FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
MOTOR AND AIR CONDITIONER USING THE SAME;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

2
Description
Technical Field
[0001]
5 The present invention relates to a motor including a
consequent pole rotor, and an air conditioner including the
same.
Background Art
[0002]
10 In recent years, motors using high-performance rare
earth magnets have been employed in many electrical devices.
Rare earth magnets contain rare elements and thus are costly,
and have high risk in terms of securing resources. Thus, it
is required to reduce magnet usage as much as possible.
15 [0003]
As a way to reduce magnet usage, it is conceivable to
form a motor by using a consequent pole rotor. In a
consequent pole rotor, magnet magnetic poles by magnets and
salient poles formed in a rotor core not by magnets are
20 circumferentially alternately arranged, and thus it is
possible to form a rotor while reducing the number of
magnets to half the usual number.
[0004]
On the other hand, in a consequent pole rotor, since
25 problems may be caused by a shaft being magnetized by
leakage magnetic flux, a non-magnetic material may be used
as the material of the shaft. Non-magnetic materials
generally have lower thermal conductivity than magnetic
materials, and there is a problem in that heat generated in
30 the motor is difficult to dissipate to the outside through
the shaft.
[0005]
As a way to improve heat dissipation characteristics
from a motor, there is known a cooling device that generates

3
cooling air flowing along a side surface of a casing with a
cooling fan mounted to a shaft projecting outside the casing
(see, e.g., Patent Literature 1).
Citation List
5 Patent Literature
[0006]
Patent Literature 1: Japanese Patent Application
Publication No. H6-346885
Summary of Invention
10 Technical Problem
[0007]
However, it is difficult to sufficiently cool a rotor
located near a center of a motor only by flowing air to an
outer surface of a casing as in the prior art document. In
15 particular, when the casing is molded from a resin that is
an insulating material, even the heat dissipation from the
casing is insufficient, and a rise in temperature in the
motor may reduce the efficiency or output of the motor.
[0008]
20 The present invention has been made to solve the
problems as described above, and provides a motor having a
sufficient heat dissipation function even when a nonmagnetic material having low thermal conductivity is used
for a shaft of a consequent pole rotor.
25 Solution to Problem
[0009]
To achieve the above object, a motor according to the
present invention includes: a stator; a consequent pole
rotor including a rotor core and a magnet; a casing housing
30 the stator and the rotor; a shaft including a non-magnetic
material and fixed to the rotor; and a first heat
dissipation promoting means that rotates with the shaft.
Advantageous Effects of Invention
[0010]

4
The motor according to the present invention
continuously generates airflow along a shaft 8 with a first
heat dissipation promoting means provided to an impeller 21
connected to the shaft 8, and thus promotes heat dissipation
5 through a heat dissipation path from an inside of the motor
through the shaft 8 even when a consequent pole rotor is
employed and the shaft made of a non-magnetic material is
used. Thereby, it is possible to prevent problems due to
overheat in the motor 1.
10 Brief Description of Drawings
[0011]
FIG. 1 is an axial sectional view of a motor using a
consequent pole rotor according to a first embodiment of the
present invention.
15 FIG. 2 is a radial sectional view of the consequent
pole rotor and a stator according to the first embodiment of
the present invention.
FIG. 3 is a configuration diagram illustrating an
example in which the motor of the first embodiment of the
20 present invention is used as a blower.
FIG. 4 is a sectional view and a plan view illustrating
a structure of a bracket of the motor of the first
embodiment of the present invention.
FIG. 5 is a configuration diagram illustrating a
25 modification in which the motor of the first embodiment of
the present invention is used as a blower.
FIG. 6 is a plan view and a perspective view
illustrating a shape and an installation state of a heat
dissipation fin of the motor of the first embodiment of the
30 present invention.
FIG. 7 is a configuration diagram illustrating an
example in which a motor of a second embodiment of the
present invention is used as a blower.
FIG. 8 is a perspective view illustrating a shape of a

5
connection 23 between the motor and an impeller in the
second embodiment of the present invention.
FIG. 9 is a perspective view illustrating shapes of a
heat dissipation fin and blower blades of a motor of a third
5 embodiment of the present invention.
FIG. 10 is a view illustrating an example of a
configuration of an air conditioner using the motor of any
one of the first to third embodiments of the present
invention.
10 Description of Embodiments
[0012]
Motors using consequent pole rotors and air
conditioners according to embodiments of the present
invention will be described below in detail with reference
15 to the drawings. The present invention is not limited by the
embodiments.
[0013]
First Embodiment
FIG. 1 is an axial sectional view of a motor including
20 a consequent pole rotor according to a first embodiment of
the present invention. The motor 1 illustrated in FIG. 1
includes an annular stator 5 including a stator core 2 and
coils 3, and a rotor 9 including a rotor core 6, magnets 7,
and a shaft 8. Also, a casing 10 is formed by molding a
25 resin material around an outer periphery of the stator 5,
and the rotor 9 is supported inside the stator 5 by a
bracket 11 attached to an axial end face of the casing 10.
Also, a disk-shaped heat dissipation fin 12 is connected to
the shaft 8, which projects outside the casing 10.
30 [0014]
FIG. 2 is a radial sectional view of the rotor 9 and
stator 5 of the motor 1. The stator 5 has a shape with
multiple cores projecting from an outer periphery side of
the stator core 2 toward a center of the stator core 2, and

6
is formed by stacking multiple electromagnetic steel sheets
that are magnetic and have thicknesses of 0.2 mm to 0.5 mm.
Conductive wire composed primarily of copper or aluminum is
wound around the multiple projecting cores to form the coils
5 3. An insulator 4 ensures insulation between the stator core
2 and the coils 3.
[0015]
The insulator 4 is formed integrally with the stator
core 2, or is produced separately from the stator core 2 and
10 then fitted to the stator core 2. The insulator 4 is formed
by an insulating resin, such as polybutylene telephthalate
(PBT), polyphenylene sulfide (PPS), liquid crystal polymer
(LCP), or polyethylene terephthalate (PET), or an insulating
film having a thickness of 0.035 mm to 0.4 mm.
15 [0016]
The rotor 9 is a consequent pole rotor of an embedded
magnet type, and is located with a slight gap between the
rotor 9 and an inner periphery of the stator 5. The rotor
core 6, which is circular, is formed by stacking multiple
20 electromagnetic steel sheets having thicknesses of 0.2 mm to
0.5 mm. In a peripheral portion thereof, the magnets 7, the
number of which is, for example, 5, are inserted at regular
intervals. As the magnets 7, rare earth magnets composed
primarily of neodymium (Nd) or samarium (Sm) or ferrite
25 magnets composed primarily of iron (Fe) are used. Also, the
shaft 8, which is made of SUS 304, which is a non-magnetic
material, is fixed to a center of the rotor core 6 by press
fitting, caulking, shrink fitting of the rotor core, resin
integral molding between the rotation shaft and the rotor
30 core, or other methods. The material of the shaft is not
limited to this, and may be other austenitic stainless
steels or materials other than ferrous materials.
[0017]
FIG. 3 is a configuration diagram illustrating an

7
example of a state in which the motor 1 of the embodiment of
the present invention is actually used. In the first
embodiment of the present invention, an impeller 21, which
is a rotating body, is connected to the shaft 8, which
5 projects from the motor 1, thereby forming an axial flow
blower. Multiple vanes 22, a connection 23, and blower
blades 24 are integrally formed of a resin material, such as
polypropylene, to form the impeller 21.
[0018]
10 The blower blades 24, which are a first heat
dissipation promoting means, are formed by multiple plates
projecting from an end face of the connection 23, which is
formed in a cylindrical shape, on a side facing the motor 1
toward the motor 1. In the example illustrated in FIG. 3,
15 the blower blades 24 are formed by four flat plates provided
radially from a shaft center. However, the blade shapes and
the number of blades are not limited to this. The blower
blades 24 may be inclined forward or backward with respect
to the rotation direction, instead of being provided
20 parallel to radial directions, and the number of blades may
be increased. Also, it is possible to improve the blowing
efficiency by forming the blades to have cross sections
having streamlined shapes instead of flat plate shapes.
[0019]
25 Next, effects of the first embodiment will be described.
The blower blades 24 functions as a centrifugal blower
with rotation of the impeller 21, and generates airflow
outward from the vicinity of the shaft 8. Accordingly,
airflow is generated in the directions of the arrows
30 illustrated in FIG. 3 in a space between the motor 1 and the
impeller 21, and thus airflow along a surface of the shaft 8,
which is hot due to heat generation in the motor,
continuously occurs, promoting heat dissipation from the
shaft 8 to the external space.

8
[0020]
In general, a rotating body like the impeller 21
generates airflow in only centrifugal directions or an axial
flow direction without generating airflow toward the shaft 8,
5 and thus moves little air near the shaft 8. Although the
blower blades 24 also blow air in directions away from the
shaft 8, they cause air between the impeller 21 and the
bracket 11 to flow outward, thereby indirectly generating
airflow toward the shaft 8.
10 [0021]
Thus, even when the shaft 8 is made of a non-magnetic
material having low thermal conductivity, it is possible to
prevent overheat in the casing 10 by virtue of sufficient
heat dissipation by the blower blades 24. Also, since the
15 impeller 21 and blower blades 24 are integrally formed,
neither additional parts nor assembly processing are needed,
and it is possible to obtain a great heat dissipation
promoting effect without increasing the material cost or
processing cost.
20 [0022]
FIG. 4 is a sectional view and a plan view of the
bracket 11 of the first embodiment of the present invention
as illustrated in FIG. 1. It is a member made of a metallic
material, such as a steel sheet, and having, in its center,
25 a hole through which the shaft 8 passes, and is fixed to an
opening side of the casing 10 by being press fitted thereto.
The way of connecting the casing 10 and the bracket 11 is
not limited to this, and may be screw fastening, adhesion,
or other ways.
30 [0023]
At least one through hole 31 is formed in the bracket
11 such that an internal space of the casing 10 in which the
rotor core 6 is housed and the external space communicate
with each other through the through hole 31. Thus, it is

9
possible to improve the heat dissipation performance by
feeding part of the airflow generated by the blower blades
24 directly to the rotor core 6 housed in the casing 10.
Also, since the bracket 11 is made of a metallic material
5 having a higher thermal conductivity than the mold resin, it
becomes hot due to heat generation by the stator 5 and rotor
9, improving the heat dissipation performance from the
surface of the bracket 11 to the external space.
[0024]
10 Also, a groove portion 13 formed in the shaft 8
increases the surface area of the shaft 8 and converts the
airflow generated by the blower blades 24 into turbulent
flow, thereby serving as a second heat dissipation promoting
means to increase a convective heat transfer effect.
15 [0025]
While the second heat dissipation promoting means has
been described as being the groove portion 13, a
modification of the second heat dissipation promoting means
will be described below with reference to FIGs. 5 and 6. FIG.
20 5 is a configuration diagram of the blower with the heat
dissipation fin 12 connected to the groove portion 13. The
heat dissipation fin 12 is disposed between the impeller 21
and the motor 1.
[0026]
25 FIG. 6 is a plan view of the heat dissipation fin 12 as
illustrated in FIG. 5, and a perspective view illustrating a
state in which the heat dissipation fin 12 is connected to
the shaft 8. The disk-shaped heat dissipation fin 12, which
is the second heat dissipation promoting means, is made of,
30 for example, S45C, which is a steel material having a higher
thermal conductivity than the shaft 8, and is fitted in the
groove portion 13 provided in the shaft 8. A diameter of a
hole at a central portion of the heat dissipation fin 12 is
slightly smaller than a diameter of the groove portion 13,

10
and the heat dissipation fin 12 is fitted tightly due to
elastic deformation of the heat dissipation fin 12. Thereby,
the heat dissipation fin 12 is in close contact with the
shaft 8 at the contact surface with the shaft 8 so as not to
5 prevent heat transfer, and heat in the motor 1 efficiently
transfers to the heat dissipation fin 12 through the shaft 8.
The heat dissipation fin 12 may be made of copper or
aluminum having a higher thermal conductivity than steel
materials.
10 [0027]
As above, in the first embodiment, when a blower is
formed by connecting the impeller 21 to the motor 1, since
the blower blades 24 are provided to the connection 23, it
is possible to generate airflow along the shaft 8. Thereby,
15 heat dissipation from the shaft 8 is promoted, and even when
a non-magnetic material having low thermal conductivity is
used for the shaft 8, it is possible to avoid problems due
to overheat by sufficiently cooling the inside of the motor
1.
20 [0028]
Also, since the blower blades 24 are formed integrally
with the impeller 21 and connection 23, no additional parts
for cooling the shaft 8 are needed, and it is possible to
reduce the material cost and processing cost.
25 [0029]
Also, since the groove portion 13 is formed in the
shaft 8, it is possible to improve the heat dissipation
performance from the shaft 8 by increasing the heat
dissipation area and converting the airflow generated by the
30 blower blades 24 into turbulent flow. In another aspect, the
heat dissipation fin 12 having a higher thermal conductivity
than the shaft 8 may be fitted in the groove portion 13.
With such a configuration, the surface area for heat
dissipation from the shaft 8 is further increased, and it is

11
possible to improve the heat dissipation performance.
[0030]
Also, since the bracket 11 includes the through hole 31
such that the internal space and external space of the
5 casing 10 communicate with each other through the through
hole 31, it is possible to improve the heat dissipation
performance in the motor 1 by feeding airflow generated by
the blower blades 24 directly to the rotor core 6. Also,
since the bracket 11 is made of a metallic material having a
10 higher thermal conductivity than the mold resin, the heat
dissipation performance from the surface of the bracket 11
is also improved.
[0031]
Although the first embodiment describes a case where
15 the blower is formed by connecting the impeller 21 to the
motor 1, this is not mandatory, and it may be applied to
mechanical equipment, such as hermetic refrigerant
compressors or machine tools.
[0032]
20 Second Embodiment
While the first embodiment describes a case where the
connection 23 is formed to be solid, a second embodiment
describes a case of using a relatively large impeller in
which the connection 23 is formed in a hollow cylindrical
25 shape for the purpose of making the wall thickness
substantially uniform.
[0033]
FIG. 7 is a sectional view illustrating an actual use
example when the connection 23 of the first embodiment of
30 the present invention has a hollow cylindrical shape. The
connection 23 has a hollow cylindrical shape with an opening
on the motor 1 side, and multiple vanes 22 are provided to
an outer periphery side cylindrical portion of the
connection 23, thereby forming an impeller 21. Also,

12
multiple reinforcement ribs 26, which are radially arranged,
are formed between a center side cylindrical portion 25, in
which the shaft 8 is fitted, and the outer periphery side
cylindrical portion.
5 [0034]
FIG. 8 illustrates a perspective view of the connection
23 of the impeller 21 connected to the motor 1 according to
this embodiment. The reinforcement ribs 26 project from the
connection 23 toward the motor 1 to form blower blades 24,
10 and has a function of blowing air near the shaft 8 outward
by centrifugal force, thereby generating airflow along the
shaft 8.
[0035]
As above, in the second embodiment, since the
15 reinforcement ribs 26 of the connection 23 formed in a
hollow cylindrical shape project toward the motor 1 to form
the blower blades 24, it is possible to promote heat
dissipation from the shaft 8 by generating airflow near the
shaft 8 and prevent overheat in the motor 1.
20 [0036]
Also, since the blower blades 24 are formed by making
the reinforcement ribs 26 simply project axially, it is
possible to simply provide the blower blades 24 almost
without changing the shape of the impeller 21.
25 [0037]
Third Embodiment
While the first and second embodiments describe cases
where the first heat dissipation promoting means is provided
to the connection 23, a third embodiment describes an
30 example where the blower blades 24 are provided as the first
heat dissipation promoting means to the heat dissipation fin
12.
[0038]
FIG. 9 is a view illustrating a modification of the

13
position where the blower blades 24 of the first embodiment
of the present invention are formed. The blower blades 24
are formed on the heat dissipation fin 12 fitted in the
groove portion 13 formed in the shaft 8 such that the blower
5 blades 24 are cut and raised from a surface of the heat
dissipation fin 12. As the shaft 8 rotates, the heat
dissipation fin 12 also rotates, the blower blades 24
generate airflow flowing outward from the vicinity of the
groove portion 13 in which the heat dissipation fin 12 is
10 fitted. This airflow indirectly forms airflow flowing toward
the groove portion 13 along the surfaces of the shaft 8 and
heat dissipation fin 12, and thus it is possible to promote
heat dissipation from the shaft 8 more effectively.
[0039]
15 As above, in the third embodiment, since the blower
blades 24 are formed integrally with the heat dissipation
fin 12, airflow is generated toward a portion where the heat
dissipation fin 12 and shaft 8 are fitted to each other, and
it is possible to promote heat dissipation from the shaft 8
20 more effectively.
[0040]
Also, it is possible to combine the first heat
dissipation member described in the third embodiment and the
first heat dissipation member described in the first or
25 second embodiment.
[0041]
Fourth Embodiment
FIG. 10 is a view illustrating an example of a
configuration of an air conditioner according to any one of
30 the first to third embodiments of the present invention. The
air conditioner 40 includes an indoor unit 41 and an outdoor
unit 42 connected to the indoor unit 41. An indoor fan (not
illustrated) is installed in the indoor unit 41, and an
outdoor fan 43 is installed in the outdoor unit 42. Also, a

14
compressor (not illustrated) is installed in the outdoor
unit 42. The motor 1 of any one of the first to third
embodiments is used in each of the indoor fan, outdoor fan
43, and compressor.
5 [0042]
By using the motor 1 according to the first embodiment
as a driving source of each of the indoor fan, outdoor fan
43, and compressor, heat dissipation from the insides of the
motors 1 is promoted, preventing reduction in the operating
10 efficiency of the air conditioner 40.
[0043]
The motor 1 of any one of the first to third
embodiments can be installed in electrical equipment other
than the air conditioner 40, and also in this case, it is
15 possible to provide the same advantages as the embodiment.
[0044]
Also, the configurations described in the above
embodiments show examples of the content of the present
invention, and may be combined with other known techniques,
20 and part of the configurations may be omitted or modified
without departing from the gist of the present invention.
Reference Signs List
[0045]
1 motor, 2 stator core, 3 coil, 4 insulator, 5 stator,
25 6 rotor core, 7 magnet, 8 shaft, 9 rotor, 10 casing, 11
bracket, 12 heat dissipation fin, 13 groove portion, 21
impeller, 22 vane, 23 connection, 24 blower blade, 25 center
side cylindrical portion, 26 reinforcement rib, 31 through
hole, 40 air conditioner, 41 indoor unit, 42 outdoor unit,
30 43 outdoor fan.

We Claim:
1. A motor comprising:
a stator;
5 a consequent pole rotor including a rotor core and a
magnet;
a casing housing the stator and the rotor;
a shaft comprising a non-magnetic material and fixed to
the rotor; and
10 a first heat dissipation promoting means that rotates
with the shaft.
2. The motor of claim 1, wherein the first heat
dissipation promoting means is one or more blower blades.
15
3. The motor of claim 2, wherein the blower blades are
formed integrally with a connection that fixes a rotating
body to the shaft.
20 4. The motor of claim 3, further comprising between the
rotor and the connection a second heat dissipation promoting
means that increases a surface area of the shaft.
5. The motor of any one of claims 1 to 4, further
25 comprising a bracket supporting the shaft, the bracket
comprising a metallic material and connected to an end face
of the casing.
6. The motor of claim 5, wherein the bracket includes a
30 through hole for allowing a space housing the rotor and an
outside of the casing to communicate with each other.
7. The motor of claim 3, wherein the blower blades project
from an end face of the connection that faces the rotor.

16
8. The motor of claim 3, wherein the connection is formed
in a hollow cylindrical shape, and the blower blades are
formed integrally with reinforcement ribs radially disposed
5 in an inside of the connection.
9. The motor of claim 4, wherein the second heat
dissipation promoting means is a groove portion formed
between the rotor and the connection.
10
10. The motor of claim 9, wherein the second heat
dissipation promoting means is a heat dissipation fin fitted
in the groove portion.
15 11. The motor of claim 10, wherein the heat dissipation fin
comprises a material having a higher thermal conductivity
than a material of the shaft.
12. The motor of claim 10 or 11, wherein the heat
20 dissipation fin is formed integrally with the blower blades.
13. The motor of claim 1, wherein the casing is formed by a
resin material molded around the stator.
14. An air conditioner comprising the motor of any one of
claims 1 to 13.