Thermodynamic reciprocating machine with controlled fuel/air supply

Claim 1

In a thermodynamic engine including a burner for combustion of fuel and air, with a fuel inlet fed by a fuel duct, an air inlet fed by an air duct, a flow valve in each of said ducts, a heater heated by the burner, a temperature sensing element indicating heater temperature, a device for supplying air to said air duct, drive means from said engine to said device, the improvement in combination therewith of control apparatus responsive to at least one parameter of the engine for controlling said fuel flow and for controlling said air flow to be proportionate to said fuel flow, comprising, an air flow restricting element in the air duct intermediate said air supply device and the air flow valve responsive to air flow therethrough and providing a corresponding 1st signal, a source of constant pressure fluid medium, an outlet duct for said medium flow, a main valve controlling flow through said outlet duct, a second flow restricting element in said outlet duct downstream of said main valve for providiNg a second flow signal, a fixed restriction in said outlet duct downstream of said second flowrestricting element, a control apparatus responsive to signals from said temperature sensing element for opening wider said fuel duct valve and said main valve in said medium outlet duct when temperature is low, and vice versus, a control member receiving said first and second flow signals respectively from said flow restricting elements in said air flow and fluid medium flow ducts, for determining the difference between said signals, and producing a resulting control signal to said air flow valve.