Patent Publication Number: US-6984099-B2

Title: Fuel pump impeller

Description:
FIELD OF THE INVENTION 
     The claimed invention relates to a fuel pump impeller. In particular, the invention concerns a ring impeller for use with a fuel pump. 
     BACKGROUND OF THE INVENTION 
     Regenerative fuel pumps have been used for years in automotive fuel supply applications. Conventional 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 the periphery of a central hub. Rotation of the impeller draws fuel into a pumping chamber located within the pump housing. The pumping action of the impeller causes fuel to exit the fuel pump housing at high pressure. Regenerative fuel pumps are commonly used in automotive applications because they produce a more constant discharge pressure than other types of pumps. They also typically cost less and generate less audible noise during operation than other known pumps. 
     Pump efficiency and noise are two characteristics that are considered important when designing a fuel pump impeller. Staggered vane impellers have been used to provide lower pressure pulsation and noise, at the sacrifice of pump efficiency. Staggered vane impellers utilize a first row of vanes on the cover side of the impeller and a second row of vanes on the body side of the impeller. The first row of vanes are staggered relative to the second row of vanes. Partition or connecting walls may be utilized between staggered vanes. 
     SUMMARY 
     According to one embodiment of the invention, an impeller includes a central hub, a first plurality of vanes, a second plurality of vanes, a plurality of partition walls, and a plurality of ribs. The first plurality of vanes extend radially from the central hub in a first row. The second plurality of vanes extend radially from the central hub in a second row positioned adjacent to and staggered from the first row. Each of the vanes from the first row is paired with a vane from the second row to form a plurality of pairs of vanes. Each partition wall is positioned between the vanes in the pair of vanes. The plurality of ribs extend radially from the central hub around the circumference of the hub. The ribs are positioned between each of the vane pairs in alignment with the partition walls and have a rib thickness. Each of the partition walls have a bottom thickness and the bottom thickness of the partition walls are equal to the rib thickness. A ring impeller may further include an outer ring coupled to the first and second rows of vanes. A regenerative fuel pump according to this embodiment includes the impeller discussed above, a pump housing having an inlet and an outlet, a motor, and a shaft coupled between the motor and the impeller for driving the impeller to pump fuel from the inlet to the outlet of the housing. 
     In another embodiment, an impeller includes a central hub, a first plurality of vanes, a second plurality of vanes, and a plurality of partition walls. The first plurality of vanes extend radially from the central hub in a first row. The second plurality of vanes extend radially from the central hub in a second row positioned adjacent to and staggered from the first row. Each of the vanes from the first row is paired with a vane from the second row to form a plurality of vane pairs, with each of the vane pairs having a first row vane and a second row vane. Each partition wall is positioned between each first and second row vane within the pair of vanes. And each partition wall has a forward edge and a rear edge. A first reduced material area is provided on the forward edge of each partition wall where the first row vane meets the partition wall. A second reduced material area is provided on the rear edge of each partition wall where the second row vane meets the partition wall. A ring impeller further includes an outer ring coupled to the first and second rows of vanes. A regenerative fuel pump according to this embodiment includes the impeller discussed above, a pump housing having an inlet and an outlet, a motor, and a shaft coupled between the motor and the impeller for driving the impeller to pump fuel from the inlet to the outlet of the housing. 
     In yet another embodiment, an impeller includes a central hub, a first plurality of vanes, a second plurality of vanes, and a plurality of partition walls. The first plurality of vanes extend radially outwardly from the central hub in a first row. The second plurality of vanes extend radially outwardly from the central hub in a second row and are positioned adjacent to and staggered from the first row. Each of the vanes from the first row is paired with a vane from the second row to form a plurality of pairs of vanes. Each partition wall is positioned between the vanes in each pair of vanes. The vanes in the first row of vanes are unevenly spaced in a non-repeating pattern and vanes in the second row of vanes are spaced equidistantly between the vanes of the first row of vanes. A ring impeller further includes an outer ring coupled to the first and second rows of vanes. A regenerative fuel pump according to this embodiment includes the impeller discussed above, a pump housing having an inlet and an outlet, a motor, and a shaft coupled between the motor and the impeller for driving the impeller to pump fuel from the inlet to the outlet of the housing. 
     In a further embodiment, an impeller includes a central hub, a first plurality of vanes, a second plurality of vanes, and a plurality of partition walls. The first plurality of vanes extend radially from the central hub in a first row. The second plurality of vanes extend radially from the central hub in a second row positioned adjacent to and staggered from the first row. Each of the vanes from the first row is paired with a vane from the second row to form a plurality of pairs of vanes. Each partition wall is positioned between the vanes of each pair of vanes. The vanes in the first row are unevenly spaced and have a spacing of the vanes that ranges from about 70% to 140% of a spacing equal to an even spacing, with the even spacing being the spacing that would occur if the vanes were evenly spaced around the central hub. A ring impeller further includes an outer ring coupled to the first and second rows of vanes. A regenerative fuel pump according to this embodiment includes the impeller discussed above, a pump housing having an inlet and an outlet, a motor, and a shaft coupled between the motor and the impeller for driving the impeller to pump fuel from the inlet to the outlet of the housing. 
     In another embodiment, an impeller includes a central hub, a first plurality of vanes, a second plurality of vanes, and a plurality of partition walls. The first plurality of vanes extend radially outwardly from the central hub in a first row. The second plurality of vanes extend radially outwardly from the central hub in a second row positioned adjacent to and staggered from the first row. Each of the vanes from the first row is paired with a vane from the second row to form a plurality of pairs of vanes, with vanes in each pair of vanes having the same height. Each partition wall is positioned between the vanes of the pair of vanes. Some of the vanes in the first row have a first height and some of the vanes in the first row have a height that is less than the first height. A ring impeller further includes an outer ring coupled to the first and second rows of vanes. A regenerative fuel pump according to this embodiment includes the impeller discussed above, a pump housing having an inlet and an outlet, a motor, and a shaft coupled between the motor and the impeller for driving the impeller to pump fuel from the inlet to the outlet of the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         FIG. 1  is a cross-sectional view of a prior art regenerative fuel pump; 
         FIG. 2  is a perspective view of a first embodiment of the cover side of a ring impeller according to the invention; 
         FIG. 3  is plan view of the cover side of the ring impeller shown in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the ring impeller of  FIG. 3 , taken at line  4 — 4 ; 
         FIG. 5  is a plan view of the body side of the ring impeller shown in FIG.  2 . 
         FIG. 6  is a cross-sectional view of the ring impeller of  FIG. 5 , taken at line  6 — 6 ; 
         FIG. 7  is a cross-sectional view of the ring impeller of  FIG. 5 , taken at line  7 — 7 ; 
         FIG. 8  is an enlarged cross-sectional view of  FIG. 7 , taken at encircled area  8 — 8 ; 
         FIG. 9  is a plan view of the cover side of one embodiment of a ring impeller according to the invention; 
         FIG. 10  is a plan view of the body side of the ring impeller shown in  FIG. 9 ; and 
         FIG. 11  is a perspective view of an alternative embodiment of the cover side of a ring impeller according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a prior art regenerative fuel pump  10 . The pump  10  is surrounded by a housing  12  having an inlet  14  and an outlet  16  for pumping fuel into the pump  10  from a fuel tank (not shown) and out of the pump  10  to the engine of an automotive (not shown). The housing  12  houses a motor  18 , an impeller  20 , and a shaft  22  coupled between the motor  18  and the impeller  20  for driving the impeller  20 . The motor  18  is preferably an electric motor, but other types of motors may also be utilized. The shaft  22  is journaled within a bearing  24 . The impeller  20  is encased between a pump body  26  and a pump cover  28 . The inlet side of the impeller  20  is the cover side  30 , and the outlet side of the impeller  20  is the body side  32 . The pump cover  28  has a flow channel  34  for receiving fuel from the inlet  14 . The pump body  26  has a flow channel  36  for receiving fuel from the impeller  20 . Fuel is drawn into the pump inlet  14  by the impeller  20  from a fuel tank (not shown) or other source. Fuel exits the impeller  20  through the body and flows around the motor to cool the motor  18  before it is discharged through the pump outlet  16  under high pressure. 
     According to the present invention, an improved impeller  20  is provided for use in a regenerative fuel pump  10 , such as that shown in FIG.  1 . One embodiment of the impeller  20  is shown in  FIGS. 2-9 . The impeller  20  has a plurality of vanes that extend radially outwardly from a central hub  38  and terminate at an outer ring  40 . The vanes are spaced around the entire circumference of the central hub  38 . The central hub  38  is an annular disc that has a shaft opening  42  through which the shaft  22  (shown in  FIG. 1 ) passes to rotate the impeller  20  around the shaft opening  42 . The impeller  20  includes pressure balance holes  44  that extend axially through the impeller  20 . The pressure balance holes  44  are utilized to keep the impeller  20  centered and balanced within the pump housing  12  upon the introduction of fuel into the housing inlet  14 . 
     Referring to  FIGS. 3-8 , the impeller cover side  30  and body side  32  are shown. The cover side  30 , shown in  FIG. 3 , faces the pump cover  28  and the body side  32 , shown in  FIG. 5 , faces the pump body  26 . The impeller  20  includes two rows of vanes  48  that extend radially outwardly from the peripheral surface  46  of the central hub  38 , as shown best in  FIGS. 6 and 7 . A first row of vanes  50  is positioned on the cover side  30  of the impeller  20  and a second row of vanes  52  is positioned adjacent the first row of vanes  50 , but on the body side  32  of the impeller  20 . In a preferred embodiment, the first and second rows of vanes  50 ,  52  have a combined width that extends across the entire width W1 of the central hub&#39;s peripheral surface  46 . 
     The second row of vanes  52  is staggered relative to the first row of vanes  50 . Staggering is utilized to obtain a desired sound quality. The vanes  48  preferably have a chevron configuration, such that the first row of vanes  50  extend from the cover side  30  at an angle α other than 90 degrees, as shown in  FIGS. 6 and 7 . The second row of vanes  52  then extend from the body side  32  at a corresponding angle α other than 90 degrees. As shown in  FIGS. 6 and 7 , the angle α is less than 90 degrees in the direction of rotation R. In a preferred embodiment, angle α is about 66°±2°. The combination of the first and second rows of vanes  50 ,  52  form the chevron-shaped configuration. 
     The first row of vanes  50  are unevenly spaced about the periphery of the central hub  38 . They may also be spaced in a non-repeating pattern. The second row of vanes  52  are staggered relative to the vanes in the first row  50  and may also be unevenly spaced in a non-repeating pattern. The number of vanes  48  in the first and second rows is preferably equal, and is a prime number of vanes. For example, 37, 43, or 47 vanes may be provided in each row, among other prime numbers of vanes. The number of vanes  48  will be in part dependent on the size of the central hub  38 . 
     In a preferred embodiment, the first row of vanes  50  are spaced at about 70% to about 140% of an even spacing if the vanes were evenly spaced about the periphery of the hub  38 . In another embodiment, the spacing is about 70% to about 130% of an even spacing. Other spacings may also be utilized provided they result in random, uneven spacing and a balanced impeller  20 . 
     In determining the spacing of the vanes  48 , it is first necessary to determine the even spacing, which can be calculated by dividing the number of vanes by 360°: 
         Even   ⁢           ⁢   spacing     =       Number   ⁢           ⁢   of   ⁢           ⁢   Vanes       360   ⁢   °           
 
The result of the above calculation is multiplied by the desired range, such as, 70% to 130%.
 
Lower Range of Spacing=Even spacing×70%
 
Upper Range of Spacing=Even spacing×130%
 
The spacing of the vanes in the first row  50  is then randomly determined, keeping in mind the upper and lower ranges calculated above. In determining the spacing, it is also preferred that the vanes  48  be balanced around the central hub  38 .
 
     The spacing for the second row of vanes  52  may be determined using the above formulas, as long as the second row  52  is staggered relative to the first row of vanes  50  and the vanes remain balanced around the central hub  38 . In another, preferred embodiment, the vanes  48  in the second row  52  are spaced mid-way between the vanes in the first row  50 . By positioning the vanes in the second row  52  mid-way between the vanes in the first row  50 , the vanes in the second row  52  will be unevenly spaced. In addition, if the vanes in the first row  50  are positioned in a non-repeating pattern, the vanes in the second row will also be spaced in a non-repeating pattern using the mid-way spacing. As shown in  FIG. 7 , each second row  52  vane is preferably spaced mid-way between the trailing edge  54  of the forward vane and the leading edge  56  of the rearward vane in the first row of vanes  50 . 
     Each of the vanes  48  in the first row of vanes  50  are paired with a vane  48  in the second row of vanes  52  to form pairs of vanes  60 . It is preferred that each vane  48  in the first row  50  be paired with a vane  48  in the second row  52  that is adjacent and behind each vane in the first row  50 . A partition wall  62  joins each of the vanes in the pair  60 . In a preferred embodiment, each of the vanes in the pair  60  and the partition wall  62  all have the same height H 1 , which extends to and joins with the outer ring  40  of the impeller  20 . In an alternative embodiment, the vanes in each pair  60  and the partition wall  62  may have a height H 2  that is shorter than the distance from the peripheral surface  46  of the central hub  38  to the outer ring  40 , as will be discussed in greater detail below. 
     Each of the vanes  48  in the first row of vanes  50  has a chamfered or curved surface  64  on the trailing edge  54  at the cover side  30  of the vanes  48 . In one embodiment, the angle of the curved or chamfered surface  64  is about 25°±2° relative to the direction of rotation R. Each of the vanes  48  in the second row of vanes  52  has a chamfered or curved surface  66  at the trailing edge  68  at the body side  32  of the vanes  48 . In one embodiment, the angle of the curved or chamfered surface  66  on each vane in the second row  52  is about 23°±2° relative to the direction of rotation R of the impeller  20 . The angle of the chamfer for the first and second row vanes may be the same or may be different for each row of vanes. 
     The vanes of the first and second rows  50 ,  52  preferably have a similar profile. As shown in  FIG. 3 , the vanes  48  have a bottom portion  70  that extends at about a 90° angle relative to the peripheral surface  46  of the central hub  38 . At approximately half the height H 1  of the vanes  48 , the vanes  48  curve forward to form a generally convex shape in the direction of rotation R of the impeller  20 . The shape shown resembles an airfoil shape. Other shapes may also be utilized. 
     A central rib  72  extends radially outwardly from the central hub  38  between each of the adjacent pairs  60  of vanes, as shown in  FIGS. 3 and 4 . The central rib  72  has a height H 3  that is less than the height of the adjacent vanes  48  and partition walls  62 . The length L of each central rib is equal to the length of the vane groove, which is the axially extending opening  74  between each adjacent pair  60  of vanes. The use of a central rib  72  helps to lower noise and raise impeller efficiency. 
     In a preferred embodiment, the central rib  72  has a cross-section that is V-shaped, or generally V-shaped. The rib  72  may alternatively have a ¼ circle or wedge shape. Other shapes may also be utilized. The partition walls  62  are an extension of the central rib  72  such that the combination of the central rib  72  and partition walls  62  form a continuous wall around the centerline of the central hub  38 . 
     As shown best in  FIG. 8 , the forward edge  76  and rear edge  78  of the partition wall  62  each include an area  80  where material is removed from the edges  76 ,  78  in order to reduce the sharpness of the corner between the vanes  48  and the partition wall  62 . Softening of the corner helps to reduce the likelihood of cavitation problems. In particular, the area  80  of the partition wall  62  that is removed may be a rounded edge, a chamfer, or a notch, among other surface treatments. The length of the area  80  that is removed may extend from the top of the partition wall  62  to the top of the central rib  72 , or may extend part of the distance from the top of the partition wall  62  to the top of the central rib  72 . The width W 2  of the material removed is preferably equal to half of the partition wall  62  width although other widths may also be desirable. In one embodiment, the chamfer at the forward edge  76  of the partition wall  62  is formed at an angle β of 45°±0.5° relative to the direction of rotation R and the chamfer at the rearward edge  78  of the partition wall  62  is formed at an angle θ of 45°±0.5° relative to the direction of rotation R. The angles β and θ may be the same, or may be different. 
     An example of an impeller  20  having 43 vanes in each row that incorporates uneven, non-repeating spacing, as discussed above, is shown in  FIGS. 9 and 10 .  FIG. 9  shows the spacing for the first row of vanes  50  on the cover side  30  and  FIG. 10  shows the spacing for the second row of vanes  52  on the body side  32  of the same impeller. In determining the spacing, a 70% to 140% range was utilized according to the following calculations: 
         Even   ⁢           ⁢   spacing     =         Number   ⁢           ⁢   of   ⁢           ⁢   Vanes       360   ⁢   °       =       43     360   ⁢   °       =     8.4   ⁢   °             
 Lower Range of Spacing=Even spacing×70%=8.4°×70%=5.9°
 
Upper Range of Spacing=Even spacing×140%=8.4°×140%=11.6°
 
Thus, in an embodiment utilizing  43  vanes in the first and second rows  50 ,  52  with an uneven spacing of 70% to 140% of even spacing, a spacing ranging from 5.9° to 11.6° is preferred.
 
       FIG. 11  shows an alternative embodiment of the ring impeller  90  according to the invention. The ring impeller  90  utilizes the same spacing as discussed above, but also utilizes shortened vanes  92  in combination with full length vanes  94 . The full length vanes  94 , like those discussed above in connection with  FIGS. 1-10 , extend from the outer periphery of the central hub  38  to the outer ring  40 , but do not touch the outer ring  40  of the impeller  90 . In one embodiment, the shortened vanes  92  are about ⅔ the height H 1  of the full-length vanes  94 . 
     The shortened vanes  92  are preferably randomly spaced between the full-length vanes  94 , and may be provided singly, or in groups. As shown in  FIG. 11 , some of the vane pairs  60  are single shortened vanes while some of the vane pairs include two vane pairs  60  that are positioned side-by-side within the row. The pairs of vanes  60  and accompanying partition walls  62  each preferably have the same height. Thus, where the first vane in the pair  60  is full-length, the second row vane and partition wall within the vane pair are also full length. Where the first row vane is shortened, the second row vane and partition wall within the vane pair  60  are also shortened. In a preferred embodiment, as shown in  FIG. 11 , all the shortened vanes  92  have the same height H 2 , although other embodiments may be provided where the shortened vanes have differing heights. The shape of the shortened vanes  92  is preferably similar or the same as the shape of the full-length vanes. 
     The impeller  20 ,  90  is preferably formed of a plastic material using an injection molding process. Types of materials that may be utilized include phenolics or PPS (thermoplastic), among other types of materials. Material may be injected into a mold on the cover side  30  of the impeller  20 ,  90 . A material recycling code may be provided in a recess  96  formed on the impeller  20 ,  90 , such as on the body side  32  of the impeller  20 ,  90  as shown in FIG.  5 . 
     While the above concepts are discussed in the context of a ring impeller, they may also be utilized in a no-ring impeller. 
     While various features of the claimed invention are presented above, it should be understood that the features may be used singly or in any combination thereof. Therefore, the claimed invention is not to be limited to only the specific embodiments depicted herein. 
     Further, it should be understood that variations and modifications may occur to those skilled in the art to which the claimed invention pertains. The embodiments described herein are exemplary of the claimed invention. The disclosure may enable those skilled in the art to make and use embodiments having alternative elements that likewise correspond to the elements of the invention recited in the claims. The intended scope of the invention may thus include other embodiments that do not differ or that insubstantially differ from the literal language of the claims. The scope of the present invention is accordingly defined as set forth in the appended claims.