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

2
DESCRIPTION
TECHNICAL FIELD
[0001]
5 The present disclosure relates to a rotor, a motor, a
blower and an air conditioner.
BACKGROUND ART
[0002]
As a rotor used for a motor, there has been proposed a
10 rotor including two types of permanent magnets (see Patent
References 1 and 2, for example).
[0003]
The rotor described in Patent References 1 and 2
includes a first permanent magnet supported by a rotary shaft
15 and a second permanent magnet supported by an outer periphery
of the first permanent magnet and having a magnetic pole
stronger than a magnetic pole of the first permanent magnet.
In Patent References 1 and 2, the second permanent magnet
forms an outer circumference of the rotor. With this
20 configuration, the magnetic flux amount of magnetic flux
flowing from the rotor to the stator of the motor can be
increased.
PRIOR ART REFERENCE
PATENT REFERENCE
25 [0004]
Patent Reference 1: Japanese Patent Application
Publication No. 2005-151757
Patent Reference 2: Japanese Patent Application
Publication No. 2011-087393
30 SUMMARY OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
[0005]
However, a permanent magnet having a strong magnetic

3
pole is generally expensive. Thus, the manufacturing cost of
the rotor increases in a case where the second permanent
magnet having a magnetic pole stronger than a magnetic pole of
the first permanent magnet forms the whole outer circumference
5 of the rotor.
[0006]
An object of the present disclosure is to secure a
sufficient magnetic flux amount of magnetic flux generated in
the rotor while reducing the manufacturing cost of the rotor.
10 MEANS FOR SOLVING THE PROBLEM
[0007]
A rotor according to an aspect of the present disclosure
includes a rotary shaft, a first permanent magnet supported by
the rotary shaft, and a second permanent magnet supported by
15 an outer periphery of the first permanent magnet and having a
magnetic pole stronger than a magnetic pole of the first
permanent magnet. The second permanent magnet includes a
plurality of magnet parts arranged at intervals in a
circumferential direction of the first permanent magnet. A
20 first width as a width in the circumferential direction of
each of the plurality of magnet parts at a central part of the
first permanent magnet in an axial direction of the rotary
shaft is wider than a second width as a width in the
circumferential direction of each of the magnet parts at an
25 end part of the first permanent magnet in the axial direction.
EFFECT OF THE INVENTION
[0008]
According to the present disclosure, a sufficient
magnetic flux amount of magnetic flux generated in the rotor
30 can be secured while reducing the manufacturing cost of the
rotor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009]
FIG. 1 is a plan view showing the configuration of a

4
motor according to a first embodiment.
FIG. 2 is a side view showing the configuration of a
rotor shown in FIG. 1 and part of the configuration of a
stator.
5 FIG. 3 is a plan view showing the configuration of the
rotor shown in FIG. 2.
FIG. 4 is a plan view showing the configuration of a
ferrite bond magnet shown in FIG. 3.
FIG. 5 is a sectional view showing the configuration of
10 the rotor according to the first embodiment.
FIG. 6 is a sectional view of the ferrite bond magnet
shown in FIG. 5 taken along the line A6 - A6.
FIG. 7 is a flowchart showing a manufacturing process of
the rotor according to the first embodiment.
15 FIG. 8 is a flowchart showing a manufacturing process of
a rotor body according to the first embodiment.
FIG. 9 is a plan view showing the configuration of a
rotor according to a first comparative example.
FIG. 10(A) is a side view showing the configuration of a
20 rotor according to a second comparative example.
FIG. 10(B) is a sectional view showing the configuration
of the rotor according to the second comparative example.
FIG. 11 is a graph showing distribution of the surface
magnetic flux density of the rotor according to the first
25 comparative example and distribution of the surface magnetic
flux density of the rotor according to the second comparative
example.
FIG. 12 is a graph showing distribution of the surface
magnetic flux density of the rotor according to the first
30 embodiment and the distribution of the surface magnetic flux
density of the rotor according to the first comparative
example.
FIG. 13 is a side view showing the configuration of a
rotor according to a second embodiment.

5
FIG. 14 is a plan view showing the configuration of a
rotor according to a third embodiment.
FIG. 15 is a sectional view showing the configuration of
a rotor according to a fourth embodiment.
5 FIG. 16 is a sectional view of the rotor shown in FIG.
15 taken along the line A16 - A16.
FIG. 17 is a sectional view showing the configuration of
a rotor according to a fifth embodiment.
FIG. 18 is a partial sectional view showing the
10 configuration of the rotor shown in FIG. 17.
FIG. 19 is a partial sectional view showing the
configuration of a rotor according to a sixth embodiment.
FIG. 20 is a sectional view showing the configuration of
a rotor according to a seventh embodiment.
15 FIG. 21 is a plan view showing the configuration of a
rotor according to an eighth embodiment.
FIG. 22 is a side view showing the configuration of the
rotor according to the eighth embodiment.
FIG. 23 is a sectional view of the rotor shown in FIG.
20 21 taken along the line A23 - A23.
FIG. 24 is a plan view showing the configuration of a
rotor according to a first modification of the eighth
embodiment.
FIG. 25 is a sectional view of the rotor shown in FIG.
25 24 taken along the line A25 - A25.
FIG. 26 is a diagram schematically showing the
configuration of an air conditioner according to a ninth
embodiment.
MODE FOR CARRYING OUT THE INVENTION
30 [0010]
A rotor, a motor, a blower and an air conditioner
according to each embodiment of the present disclosure will be
described below with reference to the drawings. The following
embodiments are just examples and it is possible to

6
appropriately combine the embodiments and appropriately modify
each embodiment.
[0011]
An xyz orthogonal coordinate system is shown as needed
5 in each drawing in order to facilitate the understanding of
descriptions regarding the configuration of the rotor or the
like shown in the drawing. A z-axis is a coordinate axis
parallel to an axis C1 of the rotor. An x-axis is a coordinate
axis orthogonal to the z-axis. A y-axis is a coordinate axis
10 orthogonal to both of the x-axis and the z-axis.
[0012]
(First Embodiment)
FIG. 1 is a plan view showing the configuration of a
motor 100 according to a first embodiment. The motor 100 is a
15 permanent magnet synchronous motor, for example. The motor 100
includes a rotor 1 and a stator 9. The rotor 1 is disposed on
an inner side of the stator 9. Namely, the motor 100 is a
motor of the inner rotor type. An air gap G is formed between
the rotor 1 and the stator 9. The air gap G is a gap of 0.5
20 mm, for example.
[0013]
The rotor 1 includes a shaft 10 as a rotary shaft. The
shaft 10 extends in the z-axis direction. In the following
description, the z-axis direction is also referred to as an
25 "axial direction". The direction along a circumference of a
circle centering at the axis C1 of the shaft 10 (for example,
as shown by the arrow R1 in FIG. 1) is referred to as a
"circumferential direction". The direction of a straight line
orthogonal to the z-axis direction and passing through the
30 axis C1 is referred to as a "radial direction". The rest of
the configuration of the rotor 1 will be described later.
[0014]
(Stator)
The stator 9 includes a stator core 91 and a coil 92

7
wound on the stator core 91. The stator core 91 includes a
yoke 91a in a ring shape about the axis C1 and a plurality of
teeth 91b extending inward in the radial direction from the
yoke 91a. The plurality of teeth 91b are arranged at equal
5 angular intervals in the circumferential direction R1. A tip
end part of each tooth 91b on the inner side in the radial
direction faces an outer circumference 1a of the rotor 1 via
the air gap G. While the number of teeth 91b is 12 in FIG. 1,
the number of teeth 91b is not limited to 12 but may be set at
10 any number.
[0015]
(Rotor)
FIG. 2 is a side view showing the configuration of the
rotor 1 and part of the configuration of the stator 9
15 according to the first embodiment. FIG. 3 is a plan view
showing the configuration of the rotor 1 shown in FIG. 2. As
shown in FIGS. 2 and 3, the rotor 1 includes the shaft 10, a
ferrite bond magnet 20 as a first permanent magnet, and a
rare-earth bond magnet 30 as a second permanent magnet.
20 [0016]
As shown in FIG. 2, in the first embodiment, the length
L1 of the rotor 1 in the axial direction is longer than the
length L9 of the stator core 91 of the stator 9 in the axial
direction. With this configuration, the magnetic flux amount
25 of interlinkage magnetic flux flowing from the permanent
magnets (i.e., the ferrite bond magnet 20 and the rare-earth
bond magnet 30) of the rotor 1 to the coil 92 of the stator 9
can be increased.
[0017]
30 The ferrite bond magnet 20 is supported by the shaft 10.
The ferrite bond magnet 20 contains a ferrite magnet and a
resin. The resin contained in the ferrite bond magnet 20 is
nylon resin, PPS (Poly Phenylene Sulfide) resin, epoxy resin
or the like, for example.

8
[0018]
The rare-earth bond magnet 30 is supported by an outer
periphery 20a of the ferrite bond magnet 20. The rare-earth
bond magnet 30 contains a rare-earth magnet and a resin. The
5 rare-earth magnet is a neodymium magnet containing neodymium
(Nd), iron (Fe) and boron (B), a samarium-iron-nitrogen magnet
containing samarium (Sm), Fe and nitrogen (N), or the like,
for example. The resin contained in the rare-earth bond magnet
30 is nylon resin, PPS resin, epoxy resin or the like, for
10 example, similarly to the resin contained in the ferrite bond
magnet 20.
[0019]
The ferrite bond magnet 20 and the rare-earth bond
magnet 30 differ from each other in strength (i.e., quantity
15 of magnetism) of a magnetic pole. Specifically, the rare-earth
bond magnet 30 has a magnetic pole stronger than a magnetic
pole of the ferrite bond magnet 20. In other words, magnetic
force of the rare-earth bond magnet 30 is greater than
magnetic force of the ferrite bond magnet 20. Further, the
20 ferrite bond magnet 20 and the rare-earth bond magnet 30
differ from each other in the linear expansion coefficient.
[0020]
FIG. 4 is a plan view showing the configuration of the
ferrite bond magnet 20 shown in FIG. 3. As shown in FIG. 4, a
25 two-dimensional shape of the ferrite bond magnet 20 parallel
to an xy plane is a ring shape about the axis C1. The outer
periphery 20a of the ferrite bond magnet 20 forms part of the
outer circumference 1a (see FIG. 1) of the rotor 1. The
ferrite bond magnet 20 has a plurality of groove parts 21
30 arranged at intervals in the circumferential direction R1
about the axis C1. The plurality of groove parts 21 are
disposed at positions at equal angles in the circumferential
direction R1 about the axis C1. Each groove part 21 is
recessed from the outer periphery 20a toward an inner

9
circumference 20b of the ferrite bond magnet 20. The groove
part 21 is an oblong groove that is elongated in the axial
direction.
[0021]
5 The ferrite bond magnet 20 is oriented to have polar
anisotropy. Accordingly, the plurality of groove parts 21
include south pole groove parts 21a and north pole groove
parts 21b. Namely, a plurality of groove parts 21a and 21b
adjacent to each other in the circumferential direction R1
10 have magnetic poles different from each other in the polarity.
The arc-like arrow F2 shown in FIG. 4 indicates the direction
of magnetic flux in the ferrite bond magnet 20. Magnetic flux
flowing in from the outer side of the south pole groove part
21a in the radial direction advances to the north pole groove
15 part 21b adjacent thereto in the circumferential direction R1.
Thus, the rotor 1 (see FIG. 2) is not required to have a rotor
core that forms a magnetic path on the inner side of the
ferrite bond magnet 20 in the radial direction. Accordingly,
the number of components in the rotor 1 can be reduced and the
20 weight of the rotor 1 can be reduced.
[0022]
As shown in FIG. 3, in the first embodiment, the ferrite
bond magnet 20 is supported by the shaft 10 via a resin part
60. The resin part 60 is formed of unsaturated polyester
25 resin, for example. The resin part 60 includes an inner
cylinder part 61, an outer cylinder part 62 and a plurality of
(four in the first embodiment) ribs 63. The inner cylinder
part 61 has a cylindrical shape and is fixed to an outer
circumference 10a of the shaft 10. The outer cylinder part 62
30 has a cylindrical shape and is fixed to the inner
circumference 20b of the ferrite bond magnet 20. The plurality
of ribs 63 connect the inner cylinder part 61 and the outer
cylinder part 62 to each other. The plurality of ribs 63
radially extend outward in the radial direction from the inner

10
cylinder part 61. The plurality of ribs 63 are disposed at
positions at equal angles in the circumferential direction R1
about the axis C1. Incidentally, the ferrite bond magnet 20
may also be fixed to the shaft 10 directly via no resin part
5 60.
[0023]
The rare-earth bond magnet 30 includes a plurality of
rare-earth magnet parts 31 as a plurality of magnet parts
arranged at intervals in the circumferential direction R1. An
10 outer periphery 31a of each of the plurality of rare-earth
magnet parts 31 forms a part of the outer circumference 1a
(see FIG. 1) of the rotor 1. The outer periphery 31a and an
inner periphery 31b of the rare-earth magnet part 31 are
situated on concentric circles. Namely, the thickness of the
15 rare-earth magnet part 31 in the radial direction is constant
in the circumferential direction R1.
[0024]
Each of the plurality of rare-earth magnet parts 31 is
oriented to have the polar anisotropy. A plurality of rare20 earth magnet parts 31 adjacent to each other in the
circumferential direction R1 have magnetic poles different
from each other in the polarity. The arc-like arrows F3 shown
in FIG. 3 indicate the directions of magnetic flux in the
rare-earth magnet parts 31. Magnetic flux flowing in from the
25 outer side of the south pole rare-earth magnet part 31 in the
radial direction advances to the north pole rare-earth magnet
part 31 adjacent thereto in the circumferential direction R1.
In the first embodiment, the rotor 1 has 8 magnetic poles
since the rare-earth bond magnet 30 includes 8 rare-earth
30 magnet parts 31. Incidentally, the number of magnetic poles of
the rotor 1 is not limited to 8. It is sufficient that the
number of magnetic poles of the rotor 1 is 2n or more. The
number n is a natural number greater than or equal to 1.
[0025]

11
The rare-earth magnet parts 31 are disposed in the
groove parts 21 (see FIG. 4) of the ferrite bond magnet 20.
The ferrite bond magnet 20 and the rare-earth magnet parts 31
are joined to each other. In the first embodiment, the rare5 earth magnet parts 31 are jointed to the groove parts 21 of
the ferrite bond magnet 20 by integral molding (referred to
also as "two-color molding") of the ferrite bond magnet 20 and
the rare-earth bond magnet 30. With this configuration, a
rotor body 50 including the ferrite bond magnet 20 and the
10 rare-earth bond magnet 30 is formed.
[0026]
In the first embodiment, the integral molding of the
ferrite bond magnet 20 and the rare-earth bond magnet 30 means
that the rare-earth bond magnet 30 is molded in a state in
15 which the ferrite bond magnet 20 manufactured previously is
placed in a mold. Thus, as compared to a configuration in
which the ferrite bond magnet 20 is molded in a state in which
the rare-earth bond magnet 30 (i.e., the plurality of rareearth magnet parts 31) is placed in the mold, work of placing
20 a plurality of (8 in the first embodiment) rare-earth magnet
parts 31 in the mold can be eliminated, and therefore the
productivity of the rotor body 50 can be increased.
[0027]
As shown in FIG. 2, a central part 20c of the ferrite
25 bond magnet 20 in the axial direction faces the stator core 91
in the radial direction. Further, a width in the
circumferential direction of each of the plurality of rareearth magnet parts 31 gradually increases from each end part
20d toward the central part 20c of the ferrite bond magnet 20
30 in the axial direction. A first width W1 represents a width in
the circumferential direction of each rare-earth magnet part
31 in the central part 20c of the ferrite bond magnet 20 in
the axial direction. A second width W2 represents a width in
the circumferential direction of each rare-earth magnet part

12
31 in the end part 20d of the ferrite bond magnet 20 in the
axial direction. The first width W1 is wider than the second
width W2. Namely, the first width W1 and the second width W2
satisfy the following expression (1):
5 W1 > W2 (1)
With this configuration, a magnetic pole of the rareearth magnet part 31 at the central part 20c of the ferrite
bond magnet 20 facing the stator core 91 in the radial
direction is made stronger than a magnetic pole of the rare10 earth magnet part 31 at the end part 20d of the ferrite bond
magnet 20 in the axial direction. Therefore, a sufficient
magnetic flux amount of the magnetic flux generated in the
rotor 1 can be secured.
[0028]
15 Here, when the length L1 of the rotor 1 in the axial
direction is longer than the length L9 of the stator core 91
in the axial direction, there is a case where leakage flux is
included in magnetic flux flowing from an end part of the
rotor 1 in the axial direction (i.e., end part 1d shown in
20 FIG. 5 which will be described later) to the stator 9.
According to the first embodiment, since the first width W1 is
wider than the second width W2 as described above, the
magnetic pole of the rare-earth magnet part 31 at the central
part 20c of the ferrite bond magnet 20 in the axial direction
25 is made stronger than the magnetic pole of the rare-earth
magnet part 31 at the end part 20d of the ferrite bond magnet
20 in the axial direction. Therefore, a sufficient magnetic
flux amount of magnetic flux flowing from the rotor 1 to the
stator 9 can be secured.
30 [0029]
FIG. 5 is a sectional view showing the configuration of
the rotor 1 according to the first embodiment. As shown in
FIG. 5, the ferrite bond magnet 20 includes a first ferrite
magnet part 41 as a first split magnet part and a second

13
ferrite magnet part 42 as a second split magnet part. The
first ferrite magnet part 41 and the second ferrite magnet
part 42 are aligned in the axial direction. Namely, in the
first embodiment, the ferrite bond magnet 20 is split into two
5 magnet parts at the central part 20c in the axial direction.
In the axial direction, the first ferrite magnet part 41 and
the second ferrite magnet part 42 are in contact with each
other. Incidentally, the shaft 10 (see FIG. 2) is not shown in
FIG. 5.
10 [0030]
FIG. 6 is a sectional view showing the ferrite bond
magnet 20 shown in FIG. 5 taken along the line A6 - A6. Here,
the line A6 - A6 shown in FIG. 5 is a straight line passing
through the central part 20c (see FIG. 2) of the ferrite bond
15 magnet 20 in the axial direction. Namely, FIG. 6 is a
sectional view showing the configuration of the central part
20c of the ferrite bond magnet 20 in the axial direction.
[0031]
As shown in FIGS. 4 and 6, a width W21 represents a
20 width in the circumferential direction R1 of the groove part
21 in the central part 20c of the ferrite bond magnet 20 in
the axial direction. A width W22 represents a width in the
circumferential direction of the groove part 21 in the end
part 20d of the ferrite bond magnet 20 in the axial direction.
25 The width W21 is wider than the width W22. Namely, the width
W21 and the width W22 satisfy the following expression (2):
W21 > W22 (2)
Further, the width W21 equals the first width W1 shown
in FIG. 2, and the width W22 equals the second width W2 shown
30 in FIG. 2. Namely, the shape of the groove part 21 of the
ferrite bond magnet 20 corresponds to the shape of the rareearth magnet part 31.
[0032]
Next, a manufacturing method of the rotor 1 will be

14
described with reference to FIG. 7. FIG. 7 is a flowchart
showing a manufacturing process of the rotor 1. In the
manufacturing process of the rotor 1, a magnetizer is used.
[0033]
5 In step ST1, the rotor body 50 is formed. Incidentally,
details of the step ST1 will be described later.
[0034]
In step ST2, the rotor body 50 is connected to the shaft
10. In the first embodiment, the rotor body 50 is connected to
10 the shaft 10 by integrating the rotor body 50 and the shaft 10
together via the resin part 60.
[0035]
In step ST3, the rotor body 50 is magnetized by using
the magnetizer, for example. Specifically, the ferrite bond
15 magnet 20 and the rare-earth bond magnet 30 are magnetized so
that the ferrite bond magnet 20 and the rare-earth bond magnet
30 have the polar anisotropy.
[0036]
Next, the details of the process of forming the rotor
20 body 50 (i.e., the step ST1 shown in FIG. 7) will be described
with reference to FIG. 8. FIG. 8 is a flowchart showing the
process of forming the rotor body 50. In the process of
forming the rotor body 50, a first mold for molding the first
ferrite magnet part 41 and the second ferrite magnet part 42,
25 a second mold for molding the rare-earth bond magnet 30, and a
magnet for the orientation are used.
[0037]
In step ST11, the inside of the first mold for molding
the first ferrite magnet part 41 and the second ferrite magnet
30 part 42 is filled with the material of the first ferrite
magnet part 41 and the second ferrite magnet part 42. The
first ferrite magnet part 41 and the second ferrite magnet
part 42 are molded by injection molding, for example.
Incidentally, the method of molding the first ferrite magnet

15
part 41 and the second ferrite magnet part 42 is not limited
to injection molding. The first ferrite magnet part 41 and the
second ferrite magnet part 42 may be molded by a different
molding method such as press molding.
5 [0038]
In step ST12, the first ferrite magnet part 41 and the
second ferrite magnet part 42 having predetermined shapes are
molded while orienting the material of the first ferrite
magnet part 41 and the second ferrite magnet part 42. In the
10 step ST12, the first ferrite magnet part 41 and the second
ferrite magnet part 42 are molded while orienting the material
of the first ferrite magnet part 41 and the second ferrite
magnet part 42 in a state in which a magnetic field having the
polar anisotropy is generated inside the first mold by using
15 the magnet for the orientation, for example. With this step,
the ferrite bond magnet 20 having the polar anisotropy is
molded. Further, in the step ST12, the molding is carried out
so that an end face 41a of the first ferrite magnet part 41
and an end face 42a of the second ferrite magnet part 42 face
20 the +z-axis direction.
[0039]
In step ST13, the first ferrite magnet part 41 and the
second ferrite magnet part 42 which are molded are cooled
down.
25 [0040]
In step ST14, the first ferrite magnet part 41 and the
second ferrite magnet part 42 are taken out of the first mold.
[0041]
In step ST15, the first ferrite magnet part 41 and the
30 second ferrite magnet part 42 taken out in the step ST14 are
demagnetized.
[0042]
In step ST16, the first ferrite magnet part 41 and the
second ferrite magnet part 42 are placed inside the second

16
mold for the injection molding of the rare-earth bond magnet
30. In the step ST16, the first ferrite magnet part 41 and the
second ferrite magnet part 42 are placed inside the second
mold so that the end face 41a of the first ferrite magnet part
5 41 in the axial direction and the end face 42a of the second
ferrite magnet part 42 in the axial direction contact each
other. Namely, in the step ST16, the end face 41a of the first
ferrite magnet part 41 is stuck to the end face 42a of the
second ferrite magnet part 42 by inverting the first ferrite
10 magnet part 41 molded in the step ST12 in the axial direction.
Further, in the first embodiment, work of positioning the
first ferrite magnet part 41 and the second ferrite magnet
part 42 can be facilitated since the groove parts 21 are
formed in the part of the ferrite bond magnet 20 where the end
15 face 41a and the end face 42a contact each other (i.e., the
central part 20c in the axial direction).
[0043]
In step ST17, the groove parts 21 of the ferrite bond
magnet 20 placed in the second mold are filled with the
20 material of the rare-earth bond magnet 30. The rare-earth bond
magnet 30 is molded by injection molding, for example.
Incidentally, the method of molding the rare-earth bond magnet
30 is not limited to injection molding. The rare-earth bond
magnet 30 may be molded by a different molding method such as
25 press molding.
[0044]
In step ST18, the rare-earth bond magnet 30 having a
predetermined shape is molded while orienting the material of
the rare-earth bond magnet 30. In the step ST18, the rare30 earth bond magnet 30 (i.e., the plurality of rare-earth magnet
parts 31) is molded while orienting the material of the rareearth bond magnet 30 in a state in which a magnetic field
having the polar anisotropy is generated inside the second
mold by using the magnet for the orientation, for example.

17
With this step, the rotor body 50 in which the ferrite bond
magnet 20 and the rare-earth bond magnet 30 are molded
integrally is formed.
[0045]
5 In step ST19, the rotor body 50 formed in the step ST18
is cooled down.
[0046]
In step ST20, the rotor body 50 cooled down is taken out
of the second mold.
10 [0047]
In step ST21, the rotor body 50 taken out in the step
ST20 is demagnetized.
[0048]
Next, a manufacturing cost of the rotor 1 according to
15 the first embodiment will be described while making a
comparison with a rotor 101a according to a first comparative
example. FIG. 9 is a plan view showing the configuration of
the rotor 101a according to the first comparative example.
Incidentally, the shaft 10 is not shown in FIG. 9.
20 [0049]
As shown in FIG. 9, in the rotor 101a according to the
first comparative example, a rare-earth bond magnet 130a in a
ring shape is disposed on an outer circumference 120c of a
ferrite bond magnet 120a in a ring shape. Namely, in the rotor
25 101a according to the first comparative example, the whole of
an outer circumference 101c of the rotor 101a is formed by the
rare-earth bond magnet 130a.
[0050]
In contrast, in the first embodiment, as shown in FIG. 2
30 described above, the outer circumference 1a of the rotor 1 is
formed by the outer periphery 20a of the ferrite bond magnet
20 and the outer peripheries 31a of the plurality of rareearth magnet parts 31 of the rare-earth bond magnet 30. With
this configuration, in the rotor 1 according to the first

18
embodiment, the amount of use of the rare-earth bond magnet 30
can be reduced as compared to the rotor 101a according to the
first comparative example. Specifically, in the rotor 1
according to the first embodiment, the amount of use of the
5 rare-earth bond magnet 30 can be reduced by approximately 20 %
as compared to the rotor 101a according to the first
comparative example. The rare-earth bond magnet 30 is
expensive as compared to the ferrite bond magnet 20. For
example, the material unit price of the rare-earth bond magnet
10 30 is 10 times or more of the material unit price of the
ferrite bond magnet 20. The amount of use of the rare-earth
bond magnet 30 can be reduced since the outer circumference 1a
of the rotor 1 is formed by the outer periphery 20a of the
ferrite bond magnet 20 and the outer peripheries 31a of the
15 plurality of rare-earth magnet parts 31. Thus, the
manufacturing cost of the rotor 1 according to the first
embodiment can be reduced.
[0051]
Next, the surface magnetic flux density of the rotor 1
20 according to the first embodiment will be described while
making a comparison with the rotor 101a according to the first
comparative example and a rotor 101b according to a second
comparative example. FIG. 10(A) is a side view showing the
configuration of the rotor 101b according to the second
25 comparative example. FIG. 10(B) is a sectional view showing
the configuration of the rotor 101b according to the second
comparative example. Incidentally, the shaft 10 is not shown
in FIGS. 10(A) and 10(B).
[0052]
30 As shown in FIGS. 10(A) and 10(B), the rotor 101b
includes a ferrite bond magnet 120b and a rare-earth bond
magnet 130b. The rare-earth bond magnet 130b includes a
plurality of rare-earth magnet parts 131b arranged at
intervals in the circumferential direction R1. Thus, the

19
amount of use of the rare-earth bond magnet 130b in the rotor
101b according to the second comparative example is the same
as the amount of use of the rare-earth bond magnet 30 in the
rotor 1 according to the first embodiment and differs from the
5 amount of use of the rare-earth bond magnet 130a in the rotor
1 according to the first comparative example. Further, in the
rotor 101b according to the second comparative example, the
width W10 of the rare-earth magnet part 131b in the
circumferential direction R1 is constant in the axial
10 direction. Thus, the rotor 101b according to the second
comparative example differs from the rotor 1 according to the
first embodiment and the rotor 101a according to the first
comparative example in the shape of the rare-earth magnet part
131b. Furthermore, in the rotor 101b according to the second
15 comparative example, the ferrite bond magnet 120b is not split
in the axial direction. Thus, the rotor 101b according to the
second comparative example differs from the rotor 1 according
to the first embodiment in the shape of the ferrite bond
magnet 120b.
20 [0053]
FIG. 11 is a graph showing the distribution of the
surface magnetic flux density of the rotor 101a according to
the first comparative example and distribution of the surface
magnetic flux density of the rotor 101b according to the
25 second comparative example. In FIG. 11, the horizontal axis
represents a position in the circumferential direction R1
[deg.] on the outer circumference 101c of the rotor 101a or an
outer circumference 101d of the rotor 101b. The vertical axis
represents the surface magnetic flux density [a.u.]. Further,
30 in FIG. 11, the solid line indicates the distribution of the
surface magnetic flux density of the rotor 101a according to
the first comparative example and the broken line indicates
the distribution of the surface magnetic flux density of the
rotor 101b according to the second comparative example.

20
[0054]
As shown in FIG. 11, the distribution of the surface
magnetic flux density of the rotor 101a according to the first
comparative example is represented by a waveform S1 of an even
5 sinusoidal wave. Meanwhile, the distribution of the surface
magnetic flux density of the rotor 101b according to the
second comparative example is also represented by a waveform
S2 of a substantially sinusoidal wave being approximately
even. Namely, in the rotor 101b according to the second
10 comparative example, an abrupt change in the surface magnetic
flux density is inhibited in the circumferential direction R1
as compared to the rotor 101a according to the first
comparative example.
[0055]
15 FIG. 12 is a graph showing distribution of the surface
magnetic flux density of the rotor 1 according to the first
embodiment and the distribution of the surface magnetic flux
density of the rotor 101a according to the first comparative
example. In FIG. 12, the horizontal axis represents the
20 position in the circumferential direction R1 [deg.] on the
outer circumference 1a of the rotor 1 or the outer
circumference 101c of the rotor 101a. The vertical axis
represents the surface magnetic flux density [a.u.]. Further,
in FIG. 12, the solid line indicates the distribution of the
25 surface magnetic flux density in a central part 1c of the
rotor 1 according to the first embodiment in the axial
direction and the chain line indicates the distribution of the
surface magnetic flux density in the end part 1d of the rotor
1 according to the first embodiment in the axial direction.
30 Furthermore, in FIG. 12, the broken line indicates the
distribution of the surface magnetic flux density of the rotor
101a according to the first comparative example.
[0056]
As shown in FIG. 12, the distribution of the surface

21
magnetic flux density of the rotor 101a according to the first
comparative example is represented by the waveform S1 of the
even sinusoidal wave. Meanwhile, the distribution of the
surface magnetic flux density in the end part 1d of the rotor
5 1 according to the first embodiment in the axial direction is
also represented by a waveform S11 of a substantially
sinusoidal wave being approximately even. Namely, in the end
part 1d of the rotor 1 according to the first embodiment in
the axial direction, an abrupt change in the surface magnetic
10 flux density is inhibited in the circumferential direction R1.
This is because the second width W2 (see FIG. 2) of the rareearth magnet part 31 in the end part 20d of the ferrite bond
magnet 20 in the axial direction is narrower than the first
width W1 (see FIG. 2) of the rare-earth magnet part 31 in the
15 central part 20c of the ferrite bond magnet 20 in the axial
direction and the amount of use of the ferrite bond magnet 20
in the end part 20d in the axial direction is greater than the
amount of use of the ferrite bond magnet 20 in the central
part 20c in the axial direction.
20 [0057]
The distribution of the surface magnetic flux density in
the central part 1c of the rotor 1 according to the first
embodiment is represented by a waveform S12 of a substantially
sinusoidal wave. In the central part 1c of the rotor 1 in the
25 axial direction, while magnetic flux density equivalent to
that in the rotor 101a according to the first comparative
example is obtained in a magnetic pole central part (a north
pole or a south pole), magnetic flux density slightly less
than that in the rotor 101a according to the first comparative
30 example is obtained in an inter-pole part (between the north
pole and the south pole). This is because the first width W1
is wider than the second width W2 in the rare-earth magnet
part 31 shown in FIG. 2 and the amount of use of the ferrite
bond magnet 20 in the central part 20c in the axial direction

22
is less than the amount of use of the ferrite bond magnet 20
in the end part 20d. However, the decrease in the magnetic
flux density in the inter-pole part in the central part 1c can
be compensated for since the rotor 1 according to the first
5 embodiment includes a plurality of rare-earth magnet parts 31.
Accordingly, the rotor 1 according to the first embodiment is
capable of achieving inductive voltage equivalent to that of
the rotor 101a according to the first comparative example.
[0058]
10 (Effects of First Embodiment)
As described above, according to the first embodiment,
the rare-earth bond magnet 30 includes a plurality of rareearth magnet parts 31 arranged at intervals in the
circumferential direction R1. The rare-earth bond magnet 30 is
15 more expensive than the ferrite bond magnet 20. In the rotor 1
according to the first embodiment, since the rare-earth bond
magnet 30 includes a plurality of rare-earth magnet parts 31
arranged at intervals in the circumferential direction R1, the
amount of use of the rare-earth bond magnet 30 is reduced, and
20 thus the manufacturing cost of the rotor 1 can be reduced.
[0059]
Further, according to the first embodiment, the first
width W1 as the width in the circumferential direction of each
of the plurality of rare-earth magnet parts 31 in the central
25 part 20c of the ferrite bond magnet 20 in the axial direction
is wider than the second width W2 as the width in the
circumferential direction of each rare-earth magnet part 31 in
the end part 20d of the ferrite bond magnet 20 in the axial
direction. With this configuration, the magnetic pole of the
30 rare-earth magnet part 31 at the central part 20c of the
ferrite bond magnet 20 facing the stator core 91 in the radial
direction is made stronger than the magnetic pole of the rareearth magnet part 31 at the end part 20d of the ferrite bond
magnet 20 in the axial direction. Therefore, a sufficient

23
magnetic flux amount of the magnetic flux flowing from the
rotor 1 to the stator 9 can be secured while reducing the
manufacturing cost of the rotor 1.
[0060]
5 Here, when the length L1 in the axial direction of the
rotor 1 is longer than the length L9 in the axial direction of
the stator core 91 as shown in FIG. 2, the magnetic flux
amount of the interlinkage magnetic flux flowing from the
permanent magnets (i.e., the ferrite bond magnet 20 and the
10 rare-earth bond magnet 30) of the rotor 1 to the coil 92 of
the stator 9 can be increased. On the other hand, there is a
case where part of magnetic flux flowing from the end part 1d
of the rotor 1, not facing the stator core 91 in the radial
direction, toward the coil 92 turns into leakage flux. In such
15 a case, a sufficient magnetic flux amount of the magnetic flux
flowing from the rotor 1 to the stator 9 cannot be secured. In
the first embodiment, the first width W1 of the rare-earth
magnet part 31 is wider than the second width W2. With this
configuration, the magnetic pole of the rare-earth magnet part
20 31 at the central part 20c of the ferrite bond magnet 20 in
the axial direction is made stronger than the magnetic pole of
the rare-earth magnet part 31 at the end part 20d of the
ferrite bond magnet 20 in the axial direction. Accordingly, a
sufficient magnetic flux amount of the magnetic flux flowing
25 from the rotor 1 to the stator 9 can be secured.
[0061]
Furthermore, according to the first embodiment, since
the rare-earth bond magnet 30 includes a plurality of rareearth magnet parts 31 arranged at intervals in the
30 circumferential direction R1, an abrupt change in the surface
magnetic flux density of the rotor 1 is inhibited, and thus
the rotor 1 is capable of achieving inductive voltage
equivalent to that of the rotor 101a according to the first
comparative example. Thus, the rotor 1 according to the first

24
embodiment is capable of achieving accuracy of rotation
control equivalent to that of the rotor 101a according to the
first comparative example.
[0062]
5 Moreover, according to the first embodiment, the ferrite
bond magnet 20 supported by the shaft 10 has the polar
anisotropy. With this configuration, it is unnecessary to
dispose a rotor core that forms a magnetic path on the inner
side of the ferrite bond magnet 20 in the radial direction,
10 and thus the number of components in the rotor 1 can be
reduced and the weight of the rotor 1 can be reduced.
[0063]
In addition, according to the first embodiment, the
ferrite bond magnet 20 includes the first ferrite magnet part
15 41 and the second ferrite magnet part 42 aligned in the axial
direction. In order to mold the ferrite bond magnet 20
including the groove parts 21 each having a shape
corresponding to the shape of the rare-earth magnet part 31,
namely, in order to mold the groove parts 21 in each of which
20 the width W21 in the circumferential direction R1 in the
central part 20c in the axial direction is wider than the
width 22 in the circumferential direction R1 in the end part
20d in the axial direction, the mold needs to have a
complicated structure. Thus, the facility for molding the
25 ferrite bond magnet 20 gets expensive. In the first
embodiment, the ferrite bond magnet 20 includes the first
ferrite magnet part 41 and the second ferrite magnet part 42
divided from each other in the central part 20c in the axial
direction. Accordingly, it is not necessary to use the mold
30 for integrally molding the groove parts 21, and thus
productivity of the ferrite bond magnet 20 can be increased.
[0064]
(Second Embodiment)
FIG. 13 is a side view showing the configuration of a

25
rotor 2 according to a second embodiment. In FIG. 13,
components identical or corresponding to components shown in
FIG. 2 are assigned the same reference characters as in FIG.
2. The rotor 2 according to the second embodiment differs from
5 the rotor 1 according to the first embodiment in the shape of
a rare-earth magnet part 231. In other respects, the rotor 2
according to the second embodiment is the same as the rotor 1
according to the first embodiment. Thus, FIG. 2 is referred to
in the following description. Incidentally, the shaft 10 (see
10 FIG. 2) is not shown in FIG. 13.
[0065]
As shown in FIG. 13, the rotor 2 includes the ferrite
bond magnet 20 and a rare-earth bond magnet 230. The rareearth bond magnet 230 includes a plurality of rare-earth
15 magnet parts 231 arranged at intervals in the circumferential
direction R1.
[0066]
The first width W1 as a width in the circumferential
direction R1 of each rare-earth magnet part 231 in the central
20 part 20c of the ferrite bond magnet 20 in the axial direction
is wider than the second width W2 as a width in the
circumferential direction R1 of each rare-earth magnet part
231 in the end part 20d of the ferrite bond magnet 20 in the
axial direction. With this configuration, the magnetic pole of
25 the rare-earth magnet part 231 at the central part 20c of the
ferrite bond magnet 20 is made stronger than the magnetic pole
of the rare-earth magnet part 231 at the end part 20d of the
ferrite bond magnet 20. Thus, a sufficient magnetic flux
amount of the magnetic flux flowing from the rotor 2 to the
30 stator 9 can be secured.
[0067]
The rare-earth magnet part 231 includes a first part
231a and a plurality of second parts 231b and 231c connected
to the first part 231a at positions on the outer side of the

26
first part 231a in the axial direction. The first part 231a is
a wider part having the first width W1 in the rare-earth
magnet part 231. In the second embodiment, the width of the
first part 231a in the circumferential direction is constant
5 in the axial direction. Namely, in the second embodiment, the
width of the first part 231a in the circumferential direction
R1 (i.e., the first width W1) is constant in the axial
direction.
[0068]
10 The width of each of the plurality of second parts 231b
and 231c in the circumferential direction R1 gradually
increases toward the first part 231a. Namely, as the rotor 2
is viewed in the radial direction, the shape of the second
part 231b is a trapezoidal shape. Incidentally, the width of
15 the second part 231b in the circumferential direction R1 may
also be constant in the axial direction. Further, the rareearth magnet part 231 may also be configured to include only
one of the plurality of second parts 231b and 231c.
[0069]
20 The length L21 of the first part 231a in the axial
direction is longer than the length L22 of the second part
231b, 231c in the axial direction. With this configuration, in
the rare-earth magnet part 231, the magnetic pole of the rareearth magnet part 231 at the central part 20c of the ferrite
25 bond magnet 20 is made further stronger than the magnetic pole
of the rare-earth magnet part 231 at the end part 20d of the
ferrite bond magnet 20. Accordingly, it is made easier to
secure a sufficient magnetic flux amount of the magnetic flux
flowing from the rotor 2 to the stator 9.
30 [0070]
(Effects of Second Embodiment)
As described above, according to the second embodiment,
the rare-earth bond magnet 230 includes a plurality of rareearth magnet parts 231 arranged at intervals in the

27
circumferential direction R1. The rare-earth bond magnet 230
is more expensive than the ferrite bond magnet 20. In the
rotor 2 according to the second embodiment, since the rareearth bond magnet 230 includes a plurality of rare-earth
5 magnet parts 231 arranged at intervals in the circumferential
direction R1, the amount of use of the rare-earth bond magnet
230 is reduced, and thus the manufacturing cost of the rotor 2
can be reduced.
[0071]
10 Further, according to the second embodiment, the first
width W1 as the width in the circumferential direction of each
of the plurality of rare-earth magnet parts 231 in the central
part 20c of the ferrite bond magnet 20 in the axial direction
is wider than the second width W2 as the width in the
15 circumferential direction of each rare-earth magnet part 231
in the end part 20d of the ferrite bond magnet 20 in the axial
direction. With this configuration, the magnetic pole of the
rare-earth magnet part 31 at the central part 20c of the
ferrite bond magnet 20 facing the stator core 91 in the radial
20 direction is made stronger than the magnetic pole of the rareearth magnet part 31 at the end part 20d of the ferrite bond
magnet 20 in the axial direction. Therefore, a sufficient
magnetic flux amount of the magnetic flux flowing from the
rotor 2 to the stator 9 can be secured while reducing the
25 manufacturing cost of the rotor 2. Furthermore, a sufficient
magnetic flux amount of the magnetic flux flowing from the
rotor 2 to the stator 9 can be secured without forming an
overhang part 431f shown in FIGS. 15 and 16, which will be
described later, in the rare-earth magnet part 231.
30 [0072]
Moreover, according to the second embodiment, the rareearth magnet part 231 includes the first part 231a and the
second parts 231b and 231c connected to the first part 231a at
positions on the outer side of the first part 231a in the

28
axial direction. The first part 231a has the first width W1
which is constant in the axial direction. The length L21 of
the first part 231a in the axial direction is longer than the
length L22 of the second part 231b, 231c in the axial
5 direction. With this configuration, the magnetic pole of the
rare-earth magnet part 231 at the central part 20c of the
ferrite bond magnet 20 is made further stronger than the
magnetic pole of the rare-earth magnet part 231 at the end
part 20d of the ferrite bond magnet 20. Accordingly, it is
10 made easier to secure a sufficient magnetic flux amount of the
magnetic flux flowing from the rotor 2 to the stator 9.
[0073]
(Third Embodiment)
FIG. 14 is a plan view showing the configuration of a
15 rotor 3 according to a third embodiment. In FIG. 14,
components identical or corresponding to components shown in
FIG. 3 are assigned the same reference characters as in FIG.
3. The rotor 3 according to the third embodiment differs from
the rotor 1 according to the first embodiment in the shape of
20 a rare-earth magnet part 331. Incidentally, the shaft 10 and
the resin part 60 (see FIG. 3) are not shown in FIG. 14.
[0074]
As shown in FIG. 14, the rotor 3 includes the ferrite
bond magnet 20 and a rare-earth bond magnet 330. The rare25 earth bond magnet 330 includes a plurality of rare-earth
magnet parts 331 arranged at intervals in the circumferential
direction R1.
[0075]
In FIG. 14, a third width W3 represents the width in the
30 circumferential direction of an innermost part 331c of the
rare-earth magnet part 331 in the radial direction. A fourth
width W4 represents the width in the circumferential direction
of an outermost part 331d of the rare-earth magnet part 331 in
the radial direction. The third width W3 is wider than the

29
fourth width W4. Namely, the third width W3 and the fourth
width W4 satisfy the following expression (3):
W3 > W4 (3)
With this configuration, a joint area of the ferrite
5 bond magnet 20 and the rare-earth bond magnet 330 increases.
Accordingly, falling off of the rare-earth bond magnet 330
from the ferrite bond magnet 20 can be prevented even when
peeling occurs at the interface between the ferrite bond
magnet 20 and the rare-earth bond magnet 330 due to expansion
10 or contraction caused by a temperature change or centrifugal
force acting on the rotor 3.
[0076]
As above, in the second embodiment, the third width W3
is wider than the fourth width W4 in the rare-earth magnet
15 part 331, and thus each groove part 221 of the ferrite bond
magnet 20 in which the rare-earth magnet part 331 is disposed
is a dovetail groove.
[0077]
(Effects of Third Embodiment)
20 As described above, according to the third embodiment,
the third width W3 as the width in the circumferential
direction of the innermost part 331c of the rare-earth magnet
part 331 in the radial direction is wider than the fourth
width W4 as the width in the circumferential direction of the
25 outermost part 331d of the rare-earth magnet part 331 in the
radial direction. With this configuration, the joint area of
the ferrite bond magnet 20 and the rare-earth bond magnet 330
increases. Accordingly, the falling off of the rare-earth bond
magnet 330 from the ferrite bond magnet 20 can be prevented
30 even when peeling occurs at the interface between the ferrite
bond magnet 20 and the rare-earth bond magnet 330 due to
expansion or contraction caused by a temperature change or
centrifugal force acting on the rotor 3.
[0078]

30
(Fourth Embodiment)
FIG. 15 is a sectional view showing the configuration of
a rotor 4 according to a fourth embodiment. FIG. 16 is a
sectional view of the rotor 4 shown in FIG. 15 taken along the
5 line A16 - A16. The rotor 4 according to the fourth embodiment
differs from the rotor 1 according to the first embodiment in
the shapes of a ferrite bond magnet 420 and a rare-earth bond
magnet 430. In other respects, the rotor 4 according to the
fourth embodiment is the same as the rotor 1 according to the
10 first embodiment. Thus, FIG. 2 is referred to in the following
description. Incidentally, the shaft 10 is not shown in FIGS.
15 and 16.
[0079]
As shown in FIGS. 15 and 16, the rotor 4 includes the
15 ferrite bond magnet 420 and the rare-earth bond magnet 430.
[0080]
The ferrite bond magnet 420 includes a first ferrite
magnet part 441 and a second ferrite magnet part 442 aligned
in the axial direction. A step part 420f is formed in a
20 central part 420c of the ferrite bond magnet 420 in the axial
direction. The step part 420f is recessed from an outer
periphery 420a toward an inner circumference 420b of the
ferrite bond magnet 420. The step part 420f is formed by a
first step part 441f formed in the first ferrite magnet part
25 441 and a second step part 442f formed in the second ferrite
magnet part 442. The first step part 441f is formed at an end
face 441a of the first ferrite magnet part 441 in the axial
direction in contact with the second ferrite magnet part 442.
The second step part 442f is formed at an end face 442a of the
30 second ferrite magnet part 442 in the axial direction in
contact with the first ferrite magnet part 441.
[0081]
The rare-earth bond magnet 430 includes a plurality of
rare-earth magnet parts 431 arranged at intervals in the

31
circumferential direction R1. The rare-earth magnet part 431
includes an overhang part 431f formed in a central part 431c
in the axial direction facing the stator core 91 (see FIG. 2)
in the radial direction. The overhang part 431f extends inward
5 in the radial direction from the central part 431c of the
rare-earth magnet part 431 in the axial direction. With this
configuration, in the rare-earth magnet part 431, the magnetic
pole of the rare-earth magnet part 431 at the central part
420c of the ferrite bond magnet 420 is made further stronger
10 than the magnetic pole of the rare-earth magnet part 431 at
each end part 420d of the ferrite bond magnet 420.
Accordingly, the magnetic flux amount of the interlinkage
magnetic flux flowing from the rotor 4 to the coil 92 can be
increased further.
15 [0082]
The overhang part 431f and the step part 420f are joined
to each other. With this configuration, the joint area of the
ferrite bond magnet 20 and the rare-earth bond magnet 30
increases. Accordingly, the falling off of the rare-earth bond
20 magnet 430 from the ferrite bond magnet 420 can be prevented
even when peeling occurs at the interface between the ferrite
bond magnet 420 and the rare-earth bond magnet 430 due to
expansion or contraction caused by a temperature change or
centrifugal force acting on the rotor 4.
25 [0083]
(Effects of Fourth Embodiment)
As described above, according to the fourth embodiment,
the rare-earth magnet part 431 includes the overhang part 431f
formed in the central part 431c in the axial direction facing
30 the stator core 91 in the radial direction. With this
configuration, in the rare-earth magnet part 431, the magnetic
pole of the rare-earth magnet part 431 at the central part
420c of the ferrite bond magnet 420 is made further stronger
than the magnetic pole of the rare-earth magnet part 431 at

32
the end part 420d of the ferrite bond magnet 420. Accordingly,
the magnetic flux amount of the interlinkage magnetic flux
flowing from the rotor 4 to the coil 92 can be increased.
Namely, the magnetic flux amount of effective magnetic flux
5 necessary for the driving of the motor can be increased.
[0084]
Further, according to the fourth embodiment, the
overhang part 431f of the rare-earth magnet part 431 and the
step part 420f of the ferrite bond magnet 420 are joined to
10 each other. With this configuration, the joint area of the
ferrite bond magnet 20 and the rare-earth bond magnet 30
increases. Accordingly, the falling off of the rare-earth bond
magnet 430 from the ferrite bond magnet 420 can be prevented
even when peeling occurs at the interface between the ferrite
15 bond magnet 420 and the rare-earth bond magnet 430 due to
expansion or contraction caused by a temperature change or
centrifugal force acting on the rotor 4.
[0085]
(Fifth Embodiment)
20 FIG. 17 is a sectional view showing the configuration of
a rotor 5 according to a fifth embodiment. FIG. 18 is a
partial sectional view showing the configuration of the rotor
5 shown in FIG. 17. In FIGS. 17 and 18, the same reference
characters as in FIGS. 15 and 16 are assigned to components.
25 The rotor 5 according to the fifth embodiment differs from the
rotor 4 according to the fourth embodiment in the shape of an
overhang part 531f of a rare-earth magnet part 531.
Incidentally, the shaft 10 is not shown in FIGS. 17 and 18.
[0086]
30 As shown in FIG. 17, the rotor 5 includes the ferrite
bond magnet 420 and a rare-earth bond magnet 530. The rareearth bond magnet 530 includes a plurality of rare-earth
magnet parts 531 arranged at intervals in the circumferential
direction R1.

33
[0087]
As shown in FIG. 18, the rare-earth magnet part 531
includes the overhang part 531f formed in a central part 531c
in the axial direction facing the stator core 91 (see FIG. 2)
5 in the radial direction. The overhang part 531f extends inward
in the radial direction from the central part 531c of the
rare-earth magnet part 531 in the axial direction. The
overhang part 531f and the step part 420f of the ferrite bond
magnet 420 are joined to each other.
10 [0088]
A fifth width W5 as the width of the overhang part 531f
in the circumferential direction R1 is wider than the width A2
of the rare-earth magnet part 531 in the circumferential
direction R1. Here, the "width of the overhang part 531f in
15 the circumferential direction R1" is the length of a straight
line extending in the overhang part 531f in a direction
orthogonal to a straight line M connecting the axis C1 and the
overhang part 531f.
[0089]
20 As described above, according to the fifth embodiment,
the width W5 of the overhang part 531f of the rare-earth
magnet part 531 in the circumferential direction R1 is wider
than the first width W1 of the rare-earth magnet part 531.
With this configuration, the joint area of the overhang part
25 531f and the central part 420c of the ferrite bond magnet 420
in the axial direction increases, and thus the rare-earth bond
magnet 530 is further less likely to fall off from the ferrite
bond magnet 420.
[0090]
30 (Sixth Embodiment)
FIG. 19 is a partial sectional view showing the
configuration of a rotor 6 according to a sixth embodiment. In
FIG. 19, components identical or corresponding to components
shown in FIG. 15 or 16 are assigned the same reference

34
characters as in FIG. 15 or 16. The rotor 6 according to the
sixth embodiment differs from the rotor 4 according to the
fourth embodiment in the shapes of a ferrite bond magnet 620
and a rare-earth bond magnet 630.
5 [0091]
As shown in FIG. 19, the rotor 6 includes the ferrite
bond magnet 620 and the rare-earth bond magnet 630. The
ferrite bond magnet 620 includes a first ferrite magnet part
441 and a second ferrite magnet part 442 aligned in the axial
10 direction. The first ferrite magnet part 441 includes a first
concave part 641g formed at a bottom surface 441s of the first
step part 441f. The second ferrite magnet part 442 includes a
second concave part 642g formed at a bottom surface 442s of
the second step part 442f. Incidentally, the ferrite bond
15 magnet 620 may also be configured to include only one of the
first and second concave parts 641g and 642g. Further, the
ferrite bond magnet 620 may be configured to include a
plurality of first concave parts 641g or a plurality of second
concave parts 642g.
20 [0092]
The rare-earth bond magnet 630 includes rare-earth
magnet parts 631. The rare-earth magnet part 631 includes an
overhang part 631f. The overhang part 631f includes a first
convex part 631g that is fitted in the first concave part 641g
25 and a second convex part 631h that is fitted in the second
concave part 642g. With this configuration, the rare-earth
bond magnet 630 is further less likely to fall off from the
ferrite bond magnet 620. Since the overhang part 631f includes
the first convex part 631g and the second convex part 631h as
30 above, the length in the axial direction of an inner
circumferential side of the overhang part 631f where the first
convex part 631g and the second convex part 631h are formed is
longer than the length in the axial direction of an outer
circumferential side of the overhang part 631f.

35
[0093]
As described above, in the rotor 6 according to the
sixth embodiment, the first convex part 631g of the overhang
part 631f of the rare-earth magnet part 631 is fitted in the
5 first concave part 641g formed in the first step part 441f of
the ferrite bond magnet 620. With this configuration, the
rare-earth bond magnet 630 is further less likely to fall off
from the ferrite bond magnet 620.
[0094]
10 Further, in the rotor 6 according to the sixth
embodiment, the second convex part 631h of the overhang part
631f is fitted in the second concave part 642g formed in the
second step part 442f of the ferrite bond magnet 620. With
this configuration, the rare-earth bond magnet 630 is further
15 less likely to fall off from the ferrite bond magnet 620.
[0095]
(Seventh Embodiment)
FIG. 20 is a sectional view showing the configuration of
a rotor 7 according to a seventh embodiment. In FIG. 20,
20 components identical or corresponding to components shown in
FIGS. 1 to 3 are assigned the same reference characters as in
FIGS. 1 to 3. The rotor 7 according to the seventh embodiment
differs from the rotor 1 according to the first embodiment in
the configuration of a rare-earth bond magnet 730.
25 [0096]
As shown in FIG. 20, the rotor 7 includes the ferrite
bond magnet 20 and the rare-earth bond magnet 730.
[0097]
The rare-earth bond magnet 730 includes a plurality of
30 rare-earth magnet parts 731 arranged at intervals in the
circumferential direction R1 and a connection part 732
connecting rare-earth magnet parts 731 adjoining in the
circumferential direction R1 among the plurality of rare-earth
magnet parts 731. The rare-earth magnet part 31 includes an

36
overhang part 731f formed in a central part 731c in the axial
direction. The overhang part 731f and a concave part 20f
formed in the central part of the ferrite bond magnet 20 in
the axial direction are joined to each other. In FIG. 20, the
5 concave part 20f is a groove part in a ring shape about the
axis C1.
[0098]
The connection part 732 connects the overhang parts 731f
of rare-earth magnet parts 731 adjoining in the
10 circumferential direction R1. This increases rigidity of the
rare-earth bond magnet 730, and thus the rare-earth bond
magnet 730 is further less likely to fall off from the ferrite
bond magnet 20. The connection part 732 and the concave part
20f of the ferrite bond magnet 20 are joined to each other.
15 [0099]
As described above, according to the seventh embodiment,
the rare-earth bond magnet 730 includes the connection part
732 connecting rare-earth magnet parts 731 adjoining in the
circumferential direction R1 among the plurality of rare-earth
20 magnet parts 731 arranged at intervals in the circumferential
direction R1. With this configuration, the rigidity of the
rare-earth bond magnet 730 increases, and thus the rare-earth
bond magnet 730 is further less likely to fall off from the
ferrite bond magnet 20.
25 [0100]
(Eighth Embodiment)
FIG. 21 is a side view showing the configuration of a
rotor 8 according to an eighth embodiment. FIG. 22 is a plan
view showing the configuration of the rotor 8 according to the
30 eighth embodiment. FIG. 23 is a sectional view of the rotor 8
shown in FIG. 21 taken along the line A23 - A23. In FIGS. 21
to 23, components identical or corresponding to components
shown in FIGS. 1 to 3 are assigned the same reference
characters as in FIGS. 1 to 3. The rotor 8 according to the

37
eighth embodiment differs from the rotor according to any one
of the first to seventh embodiments in further including ring
members 81 and 82. Incidentally, the shaft 10 and the resin
part 60 (see FIG. 3) are not shown in FIGS. 21 to 23.
5 [0101]
As shown in FIGS. 21 to 23, the rotor 8 includes the
ferrite bond magnet 20, the rare-earth bond magnet 30 and a
plurality of ring members 81 and 82.
[0102]
10 Each of the ring members 81 and 82 is a member having a
ring shape about at the axis C1. The ring members 81 and 82
are formed of a resin such as unsaturated polyester resin, for
example.
[0103]
15 The ring member 81 is situated on the +z-axis side
relative to the ferrite bond magnet 20 and the rare-earth bond
magnet 30. The ring member 81 is fixed to an end face 20j of
the ferrite bond magnet 20 facing the +z-axis direction and
end faces 31j of the rare-earth magnet parts 31 facing the +z20 axis direction.
[0104]
The ring member 82 is situated on the -z-axis side
relative to the ferrite bond magnet 20 and the rare-earth bond
magnet 30. The ring member 82 is fixed to an end face 20k of
25 the ferrite bond magnet 20 facing the -z-axis direction and
end faces 31k of the rare-earth magnet parts 31 facing the -zaxis direction. Incidentally, the rotor 8 may also be
configured to include only one of the plurality of ring
members 81 and 82.
30 [0105]
(Effects of Eighth Embodiment)
As described above, according to the eighth embodiment,
the rotor 8 includes the ring member 81 fixed to the end face
20j of the ferrite bond magnet 20 facing the +z-axis direction

38
and the end faces 31j of the rare-earth magnet parts 31 facing
the +z-axis direction. With this configuration, the rare-earth
magnet parts 31 are connected to the ferrite bond magnet 20
via the ring member 81, and thus the rare-earth magnet parts
5 31 are less likely to fall off from the ferrite bond magnet
20.
[0106]
Further, the rotor 8 according to the eighth embodiment
includes the ring member 82 fixed to the end face 20k of the
10 ferrite bond magnet 20 facing the -z-axis direction and the
end faces 31k of the rare-earth magnet parts 31 facing the -zaxis direction. With this configuration, the rare-earth magnet
parts 31 are connected to the ferrite bond magnet 20 via the
plurality of ring members 81 and 82, and thus the rare-earth
15 magnet parts 31 are less likely to fall off from the ferrite
bond magnet 20.
[0107]
(First Modification of Eighth Embodiment)
FIG. 24 is a plan view showing the configuration of a
20 rotor 8A according to a first modification of the eighth
embodiment. FIG. 22 is a sectional view of the rotor 8A shown
in FIG. 25 taken along the line A25 - A25. The rotor 8A
according to the first modification of the eighth embodiment
differs from the rotor 8 according to the eighth embodiment in
25 that ring members 81A and 82A are connected to a resin part
60A.
[0108]
As shown in FIGS. 24 and 25, the rotor 8A includes the
shaft 10, the ferrite bond magnet 20, the rare-earth bond
30 magnet 30, the ring members 81A and 82A as a first resin part,
and the resin part 60A as a second resin part.
[0109]
The resin part 60A includes the inner cylinder part 61
supported by the shaft 10, an outer cylinder part 62A fixed to

39
the inner circumference 20b of the ferrite bond magnet 20, and
a plurality of ribs 63A connecting the inner cylinder part 61
and the outer cylinder part 62A.
[0110]
5 The ring members 81A and 82A are connected to the resin
part 60A (specifically, the outer cylinder part 62A and the
ribs 63A). In the first modification of the eighth embodiment,
the ring members 81A and 82A are connected to the outer
cylinder part 62A of the resin part 60A by means of integral
10 molding. Namely, in the first modification of the eighth
embodiment, the shaft 10, the ferrite bond magnet 20 and the
rare-earth bond magnet 30 are connected together via the resin
part 60A and the ring members 81A and 82A.
[0111]
15 As described above, according to the first modification
of the eighth embodiment, in the rotor 8A, the ring members
81A and 82A are connected to the resin part 60A. With this
configuration, when the shaft 10 and the ferrite bond magnet
20 are integrally molded via the resin part 60A made of a
20 resin, the ring members 81A and 82A can also be molded at the
same time, and thus manufacturing steps of the rotor 8A can be
reduced.
[0112]
Here, the natural frequency of the rotor 8A changes
25 depending on the rigidity of the rotor 8A. The rigidity of the
rotor 8A can be adjusted by changing the width in the
circumferential direction R1 and the length in the radial
direction of the rib 63A and the number of ribs 63A in the
resin part 60A, for example. In the first modification of the
30 eighth embodiment, the length in the radial direction of each
rib 63A is increased since the ribs 63A are connected to the
ring members 81A and 82A. Accordingly, the rigidity of the
rotor 8A can be changed. Namely, the natural frequency of the
rotor 8A can be changed. Thus, the occurrence of resonance can

40
be inhibited and vibrational characteristics of the rotor 8A
can be adjusted.
[0113]
Further, the inertia moment of the rotor 8A changes
5 depending on the mass of the rotor 8A. The mass of the rotor
8A can be adjusted by changing the width in the
circumferential direction R1 and the length in the radial
direction of the rib 63A and the number of ribs 63A. With the
increase in the inertia moment, the rotation of the rotor 8A
10 can be more stabilized although higher starting torque is
needed. In the first modification of the eighth embodiment,
the length in the radial direction of each rib 63A is
increased since the ribs 63A are connected to the ring members
81 and 82 as described above. With this configuration, the
15 inertia moment of the rotor 8A can be increased. As above, in
the first modification of the eighth embodiment, the natural
frequency and the inertia moment of the rotor 8A can be
adjusted since the ring members 81A and 82A are connected to
the resin part 60A.
20 [0114]
(Ninth Embodiment)
FIG. 26 is a diagram schematically showing the
configuration of an air conditioner 900 according to a ninth
embodiment. As shown in FIG. 26, the air conditioner 900
25 includes an indoor unit 910 and an outdoor unit 920 connected
to the indoor unit 910 via a refrigerant pipe 930. The air
conditioner 900 is capable of executing an operation such as a
cooling operation of blowing out cool air from the indoor unit
910 or a heating operation of blowing out warm air from the
30 indoor unit 910, for example.
[0115]
The indoor unit 910 includes an indoor blower 911 as a
blower and a housing 912 that covers the indoor blower 911.
The indoor blower 911 includes the motor 100 and an impeller

41
911a fixed to the shaft 10 of the motor 100. The impeller 911a
is driven by the motor 100 to generate an airflow. The
impeller 911a is a cross-flow fan, for example.
[0116]
5 The outdoor unit 920 includes an outdoor blower 921 as a
blower, a compressor 922, and a housing 923 that covers the
outdoor blower 921 and the compressor 922. The outdoor blower
921 includes the motor 100 and an impeller 921a fixed to the
shaft 10 (see FIG. 1) of the motor 100. The impeller 921a is
10 driven by the motor 100 to generate an airflow. The impeller
921a is a propeller fan, for example. The compressor 922
includes a motor 922a and a compression mechanism part 922b
driven by the motor 922a.
[0117]
15 As described above, in the air conditioner 900 according
to the ninth embodiment, the motor 100 according to the first
embodiment is applied to the indoor blower 911 and the outdoor
blower 921. In the motor 100 according to the first
embodiment, the interlinkage magnetic flux flowing from the
20 rotor 1 to the coil 92 (see FIGS. 1 and 2) can be increased,
and thus reliability of the motor 100 increases. Accordingly,
reliability of the indoor blower 911 and the outdoor blower
921 including the motor 100 also increases. Further,
reliability of the air conditioner 900 including the indoor
25 blower 911 and the outdoor blower 921 also increases.
[0118]
Incidentally, the motor 100 may also be provided in only
one of the indoor blower 911 and the outdoor blower 921.
Further, the motor 100 may also be applied to the motor 922a
30 of the compressor 922. Furthermore, the motor 100 according to
the ninth embodiment may be installed not only in the air
conditioner 900 but also in equipment of a different type.

42
DESCRIPTION OF REFERENCE CHARACTERS
[0119]
1, 2, 3, 4, 5, 6, 7, 8, 8A: rotor, 9: stator, 10:
shaft, 20, 420, 620: ferrite bond magnet, 20a, 420a: outer
5 periphery, 20c, 420c: central part, 20d: end part, 30, 230,
330, 430, 530, 630, 730: rare-earth bond magnet, 31, 231, 331,
431, 531, 631, 731: rare-earth magnet part, 41, 441: first
ferrite magnet part, 42, 442: second ferrite magnet part, 60,
60A: resin part, 81, 81A, 82, 82A: ring member, 91: stator
10 core, 100: motor, 231a: first part, 231b: second part, 420f:
step part, 431f, 531f, 731f: overhang part, 441s, 442s:
bottom surface, 631g: first convex part, 631h: second convex
part, 641g: first concave part, 642g: second concave part,
732: connection part, 900: air conditioner, 910: indoor unit,
15 911: indoor blower, 911a, 921a: impeller, 920: outdoor unit,
921: outdoor blower, C1: axis line, L1, L9, L21, L22: length
in axial direction, W1: first width, W2: second width, W3:
third width, W4: fourth width, W5: fifth width.

We Claim:
1. A rotor comprising:
a rotary shaft;
5 a first permanent magnet supported by the rotary shaft;
and
a second permanent magnet supported by an outer
periphery of the first permanent magnet and having a magnetic
pole stronger than a magnetic pole of the first permanent
10 magnet,
wherein the second permanent magnet comprises a
plurality of magnet parts arranged at intervals in a
circumferential direction of the first permanent magnet, and
wherein a first width as a width in the circumferential
15 direction of each of the plurality of magnet parts at a
central part of the first permanent magnet in an axial
direction of the rotary shaft is wider than a second width as
a width in the circumferential direction of each of the magnet
parts at an end part of the first permanent magnet in the
20 axial direction.
2. The rotor according to claim 1, wherein a width of the
magnet part in the circumferential direction gradually
increases from the end part toward the central part of the
25 first permanent magnet in the axial direction.
3. The rotor according to claim 1 or 2, wherein the magnet
part comprises:
a first part; and
30 a second part that is connected to the first part at a
position on an outer side of the first part in the axial
direction,
wherein a width of the second part in the
circumferential direction gradually increases toward the first

44
part.
4. The rotor according to claim 3, wherein a width of the
first part in the circumferential direction is constant in the
5 axial direction.
5. The rotor according to claim 3 or 4, wherein a length of
the first part in the axial direction is longer than a length
of the second part in the axial direction.
10
6. The rotor according to any one of claims 1 to 5, wherein
the first permanent magnet comprises a first split magnet part
and a second split magnet part arranged in the axial
direction.
15
7. The rotor according to any one of claims 1 to 6, wherein
a third width as a width in the circumferential direction of
an innermost part of the magnet part in a radial direction of
the second permanent magnet is greater than a fourth width as
20 a width in the circumferential direction of an outermost part
of the magnet part in the radial direction.
8. The rotor according to any one of claims 1 to 7, wherein
the first permanent magnet has a step part formed in the
25 central part in the axial direction, and
wherein the magnet part has an overhang part that is
fitted in the step part.
9. The rotor according to claim 8, wherein a fifth width as
30 a width of the overhang part in the circumferential direction
is wider than the first width.
10. The rotor according to claim 8 or 9, wherein the first
permanent magnet has a concave part formed at a bottom surface

45
of the step part, and
wherein the overhang part has a convex part that is
fitted in the concave part.
5 11. The rotor according to any one of claims 1 to 10,
wherein the second permanent magnet has a connection part that
connects the magnet parts adjoining in the circumferential
direction among the plurality of magnet parts.
10 12. The rotor according to any one of claims 1 to 11,
further comprising a first resin part that is fixed to the
first permanent magnet and the second permanent magnet in the
axial direction.
15 13. The rotor according to claim 12, further comprising a
second resin part that connects the rotary shaft and the first
permanent magnet,
wherein the first resin part is connected to the second
resin part.
20
14. The rotor according to any one of claims 1 to 13,
wherein the first permanent magnet is a ferrite bond magnet,
and
wherein the second permanent magnet is a rare-earth bond
25 magnet.
15. The rotor according to any one of claims 1 to 14,
wherein the rotor has 2n magnetic poles (n: natural number
greater than or equal to 1), and
30 wherein the first permanent magnet and the second
permanent magnet have polar anisotropy.
16. A motor comprising:
the rotor according to any one of claims 1 to 15; and

46
a stator.
17. The motor according to claim 16, wherein the stator
comprises a stator core, and
5 wherein a length of the rotor in the axial direction is
longer than a length of the stator core in the axial
direction.
18. A blower comprising:
10 the motor according to claim 16 or 17; and
an impeller that is driven by the motor.
19. An air conditioner comprising:
an indoor unit; and
15 an outdoor unit that is connected to the indoor unit,
wherein at least one of the indoor unit and the outdoor
unit comprises the motor according to claim 16 or 17.