Abstract: A control device for molecular sieve on-board oxygen generating systems measures both temperature and pressure of the inlet air of an oxygen generating system. An electronic control unit applies pressure limits to a pressure measurement signal and combines it with a temperature measurement signal to produce a composite analog signal responsive to both temperature and pressure inlet air conditions. This analog signal is linearly converted to a frequency signal, whereupon the frequency signal is divided by a constant in order to produce a drive signal for control of the absorb/vent bed cycle valves. Composition control is achieved by venting product mixture as required. Inlet air pressures down to 5 PSIG (pounds per square inch gauge) produce correct system operation, and the quantity of conditioned air required is automatically limited so that system efficiency is higher than prior art systems.

Abstract: A correction mechanism for supplying an altimeter indicator with a rotational torque to compensate for the non-linear relationship between pressure altitude and barometric pressure. The correction mechanism has a first gear for receiving an input force and a second gear connected to the first gear. The second gear is eccentrically located on a shaft which connects a third gear with the altitude indicator. Because of the eccentricity of the second gear the line of action between the second gear and the first gear causes the shaft to rotate the third gear through a varying arcuate length for each tooth engagement.