FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
ROTOR, MOTOR, COMPRESSOR, AND REFRIGERATION AND AIR-CONDITIONING
DEVICE
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI
2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED
2
DESCRIPTION
TECHNICAL FIELD
[0001]
The present invention relates to a rotor for use in a 5 motor.
BACKGROUND ART
[0002]
Rotors having magnet insertion holes provided with flux
barriers, which are spaces, have been used. In such a rotor, 10 leakage flux can be reduced, and thus motor efficiency can be
enhanced. However, because of the presence of a thin-wall
portion between the outer peripheral surface of the rotor and
the flux barrier, stress tends to be concentrated on the thinwall
portion during rotation of the rotor. As the rotation 15 speed of the rotor increases, this stress increases, and as a
result, the rotor, especially the thin-wall portion, is easily
deformed. In view of this, a rotor having a center rib (also
simply referred to as a “rib”) between two magnet insertion
holes is proposed (see, for example, Patent Reference 1). In 20 the rotor having the center rib, a part of stress occurring in
the rotor is dispersed to the center rib, and thus stress
generated in the thin-wall portion is reduced. This can
prevent deformation of the rotor.
PRIOR ART REFERENCE 25 PATENT REFERENCE
[0003]
Patent Reference 1: Japanese Patent Application
Publication No. 2017-192211
SUMMARY OF THE INVENTION 30 PROBLEM TO BE SOLVED BY THE INVENTION
[0004]
In the case where the center rib is present between two
magnet insertion holes, however, the strength of the rotor to a
3
centrifugal force increases, but magnetic flux passing through
the center rib, that is, leakage flux, increases, and motor
efficiency decreases, disadvantageously.
[0005]
It is therefore an object of the present invention to 5 increase strength of a rotor to a centrifugal force while
reducing leakage flux in the rotor.
MEANS OF SOLVING THE PROBLEM
[0006]
A rotor according to an aspect of the present invention 10 includes: an electromagnetic steel sheet including a first
magnet insertion hole, a second magnet insertion hole, and a
center rib between the first magnet insertion hole and the
second magnet insertion hole; a first permanent magnet disposed
in the first magnet insertion hole; and a second permanent 15 magnet disposed in the second magnet insertion hole. The first
magnet insertion hole and the second magnet insertion hole are
arranged in a V shape in a plane orthogonal to an axial
direction. The rotor satisfies T ≤ W1 ≤ 2 × T ≤ W2, where T is
a thickness of the electromagnetic steel sheet, W1 is a minimum 20 width of the center rib in a direction orthogonal to a radial
direction, and W2 is a maximum width of the center rib in the
direction orthogonal to the radial direction.
EFFECTS OF THE INVENTION
[0007] 25 The present invention can increase strength of the rotor
to a centrifugal force while reducing leakage flux in the rotor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008]
FIG. 1 is a cross-sectional view schematically 30 illustrating a structure of a motor according to a first
embodiment of the present invention.
FIG. 2 is a diagram illustrating another example of a
stator.
4
FIG. 3 is a plan view schematically illustrating a
structure of a rotor core.
FIG. 4 is an enlarged view illustrating a region
constituting one magnetic pole of a rotor.
FIG. 5 is an enlarged view schematically illustrating a 5 structure of a center rib.
FIG. 6 is a graph showing a relationship between stress
generated in the rotor core and a minimum width of the center
rib.
FIG. 7 is a cross-sectional view schematically 10 illustrating a structure of a rotor according to a comparative
example.
FIG. 8 is an enlarged view illustrating a structure of a
thin-wall portion between the outer peripheral surface of an
electromagnetic steel sheet and a first magnet insertion hole. 15 FIG. 9 is an enlarged view illustrating a structure of a
thin-wall portion between the outer peripheral surface of the
electromagnetic steel sheet and a second magnet insertion hole.
FIG. 10 is a graph showing a relationship between stress
generated in a rotor core and a minimum width of the thin-wall 20 portion.
FIG. 11 is a diagram illustrating another example of the
rotor core.
FIG. 12 is a cross-sectional view schematically
illustrating a structure of a compressor according to a second 25 embodiment of the present invention.
FIG. 13 is a diagram illustrating a configuration of an
air conditioner according to a third embodiment of the present
invention.
MODE FOR CARRYING OUT THE INVENTION 30 [0009]
FIRST EMBODIMENT
In xyz orthogonal coordinate systems illustrated in the
drawings, a z-axis direction (z axis) represents a direction
5
parallel to an axis line Ax of a rotor 2, an x-axis direction
(x axis) represents a direction orthogonal to the z-axis
direction (z axis), and a y-axis direction (y axis) is a
direction orthogonal to both the z-axis direction and the xaxis
direction. The axis line Ax is a rotation center of the 5 rotor 2. The axis line Ax also represents an axis line of a
motor 1 described later. A direction parallel to the axis line
Ax will be referred to as an “axial direction of the rotor 2”
or simply as an “axial direction.” The “radial direction”
refers to a radial direction of the rotor 2 or a stator 3, and 10 is a direction orthogonal to the axis line Ax. An xy plane is
a plane orthogonal to the axial direction. Arrow D1 represents
a circumferential direction about the axis line Ax.
[0010]
FIG. 1 is a cross-sectional view schematically 15 illustrating a structure of the motor 1 according to a first
embodiment of the present invention.
The motor 1 includes the rotor 2 and the stator 3.
[0011]
In this embodiment, the motor 1 is, for example, a three- 20 phase synchronous motor. Specifically, the motor 1 is a
permanent magnet synchronous motor (also called a brushless DC
motor) such as an interior permanent magnet motor.
[0012]
The rotor 2 is rotatably disposed inside the stator 3. 25 An air gap is formed between the rotor 2 and the stator 3. The
rotor 2 rotates about the axis line Ax. The rotor 2 includes a
rotor core 21, at least one permanent magnet 22, and a shaft 24.
[0013]
The stator 3 is disposed outside the rotor 2. The stator 30 3 includes, for example, an annular stator core, and a stator
winding wound around the stator core. In the example
illustrated in FIG. 1, the stator 3 includes a yoke 35
extending in the circumferential direction of the stator 3, and
6
a plurality of teeth 34 extending in the radial directions from
the yoke 35. Spaces between the teeth 34 serve as slots 33 in
each of which the stator winding is disposed.
[0014]
The stator winding used for the stator 3 is, for example, 5 a winding in which an insulation film is formed around a
conductor such as copper or aluminum.
[0015]
The stator core of the stator 3 is constituted by, for
example, annular electromagnetic steel sheets stacked in the 10 axial direction. Each of the electromagnetic steel sheets is
punched in a predetermined shape beforehand. Each
electromagnetic steel sheet has a thickness of, for example,
0.25 mm to 0.5 mm. The electromagnetic steel sheets are fixed
together by swaging. 15 [0016]
FIG. 2 is a diagram illustrating another example of the
stator 3.
The stator 3 illustrated in FIG. 2 includes, in addition
to the yoke 35 and the plurality of teeth 34, at least one hole 20 36 extending in the axial direction and at least one notch 37
formed in the outer peripheral surface of the stator 3.
Instead of the stator 3 illustrated in FIG. 1, the stator 3
illustrated in FIG. 2 may be used for the motor 1.
[0017] 25 In the example illustrated in FIG. 2, a plurality of
holes 36 are formed in the yoke 35. Each of the holes 36
extends in the axial direction. In a case where the motor 1 is
used as a driving source of a compressor, for example, each
hole 36 is used as a channel through which a refrigerant flows 30 in the compressor. Accordingly, the motor 1 can be effectively
cooled in the compressor.
[0018]
In the example illustrated in FIG. 2, a plurality of
7
notches 37 are formed on the outer peripheral surface of the
stator 3. Accordingly, in the xy plane, the stator 3 has a
maximum radius Ra and a radius Rb smaller than the maximum
radius Ra. The radius Rb is a minimum radius from the axis
line Ax to the notches 37. In the case where the motor 1 is 5 used as a driving source of the compressor, for example, a
space is formed between a housing of the compressor and the
notches 37, and this space is used as a channel through which a
refrigerant passes. Accordingly, the motor 1 can be
effectively cooled in the compressor. 10 [0019]
The structure of the rotor 2 will be described
specifically.
In the example illustrated in FIG. 1, the rotor 2
includes a rotor core 21, a plurality of permanent magnets 22 15 embedded in the rotor core 21, and a shaft 24 fitted in a
center portion 23 of the rotor core 21. The rotor 2 includes
two or more magnetic poles. Two or more permanent magnets 22
constitute one magnetic pole of the rotor 2.
[0020] 20 FIG. 3 is a plan view schematically illustrating a
structure of the rotor core 21.
FIG. 4 is an enlarged view illustrating a region
constituting one magnetic pole of the rotor 2.
The rotor core 21 is an annular rotor core. The rotor 25 core 21 includes at least one electromagnetic steel sheet 20.
In this embodiment, a plurality of electromagnetic steel sheets
20 are stacked in the axial direction. Each of the
electromagnetic steel sheets 20 includes two or more pairs of
magnet insertion holes 210, at least one center rib 213, at 30 least one thin-wall portion 214, and the center portion 23
(also referred to as a magnet insertion hole).
[0021]
Each pair of the magnet insertion holes 210 includes a
8
first magnet insertion hole 211 and a second magnet insertion
hole 212. In the xy plane, the center of one pair of magnet
insertion holes 210 projects toward the center (i.e., the axis
line Ax) of the rotor core 21. That is, one pair of magnet
insertion holes 210 (i.e., the first magnet insertion hole 211 5 and the second magnet insertion hole 212) is arranged in a V
shape in the xy plane. The center rib 213 is formed between
the first magnet insertion hole 211 and the second magnet
insertion hole 212.
[0022] 10 The first magnet insertion hole 211 includes a magnet
placement portion 211a (also referred to as a first magnet
placement portion) where the permanent magnet 22 serving as a
first permanent magnet is placed and a flux barrier 211b (also
referred to as a first flux barrier) that is a space between 15 the permanent magnet 22 and the thin-wall portion 214.
[0023]
The second magnet insertion hole 212 includes a magnet
placement portion 212a (also referred to as a second magnet
placement portion) where the permanent magnet 22 serving as a 20 second permanent magnet is placed and a flux barrier 212b (also
referred to as a second flux barrier) that is a space between
the permanent magnet 22 and the thin-wall portion 214.
[0024]
The thin-wall portion 214 between the outer peripheral 25 surface of the electromagnetic steel sheet 20 and the first
magnet insertion hole 211 will be also referred to as a “first
thin-wall portion.” The thin-wall portion 214 between the
outer peripheral surface of the electromagnetic steel sheet 20
and the second magnet insertion hole 212 will be also referred 30 to as a “second thin-wall portion.”
[0025]
In the example illustrated in FIG. 3, each
electromagnetic steel sheet 20 includes the center portion 23,
9
six magnet insertion holes 210, six center ribs 213, and twelve
thin-wall portions 214. The six magnet insertion holes 210 are
arranged in the circumferential direction of the rotor 2. Each
first magnet insertion hole 211 and each second magnet
insertion hole 212 extend in the axial direction. The center 5 portion 23 is a hole extending in the axial direction.
[0026]
The permanent magnet 22 as the first permanent magnet is
placed in each first magnet insertion hole 211. The permanent
magnet 22 as the second permanent magnet is placed in each 10 second magnet insertion hole 212.
[0027]
Each permanent magnet 22 is, for example, a plate
permanent magnet. Each permanent magnet 22 is, for example, a
rare earth magnet containing neodymium (Nd) and dysprosium (Dy). 15 The rare earth magnet has a high residual flux density and a
high coercive force. Thus, in the case of using rare earth
magnets as the permanent magnets 22, the motor 1 having
enhanced efficiency and enhanced demagnetization resistance can
be obtained. As the permanent magnets 22, magnets except for 20 rare earth magnets, such as ferrite sintered magnets, may be
used.
[0028]
One pair of magnet insertion holes 210 is associated with
one magnetic pole of the rotor 2. Specifically, two permanent 25 magnets 22 (i.e., the first permanent magnet and the second
permanent magnet) placed in one pair of magnet insertion holes
210 constitute one magnetic pole of the rotor 2. Thus, in this
embodiment, the rotor 2 has six magnetic poles.
[0029] 30 In general, since a centrifugal force is exerted on a
rotor core during rotation of the rotor, if no center rib is
formed on the rotor core, large stress is applied to thin-wall
portions between the outer peripheral surface of the rotor core
10
and magnet insertion holes (specifically flux barriers). If
this stress is large, the rotor core (especially the thin-wall
portions) is easily deformed. On the other hand, in this
embodiment, since the center ribs 213 are formed in the rotor
core 21, part of the stress generated in the rotor 2 is 5 dispersed to the center ribs 213, and thus stress applied to
the thin-wall portions 214 is reduced. Accordingly,
deformation of the rotor core 21, especially the thin-wall
portions 214, can be prevented.
[0030] 10 FIG. 5 is an enlarged view schematically illustrating a
structure of the center rib 213.
In general, degradation of magnetic properties (i.e.,
decrease in relative permeability) occurs in the range of a
thickness T of one electromagnetic steel sheet from the surface 15 of the electromagnetic steel sheet formed by punching. In the
example illustrated in FIG. 5, degradation of magnetic
properties occurs in a hatched portion of the center rib 213.
Accordingly, magnetic flux from the permanent magnets 22 does
not easily pass through portions where degradation of magnetic 20 properties occurs. That is, leakage flux in the center rib 213
can be reduced.
[0031]
On the other hand, strength decreases in portions where
degradation of magnetic properties occurs. In view of this, 25 the rotor 2 preferably satisfies 2 × T ≤ W2, where W2 is a
maximum width of the center rib 213 in a direction orthogonal
to the radial direction of the rotor 2. Accordingly, strength
does not decrease in a region 213a of the center rib 213. As a
result, strength of the rotor 2 (especially the rotor core 21) 30 can be increased. In the example illustrated in FIG. 5, the
direction orthogonal to the radial direction of the rotor 2 is
the x-axis direction. In FIG. 5, the region 213a is an
unhatched region. A width T in FIG. 5 corresponds to the
11
thickness T of each electromagnetic steel sheet. In this
embodiment, the maximum width W2 is a width of an inner end
portion of the center rib 213 in the radial direction.
[0032]
The rotor 2 preferably satisfies T ≤ W1 where W1 is a 5 minimum width of the center rib 213 in the direction orthogonal
to the radial direction of the rotor 2. Accordingly, the first
magnet insertion hole 211, the second magnet insertion hole 212,
and the center rib 213 can be easily formed by punching. In
this embodiment, the minimum width W1 is a width of an outer 10 end portion of the center rib 213 in the radial direction.
[0033]
In addition, the rotor 2 preferably satisfies W1 ≤ 2 × T.
Accordingly, in the case of forming the center rib 213 by
punching, magnetic properties in part of the region of the 15 center rib 213 can be degraded. In the example illustrated in
FIG. 5, magnetic properties can be degraded in an upper region
of the center rib 213, that is, a hatched region. Consequently,
leakage flux in the center ribs 213 can be reduced.
[0034] 20 Thus, the minimum width W1 of the center rib 213
preferably satisfies T ≤ W1 ≤ 2 × T. Accordingly, the
advantages described above can be obtained.
[0035]
FIG. 6 is a graph showing a relationship between stress 25 generated in the rotor core 21 and the minimum width W1 of the
center rib 213. In FIG. 6, the first vertical axis represents
a maximum stress generated in the rotor core 21 (specifically a
ratio with respect to a comparative example), and the second
vertical axis represents a maximum magnetic force of the rotor 30 2 (specifically a ratio with respect to the comparative
example), and the horizontal axis represents W1/T.
In FIG. 6, the broken line F1 represents a maximum stress
generated in the rotor core 21 with respect to a change in the
12
minimum width W1 in a case where a maximum stress generated in
a rotor core 21a of a rotor 2a according to a comparative
example is 100%. In FIG. 6, the solid line F2 represents a
maximum magnetic force of the rotor 2 with respect to a change
in the minimum width W1 in a case where the magnetic force of 5 the rotor 2a of the comparative example is 100%.
[0036]
FIG. 7 is a cross-sectional view schematically
illustrating a structure of the rotor 2a of the comparative
example. In the rotor 2a of the comparative example, no center 10 rib 213 is formed on the rotor core 21a. In addition, in the
rotor 2a of the comparative example, one magnet insertion hole
210a is associated with one magnetic pole, and one plate
permanent magnet 22a is placed in each magnet insertion hole
210a. 15 [0037]
In this embodiment, as illustrated in FIG. 6, a ratio
W1/T of the minimum width W1 with respect to the thickness T of
the electromagnetic steel sheet 20 preferably satisfies 0.9 ≤
W1/T ≤ 1.9. Accordingly, stress applied to the rotor core 21, 20 especially the center rib 213 and the thin-wall portion 214,
can be reduced. In addition, since leakage flux in the center
rib 213 can be reduced, a magnetic force of the rotor 2 can be
enhanced. In this embodiment, the rotor 2 satisfies W1 < W2
and 0.9 ≤ W1/T ≤ 1.9, and thus, the advantages described above 25 can be obtained.
[0038]
In particular, since the rotor 2 satisfies W1 < W2 and
0.9 ≤ W1/T ≤ 1.5, stress applied to the rotor core 21,
especially the center rib 213 and the thin-wall portion 214 can 30 be reduced, and a magnetic force of the rotor 2 can be
increased.
[0039]
FIG. 8 is an enlarged view illustrating a structure of
13
the thin-wall portion 214 between the outer peripheral surface
of the electromagnetic steel sheet 20 and the first magnet
insertion hole 211.
FIG. 9 is an enlarged view illustrating a structure of
the thin-wall portion 214 between the outer peripheral surface 5 of the electromagnetic steel sheet 20 and the second magnet
insertion hole 212.
As illustrated in FIG. 8, in the xy plane, a minimum
width in the radial direction (also referred to as a first
radial direction) of the thin-wall portion 214 as the first 10 thin-wall portion is represented as W3.
As illustrated in FIG. 9, in the xy plane, a minimum
width in the radial direction (also referred to as a second
radial direction) of the thin-wall portion 214 as the second
thin-wall portion is represented as W4. In this embodiment, 15 the minimum width W3 is equal to the minimum width W4. In this
embodiment, the thin-wall portions 214 have the same shape and
the same minimum width. Alternatively, the thin-wall portions
214 may have different shapes.
[0040] 20 FIG. 10 is a graph showing a relationship between stress
generated in the rotor core 21 and the minimum widths W3 and W4
of the thin-wall portion 214. In FIG. 10, the first vertical
axis represents a maximum stress generated in the rotor core 21
(specifically a ratio as compared to the comparative example), 25 the second vertical axis represents a maximum magnetic force of
the rotor 2 (specifically a ratio as compared to the
comparative example), and the horizontal axis represents W3/T
and W4/T. In this embodiment, W3 is equal to W4.
In FIG. 10, the broken line F3 represents a maximum 30 stress generated in the rotor core 21 with respect to changes
in the minimum width W3 and the minimum width W4 in a case
where the maximum stress generated in the rotor core 21a of the
rotor 2a of the comparative example is 100%. In FIG. 10, the
14
solid line F4 represents a maximum magnetic force of the rotor
2 with respect to changes in the minimum widths W3 and W4 in
the case where the magnetic force of the rotor 2a of the
comparative example is 100%.
[0041] 5 As shown in FIG. 10, a ratio W3/T of the minimum width W3
to the thickness T of the electromagnetic steel sheet 20
preferably satisfies 0.6 ≤ W3/T ≤ 1.5. In addition, a ratio
W4/T of the minimum width W4 to the thickness of the
electromagnetic steel sheet 20 preferably satisfies 0.6 ≤ W4/T 10 ≤ 1.5. That is, the rotor 2 preferably satisfies 0.6 ≤ W3/T ≤
1.5 and 0.6 ≤ W4/T ≤ 1.5. Accordingly, stress generated in the
rotor core 21, especially the thin-wall portions 214, can be
reduced. In addition, since leakage flux in the thin-wall
portions 214 is reduced, significant decrease of magnetic force 15 of the rotor 2 can be suppressed. In this embodiment, since
the rotor 2 satisfies 0.6 ≤ W3/T ≤ 1.5 and 0.6 ≤ W4/T ≤1.5, the
advantages described above can be obtained.
[0042]
In particular, if the rotor 2 satisfies 0.6 ≤ W3/T ≤ 1.0 20 and 0.6 ≤ W4/T ≤ 1.0, stress generated in the rotor core 21,
especially the thin-wall portions 214, can be effectively
reduced. In addition, since leakage flux in the thin-wall
portions 214 is further reduced, a magnetic force of the rotor
2 can be enhanced. 25 [0043]
FIG. 11 is a diagram illustrating another example of the
rotor core 21.
As illustrated in FIG. 11, the rotor core 21,
specifically each electromagnetic steel sheet 20, may further 30 include at least one hole 215. Each hole 215 extends in the
axial direction. In the xy plane, each hole 215 is circular.
For example, in the case of using the motor 1 as a driving
source of the compressor, each hole 215 is used as a through
15
hole through which a refrigerant passes in the compressor.
[0044]
A relationship between a diameter φ and a distance r
satisfies φ/4 ≤ r, where φ is a diameter R1 of the
electromagnetic steel sheet 20 (i.e., the rotor core 21) and r 5 is a distance from the axis line Ax (i.e., rotation center of
the rotor 2) to the center of the hole 215 in the xy plane. It
is sufficient that the distance r from the axis line Ax to the
center of at least one hole 215 of the plurality of holes 215
is φ/4 or more. That is, the distance r only needs to be a 10 half or more of the radius of the electromagnetic steel sheet
20 (i.e., the rotor core 21). Accordingly, at least one hole
215 can be placed near the permanent magnets 22, and thus, the
permanent magnets 22 can be effectively cooled, and
demagnetization of the permanent magnets 22 can be suppressed. 15 [0045]
In the example illustrated in FIG. 11, with respect to
all the hole 215, the distance r from the axis line Ax to the
center of each hole 215 is φ/4 or more. In FIG. 11, a radius
R2 of a circle indicated by the broken line is φ/4. That is, 20 in FIG. 11, the center of all the holes 215 is located outside
a circle having the radius R2 indicated by the broken line.
Accordingly, the permanent magnets 22 can be more effectively
cooled, and demagnetization of the permanent magnets 22 can be
suppressed. 25 [0046]
Advantages of the rotor 2 will be described.
In the rotor 2, since the center rib 213 is formed on the
rotor core 21, a part of stress generated in the rotor 2 is
dispersed to the center rib 213, and thus stress generated in 30 the thin-wall portions 214 can be reduced. Accordingly,
deformation of the rotor core 21, especially the thin-wall
portions 214, can be prevented. That is, strength of the rotor
2 to the centrifugal force can be enhanced, and leakage flux in
16
the rotor 2 (especially the thin-wall portions 214) can be
reduced.
[0047]
In addition, in this embodiment, the rotor 2 satisfies T
≤ W1 ≤ 2×T. Accordingly, the first magnet insertion hole 211, 5 the second magnet insertion hole 212, and the center rib 213
can be easily formed by punching, and leakage flux in the
center rib 213 can be reduced.
[0048]
In addition, the rotor 2 satisfies 2 × T ≤ W2. 10 Accordingly, strength does not decrease in a region 213a of the
center rib 213. As a result, strength of the rotor 2
(especially the rotor core 21) can be increased.
[0049]
That is, since the rotor 2 satisfies T ≤ W1 ≤ 2 × T ≤ W2, 15 strength of the rotor 2 to the centrifugal force can be
enhanced, and leakage flux in the rotor 2 can be reduced. As a
result, a magnetic force of the rotor 2 can be enhanced, and
motor efficiency can be increased.
[0050] 20 If the rotor 2 satisfies W1 < W2 and 0.9 ≤ W1/T ≤ 1.9,
stress generated in the rotor core 21, especially the center
rib 213 and the thin-wall portions 214, can be reduced. In
addition, since leakage flux in the center rib 213 can be
reduced, a magnetic force of the rotor 2 can be enhanced. As a 25 result, motor efficiency can be further increased.
[0051]
In particular, since the rotor 2 satisfies W1 < W2 and
0.9 ≤ W1/T ≤ 1.5, stress applied to the rotor core 21,
especially the center rib 213 and the thin-wall portions 214 30 can be reduced, and a magnetic force of the rotor 2 can be
increased. As a result, motor efficiency can be further
increased.
[0052]
17
If the rotor 2 satisfies 0.6 ≤ W3/T ≤ 1.5 and 0.6 ≤ W4/T
≤ 1.5, stress generated in the rotor core 21, especially the
thin-wall portions 214, can be reduced. In addition, since
leakage flux in the thin-wall portions 214 is reduced,
significant decrease of a magnetic force of the rotor 2 can be 5 suppressed.
[0053]
In particular, if the rotor 2 satisfies 0.6 ≤ W3/T ≤ 1.0
and 0.6 ≤ W4/T ≤ 1.0, stress generated in the rotor core 21,
especially the thin-wall portions 214, can be effectively 10 reduced. In addition, since leakage flux in the thin-wall
portions 214 is further reduced, a magnetic force of the rotor
2 can be enhanced. As a result, motor efficiency can be
further increased.
[0054] 15 In addition, each electromagnetic steel sheet 20 further
includes at least one hole 215, and if the rotor 2 satisfies
φ/4 ≤ r, at least one hole 215 can be placed near the permanent
magnets 22. Thus, the permanent magnets 22 can be effectively
cooled, and demagnetization of the permanent magnets 22 can be 20 suppressed.
[0055]
Since the motor 1 according to the first embodiment
includes the rotor 2, the motor 1 can obtain the same
advantages as those of the rotor 2 described above. 25 [0056]
Since the motor 1 according to the first embodiment
includes the rotor 2, motor efficiency of the motor 1 can be
increased.
[0057] 30 In the case where the stator 3 includes at least one
notch 37, a space is formed between a housing of the compressor
and the notch 37, and this space is used as a channel through
which a refrigerant passes. Accordingly, the motor 1 can be
18
effectively cooled in the compressor.
[0058]
In the case where the stator 3 includes at least one hole
36, the hole 36 is used as a channel through which a
refrigerant passes in the compressor. Accordingly, the motor 1 5 can be effectively cooled in the compressor.
[0059]
SECOND EMBODIMENT
A compressor 6 according to a second embodiment of the
present invention will be described. 10 FIG. 12 is a cross-sectional view schematically
illustrating a structure of the compressor 6 according to the
second embodiment.
[0060]
The compressor 6 includes a motor 60 serving as an 15 electric element, a closed container 61 serving as a housing,
and a compression mechanism 62 serving as a compression element.
In this embodiment, the compressor 6 is a rotary compressor.
However, the compressor 6 is not limited to the rotary
compressor. 20 [0061]
The motor 60 is the motor 1 according to the first
embodiment. In this embodiment, the motor 60 is a permanent
magnet-embedded motor, but is not limited to this type.
[0062] 25 The closed container 61 covers the motor 60 and the
compression mechanism 62. In a bottom portion of the closed
container 61, refrigerating machine oil for lubricating a
sliding portion of the compression mechanism 62 is stored.
[0063] 30 The compressor 6 also includes a glass terminal 63 fixed
to the closed container 61, an accumulator 64, a suction pipe
65, and a discharge pipe 66.
[0064]
19
The compression mechanism 62 includes a cylinder 62a, a
piston 62b, an upper frame 62c (first frame), a lower frame 62d
(second frame), and a plurality of mufflers 62e individually
attached to the upper frame 62c and the lower frame 62d. The
compression mechanism 62 also includes a vane that divides the 5 inside of the cylinder 62a into a suction side and a
compression side. The compression mechanism 62 is driven by
the motor 60.
[0065]
The motor 60 is fixed in the closed container 61 by press 10 fitting or shrink fitting. A stator 3 may be directly attached
to the closed container 61 by welding, instead of press fitting
or shrink fitting.
[0066]
Electric power is supplied to a winding of the stator 3 15 of the motor 60 through the glass terminal 63.
[0067]
A rotor (specifically one end of a shaft 24) of the motor
60 is rotatably supported by a bearing provided on each of the
upper frame 62c and the lower frame 62d. 20 [0068]
The shaft 24 is inserted in the piston 62b. The shaft 24
is rotatably inserted in the upper frame 62c and the lower
frame 62d. The upper frame 62c and the lower frame 62d close
an end face of the cylinder 62a. The accumulator 64 supplies a 25 refrigerant (e.g., refrigerant gas) to the cylinder 62a through
the suction pipe 65.
[0069]
Next, an operation of the compressor 6 will be described.
A refrigerant supplied from the accumulator 64 is sucked into 30 the cylinder 62a from the suction pipe 65 fixed to the closed
container 61. The motor 60 rotates by electrification of an
inverter and consequently the piston 62b fitted to the shaft 24
rotates in the cylinder 62a. In this manner, the refrigerant
20
is compressed in the cylinder 62a.
[0070]
The Refrigerant passes through the mufflers 62e and rises
in the closed container 61. Refrigerating machine oil is mixed
in the compressed refrigerant. While the mixture of the 5 refrigerant and the refrigerating machine oil is passing
through a hole formed in a rotor core, separation between the
refrigerant and the refrigerating machine oil is promoted, and
accordingly, a flow of refrigerating machine oil into the
discharge pipe 66 can be prevented. In this manner, the 10 compressed refrigerant is supplied to a high-pressure side of a
refrigerant cycle through the discharge pipe 66.
[0071]
As a refrigerant of the compressor 6, R410A, R407C, or
R22, for example, can be used. However, the refrigerant of the 15 compressor 6 is not limited to these materials. For example,
as a refrigerant of the compressor 6, a refrigerant having a
small global warming potential (GWP) or the like may be used.
[0072]
Typical examples of the refrigerant having small GWPs 20 include refrigerants as follows:
[0073]
(1) Halogenated hydrocarbon including a carbon double
bond in a composition is, for example, HFO-1234yf (CF3CF=CH2).
HFO stands for Hydro-Fluoro-Olefin. Olefin is unsaturated 25 hydrocarbon having one double bond. The GWP of HFO-1234yf is 4.
[0074]
(2) Hydrocarbon having a carbon double bond in a
composition is, for example, R1270 (propylene). The GWP of the
R1270 is 3, which is smaller than the GWP of HFO-1234yf, but 30 flammability of R1270 is higher than flammability of HFO-1234yf.
[0075]
(3) A mixture including at least one of halogenated
hydrocarbon having a carbon double bond in a composition or
21
hydrocarbon having a carbon double bond in a composition is,
for example, a mixture of HFO-1234yf and R32. Since HFO-1234yf
is a low-pressure refrigerant, a pressure loss is large, and
performance in a refrigeration cycle (especially in an
evaporator) tends to degrade. Thus, it is preferable to use a 5 mixture with R32 or R41, each of which is a high-pressure
refrigerant, for example.
[0076]
The compressor 6 according to the second embodiment has
advantages described in the first embodiment. 10 [0077]
In addition, the use of the motor 1 according to the
first embodiment as the motor 60 can enhance efficiency of the
motor 60, and as a result, efficiency of the compressor 6 can
be enhanced. 15 [0078]
THIRD EMBODIMENT
An air conditioner 50 (also referred to as a
refrigerating air conditioner or a refrigeration cycle device)
according to a third embodiment of the present invention will 20 be described.
FIG. 13 is a diagram schematically illustrating a
configuration of the air conditioner 50 according to the third
embodiment.
[0079] 25 The air conditioner 50 according to the third embodiment
includes an indoor unit 51 serving as an air blower (first air
blower), a refrigerant pipe 52, and an outdoor unit 53 serving
as an air blower (second air blower) connected to the indoor
unit 51 through the refrigerant pipe 52. 30 [0080]
The indoor unit 51 includes a motor 51a (e.g., the motor
1 according to the first embodiment), an air blow unit 51b that
is driven by the motor 51a to thereby send air, and a housing
22
51c covering the motor 51a and the air blow unit 51b. The air
blow unit 51b includes a blade 51d that is driven by the motor
51a, for example. For example, the blade 51d is fixed to a
shaft (e.g., a shaft 24) of the motor 51a, and generates an
airflow. 5 [0081]
The outdoor unit 53 includes a motor 53a (e.g., the motor
1 according to the first embodiment), an air blow unit 53b, a
compressor 54, and a heat exchanger (not shown). The air blow
unit 53b is driven by the motor 53a to thereby send air. The 10 air blow unit 53b includes a blade 53d that is driven by the
motor 53a, for example. For example, the blade 53d is fixed to
a shaft (e.g., a shaft 24) of the motor 53a, and generates an
airflow. The compressor 54 includes a motor 54a (e.g., the
motor 1 according to the first embodiment), a compression 15 mechanism 54b (e.g., a refrigerant circuit) that is driven by
the motor 54a, and a housing 54c covering the motor 54a and the
compression mechanism 54b. The compressor 54 is, for example,
the compressor 6 described in the second embodiment.
[0082] 20 In the air conditioner 50, at least one of the indoor
unit 51 or the outdoor unit 53 includes the motor 1 described
in the first embodiment. Specifically, as a driving source of
the air blow unit, the motor 1 described in the first
embodiment is applied to at least one of the motors 51a or 53a. 25 As the motor 54a of the compressor 54, the motor 1 described in
the first embodiment may be used.
[0083]
The air conditioner 50 can perform operations such as a
cooling operation of sending cold air from the indoor unit 51 30 or a heating operation of sending hot air from the indoor unit
51, for example. In the indoor unit 51, the motor 51a is a
driving source for driving the air blow unit 51b. The air blow
unit 51b can send conditioned air.
23
[0084]
In the air conditioner 50 according to the third
embodiment, since the motor 1 described in the first embodiment
is applied to at least one of the motors 51a or 53a, the same
advantages as those described in the first embodiment can be 5 obtained. Accordingly, efficiency of the air conditioner 50
can be enhanced.
[0085]
In addition, as a driving source of an air blower (e.g.,
the indoor unit 51), the motor 1 according to the first 10 embodiment is used. Thus, the same advantages as those
described in the first embodiment can be obtained. In this
manner, efficiency of the air blower can be enhanced. An air
blower including the motor 1 according to the first embodiment
and the blade (e.g., the blade 51d or 53d) driven by the motor 15 1 can be used singly as a device for sending air. This air
blower is also applicable to devices other than the air
conditioner 50.
[0086]
The use of the motor 1 according to the first embodiment 20 as a driving source of the compressor 54 can obtain the same
advantages as those described in the first embodiment.
Accordingly, efficiency of the compressor 54 can be enhanced.
[0087]
The motor 1 described in the first embodiment can be 25 mounted on equipment including a driving source, such as a
ventilator, household electrical appliance, or a machine tool,
other than the air conditioner 50.
[0088]
Features of the embodiments described above may be 30 combined as appropriate.
DESCRIPTION OF REFERENCE CHARACTERS
[0089]
1, 51a, 54a, 60 motor, 2 rotor, 3 stator, 6 compressor,
24
20 electromagnetic steel sheet, 21 rotor core, 22 permanent
magnet, 33 slot, 34 tooth, 35 yoke, 36, 215 hole, 37 notch, 50
air conditioner (refrigeration and air-conditioning device),
210 magnet insertion hole, 211 first magnet insertion hole,
211a magnet placement portion, 211b flux barrier, 212 second 5 magnet insertion hole, 213 center rib, 214 thin-wall portion.
25
We Claim :
1. A rotor comprising:
an electromagnetic steel sheet including a first magnet
insertion hole, a second magnet insertion hole, and a center 5 rib between the first magnet insertion hole and the second
magnet insertion hole, the first magnet insertion hole and the
second magnet insertion hole being arranged in a V shape in a
plane orthogonal to an axial direction;
a first permanent magnet disposed in the first magnet 10 insertion hole; and
a second permanent magnet disposed in the second magnet
insertion hole, wherein
the rotor satisfies T ≤ W1 ≤ 2 × T ≤ W2,
where T is a thickness of the electromagnetic steel sheet, W1 15 is a minimum width of the center rib in a direction orthogonal
to a radial direction, and W2 is a maximum width of the center
rib in the direction orthogonal to the radial direction.
2. The rotor according to claim 1, wherein the rotor 20 satisfies W1 < W2 and 0.9 ≤ W1/T ≤ 1.9.
3. The rotor according to claim 1, wherein the rotor
satisfies W1 < W2 and 0.9 ≤ W1/T ≤ 1.5.
25 4. The rotor according to any one of claims 1 to 3, wherein
the electromagnetic steel sheet includes a first thinwall
portion between an outer peripheral surface of the
electromagnetic steel sheet and the first magnet insertion hole,
the electromagnetic steel sheet includes a second thin- 30 wall portion between the outer peripheral surface of the
electromagnetic steel sheet and the second magnet insertion
hole,
the first magnet insertion hole includes a first flux
26
barrier that is a space between the first permanent magnet and
the first thin-wall portion,
the second magnet insertion hole includes a second flux
barrier that is a space between the second permanent magnet and
the second thin-wall portion, and 5 the rotor satisfies 0.6 ≤ W3/T ≤ 1.5 and 0.6 ≤ W4/T ≤ 1.5,
where in the plane, W3 is a minimum width of the first thinwall
portion in a first radial direction and W4 is a minimum
width of the second thin-wall portion in a second radial
direction. 10
5. The rotor according to claim 4, wherein the rotor
satisfies 0.6 ≤ W3/T ≤ 1.0 and 0.6 ≤ W4/T ≤ 1.0.
6. The rotor according to any one of claims 1 to 5, wherein 15 the electromagnetic steel sheet includes a hole extending
in the axial direction, and
the rotor satisfies φ/4 ≤ r,
where φ is a diameter of the electromagnetic steel sheet and r
is a distance from a rotation center of the rotor to a center 20 of the hole in the plane.
7. A motor comprising:
a stator; and
a rotor disposed inside the stator, wherein 25 the rotor includes
an electromagnetic steel sheet including a first magnet
insertion hole, a second magnet insertion hole, and a center
rib between the first magnet insertion hole and the second
magnet insertion hole, the first magnet insertion hole and the 30 second magnet insertion hole being arranged in a V shape in a
plane orthogonal to an axial direction,
a first permanent magnet disposed in the first magnet
insertion hole, and
27
a second permanent magnet disposed in the second magnet
insertion hole, and
the motor satisfies T ≤ W1 ≤ 2 × T ≤ W2,
where T is a thickness of the electromagnetic steel sheet, W1
is a minimum width of the center rib in a direction orthogonal 5 to a radial direction, and W2 is a maximum width of the center
rib in the direction orthogonal to the radial direction.
8. The motor according to claim 7, wherein the stator
includes at least one notch formed on an outer peripheral 10 surface of the stator.
9. The motor according to claim 7 or 8, wherein the stator
includes at least one hole extending in the axial direction.
15 10. A compressor comprising:
a motor;
a compression mechanism to be driven by the motor; and
a housing covering the motor and the compression
mechanism, wherein 20 the motor includes
a stator, and
a rotor disposed inside the stator,
the rotor includes
an electromagnetic steel sheet including a first magnet 25 insertion hole, a second magnet insertion hole, and a center
rib between the first magnet insertion hole and the second
magnet insertion hole, the first magnet insertion hole and the
second magnet insertion hole being arranged in a V shape in a
plane orthogonal to an axial direction, 30 a first permanent magnet disposed in the first magnet
insertion hole, and
a second permanent magnet disposed in the second magnet
insertion hole, and
28
the compressor satisfies T ≤ W1 ≤ 2 × T ≤ W2
where T is a thickness of the electromagnetic steel sheet, W1
is a minimum width of the center rib in a direction orthogonal
to a radial direction, and W2 is a maximum width of the center
rib in the direction orthogonal to the radial direction. 5
11. A refrigeration and air-conditioning device comprising:
an indoor unit; and
an outdoor unit connected to the indoor unit, wherein
at least one of the indoor unit or the outdoor unit 10 includes a motor,
the motor includes
a stator, and
a rotor disposed inside the stator,
the rotor includes 15 an electromagnetic steel sheet including a first magnet
insertion hole, a second magnet insertion hole, and a center
rib between the first magnet insertion hole and the second
magnet insertion hole, the first magnet insertion hole and the
second magnet insertion hole being arranged in a V shape in a 20 plane orthogonal to an axial direction,
a first permanent magnet disposed in the first magnet
insertion hole, and
a second permanent magnet disposed in the second magnet
insertion hole, and 25 the refrigeration and air-conditioning device satisfies T
≤ W1 ≤ 2 × T ≤ W2
where T is a thickness of the electromagnetic steel sheet, W1
is a minimum width of the center rib in a direction orthogonal
to a radial direction, and W2 is a maximum width of the center 30
29
rib in the direction orthogonal to the radial direction.