| 摘要 |
The present invention relates to a flow rate control element for ducts, said control element operating based on the iris-diaphragm principle and including an annular housing comprised of a base part (3) with a cover part (4) made to fit thereon, and said housing having therein adapted essentially curved leaves (7), which are pivotally connected at their one ends to said housing, and further including a control ring having radial slots made thereto in which slots the other ends of the leaves are adapted to move, whereby said leaves are made steplessly rotatable between their closed and open positions by turning the control ring. The invention is implemented by forming for each leaf (7) to be installed in one part of the housing, advantageously the base part (3), a nonpenetrating indent or outdent, respectively, whereby to that side of the leaf to be installed facing said indented or outdented side is formed an essentially complementarily shaped outdent or indent, whereby the pivotal cooperation of the outdent/indent pair permits unobstructed rotation of the leaf (7) about its pivot point. |
