| 摘要 |
<p>Louvre has blades which are made of extruded plastic. They have a thickened root with a hole through it into which the hinge pins fit. The main part of the blade projects from the root in a shallow curve bowed outwards. This ensures that in the closed position there is only line contact between successive blades. The blades are held on short nylon pins which fit in to the holes in the roots. The other end of each pin fits into a recess in the side of the frame which is reinforced at this point. The blade shape, mounting arrangement and material all reduce noise caused by chatter of the blades when the fan runs at slow speed.</p> |
