Patent GB-541717-A (GB)
Title: Improvements in or relating to drives for valves and the like
IPC: F16K31/05
Filed: 1940-04-08
Abstract: 541,717. Valves. IGRANIC ELECTRIC CO., Ltd. April 8, 1940, No. 6311. Convention date, April 10, 1939. [Class 135] A screw-and-nut mechanism for actuating a valve is capable of being driven by a motor M, Fig. 18, or a hand-wheel 104 and is constructed so that the operating-mechanism is disconnectible as a unit from the yoke 2 of the valve, and the screw 3 moves in the yoke 2 and when the valve is pressed on its seat a limit switch 75 is operated to break the circuit of the motor M. A limit switch 95 is also operated when the valve reaches its open position. The motor M drives by reduction gearing a shaft 46 and worm gearing 40, 26, a sleeve 29 which is connected by tongues and slots to a sleeve 35 which drives by tongues and slots a nut 4 for actuating the screw 3. The nut 4 is supported by combined radial and thrust bearings 7, within a sleeve 8, which tends to move upwards as the nut drives the screw downwards, and vice versa. The upward movement is resisted by a plate 61 which is pressed downwards by a number of springs 60 arranged between the plate 61 and a plate 62. When the valve closes on its seat the nut 4 and sleeve 8 moves upwardly out of normal position against the action of the springs 60 and the plate 61 is raised to actuate the cut-out switch 75, which is mounted on an insulating terminal board 76 in the upper compartment 21 of the casing 15 to which is fitted a removable cover 20 permitting access to the terminals and to screws 63 which adjust the action of the springs 60. The "open" limit switch 95 is indicated in the diagram Fig. 18 which shows the circuit arrangement for the valve drive, and comprises a contact normally closed by a spring but adapted to be opened by a cam on a shaft 102, Fig. 3, geared to the shaft 46 of the worm 40. The shaft 46 may be operated by a hand wheel 104 which operates a gear 105 geared to a pair of gears 108, 109, Fig. 8, which can be brought into engagement with a gear 107 on the shaft 46 by rotating the wheel 104 in the direction of the arrows A, B. The gears 108, 109 are carried by a pivoted yoke 110 which is mounted so as to be capable of receiving a limited angular movement against the action of a spring 124 owing to its frictional engagement with the wheel 104, but a locking member including a sliding sleeve, which engages a recess 136, Fig. 10 (not shown) in the yoke 110, prevents actuation of the wheel 104 when the motor M is in action. The sliding sleeve acts as a locking-member, and.is operated by the centrifugal action of balls on a conical surface attached to the sleeve. The yoke 110 may also be controlled by a latch mechanism comprising a lever 138 with a pin 145 which can engage stop projections 146 to prevent actuation of the yoke. An electromagnet 148 with an armature 149 may operate a latch for holding the latch mechanism 138 in released position. This electromagnet is energized when the motor M is being driven so that the hand-wheel drive is locked when the motor circuit is closed. The yoke 110 when moved to throw-in the handcontrol operates a switch 155, Fig. 18, which breaks the motor circuit. The motor M is shown as of three-phase alternating current type, and the power from the lines L1, L2, L3 is controlled by a pair of three pole electromagnetically operated reversing switches C, O, with normally open contacts C<SP>1</SP>, O<SP>1</SP>. "Open" push buttons 166, 167 and a " close " push button 168 control the starting and stopping of the motor in conjunction with the controls referred to above. The screw 3 may be fitted with nuts 182, Fig. 14, for operating an auxiliary valve 170, Fig. 14, which is used in connection with apparatus for cracking oils. The nuts operate a link 184 connected to a lever on a shaft 173 which transmits motion through an adjustable spring connection to a lever 175 which depresses the spindle 172 of the valve. The shaft 173 operates an upper limit switch to close the main valve in place of the limit switch 95. Specification 541,743 is referred to.