Patent GB-447830-A (GB)
Title: Improvements in or relating to fluid-pressure operated stop valves, bye-pass valves and means for controlling such valves
IPC: F16K31/363
Filed: 1934-11-22
Abstract: 447,830. Valves. DEWRANCE, SIR J., 165, Great Dover Street, Southwark, London. Nov. 22, 1934, No. 33611. [Class 135] Relates to the fluid-pressure operation of a main stop-valve and an associated equalizing byepass valve, particularly for controlling high-pressure steam in a power station, the desired sequence of pressure supply to the motors operating the valves being controlled by a single multiple-way valve-unit through three pipe lines, two of which are branched and contain non-return valves, and the motors wholly exhausting direct to the atmosphere. The main valve is drained before it is opened, and is adapted for immediate hand operation. The main stop-valve 1, Fig. 1, is operated by a reversible compressed air rotary or reciprocating motor 2, and the valve 3 in the byepass 3b, 3c is operated by a piston and cylinder motor 4, both motors exhausting direct to atmosphere. The main valve chamber is vented to the inlet side through a pipe 3a and the hood of the byepass valve. The control valve 6 directs the air supply at 5 in turn to (i) a pipe 7 opening the byepass valve 3 ; (ii) a pipe 8 opening the main valve 1 and, by a branch 8a and non-return valve 8b, closing the byepass valve (a tappet 16a, Fig. 6, connected to the main valve spindle shuts off the air supply to the motor 2 at valve 10 as the main valve reaches fully open position, as described in Specification 371,541) ; (iii) a pipe 9 closing the main valve and by a branch 9a and non-return valve 9b ensuring closure of the byepass valve (tappet 16a cuts off motor 2 at valve 10a when the main valve is almost fully closed). The main valve is drained by a cock 12 which must be opened before the control valve 6 can be operated. On turning the hand-wheel 12c of the drain-cock, a collar 12d, Fig. 2, on its operating spindle 12b removes the end of a spring-pressed lever 15 from a slot 13k in a drum 13m on the spindle 13 of the control valve 6. The control valve 6 consists of three mushroom-headed valves, Figs. 4, 5, (not shown), one for each of the pipes 7, 8, 9, lifted against the action of springs by a handoperated cam-shaft 13, the cams acting on the valve spindles through pivoted arms. A catch consisting of a spring-pressed ball snaps into recesses in a disc on the cam-shaft to hold the control valve in any set position, indicated by a pointer 13i. A spring plunger 13j on the control handle co-operates with fixed cams 14b to prevent reverse movement of the control valve. The handle may also be locked against unauthorized operation. Electric lamps inside a casing 14a, illuminated by contacts on the valves, indicate the positions of the main and byepass valves. The main valve spindle is in two parts 17, 17a, Fig. 6, swivelled together at 18, the upper part being screw-threaded at 17d. The lower part 17 is guided by a spider 16 co-operating with pillars 1c. The motor 2 by a worm drives in either direction a worm-wheel 20c having pins 20d engaging (with lost motion to enable the motor to pick up speed) lugs 21b on a sleeve 21 keyed on a nut 20 rotatable between fixed end bearings and actuating the valve spindle, the portion 17a of the spindle being automatically locked against rotation whilst the motor is in use, by lugs 1j referred to below. For hand operation the spindle 17a is rotated by a wheel 22, the nut 20 being locked against rotation by its engagement with the irreversible worm-drive 20c. The wheel 22 has a cam surface 22b which lifts a spring-pressed spider 24 to remove arms 24a depending therefrom clear of the fixed lugs 1j, and thereafter the wheel rotates the spindle through the spider and a keyed sleeve 23. A governor may be mounted on the worm or motor shafting actuating valves in the supply pipes 8, 9 of the motor. Or baffles in the pipes may be moved mechanically at a given part of the main valve stroke to increase the power as required. For instance, the movable member of the cut-off valve 10a actuated when the main valve is closing, has a hollow spindle 10b, Fig. 8, through which passes a plunger 10c carrying a baffle washer 10d. On actuation by the tappet 16a, the baffle is moved to increase the area of the passage until the valve 10f is closed. Where a rotary air motor is used, in which the inlet port for one direction of rotation becomes the exhaust port for the other direction, an automatic shuttle valve, Fig. 9, is employed comprising two large discs 25, 25a, which close one port, as 29, and exhaust the motor through passage 30 direct to atmosphere at 28, while opening the other port 29a and sealing it from atmosphere. Cups 25b, 25c on the spindle assist in the blowing over of the shuttle. Alternatively, a tappet on the main valve spindle may actuate the shuttle. The byepass valve, Figs. 10, 11, (not shown), with faces at a slightly less distance apart than the seatings, and with a balancing tail-rod, may be hand-actuated by a rack-andpinion. The cylinder of its operating motor 4 is provided with adjustable needle valves in the inlet passages above and below the piston, to control the speed. These needle valves have each an adjustable axial leak to provide the exhaust direct to atmosphere. Specifications 282,137 and 300,807, [both in Class 135], also are referred to.