Abstract: This invention relates to a rotary valve device for controlling and distributing flow of a fluid medium directly in response to the rotary motion of a motor shaft. Fluid medium is continuously supplied to a cavitated disk through a manifold by a pump source where the cavitated disk rotates at the same rotational speed as the motor shaft. The cavitated disk has a first void region in continuous fluid communication with the pump source and alternately communicates with cylinder conduits to drive a piston. A second void region in the cavitated disk is so dimensioned and proportioned to permit fluid medium to be alternately exhausted from the cylinder and to be distributed to exhaust conduits and then to the atmosphere.

Abstract: A system including the method employed, for controlling the flow of a pressurized gas through a variable orifice flow control valve in a pressurized gas conduit system, such as a ventilator, in response to either a desired flow rate/volume input signal, a desired pressure signal or both. With respect to the flow rate input signal, the system generates a flow signal indicative of the actual flow rate of gas through the flow control valve by measuring the pressure drop across the valve and using the actual orifice area based on a control valve position signal given to the valve. This flow signal is compared to the flow rate input signal to give a correction signal which is used to form a volume flow reference signal. With respect to the desired pressure signal, a signal indicative of the effective pressure at a set location in the system is compared to the desired pressure signal and processed to give a pressure flow reference signal.