduced, eliminating the surface contact associated with the rotational sealing function. It should further be appreciated that pump durability is improved by shifting the axial outer diameter sealing function from the rotating peripheral ring portion  42  of the impeller  28  to the static outer diameter spacer ring  60  while maintaining the rotational flow direction benefits and performance benefits of the peripheral ring portion  42 . 
     The present invention has been described in an illustrative manner. 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. 
     Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.