Importance

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Abstract

A liquid fogging apparatus has a motor which operates from the 12 volt power supply of a vehicle and delivers high torque at high speed, operating aproximately at 0.2 horsepower at 28,000 RPM. A rotating ring of porous ceramic material atomizes the liquid. The motor is small, 1.6' in diameter with a 5/8' diameter rotor. The stator has four phases each preferably containing eight three-turn windings of four strand wire, wound in slots in the outer surface of a short laminated stack, which is reinforced in epoxy with its inner surface honed to minimum thickness to reduce flux leakage. Eight bipolar permanent magnets are set in axial slots of a rotor stack with like poles facing tangentially toward each other around the rotor shaft. A controller commutates the motor sensing back-EMF on the windings to control speed and detect motion during start-up. Start-up is accomplished with a fixed frequency external oscillator which sequentially energizes the coils, followed by DC commutation until the motor accelerates, then pulse-width control of operating speed. The motor drops to an idle speed when the load is removed. An inhibit signal disables the fogger pump if motor speed is too low.

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First Claim