Abstract: A timing circuit is coupled to control operation of a chiller system in an air conditioner. The timing circuit includes an initial timer to limit to a minimum the amount of coolant initially admitted to an air conditioner compressor upon startup. This drastically lowers the initial amperage demand by the compressor. A chilled water return sensor monitors the temperature of water as it returns to thermal contact with the air conditioner coolant. The return sensor operates a duty cycle timer to intermittently load a line that serves to increase the supply of coolant to the air conditioner compressor. This lowers the average amperage demand of the air conditioning system.

Abstract: An air compressor apparatus including noise-reducing means for converting ambient air into compressed air includes an air compressor surrounded by a noise-reducing enclosure and a plurality of shock-absorbing means disposed between the air compressor and the enclosure. The enclosure includes a pair of interior baffle plates which divide the interior of the enclosure into an air inlet chamber, an air outlet chamber and an air compressor chamber therebetween. The air inlet chamber and the air outlet chamber are each open to the atmosphere at a first lower end and are each in communication with the air compressor chamber at a second opposite upper end. The enclosure further includes a fan positioned within the baffle plate between the air compressor chamber and the air outlet chamber which is operable to draw air in through the open end of the air inlet chamber across the air compressor chamber and out the air outlet chamber.

Abstract: An electronic control system for sequential actuation of a four-way solenoid valve is used to selectively load and unload a slide valve control for a screw compressor. The electronic control system is responsive to output air pressure and pulses a four-way solenoid valve to selectively load and unload the system so that it will maintain system pressure within a preselected deadband. Selective pulsing of the four-way solenoid valve is used to gate hydraulic fluid to load and unload chambers separated by a piston coupled to a slide valve which shifts longitudinally and changes the capacity of the screw compressor. The control system senses output line pressure, and when a limit pressure is exceeded, a dump solenoid valve and fast-unload system is actuated to entirely unload the system of air pressure until reduced to a level below the set deadband. The control circuit also monitors current to the motor which drives the screw compressor.

Abstract: A method in which automatic selection of the mode of operation for a compressor unit is achieved and is dependent on the conditions under which the compressor unit is operated. Depending on the existing compressed air demand and the time sequence thereof, the compressor unit operates in a continuous mode, an intermittent mode, or a regulated mode. During continuous mode operation, the compressor intake is either opened or closed so that the compressor unit operates respectively under zero load, when a minimum pressure condition exists, or full load, when a maximum pressure condition exists. During intermittent mode operation, the compressor unit is turned off when a maximum pressure condition exists and is turned on when a minimum pressure condition exists. During regulated mode operation, the compressor intake is varied between open and closed positions depending on output pressure.

Abstract: A positive displacement gas compressor includes an inlet throttling valve which has an actuator responsive to a pressure fluid signal for closing the throttling valve. A control circuit for supplying pressure fluid to close the throttling valve includes a time delay device and a pilot operated valve which vents the pressure fluid signal holding the throttling valve closed after a predetermined time period commencing with startup of the compressor.

Abstract: A positive displacement rotary compressor is in circuit with a closable chamber disposed upstream of the compressor gas inlet and including a conduit operable to be placed in communication with the compressor discharge conduit. A control circuit is operable to sense compressor discharge pressure and at a predetermined pressure condition sequentially operate valves to shut off compressor inlet flow thereby evacuating the chamber and then placing the compressor discharge port in communication with the chamber. The compressor thereby runs unloaded or at idle at a greatly reduced inlet and discharge pressure. The operation of unloading the compressor may be controlled by sensing the chamber vacuum or by the use of time delay devices.