FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
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 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION
AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
TECHNICAL 5 FIELD
[0001]
The present invention relates to a motor, a compressor,
and an air conditioner.
BACKGROUND ART
10 [0002]
A stator of a motor includes a stator core having a
plurality of teeth around which a coil is wound. A slot that
houses the coil therein is formed between adjacent teeth of the
stator core. Recently, in order to increase an area of the slot,
15 a configuration in which a width of the tooth is narrowed at an
end portion of the stator core in the axial direction is proposed
(see, for example, Patent References 1 to 4).
PRIOR ART REFERENCE
PATENT REFERENCE
20 [0003]
[Patent Reference 1] Japanese Patent Application
Publication No. 2017-103850 (see FIG. 1)
[Patent Reference 2] Japanese Patent Application
Publication No. 2015-171249 (see FIG. 3)
25 [Patent Reference 3] Japanese Patent Application
Publication No. 2017-99044 (see FIG. 5)
[Patent Reference 4] Japanese Patent Application
Publication No. 2017-17784 (see FIG. 2)
SUMMARY OF THE INVENTION
30 PROBLEM TO BE SOLVED BY THE INVENTION
[0004]
A magnetic flux from the rotor flows into the tooth, and a
magnetic flux density tends to be high in the tooth having a
narrow width. When the magnetic flux density is saturated in the
3
tooth having the narrow width, part of the magnetic flux flows in
the axial direction in the stator core. Consequently, the
magnetic flux flows in a direction perpendicular to sheet
surfaces of steel laminations constituting the stator core. Thus,
eddy current is generated, and causes reduction 5 in the motor
efficiency due to eddy current loss (iron loss).
[0005]
The present invention is intended to solve the abovedescribed
problems, and an object of the present invention is to
10 reduce eddy current loss in a motor.
MEANS OF SOLVING THE PROBLEM
[0006]
A motor of the present invention includes a rotor
rotatable about a rotation axis, and a stator provided so as to
15 surround the rotor. The rotor has a rotor core having steel
laminations stacked in an axial direction of the rotation axis
and a permanent magnet embedded in the rotor core. The stator
has a stator core having steel laminations stacked in the axial
direction and a coil wound on the stator core. The stator core
20 has a slot in which the coil is housed. The stator core has a
first core portion at an end portion of the stator core in the
axial direction and a second core portion at a center portion of
the stator core in the axial direction. An area of the slot is
larger in the first core portion than in the second core portion.
25 A sheet thickness T0 and a lamination gap L0 of the steel
laminations of the rotor core and a sheet thickness T1 and a
lamination gap L1 of the steel laminations of the first core
portion of the stator core satisfy at least one of T0 > T1 and L0
< L1.
30 EFFECTS OF THE INVENTION
[0007]
According to the present invention, at least one of T0 >
T1 and L0 < L1 is satisfied, and thus the magnetic flux flowing
in the axial direction in the stator core is reduced. This
4
suppresses generation of eddy current, and thus the eddy current
loss (iron loss) can be reduced and the motor efficiency can be
enhanced.
BRIEF DESCRIPTION OF THE DRAWINGS
5 [0008]
FIG. 1 is a cross-sectional view showing a motor of a
first embodiment.
FIG. 2 is a cross-sectional view showing a second core
portion of the first embodiment.
10 FIG. 3 is an enlarged cross-sectional view showing a part
of the second core portion of the first embodiment.
FIG. 4 is a cross-sectional view showing a first core
portion of the first embodiment.
FIG. 5 is an enlarged cross-sectional view showing a part
15 of the first core portion of the first embodiment.
FIG. 6(A) is a perspective view showing a part of a stator
core of the first embodiment, and FIG. 6(B) is a perspective view
showing a state where insulators and insulating films are
attached to the stator core.
20 FIG. 7(A) is a diagram showing cross-sectional structures
of a tooth, the insulators, and the insulating films of the first
embodiment, and FIG. 7(B) is a diagram showing cross-sectional
structures of those in Comparative Example for comparison.
FIG. 8 is a longitudinal-sectional view showing the motor
25 of the first embodiment.
FIGS. 9(A) and 9(B) are a plan view and a cross-sectional
view for explaining a V-shaped crimping portion.
FIGS. 10(A) and 10(B) are a plan view and a crosssectional
view for explaining a circular crimping portion.
30 FIG. 11 is a longitudinal-sectional view showing a motor
of Comparative Example.
FIG. 12 is a schematic diagram for explaining generation
of eddy current in a steel lamination.
FIG. 13 is a graph showing a relationship between a motor
5
efficiency and a difference L1 - L0 between lamination gaps of
the steel laminations.
FIG. 14 is a longitudinal-sectional view showing a motor
of a second embodiment.
FIG. 15 is a longitudinal-sectional view 5 showing a motor
of a third embodiment.
FIG. 16 is a graph showing a relationship between a motor
efficiency and a difference T0 - T1 between sheet thicknesses of
the steel laminations.
10 FIG. 17 is a longitudinal-sectional view showing a motor
of a fourth embodiment.
FIG. 18 is a longitudinal-sectional view showing a motor
of a fifth embodiment.
FIG. 19 is a longitudinal-sectional view showing another
15 configuration example of the motor of the fifth embodiment.
FIG. 20 is a cross-sectional view showing a rotary
compressor to which the motor of each embodiment is applicable.
FIG. 21 is a diagram showing an air conditioner that
includes the rotary compressor in FIG. 20.
20 MODE FOR CARRYING OUT THE INVENTION
[0009]
FIRST EMBODIMENT
(Configuration of Motor)
A motor 100 of a first embodiment of the present invention
25 will be described. FIG. 1 is a cross-sectional view showing the
motor 100 of the first embodiment of the present invention. The
motor 100 is a permanent magnet embedded motor in which permanent
magnets 53 are embedded in a rotor 5. The motor 100 is used in,
for example, a rotary compressor 300 (FIG. 20).
30 [0010]
The motor 100 is a motor called an inner-rotor type, and
includes a stator 1 and the rotor 5 rotatably provided on an
inner side of the stator 1. An air gap of, for example, 0.3 to
1.0 mm is formed between the stator 1 and the rotor 5.
6
[0011]
Hereinafter, a direction of a center axis C1 which is a
rotation axis of the rotor 5 is simply referred to as an “axial
direction”. A circumferential direction about the center axis C1
(indicated by an arrow R1 in FIG. 1) is simply 5 referred to as a
“circumferential direction”. A radial direction about the center
axis C1 is simply referred to as a “radial direction”. FIG. 1 is
a cross-sectional view on a plane perpendicular to the center
axis C1.
10 [0012]
(Configuration of Rotor)
The rotor 5 has a cylindrical rotor core 50, permanent
magnets 53 embedded in the rotor core 50, and a shaft 58 fixed to
a center portion of the rotor core 50. The shaft 58 is, for
15 example, a shaft of the compressor 300 (FIG. 20).
[0013]
The rotor core 50 is composed of steel laminations 501
(FIG. 8) which are stacked in the axial direction and integrated
together by crimping or the like. Each of the steel laminations
20 501 is, for example, an electromagnetic steel sheet. A sheet
thickness of each of the steel laminations 501 and a lamination
gap between the steel laminations 501 will be described later.
[0014]
A plurality of magnet insertion holes 51 into which the
25 permanent magnets 53 are inserted are formed along an outer
circumferential surface of the rotor core 50. Each magnet
insertion hole 51 is a through hole passing through the rotor
core 50 in the axial direction. The number of magnet insertion
holes 51 is six in this example. However, the number of magnet
30 insertion holes 51 is not limited to six, and it is sufficient
that the number of magnet insertion holes 51 is two or more.
Each magnet insertion hole 51 corresponds to one magnetic pole.
A region between adjacent magnet insertion holes 51 corresponds
to an inter-polar portion.
7
[0015]
The magnet insertion hole 51 is formed in a V shape such
that a center portion of the magnet insertion hole 51 in the
circumferential direction protrudes most toward the center axis
C1. In each magnet insertion hole 51, two permanent 5 magnets 53
are disposed on both sides of the center portion of the magnet
insertion hole 51 in the circumferential direction. The two
permanent magnets 53 in the magnet insertion hole 51 are
magnetized so that pole-faces of the same polarity face the outer
10 side in the radial direction.
[0016]
Each permanent magnet 53 is a flat-plate member elongated
in the axial direction and has a width in the circumferential
direction of the rotor core 50 and a thickness in the radial
15 direction of the rotor core 50. The thickness of the permanent
magnet 53 is, for example, 2 mm. The permanent magnet 53 is
formed of a rare earth magnet that contains, for example,
neodymium (Nd), iron (Fe) and boron (B) as main components. The
permanent magnet 53 is magnetized in the thickness direction.
20 [0017]
Although two permanent magnets 53 are disposed in each
magnet insertion hole 51 in this example, it is also possible to
dispose one permanent magnet 53 in each magnet insertion hole 51.
In this case, the magnet insertion hole 51 is not formed in the V
25 shape as described above, but is formed linearly.
[0018]
A flux barrier (a leakage flux suppression hole) 52 is
formed on each of both ends of the magnet insertion hole 51 in
the circumferential direction. The flux barrier 52 is provided
30 for suppressing leakage magnetic flux between adjacent magnetic
poles. A core portion between the flux barrier 52 and the outer
circumference of the rotor core 50 is a thin-walled portion for
suppressing short circuit of the magnetic flux between the
adjacent magnetic poles. A thickness of the thin-walled portion
8
is desirably the same as the thickness of each of the steel
laminations 501 of the rotor core 50.
[0019]
(Configuration of Stator)
The stator 1 includes a stator core 10 5 and a coil 4 wound
on the stator core 10. The stator core 10 has a yoke 11 having
an annular shape about the center axis C1 and a plurality of
teeth 12 extending inward in the radial direction (i.e., in a
direction toward the center axis C1) from the yoke 11. A tooth
10 end portion 13 facing the outer circumferential surface of the
rotor 5 is formed at an inner end portion of the tooth 12 in the
radial direction.
[0020]
In this example, nine teeth 12 are arranged at equal
15 intervals in the circumferential direction, but it is sufficient
that the number of teeth 12 is three or more. A slot 14, which
is a space for housing the coil 4, is formed between the teeth 12
adjacent to each other in the circumferential direction.
[0021]
20 The stator core 10 has a configuration in which a
plurality (nine in this example) of split cores 9, each including
one tooth 12, are connected together in an annular shape. These
split cores 9 are connected to each other at split surface
portions 15 each of which is formed in the yoke 11 at a midpoint
25 between the two adjacent teeth 12. More specifically, the
adjacent split cores 9 are connected to each other by joint wraps
or plastically deformable thin-walled portions (not shown)
provided on the outer circumferential side of the split surface
portions 15.
30 [0022]
The coil 4 is obtained by winding a magnet wire around the
teeth 12 via insulators 2 and insulating films 3 (FIG. 6(B)). A
wire diameter of the coil 4 is, for example, 1.0 mm. The coil 4
is wound around each tooth 12, for example, 80 turns in a
9
concentrated winding manner. The coil 4 has coil portions of
three phases which are connected in Y connection. The wire
diameter and the number of turns of the coil 4 are determined
according to a required number of rotations, a required torque,
an applied voltage, or an area of the slot 14. 5 In a process in
which the coil 4 is wound on the stator core 10, the split cores
9 of the stator core 10 are unfolded into a strip shape, and thus
a winding operation of the coil 4 is facilitated.
[0023]
10 As shown in FIG. 8 described later, the stator core 10 has
a first core portion 10A at each of both end portions of the
stator core 10 in the axial direction and a second core portion
10B at a center portion of the stator core 10 in the axial
direction. In this regard, the first core portion 10A is not
15 necessarily provided at each of both end portions of the stator
core 10 in the axial direction, but it is sufficient that the
first core portion 10A is provided at least at one end portion of
the stator core 10 in the axial direction.
[0024]
20 FIG. 2 is a plan view showing the second core portion 10B.
The second core portion 10B is composed of steel laminations 101
which are stacked in the axial direction and integrated together
by crimping or the like. Each of the steel laminations 101 is,
for example, an electromagnetic steel sheet. A sheet thickness
25 of each of the steel laminations 101 and a lamination gap between
the steel laminations 101 will be described later.
[0025]
The second core portion 10B has an annular second yoke
portion 11B and a plurality of second tooth portions 12B
30 extending inward in the radial direction from the second yoke
portion 11B. The number of second tooth portions 12B is nine in
this example. The second tooth portion 12B has a second tooth
end portion 13B at its inner end in the radial direction. The
second tooth end portion 13B has a width wider than widths of
10
other portions of the second tooth portion 12B.
[0026]
The second core portion 10B has a configuration in which a
plurality of split cores 9B each including one second tooth
portion 12B are connected together in an annular 5 shape at the
above-described split surface portions 15.
[0027]
FIG. 3 is a diagram showing one split core 9B of the
second core portion 10B. The second yoke portion 11B has an
10 outer circumferential surface 110 on the outer side in the radial
direction and an inner circumferential surface 111B on the inner
side in the radial direction. The second tooth portion 12B has
side surfaces 121B on both sides in the circumferential direction.
The second tooth end portion 13B has an end surface 130 facing
15 the rotor 5 and outer circumferential surfaces 131B on the outer
side in the radial direction.
[0028]
The inner circumferential surface 111B of the second yoke
portion 11B, the side surface 121B of the second tooth portion
20 12B, and the outer circumferential surface 131B of the second
tooth end portion 13B face the slot 14.
[0029]
A concave portion 19 is formed on the outer
circumferential surface 110 of the second yoke portion 11B. The
25 concave portion 19 is a portion with which a jig for holding the
stator core 10 is engaged during the winding operation of the
coil 4. Further, the concave portion 19 is a portion serving as
a refrigerant flow path in a state where the motor 100 is mounted
in the compressor. The concave portion 19 is located, for
30 example, on a straight line in the radial direction that passes
through a center of the second tooth portion 12B in the width
direction.
[0030]
A fixing hole 16 into which a protrusion 26 (FIG. 6(B)) of
11
the insulator 2 described later is press-fitted is formed in the
second yoke portion 11B. The fixing hole 16 is located on a
straight line in the radial direction that passes through the
center of the second tooth portion 12B in the width direction,
but is not limited to this position. A cross-5 sectional shape of
the fixing hole 16 is a semicircular shape in this example, but
is not limited to the semicircular shape.
[0031]
The second yoke portion 11B has crimping portions 17 and
10 18 for fixing the steel laminations 101 of the second core
portion 10B to each other. The crimping portion 17 is formed on
the inner side of the fixing hole 16 in the radial direction.
Two crimping portions 18 are formed one on each side of the
fixing hole 16 in the circumferential direction. The positions
15 of the crimping portions 17 and 18 are not limited to these
positions. The crimping portion 17 is a circular crimping
portion (see FIGS. 10(A) and 10(B)), and the crimping portion 18
is a V-shaped crimping portion (see FIGS. 9(A) and 9(B)).
However, the crimping portion 17 is not limited to the circular
20 crimping portion, and the crimping portion 18 is not limited to
the V-shaped crimping portion.
[0032]
FIG. 4 is a plan view showing the first core portion 10A.
The first core portion 10A is composed of steel laminations 101
25 which are stacked in the axial direction and integrated together
by crimping or the like. Each of the steel laminations 101 is,
for example, an electromagnetic steel sheet. A sheet thickness
of each of the steel laminations 101 and a lamination gap between
the steel laminations 101 will be described later.
30 [0033]
The first core portion 10A has an annular first yoke
portion 11A and a plurality of first tooth portions 12A extending
inward in the radial direction from the first yoke portion 11A.
The number of first tooth portions 12A is nine in this example.
12
The first tooth portion 12A has a first tooth end portion 13A at
its inner end in the radial direction. The first tooth end
portion 13A has a width wider than widths of other portions of
the first tooth portion 12A.
5 [0034]
The first core portion 10A has a configuration in which a
plurality of split cores 9A each including one first tooth
portion 12A are connected together in an annular shape at the
above-described split surface portions 15.
10 [0035]
FIG. 5 is a diagram showing one split core 9A of the first
core portion 10A. In FIG. 5, an outline of the split core 9B
(FIG. 3) of the second core portion 10B is shown by a dashed line.
The first yoke portion 11A has an outer circumferential surface
15 110 on the outer side in the radial direction and an inner
circumferential surface 111A on the inner side in the radial
direction. The first tooth portion 12A has side surfaces 121A on
both sides in the circumferential direction. The first tooth end
portion 13A has an end surface 130 facing the rotor 5 and outer
20 circumferential surfaces 131A on the outer side in the radial
direction.
[0036]
The inner circumferential surface 111A of the first yoke
portion 11A, the side surface 121A of the first tooth portion 12A,
25 and the outer circumferential surface 131A of the first tooth end
portion 13A all face the slot 14.
[0037]
The inner circumferential surface 111A of the first yoke
portion 11A is located on the outer side in the radial direction
30 with respect to the inner circumferential surface 111B of the
second yoke portion 11B. The side surfaces 121A of the first
tooth portion 12A are located on the inner side in the width
direction (circumferential direction) with respect to the side
surfaces 121B of the second tooth portion 12B. The outer
13
circumferential surfaces 131A of the first tooth end portion 13A
are located on the inner side in the radial direction with
respect to the outer circumferential surfaces 131B of the second
tooth end portion 13B.
5 [0038]
That is, the inner circumferential surface 111A of the
first yoke portion 11A, the side surfaces 121A of the first tooth
portion 12A, and the outer circumferential surfaces 131A of the
first tooth end portion 13A are located at positions displaced in
10 directions to increase the area of the slot 14.
[0039]
Thus, a step portion 125 is formed in each of a portion
adjacent to the inner circumferential surface 111A of the first
yoke portion 11A, portions adjacent to the side surfaces 121A of
15 the first tooth portion 12A, and portions adjacent to the outer
circumferential surfaces 131A of the first tooth end portion 13A.
In other words, the step portion 125 facing the slot 14 is formed.
[0040]
The step portion 125 is not limited to such an arrangement.
20 It is sufficient that at least one of the inner circumferential
surface 111A of the first yoke portion 11A, the side surfaces
121A of the first tooth portion 12A, and the outer
circumferential surfaces 131A of the first tooth end portion 13A
(for example, the side surface 121A of the first tooth portion
25 12A) is displaced in the direction to increase the area of the
slot 14, and the step portion 125 is provided at the displaced
portion.
[0041]
The outer circumferential surface 110 of the first yoke
30 portion 11A is aligned with the outer circumferential surface 110
of the second yoke portion 11B (FIG. 3). The end surface 130 of
the first tooth end portion 13A is aligned with the end surface
130 of the second tooth end portion 13B (FIG. 3).
[0042]
14
The fixing holes 16, the crimping portions 17 and 18, and
the concave portions 19 are formed in the first yoke portion 11A.
The arrangement and shapes of the fixing holes 16, the crimping
portions 17 and 18, and the concave portions 19 are the same as
those formed in the second yoke portion 5 11B (FIG. 3).
[0043]
FIG. 6(A) is a perspective view showing the stator core 10
(split core 9). As described above, the step portion 125 is
formed in each of the portion adjacent to the inner
10 circumferential surface 111A of the first yoke portion 11A, the
portions adjacent to the side surfaces 121A of the first tooth
portion 12A, and the portions adjacent to the outer
circumferential surfaces 131A of the first tooth end portion 13A.
The step portion 125 is a portion with which the insulator 2
15 described next is engaged.
[0044]
FIG. 6(B) is a perspective view showing a state in which
the insulators 2 and the insulating films 3 are attached to the
stator core 10. One insulator 2 is attached to each of both end
20 portions of the stator core 10 in the axial direction (i.e., the
first core portions 10A). The insulator 2 is formed of, for
example, a resin such as polybutylene terephthalate (PBT).
[0045]
Each insulator 2 has a wall portion 25 attached to the
25 yoke 11, a body portion 22 attached to the tooth 12, and a flange
portion 21 attached to the tooth end portion 13. The flange
portion 21 and the wall portion 25 face each other in the radial
direction with the body portion 22 interposed therebetween.
[0046]
30 The coil 4 is wound around the body portion 22. The flange
portion 21 and the wall portion 25 guide the coil 4, which is
wound around the body portion 22, from both sides in the radial
direction. Each of the flange portion 21 and the wall portion 25
may be provided with a step 23 for positioning the coil 4 wound
15
around the body portion 22.
[0047]
The protrusion 26 (shown by a dashed line in FIG. 6(B)) is
formed on the wall portion 25 of the insulator 2, and the
protrusion 26 is press-fitted into the fixing hole 5 16 (FIG. 6(A))
of the stator core 10. The protrusion 26 protrudes in the axial
direction and has a semicircular cross section. The crosssectional
shape of the protrusion 26 is not limited to a
semicircular shape, and it is sufficient that the protrusion 26
10 has a cross-sectional shape corresponding to the fixing hole 16.
[0048]
The insulating films 3 are attached to the surfaces of the
second core portion 10B on the slot 14 side in the stator core 10.
Each insulating film 3 is formed of a resin such as polyethylene
15 terephthalate (PET). Each insulating film 3 covers the inner
circumferential surface 111B of the second yoke portion 11B, the
side surface 121B of the second tooth portion 12B, and the outer
circumferential surface 131B (FIG. 6(A)) of the second tooth end
portion 13B.
20 [0049]
The insulator 2 and the insulating film 3 electrically
insulate the stator core 10 from the coil 4 in the slot 14.
[0050]
FIG. 7(A) is a cross-sectional view on a plane
25 perpendicular to the radial direction showing the tooth 12 and
the insulators 2 and the insulating films 3 surrounding the tooth
12. As described above, the step portions 125 are formed on both
sides of the first tooth portion 12A in the circumferential
direction. Each insulator 2 is engaged with the step portion 125
30 and is thereby attached to the end portion of the tooth 12 in the
axial direction. As described above, the step portions 125 are
also formed on the inner side in the circumferential direction of
the inner circumferential surface 111A of the first yoke portion
11A (FIG. 6(A)) and on the outer side in the radial direction of
16
the outer circumferential surface 131A of the first tooth end
portion 13A (FIG. 6(A)).
[0051]
With such a configuration, each insulator 2 is attached to
the tooth 12 so as not to protrude from the tooth 5 12 to the slot
14 side. Thus, the area of the slot 14 can be increased, and
thus the number of turns of the coil 4 can be increased.
[0052]
FIG. 7(B) is a cross-sectional view corresponding to FIG.
10 7(A), showing the tooth 12 and the insulators 200 in Comparative
Example. In Comparative Example, the tooth 12 has a rectangular
sectional shape, and the insulators 200 are provided to surround
the tooth 12 from both ends in the axial direction and both ends
in the circumferential direction (i.e., both side surfaces). In
15 Comparative Example, each insulator 200 protrudes to the slot 14
side, and thus the area of the slot 14 is smaller than in the
configuration shown in FIG. 7(A).
[0053]
(Configuration for Reducing Eddy Current Loss)
20 Next, a configuration for reducing eddy current loss will
be described. FIG. 8 is a longitudinal-sectional view showing
the motor 100. As described above, the stator core 10 is
obtained by stacking a plurality of steel laminations 101 in the
axial direction, and the rotor core 50 is obtained by stacking a
25 plurality of steel laminations 501 in the axial direction. The
stator core 10 and the rotor core 50 have the same length in the
axial direction. In FIG. 8, the thicknesses of the steel
laminations 101 and 501 are shown to be thick for convenience of
illustration.
30 [0054]
The sheet thickness T0 and the lamination gap L0 of the
steel laminations 501 are both constant throughout the entire
area of the rotor core 50 in the axial direction. The sheet
thickness T0 refers to a thickness of each of the steel
17
laminations 501. The lamination gap L0 refers to an interval
(gap) between two steel laminations 501 overlapping each other in
the axial direction.
[0055]
The sheet thickness T0 of each of the 5 steel laminations
501 of the rotor core 50 is, for example, 0.1 to 0.7 mm (for
example, 0.35 mm). When the sheet thickness T0 is 0.35 mm, the
lamination gap L0 is, for example, 0.003 mm.
[0056]
10 The sheet thickness T1 and the lamination gap L1 of the
steel laminations 101 of the stator core 10 are both constant
throughout the entire area of the stator core 10 in the axial
direction. The sheet thickness T1 refers to a thickness of each
of the steel laminations 101. The lamination gap L1 refers to an
15 interval (gap) between two steel laminations 101 overlapping each
other in the axial direction.
[0057]
The sheet thickness T1 of each of the steel laminations
101 is, for example, 0.1 to 0.7 mm (for example, 0.35 mm). When
20 the sheet thickness T1 of each of the steel laminations 101 is
0.35 mm, the lamination gap L1 is, for example, 0.01 mm.
[0058]
For example, when the length of the stator core 10 in the
axial direction is 45 mm, the length of the first core portion
25 10A in the axial direction is 5 mm, while the length of the
second core portion 10B in the axial direction is 35 mm.
[0059]
In the first embodiment, the sheet thickness T0 of each of
the steel laminations 501 of the rotor core 50 and the sheet
30 thickness T1 of each of the steel laminations 101 of the stator
core 10 are the same. Meanwhile, the lamination gap L0 of the
steel laminations 501 of the rotor core 50 and the lamination gap
L1 of the steel laminations 101 of the stator core 10 satisfy a
relationship of L0 < L1.
18
[0060]
The lamination gap L1 of the steel laminations 101 can be
adjusted by the shapes of the crimping portions 17 and 18 (FIG.
1). FIGS. 9(A) and 9(B) are a plan view and a cross-sectional
view schematically showing the crimping portion 5 18 which is the
V-shaped crimping portion. The crimping portion 18 is formed by
stamping the steel lamination 101. For example, the plurality of
steel laminations 101 are fixed to each other by fitting a Vshaped
convex portion 18a formed on a lower surface of one steel
10 lamination 101 into a V-shaped concave portion 18b formed on an
upper surface of the subjacent steel lamination 101. By
adjusting a protruding amount of the convex portion 18a, i.e., a
depth P (referred to as a crimping depth) of the concave portion
18b during the stamping, the lamination gap L1 of the steel
15 laminations 101 can be adjusted.
[0061]
FIGS. 10(A) and 10(B) are a plan view and a crosssectional
view schematically showing the crimping portion 17
which is the circular crimping portion. The crimping portion 17
20 is formed by stamping the steel lamination 101. For example, the
plurality of steel laminations 101 are fixed to each other by
fitting a cylindrical convex portion 17a formed on a lower
surface of one steel lamination 101 into a cylindrical concave
portion 17b formed on an upper surface of the subjacent steel
25 lamination 101. By adjusting a protruding amount of the convex
portion 17a, i.e., a depth P (referred to as a crimping depth) of
the concave portion 17b during the stamping, the lamination gap
L1 of the steel laminations 101 can be adjusted.
[0062]
30 Although FIGS. 9 and 10 show the crimping portions 17 and
18 of the steel laminations 101 of the stator core 10, the
lamination gap L0 of the steel laminations 501 of the rotor core
50 can also be adjusted in the same manner. In the first
embodiment, the crimping depth of the steel laminations 101 of
19
the stator core 10 is greater than the crimping depth of the
steel laminations 501 of the rotor core 50.
[0063]
(Action)
Next, an action of the motor 100 of the 5 first embodiment
will be described. FIG. 11 is a longitudinal-sectional view
showing a motor 100F of Comparative Example. For convenience of
description, components of the motor 100F of Comparative Example
are described using the same reference signs as the components of
10 the motor 100 of the first embodiment.
[0064]
The stator core 10 of the motor 100F of Comparative
Example is composed of steel laminations 101 each having a sheet
thickness T1 which are stacked in the axial direction with
15 lamination gaps L1. This lamination gap L1 is the same as the
lamination gap L0 of the steel laminations 501 of the rotor core
50 (L1 = L0). Other structures of the motor 100F are the same as
those of the motor 100.
[0065]
20 As in the first embodiment, the stator core 10 of the
motor 100F of Comparative Example has a first core portion 10A
and a second core portion 10B, and a first tooth portion 12A of
the first core portion 10A is narrower than a second tooth
portion 12B of the second core portion 10B (see FIG. 5). Thus,
25 when the magnetic flux from the permanent magnet 53 of the rotor
5 flows into the first tooth portion 12A, the magnetic flux
density tends to be high in the first tooth portion 12A.
[0066]
When the magnetic flux density is saturated in the first
30 tooth portion 12A, part of the magnetic flux flows in the axial
direction toward the second tooth portion 12B having a wider
width. That is, the magnetic flux flows in the direction
perpendicular to the sheet surfaces of the steel laminations 101
of the stator core 10, and thus the eddy current may be generated.
20
[0067]
FIG. 12 is a schematic diagram for explaining generation
of eddy current in the steel lamination 101. The steel
lamination 101 is thin and has a thickness T1 of, for example,
0.1 to 0.7 mm. Thus, eddy current is less likely 5 to be generated
when the magnetic flux enters the steel lamination 101 from its
end surface as indicated by the arrow F1. In contrast, eddy
current is more likely to be generated when the magnetic flux
enters the steel lamination 101 in the direction perpendicular to
10 its sheet surface as indicated by the arrow F2.
[0068]
For this reason, as in Comparative Example shown in FIG.
11, when the magnetic flux flows in the axial direction in the
stator core 10 from the first tooth portion 12A toward the second
15 tooth portion 12B, eddy current loss (iron loss) may occur, which
may lead to reduction in the motor efficiency.
[0069]
In contrast, as shown in FIG. 8, in the motor 100 of the
first embodiment, the lamination gap L1 of the steel laminations
20 101 constituting the stator core 10 is greater than the
lamination gap L0 of the steel laminations 501 constituting the
rotor core 50 (L0 < L1).
[0070]
In other words, the number of steel laminations 101 per
25 unit length (more specifically, the unit length in the axial
direction) of the stator core 10 is smaller than the number of
steel laminations 501 per unit length of the rotor core 50. Thus,
in the stator core 10, a magnetic resistance in the axial
direction is higher and the magnetic flux is less likely to flow
30 in the axial direction as compared to in the rotor core 50.
[0071]
Therefore, when the magnetic flux density is saturated in
the first tooth portion 12A, part of the magnetic flux flows in
the axial direction in a region of the rotor core 50 on the outer
21
circumferential side of the magnet insertion hole 51 and then
enters the second tooth portion 12B. Since the second tooth
portion 12B is wide, magnetic saturation is less likely to occur
in the second tooth portion 12B, and the flow of magnetic flux in
the axial direction is less 5 likely to occur.
[0072]
As a result, the magnetic flux flowing in the axial
direction in the stator core 10 can be reduced, and thus the
generation of the eddy current described with reference to FIG.
10 12 can be suppressed. That is, the eddy current loss can be
suppressed, and the motor efficiency can be enhanced.
[0073]
In the first embodiment, as described above, the magnetic
flux flows in the axial direction in the region of the rotor core
15 50 on the outer circumferential side of the magnet insertion hole
51. Since a position of the permanent magnet 53 relative to the
rotor core 50 does not change during the rotation of the rotor 5,
a change in the magnetic flux density inside the rotor core 50
during the rotation of the rotor 5 is small. Therefore, an
20 increase in the eddy current loss due to the magnetic flux
flowing in the axial direction in the region of the rotor core 50
on the outer circumferential side of the magnet insertion hole 51
is relatively small.
[0074]
25 In contrast, in the stator core 10, a positional
relationship between the tooth 12 and the permanent magnet 53
changes during the rotation of the rotor 5, and thus a change in
the magnetic flux density inside the stator core 10 during the
rotation of the rotor 5 is large. Thus, the eddy current loss is
30 more likely to increase due to the flow of the magnetic flux
flowing in the axial direction in the stator core 10. For this
reason, in the first embodiment, the stator core 10 has a
configuration in which the magnetic flux is less likely to flow
in the axial direction as compared to in the rotor core 50. This
22
configuration reduces the eddy current loss.
[0075]
FIG. 13 is a graph showing a relationship between the
motor efficiency and a difference (L1 - L0) between the
lamination gap L1 of the steel laminations 101 5 of the stator core
10 and the lamination gap L0 of the steel laminations 501 of the
rotor core 50. FIG. 13 shows a change in the motor efficiency
when the lamination gap L0 is set to 0.003 mm and the lamination
gap L1 is varied. The motor efficiency is expressed as a ratio
10 to the motor efficiency when L1 = L0 = 0.003 mm is satisfied.
[0076]
From FIG. 13, it is understood that especially high motor
efficiency (of 100.07% or more) can be obtained when the
difference L1 - L0 in the lamination gap is within a range of
15 0.004 to 0.012 mm. The reason is as follows. As the difference
L1 - L0 in the lamination gap increases, the magnetic flux is
less likely to flow in the axial direction in the stator core 10,
and thus the eddy current loss decreases. On the other hand,
when the lamination gap L1 is excessively large, iron loss of the
20 stator core 10 itself increases. Therefore, the difference L1 -
L0 in the lamination gap is desirably within the range of 0.004
to 0.012 mm.
[0077]
(Effects of Embodiment)
25 As described above, in the first embodiment, the stator
core 10 has the first core portion 10A at the end portion of the
stator core in the axial direction and the second core portion
10B at the center portion of the stator core in the axial
direction, and the area of the slot 14 is larger in the first
30 core portion 10A than in the second core portion 10B. Further,
the lamination gap L0 of the steel laminations 501 of the rotor
core 50 and the lamination gap L1 of the steel laminations 101 of
the stator core 10 satisfy L0 < L1. Thus, in the stator core 10,
the magnetic resistance in the axial direction is higher and the
23
magnetic flux is less likely to flow in the axial direction as
compared to in the rotor core 50. Consequently, the generation
of eddy current in the steel laminations 101 of the stator core
10 can be suppressed even when the magnetic saturation occurs in
the first tooth portion 12A of the first core 5 portion 10A. That
is, the eddy current loss can be reduced, and the motor
efficiency can be enhanced.
[0078]
The width in the circumferential direction of the first
10 tooth portion 12A in the first core portion 10A of the stator
core 10 is narrower than the width of the second tooth portion
12B in the circumferential direction in the second core portion
10B. Thus, the step portion 125 can be formed on the side of the
first tooth portion 12A, and the insulator 2 can be engaged with
15 the step portion 125.
[0079]
The crimping depth of the steel laminations 101 of the
stator core 10 is greater than the crimping depth of the steel
laminations 501 of the rotor core 50, and thus the above20
described relationship (L0 < L1) between the lamination gaps L0
and L1 can be achieved with a simple configuration.
[0080]
The difference L1 - L0 in the lamination gap between the
steel laminations 101 of the stator core 10 and the steel
25 laminations 501 of the rotor core 50 satisfies 0.004 mm ≤ L1 - L0
≤ 0.012 mm. Thus, the effect of reducing the eddy current loss
can be enhanced, and the motor efficiency can be further enhanced.
[0081]
Since the permanent magnet 53 is a rare earth magnet and
30 has a high residual magnetic flux density, magnetic saturation is
more likely to occur in the first tooth portion 12A. Therefore,
the effect of suppressing the eddy current loss according to the
first embodiment is exhibited more effectively.
[0082]
24
The magnet insertion hole 51 of the rotor core 50 is
formed in the V shape such that its center portion in the
circumferential direction protrudes inward in the radial
direction, and thus the magnetic flux is more likely to flow in
the axial direction in the region on the outer 5 circumferential
side of the magnet insertion hole 51. Thus, the effect of
reducing the eddy current loss in the stator core 10 can be
enhanced.
[0083]
10 The insulator 2 is engaged with the step portion 125
between the first core portion 10A and the second core portion
10B of the stator core 10, so that the protruding amount of the
insulator 2 toward the slot 14 side can be reduced. Thus, the
area of the slot 14 can be increased and the number of turns of
15 the coil 4 can be increased. As a result, a coil resistance
(i.e., copper loss) can be reduced, and the motor efficiency can
be further enhanced.
[0084]
Since the insulating film 3 is provided on the inner
20 surface of the slot 14 of the stator core 10, the coil 4 and the
stator core 10 can be insulated from each other and the area of
the slot 14 can be secured.
[0085]
Second Embodiment
25 FIG. 14 is a longitudinal-sectional view showing a motor
100A of a second embodiment. In the first embodiment described
above, the steel laminations 101 of the stator core 10 are
stacked with the equal lamination gaps L1. In contrast, in the
second embodiment, the first core portion 10A and the second core
30 portion 10B of the stator core 10 differ in the lamination gap of
the steel laminations 101.
[0086]
More specifically, the lamination gap L1 of the steel
laminations 101 of the first core portion 10A, the lamination gap
25
L2 of the steel laminations 101 of the second core portion 10B,
and the lamination gap L0 of the steel laminations 501 of the
rotor core 50 satisfy the relationship of L0 ≤ L2 < L1.
[0087]
That is, the crimping depth of the steel 5 laminations 101
of the first core portion 10A is greater than the crimping depth
of the steel laminations 101 of the second core portion 10B. The
crimping depth of the steel laminations 101 of the second core
portion 10B is greater than or equal to the crimping depth of the
10 steel laminations 501 of the rotor core 50.
[0088]
In other words, the number of steel laminations 101 per
unit length of the first core portion 10A is smaller than the
number of steel laminations 101 per unit length of the second
15 core portion 10B. In addition, the number of steel laminations
101 per unit length of the second core portion 10B is smaller
than or equal to the number of steel laminations 501 per unit
length of the rotor core 50.
[0089]
20 Thus, in the second embodiment, the magnetic resistance in
the axial direction in the first core portion 10A is higher than
the magnetic resistance in the axial direction in the second core
portion 10B. Further, the magnetic resistance in the axial
direction in the second core portion 10B is higher than or equal
25 to the magnetic resistance in the axial direction in the rotor
core 50.
[0090]
In the second embodiment, due to the above-described
relationship of L0 ≤ L2 < L1, the magnetic flux is least likely
30 to flow in the axial direction in the first core portion 10A,
while the magnetic flux is most likely to flow in the axial
direction in the region of the rotor core 50 on the outer
circumferential side of the magnet insertion hole 51. Therefore,
when the magnetic saturation occurs in the first tooth portion
26
12A, the magnetic flux flows in the axial direction in the region
of the rotor core 50 on the outer circumferential side of the
magnet insertion hole 51.
[0091]
As a result, the magnetic flux flowing 5 in the axial
direction in the stator core 10 can be reduced, and thus the
generation of the eddy current can be suppressed as in the first
embodiment. That is, the eddy current loss (iron loss) can be
suppressed, and the motor efficiency can be enhanced.
10 [0092]
The difference (L1 - L0) between the lamination gap L1 of
the steel laminations 101 of the first core portion 10A of the
stator core 10 and the lamination gap L0 of the steel laminations
501 of the rotor core 50 is desirably within the range of 0.004
15 to 0.012 mm as in the first embodiment.
[0093]
The configuration of the motor 100A of the second
embodiment is the same as that of the motor 100 of the first
embodiment (FIG. 8) except for the configuration of the stator
20 core 10.
[0094]
As described above, in the second embodiment, the
lamination gap L0 of the steel laminations 501 of the rotor core
50, the lamination gap L1 of the steel laminations 101 of the
25 first core portion 10A in the stator core 10, and the lamination
gap L2 of the steel laminations 101 of the second core portion
10B in the stator core 10 satisfy the relationship of L0 ≤ L2 <
L1. Thus, the magnetic flux is least likely to flow in the
axial direction in the first core portion 10A, and the magnetic
30 flux is most likely to flow in the axial direction in the region
of the rotor core 50 on the outer circumferential side of the
magnet insertion hole 51. Therefore, the flow of the magnetic
flux in the axial direction in the stator core 10 can be reduced,
and thus the eddy current loss can be reduced and the motor
27
efficiency can be enhanced.
[0095]
Third Embodiment
FIG. 15 is a longitudinal-sectional view showing a motor
100B of a third embodiment. In the first embodiment 5 described
above, the sheet thickness T1 of each of the steel laminations
101 of the stator core 10 and the sheet thickness T0 of each of
the steel laminations 101 of the rotor core 50 are the same. In
contrast, in the third embodiment, the stator core 10 and the
10 rotor core 50 differ in the sheet thickness of the steel
laminations 101 and 501.
[0096]
More specifically, the sheet thickness T0 of each of the
steel laminations 501 of the rotor core 50 is thicker than the
15 sheet thickness T1 of each of the steel laminations 101 of the
stator core 10. In other words, the sheet thickness T0 of each
of the steel laminations 501 of the rotor core 50 and the sheet
thickness T1 of each of the steel laminations 101 of the stator
core 10 satisfy a relationship of T0 > T1.
20 [0097]
The sheet thickness T0 of each of the steel laminations
501 of the rotor core 50 is, for example, 0.35 mm, while the
sheet thickness T1 of each of the steel laminations 101 of the
stator core 10 is, for example, 0.25 mm.
25 [0098]
The lamination gap L1 of the steel laminations 101 of the
stator core 10 and the lamination gap L0 of the steel laminations
501 of the rotor core 50 are the same (L0 = L1) in this example.
[0099]
30 As the sheet thickness of each of the steel laminations
decreases, the number of steel laminations per unit length
increases. For this reason, even when the lamination gaps L0 and
L1 of the steel laminations 101 and 501 are the same, a sum of
lamination gaps L1 of the steel laminations 101 per unit length
28
is greater than a sum of lamination gaps L0 of the steel
laminations 501 per unit length.
[0100]
Thus, in the stator core 10, the magnetic resistance in
the axial direction is higher and the magnetic 5 flux is less
likely to flow in the axial direction as compared to in the rotor
core 50. Therefore, when the magnetic flux density is saturated
in the first tooth portion 12A, the magnetic flux flows in the
axial direction in the rotor core 50.
10 [0101]
As a result, the magnetic flux flowing in the axial
direction in the stator core 10 can be reduced, and thus the
generation of the eddy current can be suppressed as in the first
embodiment. That is, the eddy current loss can be reduced, and
15 the motor efficiency can be enhanced.
[0102]
FIG. 16 is a graph showing a relationship between the
motor efficiency and a difference (T0 - T1) between the sheet
thickness T0 of the steel lamination 501 of the rotor core 50 and
20 the sheet thickness T1 of the steel lamination 101 of the stator
core 10. FIG. 16 shows a change in the motor efficiency when the
sheet thickness T0 is set to 0.35 mm and the sheet thickness T1
is varied. The motor efficiency is expressed as a ratio to the
motor efficiency when T0 = T1 = 0.35 mm is satisfied.
25 [0103]
From FIG. 16, it is understood that especially high motor
efficiency (of 100.10% or more) can be obtained when the
difference T0 - T1 in the sheet thickness is within a range of
0.05 mm to 0.15 mm. The reason is as follows. As the difference
30 T0 - T1 in the sheet thickness increases, the magnetic flux is
less likely to flow in the axial direction in the stator core 10,
and thus the eddy current loss decreases. On the other hand,
when the sheet thickness T1 is excessively thin, a hysteresis
loss of the stator core 10 increases. Therefore, the difference
29
T0 - T1 in the sheet thickness is desirably within the range of
0.05 mm to 0.15 mm.
[0104]
The configuration of the motor 100A of the third
embodiment is the same as that of the motor 5 100 of the first
embodiment (FIG. 8) except for the configuration of the stator
core 10.
[0105]
As described above, in the third embodiment, the sheet
10 thickness T0 of each of the steel laminations 501 of the rotor
core 50 and the sheet thickness T1 of each of the steel
laminations 101 of the stator core 10 satisfy the relationship of
T0 > T1. Thus, in the stator core 10, the magnetic flux is less
likely to flow in the axial direction as compared to in the rotor
15 core 50. Thus, the generation of eddy current in the steel
laminations 101 of the stator core 10 can be suppressed. That is,
the eddy current loss can be reduced, and the motor efficiency
can be enhanced.
[0106]
20 The difference T0 - T1 in the sheet thickness between the
steel lamination 501 of the rotor core 50 and the steel
lamination 101 of the stator core 10 satisfies 0.05 mm ≤ T0 - T1
≤ 0.15 mm. Thus, the effect of reducing the eddy current loss
can be enhanced, and the motor efficiency can be further enhanced.
25 [0107] The lamination gap L1 of the steel laminations 101 of the
stator core 10 and the lamination gap L0 of the steel laminations
501 of the rotor core 50 are the same (L0 = L1) in this example.
However, the lamination gaps L0 and L1 may satisfy L0 < L1 as in
the first embodiment. In this case, the difference (L1 - L0) in
30 the lamination gap is desirably within the range of 0.004 to
0.012 mm.
[0108]
Alternatively, as in the second embodiment, the lamination
gap L1 of the steel laminations 101 of the first core portion 10A,
30
the lamination gap L2 of the steel laminations 101 of the second
core portion 10B, and the lamination gap L0 of the steel
laminations 501 of the rotor core 50 may satisfy the relationship
of L0 ≤ L2 < L1.
5 [0109]
Fourth Embodiment
FIG. 17 is a longitudinal-sectional view showing a motor
100C of a fourth embodiment. In the third embodiment described
above, the sheet thickness T1 of each of the steel laminations
10 101 of the stator core 10 is constant. In contrast, in the
fourth embodiment, the first core portion 10A and the second core
portion 10B of the stator core 10 differ in the sheet thickness
of the steel laminations 101.
[0110]
15 More specifically, the sheet thickness T0 of each of the
steel laminations 501 of the rotor core 50, the sheet thickness
T1 of each of the steel laminations 101 of the first core portion
10A, and the sheet thickness T2 of each of the steel laminations
101 of the second core portion 10B satisfy the relationship of T0
20  T2 > T1.
[0111]
In other words, the number of steel laminations 101 per
unit length of the first core portion 10A is smaller than the
number of steel laminations 101 per unit length of the second
25 core portion 10B. Further, the number of steel laminations 101
per unit length of the second core portion 10B is smaller than or
equal to the number of steel laminations 501 per unit length of
the rotor core 50.
[0112]
30 Thus, in the fourth embodiment, the magnetic resistance in
the axial direction in the first core portion 10A is higher than
the magnetic resistance in the axial direction in the second core
portion 10B. Further, the magnetic resistance in the axial
direction in the second core portion 10B is higher than or equal
31
to the magnetic resistance in the axial direction in the rotor
core 50.
[0113]
In the fourth embodiment, due to the above-described
relationship of T0  T2 > T1, the magnetic flux 5 is least likely
to flow in the axial direction in the first core portion 10A, and
the magnetic flux is most likely to flow in the axial direction
in the region of the rotor core 50 on the outer circumferential
side of the magnet insertion hole 51. Therefore, when the
10 magnetic saturation occurs in the first tooth portion 12A, the
magnetic flux flows in the axial direction in the region of the
rotor core 50 on the outer circumferential side of the magnet
insertion hole 51.
[0114]
15 As a result, the magnetic flux flowing in the axial
direction in the stator core 10 can be reduced, and thus the
generation of the eddy current is suppressed as in the first
embodiment. That is, the eddy current loss can be reduced, and
the motor efficiency can be enhanced.
20 [0115]
The configuration of the motor 100A of the fourth
embodiment is the same as that of the motor 100 of the first
embodiment (FIG. 8) except for the configuration of the stator
core 10.
25 [0116]
As described above, in the fourth embodiment, the sheet
thickness T0 of each of the steel laminations 501 of the rotor
core 50, the sheet thickness T1 of each of the steel laminations
101 of the first core portion 10A in the stator core 10, and the
30 sheet thickness T2 of each of the steel laminations 101 of the
second core portion 10B satisfy the relationship of T0  T2 > T1.
Thus, the magnetic flux is least likely to flow in the axial
direction in the first core portion 10A, and the magnetic flux is
most likely to flow in the axial direction in the region of the
32
rotor core 50 on the outer circumferential side of the magnet
insertion hole 51. Therefore, the flow of the magnetic flux in
the axial direction in the stator core 10 can be reduced, and
thus the eddy current loss can be reduced and the motor
efficiency 5 can be enhanced.
[0117]
The lamination gap L1 of the steel laminations 101 of the
stator core 10 and the lamination gap L0 of the steel laminations
501 of the rotor core 50 are the same (L0 = L1) in this example.
10 However, the lamination gaps L0 and L1 may satisfy L0 < L1 as in
the first embodiment. In this case, the difference (L1 - L0) in
the lamination gap is desirably within the range of 0.004 to
0.012 mm.
[0118]
15 Alternatively, as in the second embodiment, the lamination
gap L1 of the steel laminations 101 of the first core portion 10A,
the lamination gap L2 of the steel laminations 101 of the second
core portion 10B, and the lamination gap L0 of the steel
laminations 501 of the rotor core 50 may satisfy the relationship
20 of L0 ≤ L2 < L1.
[0119]
Fifth Embodiment
FIG. 18 is a longitudinal-sectional view showing a motor
100D of a fifth embodiment. In the above-described first to
25 fourth embodiments, the length of the rotor core 50 in the axial
direction and the length of the stator core 10 in the axial
direction are the same. In contrast, in the fifth embodiment,
the length Hr of the rotor core 50 in the axial direction is
longer than the length Hs of the stator core 10 in the axial
30 direction.
[0120]
As shown in FIG. 18, both ends of the rotor core 50 in the
axial direction protrude from the stator core 10 in the axial
direction. The length Hr of the rotor core 50 in the axial
33
direction is, for example, 50 mm, while the length Hs of the
stator core 10 in the axial direction is, for example, 45 mm.
[0121]
Other structures of this embodiment are as described in
the fourth embodiment. That is, the sheet thickness 5 T0 of each
of the steel laminations 501 of the rotor core 50, the sheet
thickness T1 of each of the steel laminations 101 of the first
core portion 10A, and the sheet thickness T2 of each of the steel
laminations 101 of the second core portion 10B satisfy the
10 relationship of T0  T2 > T1.
[0122]
In the fifth embodiment, the length Hr of the rotor core
50 in the axial direction is longer than the length Hs of the
stator core 10 in the axial direction. Thus, the magnetic flux
15 of the permanent magnet 53 interlinking with the coil 4 can be
increased without increasing the wire length of the coil 4. That
is, the coil resistance can be reduced, and the motor efficiency
can be further enhanced.
[0123]
20 Since the length Hr of the rotor core 50 in the axial
direction is longer than the length Hs of the stator core 10 in
the axial direction, the magnetic flux density at both end
portions (i.e., at the first core portions 10A) of the stator
core 10 in the axial direction increases. This results in an
25 increase in the magnetic flux flowing from the rotor core 50 to
the first tooth portion 12A. Thus, the magnetic saturation in
the first tooth portion 12A tends to cause the flow of magnetic
flux in the axial direction, and the eddy current loss described
above is especially likely to occur.
30 [0124]
In the fifth embodiment, the occurrence of eddy current
loss in the stator core 10 is suppressed due to the relationship
of T0  T2 > T1 described above. This effect of suppressing the
eddy current loss is especially effectively exhibited in the
34
motor 10D in which the length Hr of the rotor core 50 in the
axial direction is longer than the length Hs of the stator core
10 in the axial direction.
[0125]
As described above, in the fifth embodiment, 5 the length Hr
of the rotor core 50 in the axial direction is longer than the
length Hs of the stator core 10 in the axial direction. Thus,
the effect of reducing the eddy current loss (i.e., the effect of
enhancing the motor efficiency) due to the relationship of T0 
10 T2 > T1 described above can be especially effectively exhibited.
[0126]
In the fifth embodiment, a configuration in which the
length Hr of the rotor core 50 in the axial direction is longer
than the length Hs of the stator core 10 in the axial direction
15 is employed in the motor described in the fourth embodiment
described above. However, the configuration in which the length
Hr of the rotor core 50 in the axial direction is longer than the
length Hs of the stator core 10 in the axial direction may be
employed in any of the motors described in the first to third
20 embodiments.
[0127]
FIG. 19 is a longitudinal-sectional view showing a motor
100E in which the configuration in which the length Hr of the
rotor core 50 in the axial direction is longer than the length Hs
25 of the stator core 10 in the axial direction is employed in the
motor 100 (FIG. 8) described in the first embodiment. As shown
in FIG. 19, both ends of the rotor core 50 in the axial direction
protrude from the stator core 10 in the axial direction.
[0128]
30 The stator core 10 and the rotor core 50 are configured in
a similar manner to the first embodiment except that the stator
core 10 and the rotor core 50 have different lengths in the axial
direction. That is, the lamination gap L1 of the steel
laminations 101 of the stator core 10 is wider than the
35
lamination gap L0 of the steel laminations 501 of the rotor core
50 (L0 < L1).
[0129]
The occurrence of eddy current loss in the stator core 10
can be suppressed due to the relationship of 5 L0 < L1 described
above. The effect of suppressing the eddy current loss is
especially effectively exhibited in the motor 10E in which the
length Hr of the rotor core 50 in the axial direction is longer
than the length Hs of the stator core 10 in the axial direction.
10 [0130]
Also, when the configuration in which the length Hr of the
rotor core 50 in the axial direction is longer than the length Hs
of the stator core 10 in the axial direction is employed in the
motors described in the second and third embodiments, the effect
15 of suppressing the eddy current loss can be especially
efficiently exhibited.
[0131]
(Rotary Compressor)
Next, the rotary compressor 300 to which the motor of each
20 embodiment described above is applicable will be described. FIG.
20 is a cross-sectional view showing the rotary compressor 300.
The rotary compressor 300 includes a frame 301, a compression
mechanism 310 disposed in the frame 301, and the motor 100 that
drives the compression mechanism 310.
25 [0132]
The compression mechanism 310 includes a cylinder 311
having a cylinder chamber 312, a rolling piston 314 fixed to the
shaft 58 of the motor 100, a vane (not shown) dividing the inside
of the cylinder chamber 312 into a suction side and a compression
30 side, and an upper frame 316 and a lower frame 317 which close
end surfaces of the cylinder chamber 312 in the axial direction
and into which the shaft 58 is inserted. An upper discharge
muffler 318 and a lower discharge muffler 319 are mounted on the
upper frame 316 and the lower frame 317, respectively.
36
[0133]
The frame 301 is a cylindrical container that is formed by
drawing a steel sheet having a thickness of, for example, 3 mm.
Refrigerating machine oil (not shown) for lubricating sliding
portions of the compression mechanism 310 is stored 5 at the bottom
of the frame 301. The shaft 58 is rotatably held by the upper
frame 316 and the lower frame 317.
[0134]
The cylinder 311 has the cylinder chamber 312 therein. The
10 rolling piston 314 eccentrically rotates in the cylinder chamber
312. The shaft 58 has an eccentric shaft portion to which a
rolling piston 314 is fitted.
[0135]
The stator core 10 of the motor 100 is fitted to the
15 inside of the frame 301 by shrink-fitting. The coil 4 wound on
the stator core 10 is supplied with power from a glass terminal
305 fixed to the frame 301. The shaft 58 is fixed to a shaft
hole 55 (FIG. 1) of the rotor 5.
[0136]
20 An accumulator 302 that stores refrigerant gas is attached
to an outer side of the frame 301. A suction pipe 303 is fixed
to the frame 301, and the refrigerant gas is supplied from the
accumulator 302 to the cylinder 311 via the suction pipe 303. A
discharge pipe 307 through which the refrigerant is discharged to
25 the outside is provided at an upper portion of the frame 301.
[0137]
For example, R410A, R407C, R22 or the like can be used as
the refrigerant. From the viewpoint of preventing global warming,
a low GWP (global warming potential) refrigerant is desirably
30 used. For example, the following refrigerant can be used as the
low GWP refrigerant.
[0138]
(1) First, a halogenated hydrocarbon having a carbon
double bond in its composition, for example, HFO (Hydro-Fluoro37
Orefin)-1234yf (CF3CF=CH2), can be used. The GWP of HFO-1234yf is
4.
(2) Further, a hydrocarbon having a carbon double bond in
its composition, for example, R1270 (propylene), may be used.
The GWP of R1270 is 3, which is lower than that 5 of HFO-1234yf,
but the flammability of R1270 is higher than that of HFO-1234yf.
(3) A mixture containing at least one of a halogenated
hydrocarbon having a carbon double bond in its composition and a
hydrocarbon having a carbon double bond in its composition, for
10 example, a mixture of HFO-1234yf and R32, may also be used. HFO-
1234yf described above is a low-pressure refrigerant and thereby
tends to increase a pressure loss which may lead to reduction in
the performance of a refrigeration cycle (particularly,
evaporator). For this reason, a mixture of the HFO-1234yf with
15 R32 or R41, which is higher pressure refrigerant than HFO-1234yf,
is desirable in practice.
[0139]
An operation of the rotary compressor 300 is as follows.
Refrigerant gas supplied from the accumulator 302 is supplied to
20 the cylinder chamber 312 of the cylinder 311 through the suction
pipe 303. When the motor 100 is driven to rotate the rotor 5,
the shaft 58 rotates together with the rotor 5. Then, the
rolling piston 314 fitted to the shaft 58 eccentrically rotates
in the cylinder chamber 312, thereby compressing the refrigerant
25 in the cylinder chamber 312. The compressed refrigerant passes
through the discharge mufflers 318 and 319, flows upward in the
frame 301 through holes (not shown) provided in the motor 100,
and is then discharged to the outside through the discharge pipe
307.
30 [0140]
The motor described above in each embodiment has high
motor efficiency by suppressing eddy current. Thus, by using the
motor described in each embodiment as a drive source of the
compressor 300, the operation efficiency of the compressor 300
38
can be enhanced.
[0141]
(Air Conditioner)
Next, an air conditioner 400 including the compressor 300
shown in FIG. 20 will be described. FIG. 21 is 5 a diagram showing
the air conditioner 400. The air conditioner 400 shown in FIG.
21 includes a compressor 401, a condenser 402, a throttle device
(a decompression device) 403, and an evaporator 404. The
compressor 401, the condenser 402, the throttle device 403, and
10 the evaporator 404 are connected by a refrigerant pipe 407 to
constitute a refrigeration cycle. That is, the refrigerant
circulates through the compressor 401, the condenser 402, the
throttle device 403, and the evaporator 404 in this order.
[0142]
15 The compressor 401, the condenser 402, and the throttle
device 403 are provided in an outdoor unit 410. The compressor
401 is constituted by the rotary compressor 300 shown in FIG. 20.
The outdoor unit 410 is provided with an outdoor fan 405 that
supplies outdoor air to the condenser 402. The evaporator 404 is
20 provided in an indoor unit 420. The indoor unit 420 is provided
with an indoor fan 406 that supplies indoor air to the evaporator
404.
[0143]
An operation of the air conditioner 400 is as follows. The
25 compressor 401 compresses sucked refrigerant and sends out the
compressed refrigerant. The condenser 402 exchanges heat between
the refrigerant flowing in from the compressor 401 and the
outdoor air to condense and liquefy the refrigerant, and sends
out the liquefied refrigerant to the refrigerant pipe 407. The
30 outdoor fan 405 supplies the outdoor air to the condenser 402.
The throttle device 403 adjusts the pressure or the like of the
refrigerant flowing through the refrigerant pipe 407 by changing
its opening degree.
[0144]
39
The evaporator 404 exchanges heat between the refrigerant
brought into a low-pressure state by the throttle device 403 and
the indoor air to cause the refrigerant to take heat from the air
and evaporate (vaporize), and then sends out the evaporated
refrigerant to the refrigerant pipe 407. The 5 indoor fan 406
supplies the indoor air to the evaporator 404. Thus, cooled air
from which the heat is taken in the evaporator 404 is supplied to
the room.
[0145]
10 The air conditioner 400 has the compressor 401 whose
operation efficiency is enhanced by employing the motor described
in each embodiment. Thus, the operation efficiency of the air
conditioner 400 can be enhanced.
[0146]
15 Although the desirable embodiments of the present
invention have been specifically described above, the present
invention is not limited to the above-described embodiments, and
various modifications or changes can be made to those embodiments
without departing from the scope of the present invention.
20 DESCRIPTION OF REFERENCE CHARACTERS
[0147]
1 stator; 2 insulator; 3 insulating film; 4 coil; 5
rotor; 9, 9A, 9B split core; 10 stator core; 10A first core
portion; 10B second core portion; 11 yoke; 11A first yoke; 11B
25 second yoke; 12 tooth; 12A first tooth; 12B second tooth; 13
tooth end portion; 13A first tooth end portion; 13B second
tooth end portion; 14 slot; 16 hole; 17, 18 crimping portion;
20 body portion; 21 flange portion; 25 wall portion; 26
protrusion; 50 rotor core; 51 magnet insertion hole; 52 flux
30 barrier; 53 permanent magnet; 55 shaft hole; 58 shaft; 100,
100A, 100B, 100C, 100D, 100E motor; 101 steel lamination; 111A,
111B inner circumferential surface; 121A, 121B side surface;
125 step; 131A, 131B outer circumferential surface; 300 rotary
compressor (compressor); 301 frame; 310 compression mechanism;
40
400 air conditioner; 401 compressor; 402 condenser; 403
throttle device; 404 evaporator; 405 outdoor fan; 406 indoor
fan; 407 refrigerant pipe; 410 outdoor unit; 420 indoor unit;
501 steel lamination.
5
41
We Claim :
1. A motor comprising:
a rotor rotatable about a rotation axis, the rotor having
a rotor core having steel laminations stacked in an axial
direction of the rotation axis and a permanent 5 magnet embedded in
the rotor core; and
a stator provided so as to surround the rotor, the stator
having a stator core having steel laminations stacked in the
axial direction and a coil wound on the stator core,
10 wherein the stator core has a slot in which the coil is
housed,
wherein the stator core has a first core portion at an end
portion of the stator core in the axial direction and a second
core portion at a center portion of the stator core in the axial
15 direction, an area of the slot being larger in the first core
portion than in the second core portion, and
wherein a sheet thickness T0 and a lamination gap L0 of
the steel laminations of the rotor core and a sheet thickness T1
and a lamination gap L1 of the steel laminations of the first
20 core portion of the stator core satisfy at least one of:
T0 > T1 and L0 < L1.
2. The motor according to claim 1, wherein the stator core
has a yoke extending in a circumferential direction about the
25 rotation axis and a tooth extending from the yoke toward the
rotation axis, and
wherein a width of the tooth in the first core portion of
the stator core in the circumferential direction is narrower than
a width of the tooth in the second core portion of the stator
30 core in the circumferential direction.
3. The motor according to claim 1 or 2, wherein a crimping
depth of the steel laminations of the first core portion of the
stator core is greater than a crimping depth of the steel
42
laminations of the rotor core.
4. The motor according to any one of claims 1 to 3, wherein
the lamination gap L0 of the steel laminations of the rotor core,
the lamination gap L1 of the steel laminations 5 of the first core
portion of the stator core, and a lamination gap L2 of steel
laminations of the second core portion of the stator core
satisfy:
L0 ≤ L2 < L1.
10
5. The motor according to any one of claims 1 to 4, wherein a
difference L1 - L0 between the lamination gap L1 and the
lamination gap L0 satisfies:
0.004 mm ≤ L1 - L0 ≤ 0.012 mm.
15
6. The motor according to any one of claims 1 to 5, wherein
the sheet thickness T0 of the steel laminations of the rotor core,
the sheet thickness T1 of the steel laminations of the first core
portion of the stator core, and a sheet thickness T2 of the steel
20 laminations of the second core portion of the stator core
satisfy:
T0  T2 > T1.
7. The motor according to any one of claims 1 to 6, wherein a
25 difference T0 - T1 between the sheet thickness T0 and the sheet
thickness T1 satisfies:
0.05 mm ≤ T0 - T1 ≤ 0.15 mm.
8. The motor according to any one of claims 1 to 7, wherein a
30 length of the rotor core in the axial direction is longer than a
length of the stator core in the axial direction.
9. The motor according to any one of claims 1 to 8, wherein
the permanent magnet is a rare earth magnet.
43
10. The motor according to any one of claims 1 to 9, wherein
the rotor core has a magnet insertion hole into which the
permanent magnet is inserted, and
wherein the magnet insertion hole is formed in a V shape
such that a center portion of the magnetic insertion 5 hole in a
circumferential direction about the rotation axis protrudes
toward the rotation axis.
11. The motor according to any one of claims 1 to 10, further
10 comprising an insulator disposed between the stator core and the
coil,
wherein the insulator is engaged with a step portion
formed between the first core portion and the second core portion
of the stator core.
15
12. The motor according to claim 11, wherein the insulator is
disposed in the first core portion of the stator core, and
wherein an insulating film is disposed on an inner surface
of the slot of the stator core.
20
13. A compressor comprising:
the motor according to any one of claims 1 to 12, and
a compression mechanism driven by the motor.
25
14. An air conditioner
decompression device and an evaporator,
the compressor comprising:
the motor according to any one of claims 1 to 12
a compression mechanism driven 5 by the motor.