Feedback air-fuel control system for Stirling engines
AssigneeGas Research Institute
InventorRussell Monahan
Life of this patent
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Abstract
A control system for Stirling engines includes a feedback control from a sensor for detecting oxygen levels in the exhaust from the combustion system of the Stirling engine. The sensor generates a feedback signal which is converted for inputting into a microprocessor control system. The input signal is compared with a reference signal to readjust the air-fuel mixture set by control apparatus responsive to at least one engine operating condition such as working fluid temperature. The microprocessor control system generates control signals for both an electronic pressure regulator and a combustion blower so that both as pressure and air flow are adjusted according to engine operating requirements. Either a universal or a lean exhaust gas oxygen sensor is preferably employed in the feedback control.
Claims15
In combination with a Stirling engine having an air-fuel ratio control and an exhaust gas emission outlet, the improvement comprising:
- an oxygen sensor in communication with said exhaust gas emission outlet for generating an output signal representative of the oxygen content in said outlet;
- a sensor signal conditioning unit for adapting said output signal to a conditioned input signal for a microprocessor;
- and
- a microprocessor controlled pilot for adjusting said air-fuel control in response to said control input signal.
A method for maintaining a Stirling engine working fluid at a substantially constant temperature comprising:
- controlling the combustion energy output by controlling the air-fuel ratio supplied to the combustion system of the Stirling engine including controlling the air flow from a combustion compressor and controlling the pressure of fuel from a natural gas supply;
- sensing the oxygen level of the combustion exhaust gases and generating a control input signal;
- and
- adjusting at least one of said input air flow and gas supply pressure in response to said control input signal.
A control system for a Stirling cycle engine supplied by a source of natural gas fuel, comprising:
- microprocessor control means for generating control signals responsive to sensor inputs;
- a first engine condition sensor for detecting heat exchange temperature and generating a first response signal;
- a compressor electrically coupled for receiving a first control signal from said microprocessor control means in response to said first response signal and for discharging controlled amounts of air into the combustion chamber;
- a second engine condition sensor for detecting constituent gas levels in the combustion chamber exhaust and generating a representative response signal;
- and
- a fuel regulator electrically coupled for receiving a second control signal from said microprocessor control means in response to said representative response signal and for adjusting fuel pressure from the source to the combustion chamber.
Dependencies are inferred from the claim text.