Patent GB-520771-A (GB)
Title: Improvements in or relating to valve controlling means
IPC: F16K31/00
Filed: 1938-11-01
Abstract: 520,771. Valve-actuating mechanism. KOCKUMS MEKANISKA VERKSTADS AKTIEBOLAG. Nov. 1, 1938. Nos. 31643 and 31644. Convention dates, Nov. 2, 1937, and Feb. 22, 1938. [Class 135] A control mechanism for opening and closing a valve connecting a source of pressure to an alarm or other apparatus comprises a control member for opening or closing the valve, a releasable stop member for holding the control member with the valve in the closed position, an actuating or energy storing device for moving the control member either to open or to close the valve and a restoring device, such as a diaphragm mechanism subject to the pressure in the outlet conduit for restoring the mechanism to its initial position on the completion of a cycle. When the valve has been opened it remains open until a second stop member for the control member is released. In the form shown in Figs. 1, 2, a plunger type of lift valve 23. closing in the direction of flow and operated by a push rod 32 against an adjustable loading spring 24 is arranged in a casing 21 having its inlet 26 connected to the vessel (not shown) and its outlet 27 connected by a conduit 29 containing a reducing valve 30 and a check valve 31 to alarm apparatus 28. A three-armed lever 36 pivoted at 37 has one of its arms 40 connected to a spring 38 which tends to move the push rod 32 in the valve opening direction and is held in the position shown by a stop 41, Fig. 2, on an armature 42 pivoted in a vertical plane so that when its associated electromagnet 43 is energized by closure of a switch 45 the armature is attracted against the force of a spring 47 and the stop 41 moves into the path of a recess 49 in the lever 36. This releases the lever 36 which under the action of the spring 38 opens the valve 23. A further stop 79.on the armature arrests the lever 36. When the switch 45 is opened, the armature is retracted and the stop 79 is moved to allow the lever 36 to open the valve 23 further. The lever 36 is also engaged by a push rod 57 operable by a diaphragm 51 exposed on its upper side to atmospheric pressure through an aperture 53 and on its underside to the pressure on the outlet side of the valve 23 under the control of a shuttle valve 59. The latter operates in a cylindrical chamber 58 connected with the lower diaphragm chamber by a port 54 and closed at its ends by ported plugs 60, 61 which form seats for valve members 65, 66 of soft material. The passage 62 in the plug 60 is connected with the inlet or outlet side of the reducing valve 30 by a conduit 55. A rod 64 loaded by a blade spring 67 to move to the right moves with clearance in the other plug passage 63. The blade spring 67 is engaged by a pivoted arm 68 loaded by a spring 70 and having a projection 71. The latter carries a pin 72 engaged on opposite sides of the projection by the slant-ended prongs of a bifurcated arm 73 pivoted on the lever 36 and urged to the left by a spring 75 anchored to an arm 76 rigid with the lever 36. When the lever 36 is first released, the prongs of the arm 73 press on the pin 72 so that the rod 64 presses against the valve 59 and prevents pressure fluid from entering the lower diaphragm chamber. After the switch is opened and the lever 36 is released further, the ends of the pin pass through recesses in the prongs of the arm 73 so that the spring 70 cannot resist' the spring 67 and the fluid pressure tending to move the valve 65 from its seat. Pressure is then admitted to the lower diaphragm chamber so that the push rod 57 moves the lever 36 which rides past the stop 41 and tensions the spring 38 again. Simultaneously the valve 23 closes and the pressure in the diaphragm chamber leaks away slowly. When the lever 36 is raised by the diaphragm, the ends of the arm 73 pass above the pin 72 and subsequently descend on its opposite side so that the parts are once more in the initial position. In the modification shown in Fig. 3, the lever 36a acts on the valve opening rod 32 through a spring-pressed push rod 81 and is urged in the valve opening direction by an adjustable spring 38a acting through a slotted rod 57a which at its lower end abuts a diaphragm 51a. The lever 36a is pivoted to a lever 83 itself pivoted at 84 and restrained by a pivoted catch 85. The latter is loaded by a spring 87 and is released by a pivoted armature 42a to which it is connected by a link 89. The upper end of the lever 83 has a cam 100 and in its end positions prevents a spring-loaded control valve 97 from closing by means of a lever 96. When the magnet circuit is closed, the catch 85 is released and the valve 21 opens so that pressure medium passes to the alarm apparatus as in the previous embodiment. The released spring 38a also forces the lever 83 past the right hand end of the catch 85. The same movement of the lever 83 first closes and then opens the valve 97 so that pressure fluid from the outlet side of the valve 21 passes through conduits 55a, 56a to the diaphragm chamber 52a and tensions the spring 38a again. When the magnet circuit is opened again, the catch 85 is released at its right hand end and the levers 83 and 36a are returned to their initial positions in which they are held by the left hand end of the catch 85, by the spring 82. Simultaneously the valve 21 is allowed to close and the lever 96 opens the valve 97. Another embodiment, Fig. 4, has a valve 23b closed by the pressure of the fluid and carried by a rod 32b having an adjustable screw 135 at its lower end. The armature 42b of the electromagnet 43b is pivoted at 46b and urged away from the magnet by an adjustable spring 47b. The lower end of the armature lies between adjustable screws 131, 132 carried respectively by links 110, 111 of toggles 109, 110 and 111, 112. The links 110, 111 are pivoted at 116, 118 respectively to a lever 108 connected at an end to a spring 126 and at an intermediate point 123 to a link 113 having a fixed pivot 122. In their stable positions, the toggle links 109, 112 abut adjustable screws 124, 125 respectively. The link 109 has a fixed pivot 115 and the link 112 is connected at 119 to a lever 114 operable by a diaphragm 51b in a casing 50b connected to the outlet side of the valve 23b by a pipe 55b. When the magnet circuit is completed, the armature engages the screw 131 thus breaking the toggle 109, 110. A spring (not shown) connecting the lower end of the link 109 to the upper end of the link 111 then maintains the toggle 111, 112 firmly in its stable position. The spring 126 then moves the lever 108 about the pivot 118 so as to raise a rod 81b into contact with the screw 135 and open the valve 23b. The rod 81b is guided in a bracket 136 carying an adjustable stop 107 for the armature 42b. Pressure medium then flows to the alarm apparatus and also to the diaphragm casing 50b. The diaphragm 51b then operates through the lever 114 to move the toggle 111, 112 bodily upwards. The lever 108 therefore pivots about the point 123 so that the toggle 109, 110 is almost straightened and spring 126 is tensioned again. The tension of the spring connecting the links 109, 111 is simultaneously relieved. On opening the magnet circuit, the armature 42b engages the screw 132 so as to break the toggle 111, 112. The straightening of the toggle 109, 110 is completed by the spring between the links 109, 111 when the toggle 111, 112 is moved by the pressure on the diaphragm. At the same time the lever 108 moves about the pivot 116 and allows the valve 23b to close. The pressure on the diaphragm is then relieved and the spring between the links 109, 111 returns the toggle to its straight position. In a further embodiment, Fig. 5, the valve 23c opens in the direction of flow and its actuating rod 32c is pivoted to a lever 108c in turn pivoted to the links 110c, 111c of toggles 109c, 110c and 111c, 112c. The link 110c carries a stop 144 engageable by a pin 145 carried by the armature 42c and passing through an adjustable stop 124c. The armature 42c also carries a bent rod 146 having a stop 149 which can press a rod 150 through another adjustable stop 125c so as to break the toggle 111c, 112c at its point 120c. On energizing the electromagnet (not shown),'the pin 145 breaks the toggle 109c, 110c so that fluid pressure opens the valve 23c and the rod 32c descends as far as a stop 142c. A spring 138c maintains the toggle 111c, 112c straight. The outlet pressure is then admitted to a diaphragm 51c which through the straightened toggle 111c, 112c and the lever 108c straightens the toggle 109c, 110c again, tensions a spring 126c and releases the tension of the spring 138c. When the magnet circuit is opened again, a spring 151 moves the stop 149 so as to break the toggle 111c, 112c, this being aided by the pressure on the diaphragm 51c and by the spring 126c. The spring 138c completes the straightening of the toggle 109c, 110c and the lever 108c is moved upwardly about the pivot 116c to close the valve. The spring 138c straightens the toggle 111c, 112c when the pressure leaks away from the diaphragm. According to the Specification as open to inspection under Sect 91, the toggles are prevented from breaking simultaneously by a pivoted member 141, Fig. 8 (Cancelled), which is always in the path of one of the arms 139, 140 on the respective.links 110, 111 of Fig. 4. This subject-matter does not appear in the Specification as accepted.