Motor

Details Motor Motor

2003-12-03

2004-12-28

Le, Dang (Department: 2834)

Electrical generator or motor structure

Dynamoelectric

Rotary

C310S051000

Reexamination Certificate

active

06836051

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a concentrated winding motor that is highly efficient and capable of reducing vibration and noise, and an apparatus loaded with the concentrated winding motor, which is highly efficient with low noise and less vibration, such as a hermetically enclosed compressor, a refrigerating apparatus (a refrigerator, a freezer, an ice making machine, a showcase, a vending machine), an air conditioner (an air-conditioner, a dehumidifier) or an electronic circuit cooling system, or a car actuator and an automobile or the like loaded with this car actuator.
BACKGROUND OF THE INVENTION
Conventionally, concentrated winding motors generally used in a compressors and the like of air conditioners and refrigerators are each composed of a stator
40
and a rotor
50
as shown in FIG.
8
.
The stator
40
has teeth
42
provided at a stator core
41
, and slots
43
. Three-phase winding wires
44
U,
44
V and
44
W are provided to the teeth
42
with an insulating material (an insulating film, an insulator or the like: not shown) between the wires and the stator core
41
.
The stator core
41
faces an outer circumference of the rotor
50
, and has teeth tip end broad portions
45
usually placed to be wide at tip ends of the teeth
42
, a substantially annular yoke
46
for connecting the respective teeth, and through-holes
47
in an outer circumference of the stator core
41
.
The through-hole
47
is formed between a housing
61
and the stator core
41
when the stator
40
is shrinkage-fitted into the compressor housing
61
of a hermetically enclosed compressor, and serves as a passage for a refrigerant (for example, see Japanese Unexamined Patent Publication No. 2001-78375).
Alternatively, through-holes are provided in an outer circumferential part of the stator core in some cases (see Japanese Unexamined Patent Publication No. 62-147924).
The winding wires are of three phases of U, V and W phases, and sine wave drive and rectangular wave drive are performed by controlling applied voltage with an inverter.
The rotor
50
is rotatably held concentrically with the stator
40
inside the stator
40
, and a rotor core
51
in
FIG. 8
represents an embedded magnet type rotor in which permanent magnets
52
are embedded.
End plates (not shown) are mounted to both ends of the rotor core
51
, and they are fixed by caulking after inserting rivets (not shown) through a through hole provided in the rotor core
51
. A shaft is inserted into a shaft hole
53
.
The rotor
50
rotates around the shaft by rotating force of a sum of magnet torque and reluctance torque by a rotating magnetic field by an electric current passing through the winding wires
44
U,
44
V and
44
W applied to the stator
40
.
In the above-described conventional concentrated winding motor, magnetic flux intensively flows into the aforesaid teeth
42
in its structure, and therefore a radial force (the force in a radius direction) to deform the stator
40
tends to be large.
Especially in a motor driven by rectangular wave voltage or a rectangular wave current, an electric current always passes through only two phases out of the three phase winding wires applied to the teeth
42
, and therefore magnetic flux concentrates on two teeth
42
per pole pair, which imbalances the radial force and causes elliptical vibration more easily as compared with distributed winding, thus further increasing vibration and noise of the motor.
In the prior art, notches (the through-holes
47
in
FIG. 8
) are provided at the yoke
46
located on outer circumferential sides of the teeth
42
to prevent contact with the housing
61
, so that the vibration by the radial force concentrated on the teeth
42
is not directly transmitted to the housing
61
, and thus the vibration of the motor is suppressed. However, in this case, the vibration of the teeth
42
adjacent to each other causes the yoke
46
to vibrate, and the noise of the motor cannot be prevented from increasing, either.
Moreover, in the case in which the stator
40
is shrinkage-fitted into the housing
61
, stress from the housing
61
is applied to the yoke
46
, and therefore there arises the problem that iron loss increases. However, to ensure reliability of the motor, holding force of the stator core
41
and the housing
61
has to be kept, and therefore it is necessary to bring the yoke
46
and the housing
61
in close contact with each other.
DISCLOSURE OF THE INVENTION
In view of the aforesaid conventional problems, the present invention has its object to provide a motor that reduces vibration and noise by suppressing the vibration transmitted from a stator to a housing, and an apparatus loaded with the motor, which is highly efficient with less vibration and low noise.
In order to solve the above-described problems, in the present invention, notches are provided in an outer circumference of a yoke adjacent to outer peripheries of slots, so that the notches do not contact the housing, the yoke located adjacent outer peripheries of teeth is provided with axially penetrating through-holes, and an outer circumference of the stator core located adjacent outer peripheries of the through-holes is in close contact with the housing. Thus, it becomes possible to obtain the motor with high efficiency, less vibration and low noise.
A motor according to the first aspect of the present invention is a motor comprising: a stator having an annular yoke, a plurality of teeth disposed at an inner circumferential portion of the yoke and a stator core formed with slots between the plurality of teeth, with three-phase concentrated winding wires provided to the teeth; and a rotor rotatably held in an opposed relation to an inner circumference of the stator via a small clearance, and provided with permanent magnets inside or on a surface of the rotor core. The stator core has an outer circumference being partly in close contact with and held by a housing. The motor is characterized in that the yoke located adjacent to outer circumferences of the teeth is provided with axially penetrating through-holes, and the outer circumference of the stator core located adjacent to outer circumferences of the through-holes is in close contact with the housing. Consequently, radial force applied to the teeth is distributed by the through-holes and is restrained from being transmitted to the housing. In addition to this, the outer circumference of the stator core located adjacent to the outer circumferences of the through holes is in close contact with the housing, whereby holding force of the stator core and the housing can be sufficiently kept, and therefore the highly reliable motor with less vibration and low noise can be obtained.
A motor according to the second aspect of the present invention is a motor comprising: a stator having an annular yoke, a plurality of teeth disposed at an inner circumferential portion of the yoke and stator core formed with slots between the plurality of teeth, with three-phase concentrated winding wires provided to the teeth; and a rotor rotatably held in an opposed relation to an inner circumference of the stator via a small clearance, and provided with permanent magnets inside or on a surface of the rotor core. The stator core has an outer circumference being partly in close contact with and held by a housing. The motor is characterized in that a notch is formed in an outer circumference of the yoke located adjacent to an outer periphery of the slot so that the outer circumference of the stator core does not contact the housing in the notch. Consequently, the vibration is not transmitted to the housing from the notch, and stress is not applied to the yoke, whereby iron loss is reduced, vibration and noise of the motor are reduced, and in addition, high efficiency can be realized.
A motor according to the third aspect of the present invention is a motor comprising: a stator having an annular yoke, a plurality of teeth disposed at an inner circumferential portion of the yoke and a stator core formed with slots between the plur

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