Is it possible to control airbag pressure?

摘要

An external airbag system in which the airbags deploy outside the vehicle before a collision has been proposed. The developed system uses four airbags that are mounted inside the front and rear bumpers and both side doors. The problem with this system is how to control the inner pressure of the airbags immediately after collision so as to absorb as much of the crash energy as possible. To solve this problem, a model of the variation in the inner pressure of the airbag is given from the standpoint of fluid dynamics. A simulation is then performed by changing the size of the outlet area and the crash load in the airbag system. According to the experiment, the model is basically approximated by a second order transfer function in which the input is the crash load and the output is the resultant inner pressure of the airbag. A crash test is then implemented at a vehicle speed of less than 50 km/h. In this test, the inner pressure change is measured during a collision into the truck tires for several sizes of airbag outlets. The experimental results show that a damping ratio of 0.6 immediately after a collision helps to absorb the crash energy if the outlet area of the airbag is adequately designed. The results also suggest that it may be possible to predict the inner pressure change at high speed crashes over 50 km/h.