Normalair-garrett (holdings) Limited

Michael W Harral

James C Foote

Peter J Rowland

Humphrey A Hamlin

Robin H Searle

Eric L Rendell

Inflation pressure of an aircrew G-suit is set by a servo-pressure which controls movement of inflation gas supply and vent valves 126 and 127, respectively. Servo-pressure is regulated by a torque motor controlled valve 124, 125 which receives a servo-demand signal from an electronic control unit (ECU) 123. The ECU receives an inflation pressure demand signal P.sub.DEM from an aircraft systems computer 120 which stores schedules of G-suit inflation pressure against increasing acceleration and decreasing cabin ambient pressure. The computer is programmed to look-up and output the higher one of values for inflation pressure dependent upon values of acceleration signals G.sub.Z and cabin ambient pressure signals P.sub.AMB input to the computer by sensors 121 and 122, respectively. The ECU compares an existing G-suit inflation pressure P.sub.O signal with the inflation pressure demand signal and generates a compensated error signal which is combined with the inflation pressure demand signal to provide the servo-demand signal. The use of the ECU for the computationally intensive control task optimizes the use of the aircraft system computer. A combined breathing demand regulator and G-suit inflation pressure control valve which continues to function in the absence of electrical power after bail-out from an aircraft is also disclosed.

Aircraft aircrew life support systems

A breathing demand regulator for use in aircrew life support apparatus has an aneroid capsule 56 coacting with a valve head 50 to restrict outflow from a breathing pressure control chamber 32. The aneroid capsule expands to move the valve head in the event of aircraft cabin altitude rising above a predetermined level due to loss of cabin pressure. An end face 53 of a valve stem 51 supporting the valve head senses inflation pressure of an aircrew G-suit by way of a passageway 59 for movement of the valve head in the presence of G-load. This arrangement provides for increased control pressure and, hence, increased breathing gas pressure in a regulator outlet 13, in meeting the higher of requirements for positive pressure breathing to protect an aircrew member exposed to both G-load and high aircraft ambient altitude (say above 12000 meters). The regulator is disclosed in combination with an anti-G valve arrangement 90, 100 and a G-suit inflation control valve arrangement 60, 61 and 120, 121 that provides the higher of G-suit inflation pressure requirement for protecting the aircrew member when exposed to high aircraft ambient altitude in the presence of G-load.

Aircraft aircrew life support apparatus

A breathing gas regulator for regulating delivery of breathing gas to an aircrew member wearing a liquid filled G-suit includes a relay valve having a diaphragm mounted valve plate for sensing G-suit hydrostatic pressure. A bleed of breathing gas is supplied to the relay valve by way of a pneumatic link and is vented to ambient through a vent outlet. As G-suit hydrostatic pressure rises due to increasing G-load the valve plate moves towards closing the vent outlet. Above a predetermined G-load, with the vent outlet closed, a pneumatic signal is generated in the pneumatic link and is applied to an end face of a valve controlling outflow from a breathing-pressure control chamber so that pressure in the control chamber increases to set a breathing gas pressure at the regulator outlet appropriate to positive pressure breathing. The regulator provides a low risk solution to interface with a liquid filled G-suit because in the event of leakage of liquid into the relay valve the liquid is able to bleed to ambient through the vent outlet.

Aircrew breathing gas regulators

A system and apparatus are disclosed for providing oxygen-rich gas for breathing by aircrew and passengers of commercial passenger aircraft. Oxygen-rich gas output by molecular sieve concentrator apparatus 11 is delivered by way of a compressor 17 and a priority valve 24 to a flight crew gas storage cylinder 22 and passenger gas storage cylinders 23. An electronic control unit (ECU) 38 controls cycling of the concentrator apparatus 11 in obtainment of gas enriched with oxygen to at least 90%. The ECU is connected for receiving signals from a monitor 35 which senses the content of oxygen in gas delivered by the concentrator apparatus. The ECU receives signals from pressure sensors 42 and 43 in the cylinders 22 and 23 to initiate start up of the system when the content of these cylinders is sensed to have fallen below a predetermined value. The ECU is connected to switch the priority valve for preferential charging of the crew cylinder when both sets of cylinders require charging. The ECU is further connected for opening a vent valve 46 whereby on start-up of the system, gas delivered by the concentrator apparatus is vented to ambient until the oxygen concentration is sensed to be 90% or more. The system reduces the requirement for ground servicing and weight of oxygen gas storage cylinders carried by present day passenger carrying aircraft. Also, it enables the number of cylinders to be kept at a minimum in meeting the requirements for emergency oxygen on new air routes which are now being developed.

Oxygen-rich gas breathing systems for passenger carrying aircraft

The oxygen content of oxygen-enriched air is monitored by a solid electrolyte amperometric sensor which does not require a reference gas for comparison with the oxygen-enriched air. When oxygen-enriched air is supplied to the sensor a current signal is output by the sensor. The current signal is converted to a voltage signal which is processed by a signal processor storing an oxygen diffusion equation in the form of a look-up table to obtain an oxygen percentage concentration signal. An oxygen partial pressure signal may be obtained by supplying ambient pressure signals from an ambient pressure sensor to the signal processor for multiplication with the oxygen concentration signal.

Oxygen monitoring method and apparatus

An aircraft on-board oxygen generation system having a controller 14 for cycling sieve beds of amolecular sieve-type gas separation system 10, provides product gas having a partial pressure of oxygen that more closely approaches the ideal value at any cabin altitude within the operating range of the aircraft. The controller stores a look-up table of desired product gas oxygen content at various altitude levels within the operating range and displays desired product gas oxygen content at altitudes sensed by an altitude sensor 17 for comparison with delivered product gas oxygen content sensed by oxygen content sensor 19. The controller provides for a range of selectable cycle time and adjusts the cycle time in the sense required to null the difference between displayed and sensed oxygen content of the product gas.

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Yeovil, United Kingdom

Michael W Harral