U.S. patent application number 11/546914 was filed with the patent office on 2007-04-19 for brushless motor and fluid pump having the same.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Kiyoshi Nagata, Shinji Sumiya.
Application Number | 20070086905 11/546914 |
Document ID | / |
Family ID | 37896581 |
Filed Date | 2007-04-19 |
United States Patent
Application |
20070086905 |
Kind Code |
A1 |
Nagata; Kiyoshi ; et
al. |
April 19, 2007 |
Brushless motor and fluid pump having the same
Abstract
A fuel pump includes a stator core that has teeth being
circumferentially arranged. Coils are formed by concentrically
winding a wire around each of the teeth. The coils
circumferentially generate magnetic poles in inner circumferential
peripheries of the teeth when being supplied with electricity. The
magnetic poles being switched by controlling electricity supplied
to the plurality of coils. A rotator has an outer circumferential
periphery opposed to the inner circumferential peripheries. The
outer circumferential periphery defines magnetic poles different
from each other with respect to a rotative direction thereof. A
pump portion that has a rotor member rotated by the rotator for
pumping fuel. An electrically insulative resin material is charged
between the teeth, which are circumferentially adjacent to each
other, thereby being molded such that the electrically insulative
resin material covers the plurality of coils.
Inventors: |
Nagata; Kiyoshi;
(Nagoya-city, JP) ; Sumiya; Shinji; (Kariya-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: |
37896581 |
Appl. No.: |
11/546914 |
Filed: |
October 13, 2006 |
Current U.S.
Class: |
417/423.3 |
Current CPC
Class: |
F02M 37/048 20130101;
H02K 5/12 20130101; H02K 3/44 20130101; H02K 5/08 20130101 |
Class at
Publication: |
417/423.3 |
International
Class: |
F04B 17/00 20060101
F04B017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 18, 2005 |
JP |
2005-302698 |
Claims
1. A fluid pump comprising: a stator core that includes a plurality
of teeth, which is circumferentially arranged; a plurality of coils
each being formed by concentrically winding a wire around an outer
circumferential periphery of each of the plurality of teeth, the
plurality of coils circumferentially generating magnetic poles in
inner circumferential peripheries of the plurality of teeth when
being supplied with electricity, the magnetic poles being switched
by controlling electricity supplied to the plurality of coils; a
rotator that is rotatable around the inner circumferential
peripheries of the plurality of teeth, the rotator having an outer
circumferential periphery opposed to the inner circumferential
peripheries of the plurality of teeth, the outer circumferential
periphery defining magnetic poles different from each other with
respect to a rotative direction of the rotator; a pump portion that
has a rotor member, the rotator rotating the rotor member for
pumping fluid; and an electrically insulative resin material that
is charged between the plurality of teeth, which are
circumferentially adjacent to each other, wherein the electrically
insulative resin material is molded such that the electrically
insulative resin material covers the plurality of coils.
2. The fluid pump according to claim 1, wherein the plurality of
teeth is separate from each other.
3. The fluid pump according to claim 1, wherein the electrically
insulative resin material is integrally molded with a cover that
covers an end of the stator core on an opposite side of the pump
portion with respect to the stator core.
4. The fluid pump according to claim 3, further comprising: a valve
member that restricts fluid, which is pumped using the pump
portion, from causing reverse flow; and a stopper that restricts a
lift position of the valve member, wherein the cover accommodates
the valve member and the stopper.
5. The fluid pump according to claim 1, further comprising: a
plurality of terminals that is insert-molded in the electrically
insulative resin material, the plurality of terminals electrically
connecting with the plurality of coils; and a slant restricting
member that restricts the plurality of terminals from being slanted
when the electrically insulative resin material is molded.
6. The fluid pump according to claim 1, wherein the stator core
includes a toroidal core that circumferentially surrounds outer
circumferential peripheries of the plurality of teeth, and each of
the plurality of teeth engages with the toroidal core.
7. A brushless motor that is at least partially submerged in fluid,
the brushless motor comprising: a stator core that includes a
plurality of teeth, which is circumferentially arranged; a
plurality of coils each being formed by concentrically winding a
wire around an outer circumferential periphery of each of the
plurality of teeth, the plurality of coils circumferentially
generating magnetic poles in inner circumferential peripheries of
the plurality of teeth when being supplied with electricity, the
magnetic poles being switched by controlling electricity supplied
to the plurality of coils; a rotator that is rotatable around the
inner circumferential peripheries of the plurality of teeth, the
rotator having an outer circumferential periphery opposed to the
inner circumferential peripheries of the plurality of teeth, the
outer circumferential periphery defining magnetic poles different
from each other with respect to a rotative direction of the
rotator; and an electrically insulative resin material that is
charged between the plurality of teeth, which are circumferentially
adjacent to each other, wherein the electrically insulative resin
material is molded such that the electrically insulative resin
material covers the plurality of coils, and the electrically
insulative resin material insulates the plurality of coils from the
fluid.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and incorporates herein by
reference Japanese Patent Application No. 2005-302698 filed on Oct.
18, 2005.
FIELD OF THE INVENTION
[0002] The present invention relates to a brushless motor and a
fuel pump having the brushless motor.
BACKGROUND OF THE INVENTION
[0003] For example, according to JP-A-5-340345, a fuel pump
includes a brushless motor as a driving source. In general, a motor
(brush motor) having a brush causes a loss such as slide resistance
between a commutator and a brush, electric resistance between the
commutator and the brush, and fluid resistance caused in grooves,
via which the commutator is divided into segments. By contrast, a
brushless motor may not cause the above losses arising the brush
motor. Therefore, a brushless motor is higher than a brush motor in
motor efficiency, so that a fuel pump having a brushless motor is
enhanced in pump efficiency. Here, the pump efficiency is a ratio
of an amount of work produced by the fuel pump relative to
electricity supplied to the fuel pump. The amount of work produced
by the fuel pump can be calculated by multiplying fuel discharge
pressure by a fuel discharge amount.
[0004] When the amount of work is constant, as the efficiency of
the fuel pump increases, a motor portion can be downsized, so that
the fuel pump can be downsized. A fuel pump including a brushless
motor may be applied to a small vehicle such as a motor cycle.
[0005] A fuel pump may be downsized by reducing a space occupied by
coils. In addition, a coil in a fuel pump needs to be protected
from corrosion due to exposure to fuel such as debased fuel or low
quality fuel is used.
[0006] The JP-A-5-340345 does not disclose reduction of the space
occupied by the coils in the brushless motor applied to the fuel
pump. In addition, in JP-A-5-340345, a case is provided for
accommodating the stator, which includes the coils and the stator
core, for protecting the stator from corrosion. The components
constructing the case are welded for tightly sealing. Accordingly,
in this structure manufacturing work is necessary for welding the
case.
SUMMARY OF THE INVENTION
[0007] In view of the foregoing and other problems, it is an object
of the present invention to produce a brushless motor that includes
coils, which can be protected by a simple structure. It is another
object of the present invention to produce a fuel pump having the
brushless motor.
[0008] According to one aspect of the present invention, a fluid
pump includes a stator core that includes a plurality of teeth,
which is circumferentially arranged. The fluid pump further
includes a plurality of coils each being formed by concentrically
winding a wire around an outer circumferential periphery of each of
the plurality of teeth. The plurality of coils circumferentially
generates magnetic poles in inner circumferential peripheries of
the plurality of teeth when being supplied with electricity. The
magnetic poles are switched by controlling electricity supplied to
the plurality of coils. The fluid pump further includes a rotator
that is rotatable around the inner circumferential peripheries of
the plurality of teeth, the rotator having an outer circumferential
periphery opposed to the inner circumferential peripheries of the
plurality of teeth. The outer circumferential periphery defines
magnetic poles different from each other with respect to a rotative
direction of the rotator. The fluid pump further includes a pump
portion that has a rotor member, the rotator rotating the rotor
member for pumping fluid. The fluid pump further includes an
electrically insulative resin material that is charged between the
plurality of teeth, which are circumferentially adjacent to each
other. The electrically insulative resin material is molded such
that the electrically insulative resin material covers the
plurality of coils.
[0009] According to another aspect of the present invention, a
brushless motor is at least partially submerged in fluid. The
brushless motor includes a stator core that includes a plurality of
teeth, which is circumferentially arranged. The brushless motor
further includes a plurality of coils each being formed by
concentrically winding a wire around an outer circumferential
periphery of each of the plurality of teeth. The plurality of coils
circumferentially generates magnetic poles in inner circumferential
peripheries of the plurality of teeth when being supplied with
electricity, the magnetic poles being switched by controlling
electricity supplied to the plurality of coils. The brushless motor
further includes a rotator that is rotatable around the inner
circumferential peripheries of the plurality of teeth, the rotator
having an outer circumferential periphery opposed to the inner
circumferential peripheries of the plurality of teeth. The outer
circumferential periphery defines magnetic poles different from
each other with respect to a rotative direction of the rotator. The
brushless motor further includes an electrically insulative resin
material that is charged between the plurality of teeth, which are
circumferentially adjacent to each other. The electrically
insulative resin material is molded such that the electrically
insulative resin material covers the plurality of coils. The
electrically insulative resin material substantially insulates the
plurality of coils from the fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The above and other objects, features and advantages of the
present invention will become more apparent from the following
detailed description made with reference to the accompanying
drawings. In the drawings:
[0011] FIG. 1 is a longitudinal partially sectional view showing a
fuel pump according to a first embodiment;
[0012] FIG. 2 is a sectional view taken along the line II-II in
FIG. 1;
[0013] FIG. 3 is a perspective view showing a slant restricting
member of the fuel pump;
[0014] FIG. 4 is a sectional view showing a fuel pump according to
a second embodiment; and
[0015] FIG. 5 is a sectional view showing a fuel pump according to
a third embodiment.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
First Embodiment
[0016] As shown in FIG. 1, a fuel pump 10 of this embodiment is an
in-tank turbine pump that is provided in a fuel tank of a
motorcycle with an engine size of 150 cc, for example.
[0017] The fuel pump 10 includes a pump portion 12 and a motor
portion 13. The motor portion 13 rotates the pump portion 12. The
housing 14 accommodates both the pump portion 12 and the motor
portion 13. A pump case 20 and an end cover 48 are fixed by
crimping both axial ends of the housing 14. The thickness of a
portion of the housing 14 covering the outer circumferential
periphery of the stator core 30 in the motor portion 13 is less
than the thickness of a portion defining a step 15 in the pump
portion 12. The housing 14 is not necessary for defining a magnetic
circuit. Therefore, the outer diameter of the motor portion 13 can
be reduced by reducing the thickness of the housing 14 surrounding
the outer circumferential periphery of the stator core 30.
[0018] The pump portion 12 is a turbine pump that includes pump
cases 20, 22, and an impeller 24. The pump case 22 is abutted
axially onto the step 15 of the housing 14. Thus, the pump case 22
is axially aligned. The pump case 20 is fixed by crimping one end
of the housing 14. Axial force is caused by the crimping, thereby
producing pressure for axially pressing the pump case 22 and the
pump case 20 respectively onto the step 15 and the pump case 22, so
that fuel is sealed.
[0019] The pump cases 20, 22 rotatably accommodate the impeller 24
as a rotor member. The pump cases 20, 22 and the impeller 24 define
pump passages 202 in C-shapes thereamong. Fuel is drawn through an
inlet port 200 provided to the pump case 20, and is pressurized
through the pump passages 202 by rotation of the impeller 24,
thereby being press-fed toward the motor portion 13. The fuel
press-fed toward the motor portion 13 is supplied toward an engine
through an outlet port 206 after passing through a fuel passage 204
defined between the stator core 30 and a rotator 60.
[0020] As referred to FIGS. 1, 2, the motor portion 13 is a
brushless motor that includes the stator core 30, bobbins 40, coils
42, and the rotator 60. The stator core 30 is constructed of six
cores 32 that are circumferentially arranged. An unillustrated
control apparatus controls current supplied to the coils 42 in
accordance with a rotational position of the rotator 60, thereby
switching magnetic poles defined in the inner circumferential
peripheries of the cores 32. The inner circumferential peripheries
of the cores 32 are opposed to the rotator 60.
[0021] As referred to FIG. 2, each of the cores 32 has a tooth 33
and an outer circumferential periphery 34. Each core 32 is
integrally formed by crimping magnetic steel plates, which are
stacked with respect to the axial direction of the core 32. The
tooth 33 protrudes from the center of the outer circumferential
periphery 34 inwardly toward the rotator 60. Each of the bobbins 40
formed of electrically insulative resin engages with each of the
cores 32. Six of the outer circumferential peripheries 34 define a
toroidal core. Each of the outer circumferential peripheries 34 is
in a substantially arc shape that has a circumferentially regular
width.
[0022] Each of the coils 42 is constructed by concentrically
winding a wire around the outer periphery of the bobbin 40 of each
of the cores 32 in a condition where each of the six cores 32 is a
single component before being circumferentially arranged to be the
stator core 30. Each of the coils 42 electrically connects with
each of terminals 44 on the side of the end cover 48 in a condition
depicted by FIG. 1.
[0023] An electrically insulative resin material 46 is charged
between the teeth 33, which are circumferentially adjacent to each
other, thereby being molded such that the electrically insulative
resin material 46 covers the coils 42. The electrically insulative
resin material 46 is integrally molded with the end cover 48 that
covers the end of the stator core 30 on the opposite side of the
pump portion 12 with respect to the stator core 30. The
electrically insulative resin material 46 is integrally formed with
the end cover 48, so that components constructing the fuel pump 10
can be reduced, and manufacturing work for assembling the fuel pump
10 can be reduced.
[0024] As shown in FIG. 3, the slant restricting member 50 has a
through hole in the center thereof. The slant restricting member 50
has claws 52 and fitting holes 54. The claws 52 hook to the bobbins
40. Each of the terminals 44 fits to each of the fitting holes 54.
FIG. 3 depicts a substantially annular slant restricting member 50
before the electrically insulative resin material 46 is molded.
Each of the terminals 44 fits to each of the fitting holes 54 of
the slant restricting member 50, so that the terminals 44 can be
restricted from being inclined and causing interference with
peripheral components when the electrically insulative resin
material 46 is molded of resin.
[0025] As referred to FIGS. 1, 2, the rotator 60 includes a shaft
62 and a permanent magnet 64. The rotator 60 is rotatable around
the inner circumferential periphery of the stator core 30. The
permanent magnet 64 is directly fitted to the outer circumferential
periphery of the shaft 62. The outer circumferential periphery of
the shaft 62 may be knurled. The shaft 62 is rotatably supported by
bearings 26 at both ends. The permanent magnet 64 may be a resin
magnet that is produced by mixing magnetic powder with
thermoplastic resin such as polyphenylene sulfide (PPS). The
permanent magnet 64 is shaped to be substantially cylindrical. The
permanent magnet 64 has eight magnetic poles 65 arranged with
respect to the rotative direction of the rotator 60. The eight
magnetic poles 65 are magnetized toward the outer circumferential
periphery of the permanent magnet 64. The outer circumferential
periphery of the permanent magnet 64 is opposed to the stator core
30. The magnetic poles are different from each other with respect
to the rotative direction of the rotator 60.
[0026] The end cover 48 has the outlet port 206 that accommodates a
valve member 70, a stopper 72, and a spring 74 that construct a
check valve. Thus, the end cover 48 also serves as a housing of the
check valve, so that components constructing the fuel pump 10 can
be reduced, and manufacturing work for assembling the fuel pump 10
can be also reduced.
[0027] The valve member 70 is lifted against bias force of the
spring 74 when pressure of fuel pressurized in the pump portion 12
becomes equal to or greater than predetermined pressure, so that
fuel is discharged toward the engine through the outlet port 206.
The valve member 70 restricts fuel, which is discharged from the
fuel pump 10, from causing reverse flow.
[0028] In the first embodiment, each of the coils 42 is constructed
of the concentrated winding formed around the tooth 33 of each of
the cores 32, so that an occupancy rate of the winding is enhanced
compared with a structure of distributed winding, for example. This
occupancy rate of the winding is a rate of a winding area of the
winding with respect to a winding space, in which the winding is
located. Therefore, a winding space occupied by each of the coils
42 is reduced by increasing the occupancy rate when the number of
the winding is constant. Consequently, the motor portion 13 can be
reduced, so that the fuel pump 10 can be reduced.
[0029] Furthermore, the electrically insulative resin material 46
is charged between the teeth 33, which are circumferentially
adjacent to each other, thereby being molded such that the
electrically insulative resin material 46 covers the coils 42.
Therefore, the coils 42 are protected from corrosion due to
exposure to fuel, and the coils 42 can be restricted from being
exposed to foreign matters by applying a simple structure.
Furthermore, the electrically insulative resin material 46 is
capable of protecting the coils 42, which is constructed of the
concentrated winding, from causing deformation in the winding.
[0030] Furthermore, the teeth 33 of the stator core 30 are separate
from each other. Therefore, the wire can be concentrically wound
around each of the teeth 33 in a condition where each of the teeth
33 is a single component before being circumferentially arranged to
be the stator core 30. Thus, the manufacturing work for
concentrically winding the wire around each of the teeth 33 can be
facilitated.
Second and Third Embodiments
[0031] As shown in FIG. 4, in the second embodiment, a fuel pump 80
includes a stator core 82 that is constructed of a toroidal core 84
and six teeth 85. The six teeth 85 are circumferentially arranged
around the inner circumferential periphery of the toroidal core 84.
The toroidal core 84 and the teeth 85 are separate components. The
teeth 85 are also separate components. The electrically insulative
resin material 46 is charged between the teeth 85, which are
circumferentially adjacent to each other, thereby being molded such
that the electrically insulative resin material 46 covers the coils
42.
[0032] As shown in FIG. 5, in the third embodiment, a fuel pump 90
includes a stator core 92 that is constructed of a toroidal core 94
and six teeth 95. The six teeth 95 are circumferentially arranged.
The six teeth 95 engage with the inner circumferential periphery of
the toroidal core 94. The toroidal core 94 and the teeth 95 are
separate components. The teeth 95 are also separate components. The
electrically insulative resin material 46 is charged between the
teeth 95, which are circumferentially adjacent to each other,
thereby being molded such that the electrically insulative resin
material 46 covers the coils 42.
[0033] In the second and third embodiments, the concentrated
winding can be readily formed by concentrically winding the wire
around the tooth 85, 95 to construct each of the coils 42 in a
condition where each of the teeth 85, 95 is a single component
before being assembled to be the stator core 82, 92.
[0034] Furthermore, in the third embodiment, each of the coils 42
is wound around each of the teeth 95, and the teeth 95 engage with
the toroidal core 94. Therefore, the teeth 95 can be readily
aligned with respect to the circumferential direction.
[0035] In the above embodiments, the brushless motor may be at
least partially submerged in fluid such as fuel. The electrically
insulative resin material 46 is molded such that the electrically
insulative resin material 46 at least partially covers the
plurality of coils 42, so that the electrically insulative resin
material 46 substantially insulates the coils 42 from the fluid.
Thus, the coils 42 can be protected from being exposed to the
fluid.
Other Embodiment
[0036] In the above embodiments, the teeth, which are
circumferentially arranged to construct the stator core, are
separate components. Alternatively, the teeth may be integrally
formed such that the teeth are circumferentially arranged.
[0037] In the above embodiments, the pump portion 12 is constructed
of the turbine pump including the impeller 24. Alternatively, the
pump portion may be constructed of a pump having another structure
such as a gear pump.
[0038] The above structures of the embodiments can be combined as
appropriate.
[0039] In the above embodiments, the structures of the brushless
motor is applied to the fuel pump. However, the above structures
are not limited to the application of the fuel pumps. The above
structures can be applied to any other fluid pumps.
[0040] Various modifications and alternations may be diversely made
to the above embodiments without departing from the spirit of the
present invention.
* * * * *