Automatic fluid supply control apparatus

Claim 1

OXYGEN BREATHING APPARATUS FOR SUPPLYING OXYGEN TO A PERSON BREATHING, COMPRISING A FACE MASK HAVING THE GAS INLET; MEANS FOR CONNECTING THE MASK WITH THE FACE OF THE PERSON, SO THAT THE MASK AND THE FACE WILL CO-OPERATE TO FORM A MASK CAVITY WITH WHICH THE NOSE AND MOUTH OF THE PERSON COMMUNICATE; A CAPACITANCE DIFFERENTIAL GASPRESSURE TRANSDUCER HAVING FIRST AND SECOND CHAMBERS AND A DIAPHRAGM PROVIDING A CAPACITOR DIELECTRIC THAT SEPARATES THE CHAMBERS; THE WALL OF THE SECOND CHAMBER PROVIDING ONE ELECTRODE AND THE FACE OF THE DIAPHRAGM EXPOSED WITHIN THE FIRST CHAMBER PROVIDING THE OTHER ELECTRODE, WHEREBY RELATIVE MOVEMENT OF THE ELECTRODES VARIES THER CAPACITANCE GENERATING A VARIABLE ELECTRIC OUTPUT SIGNAL; A PRESSURE DATUM CHAMBER FOR PROVIDING GAS AT AN ADJUSTABLE PREDETERMINED PRESSURE; MEANS FOR MOUNTING THE TRANSDUCER IN THE MASK AND FOR PERMITTING GAS IN THE MASK CAVITY TO COMMUNICATE WITH THE FIRST CHAMBER OF THE TRANSDUCER, AND MEANS FOR CONVEYING GAS BETWEEN THE PRESSURE DATUM CHAMBER AND THE SECOND CHAMBER OF THE TRANSDUCER, SO THAT THE CAPACITANCE OF THE TRANSDUCER WILL BE RELATED TO A DIFFERENCE BETWEEN THE PRESSURES IN THE MASK CAVITY AND IN THE DATUM CHAMBER, SO LONG AS THE PRESSURE IN THE DATUM CHAMBER IS AT LEAST AS GREAT AS THE PRESSURE IN THE MASK CAVITY; AN ELECTRICALLY ACTUABLE OXYGEN FLOW CONTROL VALVE HAVING AN OXYGEN INLET, AN OXYGEN OUTLET AND ELECTRONIC CONTROL DEVICE FOR SUPPLYING AN ELECTRIC CONTROL SIGNAL TO ACTUATE THE VALVE SO THAT OXYGEN MAY PASS FROM THE INLET TO THE OUTLET, ACCORDING TO THE MAGNITUDE OF THE CONTROL SIGNAL; MEANS FOR CONNECTING THE CONTROL VALVE OUTLET TO THE GAS INLET OF THE FACE MASK; MEANS FOR CONNECTING THE CONTROL VALVE INLET TO A SOURCE OF OXYGEN AT A PRESSURE GREATER THAN THE DESIRED MAXIMUM PRESSURE IN THE MASK CAVITY; THE ELECTRONIC CONTROL DEVICE HAVING INPUT AND OUTPUT CONNECTIONS AND ADAPTED TO PROVIDE AN ELECTRIC CONTROL SIGNAL ACCORDING TO THE CAPACITANCE AT THE INPUT CONNECTION; MEANS FOR ELECTRICALLY CONNECTING THE INPUT AND OUTPUT CONNECTIONS OF SAID DEVICE TO THE ELECTRODES OF THE CAPACITANCE TRANSDUCER AND TO THE OXYGEN FLOW CONTROL VALVE, RESPECTIVELY, SO THAT OXYGEN MAY BE ADMITTED TO THE MASK CAVITY ACCORDING TO THE DEMAND OF THE PERSON BREATHING AND INHALING; DAMPING MEANS ASSOCIATED WITH THE MEANS FOR CONVEYING GAS BETWEEN THE DATUM PRESSURE CHAMBER AND THE SECOND CHAMBER OF THE TRANSDUCER TO ALLOW STABLE OPERATION OF THE APPARATUS THROUGHOUT A DESIRED RANGE OF OPERATION; A BIASED RELIEF VALVE, HAVING A GAS INLET AND A GAS OUTLET, AND MEANS, CONNECTED TO THE DATUM PRESSURE CHAMBER, FOR BIASING THE VALVE TO A CLOSED POSITION; MEANS CONNECTING THE INLET AND THE OUTLET OF THE RELIEF VALVE TO THE MASK CAVITY AND SO ATMOSPHERE, RESPECTIVELY, SO THAT THE RELIEF VALVE WILL REMAIN OPEN SO LONG AS THE PRESSURE WITHIN THE MASK CAVITY EXCEEDS THAT IN THE DATUM CHAMBER, THEREBY ALLOWING GAS TO EXHAUST FROM THE MASK CAVITY TO THE AMBIENT ATMOSPHERE, WHEN THE PRESSURE IN THE DATUM PRESURE CHAMBER EXCEEDS THE AMBIENT ATMOSPHERIC PRESSURE, AND THEREBY RELEASING GAS EXHALED BY THE PERSON BREATHING.