Control system and method for a pressure responsive fuel regulator

A control system for a pressure-responsive fuel flow regulator, comprising means for providing a source of driving pressure;

• a pressure ratio servo responsive to application of the driving pressure for adjusting the pressure level thereof to provide an output control pressure comprising a constant predetermined function of absolute ambient pressure;
• means for providing a source of ram air pressure;
• valve means movable between a first position for coupling the control pressure to the regulator, and a second position for coupling the ram air pressure to the regulator for controlling regulator fuel flow;
• and switch means for controllably shifting said valve means between said first and second positions.

A control system for a pressure-responsive fuel flow regulator, comprising means for providing a source of driving pressure;

• a pressure ratio servo responsive to application of the driving pressure for adjusting the pressure level thereof to provide an output control pressure comprising a constant predetermined function of absolute ambient pressure, said servo including means forming a pressure modulation chamber within said servo and having a pair of generally opposed valve seats, a pair of valve balls mechanically linked together for respectively closing said valve seats, a double-ended servo balance beam pivoted within said servo, a linkage arm connecting said valve balls to said balance beam, and means coupled to said beam and responsive to absolute ambient pressure for modulating the position of said valve balls with respect to said valve seats whereby the pressure within said servo comprises the control pressure;
• means for providing a source of ram air pressure;
• valve means movable between a first position for coupling the control pressure to the regulator, and a second position for coupling the ram air pressure to the regulator for controlling regulator fuel flow;
• and switch means for controllably shifting said valve means between said first and second positions.

A control system for a pressure-responsive fuel flow regulator, comprising means for providing a source of driving pressure;

• a pressure ratio servo responsive to application of the driving pressure for adjusting the pressure level thereof to provide an output control pressure comprising a constant predetermined function of absolute ambient pressure, said servo including means forming a pressure modulation chamber within said servo and having a pair of generally opposed valve seats, a pair of valve balls mechanically linked together for respectively closing said valve seats, a double-ended servo balance beam pivoted within said servo, movable pivot means pivotally carrying said balance beam, a linkage arm connecting said balance beam with said valve balls, a spring-biased diaphragm assembly coupled generally to one end of said beam and including means for applying ambient pressure to said diaphragm, an evacuated spring-bellows assembly coupled generally to the other end of said beam for adjusting the position of the beam in response to absolute pressure, whereby the position of said beam is adjusted for modulating the position of said valve balls so that the pressure within said servo comprises the control pressure;
• means for providing a source of ram air pressure;
• valve means movable between a first position for coupling the control pressure to the regulator, and a second position for coupling the ram air pressure to the regulator for controlling regulator fuel flow;
• and switch means for controllably shifting said valve means between said first and second positions.

A method of controlling a pressure-responsive fuel flow regulator, comprising the steps of supplying a source of driving pressure to a pressure ratio servo;

• altering the pressure level of the driving pressure within said servo to provide an output control pressure comprising a predetermined function of absolute ambient pressure;
• said altering step including supplying the driving pressure to a pressure modulation chamber within the servo having a pair of generally opposed valve ports and a pair of valve balls linked together for respectively closing the ports, connecting the valve balls to a double-ended servo balance beam pivotally carried within the servo, and connecting the beam to means responsive to absolute ambient air pressure for modulating the position of the valve balls whereby the pressure within the servo comprises the control pressure, providing a source of ram air pressure;
• coupling the control pressure and the ram air pressure to valve means;
• and controllably switching the valve means between a first position for coupling the control pressure to the regulator, and a second position for coupling the ram air pressure to the regulator for controlling regulator fuel flow.