Current research in the automotive industry is focused on lightweight, intelligent, and safe designs. In particular, passenger safety requirements are continually becoming more demanding. Automobile companies seek to maximize passenger safety by considering it of primary importance in the initial development stage of the vehicle’s body design, with attention to characteristics such as body stiffness and airbag modules..
Near the turn of the millennium, airbags were classified as either depowered airbag systems, which are single-stage inflation systems with the inflator pressure “depowered” by approximately 30%, or smart airbag systems, which use dual-stage inflators.
Many studies have reported that the depowered airbag systems fail to fulfill the airbag performance requirements for out-of-position (OOP) adults, and the smart airbag systems fail to fulfill the airbag performance requirements for OOP small adults or children in car crashes. To overcome these safety problems associated with conventional airbags, the U. S. Federal Motor-Vehicle Safety Standard 208 (FMVSS 208) requires a low risk deployment (LRD) airbag system designed to protect OOP passengers in car crashes.
This study’s objective is a robust design of a LRD passenger airbag system that ensures safety through airbag deployment with a passenger protection wrap (PPW), which adds a wrap to the airbag to ensure pressure dispersion. The PPW reduces cushion impact force to passenger by ensuring pressure dispersion. A series of static test were conducted to demonstrate the proposed system using FMVSS 208 test procedures. The test results showed that the proposed passenger airbag satisfies the criteria established by the FMVSS 208.
In this study, we introduced the Passenger Protection Wrap (PPW) with the object of solving the low risk deployment of passenger airbag. The conceptual design of PPW obtained the dispersion effect of the gas flow to both directions in the time range of 10-30 ms from the moment of impact at airbag. By applying the Taguchi method, which is a representative robust design method, PPW design parameters were optimized by a length of 850 mm, tear force produced by 6 and 4 cuts in the upper and lower wraps, respectively, sewing location of plus(+) 100 mm at center on basis of Z axis, and zigzag folding type. Out-of-position (OOP) tests were found to be less than or equal to the neck injury regulation limit of 80% , under the 3-year-old in positions 1 and 2, the 6-year-old in positions 1 and 2, and the 12-month infant in handle up and handle down positions conditions. These results were showed a good performance satisfying the FMVSS 208 requirements.
Also, this paper proposes a slim dual-type airbag system mounted on the instrument panel of a motor vehicle. The pressure of the airbag is concentrated on the sides of the passenger to prevent injury to the head, neck, or chest during the inflation of the airbag as a result of a head-on collision. The system was verified by the conduction of out-of-position (OOP) tests for 3-, 6-, and 1-year olds as suggested in FMVSS 208, as well as dynamic tests for males and females. The developed airbag system housing is 40-70 mm wide and the top- and middle-mounted airbags are respectively installed in the upper and front part of the vehicle instrument panel without interfering with the windshield or glove box. It was determined that a deployment angle of 60° and distance of 100-250 mm were required between the two airbags for their cushions to effectively protect the passenger by sliding into place rather than bouncing off each other.