Self adjusting oxygen enrichment system

Claim 1

In a vehicle for operating over a range of altitudes including a maximum altitude, an improved breathing apparatus comprising: a source of pressurized air on said vehicle; enriching means for receiving said pressurized air and increasing its oxygen concentration to a preselected percentage at a generally fixed mass flow rate sufficient for breathing at said maximum altitude; breathing means for receiving air from said enrichment means for use at a demand mass flow rate which varies with changes in altitude of said vehicle; and supply means for providing additional air to said breathing means at reduced altitudes less than said maximum altitude to the extent said demand mass flow rate exceeds said fixed mass flow rate and with a reduced oxygen concentration sufficient for breathing at said reduced altitude.

Claim 17

A method of supplying air, with an oxygen level sufficient to prevent hypoxia and at mass flow rates sufficient to satisfy breathing demand in a vehicle which operates over a range of altitudes up to a maximum altitude with a corresponding range of atmospheric pressures down to a minimum pressure, to breathing air supply apparatus with a substantially constant volume demand for breathing air, said method comprising the steps of: supplying pressurized air from a source on said vehicle to an enrichment system; enriching the oxygen content of said pressurized air to a level sufficient to prevent hypoxia at said maximum altitude and minimum pressure; supplying said enriched air to said breathing apparatus at a rate sufficient to satisfy breathing demand at said minimum pressure; and adding pressurized air to said breathing apparatus as required to satisfy said fixed volume breathing demand while maintaining the oxygen content at a level sufficient to prevent hypoxia when combined with said enriched air at reduced altitudes and atmospheric pressures greater than said minimum pressure.

Claim 18

A method of supplying air, with an oxygen level sufficient to prevent hypoxia and at mass flow rates sufficient to satisfy breathing demand in a vehicle which operates over a range of altitudes up to a maximum altitude with a corresponding range of atmospheric pressures down to a minimum pressure, to breathing air supply apparatus with a substantially constant volume demand for breathing air, said method comprising the steps of: supplying pressurized air from a source on said vehicle to an enrichment system; enriching the oxygen content of said pressurized air to a level sufficient to prevent hypoxia at said maximum altitude and minimum pressure; supplying said enriched air to said breathing apparatus at a rate sufficient to satisfy breathing demand at said minimum pressure; and adding pressurized air to said breathing apparatus as required to satisfy said fixed volume breathing demand while maintaining the oxygen content at a level sufficient to prevent hypoxia when combined with said enriched air at reduced altitudes and atmospheric pressures greater than said minimum pressure.