US Patent 6877314 Stirling motor and heat pump

Stirling engine which may be used as a heat pump, which consists of a hot half and a cold half. Both halves are connected by two lines which constitute a counterflow heat exahnger or in which a counterflow heat exchanger is mounted. Moreover, a mutual shaft, to which in the hot half a large and a small piston are mounted and to which in the cold half a large and a small piston are mounted, connects both parts. For every up or down going movement of the shaft, a complete Stirling cycle is performed. If desired, the shaft may be replaced by a hydraulic interconnection.