Technical Field
5 [0001] The present invention relates to an electric
motor.
Background Art
[0002] In conventional electric motors, an innerrotor
electric motor has been known, in which a rotor
10 including a permanent magnet is rotatably disposed on
the inner side of a stator that generates a rotating
magnetic field. This electric motor is, for example,
used to rotationally drive a blower fan mounted in an
air conditioner.
15 Such electric motors include an electric motor in
which a circuit board is disposed in the internal space
surrounded by the shell of the electric motor, and lead
wires are connected to the circuit board.
[0003] Conventionally, the lead wires connected to
20 the circuit board disposed in the internal space of the
electric motor are drawn from the internal space of the
electric motor to the outside via through holes formed
in resin bushings (e.g., Patent Literature 1).
Citation List
25 Patent Literature
[0004] Patent Literature 1: Japanese Patent
3
Application Laid-open No. 2013-138551
Disclosure of Invention
Technical Problem
[0005] However, the step of passing lead wires
5 through bushings and the step of attaching the bushings
to the main body of the electric motor have been
required at the time of assembly of the electric motor.
This has increased the man-hour at the time of
assembly.
10 [0006] In this regard, it is an object of the
present invention to provide an electric motor that
improves assemblability without needing bushings.
Solution to Problem
[0007] According to an aspect of the present
15 invention, there is provided an electric motor
including: a main body having a bottomed cylindrical
shape having an opening on one end side; a bracket that
covers the opening; a circuit board disposed in an
internal space surrounded by the main body and the
20 bracket; and a lead wire connected to the circuit
board. Each of the main body and the bracket includes a
lead portion, the lead wire being drawn from the
internal space to an outside through the lead portion.
The lead wire is sandwiched by sandwiching portions
25 formed in the respective lead portions of the main body
and the bracket. Each of the sandwiching portions
4
includes a restriction portion that protrudes from at
least one of the main body and the bracket to another
one of them.
[0008] According to the present invention, it is
5 possible to improve assemblability without needing a
bushing that passes a lead wire therethrough.
Brief Description of Drawings
[0009] [Fig. 1] Fig. 1 is an overall perspective
view of an electric motor according to the present
10 invention.
[Fig. 2] Fig. 2 is a transverse cross-sectional view
of the electric motor according to the present
invention.
[Fig. 3] Fig. 3 is a perspective view of a bracket of
15 the electric motor according to the present invention.
[Fig. 4] Fig. 4 is an overall perspective view of the
electric motor according to the present invention,
showing a state in which the bracket of Fig. 3 is
removed.
20 [Fig. 5] Fig. 5 is a partially enlarged view of one
side of Fig. 2.
[Fig. 6] Fig. 6 is a partially enlarged view of a
lower right part of Fig. 2.
[Fig. 7] Fig. 7 is an overall side view of the
25 electric motor according to the present invention.
Mode(s) for Carrying Out the Invention
5
[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
5 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
10 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.
15 Various modifications can be made to the technical idea
of the present invention within the technical scope
defined by the claims.
[0012] Hereinafter, an electric motor according to
an embodiment of the present invention will be
20 described.
[0013]
Figs. 1 to 5 are views for describing a
configuration of an electric motor 1 of this embodiment.
As shown in those figures, this electric motor 1 is a
25 brushless DC motor, for example. The electric motor 1
is, for example, used to rotationally drive a blower
6
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
5 motor shell (casing, main body) 10, a bracket 41, a
circuit board 81 disposed in the internal space
surrounded by the motor shell 10 and the bracket 41,
and lead wires 82 electrically connected to the circuit
board 81.
10 The motor shell (main body) 10 and the bracket 41
include respective lead portions 7, through which the
lead wires 82 are drawn from the internal space of the
electric motor 1 to the outside.
[0015] As will be described later, the sandwiching
15 portions formed in the lead portions 7 of the motor
shell 10 and the bracket 41 cooperate to sandwich the
lead wires 82 from the axis direction of the rotation
axis of the electric motor 1. It is favorable that the
sandwiching portions of the motor shell 10 and the
20 bracket 41 be formed of resin in order to prevent the
lead wires from being damaged. Further, in this
embodiment, the lead portion 7 includes a first
sandwiching portion 71 and a second sandwiching portion
75 (see Fig. 2).
25 Hereinafter, an inner-rotor permanent magnet
electric motor 1 will be described as an example, in
7
which a rotor 3 including a permanent magnet portion 31
is rotatably disposed inside a stator 2 that generates
a rotating magnetic field.
[0016]
5 As shown in Fig. 2, the rotor 3 includes an
annular permanent magnet portion 31 and a coupling
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
10 to each other. The shaft 32 is disposed along the
center axis of the columnar rotor 3 and also fixed to
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
15 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 ferrite bonded magnet. Further, the
permanent magnet portion 31 is magnetized to be a polar
20 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 flow of the magnetic flux of the
permanent magnet portion 31 becomes unnecessary, and
25 the leakage flux can be suppressed.
Note that the permanent magnet portion 31 and the
8
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
5 31), which are obtained by sintering a powder-like
ferrite magnetic substance in a mold, are annularly
attached to the outer circumferential surface of a
rotor core (corresponding to the coupling portion 35).
[0017] The stator 2 includes a stator core 21
10 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
winding (not shown) wound around the teeth portions via
an insulator. The stator 2 is covered with the motor
15 shell 10 (main body) formed of resin by resin integral
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. The stator 2 is
20 disposed on the outer 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
portions of the stator core 21 face the permanent
25 magnet portion 31 of the rotor 3 in the radial
direction. In other words, the stator 2 is disposed
9
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] For example, as shown in Fig. 4, the motor
5 shell 10 as a main body is formed into a bottomed
cylindrical shape having an opening O on one side (in
the embodiment, the opposite output side of the shaft
32) in the axis direction of the center axis of the
electric motor 1, that is, the rotation axis of the
10 rotor 3 (hereinafter, rotation axis C). In this
embodiment, the motor shell 10 includes an annular
portion 12, the opening O, and an end surface portion
(bottom surface) 13 formed at the end portion on the
opposite side of the opening O (the output side of the
15 shaft 32). The rotor 3 and the board 81 are stored in
the internal space surrounded by the motor shell 10 and
the bracket 41 (see Figs. 2 and 4). Note that a part of
the motor shell 10 may be formed of metal.
[0019] The rotor 3 is rotatably disposed on the
20 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 disposed in an annular
shape is disposed on the outer side (outer
25 circumference side) in the radial direction of the
rotor 3 so as to face the stator core 21.
10
[0020] 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
fixed to the outer circumferential surface of the shaft
5 32. Further, the first bearing 33 is stored (held) in a
first bearing storing portion 42 to be described later,
and the second bearing 34 is stored (held) in a second
bearing storing portion 43 to be described later, so
that the rotor 3 is rotatably supported. The first
10 bearing storing portion 42 and the second bearing
storing portion 43 are formed of, for example, a
magnetic substance of chromium-nickel-based stainless
steel.
[0021]
15 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
20 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 coupled to the shaft 32. For example, a ball
bearing is used for each of the first bearing 33 and
25 the second bearing 34.
[0022] The bracket 41 includes the first bearing
11
storing portion 42 that is formed of a magnetic
substance and stores the first bearing 33, and a nonmagnetic
portion 44 (end surface portion) formed of a
non-magnetic substance (e.g., resin). In the motor
5 shell 10 (main body) of the permanent magnet electric
motor 1, the bracket 41 is disposed at an end in the
rotation axis C direction, that is, disposed on the
opposite output side of the shaft 32. The non-magnetic
portion (end surface portion) 44 of the bracket 41
10 includes a connection portion 45 connected to the first
bearing storing portion 42 (see Figs. 2, 3, and 5). The
non-magnetic portion (end surface portion) 44 of the
bracket 41 is integrally formed with the first bearing
storing portion 42, which is a magnetic portion, by
15 insert molding. The non-magnetic portion (end surface
portion) 44 is connected to the first bearing storing
portion 42 at the connection portion 45.
[0023] The bracket 41 is attached to the end portion
of the motor shell 10 (main body) on the opposite
20 output side by using screws to serve as a lid for
covering the opening O of the motor shell 10 (main
body). Note that the opening O of the motor shell 10
(main body) may be provided toward the output side. In
this case, the bracket 41 is disposed not on the
25 opposite output side of the shaft 32 but on the output
side of the shaft 32.
12
[0024] 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
5 outer circumferential surface of the motor shell 10 in
the radial direction. Further, the non-magnetic portion
44 (end surface portion) of the bracket 41 forms a
resin shell of the permanent magnet electric motor 1
together with the motor shell 10. Additionally, the
10 non-magnetic portion 44 includes protrusions 410, 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
15 leg portion 107 of the motor shell 10. The leg portion
107 will be described later. The protrusion 410 of the
bracket 41 is disposed so as to overlap with the leg
portion 107 in the rotation axis C direction.
[0025] The protrusions 410 of the bracket 41 are
20 formed as many as the leg portions 107 provided to the
motor shell 10 (three positions). For example, the
protrusions 410 are each formed into a trapezoidal
shape as viewed from the rotation axis C direction and
each include, at the center portion thereof, a screw
25 through hole 413 penetrating in the rotation axis C
direction.
13
[0026] 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, on the outer surface
5 side 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
10 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.
[0027] The bracket 41 is fitted into the motor shell
15 10 (main body) and then screwed at leg-portion-side
fastening portions (screw holes) 103 (to be described
later) of the leg portions 107 of the motor shell 10
via the screw through holes 413 (see Fig. 1).
Further, the first bearing storing portion
20 (bearing house portion) 42 for storing the first
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,
25 for example, a substantially bottomed cylindrical shape
by press working. Further, the non-magnetic portion 44
14
of the bracket 41 includes, at the inner diameter side
thereof, the tubular connection portion 45 connected to
the first bearing storing portion 42 (see Figs. 2 and
5).
5 [0028] The second bearing storing portion (bearing
house portion) 43 for storing the second bearing 34 on
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 (see Figs. 2, 5,
10 and 6). 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 43 is disposed
inward (inner diameter side) relative to the annular
15 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 described
later) of the second bearing storing portion 43.
20 [0029] As shown in Figs. 2 and 5, the first bearing
storing portion 42 includes a tubular portion 421 that
holds the outer race side of the first bearing 33 from
the radial direction, an annular flange portion 422
that extends outward (outer circumferential side) in
25 the radial direction of the rotor 3 from one end
portion of the tubular portion 421 in the rotation axis
15
C direction, and a coronal portion 423 that extends
inward (inner circumferential side) in the radial
direction from the other end portion of the tubular
portion 421 in the rotation axis C direction. The
5 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 circumferential
side) in the radial direction of the rotor 3 relative
10 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 of the rotor 3.
[0030] Specifically, the first bearing storing
15 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
magnet portion 31, as viewed from the rotation axis C
direction. Further, the outer circumferential edge
20 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,
in the bracket 41, the outer circumferential edge
25 portion of the flange portion 422 of the first bearing
storing portion 42 is covered with the non-magnetic
16
portion 44 made of resin.
[0031] 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
5 portions (bearing house portions), and the non-magnetic
portion 44 (end surface portion). The first bearing
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
10 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
the rotation axis C direction. This makes it possible
to suppress a leakage flux flowing from the permanent
15 magnet portion 31 to the first bearing storing portion
(magnetic portion) 42. Furthermore, in the first
bearing storing portion (magnetic portion) 42, the
outer circumferential edge portion of the flange
portion 422, which is disposed close to the permanent
20 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
storing portion (bearing house portion) 42 formed of a
25 magnetic substance by the non-magnetic portion 44
formed of a non-magnetic substance, and thus further
17
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
5 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
second bearing storing portion 43 is formed into the
shape similar to that of the first bearing storing
10 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
that extends outward in the radial direction of the
rotor 3 from one end portion of the tubular portion 431
15 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
rotation axis C direction. Additionally, the second
bearing storing portion 43 is disposed on the inner
20 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
covered with the end surface portion 13 (connection
25 portion 14) of the resin motor shell 10 that is a nonmagnetic
substance. This makes it possible to suppress
18
the leakage flux flowing from the permanent magnet 31
to the second bearing storing portion 43.

Claims
[1] An electric motor, comprising:
a main body having a bottomed cylindrical shape
having an opening on one end side;
5 a bracket that covers the opening;
a circuit board disposed in an internal space
surrounded by the main body and the bracket; and
a lead wire connected to the circuit board,
wherein
10 each of the main body and the bracket includes a
lead portion, the lead wire being drawn from the
internal space to an outside through the lead portion,
the lead wire is sandwiched by sandwiching
portions formed in the respective lead portions of the
15 main body and the bracket, and
each of the sandwiching portions includes a
restriction portion that protrudes from at least one of
the main body and the bracket to another one of them.
[2] The electric motor according to claim 1, wherein
20 the restriction portion further includes a
protrusion formed at an edge of the restriction portion
on an inner diameter side, and
the lead wire is bent in the axis direction by the
protrusion.
25 [3] The electric motor according to any one of claims
1 and 2, wherein
47
the sandwiching portion is formed by a first
sandwiching portion and a second sandwiching portion
disposed on an inner diameter side of the main body
relative to the first sandwiching portion, and
5 the restriction portion is provided to the second
sandwiching portion.
[4] The electric motor according to claim 3, wherein
the first sandwiching portion includes
a plurality of abutting portions at which the
10 main body and the bracket abut on each other, and
grooves that are formed between the plurality
of abutting portions in at least one of the main body
and the bracket and pass the lead wire therethrough.
[5] The electric motor according to claim 3 or 4,
15 wherein
each of the main body and the bracket includes an
annular fitting portion that protrudes toward the axis
direction, and
the first sandwiching portion is a part of the
20 fitting portion provided to each of the main body and
the bracket.
[6] The electric motor according to any one of claims
1 to 5, wherein
the main body and the bracket are each formed of
resin.