GB1493603A - Impulse generator for use with a rotating drive - Google Patents

Abstract

1493603 Cams; valves F LOCK 23 Sept 1974 [21 Sept 1973] 41359/74 Headings F2K and F2V [Also in Division H1] A generator for use with a rotating drive to provide an electric or pneumatic impulse after a number of revolutions comprises a switch unit 19 (20), at least two indexing gear-wheels or sprockets 5, 6 (7, 8) arranged coaxially and having equal crown and root diameters of the teeth circle but different numbers of teeth, wherein the gear-wheels or sprockets have mounted thereon, in an angularly adjustable manner, respective cam rings 11, 12 (13, 14) and are driven at different speeds by engaging their teeth with a common pinion or sprocket or respective pinions and sprockets on a drive shaft of the rotating drive, each cam ring having a lobe or depression such as 12a, and the arrangement being such that the switch unit is actuated when the lobes or depressions are aligned with each other and with a fixed datum. As shown in Figs. 1 and 2 the device forms a double limit switch for electric control of greenhouse windows, for example. A sealed chamber 1, through which drive shaft 3 passes, houses two switches 19, 20 mounted on a plate 16 secured to a fixed spindle 10. Spur gearing 4 meshes with two pairs of gears 5, 6 and 7, 8, loosely journalled on fixed spindle 10, and the gears of each pair have 84 and 88 teeth respectively. Annular cam rings 11, 12, 13 and 14 located on respective hubs, such as 8a, are adjustably secured by grub screws 24 such that the recesses 11a, 12a coincide to operate switch 19 when the windows are closed and recesses in cam rings 13, 14 coincide to operate switch 20 when the windows are fully open. One of the cam rings may have more than one recess, for example, four (as in Fig. 6, not shown) and thus produce impulses after 6, 15, 26 and 44 rotations of drive shaft 3. A very compact arrangement using coincidence of three cam-gears (46, 47, 48, Fig. 7, not shown) has hollow hubs one within another and the addition of another set of cam-gears in mirror image fashion (50) may provide double limit switching with extensive movement range. The embodiment of Figs. 8 and 9 uses a microswitch 59 with an actuating lever having a laterally flexible portion 60 and a rod portion 62 which follows a groove formed by conical surfaces 55, 56 of two gears 53, 54, each having a respective lobe or wing such as 58. Passage of one lobe merely deflects lever end 60 laterally to left (Fig. 10, not shown) or right (Fig. 11, not shown) without actuating switch 59, but when the lobes coincide (Fig. 12, not shown) the arm is lifted radially and switch 59 is operated.