| 摘要 |
C:/N r/DCC/MAG40793 25_LDOC-13M1/2012 - 13 A retractable fan blade for a combined ceiling fan and light fitting, the fitting including blade support means which in use is rotated about a fan rotation axis, the blade 5 support including means for mounting a plurality of retractable fan blades for pivoting about respective fan pivot axes between retracted and extended positions, and wherein: (i) the fan blade has a root end, tip, a leading edge and a trailing edge, the leading edge and trailing edge being concave and convex respectively when viewed in plan and, in cross-section through the blade in its retracted position at radial planes which 10 include the fan rotation axis, the cross-sectional shape of the blade is defined by upper and lower edges which include convex and concave portions respectively; (ii) the vertical height of the trailing edge above the blade support means when in its retracted position varies by less than 20% along the length of the blade; and (iii) the vertical height of the leading edge above the blade support means when 15 in its retracted position generally increases towards the tip of the blade, and the ratio of the heights of the trailing edge to the leading edge is less than about 0.7 at or near the tip of the blade. |
