GB1417923A - Respirator - Google Patents

Abstract

1417923 Respirators AIRCO INC 25 July 1973 [25 July 1972] 35346/73 Heading A5T [Also in Division F2] A respirator for connection to a source of oxygen pressure comprises a bellows container 50, an expansible bellows 52 within the container 50, a valve 26 for introducing the oxygen into the container to collapse the bellows and thereby deliver a predetermined volume of at least oxygen to a patient, means to expand the bellows and thereby remove oxygen from the container and introduce gas into the bellows. Valve 26 controls the supply of oxygen to a venturi 28 and also to a fluidic circuit 36. The flow to the venturi is controlled by valve 44 in control duct 42, and passage 48 connects the venturi chamber 46 with the container 50. The bellows 52 is freely suspended within the container 50 and sealed against the upper surface. A weight 115 located in the bottom of the bellows assists in expanding the bellows, thereby driving oxygen from the container 50 via valve 54 to mixer 68. Oxygen also flows via passage 48 to chamber 46, into conduit 70 via valve 102 and thence to mixer 68. In mixer 68 the gas is mixed with air drawn in via conduit 74, excess oxygen exhausting via pipe 72. The mixture from mixer 68 is drawn into the bellows as the bellows expands. A signal from the patient to the fluidic circuit 36 is relayed to valve 26, causing it to open and pressurise venturi 28 and container 50 via passage 48 and also to close valve 54. The increased pressure within the bellows container 50 causes the bellows 52 to collapse, forcing the gas mixture through conduit 56 to patient 58, the volume delivered being governed by the permitted expansion of the bellows as controlled by string 100 and spool 101. The weight 115 comprises a magnet oriented so that in the collapsed condition, like poles on weight 115 and magnet 113 in switch 112 repel, magnet 113 moving upward to close duct 114, thus sending a signal to part D off fluidic circuit 36 which changes its mode from inhalation to exhalation. The oxygen mixer 68, Figs. 2, 3, 4 (not shown), proportions the oxygen and air by varying the opening for each gas, the total area remaining constant. The oxygen and air inlet ports (164) and (166) respectively are connected to conduits 70, 74 respectively at approximately atmospheric pressure. A projection (170) within the port (168) defines the area (171) divided by projection 173 into two areas (A 1 , A 2 ) Fig. 3. Rotation of shaft (174) moves baffle (172) to vary areas (A 1 , A 2 ) the total area remaining constant, giving oxygen concentrations varying between 21% wt and 100%. Manual or automatic operation is possible, and alarm circuits are described for low gas pressure and failure to cycle.