US Patent 10036477 Variable orifice rotary valves for controlling gas flow

Gas flow control valves comprising a valve housing including a cylindrical interior passage, and a housing opening extending from the interior passage through the housing. The gas flow control valve further comprises a cylindrical rotary valve element including a sidewall, and a rotary valve element opening extending through the sidewall. The valve element is rotatably received within the interior passage of the valve housing, such that the housing opening may be selectively aligned with the rotary valve element opening, and an area of overlap of the housing opening and the valve element opening may be varied by rotating the valve element within the interior passage of the valve housing.