Aircraft aircrew life support systems

• US 5,314,402 A
• Filed: 06/11/1991
• Issued: 05/24/1994
• Est. Priority Date: 06/19/1990
• Status: Expired due to Term

• Current Assignee: Normalair Garrett Holdings Ltd. (Honeywell International Inc.)
• Original Assignee: Normalair Garrett Holdings Ltd. (Honeywell International Inc.)
• Inventors: Rowland, Peter J., Harral, Michael W., Foote, James C.
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): Jastrzab, Jeffrey R.
• Application Number:
  US07/713,103
• Time in Patent Office: 1,078 Days
• Field of Search: 600/19, 600/20, 128/202.11
• US Class Current: 600/20
• CPC Class Codes: A62B 17/008 High-altitude pressure suits
• CPC Class Codes: B64D 10/00 Flight suits helmets in general A42B3/00; breathing helmets A62B18/00

Abstract

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_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_Z and cabin ambient pressure signals P_AMB input to the computer by sensors 121 and 122, respectively. The ECU compares an existing G-suit inflation pressure P_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.

Claims

1. A method of controlling inflation pressure of an aircrew G-suit in protecting an aircrew member against G-load and against exposure to altitude above a predetermined level, comprising the steps of:

storing in an aircraft on-board systems computer a schedule of G-suit inflation pressure against increasing acceleration along a vertical axis of the aircraft and a schedule of G-suit inflation pressure against decreasing cabin ambient pressure;

inputting to the computer signals representative of acceleration sensed along the vertical axis of the aircraft and signals representative of cabin ambient pressure;

looking up in the schedules and presenting requirements for G-suit inflation pressure;

determining by control logic programmed in the computer a higher one of values for G-suit inflation pressure in the vent of simultaneous acceleration and cabin ambient pressure signal inputs requiring inflation of the G-suit;

generating in the computer a G-suit inflation pressure demand signal;

transmitting the G-suit inflation pressure demand signal to an electronic control unit dedicated to control of G-suit inflation pressure;

sensing pressure existing in the G-suit or a pressure substantially corresponding thereto;

feeding back to the electronic control unit a signal representative of existing G-suit pressure;

comparing the existing G-suit pressure signal with the G-suit inflation pressure demand signal;

generating a compensated error signal;

combining the compensated error signal with the G-suit inflation pressure demand signal to provide a servo-demand signal;

transmitting the servo-demand signal to servo-control valve means for regulation of a servo-pressure which acts to close G-suit vent valve means adapted when open for communicating the interior of the G-suit with ambient and to open G-suit inflation gas supply valve means adapted for controlling delivery of inflation gas to the interior of the G-suit whereby the G-suit is inflated to a required pressure.

2. A method as claimed in claim 1, further comprising the step of generating negative value pressure demand signals in the computer at low levels of acceleration and transmitting the negative value pressure demand signals to the electronic control unit whereby the G-suit is not inflated until a predetermined G-level is exceeded.

3. An aircraft aircrew life support G-suit system comprising a breathing demand regulator means adapted to be connected with a breathing gas source for regulating supply of breathing gas to a breathing mask in response to breathing demands of an aircrew member, G-suit inflation control means comprising servo-control valve means for regulating a servo-pressure for control of a G-suit inflation gas supply valve means controlling flow of high pressure gas from high pressure gas inlet means for connecting said gas supply valve means with a source of said gas to high pressure gas outlet means for connecting said gas supply valve means with said G-suit and for control of a G-suit inflation gas vent valve means for venting high pressure gas from the G-suit to ambient;

means for sensing acceleration along a vertical axis of said aircraft and for outputting signals representative thereof;

means for sensing pressure internal of an aircraft cabin and for outputting signals representative thereof;

an aircraft on-board systems computer means having a memory means storing schedules of G-suit inflation pressure against increasing acceleration along the aircraft vertical axis and against decreasing aircraft cabin pressure and connected for receiving signals from said acceleration sensing means and from said cabin pressure sensing means, said computer means being programmed to look-up in said schedules and present values of G-suit inflation pressure appropriate to sensed acceleration and cabin pressure and being further programmed with logic for determining a higher one of values for inflation pressure in the event of simultaneous acceleration and cabin pressure inputs requiring inflation of the G-suit, said computer means being adapted for generating a G-suit inflation pressure demand signal;

an electronic control unit means connected for receiving said G-suit inflation pressure demand signal from said computer means;

means for sensing pressure existing in said G-suit and connected for transmitting a feedback signal representative of existing G-suit pressure to said electronic control unit means;

said electronic control unit means further including means for comparing said existing G-suit pressure signal with said demand signal, means for generating a compensated error signal, and means for combining said compensated error signal with said demand signal to provide a servo-demand signal;

said electronic control unit means being connected for transmitting said servo-demand signal to said servo-control valve means for regulation of the servo-pressure whereby the G-suit inflation pressure is adjusted towards the required value.

4. A system as claimed in claim 3, wherein the system'"'"'s computer means is programmed to output negative value demand signals at low levels of acceleration and the electronic control unit includes means for rejecting such signals so that the G-suit is not inflated until a predetermined G-level is exceeded.

5. A system as claimed in claim 4, wherein the electronic control unit comprises a negative value rejection circuit, a first summing circuit, a compensation circuit, a second summing circuit, a pulse width modulation circuit and a torque motor drive circuit.

6. A system as claimed in claim 5, wherein the negative value rejection circuit comprises negative value demand signal rejection means and positive value demand signal pass means the first summing circuit being connected for receiving positive value demand signals for summing with G-suit inflation pressure feedback signals in provision of an error signal.

7. A system as claimed in claim 6, wherein the electronic control unit further comprises means for allowing negative value demand signals to pass to the second summing circuit for summing with an offset signal in obtainment of a servo-demand signal that sets a servo-pressure of value marginally below that required for commencement of control of the G-suit inflation gas supply valve means and the G-suit inflation gas vent valve means.

8. A system as claimed in claim 3, wherein the breathing demand regulator means includes a breathing pressure control chamber for developing a control pressure therein which determines the breathing gas pressure delivered by the regulator means, the servo-control valve means comprises a torque motor-controlled valve means for regulating a servo-flow to provide servo-pressure which acts to move the G-suit vent valve means towards a closed position and the inflation gas supply valve means towards an open position whereby inflation gas flows from the high pressure gas inlet means to the high pressure gas outlet means, the torque motor-controlled valve means being biased in absence of electrical power to close a vent means communicating servo-flow with ambient, and a solenoid-operated valve means biased in absence of electrical power to a position communicating servo-flow with one side of a valve means adapted for sensing on its opposite side pressure in the breathing pressure control chamber whereby servo-pressure is regulated to set a G-suit inflation pressure that is a predetermined multiple of breathing gas delivery pressure.