| 摘要 |
The invention relates to a valve for a ventilation installation. The valve (1) encloses both a first circular pipe (5) which is provided with a first duct (50), the flowthrough area size of which is variable in order to be able to control the airflow through the valve, and also a second circular pipe (7) which is provided with a second duct (64) which is coaxial with the first pipe and the flowthrough area size of which is also variable or permanently constant or can be adjusted to a desired value and kept constant while the flowthrough area size of the first duct is throttled controllably or widened. A sleeve (15) made of flexible material is provided coaxially in the first pipe in order to bring about said control of the flowthrough area size of the first duct, there being provided both means (51, 53, 54, 60, 61, 62, 18) for turning the ends in relation to one another about the common central axis (30) of the pipes and of the sleeve, and also means (21, 26) for keeping constant the diameter of the ends of the sleeve, when the latter contracts inwardly to the centre from the maximum extended position on turning or widens from the contracted state on turning in the opposite direction. <IMAGE> |
