Abstract: A method for controlling the fuel-air ratio of a burner having a blower responsive to a blower drive signal for injecting air into the burner. The method is based at least on the concentration of a gas in an exhaust gas product of a combustion chamber of the burner and includes measuring the gas concentration in the exhaust gas product, deriving a gas concentration signal from the measured gas concentration, determining the fuel-air ratio from the gas concentration signal and the sign of the derivative of the gas concentration signal with respect to the blower drive signal, and controlling the fuel-air ratio by adjusting the air flow rate into the burner. The burner may be, for example, in a Stirling cycle engine.

Abstract: A simplified three-way piezoelectric-actuated valve is described. The valve has a valve body having an internal valve cavity, a pair of generally opposed positioning members integral to the valve body, and first, second, and common ports. At least one of the ports has a valve seat and a passageway in communication with the valve seat, the seat and the passageway being integrally formed in the valve body. A piezoelectric actuator has first and second ends. The first end is secured within the valve cavity by the positioning members and has electrical contacts for providing an electric potential to control the position of the second end. The second end is capable of flexing between a first operating position in which the first port is closed and the second port is open, and a second operating position in which the first port is open and the second port is closed.

Abstract: A simplified two-way piezoelectric-actuated valve is described. The valve has a valve body having an internal valve cavity, a pair of generally opposed positioning members integral to the valve body, and first and second ports. At least one of the ports has a valve seat and a passageway in communication with the valve seat, the seat and the passageway being integrally formed in the valve body. A piezoelectric actuator has first and second ends. The first end is secured within the valve cavity by the positioning members and has electrical contacts for providing an electric potential to control the position of the second end. The second end is capable of flexing between a closed position with respect to the valve seat and an open position with respect to the valve seat. A three-way version of the valve is also described, as is a method of manufacturing such valves.