U.S. patent application number 16/451409 was filed with the patent office on 2020-12-31 for gerotor-type oil pump.
The applicant listed for this patent is Brose Fahrzeugteile GmbH & Co. Kommanditgesellschaft, Wurzburg. Invention is credited to Karl KRUG, Lyle WARD.
Application Number | 20200408117 16/451409 |
Document ID | / |
Family ID | 1000004183037 |
Filed Date | 2020-12-31 |
United States Patent
Application |
20200408117 |
Kind Code |
A1 |
WARD; Lyle ; et al. |
December 31, 2020 |
GEROTOR-TYPE OIL PUMP
Abstract
An oil pump includes a housing defining a pump cavity having an
inner circumferential wall with a first segment located in a
low-pressure side of the pump cavity. The first segment defines a
recessed cutout. A gerotor pump set is disposed in the cavity and
includes an inner drive rotor and an outer driven annulus. An outer
circumferential wall of the outer annulus and the cutout cooperate
to form an increased radial clearance to reduce friction losses
between the outer annulus and the housing.
Inventors: |
WARD; Lyle; (Royal Oak,
MI) ; KRUG; Karl; (Clawson, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Brose Fahrzeugteile GmbH & Co. Kommanditgesellschaft,
Wurzburg |
Wurzburg |
|
DE |
|
|
Family ID: |
1000004183037 |
Appl. No.: |
16/451409 |
Filed: |
June 25, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01M 2001/0284 20130101;
F01M 1/04 20130101; F01M 2001/0292 20130101; F01M 1/16 20130101;
F01M 2001/0238 20130101 |
International
Class: |
F01M 1/04 20060101
F01M001/04; F01M 1/16 20060101 F01M001/16 |
Claims
1. An oil pump comprising: a housing defining a pump cavity having
an inner circumferential wall with a first segment located in a
low-pressure side of the pump cavity, the first segment defining a
recessed cutout; and a gerotor pump set disposed in the cavity and
including an inner drive rotor and an outer driven annulus, wherein
an outer circumferential wall of the outer annulus and the cutout
cooperate to form an increased radial clearance to reduce friction
losses between the outer annulus and the housing.
2. The oil pump of claim 1, wherein the first segment further
defines a second recessed cutout circumferentially spaced from the
cutout.
3. The oil pump of claim 2, wherein the first segment defines a
bumper between the cutout and the second cutout.
4. The oil pump of claim 1, wherein the recessed cutout has a depth
of at least 0.2 millimeters.
5. The oil pump of claim 1, wherein the inner circumferential wall
defines an inner surface, and recessed cutout has a first surface
extending radially outboard from the inner surface, a back surface
extending circumferentially from the first surface, and a second
surface extending radially inboard from the back surface to the
inner surface.
6. The oil pump of claim 1, wherein the pump cavity further has a
face defining a recessed outlet shadow port having a first portion
radially inboard of a root circle of the inner drive rotor.
7. The oil pump of claim 6, wherein the outlet shadow port further
has a second portion radially outboard of the root circle.
8. The oil pump of claim 7, wherein the first portion is recessed
shallower than the second portion.
9. The oil pump of claim 1 further comprising a cover attached to
the housing to seal the pump cavity, the cover defining a recessed
port located radially inboard of a root circle of the inner drive
rotor.
10. An oil pump comprising: a housing defining a face and an inner
circumferential wall cooperating with the face to define a pump
cavity having a high-pressure side and a low-pressure side, wherein
the circumferential wall defines a recessed cutout extending
arcuately along a portion of the circumferential wall in the
low-pressure side; a gerotor pump set disposed in the cavity and
including: an outer driven annulus defining internal lobes and an
outer circumferential wall circumscribed by the inner
circumferential wall, and an inner drive rotor eccentrically
received within the outer annulus and defining external lobes
cooperating with the internal lobes to define a plurality of fluid
chambers; and a driveshaft extending through the face and coupled
to the inner drive rotor, the driveshaft being configured to rotate
the gerotor pump set within the cavity such that the outer annulus
rotates relative to the inner circumferential wall, wherein the
cutout forms an increased radial clearance between the inner and
outer circumferential walls to reduce friction losses when the
outer annulus rotates relative to the housing.
11. The oil pump of claim 10, wherein the circumferential wall
further defines a second recessed cutout extending arcuately along
another portion of the circumferential wall that is
circumferentially spaced from the cutout and is in the low-pressure
side.
12. The oil pump of claim 11, wherein the circumferential wall
between the cutout and the second cutout forms a bumper.
13. The oil pump of claim 10 further comprising a cover defining an
inlet port and an outlet port, wherein a portion of the inlet port
or the outlet port is disposed radially inboard of a root circle of
the inner drive rotor.
14. The oil pump of claim 10 further comprising a cover defining an
outlet port, wherein a portion of the outlet port is disposed
radially inboard of a root circle of the inner drive rotor.
15. The oil pump of claim 10 further comprising a cover having a
face disposed over the pump cavity and defining a recessed portion
at least partially disposed radially inboard of a root circle of
the inner drive rotor.
16. The oil pump of claim 10 further comprising an electric machine
operably coupled to the driveshaft.
17. An oil pump comprising: a housing defining a pump cavity; a
gerotor pump set disposed in the cavity and including an inner
drive rotor and an outer driven annulus; and a cover including a
front face disposed over the pump cavity, the front face defining
an inlet port and an outlet port, wherein a portion of the outlet
port is radially inboard of a root circle of the inner drive
rotor.
18. The oil pump of claim 17, wherein the portion is a shallow
portion of the outlet port, and the outlet port further has a main
portion, and wherein the main portion has an axially extending wall
and the shallow portion has a bottom wall extending radially from
the axially extending wall.
19. The oil pump of claim 18, wherein housing defines a back face
of the pump cavity, the back face defining inlet and outlet shadow
ports that are opposite the inlet and outlet ports, respectively,
wherein a portion of the outlet shadow port is radially inboard of
the root circle of the inner drive rotor.
20. The oil pump of claim 19, wherein the portion of the outlet
shadow port is a shallow portion, and the outlet shadow port
further has a deeper portion that is radially outboard of the root
circle of the inner drive rotor.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to oil pumps and more
specifically to gerotor-type oil pumps.
BACKGROUND
[0002] A typical vehicle may include one or more oil pumps for
circulating oil through the engine and/or the automatic
transmission. Typically, the engine includes a dedicated oil pump
and the transmission includes a dedicated oil pump. The oil pumps
may be mechanically driven by a crankshaft of the engine. More
recently, electric oil pumps have been introduced to operate the
transmission when the engine is OFF.
[0003] A gerotor-type oil pump may be used for the engine or the
transmission. This type of oil pump is a positive-displacement pump
that includes a pair of internal and external gears disposed within
a pump chamber. The internal gear is eccentrically mounted within
the external gear. The internal gear is rotationally coupled to a
driveshaft powered mechanically or electrically. Rotation of the
inner gear causes the outer gear to rotate in the same direction.
As the inner and outer gears rotate, chambers defined between lobes
of the gears increase and decrease in size forcing oil through the
pump.
SUMMARY
[0004] According to one embodiment, an oil pump includes a housing
defining a pump cavity having an inner circumferential wall with a
first segment located in a low-pressure side of the pump cavity.
The first segment defines a recessed cutout. A gerotor pump set is
disposed in the cavity and includes an inner drive rotor and an
outer driven annulus. An outer circumferential wall of the outer
annulus and the cutout cooperate to form an increased radial
clearance to reduce friction losses between the outer annulus and
the housing.
[0005] According to another embodiment, an oil pump includes a
housing defining a face and an inner circumferential wall
cooperating with the face to define a pump cavity having a
high-pressure side and a low-pressure side. The circumferential
wall defines a recessed cutout extending arcuately along a portion
of the circumferential wall in the low-pressure side. A gerotor
pump set is disposed in the cavity and includes an outer driven
annulus defining internal lobes and an outer circumferential wall
circumscribed by the inner circumferential wall. The gerotor pump
set further includes an inner drive rotor eccentrically received
within the outer annulus and defining external lobes cooperating
with the internal lobes to define a plurality of fluid chambers. A
driveshaft extends through the face and is coupled to the inner
drive rotor. The driveshaft is configured to rotate the gerotor
pump set within the cavity such that the outer annulus rotates
relative to the inner circumferential wall. The cutout forms an
increased radial clearance between the inner and outer
circumferential walls to reduce friction losses when the outer
annulus rotates relative to the housing.
[0006] According to yet another embodiment, an oil pump includes a
housing defining a pump cavity and a gerotor pump set disposed in
the cavity. The gerotor pump set has an inner drive rotor and an
outer driven annulus. A pump cover has a front face disposed over
the pump cavity. The front face defines an inlet port and an outlet
port. A portion of the outlet port is radially inboard of a root
circle of the inner drive rotor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is an axial cross-sectional view of a gerotor-type
oil pump.
[0008] FIG. 2 is a front view of the oil pump with the cover
removed for illustrative purposes.
[0009] FIG. 3 is a perspective view of the cover of the oil
pump.
[0010] FIG. 4 is a perspective view of the pump housing of the oil
pump.
[0011] FIG. 5 is front view of the oil pump with the gerotor pump
set shown in hidden lines for illustrative purposes.
DETAILED DESCRIPTION
[0012] Embodiments of the present disclosure are described herein.
It is to be understood, however, that the disclosed embodiments are
merely examples and other embodiments can take various and
alternative forms. The figures are not necessarily to scale; some
features could be exaggerated or minimized to show details of
particular components. Therefore, specific structural and
functional details disclosed herein are not to be interpreted as
limiting, but merely as a representative basis for teaching one
skilled in the art to variously employ the embodiments. As those of
ordinary skill in the art will understand, various features
illustrated and described with reference to any one of the figures
can be combined with features illustrated in one or more other
figures to produce embodiments that are not explicitly illustrated
or described. The combinations of features illustrated provide
representative embodiments for typical applications. Various
combinations and modifications of the features consistent with the
teachings of this disclosure, however, could be desired for
particular applications or implementations.
[0013] Referring to FIGS. 1 and 2, an oil pump 20 includes a
housing 22. The pump housing 22 defines a cylindrical pump cavity
26 having a back face 28 and an inner circumferential wall 30
extending axially from the back face 28. A gerotor pump set 32 is
disposed within the pump cavity 26 and is configured to circulate
oil. The set 32 includes an inner drive rotor 34 and an outer
driven annulus 36. The rotor 34 is eccentrically supported within
the annulus 36 and defines external lobes 38 cooperating with
internal lobes 40 of the annulus 36 to define a plurality of fluid
chambers 42. The volume of the fluid chambers 42 varies depending
upon the amount of meshing between the lobes 38, 40. This variation
in volumes creates pumping action as will explain in more detail
below.
[0014] A cover 44 is attached to the housing 22 to seal the pump
cavity 26. The cover 44 may be attached to the housing 22 with
fasteners or the like. The cover 44 may include a front face 46
disposed over the pump cavity 26 and the gerotor pump set 32. In
the illustrated embodiment, the inlet and outlet ports 48 and 50
are defined in the cover 44. The inlet and outlet ports 48, 50
extend through the front face 46 to be in fluid communication with
the pump cavity 26. The cover 44 may include connection features
for attaching external fluid conduits to the inlet and outlet ports
48, 50.
[0015] The oil pump 20 may be driven mechanically, such as by an
engine, or electrically, such as by an electric motor. The
illustrated oil pump 20 is an electric pump powered by an electric
actuator, e.g., motor 60, disposed within a motor cavity 62 of the
housing 22. A driveshaft 64 of the motor 60 extends axially through
the back face 28 and into the pump cavity 26. The rotor 34 is
rotationally fixed to the driveshaft 64 such as by a spline
connection. The pump 20 is operated by rotating the rotor 34, such
as in the counterclockwise direction shown in FIG. 2. The spinning
rotor 34 drives the annulus 36 in the same direction as the rotor
34 due to meshing of the lobes 38 and 40. As the rotor 34 and the
annulus 36 rotate relative to each other in the pump cavity 26, oil
is drawn into the chambers 42 as the chamber size increases and is
expelled through the outlet port 50 as the chamber size
decreases.
[0016] Referring to FIGS. 3 and 4, the cover 44 defines
kidney-shaped inlet and outlet ports 48, 50, and the back face 28
defines recessed kidney-shaped inlet and outlet shadow ports 66 and
68. The profiles of the shadow ports 66 and 68 on the back face 28
typically mirror the profiles of the inlet and outlet ports 48 and
50. The kidneys serve as a portion of the inlet and outlet ports
and provide fluid paths from the inlet to the pump cavity and from
the pump cavity to discharge.
[0017] Referring back to FIG. 2, an oil film is formed between the
inner circumferential wall 30 of the pump body 26 and an outer
circumferential wall 70 of the annulus 36. The oil film creates a
fluid bearing for the annulus 36 during operation of the pump 20.
This oil film, however, also creates friction losses due to the
effect of the fluid's viscosity acting on the rotating annulus 36.
The magnitude of the friction loss is a function of the clearance
(radially distance) between the inner and outer circumferential
walls 30, 70. Increasing the clearance reduces the magnitude of the
friction loss. While increasing the clearance may reduce friction
loss, excessive clearance results in unsatisfactory pump
performance. The inner and outer circumferential walls 30, 70 may
be concentric, and the outer circumferential wall 30 is responsible
for maintaining the concentricity of the annulus 36. Excessive
clearance between the circumferential walls 30, 70 may result in
excessive wobble of the annulus 36. As such, a typical clearance
range is between 0.020 and 0.200 millimeters (mm).
[0018] The pump cavity 26 can generally be divided into a
high-pressure side 72 and a low-pressure side 74. The dividing line
75 extends through the center of the annulus 36 and through the
center of the rotor 34. The low-pressure side 74 includes the inlet
port 48 and the inlet shadow port 66, and the high-pressure side 72
includes the outlet port 50 and the outlet shadow port 68.
[0019] During operation of the pump 20, the annulus 36 is driven
towards the segment 76 of the inner circumferential wall 30 located
on the high-pressure side 72 and is driven away from the segment 78
of the inner circumferential wall 30 located on the low-pressure
side 74. The segment 76 acts as a thrust surface that supports the
annulus 36 in place whereas the segment 78 is typically unloaded.
Since the segment 78 is not acting as a thrust surface, the
clearance between the segment 78 and the annulus 36 can be
increased to reduce friction loss of the pump 20 without losing
concentricity of the annulus 36.
[0020] Referring to FIGS. 2 and 4, one or more cutouts 80 are
recessed into the segment 78 to increase the clearance between the
inner circumferential wall 30 and the outer circumferential wall
70. The cutout(s) 80 may be recessed between 0.2 and 2.0 mm. In the
illustrated embodiment, a pair of cutouts 82 and 84 are defined
into the segment 78. The cutouts 82 and 84 may be circumferentially
spaced apart from each other to form a bumper 87 on the
low-pressure side 74. The bumper 87 provides a safeguard to prevent
the annulus 36 from losing concentricity due to a disturbance in
the system. The bumper 87 is an optional feature.
[0021] The inner circumferential wall 30 defines an inner surface
86. The cutout 82 may have a first surface 88 extending radially
outboard from the inner surface 86 and a back surface 90 extending
circumferentially from the first surface 88 to a second surface 92.
The second surface 92 may extend radially inboard from the back
surface 90 to the inner surface 86. The cutout 82 may only extend
axially along a portion of the inner circumferential wall 30. In
the illustrated embodiment, the cutout 82 extends partially down
the wall 30 from an end 94 of the pump housing 22 towards the back
face 28. This creates a ledge 96 that is continuous with the inner
surface 86. The ledge 96 provides support to ensure the
concentricity of the annulus 36 is maintained in the event of
disturbances. In other embodiments, the cutout may extend to the
back face 28. The cutout 84 may have a same or similar structure as
the cutout 82, and for brevity, will not be described again. In the
illustrated embodiment, the cutouts 82 and 84 have a same arc
length, height, and depth, but in other embodiments the cutouts 82
and 84 may a have different arc length, height, and/or depth.
[0022] During operation of the pump 20, an oil film is also formed
between the gerotor set 32 and the front and back faces 46, 28 of
the pump cavity 26. These oil films also create friction losses due
to the effect of the fluid's viscosity acting on the rotating rotor
34 and annulus 36. Removing material from the front and back faces
46, 28 reduces the friction losses similar to the cutouts 80. The
faces already have material removed for the inlet and outlet ports
48 and 50 and the inlet and outlet shadow ports 66, 68, but by
enlarging these ports or creating additional ports friction losses
can be further reduced.
[0023] Referring to FIGS. 4 and 5, the inlet shadow port 66 may
include a main portion 100 and a friction-reducing portion 102. The
main portion 100 is similar to a traditional shadow port whereas
the friction reducing portion 102 is an additional cutout defined
in the back face 28 for the purposes of reducing fluid friction
between the rotor 34 and the back face 28. The main portion 100
includes an inner arcuate edge 104 having a common center with the
rotor 34 and an outer arcuate edge 106 having a common center with
the annulus 36. The arcuate edge 104 has a radius that
substantially matches the root radius of the rotor 34. A root
radius is a radius of the root circle 105 of the rotor 34. A root
circle is a circle that coincides with the bottoms 107 of the lobes
38. Thus, the main portion 100 is disposed radially outboard of the
root circle 105 of the rotor 34.
[0024] The friction-reducing portion 102 is disposed within the
root circle 105 of the rotor 34 to reduce friction between the back
face 28 and the rotor 34. The friction-reducing portion 102
includes an inner arcuate edge 108 having a common center with the
rotor 34. The arcuate edge 104 defines the outer arcuate edge of
the friction-reducing portion 102. The friction-reducing portion
102 may include a vent 110 extending radially inward towards the
driveshaft 64.
[0025] The recess depth of the main portion 100 may be deeper than
the friction-reducing portion 102. For example, the main portion
100 may have a depth between 1.0 and 10.0 mm, and the
friction-reducing portion 102 may have a depth between 0.25 and 2.0
mm. In other embodiments, the depth of the portions 100 and 102 may
be the same. That is, the shadow port 66 may be a single, enlarged
port that has a portion disposed within the root circle 105 of the
rotor 34.
[0026] The outlet shadow port 68 may include a main portion 120 and
a friction-reducing portion 122. The main portion 120 may similar
to a traditional outlet shadow port whereas the friction reducing
portion 122 is an additional cutout defined in the back face 28 for
the purposes of reducing friction between the rotor 34 and the back
face 28. The main portion 120 includes an inner arcuate edge 124
having a common center with the rotor 34 and an outer arcuate edge
126 having a common center with the annulus 38. The arcuate edge
124 has a radius that substantially matches the root radius of the
rotor 34. Thus, the main portion 120 is disposed radially outboard
of the root circle 105 of the rotor 34.
[0027] The friction-reducing portion 122 is disposed within the
root circle 105 of the rotor 34 to reduce friction between the back
face 28 and the rotor 34. The friction-reducing portion 122
includes an inner arcuate edge 128 having a common center with the
rotor 34. The arcuate edge 124 defines the outer arcuate edge of
the friction-reducing portion 122. Like the inlet shadow port 66,
the recess depth of the main portion 120 may be deeper than the
friction-reducing portion 122 or the same depth.
[0028] In the illustrated embodiment, both the inlet shadow port 66
and the outlet shadow port 68 include a friction-reducing portion.
In other embodiments, only one of the inlet and outlet shadow ports
may include a friction reducing portion. In yet another embodiment,
neither of the inlet and outlet shadow ports may include a friction
reducing portion.
[0029] Referring to FIG. 3, the inlet port 48 may include a main
portion 130 and a friction-reducing portion 132. The main portion
130 is similar to a traditional inlet port whereas the friction
reducing portion 132 is an additional cutout defined in the front
face 46 for the purposes of reducing friction between the rotor 34
and the front face 46. The main portion 130 includes an inner
arcuate edge 134 having a common center with the rotor 34 and an
outer arcuate edge 136 having a common center with the annulus 38.
The arcuate edge 134 has a radius that substantially matches the
root radius of the rotor 34. Thus, the main portion 130 is disposed
radially outboard of the root circle 105 of the rotor 34.
[0030] The friction-reducing portion 132 is disposed within the
root circle 105 of the rotor 34. The friction-reducing portion 132
includes an inner arcuate edge 138 having a common center with the
rotor 34. The arcuate edge 134 defines the outer arcuate edge of
the friction-reducing portion 132. The friction-reducing portion
132 may include a vent 140.
[0031] The outlet port 50 may include a main portion 150 and a
friction-reducing portion 152. The main portion 150 may be similar
to a traditional outlet port whereas the friction reducing portion
152 is an additional cutout defined in the front face 46 for the
purposes of reducing friction between the rotor 34 and the front
face 46. The main portion 150 includes an inner arcuate edge 154
having a common center with the rotor 34 and an outer arcuate edge
156 having a common center with the annulus 38. The arcuate edge
154 has a radius that substantially matches the root radius of the
rotor 34. Thus, the main portion 150 is disposed radially outboard
of the root circle 105 of the rotor 34.
[0032] The friction-reducing portion 152 is disposed within the
root circle 105 of the rotor 34. The friction-reducing portion 152
includes an inner arcuate edge 158 having a common center with the
rotor 34. The arcuate edge 154 defines the outer arcuate edge of
the friction-reducing portion 152. In the illustrated embodiment,
both the inlet port 48 and the outlet port 50 include a
friction-reducing portion. In other embodiments, only one of the
inlet and outlet ports 48, 50 includes a friction reducing portion.
In yet another embodiment, neither of the inlet and outlet ports
include a friction reducing portion.
[0033] The main portions 130 and 150 are deeper than the friction
reducing portions 132, 152, and extend down through the cover 44 to
the inlet and outlet connection ports. The main portions have
axially extending walls 160, 162 and the shallow portions have
bottom walls 164, 166 extending radially from the axially extending
walls 160, 162.
[0034] The friction-reducing cutouts, e.g. cutout 80, and the
friction reducing portions, e.g. friction reducing portion 102, may
both be included in the pump 20 (as is shown in the illustrated
embodiment) or only one of these features may be present. For
example, an oil pump may include both the circumferential wall
cutouts and the friction reducing portions, or an oil pump may only
include the circumferential wall cutouts, or an oil pump may only
include the friction reducing portions. Additionally, each of the
ports need not include the friction-reducing portions. For example,
the oil pump may only include friction reducing portions on the
outlet port 50 and the outlet shadow port 68, or the oil pump may
only include friction-reducing portions on the inlet port 48 and
the inlet shadow port 66.
[0035] While the oil pump 20 is shown as an electronic pump for a
transmission, the friction-reducing techniques described herein are
broadly applicable to any gerotor-type oil pump. That is, the oil
pump 20 is not limited to any particular application or power
source. For example, the above teachings may be applied to a
gerotor-type engine oil pump or to a mechanically powered
gerotor-type oil pump for a transmission. This disclosure is also
not limited to the automotive field and can be used in gerotor-type
oil pumps for other fields.
[0036] While exemplary embodiments are described above, it is not
intended that these embodiments describe all possible forms
encompassed by the claims. The words used in the specification are
words of description rather than limitation, and it is understood
that various changes can be made without departing from the spirit
and scope of the disclosure. As previously described, the features
of various embodiments can be combined to form further embodiments
of the invention that may not be explicitly described or
illustrated. While various embodiments could have been described as
providing advantages or being preferred over other embodiments or
prior art implementations with respect to one or more desired
characteristics, those of ordinary skill in the art recognize that
one or more features or characteristics can be compromised to
achieve desired overall system attributes, which depend on the
specific application and implementation. These attributes can
include, but are not limited to cost, strength, durability, life
cycle cost, marketability, appearance, packaging, size,
serviceability, weight, manufacturability, ease of assembly, etc.
As such, to the extent any embodiments are described as less
desirable than other embodiments or prior art implementations with
respect to one or more characteristics, these embodiments are not
outside the scope of the disclosure and can be desirable for
particular applications.
[0037] The following is a list of reference numbers shown in the
Figures. However, it should be understood that the use of these
terms is for illustrative purposes only with respect to one
embodiment. And, use of reference numbers correlating a certain
term that is both illustrated in the Figures and present in the
claims is not intended to limit the claims to only cover the
illustrated embodiment.
PARTS LIST
[0038] 20 oil pump [0039] 22 housing [0040] 26 pump cavity [0041]
28 back face [0042] 30 wall [0043] 32 pump set [0044] 34 drive
rotor [0045] 36 annulus [0046] 38 external lobes [0047] 40 internal
lobes [0048] 42 fluid chambers [0049] 44 cover [0050] 46 front face
[0051] 48, 50 outlet ports [0052] 60 motor [0053] 62 motor cavity
[0054] 64 driveshaft [0055] 66, 68 shadow ports [0056] 70 wall
[0057] 72 high-pressure side [0058] 74 low-pressure side [0059] 75
dividing line [0060] 76, 78 segment [0061] 80, 82, 84 cutouts
[0062] 86 inner surface [0063] 87 bumper [0064] 88 first surface
[0065] 90 back surface [0066] 92 second surface [0067] 94 end
[0068] 96 ledge [0069] 100, 120, 130, 150 main portion [0070] 102,
122, 132, 152 friction-reducing portion [0071] 104, 108, 124, 134,
138, 154, 158 inner arcuate edge [0072] 105 root circle [0073] 106,
126, 136, 156 outer arcuate edge [0074] 107 bottoms [0075] 110, 140
vent [0076] 160, 162 axially extending walls [0077] 164, 166 bottom
walls
* * * * *