Technical Field
5 [0001] The present invention relates to an innerrotor
permanent magnet electric motor including a rotor
disposed coaxially with a cylindrical stator on the
inner diameter side of the stator.
Background Art
10 [0002] As an electric motor, an inner-rotor
permanent magnet electric motor has been conventionally
known, in which a columnar rotor including a permanent
magnet portion is disposed coaxially with a cylindrical
stator, which generates a rotating magnetic field, on
15 the inner diameter side of the cylindrical stator.
[0003] This type of permanent magnet electric motor
includes a permanent magnet electric motor including: a
rotor including an annular permanent magnet portion
facing a stator in a radial direction; and a coupling
20 portion (yoke) that couples the permanent magnet
portion to a shaft. In the permanent magnet electric
motor of Patent Literature 1, a bearing house portion
(bearing bracket) that holds a bearing is disposed
close to the rotor in the axis direction of the stator,
25 so that the electric motor is downsized in the axis
direction.
3
Citation List
Patent Literature
[0004] Patent Literature 1: Japanese Patent
Application Laid-open No. 2011-109861
5 Disclosure of Invention
Technical Problem
[0005] However, there has been a problem that, if
the bearing house portion (bearing bracket) formed of a
magnetic substance is disposed close to the permanent
10 magnet portion of the rotor, the magnetic flux flowing
from the permanent magnet portion of the rotor to the
yoke (coupling portion) side of the stator also flows
to the bearing house portion side, and a leakage flux
increases, so that the output of the permanent magnet
15 electric motor is lowered.
Advantageous Effects of Invention
[0006] In this regard, it is an object of the
present invention to provide a permanent magnet
electric motor that can be downsized in an axis
20 direction and can suppress a leakage flux.
Solution to Problem
[0007] According to an aspect of the present
invention, there is provided a permanent magnet
electric motor including: a columnar rotor including a
25 permanent magnet portion annularly disposed; a shaft
disposed along a rotation axis of the rotor; a
4
cylindrical stator core disposed on an outer
circumferential side of the rotor; a main body
including a shell integrally formed with the stator
core; a bracket attached to one end side of the main
5 body; and a bearing that rotatably supports the shaft.
The bracket includes a bearing house portion that
stores the bearing, and a non-magnetic portion that is
connected to the bearing house portion.
The bearing house portion is disposed on an inner
10 diameter side relative to the permanent magnet portion
as viewed from an axis direction of the rotation axis.
An edge portion of the bearing house portion on an
outer diameter side is covered with the non-magnetic
portion.
15 [0008] According to the present invention, it is
possible to downsize an electric motor in an axis
direction of a rotation axis and to suppress a leakage
flux flowing from a permanent magnet portion of a rotor
to a bearing house portion side.
20 Brief Description of Drawings
[0009] [Fig. 1] Fig. 1 is an overall perspective
view of a permanent magnet electric motor according to
the present invention.
[Fig. 2] Fig. 2 is a transverse cross-sectional view
25 of the permanent magnet electric motor according to the
present invention.
5
[Fig. 3] Fig. 3 is a perspective view of a bracket of
the permanent magnet electric motor according to the
present invention.
[Fig. 4] Fig. 4 is an overall perspective view of the
5 permanent magnet electric motor according to the
present invention, showing a state in which the bracket
of Fig. 3 is removed.
[Fig. 5] Fig. 5 is a cross-sectional view of a crosssection
taken along a slitted groove shown in Fig. 1.
10 Mode(s) for Carrying Out the Invention
[0010] Next, an embodiment of the present invention
will be described with reference to the drawings. In
the following description about the drawings, the same
or similar portions will be denoted by the same or
15 similar reference symbols. It should be noted that the
drawings are schematic and may differ from reality.
Therefore, specific constituent parts should be
determined by referring to the following description.
[0011] Further, the embodiment to be described below
20 exemplifies apparatuses and methods for embodying the
technical idea of the present invention, and the
technical idea of the present invention does not
specify the shape, structure, arrangement, and the like
of the constituent parts to those described below.
25 Various modifications can be made to the technical idea
of the present invention within the technical scope
6
defined by the claims.
[0012] Hereinafter, an electric motor according to
an embodiment of the present invention will be
described.
5 [0013]
Figs. 1 to 5 are views for describing a
configuration of a permanent magnet electric motor 1 of
this embodiment. As shown in those figures, the
permanent magnet electric motor 1 is a brushless DC
10 motor, for example. The permanent magnet electric motor
1 is, for example, used to rotationally drive a blower
fan mounted in an outdoor unit of an air conditioner,
though not shown in the figures.
[0014] As shown in Figs. 1 and 2, the permanent
15 magnet electric motor 1 of this embodiment includes a
stator 2, a rotor 3, a motor shell (casing, main body)
10, and a bracket 41.
Hereinafter, an inner-rotor permanent magnet
electric motor 1 will be described as an example, in
20 which a columnar rotor 3 including a permanent magnet
portion 31 is rotatably disposed inward in the radial
direction of a cylindrical stator 2 that generates a
rotating magnetic field.
[0015]
25 As shown in Fig. 2, the rotor 3 includes an
annular permanent magnet portion 31 and a coupling
7
portion 35, which is disposed on the inner diameter
side relative to the permanent magnet portion 31 and
couples the permanent magnet portion 31 and a shaft 32
to each other. The shaft 32 is fixed to the columnar
5 rotor 3 along the center axis of the rotor 3. In this
embodiment, the permanent magnet portion 31 and the
coupling portion 35 of the rotor 3 are formed by
integral molding of a resin material in which a ferrite
magnetic substance is mixed. After the molding, only
10 the permanent magnet portion 31 is magnetized to cause
the permanent magnet portion 31 to function as a
ferrite bonded magnet. Further, the permanent magnet
portion 31 is magnetized to be a polar anisotropic
magnet in which a south pole and a north pole
15 alternately appear in the circumferential direction
thereof. Thus, a part of a yoke for concentrating the
flow of the magnetic flux of the permanent magnet
portion 31 becomes unnecessary, and the leakage flux
can be suppressed.
20 Note that the permanent magnet portion 31 and the
coupling portion 35 may be formed separately. For
example, the rotor 3 may be a so-called surface magnet
(SPM) rotor, in which a plurality of ferrite sintered
magnets (corresponding to the permanent magnet portion
25 31), which are obtained by sintering a powder-like
ferrite magnetic substance in a mold, are annularly
8
attached to the outer circumferential surface of a
rotor core (corresponding to the coupling portion 35).
[0016] The stator 2 includes a stator core 21
including a cylindrical yoke portion (not shown) and a
5 plurality of teeth portions (not shown) extending from
the yoke portion to the inner diameter side, and
winding (not shown) wound around the teeth portion via
an insulator. The stator 2 is covered with the motor
shell 10 (main body) formed of resin by resin integral
10 molding, except for the inner circumferential surface
of the stator core 21 (see Figs. 2 and 4). Specifically,
the motor shell 10 covers the stator 2 including the
stator core 21 and the winding. As shown in Figs. 1 and
2, the stator 2 is disposed on the outer
15 circumferential side of the rotor 3 (outward in the
radial direction of the permanent magnet electric motor
1). Further, the stator core 21 of the stator 2 is
disposed such that the teeth portion of the stator core
21 faces the permanent magnet portion 31 of the rotor 3
20 in the radial direction. In other words, the stator 2
is disposed such that the annular permanent magnet
portion 31 of the rotor 3 faces the stator core 21 of
the stator 2 in the radial direction.
[0017] The motor shell 10 may have any shape. For
25 example, the motor shell 10 may be formed into a hollow
cylindrical shape having an open end surface on one
9
side (in the embodiment, the opposite output side of
the shaft 32) in the axis direction of the center axis
of the permanent magnet electric motor 1, that is, the
rotation axis of the rotor 3 (hereinafter, rotation
5 axis C). In this embodiment, the motor shell 10
includes an annular portion 12 and an end surface
portion 13 formed at the end portion of the annular
portion 12 on the opposite side of the opening.
[0018] The rotor 3 is rotatably disposed on the
10 inner circumferential side of the stator core 21 of the
stator 2 with a predetermined clearance (gap) from the
stator core 21. As shown in Figs. 2, 4, and 5, the
permanent magnet portion 31 formed in an annular shape
is disposed on the outer side (outer circumference
15 side) in the radial direction of the rotor 3 so as to
face the stator core 21.
[0019] The rotor 3 is fixed to the circumference of
the shaft 32. The shaft 32 is rotatably supported
(held) by a first bearing 33 and a second bearing 34
20 fixed to the outer circumferential surface of the shaft
32. Further, the first bearing 33 is stored (held) in a
first bearing storing portion 42 (bearing house
portion) to be described later, and the second bearing
34 is stored (held) in a second bearing storing portion
25 43 to be described later, so that the rotor 3 is
rotatably supported. The first bearing storing portion
10
42 and the second bearing storing portion 43 are formed
of, for example, a magnetic substance of chromiumnickel-
based stainless steel.
[0020]
5 As shown in Figs. 2, 3, and 5, the first bearing
33 is fixed to one end side (opposite output side) of
the shaft 32 at the inner race side of the first
bearing 33. The second bearing 34 is fixed to the other
end side (output side) of the shaft 32 at the inner
10 race side of the second bearing 34. The first bearing
33 and the second bearing 34 (a pair of bearings)
cooperate to rotatably support the shaft 32 and the
rotor 3 fixed to the shaft 32. For example, a ball
bearing is used for each of the first bearing 33 and
15 the second bearing 34.
[0021] The bracket 41 includes the first bearing
storing portion 42 that is formed of a magnetic
substance and stores the first bearing 32, and a nonmagnetic
portion 44 (end surface portion) formed of a
20 non-magnetic substance (e.g., resin). In the motor
shell 10 (main body) of the permanent magnet electric
motor 1, the bracket 41 is disposed at an end in the
center axis C direction, that is, disposed on the
opposite output side of the shaft 32. The non-magnetic
25 portion 44 of the bracket 41 includes a connection
portion 45 connected to the first bearing storing
11
portion 42 (see Figs. 2, 3, and 5). The non-magnetic
portion 44 of the bracket 41 is integrally formed with
the first bearing storing portion 42, which is a
magnetic portion, by insert molding. The non-magnetic
5 portion 44 is connected to the first bearing storing
portion 42 (bearing house portion) at the connection
portion 45. The bracket 41 is attached to the end
portion of the motor shell 10 (main body) on the
opposite output side by using screws to serve as a lid
10 for covering the opening of the motor shell 10 (main
body). Note that the opening of the motor shell 10 may
be provided toward the output side. In this case, the
bracket 41 is disposed not on the opposite output side
of the shaft 32 but on the output side of the shaft 32.
15 [0022] The non-magnetic portion 44 (end surface
portion) of the bracket 41 is formed into a
substantially circular plate shape having the outer
shape in the radial direction, which expands to the
outer circumferential surface of the motor shell 10 in
20 the radial direction. The non-magnetic portion 44 of
the bracket 41 forms a resin shell of the permanent
magnet electric motor 1 together with the motor shell
10. Additionally, the non-magnetic portion 44 includes
protrusions 410, which protrude outward in the radial
25 direction relative to the outer circumferential surface
of the motor shell 10, as viewed from the rotation axis
12
C direction. The protrusions 410 each abut on the basal
end portion of a guard portion 102 of the motor shell
10. The guard portion 102 will be described later.
The protrusions 410 of the bracket 41 are formed
5 as many as the guard portions 102 provided to the motor
shell 10 (three positions). For example, the
protrusions 410 are each formed into a trapezoid as
viewed from the rotation axis C direction and each
include, at the center portion thereof, a screw through
10 hole 413 penetrating in the rotation axis C direction.
[0023] Note that the bracket 41 includes a slitted
groove 416 for providing an electrically conductive
member 5 for measures against electrolytic corrosion,
which will be described later, in the outer surface
15 exposed to the outside in the permanent magnet electric
motor 1 after assembling (see Figs. 1 and 3).
The slitted groove 416 extends outward in the
radial direction from the center portion of the bracket
41 (tubular connection portion 45 of the non-magnetic
20 portion 44 to be described later) to the outer
circumferential surface of the bracket 41, and further
extends in the axis direction from there to the
position abutting on the motor shell 10.
[0024] The bracket 41 is fitted into the motor shell
25 10 (main body) and then screwed at screw holes 103 (to
be described later) of the guard portions 102 of the
13
motor shell 10 via the screw through holes 413 (see Fig.
1).
Further, the first bearing storing portion
(bearing house portion) 42 for storing the first
5 bearing 33 on the inner side (output side) of the
permanent magnet electric motor 1 is disposed at the
center portion of the circular plate shape bracket 41.
The first bearing storing portion 42 is formed into,
for example, a substantially bottomed cylindrical shape
10 by press working.
[0025] The second bearing storing portion (bearing
house portion) 43 for storing the second bearing 34 on
the inner side (opposite output side) of the permanent
magnet electric motor 1 is disposed at the center
15 portion of the output side end portion of the motor
shell 10. The second bearing storing portion 43 is
formed into, for example, a substantially bottomed
cylindrical shape similarly to the first bearing
storing portion 42. The second bearing storing portion
20 43 is disposed inward (inner diameter side) relative to
the annular permanent magnet portion 31 in the radial
direction of the rotor 3. The end surface portion 13 of
the motor shell 10 includes a connection portion 14
that is connected to a flange portion 432 (to be
25 described later) of the second bearing storing portion
43.
14
[0026] As shown in Figs. 2 and 5, the first bearing
storing portion (bearing house portion) 42 includes a
tubular portion 421 that holds the outer race side of
the first bearing 33 from the radial direction, an
5 annular flange portion 422 that extends outward in the
radial direction of the rotor 3 from one end portion of
the tubular portion 421 in the rotation axis C
direction, and a coronal portion 423 that extends
inward in the radial direction from the other end
10 portion of the tubular portion 421 in the rotation axis
C direction. The coronal portion 423 covers the other
end side of the first bearing 33 in the rotation axis C
direction. The outer circumferential edge of the
annular flange portion 422 is located inward (inner
15 circumferential side) in the radial direction of the
rotor 3 relative to the permanent magnet portion 31. In
other words, the first bearing storing portion 42 is
formed so as not to overlap with the permanent magnet
portion 31 as viewed from the rotation axis C direction
20 of the rotor 3.
[0027] Specifically, the first bearing storing
portion 42 (bearing house portion of the bracket 41) is
disposed inward (inner diameter side) in the radial
direction of the rotor 3 relative to the permanent
25 magnet portion 31, as viewed from the rotation axis C
direction. Further, the outer circumferential edge
15
portion (edge portion on the outer diameter side) of
the flange portion 422 of the first bearing storing
portion 42 (bearing house portion) is covered with
resin that is a non-magnetic substance. Specifically,
5 in the bracket 41, the outer circumferential edge
portion of the flange portion 422 of the first bearing
storing portion 42 is covered with the non-magnetic
portion 44 made of resin.
[0028] As described above, the bracket 41 is formed
10 by the first bearing storing portion (magnetic portion)
42, which is one of the pair of bearing storing
portions (bearing house portions), and the non-magnetic
portion 44 (end surface portion). The first bearing
storing portion (magnetic portion) 42 is disposed on
15 the inner diameter side relative to the permanent
magnet portion 31 in the radial direction of the rotor
3, and thus can prevent the flange portion 422 of the
first bearing storing portion 42 serving as a magnetic
portion from facing the permanent magnet portion 31 in
20 the rotation axis C direction. This makes it possible
to suppress a leakage flux flowing from the permanent
magnet portion 31 to the first bearing storing portion
(magnetic portion) 42. Furthermore, in the first
bearing storing portion (magnetic portion) 42, the
25 outer circumferential edge portion of the flange
portion 422, which is disposed close to the permanent
16
magnet portion 31 of the rotor 3, is covered with the
non-magnetic portion 44. This makes it possible to
block the path of the leakage flux flowing from the
permanent magnet portion 31 to the first bearing
5 storing portion (bearing house portion) 42 formed of a
magnetic substance by the non-magnetic portion 44
formed of a non-magnetic substance, and thus further
possible to suppress the leakage flux flowing from the
permanent magnet portion 31 to the first bearing
10 storing portion 42.
[0029] Note that such a structure for suppressing
the leakage flux can be applied to not only the first
bearing storing portion 42 side but also the second
bearing storing portion 43 side. At that time, the
15 second bearing storing portion 43 is formed into the
shape similar to that of the first bearing storing
portion 42 and includes a tubular portion 431 that
holds the outer race side of the second bearing 34 from
the radial direction, an annular flange portion 432
20 that extends outward in the radial direction of the
rotor 3 from one end portion of the tubular portion 431
in the rotation axis C direction, and a coronal portion
433 that extends inward in the radial direction from
the other end portion of the tubular portion 431 in the
25 rotation axis C direction. Additionally, the second
bearing storing portion 43 is disposed on the inner
17
diameter side relative to the permanent magnet portion
31 in the radial direction of the rotor 3. Further, the
outer circumferential edge portion of the flange
portion 422 of the second bearing storing portion 43 is
5 covered with the end surface portion 13 (connection
portion 14) of the resin motor shell 10 that is a nonmagnetic
substance. This makes it possible to suppress
the leakage flux flowing from the permanent magnet
portion 31 to the second bearing storing portion 43.
10 [0030] The non-magnetic portion (end surface
portion) 44 of the bracket 41 includes the connection
portion 45 connected to the first bearing storing
portion (bearing house portion) 42. The connection
portion 45 is formed into a substantially tubular shape,
15 and the flange portion 422 of the first bearing storing
portion (bearing house portion) 42 is inserted into and
fixed to the side surface of the tubular connection
portion 45 on the inner diameter side. Here, the
tubular portion 421 of the first bearing storing
20 portion 42 is not in contact with the non-magnetic
portion 44 of the bracket 41 (is not covered with the
non-magnetic portion 44), and only the outer
circumferential edge portion of the flange portion 422
is joined (connected) to the connection portion 45 of
25 the non-magnetic portion 44 so as to be covered
therewith. Further, a clearance portion (air gap) AG1
18
is formed between the tubular portion 421 of the first
bearing storing portion 42 and the tubular connection
portion 45 of the non-magnetic portion 44. With this
configuration, the deformation of the motor shell 10
5 due to heat, shock, or the like hardly affects the
first bearing 33. Furthermore, the contact area between
the connection portion 45 of the bracket 41 and the
flange portion 422 of the first bearing storing portion
42 can be reduced, and thus the heat generated at the
10 winding wound in the stator core 21 can be prevented
from being transmitted to the first bearing 33 via the
bracket 41. This makes it possible to suppress an
increase in temperature of the first bearing 33 and
prevent the first bearing 33 from deteriorating.
15 [0031] In this embodiment, the second bearing
storing portion 43, which is the other one of the pair
of bearing storing portions, also has the structure
similar to that of the first bearing storing portion 42.
Specifically, the motor shell 10 is formed into a
20 bottomed cylindrical shape and includes the annular
portion 12 of the motor shell 10, which is integrally
formed with the stator 2, and the end surface portion
13 of the motor shell 10, which is connected to the end
portion of the annular portion 12 and expands inward
25 (inner circumferential side) in the radial direction.
Additionally, the end surface portion 13 of the motor
19
shell 10 includes the cylindrical connection portion 14
connected to the second bearing storing portion 43.
Further, similarly to the first bearing storing portion
42, the second bearing storing portion 43, which is the
5 other one of the pair of bearing storing portions,
includes the tubular portion 431 and the flange portion
432 extending outward in the radial direction from the
tubular portion 431, and only the outer circumferential
edge portion of the flange portion 432 is inserted into
10 and fixed to the side surface of the connection portion
14 of the resin shell (motor shell 10) on the inner
diameter side. Further, a clearance portion (air gap)
AG2 is formed between the tubular portion 431 of the
second bearing storing portion 43 and the connection
15 portion 14 of the resin shell (motor shell 10).
[0032] With this configuration, the deformation of
the motor shell 10 due to heat, shock, or the like
hardly affects the second bearing 34. Furthermore, the
contact area between the connection portion 14 of the
20 motor shell 10 and the flange portion 432 of the second
bearing storing portion 43 can be reduced, and thus the
heat generated at the winding wound in the stator core
21 can be prevented from being transmitted to the
second bearing 34 via the resin shell 10. This makes it
25 possible to suppress an increase in temperature of the
second bearing 34 and prevent the second bearing 34
20
from deteriorating.
[0033] Further, as described above, the rotor 3
includes the coupling portion 35, to which the shaft 32
is fixed and which couples the permanent magnet portion
5 31 and the shaft 32 to each other. The permanent magnet
portion 31 is disposed so as to face the cylindrical
stator core 21 in the radial direction. The coupling
portion 35 is disposed on the inner diameter side of
the permanent magnet portion 31 annularly disposed. As
10 shown in Figs. 2 and 4, the coupling portion 35
includes a recess 36 that is recessed toward the center
of the coupling portion 35 in the axis direction of the
rotation axis C (rotation axis C direction). The recess
36 is formed such that the thickness of the coupling
15 portion 35 in the rotation axis C direction at the
position at which the recess 36 is formed is smaller
than the thickness of the permanent magnet portion 31
in the rotation axis C direction. Additionally, the
flange portion 422 of the first bearing storing portion
20 42 is disposed so as to overlap with the recess 36 in
the rotation axis C direction. This makes it possible
to form the annular recess 36 recessed toward the
rotation axis C direction in the rotor 3, so that the
flange portion 422 of the first bearing storing portion
25 42 can be disposed within the recess 36.
In such a manner, a part of the first bearing
21
storing portion 42 (flange portion 422) enters the
annular recess 36 recessed in the axis direction of the
rotation axis C, thus reducing the thickness of the
permanent magnet electric motor 1 in the rotation axis
5 C direction and downsizing the permanent magnet
electric motor 1 in the rotation axis C direction.
[0034] As shown in Fig. 4, terminal pins 26
electrically connected to the winding (not shown) of
the stator core 21, and bosses 27 each serving as a
10 guide used when a substrate (not shown) is attached are
provided at the end portion (upper end portion in Fig.
4) of the stator 2 on the opposite output side in the
rotation axis C direction.
The bracket 41 functions as an insulation cover
15 for preventing the terminal pins 26 from being exposed
to the outside of the permanent magnet electric motor 1.
In this embodiment, the terminal pins 26 are provided
at three positions, and the bracket 41 is attached to
the motor shell 10 so as to cover up those three
20 positions.
[0035] The bracket 41 includes a cover main body 414
to be attached along the upper end surface of the
stator 2 and a fitting portion 415 integrally formed
with the cover main body 414. The cover main body 414
25 and the fitting portion 415 correspond to the nonmagnetic
portion 44 (end surface portion).
22
The cover main body 414 is formed into a circular
plate shape as a whole. As shown in Fig. 3, the fitting
portion 415 is formed as an annular projection disposed
at the outer circumferential edge portion of the cover
5 main body 414. The fitting portion 415 is fitted into
the end portion of the motor shell 10 on the opposite
output side (upper end surface of the motor shell 10 in
Fig. 4) from the rotation axis C direction, so that the
motor shell 10 (main body) and the bracket 41 are
10 aligned with each other, and the first bearing 33 is
stored in the first bearing storing portion 42 of the
bracket 41 as shown in Fig. 2.
[0036] The motor shell 10 includes the three guard
portions 102 arranged at regular intervals in the
15 circumferential direction at the end portion of the
rotation axis C on the opposite output side. Note that
any number of guard portions 102, such as two or six
guard portions 102, may be provided, and the plurality
of guard portions 102 need not be arranged at regular
20 intervals. Those three guard portions 102 each protrude
into a trapezoidal shape in the radial direction of the
stator 2 (permanent magnet electric motor 1) and each
have a predetermined thickness in the rotation axis C
direction.
25 As shown in Figs. 1 and 4, each guard portion 102
includes a cutout portion 104 for fitting a
23
vibrationproof rubber bush 6 thereinto, the cutout
portion 104 being formed from the outside in the radial
direction of the stator 2 (permanent magnet electric
motor 1) to the inner radial direction. This cutout
5 portion 104 is formed so as to connect a hole formed in
each guard portion 102 to penetrate in the rotation
axis C direction and the outer circumferential edge of
the guard portion 102 to each other. Furthermore, each
guard portion 102 includes the screw hole 103, through
10 which the above-mentioned bracket 41 is screwed.
The lower surface (surface on the output side) of
each guard portion 102 includes a circular recess
portion 106 formed to easily hold the vibrationproof
rubber bush 6 (see Figs. 1 and 4).
15 [0037] As shown in Fig. 5, any one of the three
guard portions 102 includes a slitted groove 105 for
arranging the electrically conductive member 5 for
measures against electrolytic corrosion (see Fig. 5)
along the rotation axis C direction, the slitted groove
20 105 being formed from the position on the most inner
diameter side of the cutout portion 104 in the radial
direction of the stator 2 (permanent magnet electric
motor 1) toward the center axis 32. Along this slitted
groove 105, a slitted groove for the electrically
25 conductive member 5 is also formed on the side surface
and the end surface portion 13 (surface on the output
24
side) of the motor shell 10 so as to extend in the axis
direction of the center axis 32 and the radial
direction (not shown).
The electrically conductive member 5 is a strip-
5 shaped member for electrical conduction between the
first bearing 33 and the second bearing 34. The
electrically conductive member 5 is formed by, for
example, punching a steel plate into a strip shape and
bending the obtained steel plate into a squared U shape
10 along the outer surfaces of the motor shell 10 and the
bracket 41 (see Fig. 5). The electrically conductive
member 5 allows the potentials of the first bearing 33
and the second bearing 34 on the outer race side to be
the same, and thus the generation of electrolytic
15 corrosion can be suppressed.
[0038] Here, when the bracket 41 is fitted into the
motor shell 10, the slitted groove 416 of the bracket
41 and the slitted groove 105 formed in the outer
surface of the motor shell 10 become continuous, and
20 both the slitted grooves become a guide into which the
strip-shaped electrically conductive member 5 is to be
embedded. This makes it possible to prevent the stripshaped
electrically conductive member 5 from protruding
from the surface of the shell of the permanent magnet
25 electric motor 1 and from dropping. As shown in Fig. 5,
the electrically conductive member 5 is disposed to
25
extend from the position of the flange portion 422 of
the first bearing storing portion 42 to the position of
the flange portion 432 of the second bearing storing
portion 43 through the slitted groove 416 of the
5 bracket 41, the slitted groove 105 of the guard portion
102, and the slitted groove of the outer
circumferential surface of the motor shell 10.
Further, before the vibrationproof rubber bush 6
is fitted into the guard portion 102, the electrically
10 conductive member 5 is inserted into the slitted groove
105 in advance, so that the vibrationproof rubber bush
6 can press the electrically conductive member 5 from
the outside, and the electrically conductive member 5
can be prevented from dropping.
15 [0039] As described above, in this embodiment, the
bearing house portions (first bearing storing portion
42, second bearing storing portion 43) each formed of a
magnetic substance are disposed so as not to face the
annular permanent magnet portion 31 in the rotation
20 axis C direction. Additionally, the outer
circumferential edge portion of the flange portion 422
of the bearing house portion 42 is covered with the
non-magnetic portion 44 formed of a non-magnetic
substance so as not to generate the path of the
25 magnetic flux, which short-circuits between the bearing
house portions 42 and 43 and the rotor 3 (permanent
26
magnet portion 31) in the radial direction of the
stator 2 (permanent magnet electric motor 1).
[0040] This makes it possible to suppress the
generation of a leakage flux by blocking the path of
5 the leakage flux flowing from the permanent magnet
portion 31 to the bearing house portions 42 and 43 even
if the bearing house portion 42 is disposed close to
the permanent magnet portion 31 in the axis direction
of the rotation axis C (rotation axis C direction).
10 Further, since the bearing house portion 42 can be
disposed close to the permanent magnet portion 31 in
the axis direction of the rotation axis C (rotation
axis C direction), so that the permanent magnet
electric motor 1 can be downsized in the axis direction
15 of the rotation axis C.
Reference Signs List
[0041]
1 permanent magnet electric motor
10 motor shell (main body)
20 12 annular portion
13 end surface portion
2 stator
21 stator core
3 rotor
25 31 permanent magnet portion (magnetized portion)
32 shaft
27
33 first bearing
34 second bearing
35 coupling portion
36 recess
5 41 bracket
42 first bearing storing portion (bearing house
portion)
421 tubular portion
422 flange portion
10 423 coronal portion
43 second bearing storing portion (bearing house
portion)
44 non-magnetic portion (end surface portion)
45 connection portion
15 AG1, AG2 clearance portion (air gap)
C rotation axis

Claims
[1] A permanent magnet electric motor, comprising:
a columnar rotor including a permanent magnet
portion annularly disposed;
5 a shaft disposed along a rotation axis of the
rotor;
a cylindrical stator core disposed on an outer
circumferential side of the rotor;
a main body including a shell integrally formed
10 with the stator core;
a bracket attached to one end side of the main
body; and
a bearing that rotatably supports the shaft,
wherein
15 the bracket includes a bearing house portion that
stores the bearing, and a non-magnetic portion that is
connected to the bearing house portion,
the bearing house portion is disposed on an inner
diameter side relative to the permanent magnet portion
20 as viewed from an axis direction of the rotation axis,
and
an edge portion of the bearing house portion on an
outer diameter side is covered with the non-magnetic
portion.
25 [2] The permanent magnet electric motor according to
claim 1, wherein
29
the bearing house portion includes a tubular
portion and an annular flange portion extending outward
in a radial direction from one end side of the tubular
portion, and
5 an outer edge of the flange portion is covered
with the non-magnetic portion.
[3] The permanent magnet electric motor according to
claim 2, wherein
the permanent magnet portion of the rotor faces
10 the stator core in the radial direction,
the rotor further includes a coupling portion that
couples the permanent magnet portion and the shaft to
each other,
the coupling portion includes an annular recess
15 that is disposed on an inner diameter side of the
permanent magnet portion and is recessed toward the
center of the coupling portion in the axis direction,
and
the flange portion of the bearing house portion is
20 disposed to overlap with the recess in the axis
direction.
[4] The permanent magnet electric motor according to
claims 1 to 3, wherein
the permanent magnet portion is a bonded magnet.