Abstract: A thermal machine that can function as either a refrigerator or an external combustion heat engine is disclosed. A working gas undergoes four thermodynamic processes that comprise a Brayton cycle. Two of these processes, adiabatic compression and adiabatic expansion, take place in the same cylinder, within which a piston, driven by a crankshaft, reciprocates. The remaining two processes, each of which is a transfer of heat at constant pressure, take place in a high pressure heat exchanger and a low pressure heat exchanger. A rotary valve, rotating at one-half crankshaft speed, creates passages between the cylinder and the heat exchangers, and is constructed so that compression and expansion ratios are equal.

Abstract: A Triac and a phase-locked loop are used to control the amplitude of reciprocation of an AC linear motor. The phase locked loop generates a square wave that is synchronized with an AC power source but is substantially isolated from electrical noise on the power source. The phase of the square wave is varied with an amplitude control signal, and Triac firing pulses are generated at the transitions of the square wave.

Abstract: Disclosed is a method of generating magnetic centering force on the permanent magnets of a reciprocating permanent magnet motor or generator, by allowing the ferromagnetic structure of the machine to saturate magnetically when the permanent magnets are near the ends of their travel.

Abstract: Disclosed is a method of generating magnetic centering force on the permanent magnets of a reciprocating permanent magnet motor or generator, by allowing the ferromagnetic structure of the machine to saturate magnetically when the permanent magnets are near the ends of their travel.

Abstract: A refrigerator that efficiently cools multiple cold spaces at different temperatures with one compressor and one condenser is disclosed. Multiple, fan equipped evaporators are in series, and an expansion valve regulates superheat from inlet to outlet of the series evaporators. Cold space temperatures are regulated with an on-off thermostat in each space. If only one fan is turned on, system performance approaches that of a single evaporator refrigerator with controlled superheat. More than one evaporator fan may be turned on for initial cooldown.

Abstract: In a vapor compression refrigerator with closed loop feedback control of evaporator superheat, a superheat stabilizer consisting of a cavity connected between the evaporator outlet and the suction line inlet, the cavity combining the functions of liquid separation and vapor superheating in order to stabilize superheat by preventing liquid from reaching the outlet vapor temperature sensor and also by achieving preset superheat downstream of the evaporator.

Abstract: Circuits for converting DC voltage into controllably variable amplitude AC voltage, for the purpose of driving an oscillating linear motor with controllable amplitude, are disclosed. Unlike pulse width modulation circuits for the same purpose, the disclosed circuits do not require suppression of electromagnetic interference and have negligible switching loss.

Abstract: Disclosed is a reed valve which uses a simple electromechanical actuator to apply a force that overcomes pressure force and opens the valve. The valve is closed by pressure and the elastic restoring force of the reed. Two of the disclosed valves in a back-to-back connection accommodate bi-directional flow. The disclosed valve is especially suited for application as a pulsed expansion valve for refrigerators and heat pumps.