Importance

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Abstract

Apparatus for generating oxygen enriched air from a flow of ram air supplied to a hydraulically driven air compressor 10 by way of an inlet 11. After pressure intensification the air is delivered to a gas concentrator unit 50 (shown in FIG. 2) through a supply line 90. Molecular sieve beds provided by the concentrator unit 50 are cycled through charge/adsorption and purge/desorbtion phases by pilot valves 65, 66, 67 operated by cams 30, 31, 32 respectively, mounted for rotation on a shaft 33 driven by the compressor through a reduction gear box 35. A flueric partial pressure sensor 80 senses the partial pressure of oxygen in the oxygen-enriched air delivered from the concentrator unit and, by way of low pressure transducers 81, 82, signals a flow control valve 86 to control flow of hydraulic fluid to an inlet 19 of the compressor 10. Variation of the hydraulic flow to the compressor causes corresponding increase of decrease in the rotational speed of the shaft 33 and cams 30, 31, 32 so as to control cycling of the molecular sieve beds to vary the oxygen concentration in the delivered oxygen-enriched air to maintain the partial pressure of oxygen substantially constant irrespective of changes in aircraft altitude. The apparatus dispenses with a requirement for engine compressor stage bleed air as supply air for the concentrator unit and has minimal requirement for use of electrical systems.

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First Claim