Regenerative fuel pump impeller

Abstract: A semi-open staggered vane impeller for use in an automotive fuel pump. Each vane has a cover-side vane tooth and a body-side vane tooth extending from a central vane groove. Each vane is coupled to the next adjacent vane by a rib that runs substantially parallel to the vane groove. In addition, each vane has a phase difference between its cover-side vane tooth and body-side vane tooth that is a function of the length of the vane groove.

Description: Technical Field The present invention relates to a vehicle fuel pump and more particularly to a regenerative fuel pump impeller for use in an automobile. Background Conventional tank-mounted automotive fuel pumps typically have a rotary-pumping element, such as an impeller that is encased within a pump housing. Typical impellers have a plurality of vanes and ribs formed around their peripheries and rotation of the impellers draw fuel into a pumping chamber located within the pump housing. The rotary pumping action of the impeller vanes and ribs causes fuel to exit the housing at high-pressure. Regenerative fuel pumps are commonly used to pump fuel in automotive engines because they have a more constant discharge pressure than, for example, positive displacement pumps. In addition, regenerative pumps typically cost less and generate less audible noise during operation than other known pumps. EP 0 931 927 describes a non-open vane motor-driven fuel pump. Vanes are provided between an inner hub and an outer rim. Vane grooves are provided between the vanes and are formed to be curvilinear as viewed from a radial cross section. Portions which extend from a forward side of a direction of rotation toward the connections are formed to be curvilinear. Communicatioa holes are formed forwardly or rearwardly of the vane grooves in the direction of rotation to allow communication between the vane grooves on both surfaces. An opening of the vane grooves is formed into various shapes, for example, straight in a radial direction, curved in the direction of rotation, or inclined in the direction of rotation. Pump efficiency and noise are two problems commonly associated with fuel pump technology, and specifically associated with impeller technology. Many solutions have been proposed to improve the pump technology. For example, regenerative open vane (line teeth) impeller fuel pumps have achieved greater pumping efficiency over the prior generation non-open vane fuel pumps such as described in EP 0 931 927. An example of an open vane impeller fuel pump is described in EP 5,123,809. The impeller has a hub with close fins on either side of and having free ends coplanar with the rim of the hub. A fuel in a pump chamber formed between the opposed surfaces of each adjacent pair of close fins is pressurized and forced out by the rotation of the impeller. The delivery pressure of the fuel from the fuel pump is set to a higher level than the pressure in an intake pipe communicating with the engine by about 2 to 3 kg/cm 2 while the flow rate during engine operation is set to a range of 50 to 200 l/h. At least part of the side surface of one of each pair of close fins located on the downstream side is formed parallel to a plane perpendicular to the direction of rotation of the impeller, while an outer end portion of the side surface of the other close fin located on the upstream side is formed so as to be slanted relative to a plane perpendicular to the direction of impeller rotation so that the capacity of the pump chamber is increased, whereby the lowest flow rate in a state where the voltage supplied from the vehicle power source drops when the engine is started is set to 20 l/h or higher, thereby preventing engine starting failure. However, the open vane improvements also generated relatively high vane teeth order pressure pulsation and relatively high noise. In an effort to solve these problems, traditional methods introduced a two-stage pump to create two different phased pressure-pumping actions. These two-stage pumps provided decreased noise and decreased overall pulsation. However, use of these two-stage pumps is complicated and relatively expensive to implement. In another effort to solve the pulsation and noise problem discussed above, a staggered vane impeller pump has also been utilized. An example of a staggered vane impeller pump is described in DE 198 04 680, wherein an impeller hub is provided with a circumferential rib which separates two sets of vanes. The number of vanes on one side is different to that on the other side, and the spacing between the vanes on each side is constant. This is said to reduce noise. While a staggered vane impeller pump provided lower pulsation and noise, it sacrificed pump efficiency, and therefore was not an ideal solution. SUMMARY OF THE INVENTION It is therefore an object of the present invention to introduce a new impeller design that achieves both increased pump efficiency and lower noise. According to a first aspect of the invention there is provided a regenerative pump as specified in claim 1. A second aspect of the invention provides an impeller for use in a rotary machine, as specified in claim 7. A "semi-open staggered vane" impeller for a fuel pump is provided. The fuel pump impeller includes a plurality of vanes that are spaced about and extend radially outward from a central hub of the impeller. Each of the plurality of vanes has a vane body that is coplanar with the top and bottom surfaces of the impeller. Each of the vanes also has a pair of vane teeth extending at an angle from each respective end of the vane body. The vane body also functions to prevent back flow leakage in the impeller. In addition, each of the vanes is connected to the next adjacent vane by a central rib. The length of the vane body (length running coplanar with the impeller) may vary from zero, corresponding to the point where the vane teeth are in phase with respect to each other, to a maximum length equal to the length of the central rib, where the phase difference between the vane teeth are substantially out of phase with respect to each other. The phase difference of the vane teeth affects teeth order pressure pulsation and noise, where the lowest teeth order pressure pulsation and noise is achieved when the length of the vane body is maximized. Other objects and advantages of the present invention will become apparent upon considering the following detailed description and appended claims, and upon reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional side view of a fuel pump having an impeller according to a preferred embodiment of the present invention; Figure 2 is a side elevation view of the cover side of an impeller according to a preferred embodiment of the invention; Figure 3 is an enlarged side view of a portion of the impeller contained within the circle 3 on Figure 2; Figure 4 is a top view of Figure 2 in the direction of the arrow 4; Figure 5 is a side elevation view of the body side of the impeller according to a preferred embodiment of the present invention; Figure 6 is a cross-sectional view of an impeller taken along line 6-6 of Figure 2; Figure 7 is a cross-sectional view of an impeller taken along line 7-7 of Figure 2; Figure 8 is a perspective view of an impeller according to a preferred embodiment of the invention; Figure 9 is a side view of a staggered vane impeller according to the prior art; Figure 10 is a comparison table of flow rate, hydraulic torque, and hydraulic efficiency in a staggered vane type impeller and an impeller according to a preferred embodiment of the present invention; and Figure 11 is a graph illustrative of frequency characteristics for explaining noise-preventing effect of the preferred embodiment versus a baseline impeller. DESCRIPTION OF THE PREFERRED EMBODIMENT(S) Referring now to Figure 1, a cross-sectional view of a fuel pump 20 in accordance with the present invention is illustrated. The fuel pump 20 is preferably for use in a motor vehicle, but may be used in a variety of applications including non-automotive. The fuel pump 20 includes a housing 22 for retaining a motor 24, which is mounted within a motor space 26. The motor 24 is preferably an electric motor, but may be a variety of other motors. The motor 24 has a shaft 28 extending therefrom through a fuel pump outlet 30 and to a fuel inlet 32. The shaft 28 also has a disk-shaped impeller 34 slidingly engaged thereon. The impeller 34 is encased within a pump housing 36, which is comprised of a pump body 38 and a pump cover 40. The impeller 34 includes a central axis 42 that is coincident with the axis of the motor shaft 28. The shaft 28 passes through a shaft opening 44 formed in the center of the impeller 34 and into a recess 46 formed in the pump cover 40. As seen in Figure 1, the shaft 28 is journalled within a bearing 48. The pump body 38 has a flow channel 51 formed therein. The pump cover 40 has a flow channel 50 formed therein. The flow channel 50 leads from a pumping chamber 52A and is located along the periphery of the impeller 34. The flow channel 51 leads from a pumping chamber 52B and is located on the periphery of the impeller and adjacent to the pumping chamber 52A. In operation, fuel is drawn from the fuel tank (not shown), in which a fuel pump 20 may be mounted, through the fuel inlet 32, in the pump cover 40 and into the flow channel 50, 51 by the rotary pumping action of the impeller 34. High-pressure fuel is then discharged through the high-pressure outlet 35 to the motor space 26. The fuel is then passed to the fuel pump outlet 30 and in doing so cools the motor 24. Turning now to Figures 2 through 8, the impeller 100 according to the present invention is shown. The impeller 100 has a plurality of vanes 102 that extend from a central hub 104 and terminate at the impeller periphery. The central hub 104 has a shaft opening 106 through which the shaft (not shown) of the motor (not shown) may pass through to rotate the impeller 100 around its shaft opening 106. The impeller 100 has a plurality of pressure balance holes 140 formed therethrough that function to keep the impeller 100 centered within its housing (not shown) upon the introduction of fuel through the fuel inlet (not shown). The impeller 100 further has a cover side 160, and a body side 170 opposed to one another. The cover side 160 of the impeller 100 has a plurality of ramps 168 for creating a lifting force away from the cover side 160 to balance the weight of the impeller 134 and other potential pressure differences between the two sides of the impeller 100. Each vane 102 of the impeller 100 has a cover-side vane tooth 108 and a body-side vane tooth 110 extending from a respective vane body 112. Each of the cover-side vane teeth 108 has a cover-side point 128 located at a position farthest from the vane body 112 and peripherally terminates at the plane defined by the cover side 160. Each of the body-side vane teeth 110 has a body-side point 130 located at a position farthest from the vane body 112 and peripherally terminates at the plane defined by the body side 170. Each vane 102 is coupled to adjacent vanes 102 through a rib 114. The rib 114 may be of varying height and varying length. However, in the preferred embodiment it is around 60% of the height of the vane body 112. The highest efficiency of pumping action of a preferred embodiment of the present invention is achieved when the height of vane body 112 is equal to the height of the cover-side and body-side vane teeth 108, 110. The length of the central rib 114 may vary as a function of both the length of the vane body 112 and the height of the central rib 114. The length of the central rib 114 can affect noise and impeller efficiency. In a preferred embodiment, the length of the central rib 114 is equal to the length of the vane body 112. Referring now to Figure 8, each vane 102 is uniformly spaced around the periphery of the central hub 104 of the impeller 100. Each cover-side point 128 is similarly spaced equidistant around the periphery of the impeller at a distance 1. Each body-side point 130 is also spaced equidistant around the periphery of the impeller at a distance 2. In addition, each cover-side vane tooth 108 has an angle α1 relative to the vane body 112, and each body-side vane tooth has an angle α2 relative to the vane body 112, such that α1 + α2 is equal to 180 degrees. In addition, there may be a phase difference 3 between a cover-side point 128 and a body-side point 130 located on each vane 102. This phase difference 3 may vary as a function of the length of the vane body 112. When the length of the vane body 112 is 0, the phase difference 3 is 0, which is in phase. As the length of the vane body 112 increases, 3 gets larger, causing the vane teeth 108, 110 to become out of phase with respect to each other. When the vane body 112 reaches its maximum length, where the cover-side point 128 is midway between body-side points 130 on adjacent vanes 102 (or 2/2) and where the body-side point 130 is midway between cover-side points 128 on adjacent vanes 102 (or 1/2), the phase difference 3 is maximized. The preferred embodiment of the present invention as shown in Figure 8 is when the vane body 112 length is maximized. At this point, the impeller 100 has the lowest teeth order pressure pulsation and noise. However, a variety of alternate configurations may be adapted. Another factor that affects pump efficiency is the radial depth of the channel 120. The channel 120 is created between vanes 102 of the impeller 100 and between the rib 114 and the pump housing (shown as 36 in Figure 1). The depth of the channel 120 varies by changing the radial height of the central rib 114 or with the radial height of the vane 102. With the design of the preferred embodiment of the present invention, a deeper channel 120 depth is generally required compared to prior designs, although the depth of the channel 120 will vary according to the pressure of fuel flow through the impeller 100. Referring now to Figure 9, a staggered vane type impeller 900 according to the prior art is depicted. The impeller 900 has a cover-side vane 910 and a body-side vane 920, each has an angle α relative to a central rib 930. Referring now to Figure 10, a tabular representation of the improvements in flow rate, hydraulic torque, and hydraulic efficiency of the preferred embodiment versus a typical staggered vane type impeller as shown in Figure 9 is shown. In Figure 10, flow rates, hydraulic torque, and hydraulic efficiency of the preferred embodiment of the impeller and prior art impeller of Figure 9 were measured at two different pressures/speed settings (200 KPa and 4000 rpm; 284 KPa and 5500 rpm). At the lower setting (200 KPa and 4000 rpm), the flow rate increased from 34.1 to 39.0 LPH, the hydraulic torque decreased form 0.0219 to 0.0212 NM, and the hydraulic efficiency increased from 20.7% to 24.4%. At the higher setting (284 KPa and 5500 rpm), the flow rate increased from 66.6 to 76.3 LPH, the hydraulic torque decreased from 0.0332 to 0.0324 NM, and the hydraulic efficiency increased from 27.5% to 32.3%. Thus, the table indicates that an impeller according to the preferred embodiment shows improvements in flow rate, hydraulic torque, and hydraulic efficiency versus a typical staggered type impeller at both lower and higher pressure/speed settings. Turning now to Figure 11, a graphic representation of noise levels at various frequencies is shown. As the graph indicates, the impeller according to the preferred embodiment shows marked decreases in noise levels compared to a baseline impeller at virtually all speeds from 0 rpm to 5000 rpm. Noises were measured by placing the impellers in a test vehicle. While the invention has been described in terms of preferred embodiments, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings.

Claims: A regenerative pump (20) comprising: a pump housing (36) with a fuel inlet (32) and a fuel outlet (35); and an impeller (100) rotatably mounted within said housing (36), said impeller (100) having a central hub (104) centered on a rotational axis (42) of said impeller (100), said central hub (104) having a plurality of vanes (102) each of which extends radially from said central hub (104) to a free end at the periphery of the impeller (100), each of said plurality of vanes (102) being coupled to said adjacent vane (102) by a rib (114), and wherein each of said plurality of vanes (102) has a vane body (112) having a first height from said hub (104) and a length, a cover-side vane tooth (108) extending from said vane body (112) having a second height from said hub (104), and a body-side vane tooth (110) extending from said vane body (112) having a third height from said hub (104), wherein said cover-side vane tooth (108) and said body-side vane tooth (110) have a phase difference with respect to one another and wherein said vane body (112) runs substantially parallel to said rib (114); each rib (114) co-operating with adjacent vanes (102) and said pump housing (36) to define a channel (120) connecting the fuel inlet (32) and the fuel outlet (35). The regenerative pump (20) of claim 1, wherein said first height of said vane body (112) is equal to said second height of said cover-side vane tooth (108) and is equal to said third height of said body-side vane tooth (110). The regenerative pump (20) of claim 1, wherein said second height of said cover-side vane tooth (108) is equal to said third height of said body-side vane tooth (110). The regenerative pump (20) of claim 1, wherein said phase difference is a function of said length of said vane body (112). The regenerative pump (20) of claim 1, wherein said rib (114) has a fourth height from said hub (104), said fourth height being approximately 60% of said first height of said vane body (112). The regenerative pump (20) of claim 1, wherein said rib (114) has a fourth length and a rib height from said hub (104), said fourth length varying as a function of said first length and said rib height. An impeller (100) for use in a rotary machine comprising: a central hub (104) having a geometric center (42); a plurality of vanes (102) each of which extends radially from said central hub (104) to a free end at the periphery of the impeller (100); each of said plurality of vanes (102) being coupled to said adjacent vane (102) by a rib (114), and wherein each of said plurality of vanes (102) has a vane body (112) having a first height from said hub (104) and a length, a cover-side vane tooth (108) extending from said vane body (112) having a second height from said hub (104), and a body-side vane tooth (110) extending from said vane body (112) having a third height from said hub (104), wherein said cover-side vane tooth (108) and said body-side vane tooth (110) have a phase difference with respect to one another and wherein said vane body (112) runs substantially parallel to said rib (114); each rib (114) having a fourth height from said hub (104) such as to provide an opening between adjacent vanes (102) for fluid to pass from one side of the hub (104) to the other. The impeller (100) of claim 7, wherein said first height of said vane body (112) is equal to said second height of said cover-side vane tooth (108) and said third height of said body-side vane tooth (110). The impeller (100) of claim 7, wherein said second height of said cover-side vane tooth (108) is equal to said third height of said body-side vane tooth (110). The impeller (100) of claim 7, wherein said phase difference is a function of said length of said vane body (112). The impeller (100) of claim 7, wherein said fourth height of said rib (114) is approximately 60% of said first height of said vane body (112). The impeller (100) of claim 7, wherein said rib (114) has a fourth length and a rib height from said hub (104), said fourth length varying as a function of said first length and said rib height.

Inventors: VERKLEEREN RONALD LUCE, YU DEQUAN, VERKLEEREN, RONALD LUCE, YU, DEQUAN
Applicants: VISTEON GLOBAL TECH INC, VISTEON GLOBAL TECHNOLOGIES, INC.
Application year: 2001
Main classification: F04D29
IPC codes: F04D7, F04D29, F04D23, F04D5