GB898131A - Improvements in or relating to valve actuating mechanisms - Google Patents

Abstract

898,131. Gearing for stopping and starting machinery; positive clutches. ROTORK ENGINEERING CO. Ltd. June 30, 1960 [July 2, 1959], No. 22798/59. Addition to 842,581. Class 80 (2). [Also in Group XXIX] The valve operating mechanism of the parent Specification, comprising a clutch member selectively engaged with either a power drive means such as an electric motor or with a handoperated drive means, the clutch member being maintained engaged with the hand-operated drive means against spring bias by a pawl pivotally mounted on the clutch member and abutting eccentrically the shaft of the power means, is modified by mounting the power drive means engaged by the pawl away from the shaft of the power means although in such a manner as still to be rotated thereby. In one form, a clutch sleeve 23, Fig. 2, is splined upon a shaft 17 connected to a valve operating shaft 6, and is normally biased by a spring 27 to engage peripheral slots 29 formed in a flange 28 at its lower end with pins 30 fast in a driving wormwheel 5, hand operation of a lever 32 having a yoke 31 formed with fingers engaging a circumferential groove 33 in the clutch sleeve sliding the latter against the bias of its spring to disengage the clutch sleeve from the worm-wheel and instead engage clutch dogs 24 with corresponding dogs on a hand wheel 22. The clutch yoke 31 carries at one side a transverse bar 34, Fig. 4, upon which pivots a pawl 35, Fig. 6, biased by a spring 36 so that in the position described, the flat end 37 of the pawl engages a thrust ring 20 carried fixedly by a surrounding housing. Accordingly, the clutch sleeve 23 is held in engagement with the hand wheel 22 for manual actuation of the valve. If, however, the worm-wheel 5 is rotated, the pawl 35 is turned against the bias of its spring 36 and the clutch spring 27 slides the sleeve 23 out of engagement with the hand wheel 22 and instead engages the circumferential recesses 29 therein with the pins 30 in the worm-wheel. The lost motion between the circumferential recesses 29 in the clutch sleeve 23 and the pins 30 on the worm-wheel ensures that operation of the valve by the electric motor, 2, is commenced with a hammer blow. In the form shown, the wormwheel 5 is meshed by a worm 4 upon a shaft 3 axially slidable in the housing containing the mechanism against the bias of two stacks of centralizing Belleville springs 10, the shaft being the armature shaft of an electric motor 2. Alternatively, an hydraulic or pneumatic motor may be employed. When the worm-wheel 5 reaches the end of its trayel on closure or opening of the valve, the worm 4 tends to screw therealong against the bias of the Belleville springs 10, and acts through a pin 14 engaging a grooved sleeve 16 fast upon the shaft to open a switch and cut out the motor. In another form, a clutch sleeve 55, Fig. 10, is splined upon a shaft 54 and is slidden axially by pins 61 engaging a groove 62 and carried in the arms of a yoke 59 pivoted by a hand lever 60, Fig. 11, a pawl 64 pivoted on one of the yoke arms being biased by a spring 65 so that its end engages a ring-shaped plate 66, carried by a gear 50, to prevent engagement of clutch dogs 56 on the sleeve with clutch dogs 57 upon the gear 50. A spring 63 surrounds the clutch yoke and tends to cause engagement of the dogs 56, 57. Instead, clutch dogs 56 at the other end of the clutch sleeve 55 are engaged with corrsponding dogs 58 on a gear 53 meshed by a gear 52 turned by a hand wheel. An electric motor 41, Fig. 9, drives a shaft 40 carrying at its end a gear 49 meshing the gear 50, switching on the motor causing the latter gear to rotate and hence to pivot the pawl 64 against the bias of its spring 65, allowing the spring 63 to turn the clutch yoke 59 thereby disengaging the clutch dogs 56 from the dogs 58 on the gear 53 and instead engage the clutch dogs 56 with the clutch dogs 57 on the motor-driven gear-wheel 50. A pin 68 on the pawl 64 now engages a guide plate 67 fast with the mechanism housing, so that the pawl is held clear of the rotating gear-wheel 50 and wear is prevented. The shaft 54 upon which the clutch sleeve 55 is splined is formed with a worm 48 meshing a worm-wheel 45, Fig. 8, and is axially slidable but biased to a central position by two stacks of Belleville springs 47. The worm-wheel 45 is secured to a thrust sleeve 69 into which is screwed a nut 75 upon a valve operating shaft 46. A lost-motion coupling may be provided between the wormwheel 45 and the shaft 46. Two rings 70 are welded upon the thrust sleeve 69 and coact with a ball thrust bearing 71 between flanges 72, 74 of the valve operating shaft.