Control of gaseous medium flow through pipe - uses flap bent near supporting shaft and acting against spring bias but never completely closing pipe cross=section

摘要

The pipe clear cross-section can be varied by a flap rotatable about a diametral shaft by the flow pressure against the pressure of a spring. The flap is bent near its axis of rotation. One of its sides is in the open position parallel to the pipe axis, and in its closed position oblique to the axis and pointing backward. The other side is in its open position oblique and pointing forward, and in the closed position perpendicular to the pipe axis. The flap (4) covers only part of the whole surface which would in the closed position completely close the pipe clear cross-section.