Patent ID: 7284542

Claim:
A gas metering device comprising: (a) a pressure chamber, (b) a discharge passage, fluidically connecting said pressure chamber to a discharge space, outside said pressure chamber, (c) a gas inlet, having one end fluidically connected to said pressure chamber and a second end, fluidically connected to a source of gas at a pressure substantially higher than the pressure in said discharge space, (d) a tapered toroidal metering valve, controlling the flow of the gas through said discharge passage, said tapered toroidal metering valve being shaped as a segment of a torus of predetermined arc length, and said segment of a torus having a first and a second end face, situated at said predetermined arc length apart, and said first end face having an area distinguishably larger than the area of said second end face, (e) actuator means, for moving the metering valve in a circular motion about the torus axis.