Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-07-21
2001-05-01
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S261100
Reexamination Certificate
active
06225724
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor having a rotor embedded with permanent magnets and a method of manufacturing the motor.
2. Discussion of Background
When permanent magnets of a sintered type are embedded in a motor, the motor is manufactured by inserting permanent magnets into slits formed in a rotor core and filling the gaps caused by errors in their form by a filler and/or a bonding agent and then fixing the permanent magnets to the rotor core by mechanically joining the permanent magnets to the rotor core using joining methods like bolts and nuts, methods have obstructive factors in forming the permanent magnets which reduce productivity of the motor assembly. Further, in the case where the permanent magnets are formed by injecting a powdered material constituting permanent magnets, it is necessary to introduce a rotor under a high temperature of 500° C. or more for a long period, which requires expensive equipment and reduces reliability due to residual stress and deformation caused by the application of heat to the rotor, and so on.
FIG. 14
is disclosed in JP-A-10-112946 to solve the above-mentioned problems, wherein a structure of rotor of a brush-less d.c. motor with embedded permanent magnets is shown. In
FIG. 14
, permanent magnets formed by bonding magnetic powders having a hard magnetic phase and a resin with a soft magnetic phase are inserted in slots
2
formed at four positions in a rotor core
1
; and thereafter the permanent magnets are fixed to the rotor core
1
by adhering or mechanically joining using bolts and nuts.
However, failures caused by peeling-off, cutout, and so on occurred to the permanent magnets during high revolutions for a long period even though such joining methods were used.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above-mentioned problems inherent in the conventional technique and to provide a motor embedded with permanent magnets which can be manufactured by shortening the time for forming permanent magnets while increasing productivity.
According to a first aspect of the present invention, there is provided a motor embedded with permanent magnets which is integrally formed by directly injecting bond magnets made of a resin having dispersed powders of permanent magnet material into slits, respectively provided in each of various poles of a rotor core, and by curing the bond magnets. This removes the need for using a bonding agent or a filler and fixing of the permanent magnets using mechanically binding means such as bolts and nuts.
According to a second aspect of the present invention, there is provided the motor embedded with permanent magnets, wherein the resin forming the bond magnets is a thermoplastic resin.
According to a third aspect of the present invention, there is provided the motor embedded with permanent magnets, wherein the resin forming the bond magnets is a thermoset resin.
According to a fourth aspect of the present invention, there is provided the motor embedded with permanent magnets, wherein a rotor is composed of a plurality of rotor blocks piled in its axial direction, the rotor blocks respectively formed by laminating a plurality of rotor core plates.
According to a fifth aspect of the present invention, there is provided the motor embedded with permanent magnets, wherein the rotor blocks have spacers formed thereon being made of thin layers of the bond magnets having shapes of recesses and projections, complementary each other, respectively on surfaces in the axial direction of the rotor blocks; and the rotor blocks are piled so that the recesses and projections of adjoining spacers of the rotor blocks are engaged with each other.
According to a sixth aspect of the present invention, there is provided a method of manufacturing a motor embedded with permanent magnets comprising steps of: injecting bond magnets, made of a thermoplastic resin including dispersed powders of permanent magnets material having a melt flow rate of 0.3 or more under test conditions of a temperature of 300° C., a load of 20 kg-f, an inner diameter of die of 1.0 mm, and a thickness of die of 1.0 mm in conformity with a definition of JISK7210, into slits respectively provided in each of poles of rotor core by heating and fluidizing the bond magnets, and curing the bond magnets.
According to a seventh aspect of the present invention, there is provided a method of manufacturing a motor embedded with permanent magnets comprising steps of: injecting bond magnets, made of a thermoset resin including dispersed powders of permanent magnets material having a viscosity of 1,000 through 10,000 cP, into slits respectively provided in each of poles of rotor core, and curing the bond magnets.
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Daikoku Akihiro
Nakahara Yuji
Ohshige Toyomi
Toide Yukari
Ugai Yoshikazu
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
Nguyen Tran
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