Overpressure limiting hybrid inflator

摘要

A dual stage hybrid inflation device includes a first stage gas source (110) comprising a pressurized gas (116) stored in a first stage pressure vessel (114) and a second stage gas source (112) comprising a pyrotechnic gas generator (130) having a gas output directed into the first stage pressure vessel (114). The first stage pressure vessel (114) is in fluid communication with an inflatable device such as an aircraft emergency evacuation slide via an externally actuated valve (148) upstream of a pressure actuated valve (150) such as a rupturable diaphragm. A control circuit provides a signal to the externally actuated valve to begin a flow of gases from first stage pressure vessel (114) to a chamber on the upstream side of the burst diaphragm (160). The control circuit also sends a signal to the squib that initiates the pyrotechnic second stage gas source (130). As the pyrotechnic gas generator of the second stage gas source bums, the hot gaseous products of the second stage gas source mix with the pressurized gas (116) stored in the first stage pressure vessel (114) a predetermined time after the externally actuated valve (148) opens. At low temperatures, the pressure actuated valve (150) prevents the flow of gas from the first stage. This allows the hot combustion products from the second stage gas source to mix with the pressurized gas in the first stage pressure vessel (114), thereby heating the pressurized gas (116) until sufficient pressure is developed in the first stage pressure vessel (114) to open the pressure actuated valve (150). At high temperatures, however, pressure in the first stage pressure vessel (114) is above the threshold pressure of the pressure actuated valve (150). Accordingly, when the externally actuated valve (148) is opened, the pressure actuated valve (150) opens immediately, thereby allowing the pressure in the first stage pressure vessel (114) to drop to a safe level before the pyrotechnic gas generator (130) is initiated.