Patent ID: 8517107

Claim:
A variable flow resistance device defining at least one flow path, the flow path comprising: an inlet and at least a first outlet; a plurality of adjacent, fluidly inter-connected vortex chambers, the plurality of vortex chambers including a first vortex chamber and a last vortex chamber, wherein an inter-vortex opening is formed between each two adjacent vortex chambers, wherein each inter-vortex opening is positioned to direct fluid in opposite, tangential paths out of the upstream vortex chamber and into the downstream vortex chamber, whereby fluid in a clockwise vortex will tend to exit through the inter-vortex opening in a first direction and fluid in a counterclockwise vortex will tend to exit through the inter-vortex opening in a second, opposite direction, so that fluid exiting a vortex chamber from a clockwise vortex will tend to form a counterclockwise vortex in the adjacent vortex chamber and so that fluid exiting from a counterclockwise vortex will tend to form a clockwise vortex in the adjacent vortex chamber; wherein the first vortex chamber has at least a first inlet opening fluidly connected to the inlet of the flow path; a switch for changing the direction of the vortex flow in the first vortex chamber; and wherein each of the vortex chambers has an axial vortex outlet that is fluidly connected to the flow path outlet whereby the interval between the rise and decay of the vortex in the last vortex chamber is prolonged.