Development and Testing of An Aspirated Airbag Inflator Module

摘要

Conventional airbag inflators use high pressure and high temperature combustion gas to inflate the bags. The energy transfer efficiency is low from the view-point of engineering, because high temperature high pressure gas must be cooled, while low speed gas has to be accelerated to a certain criteria. Aspirated inflator improves these processes by introducing large volume of ambient air to the inflator through a well-designed linear nozzle, the energy transfer is efficient, and the amount of gas generants used is also reduced drastically. Low mixed gas temperature enables utilizing light-weighted plastic films as the bag materials. In this work, an aspirated inflator is designed and tested. Simulations of different variables that may affect the aspiration effects, such as pressure, temperature, changes of input gas, nozzle geometry, air entrance curvature, as well as the flow field of mixed gas in the mixing zone are calculated. The results make the inflator design easier, and no backflow of mixed gas may occur. Calculations on the effects of both ambient gas temperature and pressure are also studied. The aspirated inflator introduces as much as 4 times of the combustion gas from the ambient, and the temperature of mixed gas is lower than 170℃. The lower temperature realizes the usage of plastic film as the bag material, and makes the bag material cheaper and easier to be manufactured. Deployment tests of the aspirated inflator airbag module show that the 104 liters capacity bag is fully inflated within 68 msec and keeps a period of time before it starts venting. Excellent aspirating performance is also contributed to the well-designed one-way valve set nearby the air entrance, which effectively inhibits the outrage of mixed gas from the inflator.