GB1230391A - - Google Patents

Abstract

1,230,391. Operating mechanism for shutters. H. SUZUKI. 1 May, 1968, No. 20704/68. Heading E2M. [Also in Divisions A5 and F2] An operating mechanism for manual and automatic operation of a shutter consisting of a number of slats comprises a rotary drum usually rotatably mounted on a shaft 3 for carrying the shutter, first and second springs 8 and 17 for applying torque to the drum to urge it to rotate in one sense and operating means for rapidly releasing tension in the second spring so that it can subsequently be tensioned by rotation of the drum in the opposite sense, the operating means being connected to, and actuated by fusion of, a fusible linkage such that, in use, the first and second springs together counterbalance the shutter whilst the linkage is intact but, on fusion of the linkage and release of tension in the second spring, the shutter will roll down thereby tensioning the second spring so that rolling- down occurs non-acceleratively. The operating means may include a pawl lever 18 connected via a wire 22 with the fusible linkage and engageable with a ratchet wheel 14 mounted on the shaft. The spring 17, which may be a helical or volute coil spring, is disposed about the shaft 3 with one end fixed to a boss 14a on the ratchet wheel and its other end attached to a disc 7 rotatably mounted on the shaft. The spring 8 is attached at one end to an analagous disc 6 at the other end of the shaft and at its other end is fixed to the shaft. The shaft is journalled in support members 4 and 5 and an adjusting disc 9 is pinned to the shaft between support 4 and disc 6 and is provided with a number of holes through which a pin 10 may pass into a hole 4a in the support to prevent rotation of the shaft. The spring 8 urges disc 6 to rotate so as to wind up the shutter. In operation, the mechanism is assembled with wire 22 slack and pawl lever 18 disengaged from ratchet 21 with all springs untensioned and disc 9 disconnected from support 4. The shutter is rolled down in guide rails 2 to its normal open (retracted) position and the disc 9 rotated until spring 8 is sufficiently tensioned to balance the moment of the shutter. The disc 9 is fixed to the support by means of pin 10 and the shutter rolled down to its fully extended position. The spring 17 is then tensioned by rotation of ratchet wheel 14 until the shutter returns to its normal open position. The pawl 20 is engaged in a ratchet 21 and wire 22 connected to the fusible linkage and made taut. A set lever 26 is rotated clockwise about a pivot 27 until a spring 29 urges lever 26 against step pin 31 (to give the position shown in Fig 3). When the linkage is fused, the wire 22 is untensed allowing lever 18 to move anti-clockwise about pivot 19 in response to spring 29 and thus releases the ratchet wheel which rotates rapidly due to the tension in spring 17. However, the movement of lever 18 causes lever 25 to move anti-clockwise until a kick-plate 24 strikes a pin 12 protruding from the disc 7 (the position indicated in phantom in Fig. 4). On striking pin 12, lever 25 is moved clockwise pulling lever 26 overcentre in an anti-clockwise direction. This untenses spring 29 and imparts a compressive force via that spring urging lever 18 clockwise until pawl 20 again engages the ratchet wheel 14 to prevent further rotation thereof (solid lines in Fig. 4). The balance between springs 8 and 17 and the moment of the shutter is now lost and the shutter starts to unroll, its tendency to accelerate being checked because spring 17 absorbs proportionally the increased force generated on unrolling. In a modification (Figs. 5-7 not shown), the operating mechanism (51) comprises a disc rotatably mounted on a pipe (54) with a coil spring extending about the pipe and attached thereto at one end and to the disc at its other end. A belt (67) extends from the set lever (64) to a fixing seat (69) attached to ratchet wheel (53). A second stop pin (75) is also provided and protrudes from the set lever. Operation is as described above for the first embodiment. In a further modification (Fig. 8 not shown), the disc 7 differs from that of Figs. 1-4 in that it has no striking pin 12 and has at its inner end a boss (76). Also, brackets 36 are replaced by brackets 77 spaced at the circumference of disc 7 and supporting a drum 78 about which the shutter can be wound.