Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1989-06-29
1990-12-25
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 80, 310268, 310156, 74 61, 318114, H02K 706, H02K 122, F16H 3314
Patent
active
049805908
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
This invention relates to a flat brushless motor utilizable as a source of vibrations in a portable communication device such as a pocket bell utilizing vibrations to provide an audible signal to a particular person.
BACKGROUND ART
An example of the conventional flat brushless motor of the above described type will be discussed.
FIG. 4 illustrates the conventional flat brushless motor of rotary back-yoke type. Reference numeral 1 represents a flat annular magnet magnetized in a circumferential direction so as to have alternating N- and S-poles; reference numeral 2 represents a rotor frame made of a magnetizable body; reference numeral 3 represents a bracket made of a magnetizable body; reference numeral 3a represents a carrier made of insulating material for holding coils; reference numeral 4 represents a plurality of flat coils fixed to the carrier 3a in face-to-face relationship with the magnet 1; reference numeral 5 represents a back-yoke for enclosing a magnetic circuit of main magnetic fluxes produced by the magnet 1; and reference numeral 6 represents a weight formed into a generally rectangular shape for causing the motor to generate unbalanced vibrations. Reference numeral 7 represents a shaft of the motor; reference numeral 8 represents a metal bearing; and reference numeral 9 represents a rotor boss rigidly mounted on the shaft 7 and to which the rotor frame 2 and the back-yoke 5 are secured.
FIG. 5 illustrates the shape of the weight 6.
FIG. 6 is a perspective view of the conventional flat brushless motor of rotary back-yoke type.
With respect to the conventional flat brushless motor of rotary back-yoke type constructed as hereinabove described, the operation thereof will be described hereinafter.
Assuming that magnetic fluxes are generated from the magnet 1, the magnetic flux developing towards the bracket 3 is shielded by the rotor frame 2 and the bracket 3. Because of this, the main magnetic flux develops in a direction towards the coil 4. If an electric current is allowed to flow across the coils 4 under this condition, a magnetic field is developed by the current and a rotating force is produced by the relationship with the magnetic flux of the magnet 1. Also, a magnetic circuit is formed by the magnetic flux towards the back-yoke 5 to thereby increase the efficiency. The weight 6 is fixed to the shaft 7 with its center of gravity displaced from the shaft so that the weight 6 is in an unbalanced relationship with the shaft 7 to allow the motor to produce an unbalanced rotation when the weight 6 is driven to produce vibrations.
However, in the conventional construction, since a portion corresponding to the weight 6 increases the thickness of the motor, there are some problems in that flattening of the motor, is hampered and the number of manufacturing steps as well as the number of component parts is increased. Accordingly, the present invention has for its object to provide a flat brushless motor of a thin type capable of generating vibrations. Also, the present invention has for its object to provide a flat brushless motor capable of, reducing the number of component parts and the number of manufacturing steps.
DISCLOSURE OF THE INVENTION
In order to accomplish these objects, the present invention is constructed so as to have a back-yoke with no weight used and of which the center of gravity is moved to a position other than the center of rotation. Accordingly, by the rotation of the unbalance back-yoke, vibrations are generated and, also, by the elimination of the weight, it can be possible to flatten the motor, and to, reduce the number of component parts, the number of manufacturing steps and the cost.
Also, the present invention has the following relationship: (mm) represents the displacement of the center of gravity relative to the center of rotation of the back-yoke. Because of this, the extent can be established so that vibrations resulting from the displacement of the center of gravity of the back-yoke can be assuredly transmitted to the user. Also, the p
REFERENCES:
patent: 4361776 (1982-11-01), Hayashi et al.
patent: 4644246 (1987-02-01), Knapen
Furuya Miyuki
Hasegawa Makoto
Taniguchi Shinobu
LaBalle C.
Matsushita Electric - Industrial Co., Ltd.
Stephan Steven L.
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