Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-06-07
2001-08-21
Nguyen, Ngoc-Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S06700R
Reexamination Certificate
active
06278216
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a vehicle motor, and more particularly to a brushless motor for use in a motor bicycle which minimizes vibration and cogging torque during rotary motion of the rotor.
(b) Description of the Prior Art
Regular bicycles are used as sports equipment or short distance transportation vehicle means. Because riding a bicycle consumes much effort, a bicycle is not suitable for use as a long distance transportation vehicle. In recent years, various motor bicycles have been developed for use as practical transportation vehicle means. U.S. Pat. No. 5,581,136 teaches the use of a vehicle motor in a bicycle. Various brushless motors have been disclosed for use in motor bicycles. However, these brushless motors, still do not satisfactorily function because they cannot eliminate a cogging torque. These brushless motors commonly comprise a stator and a rotor. The rotor comprises a plurality of equiangularly spaced magnets. The stator is comprised of a silicon steel stack having a plurality of T-teeth around the periphery, and a winding mounted on the T-teeth. The number of the T-teeth is a common multiple of the number of the magnets at the rotor, or equal to the number of the magnets. When one magnetic pole of the rotor is aligned with the center of the magnetic field of one magnetic pole of the winding at the stator, a dead angle is produced, causing the rotor to vibrate. For example, if the number of T-teeth of the stator of a two-phase motor is
4
, the rotor has N pole and S pole, and a dead angle is produced when upon each 90° rotation of the rotor. If the number of T-teeth of the stator of a three-phase motor is a common multiple of or equal to the number of the magnets at the rotor of the rotor, a cogging torque will be produced when starting the rotor. This drawback shortens the service life of the motor, and affects the performance of the motor. During operation of the motor, high heat may be produced, causing the related Hall ICs to be burned out.
SUMMARY OF THE INVENTION
The present invention provides a vehicle motor for a motor bicycle which eliminates the aforesaid problems. According to one aspect of the present invention, the rotor and the stator are well matched to eliminate a cogging torque during rotary motion of the rotor relative to the stator, so that neither starting dead angle nor noise are produced during the operation of the motor. According to another aspect of the present invention, a Hall IC set is provided having three Hall ICs mounted on a circuit board for direction change detection, and disposed at the best position to match with a three-phase winding, so as to minimize power consumption. According to still another aspect of the present invention, a thermal control IC is installed in one of the three electric wires of the three phase winding to protect the motor. The thermal control IC automatically cuts off power supply from the motor when the temperature of the motor surpasses a predetermined value, or returns the supply of electric power to the motor when the temperature of the motor drops below predetermined value. The operation of the thermal control IC prevents the Hall ICs from being burned out, and the insulator of the electric wires from being damaged by heat. The operation of the thermal control IC also prevents a loss of magnetic force.
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Bacon & Thomas PLLC
Nguyen Ngoc-Tran
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