Patent GB-796100-A (GB)
Title: Improvements in or relating to breathable gas regulator
IPC: A62B9/02
Filed: 1955-04-26
Abstract: 796,100. Respiration apparatus. GARRETT CORPORATION. April 26, 1955 [May 3, 1954], No. 11994/55. Class 81 (2). [Also in Group XXIX] A regulator for respiration apparatus has a respiration responsive movable wall, a gas supply valve opened by actuating means responsive to movement of the wall and means responsive to changes in pressure of gas upstream of the valve to maintain uniform the breathing force required to open the valve. The regulator 11 is connected to a source of breathable gas in a tank 12 and to a mouthpiece 13 by way of an inhalation conduit 14. Exhaled gas is conducted by an exhalation conduit 15 to the regulator 11 from which it passes to the surrounding fluid medium. On inhalation a reduction of pressure created in a chamber 26 of the regulator 11 causes a diaphragm 25, which is exposed on one side to the ambient fluid and forms one wall of the chamber 26, to move inwardly of the chamber 26 and by means of levers 116 to raise a valve member 102 from its seat 100 so that gas can flow from the tank 12 to a second chamber 44 in the regulator 11 and thence to the mouthpiece 13. Expired gas passes from the exhalation conduit 15 into the first chamber 26 of the regulator 11 so that the diaphragm 25 moves outwardly of the chamber 26 and the valve 102 shuts off the gas supply. Exhalation valve 36, which controls holes 35 in a bushing 32 in the diaphragm 25, opens to allow expired gas to be vented to the surrounding medium through openings 23 in the regulator cap 21. Breathable gas leaving the tank 12 flows through a shut-off valve 50 and through the body of the regulator 11 to a chamber 57 surrounding a member 63 slidably disposed in a bore 65. Gas then passes through passages 76, 77 in the member 63 and is normally of sufficient pressure to lift a reserve valve 80 from its seat 78 in the member 63 against a spring 81 so that gas can flow by way of a passage 87 to an annular recess 88 between a piston 90 and a bore 95 in which it slides. Gas flows from the recess 88 through passages 97, 98 in the piston 90 towards the valve 102. The valve 102 is urged by a compression spring 103 towards its seat 100 which is formed in the piston 90. Another compression spring 111 urges the piston 90 away from the valve 102 and against a pressure created by the flow of gas acting on the surfaces of the annular recess 88. A fulcrum supporting member 107 having holes 110 through which gas passes to the second chamber 44 is secured to the piston 90 and surrounds the springs 103, 110. Fulcrum members 112 are provided on the fulcrum supporting member 107 for the levers 116 each of which bear at one end against a plate 27 secured to the diaphragm 25. As the pressure of gas from the tank 12 falls during use, the piston 90 and the fulcrum members 112 gradually move away from the valve 102 and the diaphragm 25, respectively, due to the fall in pressure against the surfaces of the annular recess 88. This ensures that as the gas supply is reduced, the breathing effort required to move the levers 116 to open the valve 102 remains constant. The reserve valve 80 is disposed so that, when the amount of gas remaining in the tank 12 falls below a predetermined amount, the gas pressure is insufficient to unseat it. The member 63 is then moved away from the reserve valve 80 by rotating a lever 67 over a cam portion 82 so that the gas remaining may then be used. Reference has been directed by the Comptroller. to Specification 758,418.