GB896896A - Improvements in actuators for elements such as valves - Google Patents

Abstract

896,896. Claw clutches; clutch control; slip couplings. JONES, TATE & CO. Ltd. Aug. 26, 1960 [Aug. 31, 1959], No. 29619/59. Class 80 (2). [Also in Group XXIX] The threaded stem 2, Fig. 1, of a valve or other apparatus, which may be driven by an electric motor 68 or a hand wheel 63, is disposed in a sleeve 3 to which is fixed a spur-wheel 15 meshing with a pinion 18 keyed to a shaft 19 that is rotated through a coupling consisting of three pawls 26 on a dished gear 24, only one pawl being shown, each pawl co-operating with a ball 27 carried by a disc 29 keyed to the shaft 19; the balls 27 are loaded by a spring 32 through a plate 31. When the gear 24 is driven the downward movement of the plate 31 resulting from coaction of the pawls and balls is a measure of the torque transmitted and such movement may be used to operate a switch to de-energize the motor; at a given torque the pawls will ride over the balls and effect drive slip which is audible. The gear 24 meshes with a dished pinion 35 splined to a hollow shaft 36 that houses a spring-loaded clutch shaft 51 provided with upper and lower transverse pins 52, 53; the lower pin 53 carries one member 57 of a dog clutch, which member normally engages an associated clutch member 58 on a bevel wheel 60 coupled to the hand wheel 63. A gear 65 freely mounted on the pinion 35 meshes with a spur-wheel 66 on the shaft 67 of the electric motor 68, which latter is reversible and controlled by means including limit switches. The gears 24, 35 constitute a speed-reduction gear whilst gears 65, 66 form a speed-increasing means. The gear 65 embodies two diametrically opposed lugs 71 each supporting a saddle 72 that carries a cylindrical weight 74, the saddles being provided with followers that engage one member 86 of a dog clutch, which member is splined on the shaft 36 and mounted upon the upper pin 52 ; the other clutch member 87 is formed on a further spurwheel 89 freely mounted on the shaft 36 and meshing with a pinion 90 keyed to the motor shaft 67, which drive constitutes a speedreducing gear. When the motor is energized to actuate the valve the spur-wheel 66 drives the pinion 65, and the weights 74 are urged outward by centrifugal force whereby the followers lift the clutch member 86 into mesh with the clutch member 87 and, through the pin 52, shaft 51 and pin 53, the clutch member 57 is forced out of engagement with the associated clutch member 58. A yoke coacts with the weights 74 and limits outward movement of the latter. Upon de-energizing the motor the weights return to their inoperative position whereupon the spring 54 lowers the shaft 51 to disengage the upper dog clutch 86, 87 and engage the lower dog clutch 57, 58 to again connect the drive to the hand wheel 63. In a modification, the clutch shaft is dispensed with, the spring associated therewith being arranged externally of the hollow shaft to load a splined sleeve slidable on the latter, on each end of which sleeve is a dog clutch member. In another modification, the clutch 141, 142, Fig. 4, in the manual drive is normally engaged by three springs 158, only one of which is shown, each surrounding a rod 154 that connects a block 151 with the clutch member 142. When the electric motor rotates it drives the gear 160, shaft 125 and weight carrier 130 whereby outward movement of the weights 146 lifts the rods 154 to disengage clutch 141, 142 and engage clutch 159, 163 thereby driving the spur-wheel 162 and the gear 143. In a final modification, a spring 186, Fig. 6, engages clutch members 183 and 177, the latter being on the hand-driven bevel gear 178. Upon energizing the motor a pinion 192 is rotated so that each of six weights 198 move outwardly against its spring 207; the frustoconical faces 208 of the weights bear upon balls 209 to move them together with a thrust-plate 211 downwards against the spring 186 whereby the clutch 183, 177 is disengaged and another clutch 185, 174 is meshed. Since the clutch member 174 is part of a SHUT-wheel 171 the motor drives a pinion 175, spur wheel 171, a clutch sleeve 181, shaft 165, pinion 188 and gear 190.