Air temperature control system

Claim 1

An air temperature control system for individually controlling the air temperature of each of a plurality of rooms comprising at least one selectively operable air vent in each of said rooms connected to the mouth of a preexisting air duct providing a supply of air at a controlled temperature into each of said rooms respectively, thermostat means for sensing the air temperature in each of said rooms and for providing a first signal when the air temperature exceeds a first preselected temperature level and a second signal when said air temperature drops below a second preselected temperature level, and drive means comprising a continuously energized reversible electric motor operative in response to said first and second signals to selectively open and close said vents thereby controlling the flow of said temperature controlled air supply through said ducts into said rooms respectively to thereby maintain the air temperature in each of said rooms in the range between said first and second temperature levels, said motor including a rotor, main field winding means producing a continuous torque on said motor in one direction and a pair of shading coils producing a continuous torque greater than said main field winding torque on said rotor in a direction opposite to said one direction to produce a continuous net torque on said rotor in said opposite direction, means for applying said continuous net torque on said rotor to said air vent, and mechanical stop means to limit the travel of said air vent in response to the application thereto of said continuous net torque.