US Patent 7520298 Rotary fluid flow valve

A rotary valve having inner and outer sleeves includes multiple ports configured to provide pressure and vacuum pulses when the sleeves are rotated with respect to each other. A source of pressure and vacuum is connected to the rotary valve, and the inner sleeve is rotated to generate pressure and vacuum pulses. The alternating pressure and vacuum pulses may be used to remove obstructions in conduits such as piping systems. The rotary valve may also provide static positions where no vacuum or pressure is available. The valve may be motor driven and the pressure/vacuum pulse frequency may be controlled based upon the relative speed of rotation of the sleeves.