Technical Field
5 [0001] The present invention relates to an innerrotor
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 electric
motor has been conventionally known, in which a
columnar rotor including a permanent magnet is disposed
coaxially with a cylindrical stator, which generates a
rotating magnetic field, on the inner diameter side of
15 the cylindrical stator. This electric motor is, for
example, used to rotationally drive a blower fan
mounted in an air conditioner.
[0003] In the electric motor of Patent Literature 1
as this type of electric motor, a bearing house portion
20 (bearing bracket) that holds a bearing is disposed
close to the rotor in the axis direction of the stator,
so that the electric motor is downsized in the axis
direction. Further, the stator core is covered with a
molded resin to form a resin shell.
25 Citation List
Patent Literature
3
[0004] Patent Literature 1: Japanese Patent
Application Laid-open No. 2011-109861
Disclosure of Invention
Technical Problem
5 [0005] Here, in the electric motor of Patent
Literature 1, the resin shell that covers the stator
covers the bearing house portion as well. In general,
the resin is more likely to expand and contract due to
heat than metal, and if the resin shell covering the
10 bearing house portion is deformed due to heat, the
bearing house portion or the bearing is deformed along
with the deformation of the resin shell, which may
reduce the slidability of the bearing.
[0006] In this regard, it is an object of the
15 present invention to provide an electric motor that can
be downsized in an axis direction of a rotation axis
and can suppress the deformation of a bearing and a
bearing house portion along with the deformation of a
resin shell.
20 Solution to Problem
[0007] According to an aspect of the present
invention, there is provided an electric motor
including: a columnar rotor; a shaft disposed along a
rotation axis of the rotor; a cylindrical stator core
25 disposed on an outer circumferential side of the rotor;
a resin shell that covers the stator core; a bearing
4
that rotatably supports the shaft; and a bearing house
portion that stores the bearing. The resin shell
includes an annular portion integral with the stator
core, and an end surface portion connected to an end
5 portion of the annular portion and expanding from the
annular portion to an inner circumferential side. The
end surface portion includes a connection portion to be
connected to the bearing house portion. The bearing
house portion includes a tubular portion and a flange
10 portion extending from an end of the tubular portion to
the outer circumferential side. An outer
circumferential edge portion of the flange portion is
fixed to the connection portion of the resin shell.
[0008] According to the present invention, it is
15 possible to downsize an electric motor in an axis
direction of a rotation axis and to suppress the
deformation of a bearing and a bearing house portion
along with the deformation of a resin shell.
Brief Description of Drawings
20 [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
of the permanent magnet electric motor according to the
25 present invention.
[Fig. 3] Fig. 3 is a perspective view of a bracket of
5
the permanent magnet electric motor according to the
present invention.
[Fig. 4] Fig. 4 is an overall perspective view of the
permanent magnet electric motor according to the
5 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.
Mode(s) for Carrying Out the Invention
10 [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
similar reference symbols. It should be noted that the
15 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
exemplifies apparatuses and methods for embodying the
20 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.
Various modifications can be made to the technical idea
25 of the present invention within the technical scope
defined by the claims.
6
[0012] Hereinafter, an electric motor according to
an embodiment of the present invention will be
described.
[0013]
5 Figs. 1 to 5 are views for describing a
configuration of an electric motor 1 of this embodiment.
As shown in those figures, the electric motor 1 is a
brushless DC motor, for example. The electric motor 1
is, for example, used to rotationally drive a blower
10 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 electric motor
1 of this embodiment includes a stator 2, a rotor 3, a
motor shell (casing, main body) 10, and a bracket 41.
15 Hereinafter, an inner-rotor permanent magnet
electric motor 1 will be described as an example, in
which a columnar rotor 3 including a permanent magnet
portion 31 is rotatably disposed inward (inner
circumferential side) in the radial direction of a
20 cylindrical stator 2 that generates a rotating magnetic
field.
[0015]
As shown in Fig. 2, the rotor 3 includes an
annular permanent magnet portion 31 and a coupling
25 portion 35, which is disposed on the inner diameter
side relative to the permanent magnet portion 31 and
7
couples the permanent magnet portion 31 and a shaft 32
to each other. The shaft 32 is fixed to the columnar
rotor 3 along the center axis of the rotor 3. In this
embodiment, the permanent magnet portion 31 and the
5 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
the permanent magnet portion 31 is magnetized to cause
the permanent magnet portion 31 to function as a
10 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
alternately appear in the circumferential direction
thereof. Thus, a part of a yoke for concentrating the
15 flow of the magnetic flux of the permanent magnet
portion 31 becomes unnecessary, and the leakage flux
can be suppressed.
[0016] Note that the permanent magnet portion 31 and
the coupling portion 35 may be formed separately. For
20 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
31), which are obtained by sintering a powder-like
ferrite magnetic substance in a mold, are annularly
25 attached to the outer circumferential surface of a
rotor core (corresponding to the coupling portion 35).
8
[0017] The stator 2 includes a stator core 21
including a cylindrical yoke portion (not shown) and a
plurality of teeth portions (not shown) extending from
the yoke portion to the inner diameter side, and
5 winding (not shown) wound around the teeth portion via
an insulator. The stator core 21 is formed of, for
example, silicon steel of a soft magnetic material. The
stator 2 is covered with the motor shell 10 formed of
resin by resin integral molding, except for the inner
10 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 circumferential side of the rotor 3 (outward
15 in the radial direction of the 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 in the
radial direction of the stator 2. In other words, the
20 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.
[0018] The motor shell 10 may have any shape. For
example, the motor shell 10 may be formed into a hollow
25 cylindrical shape having an open end surface on one
side (in the embodiment, the opposite output side of
9
the shaft 32) in the axis direction of the center axis
of the electric motor 1, that is, the rotation axis of
the rotor 3 (hereinafter, rotation axis C). In this
embodiment, the motor shell 10 includes an annular
5 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. The end surface portion 13 expands
inward in the radial direction (inner diameter
direction) from the annular portion.
10 [0019] The rotor 3 is rotatably disposed on the
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 is annularly disposed on
15 the outer side (outer circumferential side) in the
radial direction of the rotor 3 so as to face the
stator core 21.
[0020] The rotor 3 is fixed to the circumference of
the shaft 32. The shaft 32 is rotatably supported
20 (held) by a first bearing 33 and a second bearing 34
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
25 34 is stored (held) in a second bearing storing portion
43 (bearing house portion) to be described later, so
10
that the rotor 3 is rotatably supported. The first
bearing storing portion 42 and the second bearing
storing portion 43 are formed of, for example, a
magnetic substance of chromium-nickel-based stainless
5 steel.
[0021]
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
10 bearing 33. The second bearing 34 is fixed to the other
end side (output side) of the shaft 32 at the inner
race side of the second bearing 34. The first bearing
33 and the second bearing 34 (a pair of bearings)
cooperate to rotatably support (pivotally support) the
15 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 the second bearing 34.
[0022] The bracket 41 includes the first bearing
storing portion 42 that is formed of a magnetic
20 substance and stores the first bearing 32, and a nonmagnetic
portion 44 (end surface portion) formed of a
non-magnetic substance (e.g., resin). In the motor
shell 10 of the electric motor 1, the bracket 41 is
disposed at an end in the rotation axis C direction,
25 that is, disposed on the opposite output side of the
shaft 32. The non-magnetic portion 44 (end surface
11
portion) of the bracket 41 includes a connection
portion 45 connected to the first bearing storing
portion 42 (see Figs. 2, 3, and 5). The non-magnetic
portion 44 of the bracket 41 is integrally formed with
5 the first bearing storing portion 42, which is a
magnetic portion, by insert molding. The non-magnetic
portion 44 (end surface portion) is connected to the
first bearing storing portion 42 (bearing house
portion) at the connection portion 45.
10 [0023] The bracket 41 is attached to the end portion
of the motor shell 10 on the opposite output side by
using screws to serve as a lid for covering the opening
of the motor shell 10 (main body). Note that the
opening of the motor shell 10 may be provided toward
15 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.
[0024] The non-magnetic portion 44 (end surface
portion) of the bracket 41 is formed into a
20 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
the radial direction. The non-magnetic portion 44 of
the bracket 41 forms a resin shell of the electric
25 motor 1 together with the motor shell 10. Additionally,
the non-magnetic portion 44 includes protrusions 410,
12
which protrude outward in the radial direction relative
to the outer circumferential surface of the motor shell
10, as viewed from the rotation axis C direction. The
protrusions 410 each abut on the basal end portion of a
5 guard portion 102 of the motor shell 10. The guard
portion 102 will be described later.
The protrusions 410 provided to the bracket 41 are
formed as many as the guard portions 102 provided to
the motor shell 10 (three positions). For example, the
10 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
hole 413 penetrating in the rotation axis C direction.
[0025] Note that the bracket 41 includes a slitted
15 groove 416 for providing an electrically conductive
member 5 for measures against electrolytic corrosion,
which will be described later, in the outer surface
exposed to the outside in the electric motor 1 after
assembling (see Figs. 1 and 3).
20 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
portion 44 to be described later) to the outer
circumferential surface of the bracket 41, and further
25 extends in the axis direction from there to the
position abutting on the motor shell 10.
13
[0026] The bracket 41 is fitted into the motor shell
10 and then screwed at screw holes 103 (to be described
later) of the guard portions 102 of the motor shell 10
via the screw through holes 413 (see Fig. 1).
5 Further, the first bearing storing portion
(bearing house portion) 42 for storing the first
bearing 33 on the inner side (output side) of the
electric motor 1 is disposed at the center portion of
the circular plate shape bracket 41. The first bearing
10 storing portion 42 is formed into, for example, a
substantially bottomed cylindrical shape by press
working.
[0027] The second bearing storing portion (bearing
house portion) 43 for storing the second bearing 34 on
15 the inner side (opposite output side) of the electric
motor 1 is disposed at the center 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
20 the first bearing storing portion 42. The second
bearing storing portion 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
25 includes a connection portion 14 that is connected to a
flange portion 432 (to be described later) of the
14
second bearing storing portion 43.
[0028] As shown in Figs. 2 and 5, the first bearing
storing portion 42, which is one of the pair of bearing
house portions, includes a tubular portion 421 that
5 holds the outer race side of the first bearing 33 from
the radial direction, an 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
10 423 that extends inward in the radial direction from
the other end 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
15 circumferential edge of the annular flange portion 422
is located inward (inner 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
20 overlap with the permanent magnet portion 31 as viewed
from the rotation axis C direction of the rotor 3.
[0029] Specifically, the first bearing storing
portion 42 (bearing house portion) is disposed inward
(inner diameter side) in the radial direction of the
25 rotor 3 relative to the permanent magnet portion 31, as
viewed from the rotation axis C direction. Further, the
15
outer circumferential edge portion of the flange
portion 422 of the first bearing storing portion 42
(edge portion of the first bearing storing portion 42
on the outer diameter side) is covered with resin that
5 is a non-magnetic substance. Specifically, 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.
10 [0030] As described above, the bracket 41 is formed
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
15 storing portion (magnetic portion) 42 is disposed on
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
20 portion from facing the permanent magnet portion 31 in
the rotation axis C direction.
[0031] This makes it possible to suppress a leakage
flux flowing from the permanent magnet portion 31 to
the first bearing storing portion (magnetic portion,
25 bearing house portion) 42. Furthermore, in the first
bearing storing portion 42, the outer circumferential
16
edge portion of the flange portion 422, which is
disposed close to the permanent 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
5 leakage flux flowing from the permanent magnet portion
31 to the first bearing storing portion (magnetic
portion, bearing house portion) 42 formed of a magnetic
substance by the non-magnetic portion (end surface
portion) 44 formed of a non-magnetic substance, and
10 thus further possible to suppress the leakage flux
flowing from the permanent magnet portion 31 to the
first bearing storing portion 42.
[0032] Note that such a structure for suppressing
the leakage flux can be applied to not only the first
15 bearing storing portion 42 side but also the second
bearing storing portion 43 side. At that time, the
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
20 holds the outer race side of the second bearing 34 from
the radial direction, an annular flange portion 432
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
25 433 that extends inward in the radial direction from
the other end portion of the tubular portion 431 in the
17
rotation axis C direction. Additionally, the second
bearing storing portion 43 is disposed on the inner
diameter side relative to the permanent magnet portion
31 in the radial direction of the rotor 3.
5 [0033] Further, the outer circumferential edge
portion of the flange portion 422 of the second bearing
storing portion 43 is covered with the end surface
portion 13 (connection portion 14) of the resin motor
shell 10 that is a non-magnetic substance. This makes
10 it possible to suppress the leakage flux flowing from
the permanent magnet portion 31 to the second bearing
storing portion 43. The configuration for suppressing
such a leakage flux may be applied to either one of or
both of the first bearing storing portion 42 and the
15 second bearing storing portion 43, which are the pair
of bearing house portions.
[0034] The non-magnetic portion (end surface
portion) 44 of the bracket 41 includes the connection
portion 45 connected to the first bearing storing
20 portion (bearing house portion) 42. The connection
portion 45 is formed into a substantially tubular shape,
and the flange portion 422 of the bearing house portion
(first bearing storing portion 42) formed of a magnetic
substance is inserted into and fixed to the side
25 surface of the tubular connection portion 45 on the
inner diameter side. Here, the tubular portion 421 of
18
the first bearing storing 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
5 portion 422 is joined (connected) to the connection
portion 45 of the non-magnetic portion (end surface
portion) 44 so as to be covered therewith. Further, a
clearance portion (air gap) AG1 is formed between the
tubular portion 421 of the first bearing storing
10 portion 42 (bearing house portion) and the tubular
connection portion 45 of the non-magnetic portion (end
surface portion) 44 forming the resin shell.
[0035] With this configuration, the deformation of
the resin shell (motor shell 10, end surface portion
15 (non-magnetic portion) 44) 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
20 heat generated at the 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
25 deteriorating.
[0036] Here, regarding the first bearing storing
19
portion 42 side (opposite output side), the first
bearing storing portion 42 being one of the pair of
bearing storing portions, the annular portion 12 of the
motor shell 10, which is integral with the stator 2,
5 and the end surface portion (resin non-magnetic portion
44 of bracket 41) connected to the end portion of the
tubular portion and expanding inward (inner
circumferential side) in the radial direction are
separately formed to serve as the resin shell of the
10 motor 1. However, the tubular portion and the end
surface portion in the resin shell may be integrally
formed. In this embodiment, on the second bearing
storing portion 43 side, the second bearing storing
portion 43 being the other one of the pair of bearing
15 storing portions, the tubular portion and the end
surface portion are integrally formed as the resin
shell.
[0037] Specifically, on the second bearing storing
portion 43 side (output side), the second bearing
20 storing portion 43 being the other one of the pair of
bearing storing portions, the second bearing storing
portion 43 is formed into a shape similar to that of
the first bearing storing portion 42. Note that the
structures of the first bearing storing portion 42 and
25 the second bearing storing portion 43 may be
communalized, and the first bearing storing portion 42
20
and the second bearing storing portion 43 may be
disposed upside down to communalize their constituent
parts. The motor shell 10 is formed into a
substantially bottomed cylindrical shape and includes
5 the annular portion 12 of the motor shell 10, which is
integral 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 in the rotation axis
C direction and expands inward (inner circumferential
10 side) in the radial direction. Additionally, the end
surface portion 13 of the motor 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
15 bearing storing portion 43 also includes 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 and fixed to the side surface of the
20 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 portion 14 of the resin shell (motor
25 shell 10).
[0038] With this configuration, the deformation of
21
the resin shell (annular portion 12 and end surface
portion 13 of motor shell 10) due to heat, shock, or
the like hardly affects the second bearing 34.
Furthermore, the contact area between the connection
5 portion 14 of the 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
10 shell. This makes it possible to suppress an increase
in temperature of the first bearing 33 and prevent the
first bearing 33 from deteriorating.
[0039] As described above, the rotor 3 includes the
coupling portion 35, to which the shaft 32 is fixed and
15 which couples the permanent magnet portion 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
20 magnet portion 31 annularly disposed. As shown in Figs.
2 and 4, the coupling portion 35 includes an annular
recess 36 that is recessed 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
25 portion 35 in the rotation axis C direction at the
position at which the recess 36 is formed is smaller
22
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
42 is disposed so as to overlap with the recess 36,
5 which is formed in the coupling portion 35, 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 42 can
10 be disposed within the recess 36.
[0040] In such a manner, a part of the first bearing
storing portion 42 (flange portion 422) enters the
annular recess 36 recessed in the axis direction of the
rotation axis C (rotation axis C direction), thus
15 reducing the thickness of the electric motor 1 in the
rotation axis C direction and downsizing the electric
motor 1 in the rotation axis C direction.
[0041] As shown in Fig. 4, terminal pins 26
electrically connected to the winding (not shown) of
20 the stator core 21, and bosses 27 each serving as a
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.
25 The bracket 41 functions as an insulation cover
for preventing the terminal pins 26 from being exposed
23
to the outside of the 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 positions.
5 [0042] 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
and the fitting portion 415 correspond to the non10
magnetic portion 44 (end surface portion).
The cover main body 414 is formed into a
substantially 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
15 circumferential edge portion of the cover 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
20 shell 10 (main body) and the bracket 41 are aligned
with each other, and the first bearing 33 is stored in
the first bearing storing portion 42 provided to the
bracket 41 as shown in Fig. 2.
[0043] The motor shell 10 includes the three guard
25 portions 102 arranged at regular intervals in the
circumferential direction at the end portion of the
24
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
5 intervals. Those three guard portions 102 each protrude
into a trapezoidal shape in the radial direction of the
stator 2 (electric motor 1) and each have a
predetermined thickness in the rotation axis C
direction.
10 [0044] As shown in Figs. 1 and 4, each guard portion
102 includes a cutout portion 104 for fitting a
vibrationproof rubber bush 6 thereinto, the cutout
portion 104 being formed from the outside in the radial
direction of the stator 2 (electric motor 1) to the
15 inner radial direction. This cutout 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
20 guard portion 102 includes the screw hole 103, through
which the above-mentioned bracket 41 is screwed.
The lower surface (surface on the output side) of
each guard portion 102 includes a recess portion 106
formed to easily hold the vibrationproof rubber bush 6
25 (see Figs. 1 and 4).
[0045] As shown in Fig. 5, any one of the three
25
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
5 105 being formed at the position on the most inner
diameter side of the cutout portion 104 in the radial
direction of the stator 2 (electric motor 1). Along
this slitted groove 105, a slitted groove for the
electrically conductive member 5 is also formed on the
10 side surface and the end surface portion 13 (surface on
the output side) of the motor shell 10 so as to extend
in the axis direction of the rotation axis C and the
radial direction (not shown).
[0046] The electrically conductive member 5 is a
15 strip-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 substantially U
20 shape (squared U shape). The electrically conductive
member 5 is disposed 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
25 the outer race side to be the same, and thus the
generation of electrolytic corrosion on the bearings
26
can be suppressed.
[0047] 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
5 surface of the motor shell 10 become continuous, and
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
10 from the surface of the shell of the permanent magnet
electric motor 1 and from dropping. As shown in Fig. 5,
the electrically conductive member 5 is disposed to
extend from the position of the flange portion 422 of
the first bearing storing portion 42 to the position of
15 the flange portion 432 of the second bearing storing
portion 43 through the slitted groove 416 of the
bracket 41, the slitted groove 105 of the guard portion
102, and the slitted groove of the outer surface of the
motor shell 10 (not shown).
20 [0048] As described above, in the electric motor 1,
the two bearings of the first bearing 33 and the second
bearing 34 are disposed, and the two bearing house
portions of the first bearing storing portion 42 and
the second bearing storing portion 43 are disposed. The
25 bearing house portions 42 and 43 store the bearings 33
and 34, respectively. Further, the electric motor 1
27
includes the electrically conductive member 5 for
electrical conduction between the two bearings 33 and
34. Additionally, at least one end portion (both end
portions in the embodiment) of the electrically
5 conductive member 5 is disposed in the clearance
portion AG1, AG2 formed between the tubular portion 421,
431 of the bearing house portion 42, 43 and the
connection portion 45, 14 of the resin shell (end
surface portion 44, 13) (see 5). With this
10 configuration, the end portion of the electrically
conductive member 5 for preventing electrolytic
corrosion is disposed in the clearance portion AG1, AG2
that is a tubular clearance, and thus it is possible to
prevent the electrically conductive member 5 from
15 dropping when the end portion of the electrically
conductive member 5 is touched by a human hand to
thereby hinder the electrical conduction between the
bearings. Further, the end portion of the electrically
conductive member 5 can be press-fitted into the
20 clearance portion AG1, AG2 described above to be easily
fixed to the outer circumferential surface of the
bearing house portion 42, 43.
Further, before the vibrationproof rubber bush 6
is fitted into the guard portion 102, the electrically
25 conductive member 5 is inserted into the slitted groove
105 in advance, so that the vibrationproof rubber bush
28
6 can press the electrically conductive member 5 from
the outside, and the electrically conductive member 5
can be prevented from dropping.
[0049] As described above, in this embodiment, since
5 the resin shell (motor shell 10, non-magnetic portion
44) having a large amount of deformation due to heat
does not cover the entire bearing house portions 42 and
43, the deformation of the first and second bearings 33
and 34 and the bearing house portions 42 and 43 along
10 with the deformation of the resin shell can be
suppressed. Further, the heat generated at the winding
wound in the stator core 21 can be prevented from being
transmitted to the bearings 33 and 34 via the resin
shell.
15 [0050] Meanwhile, the resin shell (connection
portion 14 of motor shell 10, connection portion 45 of
bracket 41) is connected to the outer edge of the
flange portion 422, 432 of the bearing house portion 42,
43, so that the bearing house portion 42, 43 can be
20 fixed to the resin shell.
Further, it is possible to prevent the pair of
bearings (first bearing 33 and second bearing 34) and
the pair of bearing house portions (first bearing
storing portion 42, second bearing storing portion 43)
25 from protruding in the axis direction of the rotation
axis C and to downsize the electric motor 1 in the
29
direction of the rotation axis.
Reference Signs List
[0051]
1 electric motor
5 10 motor shell (resin shell)
12 annular portion
13 end surface portion
14 connection portion
2 stator
10 21 stator core
3 rotor
31 permanent magnet portion
32 shaft
33 first bearing
15 34 second bearing
35 coupling portion
36 recess
41 bracket
42, 43 bearing storing portion (bearing house
20 portion)
421, 431 tubular portion
422, 432 flange portion
423, 433 coronal portion
44 end surface portion (non-magnetic portion)
25 45 connection portion
5 electrically conductive member
30
AG1, AG2 clearance portion
C rotation axis

Claims
[1] An electric motor, comprising:
a columnar rotor;
a shaft disposed along a rotation axis of the
5 rotor;
a cylindrical stator core disposed on an outer
circumferential side of the rotor;
a resin shell that covers the stator core;
a bearing that rotatably supports the shaft; and
10 a bearing house portion that stores the bearing,
wherein
the resin shell includes an annular portion
integral with the stator core, and an end surface
portion connected to an end portion of the annular
15 portion and expanding from the annular portion to an
inner circumferential side,
the end surface portion includes a connection
portion to be connected to the bearing house portion,
the bearing house portion includes a tubular
20 portion and a flange portion extending from an end of
the tubular portion to the outer circumferential side,
and
an outer circumferential edge portion of the
flange portion is fixed to the connection portion of
25 the resin shell.
[2] The electric motor according to claim 1, wherein
32
the tubular portion of the bearing house portion
and the connection portion of the resin shell form a
clearance portion therebetween.
[3] The electric motor according to claim 2, wherein
5 the two bearings and the two bearing house
portions are disposed,
the electric motor further includes an
electrically conductive member for electrical
conduction between the two bearings, and
10 at least one end portion of the electrically
conductive member is disposed in the clearance portion.
[4] The electric motor according to claims 1 to 3,
wherein
the connection portion of the resin shell is
15 formed into a tubular shape, and
the flange portion of the bearing house portion is
inserted into and fixed to a side surface of the
connection portion on an inner diameter side.
20
33
Abstract
[Abstract]
ELECTRIC MOTOR
[Object] To provide an electric motor that can be
5 downsized in a rotation axis direction and can also
suppress the deformation of a bearing and a bearing
house portion along with the deformation of a resin
shell.
[Solving Means] An electric motor according to an
10 aspect of the present invention includes: a columnar
rotor; a shaft disposed along a rotation axis of the
rotor; a cylindrical stator core disposed on an outer
circumferential side of the rotor; a resin shell that
covers the stator core; a bearing that rotatably
15 supports the shaft; and a bearing house portion that
stores the bearing. The resin shell includes an annular
portion integral with the stator core, and an end
surface portion connected to an end portion of the
annular portion and expanding from the annular portion
20 to an inner circumferential side. The end surface
portion includes a connection portion to be connected
to the bearing house portion. The bearing house portion
includes a tubular portion and a flange portion
extending from an end of the tubular portion to the
25 outer circumferential side in the radial direction. An
outer circumferential edge portion of the flange
34
portion is fixed to the connection portion of the resin
shell.
[Selected Drawing] Fig. 5