Electric motor
First Claim
1. An electric motor comprising a stator assembly including a stator core having a cavity extending therethrough, said cavity having a wall, a rotor assembly, and means for rotatably mounting said rotor assembly in said cavity, a plurality of pairs of coil recesses formed in said wall of said cavity and extending in directions substantially parallel to the axis of said cavity, each pair of said coil recesses defining therebetween a magnetic pole element, a plurality of coil bobbins dimensioned to received in said coil recesses, each of said coil bobbins having wound thereon a selected number of turns of wire to form a pole coil, means for retaining said coil bobbins in said received positions, said rotor being selectively magnetized to have a plurality of magnetic sectors of alternate polarity, a source of direct current operating potential, and commutating means for alternately and sequentially energizing predetermined ones of said pole coils in synchronism with the rotation of said rotor, said commutating means including a solid state switching circuit connected between ground and said pole coils, said switching circuit including a series connected resistor and capacity timing circuit responsive to the self-induced counter voltage in said pole coils for causing said switching circuit to switch in response to the rotational movement and position of said rotor as sensed by said pole coils.
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0 Petitions
Accused Products
Abstract
A direct current electric motor including a stator assembly having a stator core of magnetic material. The core has therethrough a generally cylindrical cavity and rotatably mounted therein is a cylindrical rotor assembly. Recesses are formed in the wall of the cavity, the recesses defining therebetween motor poles. Coil bobbins are provided, the bobbins being dimensioned to be slidably received in the recesses in positions bounding respective ones of the poles and each bobbin having wound thereon a selected plurality of turns of magnet wire. The length of the stator core and rotor assembly and the number of turns can be selectively varied to provide a motor of desired torque. The bobbins may be molded and provided with integrally formed end portions which close the recesses in the wall of the cavity and provide a cavity having a smooth and continuous cylindrical surface. The motor operates from a source of direct current operating potential and may further include electronic commutating means for alternately and sequentially energizing predetermined ones of the coils in synchronism with the rotation of the rotor. The commutating means is responsive to both the rotation and position of the rotor, permits rotation of the rotor in either direction and includes circuitry which minimizes transient voltages applied to the components thereof.
30 Citations
19 Claims
- 1. An electric motor comprising a stator assembly including a stator core having a cavity extending therethrough, said cavity having a wall, a rotor assembly, and means for rotatably mounting said rotor assembly in said cavity, a plurality of pairs of coil recesses formed in said wall of said cavity and extending in directions substantially parallel to the axis of said cavity, each pair of said coil recesses defining therebetween a magnetic pole element, a plurality of coil bobbins dimensioned to received in said coil recesses, each of said coil bobbins having wound thereon a selected number of turns of wire to form a pole coil, means for retaining said coil bobbins in said received positions, said rotor being selectively magnetized to have a plurality of magnetic sectors of alternate polarity, a source of direct current operating potential, and commutating means for alternately and sequentially energizing predetermined ones of said pole coils in synchronism with the rotation of said rotor, said commutating means including a solid state switching circuit connected between ground and said pole coils, said switching circuit including a series connected resistor and capacity timing circuit responsive to the self-induced counter voltage in said pole coils for causing said switching circuit to switch in response to the rotational movement and position of said rotor as sensed by said pole coils.
- 11. An electric motor comprising a stator assembly including a stator core of magnetic material having a cavity extending therethrough, a rotor assembly and means for rotatably mounting said rotor assembly coaxially in said cavity, said stator assembly including a plurality of magnetic poles extending radially inwardly toward the axis of said cavity, each said pole being bounded by a magnetic coil, said rotor being selectively magnetized to have a plurality of magnetic sectors of alternate polarity, a source of direct current operating potential, commutating means for alternately and sequentially energizing predetermined ones of said coils in synchronism with the rotation of said rotor, said commutating means including a solid state switching circuit connected between ground and said coils, said switching circuit including a series connected resistor and capacitor timing circuit and a free-running multi-vibrator having a predetermined free-running frequency, and a biasing circuit coupled to said coils, said biasing circuit being responsive to said counter voltage to cause switching of said multivibrator in synchronism with the rotation and rotational position of said rotor when said rotor is rotating in a clockwise or counter-clockwise direction and at a frequency different from said free-running frequency, said switching circuit including alternately conductive first and second switching elements, each of said switching elements being connected to preselected different ones of said coils, predetermined ones of said coils being energized in response to conductive states of said first and second switching elements, respectively, the electric field generated by said coils in response to the selected energization of alternate ones of said coils being a changing magnetic field, rotational torque being applied to said rotor by said changing magnetic field, said biasing circuit including at least one timing circuit having a predetermined time constant and being coupled to said switching elements and said coils, said free-running frequency being determined by said time constant, said time constant being altered by said counter voltage, said switching elements being first and second transistors, respectively, said transistors having their collector-emitter circuits connected electrically in series with the said predetermined ones of said coils, there being one said timing circuit connected between the collector of said first transistor and the base of said second transistor and including a series connected resistor and capacitor, and a second said timing circuit connected between the collector of said second transistor and the base of said first transistor and including a series connected resistor and capacitor, said first and second transistors being rendered conductive in response to said counter voltage generated in said predetermined ones of said coils connected thereto, respectively, said first and second timing circuits being shunted in response to said conductive states of said second and first transistors, respectively, whereby said frequency of said multivibrator is altered in response to said counter voltage.
- 13. An electric motor comprising a stator assembly including a stator core having a cavity extending therethrough, a rotor assembly and means for rotatably mounting said rotor assembly in said cavity, said stator assembly including a plurality of magnetic poles, said rotor being selectively magnetized to have a plurality of magnetic sectors of alternate polarity, a source of direct current operating potential, commutating means for alternately and sequentially energizing predetermined ones of said poles in synchronism with the rotation of said rotor, said commutating means including a solid state switching circuit connected between ground and said poles, said switching circuit including a series connected resistor and capacitor timing circuit responsive to the self-induced counter voltage in said poles for causing said switching circuit to switch in response to the rotational movement and position of said rotor with respect to said poles.
Specification