Patent ID: 8517106

Claim:
A variable flow resistance device defining at least one flow path comprising: an inlet and an outlet; a jet chamber having first and second control ports; a nozzle to direct fluid from the inlet into the jet chamber; first and second input channels diverging from the jet chamber; a vortex chamber continuous with the outlet and having first and second inlet openings and first and second feedback outlets, wherein the first and second inlet openings of the vortex chamber are positioned to direct fluid in opposite, tangential paths into the vortex chamber so that fluid entering the first input inlet opening produces a clockwise vortex and fluid entering the second inlet opening produces a counterclockwise vortex, and wherein the first and second feedback outlets of the vortex chamber are positioned to direct fluid in opposite, tangential paths out of the vortex chamber, whereby fluid in a clockwise vortex will tend to exit through the second feedback outlet and fluid in a counterclockwise vortex will tend to exit through the first feedback outlet; wherein the first and second inlet openings of the vortex chamber are continuous with the first and second input channels and wherein each of the first and second input channels defines a straight flow path from the jet chamber to the first and second inlet openings, respectively, of the vortex chamber; a first feedback channel extending from the first feedback outlet of the vortex chamber to the first control port in the jet chamber; and a second feedback channel extending from the second feedback outlet of the vortex chamber to the second control port in the jet chamber; whereby fluid from a counter-clockwise vortex passing through the first feedback channel to the first control port will tend to switch fluid flow from the second input channel to the first input channel, and fluid from a clockwise vortex passing through the second feedback channel to the second control port will tend to switch fluid flow from the first input channel to the second input channel.