U.S. patent application number 10/316245 was filed with the patent office on 2003-08-28 for pump with integral motor and impeller.
Invention is credited to Chu, Yu-Sen James, Dilisi, Lori Ann.
Application Number | 20030161739 10/316245 |
Document ID | / |
Family ID | 27760296 |
Filed Date | 2003-08-28 |
United States Patent
Application |
20030161739 |
Kind Code |
A1 |
Chu, Yu-Sen James ; et
al. |
August 28, 2003 |
Pump with integral motor and impeller
Abstract
An integral motor and pump includes a casing having an inlet and
an outlet, and a motor mounted within the casing. The motor
includes a rotor member and a stator member. A tubular shaft
circumscribing a central axis is received and fixed within the
rotor. The tubular shaft is formed from a pair of axially
overlapping tubular end portions and has an inner peripheral wall.
An impeller is longitudinally spaced and press-fit within the inner
peripheral wall of the shaft. The impeller includes a central,
axially-extending body and a series of radially projecting blades,
with each blade extending radially outward from the central body to
the inner peripheral wall. When the motor is energized, the rotor
turns, which in turn causes the impeller to rotate and draw fuel
through the pump. When the motor is off, a flow path is maintained
through the pump between the blades of the impeller.
Inventors: |
Chu, Yu-Sen James;
(Westlake, OH) ; Dilisi, Lori Ann; (Olmsted Falls,
OH) |
Correspondence
Address: |
CHRISTOPHER H HUNTER
PARKER-HANNIFIN CORPORATION
6035 PARKLAND BOULEVARD
CLEVELAND
OH
44124-4141
US
|
Family ID: |
27760296 |
Appl. No.: |
10/316245 |
Filed: |
December 10, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60339377 |
Dec 10, 2001 |
|
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|
Current U.S.
Class: |
417/356 |
Current CPC
Class: |
F04D 13/0646 20130101;
F04D 13/0653 20130101; F04D 3/00 20130101 |
Class at
Publication: |
417/356 |
International
Class: |
F04B 017/00 |
Claims
What is claimed is:
1. A fuel pump, comprising: a casing having an inlet and an outlet,
a motor mounted within said casing and including a rotor member and
a stator member, a tubular shaft circumscribing a central axis
received within the rotor and fixed to and rotatable therewith,
said tubular shaft defining an inner peripheral wall therein, an
impeller axially supported and press-fit within said inner
peripheral wall of the shaft, said impeller including a central,
axially-extending body and a series of radially projecting blades,
each blade extending radially outward from said central body to
said inner peripheral wall, and electrical connection means for
energizing said motor to cause rotor rotation and in turn to cause
impeller rotation.
2. The fuel pump as in claim 1, and further including a vaned
diffuser supported in the pump on a downstream side of the
impeller.
3. The fuel pump as in claim 1, wherein the shaft includes
radially-inward projecting first and second shoulders forming axial
stops for each end of the impeller, the stops axially locating the
impeller within the tubular shaft.
4. The fuel pump as in claim 1, wherein the tubular shaft includes
a pair of spaced apart annular flange members, projecting radially
outward from the shaft, and the rotor member is located between
said annular flange members.
5. The fuel pump as in claim 4, and further including a pair of
bearing members radially outwardly supporting said tubular shaft in
said casing, said bearing members each located on an axial opposite
side of said flange members from the rotor member, said flange
members each constituting an axial support for the bearing
members.
6. The fuel pump as in claim 5, wherein a bearing sleeve fixed to
the casing supports each bearing member on i) a radially outer
side; and ii) an axial end.
7. The fuel pump as in claim 6, wherein each bearing member is
fixed against rotation relative to the bearing sleeve by a key
member.
8. The fuel pump as in claim 1, wherein the shaft comprises an
inlet end portion and an outlet end portion, each portion being
concentrically aligned and having an axially overlapping section,
said portions being fixed together along the overlapping
section.
9. The fuel pump as in claim 8, wherein the central shaft includes
a pair of spaced apart, annular flange members, projecting radially
outward from the shaft, and each portion carries one of the flange
members, and the rotor member is located between said annular
flange members.
10. The fuel pump as in claim 8, wherein the outlet end portion
includes a first radially-inward projecting shoulder forming a
first axial stop for one end of the impeller, and the inlet end
portion includes a second radially-inward projecting shoulder
forming a second axial stop for another end of the impeller, the
first and second stops axially locating the impeller within the
tubular shaft.
11. The fuel pump as in claim 1, wherein the shaft comprises an
inlet end portion and an outlet end portion, each portion being
concentrically aligned and having an axially overlapping section,
said portions being fixed together along the overlapping section;
and wherein the central shaft includes a pair of spaced apart,
annular flange members, projecting radially outward from the shaft,
and each portion carries one of the flange members; and the rotor
member is located between said annular flange members; and further
including a pair of bearing members radially outwardly supporting
said tubular shaft in said casing, said bearing members each
located on an axial opposite side of said flange members from the
rotor member, said flange members each constituting an axial
support for the bearing members; and a bearing sleeve fixed to the
casing supports each bearing member on i) a radially outer side;
and ii) an axial end; and the outlet end portion includes a first
radially-inward projecting shoulder forming a first axial stop for
one end of the impeller, and the inlet end portion includes a
second radially-inward projecting shoulder forming a second axial
stop for another end of the impeller, the first and second stops
axially locating the impeller within the tubular shaft.
Description
CROSS-REFERENCE TO RELATED CASES
[0001] The present application claims the benefit of the filing
date of U.S. Provisional Application Serial No. 60/339,377; filed
Dec. 10, 2001, the disclosure of which is expressly incorporated
herein by reference
FIELD OF THE INVENTION
[0002] The present invention relates to centrifugal fuel pumps,
such as for aircraft applications.
BACKGROUND OF THE INVENTION
[0003] Centrifugal pumps are commonly used to move fluid from one
location to another, for example to remove fuel from an aircraft
fuel tank and provide the fuel to remote equipment, e.g., to a
turbine engine, or to move the fuel from tank to tank. Such pumps
typically have a motor and an impeller enclosed within a casing or
housing. The motor rotates the impeller, which in turn draws fluid
through an inlet opening in the casing and discharges the fluid
(typically under pressure) through an outlet opening. One common
pump has an in-line design, where the impeller includes an
axially-extending stem coupled to the drive shaft of the motor.
Radially extending helical blades are formed integrally with the
stem of the impeller and are enclosed by an axially-extending
cylindrical shroud or sleeve. The stem and helical blades rotate
within the shroud to draw the fluid into a volute chamber in the
housing. The volute chamber converts the kinetic energy imparted to
the fuel by the impeller into pressure and discharges-the fluid
through the outlet in the housing. Such centrifugal pumps are
available from a wide variety of manufacturers, including the
assignee of the present invention. Exemplary pumps are also shown
in Chu, U.S. Pat. No. 5,427,501; Carter, U.S. Pat. No. 3,652,186;
Ridland, U.S. Pat. No. 2,846,952; Kalashnikov, U.S. Pat. No.
4,275,988; Davis et al, U.S. Pat. No. 4,142,839; and Bell, U.S.
Pat. No. 3,038,410.
[0004] In the Chu pump, as in many others, the volute chamber
surrounds the impeller. A discharge housing is fluidly connected
and fixedly coupled to a side of the casing, and directs the flow
to the appropriate location (e.g., another fuel tank, to an engine,
etc.). The volute chamber and discharge housing thereby take up
additional space in the tank, and require additional components.
They also add weight to the pump, and overall, increase the total
cost of the pump and the system.
[0005] In addition, a common requirement in aircraft applications
is to maintain a fuel path if the pump is not operational, for
example to maintain fuel flow to the engine in the event of a pump
failure. Many pumps, particularly in-line pumps with shaft-mounted
impellers, impede or prevent fuel flow through the pump when the
pump is off. To create such a flow path, a by-pass fluid circuit is
plumbed into the system. The bypass fluid circuit includes tubing,
valves and sometimes even additional pump(s) that are used when the
pump is off. Adding a bypass circuit in the system, of course, also
adds space, requires additional components, and increases the
weight and cost of the pump.
[0006] In light of the drawbacks noted above, the pumps useful for
aircraft applications tend to be large in size, complex, heavy and
costly. Thus, it is believed there is a demand in the aircraft
industry for an in-line centrifugal pump that is compact, light in
weight, and has a structure which is simple to assemble and repair,
and low cost to manufacture.
SUMMARY OF THE INVENTION
[0007] The present invention provides a novel and unique in-line
centrifugal pump having a motor with an integral impeller. The
impeller draws fluid from an inlet to an outlet when the pump is
operational, while a flow path is maintained through the pump (with
negligible pressure drop) when the pump is not operational. The
pump is easy to assemble, has good reliability due to few rotating
parts, and has a lower weight due to the compactness of the design.
The cost of the pump is thereby reduced.
[0008] According to the principles of the present invention, the
pump includes a casing having an inlet and an outlet. A motor is
mounted within the casing and includes an annular, rotatable rotor
member and fixed stator member. A tubular shaft circumscribing a
central axis is received within the rotor, and is fixed thereto.
The shaft is co-axial with the inlet and outlet of the casing, and
defines an inner peripheral wall. An impeller is longitudinally
spaced and press-fit within the inner peripheral wall of the shaft.
The impeller includes a central, axially-extending body and a
series of helical blades, where each blade extends radially outward
from the central body to the inner peripheral wall. When the motor
is energized, the rotor turns, which in turn causes the impeller to
rotate and draw fuel through the pump from the inlet to the
outlet.
[0009] When the motor stops, a flow path is maintained between the
helical blades of the impeller from the inlet port to the outlet
port. It has been found that there is little if no pressure drop
across the impeller when the pump is non-operational which
eliminates the need for a separate by-pass circuit.
[0010] The shaft includes radially-inward projecting first and
second shoulders forming axial stops for the impeller. The stops
axially locate the impeller within the hollow central shaft.
Preferably the shaft comprises a tubular inlet end portion and a
tubular outlet end portion, with each portion being concentrically
aligned and having an axially overlapping section which allows the
end portions to be fixed together. Each end portion carries one of
the shoulders forming the shoulders for the impeller.
[0011] The central shaft further includes a pair of spaced apart,
annular flange members, projecting radially outward from the shaft.
Each of the inlet end and outlet end portions also carries one of
the flange members. The rotor member is located between the annular
flange members.
[0012] A pair of bearing members outwardly support the tubular
shaft in the casing. The bearing members are located on the axial
opposite side of said flange members from the rotor member, with
the flange members each constituting an axial support for the
bearing members.
[0013] Preferably, a vaned diffuser is supported in the tubular
shaft on the downstream side of the impeller to optimize the
pressure conversion at the impeller exit.
[0014] Thus, as described above, an in-line centrifugal pump is
provided that is easy to assemble, has good reliability due to
fewer rotating parts, and has a lower weight due to the compactness
of the design. It is believed this reduces the costs associated
with the pump.
[0015] Further features of the present invention will become
apparent to those skilled in the art upon reviewing the following
specification and attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a side view of a pump constructed according to the
principles of the present invention;
[0017] FIG. 2 is an end view of the pump of FIG. 1 from the inlet
end;
[0018] FIG. 3 is an end view of the pump of FIG. 1 from the outlet
end;
[0019] FIG. 4 is a cross-sectional side view of the pump;
[0020] FIG. 5 is an enlarged, cross-sectional side view of a
portion of the pump.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Referring to the drawings, and initially to FIGS. 1-4, a
centrifugal pump is illustrated generally at 10, constructed
according to the principles of the present invention. The
centrifugal pump includes an outer pump casing or housing,
indicated generally at 12, which encloses a motor, indicated
generally at 14, and an impeller, indicated generally at 16. The
centrifugal pump is preferably mounted in a conventional manner to
a tank floor or end wall, or other appropriate support surface.
Mounting pads or feet 23 extend radially outward from the bottom of
housing 12 and can be attached to the support surface in a
conventional manner, such as with bolts 24.
[0022] The motor casing 12 includes a body 25, having a somewhat
cylindrical configuration, and being enclosed at one end by an
annular inlet cover 26, and at the other end by an annular outlet
cover 27. Inlet cover 26 includes an annular elongated neck portion
28 which defines an inlet port 29; while outlet cover 27 includes
an annular elongated neck portion 30 which defines an outlet port
32. Neck portions 28, 30 are each concentrically aligned with each
other and with the central axis "A" of the casing 12. Appropriate
bolts, as at 34, fix the covers 26, 27 to the body 25, and
appropriate O-ring seals as at 35 are provided between these
components to ensure a fluid-tight enclosure.
[0023] The motor 14 is preferably a three-phase AC wet motor of a
suitable explosion-proof sealed type for submerged operation, and
includes thermal fuses for each phase. The motor 14 is located
within an internal chamber 39 of the casing, and includes an
annular rotor 41 surrounded by an annular stator 43. Stator 43 is
sealed and fits closely within the main body 25 of the casing, and
is located and fixed against rotation with respect to casing 12 by
an elongated L-shaped key 45, which fits into a slot in the stator
and a corresponding axial groove in the casing. An insulator layer
47 can be provided, as appropriate, between stator 43 and main body
25 as a spark arrester. Stator 43 is preferably of an otherwise
conventional type, with wound coils embedded in a potting
compound.
[0024] Rotor 41 is also preferably conventional in design, and
closely surrounds a hollow tubular shaft, indicated generally at
50. Conventional means are used to fix the rotor with respect to
the shaft, such as elongated ribs or knurls on the inside diameter
of the rotor received in indentations or serrations along the
outside diameter of the shaft. The rotor could also be keyed to the
shaft such as described above with the stator and housing; or
generally, any other means could be used to prevent relative
rotation and axial movement of the rotor along the shaft.
[0025] Shaft 50 circumscribes the central axis "A" of the pump, and
defines a main fuel passage 51 through the pump shaft from inlet
port 29 to outlet port 32. Shaft 50 preferably comprises a
two-piece design, with an inlet end portion 52 toward inlet port
29, and an outlet end portion 54 toward outlet port 32. The outlet
end portion 54 is coaxial with and axially overlaps a section of
the inlet end portion 52. The outer end portion 54 can be fixed to
the inlet end portion 52, such as by welding.
[0026] A pair of annular flanges 58, 59, project radially outward
from shaft 50. Each flange 58, 59 has a tapered surface 60, 61,
respectively (see FIG. 5), which surfaces face inwardly toward each
other. The flanges 58, 59 are axially spaced apart sufficient to
closely receive rotor 41, and the tapered surfaces facilitate
axially locating rotor 41 along shaft 50. Preferably, one flange 58
is provided integral (preferably unitary) with outlet end portion
54; while the other flange 59 is provided integral (preferably
unitary) with inlet end portion 52.
[0027] Shaft 50 is supported on a bearing structure comprising a
first carbon thrust/radial bearing 63 and a second carbon
thrust/radial bearing 64. First bearing 63 has one axial end
located against a flat, outwardly-facing side 64a (FIG. 5) of
flange 58 opposite from rotor 41, and supported on its outer
diameter by the annular base 65 of a first bearing sleeve 66. A
shoulder 67 projects radially inward from base 65 to support the
other axial end of first bearing 63. First bearing sleeve 66 has a
radially outward projecting annular arm 68 which is fixed to a
sidewall 69 of body 25 via bolts as at 70.
[0028] Likewise, second bearing 64 has one axial end located
against a flat, outwardly-facing side 72 (FIG. 5) of flange 59
opposite from rotor 41, and is supported on its outer diameter by
the annular base 74 of a second bearing sleeve 75, and at its other
axial end by radial shoulder 76. Second bearing sleeve 75 also has
a radially outward projecting annular arm 77 which is fixed to a
sidewall 78 of inlet cover 26 via bolts as at 80. Straight pins 82
are provided between bearings 63, 64, and their respective bearing
sleeves 66, 75, to locate and prevent relative rotation
thereof.
[0029] Bearings 63, 64, in conjunction with flanges 58, 59 and
sleeves 66, 75 properly axially and radially locate the shaft 50,
and allow smooth rotation thereof.
[0030] A slight gap or clearance is provided between the ends of
shaft 50 and the adjacent portions of covers 28, 30, to prevent
catching and binding, and to allow fluid communication/leakage into
chamber 39 for lubrication of the bearings and to cool the motor.
The use of carbon bearings, and the bearing design described above,
allows the motor to dry-run, in the event of a drop in fuel,
without overheating or damage to the bearings because of a loss of
cooling fluid.
[0031] The impeller 16 preferably comprises an inducer-type
impeller which is received within and coupled to hollow tubular
shaft 50. To this end, referring now to FIG. 5, the impeller
includes a central, axially-extending body 84, having a conical
tapered shape, with its narrow end 85 toward the inlet port 29, and
its wider end 86 toward the outlet port 32; and a series of helical
or spiral blades or vanes, as at 87, which project radially outward
from central body 84 to shaft 50. As should be well-know, the
blades form channels which are configured to move fuel received in
inlet port 29 toward outlet port 32. Blades 87 are preferably
formed unitary (in one piece) with body 84, and have a common
radial dimension such that they are all closely received, and
preferably press-fit, within the shaft 50, and preferably within
the outlet end portion 54 of the shaft 50, such that the impeller
rotates with the rotation of shaft 50. The blades 87 preferably
extend the entire length of the body 84 from the narrow end 85 to
the wider end 86 and can be configured in one or more flights.
Preferably no additional mechanical attachment is necessary between
the impeller and the shaft.
[0032] A first, radially-inward directed annular shoulder 88 is
provided in outlet end portion 54 to axially locate and support one
axial end 86 of impeller 16 in shaft 50; while a second,
radially-inward directed annular shoulder 89 is provided by the
radially smaller end of inlet end portion 52 to axially locate and
support the opposite axial end 85 of impeller 16 in shaft 50.
[0033] The dimensions of the central body 84, blades 87 and shaft
50 are preferably chosen so as to maximize the capacity of the
impeller for a particular application. These characteristics, as
well as the rating of motor 14, can be easily determined by those
of ordinary skill in the art based on such factors as the
dimensions and volumetric capacity of the pump and the intended
rotational speed of the impeller.
[0034] The assembly of the pump is facilitated by the above design.
Specifically, the rotor 41 and stator 43 are initially located over
outlet end portion 54 of shaft 50, with one end of the rotor being
supported against flange 58. The impeller 16 is then inserted
within the outlet end portion 54, with one end 86 of the impeller
being supported against first shoulder 88. The inlet end portion 52
is then slid into the outlet end portion, with the other flange 59
supporting the other end of the rotor 41, and the second shoulder
89 supporting the opposite end 85 of impeller 16. The inlet end
portion 52 and other end portion 54 are then fixed together, such
as by welding. Bearing sleeves 66, 75 are attached to their
respective sidewalls 69, 78; and the motor and impeller subassembly
is then inserted within main body 25. Bolts 34 are then tightened
down to fix covers 28, 30 to opposite ends of the main body with
bearings 63, 64 located between their respective bearing sleeve and
shaft portion, to enclose the motor and impeller within the
housing, and allow relative rotation of the rotor and impeller
therewith.
[0035] As should be appreciated, the assembly of the motor and
impeller is thereby simplified, with fewer parts to reduce cost,
reduce complexity, and reduce the necessity of repair and
maintenance.
[0036] Referring again to FIG. 4, a vaned diffuser, indicated
generally at 94, can be located in outlet cover 30, downstream from
impeller 16, if necessary or desirable, to diffuse the fuel flow
through the pump. Such a diffuser is illustrated as including a
central, axial body 95, which narrows toward the outlet port 32,
and a series of radial vanes 96. Diffuser 94 can be attached to
annular neck portion 30 in an appropriate manner, such as by
press-fit or welding.
[0037] Remote electrical communication with the motor of the pump
is provided by an electrical connector, indicated at 98 in FIGS.
1-3. Electrical connector 98 is conventional in design, and can
include for example, a multi-pronged connection for control of each
phase of the motor. Other electrical connectors, or a hard-wiring
connection of the pump, can also be used.
[0038] Also if necessary or desirable, a pressure transducer,
indicated generally at 108, can be mounted to the housing 14 via
bolts 109, to measure the pressure of fuel flow through the pump
for control purposes. A passage 110 (FIG. 4) is provided internally
of the casing into main fuel passage 51 for this purpose. Pressure
transducer 108 is preferably of a conventional type,
commercially-available in the marketplace, and chosen so as to be
appropriate for the particular application. Electrical connector 98
can include additional prongs for communication with the pressure
transducer, or the pressure transducer can be separately
controlled.
[0039] While a specific type of motor has been described, it should
be apparent to those skilled in the art that the motor could also
comprise rotor and stator configurations other than as described
above; as well as drive means such as an air turbine, a hydraulic
motor, or any other type of means for transferring energy to
mechanical motion. In any case, the dynamic requirements of the
motor can be easily determined knowing the requirements of the
pump, e.g., the differential head necessary, the running speed, the
liquid characteristics, and the available power supply.
[0040] As should be appreciated, application of a control signal
through connector 98 will energize the motor and cause rotation of
rotor 41. This in turn will cause rotation of impeller 16, which
will draw fuel from inlet port 29 and discharge the fuel through
outlet port 32, typically under pressure. When the motor is
stopped, the rotor and impeller will likewise stop rotating. As can
be seen in FIG. 2, a flow path through passage 51 is maintained
between the impeller blades 87 to maintain fuel flow to the
downstream components of the system (e.g., to the engine). It has
been found that the impeller blades do not cause significant
pressure drop for the fuel flow, which thereby eliminates the need
for a separate by-pass circuit.
[0041] While the present invention is particularly suited to be
used as a fuel pump for aircraft applications, it is believed the
pump may also be appropriate for other aerospace and non-aerospace
applications where it is necessary to move a fluid from one
location to another.
[0042] Thus, as described above, an in-line centrifugal pump is
provided that is easy to assemble, has good reliability due to
fewer rotating parts, and has a lower weight due to the compactness
of the design. The pump is thereby more cost-effective to
produce.
[0043] The principles, preferred embodiments and modes of operation
of the present invention have been described in the foregoing
specification. The invention which is intended to be protected
herein should not, however, be construed as limited to the
particular form described as it is to be regarded as illustrative
rather than restrictive. Variations and changes may be made by
those skilled in the art without departing from the scope and
spirit of the invention as set forth in the appended claims.
* * * * *