U.S. patent application number 14/803394 was filed with the patent office on 2017-01-26 for fluid pump.
The applicant listed for this patent is DELPHI TECHNOLOGIES, INC.. Invention is credited to Mohammed Aslam, John G. Fischer, Daniel Herrera, Partab Jeswani.
Application Number | 20170023022 14/803394 |
Document ID | / |
Family ID | 57837038 |
Filed Date | 2017-01-26 |
United States Patent
Application |
20170023022 |
Kind Code |
A1 |
Herrera; Daniel ; et
al. |
January 26, 2017 |
FLUID PUMP
Abstract
A fluid pump includes an inlet; an outlet; a motor; and an
impeller rotated by the motor about an axis, the impeller being
positioned axially between an inlet plate and an outlet plate. The
inlet plate includes a channel that receives fluid from the inlet,
the channel being defined by an inner wall and an outer wall. The
channel has a first region extending over an angle of at least
150.degree. and a second region extending from the first region
over an angle of 61.8.degree. to 71.8.degree.. The inner wall has a
first radius centered about the axis which is constant over the
first region and the second region. The outer wall has a second
radius centered about the axis which is constant over the first
region and also has a third radius not centered about the axis
which is constant over the second region.
Inventors: |
Herrera; Daniel; (Cd. Juarez
Chihuahua, MX) ; Jeswani; Partab; (Missouri City,
TX) ; Fischer; John G.; (Goodrich, MI) ;
Aslam; Mohammed; (Flint, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DELPHI TECHNOLOGIES, INC. |
TROY |
MI |
US |
|
|
Family ID: |
57837038 |
Appl. No.: |
14/803394 |
Filed: |
July 20, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 13/0693 20130101;
F04D 29/669 20130101; F04D 5/002 20130101; F04D 5/007 20130101;
F04D 29/528 20130101 |
International
Class: |
F04D 29/66 20060101
F04D029/66; F04D 29/52 20060101 F04D029/52; F04D 13/06 20060101
F04D013/06 |
Claims
1. A fluid pump comprising: an inlet which introduces fluid into
said fluid pump; an outlet which discharges fluid from said fluid
pump; a motor within said fluid pump; and a pumping member rotated
by said motor about an axis such that rotation of said pumping
member by said motor pumps fluid from said inlet to said outlet,
said pumping member being positioned axially between an inlet plate
which is stationary and an outlet plate which is stationary; said
inlet plate includes an inlet plate flow channel in an inlet plate
face of said inlet plate that faces toward said pumping member such
that said inlet plate flow channel receives fluid from said inlet,
said inlet plate flow channel being defined by an inner wall and an
outer wall wherein: said inlet plate flow channel has a first
region and a second region, said first region extending over an
angle of at least 150.degree. and said second region extending from
said first region over an angle of 61.8.degree. to 71.8.degree.;
said inner wall has a first radius which is constant over said
first region and said second region, said first radius being
centered about said axis; and said outer wall has a second radius
which is constant over said first region and which is centered
about said axis, said outer wall also has a third radius which is
constant over said second region and which is not centered about
said axis.
2. A fluid pump as in claim 1 wherein said second region of said
inlet plate flow channel has a first end that is proximal to said
first region and a second end which is distal from said first
region and terminates said inlet plate flow channel.
3. A fluid pump as in claim 2 wherein said outer wall converges to
said inner wall at said second end.
4. A fluid pump as in claim 1 wherein said third radius is less
than said second radius.
5. A fluid pump as in claim 1 wherein: said inlet plate flow
channel is further defined by a bottom wall which connects said
inner wall to said outer wall; and said bottom wall tapers over the
entirety of said second region, thereby varying the depth of said
inlet plate flow channel within said second region.
6. A fluid pump as in claim 5 wherein said bottom wall tapers at a
constant rate over the entirety of said second region.
7. A fluid pump as in claim 6 wherein said bottom wall tapers at
said constant rate over the entirety of said second region to said
inlet plate face.
8. A fluid pump as in claim 5 wherein: said bottom wall has an
initial tapered section within said second region such that said
initial tapered section is proximal to said first region; said
bottom wall has a final tapered section within said second region
such that said initial tapered section is between said final
tapered section and said first region; said initial tapered section
tapers at a first constant rate from said first region to said
final tapered section; and said final tapered section tapers at a
second constant rate from said initial tapered section.
9. A fluid pump as in claim 8 wherein: said first constant rate is
greater than said second constant rate.
10. A fluid pump as in claim 9 wherein said final tapered section
tapers from said initial tapered section to said inlet plate
face.
11. A fluid pump as in claim 1 wherein said third radius is
centered about a center point which is laterally offset from said
axis toward said first region.
12. A fluid pump as in claim 11 wherein said center point is offset
from said axis toward said second region in addition to toward said
first region.
13. A fluid pump as in claim 1 wherein: said inlet plate flow
channel has an inlet region at one end of said inlet plate flow
channel such that said first region is between said inlet region
and said second region and such that said inlet opens into said
inlet region; and said second region terminates said inlet plate
flow channel.
Description
TECHNICAL FIELD OF INVENTION
[0001] The present invention relates to a fluid pump; more
particularly to a fuel pump; even more particularly to a fuel pump
with an electric motor which rotates an impeller that is located
axially between an inlet plate and an outlet plate; and still even
more particularly to an inlet plate flow channel of the inlet plate
which minimizes noise due to structural vibrations induced by fluid
hammer at the end of the inlet plate flow channel.
BACKGROUND OF INVENTION
[0002] Fluid pumps, and more particularly fuel pumps for pumping
fuel, for example, from a fuel tank of a motor vehicle to an
internal combustion engine of the motor vehicle, are known. U.S.
Pat. No. 6,824,361 to Yu et al. shows a typical electric fuel pump
which includes and impeller with a plurality of blades that is
located axially between stationary inlet and outlet plates. The
inlet plate includes an inlet which allows fuel to enter the fuel
pump such that the inlet is in fluid communication with an inlet
channel formed in a face of the inlet plate that faces toward the
impeller. The inlet channel is arcuate in shape such that the inlet
opens into a first end of the inlet channel and such that fuel
flows from the first end to a second end of the inlet channel when
the impeller is rotated by an electric motor of the fuel pump. Fuel
that reaches the second end of the inlet channel is pushed through
spaces between the blades of the impeller and into an outlet
channel formed in a face of the outlet plate that faces toward the
impeller. One end of the outlet channel includes an outlet passage
which extends axially through the outlet plate. Consequently, the
fuel that has been pressurized by the impeller passes through the
outlet passage and past the electric motor to an outlet of the fuel
pump. Motion of the blades of the impeller causes fluid pressure
fluctuations which in turn causes vibration of the inlet plate
which propagates through the rest of the structure of the fuel
pump. Furthermore, when the fuel reaches the end of the inlet
channel, a fluid hammer effect may be produced, thereby resulting
in a high frequency noise that may be objectionable. While not
shown in U.S. Pat. No. 6,824,361 to Yu et al., it is known to
decrease the depth of the inlet channel at the end of the inlet
channel such that the inlet channel may decrease in depth at a
first constant rate over a first distance and then taper at a
second constant rate over a second distance such that the first
rate is greater than the second rate.
[0003] What is needed is a fuel pump which minimizes or eliminates
one or more of the shortcomings as set forth above.
SUMMARY OF THE INVENTION
[0004] Briefly described, a fluid pump includes an inlet which
introduces fluid into the fluid pump; an outlet which discharges
fluid from the fluid pump; a motor within the fluid pump; and a
pumping member rotated by the motor about an axis such that
rotation of the pumping member by the motor pumps fluid from the
inlet to the outlet, the pumping member being positioned axially
between an inlet plate which is stationary and an outlet plate
which is stationary. The inlet plate includes an inlet plate flow
channel in an inlet plate face of the inlet plate that faces toward
the pumping member such that the inlet plate flow channel receives
fluid from the inlet, the inlet plate flow channel being defined by
an inner wall and an outer wall. The inlet plate flow channel has a
first region and a second region, the first region extending over
an angle of at least 150.degree. and the second region extending
from the first region over an angle of 61.8.degree. to
71.8.degree.. The inner wall has a first radius which is constant
over the first region and the second region, the first radius being
centered about the axis. The outer wall has a second radius which
is constant over the first region and which is centered about the
axis. The outer wall also has a third radius which is constant over
the second region and which is not centered about the axis. The
arrangement of the second region minimizes the fluid hammer effect
at the end of the inlet channel and also minimizes vibration of the
inlet plate during operation, and consequently, noise generated by
the vibration of the inlet plate is also minimized.
BRIEF DESCRIPTION OF DRAWINGS
[0005] This invention will be further described with reference to
the accompanying drawings in which:
[0006] FIG. 1 is an exploded isometric view of a fuel pump in
accordance with the present invention;
[0007] FIG. 2 is an axial cross-sectional view of the fuel pump in
accordance with the present invention;
[0008] FIG. 3 is an exploded isometric view of a portion of the
fuel pump in accordance with the present invention;
[0009] FIG. 4 is an isometric view of a motor frame of the fuel
pump in accordance with the present invention;
[0010] FIG. 5 is an isometric view of the motor frame of FIG. 4 now
shown in a different orientation;
[0011] FIG. 6 is an axial view of an inlet plate of the fuel pump
in accordance with the present invention;
[0012] FIG. 7 is an unfolded cross-sectional view of the inlet
plate taken through section line 7-7 of FIG. 6;
[0013] FIG. 8 is an axial cross-sectional view of the inlet plate
taken through section line 8-8 of FIG. 6; and
[0014] FIG. 9 is an unfolded cross-sectional view similar to FIG. 7
showing an alternative arrangement.
DETAILED DESCRIPTION OF INVENTION
[0015] Reference will be made to FIGS. 1 and 2 which are an
exploded isometric view and an axial cross-sectional view
respectively of a fluid pump illustrated as fuel pump 10 for
pumping liquid fuel, for example gasoline or diesel fuel, from a
fuel tank (not shown) to an internal combustion engine (not shown).
While the fluid pump is illustrated as fuel pump 10, it should be
understood that the invention is not to be limited to a fuel pump,
but could also be applied to fluid pumps for pumping fluids other
than fuel. Fuel pump 10 generally includes a pump section 12 at one
end, a motor section 14 adjacent to pump section 12, and an outlet
section 16 adjacent to motor section 14 at the end of fuel pump 10
opposite pump section 12. A housing 18 of fuel pump 10 retains pump
section 12, motor section 14 and outlet section 16 together. Fuel
enters fuel pump 10 at pump section 12, a portion of which is
rotated by motor section 14 as will be described in more detail
later, and is pumped past motor section 14 to outlet section 16
where the fuel exits fuel pump 10.
[0016] Motor section 14 includes an electric motor 20 which is
disposed within housing 18. Electric motor 20 includes a shaft 22
extending therefrom into pump section 12. Shaft 22 rotates about an
axis 24 when an electric current is applied to electric motor 20.
Electric motor 20 will be described in greater detail later.
[0017] With continued reference to FIGS. 1 and 2, pump section 12
includes an inlet plate 26, a pumping member which is illustrated
as an impeller 28, and an outlet plate 30. Inlet plate 26 is
disposed at the end of pump section 12 that is distal from motor
section 14 while outlet plate 30 is disposed at the end of pump
section 12 that is proximal to motor section 14. Both inlet plate
26 and outlet plate 30 are fixed relative to housing 18 to prevent
relative movement between inlet plate 26 and outlet plate 30 with
respect to housing 18. Outlet plate 30 defines a spacer ring 32 on
the side of outlet plate 30 that faces toward inlet plate 26.
Impeller 28 is disposed axially between inlet plate 26 and outlet
plate 30 such that impeller 28 is radially surrounded by spacer
ring 32. Impeller 28 is fixed to shaft 22 such that impeller 28
rotates with shaft 22 in a one-to-one relationship. Spacer ring 32
is dimensioned to be slightly thicker than the dimension of
impeller 28 in the direction of axis 24, i.e. the dimension of
spacer ring 32 in the direction of axis 24 is greater than the
dimension of impeller 28 in the direction of axis 24. In this way,
inlet plate 26, outlet plate 30, and spacer ring 32 are fixed
within housing 18, for example by crimping the end of housing 18
proximal to outlet plate 30. Axial forces created by the crimping
process will be carried by spacer ring 32, thereby preventing
impeller 28 from being clamped tightly between inlet plate 26 and
outlet plate 30 which would prevent impeller 28 from rotating
freely. Spacer ring 32 is also dimensioned to have an inside
diameter that is larger than the outside diameter of impeller 28 to
allow impeller 28 to rotate freely within spacer ring 32 and
axially between inlet plate 26 and outlet plate 30. While spacer
ring 32 is illustrated as being made as a single piece with outlet
plate 30, it should be understood that spacer ring 32 may
alternatively be made as a separate piece that is captured axially
between outlet plate 30 and inlet plate 26.
[0018] Inlet plate 26 is generally cylindrical in shape, and
includes an inlet 34 that extends through inlet plate 26 in the
same direction as axis 24. Inlet 34 is a passage which introduces
fuel into fuel pump 10. Inlet plate 26 also includes an inlet plate
flow channel 36 formed in an inlet plate face 26a of inlet plate 26
that faces toward impeller 28. Inlet plate flow channel 36 is in
fluid communication with inlet 34. Inlet plate 26 and inlet plate
flow channel 36 will be described in greater detail later.
[0019] Outlet plate 30 is generally cylindrical in shape and
includes an outlet plate outlet passage 40 that extends through
outlet plate 30 in the same direction as axis 24. Outlet plate
outlet passage 40 is in fluid communication with outlet section 16
as will be describe in more detail later. Outlet plate 30 also
includes an outlet plate flow channel 42 formed in the face of
outlet plate 30 that faces toward impeller 28. Outlet plate flow
channel 42 is in fluid communication with outlet plate outlet
passage 40. Outlet plate 30 also includes an outlet plate aperture,
hereinafter referred to as lower bearing 44, extending through
outlet plate 30. Shaft 22 extends through lower bearing 44 in a
close fitting relationship such that shaft 22 is able to rotate
freely within lower bearing 44 such that radial movement of shaft
22 within lower bearing 44 is substantially prevented. In this way,
lower bearing 44 radially supports a lower end 46 of shaft 22 that
is proximal to pump section 12.
[0020] Impeller 28 includes a plurality of blades 48 arranged in a
polar array radially surrounding and centered about axis 24 such
that blades 48 are aligned with inlet plate flow channel 36 and
outlet plate flow channel 42. Blades 48 are each separated from
each other by a blade chamber 49 that passes through impeller 28 in
the general direction of axis 24. Impeller 28 may be made, for
example only, by a plastic injection molding process in which the
preceding features of impeller 28 are integrally molded as a single
piece of plastic.
[0021] Outlet section 16 includes an end cap 50 having an outlet 52
for discharging fuel from fuel pump 10. Outlet 52 may be connected
to, for example only, a conduit (not shown) for supplying fuel to
an internal combustion engine (not shown). Outlet 52 is in fluid
communication with outlet plate outlet passage 40 of outlet plate
30 for receiving fuel that has been pumped by pump section 12.
[0022] With continued reference to FIGS. 1 and 2 and with
additional reference to FIGS. 3 and 4, electric motor 20 includes a
rotor or armature 54 with a plurality of circumferentially spaced
motor windings 56 and a commutator portion 58, a motor frame 60, a
pair of permanent magnets 62, and a flux carrier 64. Each magnet 62
is in the shape of a segment of a hollow cylinder. Motor frame 60
includes a top section 66 that is proximal to outlet section 16, a
plurality of circumferentially spaced legs 68 extending axially
from top section 66 toward pump section 12, and a base section 70
axially spaced apart from top section 66 by legs 68. Top section
66, legs 68, and base section 70 are preferably integrally formed
from a single piece of plastic, for example only, by a plastic
injection molding process.
[0023] Top section 66 of motor frame 60 includes a first electrical
terminal 72 and a second electrical terminal 74 extending therefrom
and protruding through end cap 50. First electrical terminal 72 and
second electrical terminal 74 are arranged to be connected to a
power source (not shown) such that first electrical terminal 72 and
second electrical terminal 74 are opposite in polarity. First
electrical terminal 72 and second electrical terminal 74 may be
disposed within pre-formed openings in top section 66 or first
electrical terminal 72 and second electrical terminal 74 may be
insert molded with top section 66 when motor frame 60 is formed by
a plastic injection molding process. First electrical terminal 72
is in electrical communication with a first carbon brush 76 while
second electrical terminal 74 is in electrical communication with a
second carbon brush 78. First carbon brush 76 is disposed within a
first brush holder 80 that is defined by top section 66 and is
urged into contact with commutator portion 58 of armature 54 by a
first brush spring 82 that is grounded to end cap 50. Second carbon
brush 78 is disposed within a second brush holder 84 defined by top
section 66 and is urged into contact with commutator portion 58 of
armature 54 by a second brush spring 86 that is grounded to end cap
50. First carbon brush 76 and second carbon brush 78 deliver
electrical power to motor windings 56 via commutator portion 58,
thereby rotating armature 54 and shaft 22 about axis 24.
[0024] Top section 66 of motor frame 60 defines an upper bearing 88
therein which radially supports an upper end 90 of shaft 22 that is
proximal to outlet section 16. Shaft 22 is able to rotate freely
within upper bearing 88 such that radial movement of shaft 22
within upper bearing 88 is substantially prevented.
[0025] Legs 68 are preferably equally circumferentially spaced
around top section 66 and base section 70 and define motor frame
openings 92 between legs 68. Motor frame openings 92 extend axially
from top section 66 to base section 70. One magnet 62 is disposed
within each motor frame opening 92. Magnets 62 may be inserted
within respective motor frame openings 92 after motor frame 60 has
been formed. Alternatively, magnets 62 may be insert molted with
motor frame 60 when motor frame 60 is formed by a plastic injection
molding process. In this way, magnets 62 and legs 68 radially
surround armature 54. While two legs 68 and two magnets 62 have
been illustrated, it should be understood that other quantities of
legs 68 and magnets 62 may be used.
[0026] Base section 70 may be annular in shape and connects legs 68
to each other. Base section 70 includes a base section recess 94
extending axially thereinto from the end of base section 70 that
faces away from top section 66. Base section recess 94 is coaxial
with upper bearing 88 and receives outlet plate 30 closely therein
such that radial movement of outlet plate 30 within base section
recess 94 is substantially prevented. Since base section recess 94
is coaxial with upper bearing 88, a coaxial relationship is
maintained between lower bearing 44 and upper bearing 88 by base
section 70. Base section 70 also defines an annular shoulder 96
that faces toward top section 66. Annular shoulder 96 may be
substantially perpendicular to axis 24.
[0027] Flux carrier 64 is made of a ferromagnetic material and may
take the form of a cylindrical tube. Flux carrier 64 closely
radially surrounds legs 68 of motor frame 60 and magnets 62. Flux
carrier 64 may be made, for example only, from a sheet of
ferromagnetic material formed to shape by a rolling process. The
end of flux carrier 64 that is proximal to base section 70 of motor
frame 60 axially abuts annular should 96 of base section 70 while
the end of flux carrier 64 that is proximal to top section 66 of
motor frame 60 axially abuts a portion of end cap 50 that radially
surrounds top section 66 of motor frame 60. In this way, flux
carrier 64 is captured axially between end cap 50 and annular
shoulder 96 of base section 70.
[0028] Since motor frame 60 may be made as a single piece, for
example only, by a plastic injection molding process, upper bearing
88 and base section recess 94 can be made by a single piece of
tooling, thereby allowing a high degree of control over the
relative positions of upper bearing 88 and base section recess 94.
Consequently, lower bearing 44 can more easily be maintained in a
coaxial relationship with upper bearing 88. Similarly, since first
brush holder 80 and second brush holder 84 may be defined by top
section 66, for example only, by an injection molding process,
first brush holder 80, second brush holder 84, and upper bearing 88
may be formed by a single piece of tooling, thereby allowing a high
degree of control over the relative positions of first brush holder
80, second brush holder 84, and upper bearing 88. Consequently,
first brush holder 80 and second brush holder 84 can be easily
maintained parallel to axis 24 which may be important for first
carbon brush 76 and second carbon brush 78 to adequately interface
with commutator portion 58 of armature 54.
[0029] Reference will now be made to FIGS. 6-8 which are
respectively an axial view of inlet plate 26 looking toward inlet
plate face 26a, an unfolded cross-sectional view taken through
section line 7-7 of FIG. 6, and an axial cross-sectional view taken
through section line 8-8 of FIG. 6. The inventors have discovered
geometry of inlet plate flow channel 36 which minimizes fluid
hammer effects and fluid pressure fluctuation within inlet plate
flow channel 36, thereby minimizing vibration of inlet plate 26
which can be propagated through fuel pump 10 and also minimizing
audible noise that results from the vibration of inlet plate 26
propagating through fuel pump 10. Inlet plate flow channel 36 will
be described in greater detail in the paragraphs that follow.
[0030] As shown in FIG. 6, inlet plate flow channel 36 is generally
arcuate in shape and includes an inlet region 98 at one end of
inlet plate flow channel 36, an outlet region 100 at the other end
of inlet plate flow channel 36, and an intermediate region 102
between inlet region 98 and outlet region 100. Inlet plate flow
channel 36 is defined by an inner wall 104, an outer wall 106 which
is located radially outward of inner wall 104, and a bottom wall
108 which joins inner wall 104 and outer wall 106.
[0031] Inlet region 98 extends over approximately 30.degree. of
inlet plate flow channel 36. Inlet 34 extends axially through inlet
plate 26 at inlet region 98; consequently, fluid is introduced into
inlet plate flow channel 36 at inlet region 98 through inlet 34. At
least a portion of bottom wall 108 within inlet region 98 is
oblique to inlet plate face 26a as can best be seen in FIG. 7.
Consequently, bottom wall 108 within inlet region 98 eases the
change in direction of fuel flow from axially through inlet 34 to
laterally through inlet plate flow channel 36.
[0032] Intermediate region 102 extends over the majority of inlet
plate flow channel 36 and extends over at least 150.degree., and
preferably extends about 215.degree. as illustrated herein. Inner
wall 104 within intermediate region 102 is defined by a radius
R.sub.104 where inner wall 104 intersects inlet plate face 26a such
that radius R.sub.104 is constant over intermediate region 102 and
is centered about axis 24. As shown in FIG. 8, inner wall 104 may
be arcuate in cross-section shape across the width of inlet plate
flow channel 36 within intermediate region 102. Similarly, outer
wall 106 within intermediate region 102 is defined by a radius
R.sub.106a where outer wall 106 intersects inlet plate face 26a
such that radius R.sub.106a is constant over intermediate region
102 and is centered about axis 24 and such that radius R.sub.106a
is greater than radius R.sub.104. As shown in FIG. 8, outer wall
106 may be arcuate in cross-section shape across the width of inlet
plate flow channel 36 within intermediate region 102. Intermediate
region 102 may be defined by an intermediate region first section
102a and an intermediate region second section 102b such that
intermediate region first section 102a is located between inlet
region 98 and intermediate region second section 102b. Intermediate
region first section 102a and intermediate region second section
102b are substantially the same except for their respective depths,
i.e. the distance that bottom wall 108 is located axially from
inlet plate face 26a. More specifically, the axial distance from
bottom wall 108 within intermediate region first section 102a to
inlet plate face 26a is greater than the axial distance from bottom
wall 108 within intermediate region second section 102b to inlet
plate face 26a. Consequently, a step 110 is defined by bottom wall
108 at the transition from intermediate region first section 102a
and intermediate region second section 102b.
[0033] Outlet region 100 extends over a range of 61.8.degree. to
71.8.degree. of inlet plate flow channel 36 and is preferably about
66.8.degree.. Inner wall 104 within outlet region 100 is defined by
radius R.sub.104 where inner wall 104 intersects inlet plate face
26a such that radius R.sub.104 is constant over outlet region 100
and is centered about axis 24. Consequently, inner wall 104 is
defined by radius R.sub.104 within intermediate region 102 and
outlet region 100. As shown in FIG. 8, inner wall 104 may be
arcuate in cross-section shape across the width of inlet plate flow
channel 36. Outer wall 106 within outlet region 100 is defined by a
radius R.sub.106b where outer wall 106 intersects inlet plate face
26a such that radius R.sub.106b is constant over outlet region 100.
However, radius R.sub.106b is centered about a center point 112
which is not coincident with axis 24, consequently, radius
R.sub.106b is not centered about axis 24. Radius R.sub.106b is
preferably less than radius R.sub.106a and center point 112 is
preferably offset laterally from axis 24 in a direction that is
toward intermediate region 102 and toward outlet region 100, i.e.
down and to the right as oriented in FIG. 6. In this way, outer
wall 106 converges to inner wall 104 within outlet region 100. It
should be noted that a termination radius 113 may join inner wall
104 and outer wall 106 at the end of outlet region 100 which is
distal from intermediate region 102, i.e. the end of outlet region
100 which terminates inlet plate flow channel 36, such that
termination radius 113 is less than about 15% of radius R.sub.106b
while still considering inner wall 104 to have a constant radius
over outlet region 100 and while still considering outer wall 106
to have a constant radius over outlet region 100 and while still
considering outer wall 106 to converge to inner wall 104. As shown
in FIG. 8, outer wall 106 may be arcuate in cross-section shape
across the width of inlet plate flow channel 36. The depth of inlet
plate flow channel 36, i.e. the distance that bottom wall 108 is
located axially from inlet plate face 26a, preferably decrease over
the entire length of outlet region 100. As shown in FIG. 7, bottom
wall 108 tapers at a constant rate from the end of outlet region
100 that is proximal to intermediate region 102 to the end of
outlet region 100 that is distal from intermediate region 102,
thereby defining a bottom wall tapered section 114. Alternatively,
as shown in FIG. 9, bottom wall tapered section 114 may include an
initial tapered section 114a that is proximal to intermediate
region 102 a final tapered section 114b that is distal from
intermediate region 102 such that initial tapered section 114a
tapers toward inlet plate face 26a at greater rate than final
tapered section 114b. However, initial tapered section 114a and
final tapered section 114b together taper the entire length of
outlet region 100 just like bottom wall tapered section 114 shown
in FIG. 7. It should be noted that both initial tapered section
114a and final tapered section 114b taper at constant rates.
[0034] In operation, inlet 34 is exposed to a volume of fuel (not
shown) which is to be pumped to, for example only, an internal
combustion engine (not shown). An electric current is supplied to
motor windings 56 in order to rotate shaft 22 and impeller 28. As
impeller 28 rotates, fuel is drawn through inlet 34 into inlet
plate flow channel 36. Fuel within inlet plate flow channel 36
flows through inlet region 98, intermediate region 102, and outlet
region 100. Blade chambers 49 allow fuel from inlet plate flow
channel 36 to flow to outlet plate flow channel 42, primarily from
outlet region 100. Impeller 28 subsequently discharges the fuel
through outlet plate outlet passage 40 and consequently through
outlet 52. The inventors have discovered that defining inner wall
104 with radius R.sub.104 over intermediate region 102 and outlet
region 100 together with defining outer wall 106 with radius
R.sub.106a over intermediate region 102 and radius R.sub.106b over
outlet region 100 allows the fuel to be efficiently directed out of
inlet plate flow channel 36, thereby minimizing the interaction
between the fuel and the end of inlet plate flow channel 36 which
would tend to cause vibration of inlet plate 26 that can propagate
through fuel pump 10 and would also tend to cause a fluid hammer
effect. Consequently, vibration of inlet plate 26 is minimized,
thereby also minimizing noise generated by the vibration of inlet
plate 26.
[0035] While this invention has been described in terms of
preferred embodiments thereof, it is not intended to be so limited,
but rather only to the extent set forth in the claims that
follow.
* * * * *