US Patent 7458216 Exhaust heat recovery apparatus

An exhaust heat recovery apparatus (functioning as a Stirling engine), which is installed in, for example, an exhaust passage of an internal combustion engine and an exhaust passage of factory exhaust heat as restraining reduction in exhaust heat recovery efficiency, is installed in a device installing surface formed in the heat medium passage so that the device installing surface and a heater connecting side end surface of a high temperature side cylinder become parallel and the device installing surface and a cooler connecting side end surface of a low temperature side cylinder become parallel. The high temperature side cylinder is arranged at an upstream side of a direction of exhaust flow. The low temperature side cylinder is arranged at a downstream side of the high temperature side cylinder.