Easily restarted brushless DC motor
First Claim
1. A brushless motor comprising a stator core, a rotor having permanent magnets disposed around a rotor core of said rotor, a stator coil providing magnetic flux for exciting said rotor, a rotational position sensor for detecting a rotational position of said rotor, and a controller for controlling polarity of electrical power supplied to said stator coil in accordance with an output from said position sensor, wherein:
- (i) said stator core is made of a plurality of laminated electrical steel sheets, each of said electrical steel sheets having a substantially round aperture and being disposed around said aperture such that a closed magnetic circuit is formed around said aperture and such that a bore for receiving said rotor is formed by said aperture when said plurality of electrical steel sheets are laminated;
(ii) said stator coil is composed of single coil with a pair of terminals, said stator coil being mounted on one side of said bore of the stator core;
(iii) said rotational sensor is composed of a single magnetic, non-mechanical sensor which is disposed on said stator core adjacent to an outer surface of said rotor;
(iv) the polarity of the electrical power of said stator coil is alternately switched over by said controller; and
(v) said bore of said stator core has a shape such that a continual air gap is formed between a wall of said bore and an outer surface of said rotor, said air gap having portions containing a large gap and portions containing a small gap arranged alternately on a circumferential surface of said bore.
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Accused Products
Abstract
An easily restarted brushless DC motor has a skeleton type stator core, a rotor core having permanent magnets arranged around it, and needs only one position sensor adapted to detect a rotational position of a rotor and only one stator coil. A controller is provided for switching over the polarity of the electrical power supplied to the stator coil in accordance with an output of the position sensor.
62 Citations
6 Claims
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1. A brushless motor comprising a stator core, a rotor having permanent magnets disposed around a rotor core of said rotor, a stator coil providing magnetic flux for exciting said rotor, a rotational position sensor for detecting a rotational position of said rotor, and a controller for controlling polarity of electrical power supplied to said stator coil in accordance with an output from said position sensor, wherein:
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(i) said stator core is made of a plurality of laminated electrical steel sheets, each of said electrical steel sheets having a substantially round aperture and being disposed around said aperture such that a closed magnetic circuit is formed around said aperture and such that a bore for receiving said rotor is formed by said aperture when said plurality of electrical steel sheets are laminated; (ii) said stator coil is composed of single coil with a pair of terminals, said stator coil being mounted on one side of said bore of the stator core; (iii) said rotational sensor is composed of a single magnetic, non-mechanical sensor which is disposed on said stator core adjacent to an outer surface of said rotor; (iv) the polarity of the electrical power of said stator coil is alternately switched over by said controller; and (v) said bore of said stator core has a shape such that a continual air gap is formed between a wall of said bore and an outer surface of said rotor, said air gap having portions containing a large gap and portions containing a small gap arranged alternately on a circumferential surface of said bore. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification