U.S. patent application number 12/255034 was filed with the patent office on 2009-07-30 for electrically powered pump.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Kazunori SUZUKI.
Application Number | 20090191074 12/255034 |
Document ID | / |
Family ID | 40899430 |
Filed Date | 2009-07-30 |
United States Patent
Application |
20090191074 |
Kind Code |
A1 |
SUZUKI; Kazunori |
July 30, 2009 |
ELECTRICALLY POWERED PUMP
Abstract
An electrically powered pump includes a pump arrangement that
pumps a liquid, and an electric motor arrangement that has a stator
and a rotor that are installed on a passage through which the
liquid pumped by the pump arrangement flows. At least one of the
stator and the rotor has a winding wire that generates a magnetic
field when it is energized to rotate the rotor with respect to the
stator to drive the pump arrangement. The winding wire has a
conductive body through which an electric current passes and an
insulation body that insulates the conductive body. The conductive
body is made of a material predominantly composed of carbon.
Thereby, the liquid pumped by a pump arrangement is prevented from
corroding the winding wire.
Inventors: |
SUZUKI; Kazunori;
(Nagoya-city, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
40899430 |
Appl. No.: |
12/255034 |
Filed: |
October 21, 2008 |
Current U.S.
Class: |
417/423.7 ;
60/282 |
Current CPC
Class: |
F01N 2610/1433 20130101;
Y02A 50/2325 20180101; F01N 3/2066 20130101; F04D 5/002 20130101;
F01N 2610/1406 20130101; H02K 3/44 20130101; H02K 3/02 20130101;
F04D 13/06 20130101; F01N 2610/02 20130101; Y02A 50/20 20180101;
H02K 5/12 20130101 |
Class at
Publication: |
417/423.7 ;
60/282 |
International
Class: |
F04D 13/06 20060101
F04D013/06; F01N 3/10 20060101 F01N003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 29, 2008 |
JP |
2008-17085 |
Claims
1. An electrically powered pump comprising: a pump arrangement that
pumps a liquid; and an electric motor arrangement that has a stator
and a rotor that are installed on a passage through which the
liquid pumped by the pump arrangement flows, wherein: at least one
of the stator and the rotor has a winding wire that generates a
magnetic field when it is energized to rotate the rotor with
respect to the stator to drive the pump arrangement; the winding
wire has a conductive body through which an electric current passes
and an insulation body that insulates the conductive body; and the
conductive body is made of a material predominantly composed of
carbon.
2. The electrically powered pump according to claim 1, wherein the
conductive body is a strand that is formed by spinning carbon
nanotubes.
3. The electrically powered pump according to claim 1, wherein the
conductive body is a strand that is formed by binding carbon
nanotubes by a binder.
4. The electrically powered pump according to claim 1, wherein: the
conductive body is a plurality of strands that is twisted together;
and the plurality of strands is made of a material predominantly
composed of carbon.
5. The electrically powered pump according to claim 1, wherein: the
pump is adapted to be installed in an internal combustion engine of
an vehicle; and the liquid pumped by the pump arrangement is a
reducing agent that reduces a nitrogen oxide contained in an
exhaust gas of the internal combustion engine.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and incorporates herein by
reference Japanese Patent Application No. 2008-017085 filed on Jan.
29, 2008.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an electrically powered
pump that has an electric motor arrangement for driving a pump
arrangement.
[0004] 2. Description of Related Art
[0005] In recent years, selective reduction (SCR: Selective
Catalytic Reduction) type urea SCR system is under development, and
partly put into actual use. The SCR system is installed in an
internal combustion engine (especially diesel engine) of a vehicle,
etc., to reduce NOx (nitrogen oxides) in exhaust gas.
[0006] In the urea SCR system, a selective reduction type NOx
cleaning catalyst (SCR catalyst) is installed in an exhaust pipe of
an internal combustion engine, and a urea water addition valve,
which adds urea water (urea water solution) as a reducing agent to
the exhaust gas in the exhaust pipe, is installed on an upstream
side of the NOx cleaning catalyst. In this system, the urea water
addition valve adds the urea water to the exhaust gas in the
exhaust pipe, and the urea water is supplied to the NOx cleaning
catalyst together with the exhaust gas. Then, the exhaust gas is
cleaned up by NOx reduction reaction on this NOx cleaning catalyst.
In the reduction of NOx, the urea water is hydrolyzed by a heat of
the exhaust gas to generate ammonia (NH.sub.3), and NOx is
selectively reduced in the NOx cleaning catalyst by the ammonia
even in an atmosphere in which oxygen concentration is high, to
perform a cleaning of the exhaust gas (see JP2004-510093T
corresponding to US2004/0115074A1, etc.).
[0007] This kind of urea SCR system requires a urea water pump that
pumps the urea water stored in a tank to the urea water addition
valve. The inventor of the present invention tried to use a
conventional general electrically powered pump as this urea water
pump, This electrically powered pump is a pump that has a pump
arrangement for pumping a liquid, and an electric motor arrangement
for driving the pump arrangement.
[0008] However, when the conventional electrically powered pump was
used as the urea water pump as it is, corrosion of winding wires,
which are described below, became a problem.
[0009] The above-mentioned winding wires are wired on at least one
of a stator and a rotor that constitute the pump arrangement to
generate a magnetic field when it is energized. Conventional
general winding wire has a copper conductive body and an insulation
body that insulates the conductive body. Moreover, the conventional
electrically powered pump has a construction in which a resin
(covering resin) covers an entire body of the stator or the rotor
to prevent the wiring wire from corroding by keeping the wiring
wire away from the liquid pumped by the pump arrangement. The
inventor found that it is further required to take measures against
corrosion of the winding wires, since urea water easily permeates
the above-mentioned covering resin and the insulator compared with
mere water, and easily corrodes the copper conductive body.
[0010] In addition, such problems as the corrosion of the winding
wires are caused not only by urea water but by other liquids except
water. For example, alcohol, biofuel, etc. are used in some cases
as fuel of an internal combustion engine of a vehicle in recent
years. Also in an electrically powered pump that pumps such fuel to
fuel injection valves, there is a concern that the fuel may
permeate the covering resin and the insulator to corrode the copper
conductive body.
SUMMARY OF THE INVENTION
[0011] The present invention is made in view of the above-mentioned
problem.
[0012] Thus, it is an objective of the present invention to provide
an electrically powered pump that has an electric motor arrangement
for driving a pump arrangement, in which a liquid pumped by a pump
arrangement is prevented from corroding a winding wire.
[0013] To achieve the objective of the present invention, there is
provided an electrically powered pump. The electrically powered
pump includes a pump arrangement that pumps a liquid, and an
electric motor arrangement that has a stator and a rotor that are
installed on a passage through which the liquid pumped by the pump
arrangement flows. At least one of the stator and the rotor has a
winding wire that generates a magnetic field when it is energized
to rotate the rotor with respect to the stator to drive the pump
arrangement. The winding wire has a conductive body through which
an electric current passes and an insulation body that insulates
the conductive body. The conductive body is made of a material
predominantly composed of carbon.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention, together with additional objectives, features
and advantages thereof, will be best understood from the following
description, the appended claims and the accompanying drawings in
which:
[0015] FIG. 1 is a schematic diagram showing an entire construction
of a urea SCR system in which a urea water pump (electrically
powered pump) according to one embodiment of the present invention
is incorporated;
[0016] FIG. 2 is a cross sectional view showing a construction of
the urea water pump shown in FIG. 1 in detail;
[0017] FIG. 3A is a cross-sectional view taken along a line
IIIA-IIIA in FIG. 2;
[0018] FIG. 3B is an enlarged view of FIG. 3A;
[0019] FIG. 4 is a fragmentary perspective view showing a stator
and an insulating resin body that molds the stator therein, which
are shown in FIGS. 3A, 3B;
[0020] FIG. 5 is a perspective view showing an end portion of a
wiring showing the end of a winding wire shown in FIG. 4; and
[0021] FIG. 6 is a cross-sectional view of the winding wire shown
in FIG. 5.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] An electrically powered pump according to one embodiment of
the present invention will be described hereafter, with reference
to the accompanying drawings.
[0023] The electrically powered pump according to the present
embodiment is applied to a urea water pump that pumps urea water
solution (hereafter referred to just as urea water) that contains
urea as a reducing agent. The urea water discharged from the urea
water pump is pressurized and pumped to an addition valve. The
addition valve is so installed as to inject the urea water in an
exhaust gas flow in an exhaust passage of a diesel engine
(hereafter referred to as engine), which is an internal combustion
engine.
[0024] FIG. 1 schematically shows an entire construction of a urea
SCR system in which the urea water pump (electrically powered pump)
according to the present embodiment is incorporated. FIG. 1 depicts
an exhaust emission control device in which exhaust gas discharged
from the engine of a vehicle (not shown) is cleaned up. Components
of the exhaust emission control system are roughly classified into
an arrangement of an exhaust gas system, an arrangement of a urea
water supply system, and an arrangement of a control system.
[0025] The arrangement of the exhaust gas system includes a DPF 1
(Diesel Particulate Filter), an exhaust pipe 2 (exhaust passage on
an upstream side of a catalyst), the catalyst 3, and an exhaust
pipe 4 (exhaust passage on a downstream side of the catalyst) that
are arranged in this order from an upstream side of the exhaust gas
flow. The DPF 1 is a continuous regeneration type PM removing
filter that collects PM (Particulate Matters) in exhaust gas. The
DPF 1 can be continuously used by repeatedly burning and removing
the collected PM by post injections subsequent to main fuel
injections, which are equivalent to regeneration processes of PM
removing filters, for example. The DPF 1 supports a platinum base
oxidation catalyst (not shown) to remove HC and CO together with
soluble organic fraction (SOF) that is one ingredient of PM.
[0026] The catalyst 3 is a part that promotes NOx reduction
reaction to clean up the exhaust gas. The catalyst 3 reduces NOx in
the exhaust gas by promoting reactions as follows, for example:
4NO+4NH.sub.3+O.sub.2.fwdarw.4N.sub.2+6H.sub.2O (Chemical formula
1)
6NO.sub.2+8NH.sub.3.fwdarw.7N.sub.2+12H.sub.2O (Chemical formula
2)
NO+NO.sub.2+2NH.sub.3.fwdarw.2N.sub.2+3H.sub.2O (Chemical formula
3)
[0027] A water solution (hereafter referred to as urea water) that
contains ammonia (NH.sub.3), which serves as a reducing agent for
NOx in these reactions, is mixed with the exhaust gas and supplied
to the catalyst 3. Specifically, the urea water is injected by the
addition valve that is described later, and is supplied to the
exhaust gas flowing through the exhaust pipe 2 on the upstream side
of the catalyst 3.
[0028] The arrangement of the urea water supply system includes a
urea water supply unit 5, the addition valve 6, a distribution pipe
7, etc. The urea water supply unit 5 has a urea water tank 8, the
urea water pump 9 (electrically powered pump), etc. The urea water
tank 8 includes an airtight container and a supplying cap. The urea
water in a predetermined concentration is stored in the urea water
tank 8. In the present embodiment, the urea water pump 9 is an
in-tank type one and installed in the urea water tank 8.
[0029] The urea water pump 9 is an electromotive pump that is
rotationally driven by a drive signal sent from ECU (Electronic
Control Unit) 10 that serves as a controller. When the urea water
pump 9 is driven, the urea water in the urea water tank 8 is sucked
into the urea water pump 9 via a strainer 9a and a filter 9b, and
pressurized. Then, a regulator 9c adjusts a discharge pressure of
the urea water pump 9, and the urea water is pumped to the addition
valve 6 via the distribution pipe 7. The urea water pump 9, the
filter 9b, the regulator 9c, etc. are accommodated in a unit case
9d to be unitized. When a supply pressure of the urea water pump 9
exceeds a regulation pressure of the regulator 9c, the urea water
in the distribution pipe 7 is returned to the urea water tank 8 by
the regulator 9c.
[0030] An injection port is formed at a tip of the addition valve
6. When an electromagnetic actuator performs a valve-opening
operation of a needle valve that opens and closes the injection
port, the urea water, which was supplied to the addition valve 6 by
an operation of the urea water pump 9, is injected into the exhaust
pipe 2 in an atomized form. When the urea water is supplied and
added to the exhaust gas in this manner, the urea water is supplied
to the SCR catalyst 3 together with the exhaust gas in the exhaust
pipe 2. The urea SCR system is so configured as to clean up the
exhaust gas by performing NOx reduction reaction at the SCR
catalyst 3.
[0031] In the reduction of NOx, the urea water is hydrolyzed by a
heat of the exhaust gas in accordance with a reaction as follows,
for example:
(NH.sub.2).sub.2CO+H.sub.2O.fwdarw.2NH.sub.3+CO.sub.2 (Chemical
formula 4)
[0032] Thereby, ammonia (NH.sub.3) is generated, and this ammonia
is added to NOx in the exhaust gas, which is selectively adsorbed
to the SCR catalyst 3. Then, reduction reactions are performed by
the ammonia in accordance with the above-mentioned chemical
formulas 1 to 3, to reduce the NOx to clean up the exhaust gas.
[0033] A construction of a discrete assembly of the urea water pump
9 is described below in detail, with reference to FIGS. 2 to 4.
[0034] As shown in FIG. 2, the urea water pump 9 has a pump
arrangement 18 that pumps the urea water, and an electric motor
arrangement 19 that drives the pump arrangement 18. The pump
arrangement 18 is a peripheral pump that has a pump case and an
impeller 22. The pump case includes two components of the upper
case 20 and a lower case 21 that are jointed to each other. A space
that serves as a pump chamber is formed radially inside of mating
faces of the upper case 20 and the lower case 21. The impeller 22
is rotatably installed in the pump house. When the impeller 22
rotates, the urea water stored in the urea water tank 8 is sucked
into a suction port 24 that is formed in the lower case 21,
pressured up in the pump chamber, and pumped to the electric motor
arrangement 19, which is described later.
[0035] It is desirable that a component that has a portion on which
urea water circulates is made of a material having corrosion
resistance and oxidation resistance against urea water, among
components of the urea water pumps 9. The upper case 20 and the
lower case 21 are made of metal. In view of corrosion resistance
and oxidation resistance, the upper case 20 and the lower case 21
are desirably made of JIS SUS304 corresponding to AISI 304, which
is an austenitic stainless steel, a passivation coating
regenerating material. Further, the impeller 22 is made of resin
(phenol resin, for example).
[0036] The electric motor arrangement 19 is a brushless motor that
has a stator 25, a rotor 26, etc., and functions to generate a
driving force for pumping the urea water when it is energized. As
shown in FIG. 3A that is a cross-sectional view taken along a line
IIIA-IIIA in FIG. 2, the stator 25 includes six split cores 25a
(core parts) that are arranged in a circular manner. Each split
core 25a is composed of magnetic steel plates, on which an
insulating coating is applied, that are integrally laminated in a
direction along a revolving shaft (in a vertical direction in FIG.
2). A bobbin 28 that is made of an insulating material such as
resin is attached to each split core 25a (see FIGS. 2 and 3B).
[0037] Winding wires 29 are series-wound (or shunt-wound) on an
outer circumference of the bobbin 28 of each split core 25a. The
winding wires 29 are electrically connected with terminals 43 on an
end cover 37 side as shown in FIG. 2. The winding wires 29 are
classified into three kinds of U phase, V phase and W phase ones. A
switching by the ECU 10 controls a current flow from the terminals
43 to the winding wires 29 of respective phases. Thereby, magnetic
poles are generated on the winding wires 29 of the respective
phases. Therefore, a clearance between an inner circumferential
surface of the stator 25 and an outer circumferential surface of
the rotor 26 serves as a circulation passage 38 as mentioned above,
and as a gap between the stator 25 and the rotor 26 on a magnetic
circuit.
[0038] A permanent magnet 31 is a plastic magnet that is formed
into a cylindrical shape by kneading thermoplastic resin material
such as PPS with magnetic powder. The permanent magnet 31 is formed
directly on a circumference of the revolving shaft 27 by injection
molding, etc. As shown in FIG. 3A, the permanent magnet 31 forms
eight magnetic pole portions that are arranged around the
circumference of the revolving shaft 27. These magnetic pole
portions are magnetized to form different magnetic poles in its
peripheral portions by turns around the circumference of the
revolving shaft 27, to face the stator 25.
[0039] FIG. 4 is a fragmentary perspective view showing the stator
25 and an insulating resin body 45 that molds the stator 25
therein. As shown in FIG. 4, the six split cores 25a, the winding
wires 29 of respective phases and the terminals 43 are resin molded
in the insulating resin body 45 to be united. This insulating resin
body 45 covers also the inner circumferential surface of the split
cores 25a, The permanent magnet 31 is also covered with an
insulating resin body 31a. That is, to be exact, the
above-mentioned circulation passage 38 is formed between an inner
circumferential wall portion 45a of the insulating resin body 45
and an outer circumferential wall portion 31a (see FIG. 3B) of the
insulating resin body that covers the permanent magnet 31! A
referential numeral 45b in FIG. 3A denotes an outer circumferential
wall portion of the insulating resin body 45.
[0040] A housing 36 serves as a housing of both of the pump
arrangement 18 and the electric motor arrangement 19. The housing
36 is made of metal. Both axial ends of the housing 36 are
respectively crimped onto the lower case 21 and onto the end cover
37. The upper case 20 butts against a step portion 36a of the
housing 36 in an axial direction of the housing 36. Thereby, an
axial position of the upper case 20 is determined. A bearing
portion 32 is fixed to a radially central portion of the upper case
20 by press fitting. The lower case 21 is fixed to one end of the
housing 36 by crimping. An axial force produced by the crimping
provides a surface pressure that pushes the upper case 20 and the
steps portion 36a onto each other, and the lower case 21 and the
upper case 20 onto each other in the axial direction, to seal the
urea water.
[0041] The urea water pumped to the electric motor arrangement 19
side is sent into the circulation passage 38 between the stator 25
and the rotor 26 (see FIGS. 2 and 3A), and then into a discharge
passage 39, and is further supplied from a discharge port 40 to the
addition valve 6 side. The discharge port 40 of the discharge
passage 39, which is formed in the end cover 37 to open to an
outside, is arranged to be eccentric with respect to a bearing
portion 33.
[0042] The above-mentioned insulating resin body 45 is integrally
formed with the end cover 37 that covers a counter-pump arrangement
18 side end portion of the stator 25. The bearing portion 33 that
supports the revolving shaft 27, a base portion of the terminals 43
and the discharge port 40 are united by the insulating resin body
45, to form the end cover 37.
[0043] A check valve 47 and a spring 48 are accommodated in the
discharge port 40 that is formed in the end cover 37. When a
pressure of the urea water that is pressured up in the pump
arrangement 18 reaches a predetermined value, the check valve 47
lifts up against a biasing force of the spring 48, to discharge the
urea water from the discharge port 40 to the addition valve 6 side.
The check valve 47 is installed to prevent a back-flow of the urea
water that is discharged from the urea water pump 9.
[0044] Next, a construction and a material of the winding wire 29,
which are the essence of the present invention, are described
below, with reference to FIGS. 5 and 6
[0045] The same winding wire is used for the respective winding
wires 29 of U phase, V phase and W phase. This winding wire 29 has
a conductive body 29a through which current passes, and an
insulation body 29b that covers the conductive body 29a. FIG. 5 is
a perspective view showing an end portion of the winding wire 29.
In the end portion of the winding wire 29, a tip end of the
conductive body 29a is exposed out of the insulation body 29b. This
exposed tip end is connected with the terminals 43.
[0046] As shown in FIG. 6 that is a cross-sectional view of the
winding wire 29, two or more strands 29c are twisted together into
a shape of a wire, to form the conductive body 29a. The strand 29c
is made of a material that is predominantly composed of carbon.
Specifically, the strand 29c is formed by spinning carbon nanotubes
only, or by binding carbon nanotubes by a binder. The strand 29c
can be processed by manufacturing methods disclosed in
JP2007-126318A, JP2007-161512A, etc.
[0047] It is desirable that the terminal 43 is also made of a
material that is predominantly composed of carbon. It is desirable
that a composition of the terminal 43 is substantially the same as
the composition of the above-mentioned strand 29c (a composition of
carbon nanotubes or carbon fibers, for example). A material of the
insulation body 29b is resin or rubber.
[0048] The urea water pump 9 is an electrically powered pump, and
there is an apprehension that the urea water corrodes electric
parts and other kinds of parts in the electric motor arrangement 19
since the urea water pumped in the pump arrangement 18 circulates
through the electric motor arrangement 19. In the present
embodiment, as a measure against this apprehension, the insulating
resin body 45, which molds the stator 25 therein, has an inner
circumferential wall portion 45a, and the insulating resin body,
which molds the permanent magnet 31 therein, has the inner
circumferential wall portion 31a.
[0049] Thereby, in a formation of the circulation passage 38 of
urea water in the clearance between the inner circumferential
surface of the stator 25 and the outer circumferential surface of
the rotor 26, the inner circumferential wall portion 45a covers the
electric parts of the stator 25 such as the split cores 25a and the
winding wires 29, to prevent the electric parts from being directly
exposed to the urea water in the circulation passage 38. Further,
the outer circumferential wall portion 31a covers the parts of the
rotor 26 such as the permanent magnet 31, to prevent the parts from
being directly exposed to the urea water in the circulation passage
38. Therefore, it is possible to prevent the split cores 25a, the
winding wires 29 and the permanent magnet 31 from being corroded by
the urea water.
[0050] However, the inventor found that the urea water swells the
inner circumferential wall portion 45a and the outer
circumferential wall portion 31a, which are made of resin, and that
the urea water can permeate into the walls portions 45a and 31a due
to this swelling. Further, copper is generally used as a
conventional material of the conductive body 29a of the winding
wire 29, and the inventor found that it is necessary to raise
corrosion resistance of the winding wire 29, particularly the
corrosion resistance of the conductive body 29a.
[0051] In view of this point, in the present embodiment, the
conductive body 29a is made of a material that is predominantly
composed of carbon. The carbon has an electrical resistance that is
approximately equal to an electrical resistance of copper, and has
a corrosion resistance against ammonia (NH.sub.3) that is higher
than a corrosion resistance of copper. Further, since the urea
water pump 9 is installed in an engine room of a vehicle, an
environmental temperature of the urea water pump 9 is high, and a
heat resistance of the winding wire 29 must be high. In this
regard, a heat resistance of carbon is excellent with respect to a
heat resistance of copper. Therefore, according to the present
embodiment in which carbon is applied to the conductive body 29a,
the corrosion resistance of the winding wire 29 against the urea
water is improved, without raising electric resistance and without
reducing heat resistance, with respect to a winding wire having a
conventional copper conductive body.
[0052] Further, in the present embodiment, two or more strands 29c
are twisted together into a shape of a wire, to form the conductive
body 29a. Thereby, a strength of the winding wire 29 can be
improved by raising a strength of the conductive body 29a. in a
manufacturing process in which the winding wires 29 are wound on
the split cores 25a, the winding wires 29 are wound under a
tension, so that the winding wire 29 must have a tensile strength
that can bear the above-mentioned tension. Therefore, the
manufacturing process of the stator 25 makes use of the
above-mentioned advantage that the strength of the winding wire 29
is improved.
[0053] Furthermore, in the present embodiment, the strands 29c of
the conductive body 29a are composed of carbon nanotubes, to form
the conductive body 29a having the strands 29c that is made of a
material that is predominantly composed of carbon, Thereby, the
conductive body 29a has a high conductivity and a high
strength.
[0054] Furthermore, if the conductive body 29a is composed of the
strands 29c that are formed by spinning carbon nanotubes only, the
conductive body 29a has a higher conductivity and a higher strength
than those of the conductive wire 29a that is composed of the
strands 29c that are formed by binding carbon nanotubes by
binders.
Other Embodiments
[0055] The above-described embodiments may be modified and put into
practice as follows. Further, the present invention is not limited
to the content of the above-described embodiment, It is possible to
combine respective distinctive constructions of the above-described
embodiment arbitrarily.
[0056] (1) In the above-described embodiment, carbon nanotubes are
used as the material of the strands 29c that form the conductive
body 29a, In this regard, carbon fibers can be used instead of the
carbon nanotubes. That is, the strand 29c can be formed by spinning
carbon fibers only. The strand 29c can also be formed by binding
carbon fibers by binders.
[0057] (2) The strand 29c that is composed of carbon fibers or
carbon nanotubes may be so formed as to extend from one end to the
other end of the winding wire 29 without having connecting portions
The strand 29c may also be formed by connecting two or more strands
on a middle of the winding wire 29 between its one end and the
other end.
[0058] (3) In the above-described embodiment, the electrically
powered pump according to the present invention is applied to a
urea water pump. However, the present invention is not limited to
such a urea water pump, For example, the electrically powered pump
according to the present invention may be applied to a fuel pump
that is mounted on a vehicle having an internal combustion engine
to pump a fuel that was reserved in a fuel tank to fuel injection
valves that injects the fuel into combustion chambers or into an
intake pipe of the internal combustion engine. Further, in an
internal combustion engine in which hydrocarbon (HC) is added to
exhaust gas as a reducing agent instead of adding urea water as a
reducing agent, the electrically powered pump according to the
present invention may be applied to a pump that pumps the
hydrocarbon to an addition valve.
[0059] (4) In the above-described embodiments, the present
invention is applied to the electrically powered pump 9 in which
the stator 25 has the winding wires 29 and the conductive bodies
29a of the winding wires 29 on the stator 25 side are made of
carbon. Alternatively, the present invention may also be applied to
an electrically powered pump in which a rotor has winding wires and
conductive bodies of the winding wires on the rotor side are made
of carbon.
[0060] Additional advantages and modifications will readily occur
to those skilled in the art. The invention in its broader terms is
therefore not limited to the specific details, representative
apparatus, and illustrative examples shown and described.
* * * * *