GB770145A - Improvements in and relating to electromechanical control mechanisms - Google Patents

Abstract

770.145. Control of motors. COMPAGNIE DE PONT-A-MOUSSON. June 22, 1955 [June 24, 1954], No. 18087/55. Class 38(3) [Also in Groups XXIV and XXIX] Relates to control mechanism comprising a reversible electric motor and a worm and worm wheel, this mechanism being adapted to shift alternately in opposite directions a driven member, such as the gate of a valve, between two extreme positions. As shown, the motor M drives a worm 30 slidably keyed to a shaft 31 and held against a shoulder 34 by means of spring 35. The worm engages a worm wheel 21, and in one position of a control lever 29, dogs 20 on the worm wheel engage with dogs 19 on a slidable member 13 which is keyed to the load shaft 5. A spring 23 normally holds the dogs 19, 20, in engagement. When the gate of the valve enters into contact with its seat at the end of the valve-closing operation, or meets another obstruction, the wheel 21 stops rotating, the worm 30 urges the gate against its seat, and, incontinuing to screw against the wheel, travels along the shaft 31 and compresses the spring 35. A lever 59 is then pivoted about its axis so that cam 58 is moved to operate switch 50 and to interrupt the motor circuit. To open the valve the motor is reversed, and, initially, the worm 30 screws in the opposite direction until it abuts the shoulder 34. Teeth 55 on a plate 24 fixed to the shaft 5 drive a gear 54 and a pointer 56 for indicating the opening of the valve. A cam 51 rotates with shaft 52 so that, when the gate is opened, a switch 49 interrupts the motor circuit. If no electricity supply is available, the lever 29 permits operation of the gate by means of handwheel 18, shifting of the lever causing fork 27 to slide the member 13 upwardly against the action of spring 23 so as to separate the dogs 19, 20, and engage toothed ring 14 with gear 15. The member 15 is locked in its upper position by means of nose 36 which is adapted to engage hooks 37 or 38 disposed on spring-biased retaining pawls 39, 40; having a common pivot pin 41. The pawlsco-operate with lugs 44, 45, fixed on the driving shaft 31. If, at the beginning of manual operation, one of the lugs 44 or 45 is positioned in line with the pawl 39 or 40, this pawl being therefore retracted, the locking of the member 13 in its upper position is undertaken by the other pawl. When the motor M is started with the member 13 locked in its upper position, the lugs 44, 45, engage the pawls 39, 40, and release the member 13 which is spring-returned into the position in which the dogs 19, 20, are engaged.