GB1495911A - Breathing apparatus in particular for aircraft crew - Google Patents

Abstract

1495911 Breathing apparatus BENDIX CORP 23 Jan 1976 [19 Feb 1975] 02700/76 Heading A5T [Also in Divisions F2 and G3] An open-cycle respiratory apparatus comprises an exhalation valve 92 that includes a diaphragm 140 responsive to the breathing gas pressure in mask 14 via chamber 134 and the pressure in control chamber 142. A control valve 106 connects the mask pressure to the control chamber 142 via lines 84, 98, 96 during inhalation to maintain exhalation valve vent ports 136 closed by the diaphragm 140. During exhalation the control valve 106 opens to vent the control chamber 142 via a side port of chamber 88 and cause the diaphragm 140 to rise and allow the mask to be vented via ports 136. A main spring biassed diaphragm 18 controls the overall gas flow from cylinder 10. Respiratory gas is passed from the cylinder 10 to duct 52, 68 to cause diaphragm 50 to rise and admit the gas to the mask via ducts 70. filter 72 and tubing 74. The gas also acts upon the upper surface of the diaphragm 50 via restriction 60 and eventually causes it to close against duct 68. The mask is then placed on the face. During inhalation pressure is reduced in housing chamber 24 via tubing 84 and the main diaphragm 18 moves to cause knob 42 to pivot lever 44 and valve 82 away from duct 62. The reduced pressure in duct 62 then allows diaphragm 50 to open and gas to be inhaled. The increased pressure in the mask acts upon the control chamber 142 to maintain diaphragm 140 closed and eventually causes main diaphragm 18 to move back and allow valve 82 to close. Gas supply is then cut off by descent of diaphragm 50. If the mask pressure rises unduly valve 106 opens against its bias to vent via chamber 88. During exhalation the increased pressure resulting in chamber 24 causes knob 42 to actuate linkage 118, 102 to open valve 106 to vent the control chamber 142 and thus the mask. The pressure in chamber is thus reduced and valve 106 is re-seated.