| 摘要 |
A fluid flow control device ( 26, 28 ) comprising a guide member ( 30 ) to guide a fluid passing through a duct ( 22, 24, 76 ), the guide member ( 30 ) being movable between first and second positions; and an urging arrangement ( 32 ) capable of providing an urging force (F 1 ) to urge the guide member ( 30 ) towards the first position, characterised in that the urging arrangement ( 32 ) is a resilient torsion bar that is formed so as to allow the guide member ( 30 ) to be moved towards the second position by a pressure force (F 2 ) exceeding and opposite to the urging force (F 1 ), the pressure force (F 2 ) being provided by a pressure difference across the guide member ( 30 ).
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