GB850338A - Power operating mechanism for fluid control valves - Google Patents

Abstract

850,338. Friction clutches; change-speed control. PHILADELPHIA GEAR CORPORATION. Oct, 3, 1958 [April 21, 1958], No. 31603/58. Class 80 (2). [Also in Group XXIX] The threaded stem- 12, Fig. 1, of an electric motor actuated gate-valve 11, engages a nut 16 journalled in a casing 15 but restrained against axial motion, the casing 15 supporting a box 17 containing limit switches for stopping the electric motor 35 at the end of the valve opening and closing movements. The valve may be manually operated by a wheel 18 and a declutching handle 19 that prevents rotation of wheel during power actuation. Within the casing 15 is an input gear 21 on a worm shaft 22 that drives a worm gear 23 integral with the nut 16 ; shaft 22 is provided with another worm 25 driving a gear 26 which operates an electric switch 27 having wires 67, 68, 69 connected thereto. Gear 21 is driven from the motor 35 via a two speed gear 31 that comprises a driven shaft 44, Fig. 3, and a countershaft 43, the latter having an input gear 33 fixed thereon and the shaft 44 supporting the output gear 32; relatively small and large gears 46, 47 are fixed to the countershaft 43, which gears mesh with relatively large and small gears 48, 49 journalled on shaft 44. Each gear 48, 49 may be connected to the drive shaft 44 by a normally disengaged multiple disc clutch 50, 51, respectively. Two stationary housings 60 encircle the shaft 44 and each contains a coil 60a, which when energised moves ar armature 61 to clutch the associated gear to, the shaft 44. Terminals 65, Fig. 1, are connected to a source of power, which terminals are joined by wires 66, 67 to the coils 60a and switch 27, respectively, and since the latter is in the drive means of the valve the coil 60a associated with clutch 50 is energised to cause the drive to the valve to be transmitted through low-speed gears 46, 48 during the initial valve opening movement, contined rotation of the switch 27 then energises the other coil 60a so that the drive is taken through the higher-speed gear 47, 49. In this manner an increased force is applied to the valve during the initial opening movement and surging or " liquid hammer " is prevented. The reverse sequence occurs during valve closure. Switch 27 energises only one coil 60a at a time and the point at which one clutch is engaged and the other disengaged is adjustable. In a modification, the low-speed clutch 50 is normally spring engaged so that the valve can still be operated should there be a failure of the coil 60a. Both coils are mounted in a common body and the armatures are disposed adjacent the latter, the coils being simultaneously energised. The mechanism may be applied to any type of fluid-controlling valve.