Automotive alternator having detector for detecting initiation of rotation
First Claim
1. An automotive alternator, comprising:
- a rotor having a plurality of field poles;
a field winding for magnetizing the field poles;
an armature for generating alternating voltage induced by a rotating field of the rotor, the armature including three-phase windings;
a rectifier for rectifying the alternating voltage into a direct current voltage, the rectifier including at least one negative-side diode;
a voltage regulator including a resistor for detecting a low voltage induced in one of the three-phase windings by residual magnetism in the field poles, the resistor being connected to the one of the three-phase windings; and
a capacitor connected between another one of the three-phase windings and a negative terminal of the rectifier, wherein the voltage regulator detects initiation of rotation of the rotor based on a voltage across the resistor thereby to start excitation current supply to the field winding, and thereafter controls the excitation current to control an output voltage of the alternator.
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Accused Products
Abstract
An alternator for use in an automotive vehicle includes a circuit for detecting initiation of rotation of an engine. Upon detecting the initiation of rotation, excitation current supply to a field winding is started, and thereafter an alternator output is controlled by controlling the excitation current. A resistor is connected to one phase winding of an armature to obtain a voltage indicating initiation of rotation during a period in which no excitation current is supplied to the field winding, and a capacitor is connected to another phase winding to raise the indicating voltage level. Since the indicating voltage induced by a small amount of residual magnetism is increased to a sufficient level by the capacitor, the initiation of rotation can be accurately detected.
39 Citations
5 Claims
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1. An automotive alternator, comprising:
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a rotor having a plurality of field poles;
a field winding for magnetizing the field poles;
an armature for generating alternating voltage induced by a rotating field of the rotor, the armature including three-phase windings;
a rectifier for rectifying the alternating voltage into a direct current voltage, the rectifier including at least one negative-side diode;
a voltage regulator including a resistor for detecting a low voltage induced in one of the three-phase windings by residual magnetism in the field poles, the resistor being connected to the one of the three-phase windings; and
a capacitor connected between another one of the three-phase windings and a negative terminal of the rectifier, wherein the voltage regulator detects initiation of rotation of the rotor based on a voltage across the resistor thereby to start excitation current supply to the field winding, and thereafter controls the excitation current to control an output voltage of the alternator. - View Dependent Claims (2, 3, 4, 5)
the voltage regulator determines that rotation of the rotor is initiated when the voltage across the resistor is higher than a predetermined level and a frequency of the voltage exceeds a predetermined frequency.
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3. The automotive alternator as in claim 1, wherein:
an impedance of the capacitor in a basic frequency region corresponding to an idling speed of an automotive engine is set to a level lower than a resistance of the resistor.
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4. The automotive alternator as in claim 2, wherein:
an impedance of the capacitor in a basic frequency region corresponding to an idling speed of an automotive engine is set to a level lower than a resistance of the resistor.
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5. The automotive alternator as in claim 1, wherein:
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the voltage regulator is composed of Zener diodes; and
an impedance of the capacitor is set to such a level that the voltage appearing across the resistor at a maximum rotational speed of the rotor under a situation where no exciting current is supplied to the field winding becomes lower than a Zener voltage of the Zener diodes.
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Specification