Automotive fuel pump impeller with staggered vanes

The present invention generally relates to automotive fuel pumps, and more particularly to a regenerative turbine type rotary impeller.

Regenerative fuel pumps that have an impeller with a ring extending around the outer diameter have been widely used in automotive applications because of their robust manufacturing, low cost, and high efficiency. These features are emphasized in low voltage, high pressure applications. However, this impeller design exhibits “disadvantageous” characteristics when used in an Electrical Returnless Fuel System (ERFS). When the vehicle is at idle, the fuel pump of an ERFS typically spins at approximately 3,000 to 4,000 revolutions per minute (rpm), while the fuel pump of a traditional system spins at approximately 8,000-9,000 rpm. At the lower rpm rate, the impeller exhibits pressure pulsation noise in the fuel pump.

Therefore, there is a need for a fuel pump having an impeller which dampens the pressure pulsation within the fuel pump while maintaining the efficiency advantages of the ring impeller.

FIG. 1 is a sectional view of a fuel pump of the present invention;

FIG. 2 is a perspective view of first preferred embodiment of an impeller from the fuel pump shown in FIG. 1;

FIG. 2 a is an enlarged portion of FIG. 2;

FIG. 3 is side view of the impeller shown in FIG. 2;

FIG. 4 is a side view similar to FIG. 3 of a second preferred embodiment of the impeller;

FIG. 4 a is a side view similar to FIG. 4 wherein all of the vanes have the same radial height; and

FIG. 5 is an exploded view of the pump body, impeller and pump cover of the fuel pump shown in FIG. 1 .

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, a fuel pump of the present invention is generally shown at 10 . The fuel pump 10 includes a housing 12 and a motor 14 mounted within the housing 12 . Preferably, the motor 14 is an electric motor with a shaft 18 extending therefrom. An impeller 20 is fitted onto the shaft 18 and is encased within the pump housing 12 between a pump body 22 and a pump cover 24 . The impeller 20 fits onto the shaft 18 such that the impeller 20 is free to move axially along the shaft 18 and rotates with the shaft 18 . Therefore, the impeller 20 “floats” between the pump cover 24 and the pump body 22 . The fuel pump is of a conventional type which is further described in U.S. Pat. Nos. 6,210,102; 6,296,439; and 6,299,406, which are all commonly assigned to the same assignee as the present application and are hereby incorporated by reference into the present application.

The impeller 20 has a central axis which is coincident with the axis of the shaft 18 . The shaft 18 passes through a shaft opening 26 in the pump body 22 , through the impeller 20 , into a cover recess 28 , and abuts a thrust button 30 . The shaft 18 is journalled within a bearing 32 . A pumping chamber 36 is formed along the periphery of the impeller 20 by an annular cover channel 38 of the pump cover 24 and an annular body channel 40 of the pump body 22 . The pump body 22 has a fuel outlet (not shown) leading from the pumping chamber 36 . Pressurized fuel is discharged through the fuel outlet 34 to and cools the motor 14 while passing over the motor 14 to a pump outlet 42 at an end of the pump 10 which is axially opposite a fuel inlet 44 .

Referring to FIG. 2 the impeller 20 has an impeller body 46 which is substantially disk shaped. The impeller body 46 includes a plurality of vanes 50 extending radially outward from an outer circumference 52 of the impeller. Preferably, the number of vanes 50 is a prime number, and the vanes 50 are un-evenly spaced around the outer circumference 52 of the impeller 20 . In other words, the distance between any two adjacent vanes 50 is not a constant, and varies in a non-repeating pattern about the circumference of the impeller 20 . By having a prime number of vanes 50 and spacing them un-evenly, harmonic pulsations are reduced within the impeller 20 . Further, the pattern of the spacing of the vanes 50 is a non-repeating pattern to further reduce harmonic pulsations.

Referring to FIG. 2 a , each vane 50 includes a first half 54 and a second half 56 . The first half 54 extends outward radially from the outer circumference 52 adjacent a first face 58 of the impeller 20 , and the second half 56 extends outward radially from the outer circumference 52 adjacent a second face 60 of the impeller 20 . The second half 56 of each of the vanes 50 is shifted rotationally relative to the first half 54 . Preferably, the second half 56 of each vane is shifted approximately half the distance between the first half 54 of that vane 50 and the first half 54 of the next adjacent vane 50 . Said differently, each second half 56 is spaced half way between two adjacent first halves 54 .

Preferably, each of the vanes 50 includes a radially outwardly extending connector wall 66 . The connector wall 66 extends radially from the outer circumference 52 of the impeller body 46 and extends circumferentially between the first and second halves 54 , 56 of the vane 50 . The radial height of the connector wall 66 is the same as the radial height of the first and second halves 54 , 56 between which the connector wall 66 extends.

Referring to FIG. 3, the vanes 50 can be divided into two different groups of first vanes 62 and second vanes 64 . First vanes 62 have a first radial height, and second vanes 64 have a second radial height. Preferably, the radial height of the second vanes 64 are approximately two-thirds the height of the first vanes 62 . The first and second halves 54 , 56 of any single vane 50 preferably have the same radial height.

The first and second vanes 62 , 64 are spaced and intermingled with one another about the outer circumference 52 of the impeller body 46 . Similar to the spacing of the vanes 50 , the pattern of the intermingled first and second vanes 62 , 64 is preferably a non-repeating pattern. Additionally, preferably the number of first vanes 62 , having the first radial height, is a prime number.

Referring to FIG. 4, a second preferred embodiment of the impeller includes a ring portion 76 around the outer circumference 52 connected to the vanes 50 . In the second preferred embodiment, the first radial height is such that the first vanes 62 extend fully outward from the outer circumference 52 of the impeller body 46 and connect to the outer ring portion 76 . The second radial height is less than the first radial height, such that the second vanes 64 of the second group extend outward from the outer circumference 52 of the impeller body 46 and do not extend fully out to connect with the outer ring 76 .

The impeller 20 , with the outer ring portion 76 , can include first and second vanes 50 as shown in FIG. 4, or alternatively, the impeller 20 , having the outer ring portion 76 , can include only vanes 50 which extend radially outward and connect with the outer ring portion 76 , as shown in FIG. 4 a.

Referring to FIG. 5, the pump body 22 includes a stripper area 68 . The body channel 40 of the pump body 22 includes a channel inlet 41 , and extends annularly from the channel inlet 41 around the pump body 22 to the fuel outlet 34 . The stripper area 68 is defined as the area between the channel inlet 41 of the body channel 40 and the fuel outlet 34 extending annularly from the channel inlet 41 of the body channel 40 away from the body channel 40 to the fuel outlet 34 . Preferably, the circumferential distance between any two adjacent vanes 50 of the first radial height is less than one-half the circumferential width of the stripper area 68 . If the distance between two adjacent vanes 50 of the first radial height is more than one-half of the circumferential width of the stripper area 68 , then leakage can occur between the channel inlet 41 of the body channel 40 and the fuel outlet 34 .

The impeller 20 is preferably injection molded from a plastic material, such as phenolic, acetyl, PPS, or other plastics. It is to be understood that the impeller 20 could also be made from non-plastic materials known to those skilled in the art such as aluminum or steel. The fuel pump 10 can be mounted within a fuel tank (not shown) or, alternatively, can be mounted in-line between the fuel tank and the engine of the vehicle.

The foregoing discussion discloses and describes two preferred embodiments 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 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.