| 摘要 |
<p>A powered door operator 10 for use with an up-and-over door 13 installed in a garage doorway 11, comprises a reversible electric motor 14 projecting a drive shaft 17, a carrier plate 15 supporting the motor 14 from structure 16 of the garage 12, a toothed driving pulley wheel 18 mounted on the drive shaft for rotation therewith, and an idler pulley wheel 19 rotatably on a fixed bracket 21. A toothed drive belt 22 extends around the toothed wheels 18, 19 so as to form a closed loop. A link bracket 23 is attached to the back of the door 13 and secures the belt 22. The belt 22 is tensioned by jockey pulleys, 25, 26, which permit extension of the closed loop formed by the belt on initial opening of the door. In a modification (Figure 4), only part of the belt 22 is toothed and plate (15) is sprung mounted to permit extension of the closed loop. In Figs 5-8 (not shown) an arrangement having a carriage driven along a gear rack is described. <IMAGE></p> |
