FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
STATOR, ELECTRIC MOTOR, COMPRESSOR, AND AIR CONDITIONER;
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.

DESCRIPTION
TECHNICAL FIELD
[0001]
The present invention relates to a stator of an electric
motor.

BACKGROUND ART 5 [0002]
In the field of electric motors, increase in power and
size reduction have been required in recent years. The
increase in power of an electric motor causes an increase in
current flowing in a coil of a stator. The size reduction of 10 the electric motor also causes an increase in current necessary
for obtaining the same power. The increase in current flowing
in the coil causes a temperature rise of the coil. The
temperature rise of the coil causes a decrease in efficiency of
the electric motor. Thus, it is preferable to reduce a 15 temperature rise of the coil by dissipating heat of the coil to
the outside.
In an electric motor for use in a compressor, for example,
a stator can be formed such that a coil-end part of a coil
contacts refrigerant and lubricating oil in a compressor. Thus, 20 heat generated in the coil is preferably dissipated from the
coil-end part exposed to the outside of the coil. The
calorific volume of the coil depends on the level of electrical
resistance, and thus, electrical resistance of the coil is
preferably low in order to reduce heat generation of the coil. 25 In recent years, in order to reduce costs and weight of
an electric motor, it has been proposed to use an aluminium
wire coil as well as a copper wire coil as a winding of the
coil (see, for example, Patent Reference 1).
PRIOR ART REFERENCE 30 PATENT REFERENCE
[0003]
Patent Reference 1: WO2014/188466
SUMMARY OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
[0004]
In the case of using a coil formed of different types of
windings, however, heat dissipation efficiency from a coil-end 5 part of the coil is insufficient in a conventional technique,
and thus, there has been a problem of an insufficient reduction
of a temperature rise of a stator, especially a temperature
rise of the coil.
[0005] 10 It is therefore an object of the present invention to
enhance heat dissipation efficiency in a coil-end part of a
coil.

MEANS OF SOLVING THE PROBLEM
[0006] 15 A stator of the present invention includes: a stator
core; and a coil wound around the stator core and including at
least one first winding and at least one second winding
connected to the at least one first winding in parallel, the at
least one second winding being formed of a material different 20 from the at least one first winding, wherein the coil includes
a coil-end part located outside the stator core, and the stator
satisfies: (C1/S1) > (C2/S2) where P1 is a straight line that
halves a maximum height of the coil-end part from a point of
contact of the coil with the stator core in the coil-end part, 25 S1 is a total cross-sectional area on a first side of the coilend
part that is an opposite side of the straight line P1 from
the stator core, S2 is a total cross-sectional area on a second
side of the coil-end part that is an opposite side of the
straight line P1 from the first side, C1 is a total cross- 30 sectional area of the at least one first winding on the first
side of the coil-end part, and C2 is a total cross-sectional
area of the at least one first winding on the second side of
the coil-end part.

EFFECTS OF THE INVENTION
[0007]
According to the present invention, heat dissipation
efficiency in the coil-end part of the coil can be enhanced.
BRIEF DESCRIPTION OF THE DRAWINGS 5 [0008]
FIG. 1 is a plan view schematically illustrating a
structure of an electric motor according to a first embodiment
of the present invention.
FIG. 2 is a view illustrating a connection state of a 10 coil between a first winding and a second winding.
FIG. 3 is a cross-sectional view of a bundle of a coil
taken along a line C3-C3 illustrated in FIG. 1.
FIG. 4 is a cross-sectional view of the bundle of the
coil taken along the line C3-C3 illustrated in FIG. 1. 15 FIG. 5 is a cross-sectional view of the bundle of the
coil taken along line the C3-C3 illustrated in FIG. 1.
FIG. 6 is a cross-sectional view illustrating a scroll
compressor.
FIG. 7 is a diagram illustrating an air conditioner (also 20 referred to as a refrigeration cycle apparatus).

MODE FOR CARRYING OUT THE INVENTION
[0009]
FIRST EMBODIMENT
In an xyz orthogonal coordinate system shown in each 25 drawing, a z-axis direction (z axis) represents a direction
parallel to an axis Ax of a rotor 3 of an electric motor 1, an
x-axis direction (x axis) represents a direction orthogonal to
the z-axis direction (z axis), and a y-axis direction (y axis)
represents a direction orthogonal to both of the z-axis 30 direction and the x-axis direction. The axis Ax is a rotation
center of the rotor 3. The direction parallel to the axis Ax
will be referred to as an “axial direction of the rotor 3” or
simply as an “axial direction.” A radial direction is a
direction orthogonal to the axis Ax.
[0010]
FIG. 1 is a plan view schematically illustrating a
structure of the electric motor 1 according to a first
embodiment of the present invention. An arrow D1 represents a 5 circumferential direction of a stator 2 about the axis Ax. The
arrow D1 also represents a circumferential direction of the
rotor 3 about the axis Ax. The circumferential directions of
the stator 2 and the rotor 3 will be also referred to simply as
“circumferential directions.” 10 The electric motor 1 includes the stator 2 and the rotor
3. The electric motor 1 is, for example, an induction motor.
The electric motor 1 is used for, for example, a compressor
such as a scroll compressor.
[0011] 15 The rotor 3 is rotatably disposed inside the stator 2.
[0012]
The stator 2 includes a stator core 21 and a coil 22
(also referred to as a stator coil).
The stator core 21 is formed in a ring shape. The stator 20 core 21 is formed by stacking a plurality of electromagnetic
steel sheets in the axial direction. The plurality of
electromagnetic steel sheets are fixed together by swaging.
Each of the plurality of electromagnetic steel sheets is
punched into a predetermined shape. Each of the plurality of 25 electromagnetic steel sheets has a thickness of, for example,
0.1 mm to 0.7 mm.
[0013]
The stator core 21 includes a yoke 21a and a plurality of
teeth 21b. The yoke 21a is formed in an annular ring shape. 30 Each of the teeth 21b extends radially from the yoke 21a. In
other words, each of the teeth 21b projects from the yoke 21a
toward the rotation center of the rotor 3.
[0014]
The teeth 21b are arranged at regular intervals in the
circumferential direction. Space formed between each adjacent
two of the teeth 21b in the circumferential direction is a slot.
The number of the teeth 21b is, for example, 30. It should be
noted that the number of the teeth 21b is not limited to 30. 5 Front ends of the teeth 21b expand in the circumferential
direction.
[0015]
The coil 22 is wound around the stator core 21.
Specifically, the coil 22 is wound around the teeth 21b. In 10 the example illustrated in FIG. 1, the coil 22 is wound around
the stator core 21 by distributed winding. The winding of the
coil 22 is not limited to the distributed winding. For example,
the coil 22 may be wound around the stator core 21 by
concentrated winding. 15 [0016]
The coil 22 includes a plurality of bundles 220. Each of
the bundles 220 will be also referred to as a coil bundle. In
the example illustrated in FIG. 1, each of the bundles 220 is
wound around the stator core 21 by distributed winding. The 20 coil 22 includes coil-end parts 22a located outside the stator
core 21. Specifically, each of the bundles 220 includes the
coil-end part 22a. The coil-end parts 22a are located outside
the stator core 21 in the axial direction. In other words, the
coil-end parts 22a are parts of the coil 22 located outside the 25 stator core 21 in the axial direction. That is, the coil-end
parts 22a are parts of the coil 22 illustrated in FIG. 1. It
should be noted that the number of the bundles 220 and the
number of the coil-end parts 22a are not limited to the example
illustrated in FIG. 1. 30 [0017]
FIG. 2 is a view illustrating a connection state of the
coil 22 between a first winding 221 and a second winding 222.
The coil 22 includes at least one first winding 221 and
at least one second winding 222. The second winding 222 is
connected to the first winding 221 in parallel. That is, each
of the bundles 220 is constituted by the at least one first
winding 221 and the at least one second winding 222. In the
example illustrating FIG. 2, the coil 22 is a three-phase coil 5 having a U phase, a V phase, and a W phase, and a connection of
the coil 22 is a Y connection.
[0018]
The first winding 221 is made of a material different
from the second winding 222. The second winding 222 is made of 10 a material different from the first winding 221. That is, the
first winding 221 and the second winding 222 are made of
different materials. The electrical resistivity of the second
winding 222 is higher than that of the first winding 221. That
is, the thermal conductivity of the second winding 222 is lower 15 than that of the first winding 221.
[0019]
In general, as the diameter of a winding decreases, heat
loss density increases. In this embodiment, the diameter of
the first winding 221 is smaller than that of the second 20 winding 222. In this case, a heat loss quantity (also referred
to as a “heat loss” or simply “loss”) generated in the first
winding 221 might be larger than a heat loss quantity generated
in the second winding 222. For example, in a cross section
(e.g., a yz plane illustrated in FIG. 3) of each coil-end part 25 22a of the coil 22, if the total cross-sectional area of the
first winding 221 is equal to the total cross-sectional area of
the second winding 222, the heat loss quantity generated in the
first winding 221 is larger than the heat loss quantity
generated in the second winding 222. 30 [0020]
In this embodiment, the first winding 221 is a copper
wire, and the second winding 222 is an aluminum wire. It
should be noted that the first winding 221 is not limited to
the copper wire, and the second winding 222 is not limited to
the aluminum wire.
[0021]
FIG. 3 is a cross-sectional view of the bundle 220
(specifically, the coil-end part 22a of the bundle 220) of the 5 coil 22 taken along a line C3-C3 illustrated in FIG. 1. An
arrow L1 represents a heat dissipation path from a first side
of the coil-end part 22a. An arrow L2 represents a heat
dissipation path from a second side of the coil-end part 22a.
Heat of the coil-end part 22a is dissipated toward the heat 10 dissipation paths L1 and L2, especially the heat dissipation
path L1.
[0022]
A straight line P1 is a line that halves the maximum
height of the coil-end part 22a from a point of contact of the 15 coil 22 with the stator core 21 in the coil-end part 22a. In
the example illustrated in FIG. 3, the maximum height of the
coil-end part 22a from the point of contact of the coil 22 with
the stator core 21 is expressed by 2 × R1. The maximum height
of the coil-end part 22a is a maximum height in the axial 20 direction.
[0023]
The first side of the coil-end part 22a is an opposite
side of the straight line P1 from the stator core 21.
Specifically, the first side of the coil-end part 22a is a 25 first region 201 at a +z side of the straight line P1. The
second side of the coil-end part 22a is an opposite side of the
straight line P1 from the first side of the coil-end part 22a.
Specifically, the second side of the coil-end part 22a is a
second region 202 at a −z side of the straight line P1. That 30 is, a cross section of the coil-end part 22a includes the first
region 201 and the second region 202 on the yz plane.
[0024]
The first region 201 is a region surrounded by the
straight line P1 and an outer edge formed by tangents to each
winding (i.e., the first winding 221 or the second winding 222)
disposed at the outer end on the first side of the bundle 220
on the yz plane. The second region 202 is a region surrounded
by the straight line P1 and an outer edge formed by tangents to 5 each winding (i.e., the first winding 221 or the second winding
222) disposed at the outer end on the second side of the bundle
220 on the yz plane.
[0025]
In the example illustrated in FIG. 3, at least one first 10 winding 221 and at least one second winding 222 are disposed in
the first region 201, and at least one first winding 221 and at
least one second winding 222 are also arranged in the second
region 202.
[0026] 15 FIG. 4 is a cross-sectional view of the bundle 220
(specifically, the coil-end part 22a of the bundle 220) of the
coil 22 taken along the line C3-C3 illustrated in FIG. 1.
Specifically, FIG. 4 is a cross-sectional view illustrating
another example of the bundle 220 of the coil 22. 20 As illustrated in FIG. 4, only at least one first winding
221 may be disposed in the first region 201. In this case, no
second winding 222 is present in the first region 201.
[0027]
Let S1 be a total cross-sectional area of the coil-end 25 part 22a on the first side. That is, the total cross-sectional
area S1 is an area of the first region 201 on the yz plane.
Let S2 be a total cross-sectional area of the coil-end part 22a
on the second side. The total cross-sectional area S2 is an
area of the second region 202 on the yz plane. Let C1 be a 30 total cross-sectional area of at least one first winding 221 of
the coil-end part 22a on the first side. In other words, the
total cross-sectional area C1 is the sum of cross-sectional
areas of the first windings 221 disposed in the first region
201. Let C2 be a total cross-sectional area of at least one
first winding 221 of the coil-end part 22a on the second side.
In other words, the total cross-sectional area C2 is the sum of
cross-sectional areas of the first windings 221 disposed in the
second region 202. 5 [0028]
In this case, the stator 2 satisfies (C1/S1) > (C2/S2).
Here, C1/S1 is a ratio of at least one first winding 221
(specifically, the total cross-sectional area C1 of the at
least one first winding 221) to the total cross-sectional area 10 S1. In addition, C2/S2 is a ratio of at least one first winding
221 (specifically, the total cross-sectional area C2 of at
least one first winding 221) to the total cross-sectional area
S2. In this manner, heat dissipation efficiency in the stator
2 can be enhanced. 15 [0029]
Let A1 be a total cross-sectional area of at least one
second winding 222 disposed on the first side of the coil-end
part 22a, and let A2 be a total cross-sectional area of at
least one second winding 222 disposed on the second side of the 20 coil-end part 22a. In other words, the total cross-sectional
area A1 is a sum of cross-sectional areas of the second
windings 222 disposed in the first region 201, and the total
cross-sectional area A2 is a sum of cross-sectional areas of
the second windings 222 disposed in the second region 202. In 25 this case, the stator 2 satisfies (C1/S1) > (A1/S1). In this
manner, heat dissipation efficiency in the stator 2 can be
further enhanced.
[0030]
In addition, the stator 2 preferably satisfies (C1/A1) > 30 (C2/A2). In this manner, heat dissipation efficiency in the
stator 2 can be further enhanced.
[0031]
FIG. 5 is a cross-sectional view of the bundle 220
(specifically, the coil-end part 22a of the bundle 220) of the
coil 22 taken along the line C3-C3 illustrated in FIG. 1.
A straight line P2 is a line that halves the straight
line P1 on a cross section of the coil-end part 22a. Thus, the
length of the straight line P1 on the cross section of the 5 coil-end part 22a is expressed by 2 × R2. A radius r is a
radius about an intersection point of the straight line P1 and
the straight line P2 on a cross section of the coil-end part
22a. The radius r is smaller than a half of the length of the
straight line P1 (i.e., R2) and a half of the length of the 10 straight line P2 (i.e., R1) on the cross section of the coilend
part 22a.
[0032]
Let SO1 be a total cross-sectional area of a portion
located outside a region surrounded by the radius r on the 15 first side of the coil-end part 22a. Let Si1 be a total crosssectional
area of the region surrounded by the radius r on the
first side of the coil-end part 22a. The region surrounded by
the radius r is a circle having the radius r about the
intersection point of the straight line P1 and the straight 20 line P2 on the yz plane. The total cross-sectional area SO1 is
an area of the portion located outside the region surrounded by
the radius r in the first region 201 on the yz plane. In other
words, the total cross-sectional area SO1 is an area obtained
by subtracting a semicircle having the radius r from the total 25 cross-sectional area S1. The total cross-sectional area Si1 is
an area of a region surrounded by the radius r in the first
region 201 on the yz plane. In other words, the total crosssectional
area Si1 is an area of a semicircle having the radius
r in the first region 201. 30 [0033]
On the yz plane, let CO1 be a total cross-sectional area
of at least one first winding 221 disposed outside the region
surrounded by the radius r in the first region 201. In other
words, the total cross-sectional area CO1 is a sum of crosssectional
areas of the first windings 221 disposed outside the
region surrounded by the radius r in the first region 201. On
the yz plane, let Ci1 be a total cross-sectional area of at
least one first winding 221 disposed in the region surrounded 5 by the radius r in the first region 201. In other words, the
total cross-sectional area Ci1 is a sum of cross-sectional
areas of the first windings 221 disposed in the region
surrounded by the semicircle having the radius r in the first
region 201. 10 [0034]
In this case, the stator 2 satisfies (CO1/SO1) > (Ci1/Si1).
Here, CO1/SO1 is a ratio of at least one first winding 221
(specifically, the total cross-sectional area CO1 of at least
one first winding 221) to the total cross-sectional area SO1. 15 In addition, Ci1/Si1 is a ratio of at least one first winding
221 (specifically, the total cross-sectional area Ci1 of at
least one first winding 221) to the total cross-sectional area
Si1. In this manner, heat dissipation efficiency in the stator
2 can be further enhanced. 20 [0035]

Next, a relationship between the diameter of the first
winding 221 and the diameter of the second winding 222 will be
described. Since the first winding 221 and the second winding 25 222 are connected in parallel, currents flowing in the first
winding 221 and the second winding 222 are different. Thus, a
current easily flows in the first winding 221 having low
electrical resistance. In general, a heat loss quantity
generated in a winding is proportional to a square of a current 30 value. Thus, a loss generated in the first winding 221 having
low electrical resistivity is larger than a loss generated in
the second winding 222. Accordingly, as described above, it is
preferable to collet preferable to collect first windings 221
generating large losses as many as possible in the first region
201 having high heat dissipation efficiency as described above.
[0036]
The electrical resistance of each first winding 221 is
RCu [Ω], the electrical resistivity of the first winding 221 is 5 ρCu [Ω∙m], and the diameter of the first winding 221 is φCu [mm].
The electrical resistance of each second winding 222 is RAl [Ω],
the electrical resistivity of the second winding 222 is ρAl
[Ω∙m], and the diameter of the second winding 222 is φAl [mm].
[0037] 10 The diameter φCu of the first winding 221 is preferably
lager than φAl × √(ρCu/ρAl). Accordingly, in the first region
201, a loss larger than a loss generated in the second winding
222 can be generated in the first winding 221. In this manner,
heat dissipation efficiency can be enhanced as described above. 15 [0038]
The electrical resistivity ρ [Ω∙m] of a coil is a
physical property value that represents the difficulty in a
current flow. The electrical resistance of the coil is
obtained by multiplying the electrical resistivity ρ by the 20 length L of the coil and then dividing the product by the
cross-sectional area S of the coil (i.e., ρ × L/S).
[0039]
In a case where the length L of the first winding 221 is
equal to the length L of the second winding 222 and the 25 diameter φCu of the first winding 221 is equal to the diameter
φAl of the second winding 222, the electrical resistance RAl [Ω]
of the second winding 222 is expressed by RCu × (ρAl/ρCu) [Ω].
[0040]
In a case where a current flowing in the coil 22 is 1 [A], 30 a current flowing in the first winding 221 is expressed by
ρAl/(ρAl + ρCu), and a current flowing in the second winding 222
is expressed by ρCu/(ρAl + ρCu). A loss generated in the first
winding 221 is expressed by RCu × (ρAl/(ρAl + ρCu))2 [W]. A loss
generated in the second winding 222 is expressed by RCu ×
(ρAl/ρCu) × (ρCu/(ρAl + ρCu))2 = RCu × ρCu × (ρAl/(ρAl + ρCu)2) [W].
[0041]
In a case where a loss generated in the first winding 221
is equal to a loss generated in the second winding 222, the 5 resistance [Ω] of the first winding 221 is expressed by RCu ×
(ρAl/ρCu) [Ω]. Supposing the cross-sectional area of one first
winding 221 is SCu, since the electrical resistance is
inversely proportional to the cross-sectional area of the
winding, in the case where a loss generated in the first 10 winding 221 is equal to a loss generated in the second winding
222, the resistance of the first winding 221 is expressed by
SCu × (ρCu/ρAl). In addition, in the case where a loss generated
in the first winding 221 is equal to a loss generated in the
second winding 222, the diameter φCu of the first winding 221 15 is expressed by φAl × √(ρCu/ρAl).
[0042]
Thus, if the diameter φCu [mm] of the first winding 221
is larger than φAl × √(ρCu/ρAl) (i.e., φAl × √(ρCu/ρAl) < φCu), in
the first region 201, a loss larger than a loss generated in 20 the second winding 222 can be generated in the first winding
221.
[0043]
For example, supposing the electrical resistivity ρCu of
the first winding 221 is 1.68 × 10−8 [Ω∙m] and the electrical 25 resistivity ρAl of the second winding 222 is 2.82 × 10−8 [Ω∙m],
the lower limit of the diameter φCu [mm] of the first winding
221 is 0.772 times as large as the diameter φAl [mm] of the
second winding 222. That is, if the diameter φCu of the first
winding 221 is 0.772 × φAl, the diameter of the first winding 30 221 is equal to the diameter of the second winding 222.
[0044]
If the diameter φCu of the first winding 221 is larger
than 0.772 × φAl (i.e., 0.772 × φAl < φCu), the electrical
resistance of the first winding 221 is lower than the
electrical resistance of the second winding 222. Accordingly,
in the first region 201, a loss larger than a loss generated in
the second winding 222 can be generated in the first winding
221. 5 [0045]
Thus, in the first region 201, if the stator 2 satisfies
(C1/S1) > (A1/S1) and the diameter φCu of the first winding 221
is larger than φAl × √(ρCu/ρAl), a temperature rise of the coil
22 can be reduced so that heat dissipation efficiency of the 10 stator 2 can be further enhanced.
[0046]
If the mechanical strength of the second winding 222 is
lower than the mechanical strength of the first winding 221,
the diameter φAl of the second winding 222 is preferably larger 15 than the diameter φCu of the first winding 221. Accordingly,
strength of the second winding 222 can be ensured in the
winding step.
[0047]
In addition, if the diameter φAl of the second winding 20 222 satisfies φCu ≤ φAl < φCu × √(ρAl/ρCu), a large loss is
generated in the first windings 221 collected in the first
region 201, and heat thereof can be efficiently dissipated from
the first region 201 to the heat dissipation path L1.
Furthermore, sufficiently high strength of the second winding 25 222 can be ensured in the winding step.
[0048]
In a process in which the coil 22 including the first
winding 221 and the second winding 222 arranged in parallel is
wound around the teeth 21b of the stator core 21, a common 30 winding machine is preferably used in order to avoid
complication of the process. On the other hand, in a case
where the diameters of the first winding 221 and the second
winding 222 are different, the nozzle diameter of a winding
nozzle of a winding machine is adjusted to a wider one of these
windings in general.
[0049]
In a case where the diameter φCu of the first winding 221
is larger than a double of the diameter φAl of the second 5 winding 222, two lines of a thin winding, that is, the second
winding 222, might be inserted in the winding nozzle so that
the second winding 222 might be damaged.
[0050]
Thus, the diameter φCu of the first winding 221 is 10 preferably smaller than a double of the diameter φAl of the
second winding 222. That is, the relationship between the
first winding 221 and the second winding 222 preferably
satisfies φAl × √(ρCu/ρAl) < φCu < φAl × 2. Accordingly, a large
loss is generated in the first winding 221 collected in the 15 first region 201, and heat of the first winding 221 is
effectively dissipated from the first region 201 to the heat
dissipation path L1, and damage and breakage of the second
winding 222 in the winding step can be avoided.
[0051] 20
The electric motor 1 described in the first embodiment is,
for example, an induction motor.
[0052]
In general, the induction motor is often driven without 25 using an inverter. That is, a controller for controlling the
electric motor 1 supplies a constant voltage to the coil 22 to
drive the electric motor 1 in many cases. Thus, variations in
load or supply voltage of the electric motor 1 significantly
increase a current flowing in the coil 22 so that the 30 temperature of the coil 22 might increase.
[0053]
The electric motor 1 including the stator 2 according to
the first embodiment has high heat dissipation efficiency as
described above and is capable of reducing a temperature rise
of the coil 22. Thus, especially large advantages can be
obtained in an induction motor in which a variation of a
current is large. The electric motor 1 may be an electric
motor except for an induction motor, such as a synchronous 5 motor. In this case, high heat dissipation efficiency can also
be obtained.
[0054]

[0055] 10 For example, in a case where windings having large heat
loss quantities are more densely disposed on the second side
than the first side of the coil-end part 22a, heat of the
stator 2 (e.g., heat of the stator core 21 and heat of the coil
22) is not easily transferred from the second side to the first 15 side. In this case, since heat of the stator 2 is not easily
dissipated to the outside of the stator 2, it is difficult to
reduce a temperature rise of the stator 2. Thus, heat of the
stator 2 is preferably dissipated to the heat dissipation path
L1 rather than the heat dissipation path L2. In a case where a 20 medium such as liquid (e.g., refrigerant) is present around the
coil 22, heat of the coil 22 can be easily dissipated to the
medium. In this case, heat of the coil 22 is more easily
dissipated to the heat dissipation path L1 than to the heat
dissipation path L2. Thus, the coil 22 is preferably formed 25 such that heat is easily dissipated to the heat dissipation
path L1.
[0056]
In the stator 2 according to this embodiment, the second
windings 222 are connected to the first windings 221 in 30 parallel, a larger number of the first windings 221 showing a
large heat loss quantity are disposed on the first side than on
the second side of the coil-end part 22a, and a larger number
of the second windings 222 showing a small heat loss quantity
are disposed on the second side than on the first side in the
coil-end part 22a. Specifically, the stator 2 satisfies (C1/S1)
> (C2/S2). That is, the density of the first windings 221 on
the first side of the coil-end part 22a, i.e., in the first
region 201, is larger than the density of the first windings 5 221 on the second side of the coil-end part 22a, i.e., in the
second region 202.
[0057]
Accordingly, the first windings 221 showing a large heat
loss quantity are densely arranged on the first side of the 10 coil-end part 22a. In this manner, heat of the stator 2,
especially heat of the coil 22, is efficiently transferred from
the second side to the first side of the coil-end part 22a and
is dissipated from the first side to the heat dissipation path
L1. Thus, heat dissipation efficiency in the coil-end part 22a 15 of the coil 22 can be enhanced, and a temperature rise in the
stator 2 (especially, the coil 22) at high-speed rotation of
the electric motor 1 can be reduced. Consequently, power of
the electric motor 1 including the stator 2 can be enhanced.
[0058] 20 In addition, the stator 2 preferably satisfies (C1/S1) >
(A1/S1). Accordingly, heat of the coil 22 is efficiently
dissipated from the first side to the heat dissipation path L1.
Thus, heat dissipation efficiency in the stator 2 can be
further enhanced, and a temperature rise in the stator 2 can be 25 reduced.
[0059]
In addition, the stator 2 preferably satisfies (C1/A1) >
(C2/A2). Accordingly, heat of the stator 2, especially heat of
the coil 22, is efficiently transferred from the second side to 30 the first side of the coil-end part 22a, and can be easily
dissipated from the first side to the heat dissipation path L1.
Consequently, heat dissipation efficiency in the stator 2 can
be further enhanced, and a temperature rise in the stator 2 can
be reduced.
[0060]
Only at least one first winding 221 may be disposed on
the first side of the coil-end part 22a. In this case, no
second winding 222 is present on the first side of the coil-end 5 part 22a. Accordingly, only the first winding 221 showing a
large heat loss quantity can be disposed on the first side of
the coil-end part 22a, that is, in the first region 201. Thus,
heat of the coil 22 can be easily dissipated from the first
side to the heat dissipation path L1. Consequently, heat 10 dissipation efficiency in the stator 2 can be further enhanced,
and a temperature rise in the stator 2 can be reduced.
[0061]
The stator 2 also preferably satisfies (CO1/SO1) >
(Ci1/Si1). Accordingly, many of the first windings 221 showing 15 large heat loss quantities can be disposed in a region of the
coil 22 exposed to the outside. That is, in the first region
201, many of the first windings 221 can be disposed outside the
region surrounded by the radius r. Consequently, heat
dissipation efficiency in the stator 2 can be further enhanced, 20 and a temperature rise in the stator 2 can be reduced.
[0062]
Since the first winding 221 and the second winding 222
are connected to each other in parallel, the values of currents
flowing in the first winding 221 and the second winding 222 are 25 different. Since the electrical resistance RCu of the first
winding 221 is lower than the electrical resistance RAl of the
second winding 222, a current easily flows in the first winding
221 having low electrical resistance. Accordingly, a heat loss
quantity generated in the first winding 221 is larger than a 30 heat loss quantity generated in the second winding 222. Thus,
as described above, many of the first windings 221 are arranged
in the first region 201 so that heat dissipation efficiency in
the coil-end part 22a can be enhanced.
[0063]
In a case where the diameter φCu of the first winding 221
is larger than φAl × √(ρCu/ρAl), a loss larger than a loss
generated in the second winding 222 can be generated in the
first winding 221 in the first region 201. In this manner, 5 heat dissipation efficiency can be enhanced as described above.
[0064]
A relationship between the first winding 221 and the
second winding 222 preferably satisfies φAl × √(ρCu/ρAl) < φCu <
φAl × 2. Accordingly, a large loss is generated in the first 10 winding 221 collected in the first region 201, and heat of the
first winding 221 is effectively dissipated from the first
region 201 to the heat dissipation path L1, and damage and
breakage of the second winding 222 in the winding step can be
avoided. 15 [0065]
In addition, in a case where the relationship between the
first winding 221 and the second winding 222 satisfies φAl ×
√(ρCu/ρAl) < φCu < φAl, a large loss is generated in the first
winding 221 collected in the first region 201, and heat thereof 20 can be efficiently dissipated from the first region 201 to the
heat dissipation path L1. Furthermore, sufficiently high
strength of the second winding 222 can be ensured in the
winding step.
[0066] 25 The electric motor 1 including the stator 2 according to
the first embodiment has advantages of the stator 2 described
above. In addition, application of the electric motor 1
including the stator 2 according to the first embodiment
provides especially high advantages. 30 [0067]
SECOND EMBODIMENT

Next, a scroll compressor 300 as a compressor to which
the electric motor 1 described in the first embodiment is
applied will be described.
FIG. 6 is a cross-sectional view illustrating the scroll
compressor 300.
[0068] 5 The scroll compressor 300 includes a closed container 307,
a compressor mechanism 305 disposed in the closed container 307,
an electric motor 1 for driving the compressor mechanism 305, a
shaft 306 for coupling the compressor mechanism 305 and the
electric motor 1 to each other, and a subframe 308 supporting 10 the lower end of the shaft 306 (i.e., an opposite end from the
compressor mechanism 305).
[0069]
The compressor mechanism 305 includes a fixed scroll 301
having a spiral portion, a swing scroll 302 having a spiral 15 portion forming a compression chamber between the spiral
portion of the swing scroll 302 and the spiral portion of the
fixed scroll 301, a compliance frame 303 holding the upper end
of the shaft 306, and a guide frame 304 fixed to the closed
container 307 and holding the compliance frame 303. 20 [0070]
A suction pipe 310 penetrating the closed container 307
is press fitted in the fixed scroll 301. The closed container
307 is provided with a discharge pipe 311 that discharges a
high-pressure refrigerant gas discharged from the fixed scroll 25 301, to the outside. The discharge pipe 311 communicates with
an opening (not shown) disposed between the compressor
mechanism 305 of the closed container 307 and the electric
motor 1.
[0071] 30 The electric motor 1 is fixed to the closed container 307
by fitting the stator 2 in the closed container 307. The
configuration of the electric motor 1 has been described above.
To the closed container 307, a glass terminal 309 for supplying
electric power to the electric motor 1 is fixed by welding.
[0072]
When the electric motor 1 rotates, this rotation is
transferred to the swing scroll 302, and the swing scroll 302
swings. When the swing scroll 302 swings, the volume of the 5 compression chamber formed by the spiral portion of the swing
scroll 302 and the spiral portion of the fixed scroll 301
changes. Then, a refrigerant gas is sucked through the suction
pipe 310, compressed, and then discharged from the discharge
pipe 311. 10 [0073]
While the electric motor 1 rotates, a current flows in
the coil 22, and heat is generated in the coil 22. Heat
generated in the coil 22 is dissipated to the outside of the
stator 2 as described in the first embodiment. 15 [0074]
The scroll compressor 300 includes the electric motor 1
described in the first embodiment, and thus, has advantages
described in the first embodiment. In addition, since the
electric motor 1 including the stator 2 according to the first 20 embodiment has high heat dissipation efficiency, a temperature
rise in the scroll compressor 300 can be reduced. In addition,
as described in the first embodiment, since power of the
electric motor 1 can be enhanced, power of the scroll
compressor 300 can also be enhanced. 25 [0075]
The electric motor 1 described in the first embodiment
may be applied to a compressor except for the scroll compressor
300.
[0076] 30 THIRD EMBODIMENT

Next, an air conditioner 400 to which the electric motor
1 described in the first embodiment is applied will be
described.
FIG. 7 is a diagram illustrating the air conditioner 400
(also referred to as a refrigeration cycle apparatus).
[0077]
The air conditioner 400 includes a compressor 401, a 5 condenser 402, a throttling device (also referred to as a
decompressor) 403, and an evaporator 404. The compressor 401,
the condenser 402, the throttling device 403, and the
evaporator 404 are coupled to one another by a refrigerant pipe
407 to thereby constitute a refrigeration cycle. That is, a 10 refrigerant circulates in the compressor 401, the condenser 402,
the throttling device 403, and the evaporator 404 in this order.
[0078]
The compressor 401, the condenser 402, and the throttling
device 403 are provided in an outdoor unit 410. The compressor 15 401 is the scroll compressor 300 described in the second
embodiment. Alternatively, the compressor 401 may be a
compressor except for the scroll compressor as long as the
compressor 401 includes the electric motor 1 including the
stator 2 described in the first embodiment. The outdoor unit 20 410 includes an outdoor-side fan 405 for supplying outdoor air
to the condenser 402. The evaporator 404 is disposed in an
indoor unit 420. The indoor unit 420 includes an indoor-side
fan 406 for supplying indoor air to the evaporator 404.
[0079] 25 An example of operation of the air conditioner 400 will
be described. The compressor 401 compresses a sucked
refrigerant and sends the compressed refrigerant. The
condenser 402 performs heat exchange between the refrigerant
that flowed from the compressor 401 and outdoor air, condenses 30 the refrigerant to liquefy the refrigerant, and sends the
resulting refrigerant to the refrigerant pipe 407. The
outdoor-side fan 405 supplies outdoor air to the condenser 402.
The throttling device 403 adjusts, for example, the pressure of
the refrigerant flowing in the refrigerant pipe 407 by
adjusting the opening degree of the throttling device 403.
[0080]
The evaporator 404 performs heat exchange between the
refrigerant changed to a low-pressure state by the throttling 5 device 403 and indoor air, causes the refrigerant to take heat
from the air to vaporize the refrigerant, and sends the
resulting refrigerant to the refrigerant pipe 407. The indoorside
fan 406 supplies indoor air to the evaporator 404.
Accordingly, cold air from which heat has been taken by the 10 evaporator 404 is supplied into the room.
[0081]
The air conditioner 400 includes the electric motor 1
described in the first embodiment, and thus, has advantages
described in the first embodiment. In addition, the air 15 conditioner 400 includes, as the compressor 401, the scroll
compressor 300 described in the second embodiment, and thus,
has advantages described in the second embodiment. As
described above, since the electric motor 1 described in the
first embodiment has high heat dissipation efficiency, a 20 temperature rise in the compressor 401 can be reduced so that a
stable operation of the air conditioner 400 can be thereby
achieved. In addition, with an increase in power of the
compressor 401 achieved by an increase in power of the electric
motor 1, power of the air conditioner 400 can also be increased. 25 [0082]
Although the preferred embodiments of the present
invention have been described above, the present invention is
not limited to the embodiments, and various modifications and
changes can be made within the gist of the present invention. 30 DESCRIPTION OF REFERENCE CHARACTERS
[0083]
1 electric motor, 2 stator, 3 rotor, 21 stator core, 21a
yoke, 21b tooth, 22 coil, 22a coil-end part, 201 first region,
202 second region, 221 first winding, 222 second winding, 300
scroll compressor (compressor), 305 compressor mechanism, 307
closed container, 400 air conditioner, 401 compressor, 402
condenser, 403 throttling device (decompressor), 404 evaporator.

We Claim:
1. A stator comprising:
a stator core; and 5 a coil wound around the stator core and including at
least one first winding and at least one second winding
connected to the at least one first winding in parallel, the at
least one second winding being formed of a material different
from the at least one first winding, wherein 10 the coil includes a coil-end part located outside the
stator core, and
the stator satisfies:
(C1/S1) > (C2/S2)
where P1 is a straight line that halves a maximum height 15 of the coil-end part from a point of contact of the coil with
the stator core in the coil-end part, S1 is a total crosssectional
area on a first side of the coil-end part that is an
opposite side of the straight line P1 from the stator core, S2
is a total cross-sectional area on a second side of the coil- 20 end part that is an opposite side of the straight line P1 from
the first side, C1 is a total cross-sectional area of the at
least one first winding on the first side of the coil-end part,
and C2 is a total cross-sectional area of the at least one
first winding on the second side of the coil-end part. 25
2. The stator according to claim 1, wherein
the stator satisfies:
(C1/S1) > (A1/S1)
where A1 is a total cross-sectional area of the at least 30 one second winding disposed on the first side of the coil-end
part.
3. The stator according to claim 1 or 2, wherein
the stator satisfies:
(C1/A1) > (C2/A2)
where A1 is a total cross-sectional area of the at least
one second winding disposed on the first side of the coil-end
part and A2 is a total cross-sectional area of the at least one 5 second winding disposed on the second side of the coil-end part.
4. The stator according to claim 1, wherein only the at
least one first winding is disposed on the first side of the
coil-end part.
5. The stator according to any one of claims 1 to 4, wherein
the stator satisfies:
(CO1/SO1) > (Ci1/Si1)
where P2 is a straight line that halves the straight line 15 P1 on a cross section of the coil-end part, r is a radius about
an intersection point of the straight line P1 and the straight
line P2 on the cross section of the coil-end part, the radius r is smaller than each of a half of a length of the straight line P1 and a half of a length of the straight line P2 on the cross 20 section of the coil-end part, SO1 is a total cross-sectional area of a portion located outside a region surrounded by the
radius r on the first side of the coil-end part, Si1 is a total cross-sectional area of the region surrounded by the radius ron the first side of the coil-end part, CO1/SO1 is a ratio of 25 the at least one first winding to the total cross-sectional area SO1, and Ci1/Si1 is a ratio of the at least one first winding to the total cross-sectional area Si1.
6. The stator according to any one of claims 1 to 5, wherein 30 the stator satisfies:
[Eq. 1]
where φCu [mm] is a diameter of the first winding, φAl
[mm] is a diameter of the second winding, ρCu [Ω∙m] is
electrical resistivity of the first winding, and ρAl [Ω∙m] is
electrical resistivity of the second winding.
7. The stator according to any one of claims 1 to 5, wherein 5 the stator satisfies:
[Eq. 2]
where φCu [mm] is a diameter of the first winding, φAl
[mm] is a diameter of the second winding, ρCu [Ω∙m] is
electrical resistivity of the first winding, and ρAl [Ω∙m] is 10 electrical resistivity of the second winding.
8. The stator according to any one of claims 1 to 7, wherein
the at least one first winding is a copper wire.
9. The stator according to any one of claims 1 to 8, wherein
the at least one second winding is an aluminum wire.
10. An electric motor comprising:
the stator according to any one of claims 1 to 9; and 20 a rotor rotatably disposed inside the stator.
11. The electric motor according to claim 10, wherein the
electric motor is an induction motor.
12. A compressor comprising:
a closed container;
a compressor mechanism disposed in the closed container; and the electric motor according to claim 10 or 11 to drive 30 the compressor mechanism.
13. An air conditioner comprising:
the compressor according to claim 12;
a condenser;a decompressor; and an evaporator.