Miniature D.C. motor provided with rotation detector
AssigneeMabuchi Motor Co., Ltd.
InventorNobuyuki Sata
Life of this patent
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Abstract
A miniature D.C. motor has a casing in which magnets are disposed and a rotor is disposed inside the magnets. The rotating condition is detected by a rotation detector which comprises an inductor and a capacitor. The inductor detects leaking fluxes externally from the casing among fluxes created by mutual operations of the magnets and an armature and converts a change of the leaking fluxes into electric signals. The capacitor is electrically connected to the inductor so as to constitute a resonance circuit. The resonance circuit is mounted on an outer surface of the casing. A resonance frequency of the resonance circuit is made so as to correspond to a frequency to be generated for a rotating time of the armature.
Claims23
A miniature D.C. motor, comprising:
- a casing in which a magnet means is disposed, said casing having an end portion with a protruded portion;
- a rotor having a rotation shaft and disposed inside the magnet means to be rotatable, and
- a rotation detector detecting a rotation condition of the rotor, wherein said rotation detector comprises:
- a rotation detector casing;
- an inductor means for detecting magnetic fluxes leaking externally from the casing among the magnetic fluxes created by mutual operations of the magnet means and an armature of the rotor and for converting a change of the leaking magnetic fluxes into electric signals, and
- a capacitor means electrically connected to the inductor means so as to constitute a resonance circuit means, said resonance circuit means being mounted on an outer surface of the casing,
- wherein a resonance frequency of the resonance circuit means is made so as to correspond to a value of a frequency to be generated for a rotating time of the armature, and
- wherein said rotation detector casing has a bottom plate formed with a recessed portion for accommodating therein said protruded portion of said casing of said motor.
A miniature D.C. motor, comprising:
- a casing in which a magnet means is disposed, said magnet means being composed of a pair of permanent magnets mounted on an inner peripheral surface of the casing, each of said permanent magnets being formed in an arc segment shape and being formed out of a magnetic material such as hard ferrite;
- a rotor having a rotation shaft and disposed inside the magnet means to be rotatable;
- and
- a rotation detector detecting a rotation condition of the rotor, wherein said rotation detector comprises:
- an inductor means for detecting magnetic fluxes leaking externally from the casing among the magnetic fluxes created by mutual operations of the magnet means and an armature of the rotor and for converting a change of the leaking magnetic fluxes into electrical signals, and
- a capacitor means electrically connected to the inductor means so as to constitute a resonance circuit means, said resonance circuit means being mounted on an outer surface of the casing,
- wherein a resonance frequency of the resonance circuit means is made so as to correspond to a value of a frequency to be generated for a rotating time of the armature,
- wherein a center of said inductor means is arranged in a 90.degree.-angled position in a case where one direction of a central line connecting centers of the respective permanent magnets is a 0.degree.-angled position and another direction normal to the one direction is a 90.degree.-angled position, and
- wherein the inductor means includes a ferrite core which is directed to a direction parallel to the central line connecting the centers of the permanent magnets.
Dependencies are inferred from the claim text.