US 4,467,257 AGranted

Multiple speed induction motor

AssigneeA. O. Smith Corporation

InventorsRobert H. Douthart, Howard W. Smith

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Abstract

An AC induction motor has a two-pole run winding connected directly to power, a four-pole run winding connected to power by a "Triac" switch, and a separate start winding connected to power by a "Triac" switch and a centrifugal start switch. The centrifugal switch is connected between a common node to the start "Triac" and either one or the other of the power terminals. The motor always starts as a two-pole start and two-pole run winding motor. Depending upon the power terminal connection, the motor continues to run with power supplied to the two-pole run winding, or actuate the "Triac" switch of the four-pole winding to operate as a four-pole motor. In different embodiments, the centrifugal switch is connected between the start circuit terminal and either the power terminal of the four-pole winding or of the two-pole winding.

Claims19

Dependent claims

A multiple speed motor comprising a first speed winding means, a second speed winding means, a start winding means, three power terminals including a first power terminal connected to the first speed winding and a second power terminal connected to the second speed winding and a common power terminal connected to said first and second speed windings, first and second separate switch means for said start winding means and for the second of said first and second speed winding means, a speed responsive switch means, circuit means connecting said start winding means to said common power terminal and to one of said first and second power terminals and connecting said start winding means to the other of said first and second power terminals in series with said speed responsive switch means, and said separate switch means and said speed responsive switch means being constructed and connected to conjointly operate to simultaneously energize said first speed winding and said start winding during an initial start period and at selected speed operable to de-energize said start winding and to energize only one of said first speed winding and said second speed winding in accordance with the power connection to said first and second power terminals.

A multiple speed motor comprising a first non-switched speed winding having a first number of poles, a second switched speed winding having a different number of poles, a start winding, a start capacitor, a common power terminal connected to said first and second speed windings, a first speed terminal connected directly to the first non-switched speed winding, a second speed terminal, said first and second speed terminals being adapted to be connected to one side of a power supply with said common terminal connected to the second side of power supply, a solid state gated run switch connecting said second switched speed winding to said second speed terminal and having a gate means, a gated start switch means having a gate means coupled to the first speed winding, a start branch circuit including series connection of said start winding with said start capacitor and said gated start switch means, a speed responsive switch connected between said first and second power terminals, said start branch circuit having one connection to a common node between said speed responsive switch and one of said power terminals, said gate means of said solid state gated run switch being connected to said start branch circuit and energized in response to operation of said speed responsive switch to condition said switched speed winding for operation, said start switch means with said speed responsive switch means being conjointly operable to simultaneously energize said first speed winding and said start winding during an initial start period independent of connection to which of said first and second power terminals are connected to said power supply and at a selected speed operable to open the circuit from the one power terminal to said start winding and to selectively connect said first speed winding to establish a first speed mode of operation and said second speed winding to establish a second speed mode of operation in accordance with which of said first and second power terminals is connected to power supply.

Dependencies are inferred from the claim text.