| 摘要 |
PURPOSE:To reduce the leakage at the time of fully closed condition by con necting the first damper plate to the driving shaft provided in a short pipe, and turnably fitting one end of the second damper plate inside the short pipe, and connecting the idle end thereof to the driving shaft. CONSTITUTION:The first damper plate 5 is turnably fitted on the inside of a casing back plate 1. On the discharge port a ductlike short pipe 2 is connected, end one end of the second damper plate 12 is turnably fitted on the inside of the short pipe 2, and the idle end thereof is supported by a driving shaft 11 in the short pipe 2. Thus, the air leakage at the time of fully closed condition can be significantly reduced as compared with the conventional device.
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