Patent GB-824846-A (GB)
Title: Liquid level control valve
Inventor: DAVIES ROBERT HENRY
IPC: F16K31/34
Filed: 1956-02-01
Abstract: 824,846. Fluid-pressure servomotor control systems; valves. PARKER-HANNIFIN CORPORATION, [formerly PARKER APPLIANCE CO.]. Feb. 1, 1956, No. 3194/56. Class 135. A rubber fuel tank houses a main valve 13, Fig. 1, and a pair of pilot valves 11, 12 in a casing 55, the pilot valves being of the same construction and each actuated by a float 73 mounted at the same or different levels; the valve 13 and casing 55 are bolted and vulcanized to the bottom and top walls, respectively, of the tank. The main valve comprises a flat seat 25 connected to the valve body 27 by ribs 26 spaced about the seat 25, the body 27 housing primary and secondary diaphragms 31, 32, the former being attached to the valve closure member 35 which incorporates a rubber seal 36; the chamber 40 between the diaphragms leads to the pilot valve 12 by a tube 50 whilst the chamber 52 above the secondary diaphragm 32 is connected to both the other pilot valve 13 via a tube 51 and the inlet 20 by way of a port 91 and passages 92, 93. When the main valve is closed and the tank is not full the pilot valves are open due to the lowered position of the float 73, but upon admitting pressure liquid into the inlet 20 the member 35 is unseated against its spring 45 and liquid passes into the tank interior between the ribs 26; at the same time liquid flows into the chamber 40 through an orifice 97 in the central element 38 of the primary diaphragm 31, the liquid passing from the chamber 40 to the pilot valve 12, the closure member 62 of which is unseated, so that the liquid enters the tank via an opening 67 in the casing 55, the liquid emptying from the chamber 40 faster than it can enter it due to the smallness of the orifice 97 so that the pressure in chamber 40 is less than that in the inlet 20; at the same time liquid in the inlet 20 passes through port 91, some entering the chamber 52 and the remainder entering the tank via the pilot valve 13. As before, the pressure in chamber 52 remains less than that in the inlet 20. The floats 73 lift with rising liquid level and close the pilot valves 11, 12 whereupon the pressure in chambers 40, 52 approximates to that in the inlet 20. The liquid in chamber 40 acts on the diaphragm 31 over an area greater than that of the member 35 and causes the latter to seat in opposition to the liquid in the inlet 20 acting on the underside thereof; the upward force on the diaphragm 32 caused by the liquid in chamber 40 is counterbalanced by the liquid in chamber 52 so that the diaphragm 32 is held in contact with the primary diaphragm 31 by the spring 45. The apparatus is so arranged that the member 35 will seat should either of the diaphragms become ruptured, the floats logged or the pilot valve stuck. In a modification, the liquid from the inlet 112, Fig. 6, enters the primary chamber 130 through clearance 140 between a stud 138 depending from the secondary diaphragm 119 and the bore of a hollow nut 123 fixed to the primary diaphragm 118. Liquid enters the secondary chamber 132 through the stud 138 which has an orifice 141 at the entrance thereto. The spring 131 may be disposed between the diaphragms or in the secondary chamber. In another modification, the main valve is designed to be located outside the tank and in consequence the main outlet is axially aligned with the inlet and arranged to be connected to the tank by a pipe.