U.S. patent application number 10/306585 was filed with the patent office on 2004-05-27 for gerotor fuel pump having primary and secondary inlet and outlet portings.
This patent application is currently assigned to Visteon Global Technologies Inc.. Invention is credited to Castle, Harold L., Kempfer, Stephen T., Yu, DeQuan.
Application Number | 20040101427 10/306585 |
Document ID | / |
Family ID | 29780426 |
Filed Date | 2004-05-27 |
United States Patent
Application |
20040101427 |
Kind Code |
A1 |
Yu, DeQuan ; et al. |
May 27, 2004 |
Gerotor fuel pump having primary and secondary inlet and outlet
portings
Abstract
The present invention involves a gear assembly of a fuel pump
for improved supply of fuel to an automotive engine from a fuel
tank. The assembly includes an inner gear and an outer gear
matingly cooperating with the inner gear for rotation about an
axis. The assembly further includes a pump cover including a cover
surface adjacent the inner and outer gears and a pump body
including a body surface adjacent the inner and outer gears
opposite the pump cover. The cover surface has a primary inlet
porting and a secondary outlet porting formed thereon and separated
between seal areas. The body surface of the pump body includes a
primary outlet porting and a secondary inlet porting separated
between seal areas. In use, the inlet portings and the outlet
portings of the pump body and the pump cover cooperate together,
respectively, such that fuel entering through the inlet portings
pass therethrough at a rate at which the gear assembly moves. Also,
the outlet portings of the pump body and the pump cover cooperate
together to allow fuel to pass therethrough at the rate at which
the gear assembly moves.
Inventors: |
Yu, DeQuan; (Ann Arbor,
MI) ; Castle, Harold L.; (Dexter, MI) ;
Kempfer, Stephen T.; (Canton, MI) |
Correspondence
Address: |
VISTEON 29074
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60611
US
|
Assignee: |
Visteon Global Technologies
Inc.
|
Family ID: |
29780426 |
Appl. No.: |
10/306585 |
Filed: |
November 27, 2002 |
Current U.S.
Class: |
418/15 ;
418/171 |
Current CPC
Class: |
F04C 15/0049 20130101;
F04C 2/102 20130101; F04C 15/06 20130101 |
Class at
Publication: |
418/015 ;
418/171 |
International
Class: |
F04C 002/00; F04C
018/00; F01C 001/10 |
Claims
1. A gear assembly of a fuel pump for supplying fuel to an
automotive engine from a fuel tank, the assembly comprising: an
inner gear; an outer gear matingly cooperating with the inner gear
for rotation about an axis; a pump cover including a cover surface
adjacent the inner and outer gears, the cover surface having an
inlet aperture formed therethrough, the cover surface having a
primary inlet porting and a secondary outlet porting formed
thereon, the primary inlet porting being formed from the inlet
aperture at a first inlet end and radially extending therealong at
a second inlet end, the secondary outlet porting radially extending
between first and second outlet ends; a pump body including a body
surface adjacent the inner and outer gears opposite the pump cover,
the body surface having an outlet aperture formed therethrough, the
body surface having a primary outlet porting and a secondary inlet
porting formed thereon, the primary outlet porting being formed at
the outlet aperture and in alignment with the secondary outlet
porting, the primary and secondary inlet portings being configured
to allow fuel to pass therethrough at a rate at which the gear
assembly moves, the primary outlet porting radially extending
therealong in alignment with the secondary outlet porting, the
secondary inlet porting being in alignment with the primary inlet
porting.
2. The assembly of claim 1 wherein the primary and secondary outlet
portings are configured to allow fuel to pass therethrough at the
rate at which gear assembly rotates.
3. The assembly of claim 1 wherein the inner gear has a
substantially disc shape with an outside camming surface and having
an inner gear cover face and an inner gear body face.
4. The assembly of claim 3 wherein the outer gear has an annular
wall having an inside camming surface to matingly cooperate with
the outside camming surface of the inner gear for rotation about an
axis, the outer gear having an outer gear cover face and an outer
gear body face.
5. The assembly of claim 4 wherein the cover surface is adjacent
the inner gear cover face and the outer gear cover face.
6. The assembly of claim 1 wherein the inner gear has a
substantially disc shape with an outside camming surface and having
an inner gear cover face and an inner gear body face, the inner
gear having a center aperture formed therethrough defining an axis
of rotation perpendicular to the inner gear cover face and the
inner gear body face.
7. The assembly of claim 6 wherein the outer gear has a
substantially planar shape, the outer gear including an annular
wall having an inside camming surface slidably engaging about the
outside camming surface to matingly cooperate with the inner gear
for rotation about the axis, the outer gear having an outer gear
cover face and an outer gear body face.
8. The assembly of claim 1 wherein the primary inlet porting has a
radial width increasing toward the second inlet end.
9. The assembly of claim 8 wherein the primary inlet porting has a
first depth at the first inlet end and decreasing toward the second
inlet end to a second depth.
10. The assembly of claim 1 wherein the primary inlet porting has a
first varying width and a first varying depth.
11. The assembly of claim 1 wherein the primary inlet porting has a
depth of about 4.0 millimeters at the first inlet end and
decreasing to about 2.0 millimeters at the second inlet end.
12. The assembly of claim 1 wherein the secondary outlet porting
has a depth of about 1.0 millimeters.
13. The assembly of claim 1 wherein the secondary outlet porting
has a substantially constant depth.
14. The assembly of claim 4 wherein the body surface is adjacent
the inner gear body face and the outer gear body face.
15. The assembly of claim 1 wherein the primary outlet porting has
a radial width decreasing toward the second outlet end.
16. The assembly of claim 15 wherein the primary outlet porting has
a third depth at the first outlet end and increasing to the second
outlet end to a fourth depth.
17. The assembly of claim 1 wherein the primary outlet porting has
a second varying width and a second varying depth.
18. The assembly of claim 1 wherein the primary outlet porting has
a depth of about 2.0 millimeters at the first outlet end and
increasing to about 4.0 millimeters at the second outlet end.
19. The assembly of claim 1 wherein the secondary inlet porting has
a depth of about 1.0 millimeters.
20. The assembly of claim 1 wherein the secondary inlet porting has
a substantially constant depth.
21. The assembly of claim 1 wherein the primary inlet porting and
the secondary outlet porting of the pump cover and the primary
outlet porting and the secondary inlet porting of the pump body are
separated by seal areas.
22. The assembly of claim 21 wherein each of the seal areas is
about 0.93 pitch length of the inner gear.
23. A gear assembly for a fuel pump for supplying fuel to an
automotive engine from a fuel tank, the assembly comprising: an
inner gear including a substantially disc shape with an outside
camming surface and having an inner gear cover face and an inner
gear body face; an outer gear including an annular wall having an
inside camming surface to matingly cooperate with the outside
camming surface of the inner gear for rotation about an axis, the
outer gear having an outer gear cover face and an outer gear body
face; a pump cover including a cover surface adjacent the inner
gear cover face and the outer gear cover face, the cover surface
having an inlet aperture formed therethrough, the cover surface
having a primary inlet porting and a secondary outlet porting
formed thereon, the primary inlet porting being formed from the
inlet aperture at a first inlet end and radially extending
therealong at a second inlet end, the secondary outlet porting
radially extending between first and second outlet ends; and a pump
body including a body surface adjacent the inner gear body face and
the outer gear body face, the body surface having an outlet
aperture formed therethrough, the body surface having a primary
outlet porting and a secondary inlet porting formed thereon, the
primary outlet porting being formed at the outlet aperture and in
alignment with the secondary outlet porting, the primary outlet
porting radially extending therealong in alignment with the second
outlet end, the secondary inlet porting being in alignment with the
primary inlet porting, the primary and secondary inlet portings
being configured to allow fuel to pass therethrough at a rate at
which the gear assembly rotates;
24. The assembly of claim 22 wherein the primary and secondary
outlet portings are configured to allow fuel to pass therethrough
at the rate at which the gear assembly rotates.
25. A gerotor fuel pump for supplying fuel to an automotive engine
from a fuel tank, the fuel pump comprising: a pump housing; a motor
mounted within the housing and having a shaft extending therefrom;
an inner gear disposed within the housing; an outer gear disposed
within the housing and matingly cooperating with the inner gear for
rotation about an axis; a pump cover mounted within an end of the
housing and including a cover surface adjacent the inner and outer
gears, the cover surface having an inlet aperture formed
therethrough, the cover surface having a primary inlet porting and
a secondary outlet porting formed thereon, the primary inlet
porting being formed from the inlet aperture at a first inlet end
and radially extending therealong at a second inlet end, the
secondary outlet porting radially extending between first and
second outlet ends; a pump body mounted within the housing and
having a bore through which the shaft extends, the pump body
including a body surface adjacent the inner and outer gears
opposite the pump cover, the body surface having an outlet aperture
formed therethrough, the body surface having a primary outlet
porting and a secondary inlet porting formed thereon, the primary
outlet porting being formed at the outlet aperture and in alignment
with the secondary outlet porting, the primary and secondary inlet
portings being configured to allow fuel to pass therethrough at a
rate at which the gear assembly rotates, the primary outlet porting
radially extending therealong in alignment with the secondary
outlet porting, the secondary inlet porting being in alignment with
the primary inlet porting.
26. The fuel pump of claim 25 wherein the primary and secondary
outlet portings are configured to allow fuel to pass therethrough
at the rate at which the gear assembly rotates.
27. The fuel pump of claim 25 wherein the inner gear has a
substantially disc shape with an outside camming surface and having
an inner gear cover face and an inner gear body face.
28. The fuel pump of claim 27 wherein the outer gear has an annular
wall having an inside camming surface to matingly cooperate with
the outside camming surface of the inner gear for rotation about an
axis, the outer gear having an outer gear cover face and an outer
gear body face.
29. The fuel pump of claim 28 wherein the cover surface is adjacent
the inner gear cover face and the outer gear cover face.
30. The fuel pump of claim 25 wherein the inner gear has a
substantially disc shape with an outside camming surface and having
an inner gear cover face and an inner gear body face, the inner
gear having a center aperture formed therethrough defining an axis
of rotation perpendicular to the inner gear cover face and the
inner gear body face.
31. The fuel pump of claim 30 wherein the outer gear has a
substantially planar shape, the outer gear including an annular
wall having an inside camming surface slidably engaging about the
outside camming surface to matingly cooperate with the inner gear
for rotation about the axis, the outer gear having an outer gear
cover face and an outer gear body face.
32. The fuel pump of claim 25 wherein the primary inlet porting has
a radial width increasing toward the second inlet end.
33. The fuel pump of claim 32 wherein the primary inlet porting has
a first depth at the first inlet end and decreasing toward the
second inlet end to a second depth.
34. The fuel pump of claim 25 wherein the primary inlet porting has
a first varying width and a first varying depth.
35. The fuel pump of claim 25 wherein the primary inlet porting has
a depth of about 4.0 millimeters at the first inlet end and
decreasing to about 2.0 millimeters at the second inlet end.
36. The fuel pump of claim 25 wherein the secondary outlet porting
has a depth of about 1.0 millimeters.
37. The fuel pump of claim 25 wherein the secondary outlet porting
has a substantially constant depth.
38. The fuel pump of claim 28 wherein the body surface is adjacent
the inner gear body face and the outer gear body face.
39. The fuel pump of claim 25 wherein the primary outlet porting
has a radial width decreasing toward the second outlet end.
40. The fuel pump of claim 39 wherein the primary outlet porting
has a third depth at the first outlet end and increasing to the
second outlet end to a fourth depth.
41. The fuel pump of claim 25 wherein the primary outlet porting
has a second varying width and a second varying depth.
42. The fuel pump of claim 25 wherein the primary outlet porting
has a depth of about 2.0 millimeters at the first outlet end and
increasing to about 4.0 millimeters at the second outlet end.
43. The fuel pump of claim 25 wherein the secondary inlet porting
has a depth of about 1.0 millimeters.
44. The fuel pump of claim 25 wherein the secondary inlet porting
has a substantially constant depth.
45. The fuel pump of claim 25 wherein the primary inlet porting and
the secondary outlet porting of the pump cover and the primary
outlet porting and the secondary inlet porting of the pump body are
separated by seal areas.
46. The fuel pump of claim 45 wherein each of the seal areas is
about 0.93 pitch length of the inner gear.
47. The assembly of claim 1 wherein the inlet portings have a first
pitch value and the outlet portings have a second pitch value,
wherein the first pitch value is greater than the second pitch
value.
48. The assembly of claim 47 wherein the first pitch value and the
second pitch value are at a pitch value ratio of about 3:2.
49. The gear assembly of claim 23 wherein the inlet portings have a
first pitch value and the outlet portings have a second pitch
value, the first pitch value being greater than the second pitch
value.
50. The gear assembly of claim 49 wherein the first pitch value and
the second pitch value are at a pitch value ratio of about 3:2.
51. The gerotor fuel pump of claim 25 wherein the inlet portings
have a first pitch value and the outlet portings have a second
pitch value, the first pitch value being greater than the second
pitch value.
52. The gerotor fuel pump of claim 51 wherein the first pitch value
and the second pitch value have a pitch value ratio of about 3:2.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a gear assembly of a
gerotor fuel pump for improved efficiency in supplying fuel to an
automotive engine from a fuel tank.
[0002] Gerotor fuel pumps that have a gear assembly with a ring
slidably disposed around the outer diameter have been widely used
in automotive applications. Such fuel pumps have been used because
of their low cost and relatively high efficiency.
[0003] However, the efficiency of many such fuel pumps and problems
associated therewith can still further be improved. For example,
many current gerotor fuel pumps experience pressure pulsation at an
inlet area adjacent the bottom of the fuel tank of a vehicle. As a
result, relatively high noise is experienced between the tank and
the fuel pump. Additionally, in many situations, such gerotor fuel
pumps may experience relatively high acceleration and pressure
fluctuations therethrough potentially resulting in cavitations and
reduced efficiency. Moreover, manufacturers of fuel pumps are also
concerned about avoiding potential hydraulic lock when the fuel is
at a high pressure within the pump.
BRIEF SUMMARY OF THE INVENTION
[0004] Thus, it is one aspect of the present invention to provide a
gerotor fuel pump for improved efficiency in supplying fuel to an
automotive engine from a fuel tank, wherein the gerotor fuel pump
includes an improved porting system to reduce local velocity
acceleration within the fuel pump for avoiding potential
cavitations, pressure pulsations, and relatively high noise.
[0005] It is another aspect of the present invention to provide a
gerotor or gear assembly having a porting system for improved
supply of fuel to an automotive engine from a fuel tank. In one
embodiment, the gear assembly includes an inner gear and an outer
gear matingly cooperating with the inner gear for rotation about an
axis. The assembly further includes a pump cover having a cover
surface adjacent the inner and outer gears and a pump body having a
body surface adjacent the inner and outer gears opposite the pump
cover. The cover surface has an inlet aperture formed therethrough.
The cover surface further has a primary inlet porting and a
secondary outlet porting formed thereon wherein the primary inlet
porting is formed from the inlet aperture at a first inlet end and
radially extends therealong at a second inlet end. The secondary
outlet porting radially extends between first and second outlet
ends.
[0006] In another aspect of the present invention, the gerotor or
gear assembly having a porting system includes an inlet porting and
an outlet porting, wherein the inlet porting has a greater length
than the outlet porting to reduce inlet fuel velocity, prevent
potential cavitations, and reduce noise.
[0007] The body surface of the pump body has an outlet aperture
formed therethrough. The body surface further has a primary outlet
porting and a secondary inlet porting formed thereon. The primary
outlet porting is formed at the outlet aperture. The primary and
secondary inlet portings are configured to allow fuel to pass
therethrough at a rate at which the gear assembly moves. The
primary outlet porting radially extends therealong in alignment
with the secondary outlet porting. The secondary inlet porting is
in alignment with the primary inlet porting.
[0008] In another aspect, the present invention allows for improved
efficiency by allowing fuel to pass therethrough at a rate
corresponding to the rate at which the gear assembly moves.
[0009] It is yet another aspect of the present invention to provide
a gerotor fuel pump for improved supply of fuel to an automotive
engine from a fuel tank. The fuel pump comprises a pump housing and
a motor mounted within the housing and having a shaft extending
therefrom. The fuel pump further includes the gear assembly
mentioned above. The primary outlet porting is formed at the outlet
aperture and in alignment with the secondary outlet porting. The
primary and secondary inlet portings are configured to allow fuel
to pass therethrough at a rate at which the gear assembly rotates.
The primary and secondary outlet portings are configured to allow
fuel to pass therethrough at a rate corresponding to the rate at
which the gear assembly rotates. The primary outlet porting
radially extends therealong in alignment with the secondary outlet
porting. The secondary inlet porting is in alignment with the
primary inlet porting.
[0010] The following description of the preferred embodiment of the
present invention is not intended to limit the scope of the
invention to this preferred embodiment, but rather enable any
person skilled in the art to make and use the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a cross-sectional view of a fuel pump having a
gear assembly in accordance with one embodiment of the present
invention;
[0012] FIG. 2a is an exploded inlet view of the gear assembly in
FIG. 1;
[0013] FIG. 2b is an exploded exit view of the gear assembly in
FIG. 1;
[0014] FIG. 3a is a cover surface view of a pump cover of the gear
assembly in accordance with one embodiment of the present
invention;
[0015] FIG. 3b is a cross-sectional view of the pump cover taken
along lines 3b-3b in FIG. 3a;
[0016] FIG. 3c is another cross-sectional view of the pump cover
taken along lines 3c-3c in FIG. 3a;
[0017] FIG. 3d is yet another cross-sectional view of the pump
cover taken along lines 3d-3d in FIG. 3a;
[0018] FIG. 4a is a body surface view of a pump cover of the gear
assembly in accordance with one embodiment of the present
invention;
[0019] FIG. 4b is a cross-sectional view of the pump body taken
along lines 4b-4b in FIG. 4a;
[0020] FIG. 4c is another cross-sectional view of the pump body
taken along lines 4c-4c in FIG. 4a;
[0021] FIG. 4d is yet another cross-sectional view of the pump body
taken along lines 4d-4d in FIG. 4a;
[0022] FIG. 5a is a first view of an inner gear (cover side) of the
gear assembly in accordance with one embodiment of the present
invention;
[0023] FIG. 5b is a second view of the inner gear (body side) in
accordance with the present invention;
[0024] FIG. 5c is a cross-sectional view of the inner gear taken
along lines 5c-5c in FIG. 5b;
[0025] FIG. 6a is a first view of the outer gear (cover side) of
the gear assembly in accordance with one embodiment of the present
invention;
[0026] FIG. 6b is a cross-sectional view of the outer gear taken
along lines 6b-6b in FIG. 6a;
[0027] FIG. 7a is a cover side view of the gear assembly in
accordance with the present invention; and
[0028] FIG. 7b is a cross-sectional view of the gear assembly taken
along lines 7b-7b in FIG. 7a.
DETAILED DESCRIPTION OF THE INVENTION
[0029] Referring to FIG. 1, a fuel pump of the present invention is
generally shown at 10. The fuel pump 10 includes a housing 12 and a
motor 14 mounted within the housing 12. Preferably, the motor 14 is
an electric motor with a shaft 18 extending therefrom. A gerotor or
gear assembly 20 having inner and outer gears is fitted onto the
shaft 18 and is encased within the pump housing 12 between a pump
body 22 and a pump cover 24. The gerotor assembly 20 fits onto the
shaft 18 such that the assembly is free to move axially along the
shaft 18 and rotates with the shaft 18. Therefore, the gerotor
assembly "float" between the pump cover 24 and the pump body 22.
The fuel pump is of a conventional type which is further described
in U.S. Pat. No. 6,113,360 and U.S. patent application Ser. No.
10/256,359 which are assigned to the same assignee as the present
application and are hereby incorporated by reference into the
present application.
[0030] The gerotor assembly 20 has a central axis which is
coincident with the axis of the shaft 18. The shaft 18 passes
through a shaft opening 26 in the pump body 22, through the gear
assembly 20, into a cover recess 28, and abuts a thrust button 30.
The shaft 18 is journalled within a bearing 32. The pump body 22
has a fuel outlet (not shown) leading from an outlet porting 82.
Pressurized fuel is discharged through the fuel outlet (not shown)
to and cools the motor 14 while passing over the motor 14 to a pump
outlet 42 at an end of the pump 10 which is axially opposite a fuel
inlet 44.
[0031] As shown in FIGS. 2a and 2b, the gear assembly 20, in this
embodiment, has a lifting and lubricating feature for the fuel pump
10. The gear assembly 10 includes an inner gear 50 and an outer
gear 52 which is disposed about the outer diameter of the inner
gear 50. The inner gear 50 and the outer gear 52 are in camming
relationship to cooperate with each other for supplying fuel to the
automotive engine from the fuel tank. As will be described in
greater detail below, the inner and outer gears 50, 52 are both
toothed. The inner gear 50 is toothed along its outer diameter and
the outer gear 52 is toothed along an inner wall to cooperate with
the inner gear 50. The gear assembly further includes a cram ring
54 which is slideably disposed about the outer diameter of the
outer gear. As shown, the height of the cram ring 54 determines the
distance between the pump body 22 and the pump cover 24.
[0032] FIGS. 2a and 2b illustrate an exploded view of the gear
assembly 20. As shown, the pump cover 24 generally includes a
primary inlet porting 84, seal areas 49 and 51, and a secondary
outlet porting 86. The primary inlet porting 84 is a low pressure
fuel side of the pump cover 24 and may be defined by the
configuration of the gear assembly. The secondary outlet porting 86
is a high pressure fuel side of the pump cover. As shown, each of
the seal areas 49, 51 is formed between one of the portings 84,
86.
[0033] As shown in FIGS. 2a-3d, the pump cover 24 includes a cover
surface 25 adjacent the inner and outer gears 50, 52. Specifically,
the cover surface 25 is adjacent the inner gear cover face and the
outer gear cover face. The cover surface 25 has an inlet aperture
27 and has a primary inlet porting 84 and a secondary outlet
porting 86 formed thereon. The primary inlet porting 84 is formed
from the inlet aperture 27 at a first inlet end 31 and radially
extends therealong at a second inlet end 33. The secondary outlet
porting 86 radially extends between first and second outlet ends
35, 37. The primary inlet porting 84 has a radial width which
increases toward the second inlet end 33. The primary inlet porting
84 further has a first depth at the first inlet end 31 and
decreases toward the second inlet end 33 to a second depth as it
extends along the cover surface. Thus, the primary inlet porting 84
has a varying width and a varying depth. In this embodiment, the
primary inlet porting 84 has a depth of about 4.0 millimeters at
the first inlet end 31 and tapers or decreases to about 2.0
millimeters at the second inlet end 33. The secondary outlet
porting 86 has a depth of about 1.0 millimeters, having a
substantially constant depth. As shown, the primary inlet porting
84 and the secondary outlet porting 86 of the pump cover 24 are
separated by seal areas 88, 89.
[0034] As shown in FIGS. 4a-4d, the pump body 22 generally includes
a secondary inlet porting 80, seal areas 47 and 48, and a primary
outlet porting 82 formed on the pump body surface. The secondary
inlet porting 80 is a low pressure fuel side of the pump body 22
and may be defined by the configuration of the gear assembly. The
primary outlet porting 82 is a high pressure fuel side of the pump
body 22. As shown, each of the seal areas 47, 48 is formed between
one of the portings 80, 82.
[0035] The pump body 22 includes a body surface 41 adjacent the
inner and outer gears 50, 52 opposite the pump cover 24.
Specifically, the body surface 41 is adjacent the inner gear body
face and the outer gear body face. The body surface 41 has an
outlet aperture 43 formed therethrough. The body surface 41 further
has a primary outlet porting 82 and a secondary inlet porting 80
formed thereon. The primary outlet porting 82 is formed at the
outlet aperture 43 and is in alignment with the secondary outlet
porting 86. The primary and secondary inlet portings 84, 80 are
configured to allow fuel to pass therethrough at a rate
corresponding to the rate at which the gear assembly moves or
rotates. The primary outlet porting 82 radially extends therealong
in alignment with the secondary outlet porting 86. The secondary
inlet porting 80 is in alignment with the primary inlet porting
84.
[0036] In this embodiment, the primary and secondary outlet
portings 82, 86 are configured to allow fuel to pass therethrough
at a rate corresponding to the rate at which the gear assembly
rotates. The primary outlet porting 82 has a radial width which
decreases toward the second outlet end 37. The primary outlet
porting also has a first depth at the first outlet end 35 and
flares or increases to the second outlet end 37 to a second depth.
Thus, the primary outlet porting 82 has a varying width and a
varying depth as it extends along the body surface. In this
embodiment, the primary outlet porting 82 has a depth of about 2.0
millimeters at the first outlet end 35 and increases to about 4.0
millimeters at the second outlet end 37. The primary outlet porting
and the secondary inlet porting cooperate to allow fuel to pass
therethrough at a rate at which the gear assembly rotates. The
secondary inlet porting 80 has a depth of about 1.0 millimeters,
having a substantially constant depth. In this embodiment, each of
the seal areas mentioned above is about 0.93 pitch length of the
inner gear or less than 1.0 pitch length of the inner gear.
[0037] The inlet portings and the outlet portings have
predetermined pitch values so that during normal operations, the
fuel pump allows fuel to pass therethrough at a rate corresponding
to the rate at which the gear assembly rotates. The inlet portings
have a greater pitch value than the outlet portings. For example,
the inlet and outlet portings have a pitch value ratio of
approximately 3:2, wherein the pitch value ratio is based on the
pitch of the inner gear. In this embodiment, the inlet portings
have a pitch value of 2.54 and the outlet portings have a pitch
value of 1.60.
[0038] As shown in FIGS. 2a and 2b, the inner gear 50 has a
substantially disc shape with an outside camming surface 56 which
is a first toothed surface. The inner gear further includes an
inner cover face 58 and an inner body face 60. The inner gear 50
further has a center aperture 62 formed therethrough to define an
axis A of rotation which is perpendicular to the inner cover face
58 and the inner body face 60.
[0039] In this embodiment, the inner cover face 58 has a plurality
of inner concave grooves 64 radially formed thereon and spaced
apart from each other to provide lifting or floating of the inner
gear 50 when rotating about axis A. In this embodiment, the
plurality of inner concave grooves 64 are radially aligned with
each other on the inner cover face 58 of the inner gear 50. As
shown in FIGS. 5a-5c, each of the inner concave grooves 64 is
radially formed on the inner cover face 58 and extends, for example
about 30.degree.-120.degree. and preferably about 90.degree.,
thereabout based on the number of inner concave grooves. In this
embodiment, each of the inner concave grooves 64 is separated by a
flat or planar surface in each end, for example about
5.degree.-20.degree. and preferably about 10.degree., thereabout on
the inner cover face 58 of the inner gear 50 depending on the
number of inner concave grooves.
[0040] As shown, the inner body face 60 has a plurality of inner
convex grooves 66 radially formed thereon and spaced apart from
each other. Each of the inner convex grooves 66 is opposite with a
respective inner concave groove 64 of the inner cover face 58. In
this embodiment, each of the inner convex grooves 66 is formed on
the inner body face 60 of the inner gear 50 and radially extends,
for example about 30.degree.-120 and preferably about 90.degree.,
thereabout depending of the number of inner convex grooves. Each of
the inner convex grooves 66 are convexly formed, for example about
5.degree.-60.degree. and preferably about 30.degree. on the each
end with about 30.degree. flat on the middle (see FIG. 5c), on the
inner body face 60 of the inner gear 50 based on the number of
inner convex grooves.
[0041] In this embodiment, the inner gear includes three inner
concave grooves and three inner convex grooves. However, it is to
be understood that the plurality of inner concave grooves and the
plurality of inner convex grooves may include any number of groove
greater than one groove formed on the inner gear without falling
beyond the scope or spirit of the present invention.
[0042] As shown, the inner gear 52 further includes a plurality of
exit holes 68 formed therethrough and spaced apart between each of
the inner concave grooves 64. In this embodiment, each of the exit
holes 68 is formed through one of the inner convex grooves 66 and
extends, for example about 30.degree., thereabout.
[0043] As shown in FIGS. 2, 6, and 7, the outer gear 52 has a
substantially planar shape. The outer gear 52 includes an annular
wall 70 having an inside camming surface 72. Inside camming surface
72 cammingly engages about the outside camming surface 56 of the
inner gear 50 to matingly cooperate with the inner gear 50 for
rotation about the axis A. As shown, the inside camming surface 72
is a second toothed surface which matingly cooperates with the
first toothed surface of the outside camming surface 56. In this
embodiment, the outer gear has one more tooth than the inner gear.
As shown, the inner gear and the outer gear are off-center from
each other. In this embodiment, during normal use when the gears
rotate, the camming surfaces of the gears cooperate such that the
cavities 38 changes the volume between the inlet and outlet and
that the number of separate cavities are equal to the number of the
teeth of the inner gear.
[0044] The outer gear 52 has an outer cover surface 74 and an outer
body surface 76. In this embodiment, the outer cover surface 74 has
a plurality of outer concave grooves 78 radially formed thereon and
spaced apart from each other to provide improved lifting or
floating of the outer gear 52 when rotating about the axis A. In
this embodiment, each of the outer concave grooves 78 extends about
17.degree. about the outer cover surface 74. As shown, each of the
outer concave grooves 78 is concavely formed on the outer cover
surface 74 of the outer gear 52 and extends about 17.degree.
thereabout. In this embodiment, the plurality of the outer concave
grooves are radially aligned with each other on the outer cover
surface of the outer gear.
[0045] Thus, the outside camming surface 56 has teeth formed
radially thereon and the inside camming surface 72 has teeth formed
radially thereon. The teeth of the inner gear 50 is configured to
matingly cooperate with the teeth of the outer gear 52 for rotation
of the axis A. As shown, the teeth of the outer gear 52 is greater
in number than the teeth of the inner gear 52. For example in this
embodiment, the inner gear has six teeth while the outer gear has
seven teeth. This allows rotation of the outer gear 52 about the
inner gear 50 during normal operation of the fuel pump. As shown,
the cram ring 54 is slidably disposed about the outer gear 52.
[0046] As shown in FIGS. 2 and 7, pumping cavities 38 are formed
between inside camming surface 72 of outer gear 52 and outside
camming surface 56 of the inner gear 50. In operation, when the
gear assembly rotates, the primary inlet porting 84 of the pump
cover and the secondary inlet porting 80 of the pump body feed fuel
to the cavities at which volumes increase. Moreover, the primary
outlet porting 82 of the pump body and the secondary outlet porting
86 of the pump cover receive fuel from the cavities, at which
volumes are decreases, and deliver fuel to the outlet.
[0047] The gerotor assembly is preferably made of powered metal, or
sintered metal, for example, sintered Nickel steel. It is to be
understood that the gerotor assembly could also be made from other
non-plastic materials known to those skilled in the art such as
aluminum or steel. The fuel pump can be mounted within a fuel tank
(not shown) or, alternatively, can be mounted in-line between the
fuel tank and the engine of the vehicle.
[0048] It is to be understood that the inner gear and the outer
gear are mentioned above in accordance with one embodiment of the
present invention. It is understood that the lifting feature
mentioned above of the inner and outer gears are not required in
the present invention. Thus, other embodiments without concave and
convex grooves do not fall beyond the scope or spirit of the
present invention.
[0049] The foregoing discussion discloses and describes two
preferred embodiments of the invention. One skilled in the art will
readily recognize from such discussion, and from the accompanying
drawings and claims, that changes and modifications can be made to
the invention without departing from the scope of the invention as
defined in the following claims. The invention has been described
in an illustrative manner, and it is to be understood that the
terminology which has been used is intended to be in the nature of
words of description rather than of limitation.
* * * * *