Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-08-02
2003-02-18
Echols, P. W. (Department: 3726)
Metal working
Method of mechanical manufacture
Electrical device making
C029S598000, C029S602100, C029S606000, C029S607000
Reexamination Certificate
active
06519833
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of magnetizing a permanent magnet motor.
PRIOR ART
An electric motor for driving a refrigerating cycle oriented compressor involves the use of a permanent magnet motor
10
constructed of, as shown in
FIG. 11
, a stator
13
including U-phase stator windings
12
U
a,
12
U
b
wound in multi-layers on, for example, six pieces of pole teeth
11
, V-phase stator windings
12
V
a,
12
V
b
wound thereon and W-phase stator windings
12
W
a,
12
W
b
wound thereon, and a rotor
15
including four pieces of permanent magnets
14
disposed at an angle of 90° in a peripheral direction inwardly of the stator
13
.
The permanent magnet
14
is constructed by incorporating the stator
13
and the rotor
15
and thereafter magnetizing unmagnetized magnet materials provided in four circular arc holes
16
of the rotor
15
by flowing a large direct current through the stator windings.
For attaining this magnetization, as illustrated in
FIG. 12
, a DC power source
17
applies a DC voltage to between two arbitrary-phase winding terminals, e.g., a U-phase winding terminal
12
U and a V-phase winding terminal
12
V, and the direct current flows through the U-phase stator windings
12
U
a,
12
U
b
and the V-phase stator windings
12
V
a,
12
V
b.
With this DC excitation, magnetic fluxes occur in the motor
10
as indicated by arrowheads in FIG.
13
. Forces F attracting each other are produced in the windings through which the direct currents flow in the same direction as produced in the two adjacent-phase windings
12
U
a,
12
V
a
or the windings
12
U
b,
12
V
b
by dint of interaction between those magnetic fluxes and the currents flowing through the windings, with the result that those windings
12
U
a,
12
V
a,
12
U
b,
12
V
b
might be deformed as illustrated in FIG.
14
.
If quantities of these deformations are large, the windings of the phases different from each other come into contact with each other, thereby causing a dielectric breakdown. Besides, a large force is applied to a corner
19
a
of an insulating bobbin
19
wound with the windings and to a proximal portion of a flange, and these portions are flawed. Therefore, those stator windings
12
U
a,
12
U
b,
etc. might undergo a ground fault.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide a method of magnetizing a permanent magnet motor, which is capable of preventing stator windings, an insulating bobbin, etc. from being damaged when forming a permanent magnet by magnetizing an unmagnetized magnet material.
To accomplish the above object, according to one aspect of the present invention, a method of magnetizing a permanent magnet motor comprises a step of preparing an incomplete permanent magnet motor, which is constructed of a stator having stator windings wound in multi-layers on a plurality of magnetic pole teeth of a stator core respectively through an insulating bobbin, and a rotor including unmagnetized magnet material disposed in a rotor core, a step of inserting a spacer in a gap in a slot between the two stator windings wound on the adjacent magnetic teeth, a step of magnetizing the magnet material by electrifying the stator windings with a direct current in a state of the spacer being inserted therebetween, a step of removing the spacer after finishing the step of magnetizing, and thus forming a permanent magnet.
By removing the spacer, space substantially corresponding to the thickness of the spacer is formed between the windings so that the windings are effectively cooled. Further, when the motor according to the present invention is applied to an enclosed compressor, it is possible to flow the emitted coolant from the compressor through the space, thereby the motor windings are effectively cooled and to effectively separate the coolant from the lubricant.
According to the present invention, when magnetizing the unmagnetized magnet material, the stator windings and the insulating bobbin are prevented from being damaged, and it is also feasible to prevent a ground fault and a short-circuit fault of the stator windings.
The spacer may be inserted in between a pair of windings through which at least an electric current flows in the same direction among pairs of windings of adjacent slots.
A required sufficient peripheral thickness of the spacer may be on the order of 70%-110% of the gap between the stator windings.
REFERENCES:
patent: 3727302 (1973-04-01), Phelon
patent: 49-103102 (1974-09-01), None
patent: 63-157646 (1988-06-01), None
patent: 2-110979 (1990-09-01), None
patent: 2-269431 (1990-11-01), None
patent: 3-118749 (1991-05-01), None
patent: 5-50961 (1993-07-01), None
patent: 9-182342 (1997-07-01), None
patent: 9-182388 (1997-07-01), None
patent: 10-126992 (1998-05-01), None
Futami Toshihiko
Inaba Yoshiaki
Kawamura Kiyotaka
Echols P. W.
Foley & Lardner
Toshiba Carrier Corporation
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