| 摘要 |
PURPOSE:To reduce the pressure loss by mounting a blade vane 6 which generates a lift by a blast to actuate a connecting rod opening or closing a shutter, and providing a spring supporting the weights of the connecting rod and the blade vane to close the shutter. CONSTITUTION:A shutter 2 is opened in a direction of arrow 104 against a force exerted by a spring 7 by the pressure of a blast, and the blast is discharged in the direction of arrow 102. Upon this occasion, the blast passes the circumference of the blade vane 6, whereby a force (lift) in the direction of arrow 103 is produced in the blade vane 6 to push down the connecting rod 5 in the direction of arrow 105. For this reason, the shutter 2 is opened further in the direction of arrow 104. A part where the pressure loss is generated that is, the pressure loss generated for opening the shutter 2 and that due to the opening angle of the shutter 2 can be reduced to the minimum by utilizing the lift of the blade vane 6.
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