Motor driven air compressor having a combined vent valve and check valve assembly

摘要

An air compressor driven by a permanent split capacitor electric motor of the type having substantially the same value capacitance for starting as for operating and which has insufficient starting torque for starting when the air compressor is loaded with pressurized air. The pressurized air output from the air compressor is delivered through an air line to a compressed air storage tank. A check valve between the air line and the tank permits air flow from the air line to the tank while preventing a reverse air flow. A vent valve is connected to vent air pressure from the air line when the motor is stopped to unload the air compressor. When the motor is restarted, closure of the vent valve is delayed until the output torque from the motor exceeds the torque requirements of the compressor when loaded. Vent valve closure may be delayed for a predetermined me or until the motor reaches a predetermined high operating speed or until the air flow from the unloaded air compressor reaches a predetermined level.