Abstract: A control system for moving a piston in a reciprocating piston respirator which utilizes predictive servo control techniques. Present invention uses nonlinear time domain analysis rather than linear frequency domain analysis to produce a predictive servo control system for precisely controlling the movement of a piston in a reciprocating piston respirator. A plurality of flow profiles can be produced using stored factor tables. Current pressure and position information are used in the predictive servo control system.

Abstract: A variable flow reciprocating piston respirator system which is capable of providing a substantially constant oxygen enrichment over an entire inspiration stroke of a variable flow respirator output. A proportional control valve is used to deliver oxygen from an oxygen supply tank to the output of a reciprocation piston pump. A microprocessor controls the magnitude of opening of the proportional valve to insure that a proper overall volume of the output is produced with the proper percentage of enrichment of oxygen.

Abstract: A pump primarily intended for use in a portable ventilator. The pump includes a piston-cylinder arrangement in which the piston is reciprocally moved within the cylinder by rotating a shaft. The shaft is threaded and mounted for rotation within the cylinder at a fixed location along the axis of the cylinder. The piston has an aperture through its center and the shaft extends substantially between the end walls of the cylinder and through the center of the piston. The piston is held against rotation relative to the shaft and cylinder by a collapsible hinge and is attached to the shaft by an arrangement including a ball nut and sealing nut. The piston forms a variable volume, working chamber with one end of the cylinder and in operation, the shaft is selectively rotated to move the piston toward and away from the end wall. This positioning of the shaft within the cylinder reduces the overall size of the pump and specifically adapts it for use in a portable ventilator in which size limitations are critical.