Patent ID: 8381817

Claim:
A variable flow resistance device comprising: a plurality of flow paths, each such flow path comprising: an inlet; an outlet; a vortex chamber having an axial outlet continuous with the outlet of the flow path; a Y-shaped bi-stable fluidic switch that receives fluid from the inlet and outputs fluid to the vortex chamber alternately along two diverging paths, both of which are tangential to the vortex chamber to produce alternately clockwise and counterclockwise vortices, the switch having first and second control ports; and a feedback control circuit that transmits fluid alternately from clockwise and counterclockwise vortices in the vortex chamber to the control ports of the fluidic switch to alternate flow, the feedback control circuit comprising a common section between the first and second control ports through which fluid flows alternately in opposite directions to direct fluid from the vortex chamber alternately to the first and second control ports; wherein the inlets of the flow paths in the plurality of flow paths are fluidly interconnected and the outlets of the flow paths in the plurality of flow paths are fluidly interconnected to provide parallel flow through the flow paths.