Abstract: A variable speed drive motor system is disclosed. The motor system is particularly suitable for use as a drive system for a centrifugal compressor in a refrigeration system. The motor system includes an AC auxiliary motor/generator with inverter control. The motor/generator is interconnected through a transmission system to a main motor to drive an output drive shaft at varying speeds. Preferably, the interconnecting transmission system is an epicyclic gear system.

Abstract: A method and apparatus to prevent oil pump cavitation in a hermetically sealed vapor compression refrigeration system are disclosed. A hermetically sealed housing containing the refrigeration compressor transmission and oil supply reservoir is connected to the suction side of the compressor to equalize the pressure in the housing and the suction to the compressor is constructed with a restriction such as an orifice or a venturi to create a pressure drop or is of a size small enough to create a pressure drop when refrigerant flows through the line. The pressure drop is sensed by a pressure differential switch to anticipate sharp drops in pressure in the housing. The flow of refrigerant to the compressor is throttled in response to predetermined pressure drops to prevent a sharp drop in pressure within the transmission housing and thus prevent vigorous boiling of refrigerant from the oil reservoir.

Abstract: Apparatus for satisfying heating and cooling demands including a cooling circuit having a high pressure side and a low pressure side, and a heating circuit including a booster compressor for drawing and compressing refrigerant from the high pressure side of the cooling circuit. Also disclosed is a sensor for sensing the temperature of vapor discharged from the booster compressor, and a control responsive to the sensor for terminating the heating action of the heating circuit when the temperature of vapor discharged from the booster compressor exceeds a preset value.

Abstract: A purge system for use in a refrigeration system utilizing more than one condenser, each of which operates at different pressures. The purge system includes a purge chamber having a cooling coil connected to the evaporator and adapted to condense refrigerant vapor. The purge chamber is connected to a main purge refrigerant line which includes a pressure reducing device. Either condenser in the refrigeration system is provided with a secondary purge refrigerant line connected to the main purge refrigerant line and having a one-way valve to prevent refrigerant flow from one condenser to another condenser. A pump is mounted in the system to remove the non-condensibles from the purge system. The pump is operatively connected to a pressure switch arranged between two sampling pressure lines, one of which is extending to the purge chamber and another one is extending to the main purge refrigerant line at a point ahead of the pressure reducing device.

Abstract: Apparatus for satisfying heating and cooling demands including a cooling circuit including a mechanical refrigeration unit having a low pressure side and a high pressure side, a heating circuit including a booster compressor for drawing and further compressing refrigerant from the high pressure side of the refrigeration unit, and a heat reclaiming condenser for passing the further compressed refrigerant vapor in heat transfer relation with a heat transfer fluid to heat the fluid and condense the refrigerant vapor. Also disclosed is a control for reducing the vapor flow rate through the booster compressor when the pressure in the high pressure side of the refrigeration unit falls below a predetermined value.