U.S. patent application number 09/738778 was filed with the patent office on 2002-06-20 for potable water pump.
Invention is credited to Medica, Carlos, Rexroth, Larry.
Application Number | 20020076337 09/738778 |
Document ID | / |
Family ID | 24969434 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020076337 |
Kind Code |
A1 |
Rexroth, Larry ; et
al. |
June 20, 2002 |
Potable water pump
Abstract
A water-cooled pump motor for delivering potable water in a
demand system includes a centrifugal pump including a volute and an
impeller in the volute, an electric motor driving the impeller
having a hollow rotor shaft, a rotor on the shaft, bearings
supporting the rotor shaft, a stator coaxially outward of the
rotor, two water impervious liners, one located within the stator
and the other coaxially outside the rotor, the liners being spaced
to define a cylindrical passageway across the rotor and a cooling
and lubricating water passageway for water to flow through the
motor including flow from the impeller between the rotor shaft and
the bearings, across the cylindrical passageway and through the
hollow rotor shaft back into the volute.
Inventors: |
Rexroth, Larry; (North
Hollywood, CA) ; Medica, Carlos; (Aurora,
OR) |
Correspondence
Address: |
John E. Wagner, Esq.
LAW OFFICES OF JOHN E. WAGNER
3541 Ocean View Boulevard
Glendale
CA
91208
US
|
Family ID: |
24969434 |
Appl. No.: |
09/738778 |
Filed: |
December 15, 2000 |
Current U.S.
Class: |
417/365 ;
417/423.8 |
Current CPC
Class: |
F04D 29/5806 20130101;
F04D 29/588 20130101; F04D 13/064 20130101; F05D 2240/61 20130101;
F04D 29/061 20130101 |
Class at
Publication: |
417/365 ;
417/423.8 |
International
Class: |
F04B 017/00; F04B
035/00; F04B 035/04 |
Claims
We claim:
1. A water cooled electric motor having a stator, a rotor shaft,
and a rotor mounted on said rotor shaft, bearings supporting said
motor shaft and cooling and lubricating passageways for circulating
water through said motor between said stator and said rotor.
2. A water-cooled electric motor as claimed in claim 1 wherein said
rotor shaft defines a water flow path through said motor.
3. A water cooled electric motor as claimed in claim 1 wherein a
first water impervious sleeve is positioned coaxially within said
stator and a second water impervious sleeve is positioned coaxially
around said rotor, said sleeves defining a generally cylindrical
passageway forming part of said cooling and lubricating passageways
through said motor.
4. A water-cooled electric motor as claimed in claim 3 wherein said
sleeves are substantially non magnetic.
5. A water-cooled electric motor as claimed in claim 1 wherein said
cooling and lubricating passageways include paths between said
bearings and said rotor shaft.
6. A water cooled electric motor as claimed in claim 1 further
comprising a volute housing, a water inlet passage to said volute
housing, a water discharge passage, an impeller in said volute
housing secured to said motor shaft and connections between said
cooling and lubricating passageways and said volute housing.
7. In a pump-motor for delivering potable water in a demand system
comprising: a housing; a volute body secured to said housing
including an inlet port and a discharge tube; an impeller in said
volute body and a first chamber adjacent said impeller; an electric
motor in said housing including a stator, a hollow rotor shaft, a
rotor secured to said rotor shaft, and first and second bearings
supporting said rotor shaft, water impervious substantially
non-magnetic liners isolating said stator from said rotor, said
liners defining a tubular path across said rotor; a lubrication and
cooling circuit through said pump-motor including fluid pathways
between said rotor shaft and said bearings, through said tubular
path and through the interior of said hollow rotor shaft to said
volute body.
8. A pump-motor as claimed in claim 7 further comprising a thrust
plate surrounding said rotor shaft adjacent one of said
bearings.
9. A pump-motor as claimed in claim 8 wherein said lubrication and
cooling circuit includes a pathway from said volute to said one
bearing, between said bearing and said rotor shaft, between said
thrust plate and said bearing and connecting with said cylindrical
path.
10. A pump-motor as claimed in claim 7 wherein said rotor is
secured to said rotor shaft by means of a hollow fastener
communicating with said hollow rotor shaft.
11. A pump rotor as claimed in claim 7 wherein said water
impervious substantially non-magnetic liners include a first liner
internal of said stator and a second liner external of said
rotor.
12. A water cooled electrically driven centrifugal pump including a
housing, a fluid inlet passage, a volute connected to said inlet
passage, an impeller for driving water from said inlet passage into
said volute, and a discharge tube connected to said volute; a
hollow rotor shaft in said housing connected to said impeller, an
axial bore through said rotor shaft, and a rotor secured to said
rotor shaft, first and second bearings supporting said rotor shaft
in said housing; a stator in said housing; a water impervious
tubular sleeve positioned on the outside of said rotor; a water
impervious sleeve positioned coaxially within said stator; said
sleeves defining a generally tubular flow path across said rotor
between said rotor and stator; a flow path from said volute and
between one of said bearings and said rotor shaft communicating
with said generally cylindrical flow path; and a flow path from
said generally cylindrical flow path and between the other of said
bearings and said rotor shaft; and an additional flow path through
the hollow interior of said rotor shaft to said volute.
13. A pump-motor as claimed in claim 12 wherein said rotor is
secured to said rotor shaft by means of a hollow fastener
communicating with the hollow interior of said rotor shaft.
14. A pump-motor as claimed in claim 12 further comprising a thrust
plate surrounding said rotor shaft adjacent one of said
bearings.
15. A pump motor as claimed in claim 12 wherein said sleeves are
substantially non magnetic.
16. A pump-motor for delivering potable water in a demand system
comprising: a housing; a volute body secured to said housing
including an inlet port and a discharge tube; an impeller in said
volute body and a first chamber adjacent said impeller; an electric
motor in said housing including a stator, a hollow rotor shaft and
a rotor secured to said rotor shaft, first and second bearings
supporting the end of said rotor shaft nearest said impeller and
the end remote from said impeller, respectively; a thrust plate
positioned between said rotor and said first bearing, and resilient
means opposing axial forces on said rotor shaft; a generally
cylindrical water impervious liner internal of said stator and a
second cylindrical water impervious liner external of said rotor,
said liners defining a generally cylindrical pathway across said
rotor; a second chamber between said rotor and said second bearing;
and a lubrication and cooling circuit through said pump motor
comprising said first chamber in said volute body receiving part of
the water pumped by said impeller, a water path from said first
chamber around a plurality of surfaces of said first bearing,
through said generally cylindrical pathway to said second chamber,
from said second chamber between said second bearing and said rotor
shaft, through the hollow interior of said rotor shaft and into
said volute body.
17. A pump-motor in accordance with claims 1, 7, 12, or 16
incorporating an expansion chamber to prevent damage to the
pump-motor when water within the pump-motor is frozen.
18. A pump-motor in accordance with claims 1, 7, 12, or 16
incorporating a thermally activated switch to remove electrical
power from the pump-motor when electrical power is applied to the
pump-motor when the pump-motor is frozen and prevented from
rotating.
Description
BACKGROUND OF THE INVENTION
[0001] In the field of potable water systems, there is a continuing
need for improvement in an electrically driven water pump that can
be used for systems of the demand type; that is, a system in which
there is a remote store of potable water which may be gravity fed
or stored in any source which does not require the water supply to
furnish water at a required outlet pressure at a desired flow rate.
Such systems are often referred to as demand systems.
[0002] The need for improvement is particularly apparent in the
case of demand systems for use on aircraft where the supply of
water is desired to be maintained at or near ambient pressure in
the aircraft rather than under pressure. This substantially reduces
the possibility of leaks from a fully pressurized tank of water or
from any of its distribution conduits, which deliver pressurized
water to any distribution point. Aircraft and their systems are
subject to the repeated cycling of ambient pressure which occurs
during the normal takeoff, flying at cruising altitude and in
landing. Repeated cycling of pressurized structures gives rise to
joint failure, particularly where the conduits and joints are at an
elevated delivery pressure rather than static ambient pressure.
[0003] Demand systems are especially useful for supplying cold and
hot potable water where the heater is similarly of the demand type
and where there is not a large volume of potable water maintained
at delivery pressure and use temperature. The combination of the
demand pump and the demand heater with a non-pressurized potable
water source present the ideal combination for supplying hot and
cold potable water aboard aircraft.
[0004] Faced with the foregoing state of the art, we have produced
an integrated pump/motor in which potable water flow provides
lubrication and cooling of the pump and motor by employing the
potable water itself without danger of contamination of the water
delivered.
[0005] We have also sought to produce a compact pump motor
combination weighing just a few pounds and having a system capable
of delivering on demand a flow of potable water at flow rates as
high as 4 to 6 gpm.
[0006] We further sought to design an integrated pump motor in a
way in which any ferrous metallic laminations are cooled by the
flow of potable water without the danger of corrosive rusting of
the laminations.
[0007] A further objective is effective cooling of the motor
windings while maintaining the windings fully insulated from the
cooling flow of potable water.
[0008] It is a further object of the invention to provide cooling
of all bearings and other rotating surfaces in the motor and in the
pump by potable water.
[0009] A further objective of the invention is to provide a path
for cooling water to flow through the pump/motor shaft after
lubricating and cooling all bearings, windings, laminations, and
the motor shaft, thereby circulating potable water back into the
incoming water stream.
[0010] A further objective of the invention is to provide for
expansion of water when water inside of the pump freezes, thereby
preventing damage to the pump from freezing water.
[0011] A further objective of the invention is to provide a means
to remove electrical power from the pump when the pump is energized
while frozen, thus preventing damage due to overheating of the
pump.
BRIEF DESCRIPTION OF THE INVENTION
[0012] Each of these objects and design objectives are accomplished
in the combination of a centrifugal pump with an electrical motor
assembly mounted on a main hollow shaft in a sealed housing in
which an annular potable water output manifold includes a port for
a lubricating water passage between the rotating and static
components of the motor within its housing. The annular output
manifold communicates with a second manifold area and continuing
flow paths between the pump/motor shaft and a cylindrical bearing
at the end of the motor assembly adjacent to the pump. The flow
paths continue between the cylindrical bearing and an anti-thrust
bearing and further extend through a gap between seals protecting
the motor stator windings and laminations and the rotor
laminations.
[0013] The potable water paths for lubrication continue through a
second chamber in the motor assembly and between the rear
cylindrical bearing and the rotor shaft, returning through the
hollow rotor shaft and through a hollow fastener which secures the
pump to the motor drive shaft and back into the potable water
output manifold. This series of potable water lubricating paths
provide lubrication between all rotating parts of the pump and
motor and adjacent non-rotating parts, and provides a recycle path
for the lubricating portion of potable water flow, which returns to
the main potable water delivery path.
[0014] An expansion chamber within the sealed housing allows for
expansion of water within the pump if the pump is operated under
freezing conditions and the water begins freezing.
[0015] A thermal switch located in the motor of the pump causes
electrical power to be removed from the pump when the motor of the
pump becomes over heated, for example by a locked rotor due to ice
formation in the water cooling passage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention may be more clearly understood from the
following detailed description by reference to the drawing in
which:
[0017] FIG. 1 is a plan view of a combined centrifugal water pump
and electrically driven motor in accordance with this
invention;
[0018] FIG. 2 is a pump end elevational view of the pump/motor
combination of FIG. 1; and
[0019] FIG. 3 is an enlarged diametrical sectional view of the
pump/motor combination of FIGS. 1 and 2 taken along line 3-3 of
FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] FIG. 1 is a plan view of a combined centrifugal water pump
and electrically driven motor 10 in accordance with this invention.
The pump portion includes a volute body 12, including a water inlet
member 14. A discharge tube 16 is fastened to volute body 12.
Secured to the volute body 12 is a motor housing 18, which
incorporates cooling fins 20. Attached to the motor housing 18 are
mounting brackets 22 and 24, which include top and bottom portions
secured together by bolts 25, which are best seen in FIG. 2. An end
cap 26 of FIGS. 1 and 2 closes one end of housing 18 and
incorporates a tubular portion 28 carrying a feed through assembly
30 for electrical wires 31 connected to the motor.
[0021] Details of the combined centrifugal water pump and
electrically driven motor 10 will become apparent through
consideration of FIG. 3, which is a sectional view taken along line
3-3 of FIG. 2. Carried within the volute 12 is an impeller 32
secured to a hollow rotor shaft 34 by means of a screw 36 having an
axial bore 37. At its left end, shaft 34 is supported on a carbon
bearing 38 positioned between a thrust plate 40 and a washer 42. A
drive pin 44 passes through the shaft 34 and extends into a chamber
formed by thrust plate 40, which has an internal diameter slightly
larger than the diameter of rotor shaft 34. The function of drive
pin 44 is to provide a positive drive for the thrust plate 40.
[0022] Carried on the rotor shaft 34 are a plurality of annular
steel washers or laminations 73, which, along with rotor end plates
47 and 49, collectively, constitute the rotor 46 of the electric
motor. Supporting the opposite end of the rotor shaft 34 is another
carbon bearing 48, which is carried in a cylindrical sleeve 50.
Movable within a smaller diameter bore of sleeve 50 is a piston 54
which is urged toward the left by a plurality of wave leaf
compression springs 56 contained within sleeve 50 by means of a
spacer 58 and a retaining ring 74. The piston moving in its bore
provides an expansion chamber in case the water within the motor
freezes. This avoids any freezing damage to the motor or pump.
[0023] Surrounding rotor 46 and secured within housing 18 are a
plurality of annular laminations 60 forming part of the stator of
the electric motor. Stator windings 62 are wound around both sides
of the laminations and are connected to the electrical conductor
feed through assembly 30. Positioned in the housing 18 between the
stator windings 62 and the rotor 46 is an insulated backing sleeve
64. The stator laminations 60, windings 62 and rotor 46 laminations
are separated by thin, stainless steel sleeves 66 and 68, which
leave a generally tubular passageway between their adjacent
surfaces, namely, the outer surface of 68 and inner surface of
66.
[0024] One pair of leads from the feed-through assembly 30
terminates at a thermally operated switch TS, which is bonded to
the stator windings 62. The switch TS is normally closed but opens
to interrupt power to the motor 10 if the stator winding increases
in temperature above normal as in the case of an attempted start
where ice locks the rotor into static operation. A suitable thermal
switch is a model 4 BTL-2 bimetallic switch of Texas Instruments of
Attelboro, Mass.
[0025] In operation, with the inlet member 14 connected to a source
of potable water under a relatively low pressure, such as a gravity
flow from only a few feet of head, energizing of the motor will
turn rotor 46, rotating rotor shaft 34 and impeller 32 drawing
water into the volute body 12. The greatest part of this water
enters volute chamber 70 and is then discharged from discharge tube
16.
[0026] Volute chamber 70 has water at the pump discharge pressure,
which is somewhat higher than the inlet pressure to the impeller
and some of this higher pressure water flows into a chamber 72
between the impeller 32 and the washer 42. Because of clearance
between washer 42 and the volute housing 12, water will flow
between washer 42 and carbon bearing 38, between carbon bearing 38
and the surface of rotor shaft 34, between carbon bearing 38 and
thrust plate 40, and between the sleeves 66 and 68. Water flowing
from between sleeves 66 and 68 then enters a chamber 69 between
rotor endplate 62 and carbon bearing 48, passes between carbon
bearing 48 and the surface of rotor 34, flows around the right end
of rotor shaft 34, through the center of rotor shaft 34, through
bore 37 in screw 36, and back into the inlet to the impeller 32.
This flow path provides both cooling and lubrication between the
rotating and stationary parts of the electric motor and affords no
occasion to cause contamination of the potable water flowing
through the motor. The steel motor laminations are protected from
contact with the water running between sleeves 66 and 68, which do
allow heat to flow from the laminations into the water.
[0027] The above-described embodiments of the present invention are
merely descriptive of its principles and are not to be considered
limiting. The scope of the present invention instead shall be
determined from the scope of the following claims including their
equivalents.
* * * * *