On 06.10.1951 it was Walter Lindner from Germany who applied for a patent for his invention. It was an inflatable container that inflates automatically in the event of danger. However, Lindner, who was from Munich, Germany, titled his invention as a device to protect against occupants in vehicles during collisions. The similarity of the descriptions still resemble the later airbags; nevertheless, at that time the implementation from idea to practice proved to be rather complicated. There are still certain deficits, such as:
- in the required tear resistance of the envelope,
- the sensor system for triggering, and
- pressure generation to fill the airbag at lightning speed.
Today’s Mercedes-Benz AG has been working on the airbag since 1966. In 1980, the first S-Class sedan with a combined system of belt tensioner and driver airbag was revealed. The public world premiere of this system then took place at the IAMS (Amsterdam International Motor Show) in February 1981. Mercedes did not invent the airbag, but they laid the foundation for today’s airbags, which are suitable for series production.
First model with airbag appeared in the USA
Due to the high number of fatalities in the USA in the early 1970s, this led to a demand for more occupant protection in cars. General Motors provided the first answer: the „Air Cushion Restraint System“, or ACRS for short. GM offered this variant from the 1974 model year in some brands such as Buick and Cadillac. Naturally, this was only available for a surcharge.
The main aim was to do away with the so-called three-point seat belt, which drivers often found very uncomfortable and inconvenient. At that time, the system only included a knee pad and a lap belt. This is the decisive difference to Daimler’s principle, which is still valid today. The airbag is a supplement to the three-point seat belt.
After only two years, the production car with the first airbag disappeared again from the General Motors program. This was not least due to the very costly and time-consuming maintenance. Many owners of such cars later even had the system deactivated and three-point seat belts installed. Moreover, it was not economically viable for General Motors anyway, since there are no known high order numbers for these models.
The airbag must not burst
Despite all this, there were still some problems, such as the extremely fast inflation of an airbag, which should happen within 30 milliseconds. The breakthrough of fast gas generation then ultimately came from the system of rocket engines using a solid propellant. The airbag’s propellant was thus based on a mixture of sodium azide. Bayer-Chemie then developed an airbag gas generator. This produced pure nitrogen after ignition and was thus harmless to the occupant.
The aim was to allow the airbag to open in such a way that it would not burst in the event of a collision. The solution was polyamide, which today was much thinner and lighter than 40 years ago. In addition, the airbag also had to be stowed safely in a turning steering wheel without affecting the functionality of the airbag. Sensors were there to distinguish whether the impact was from 20 km/h or more or just a light parking bump. Bosch was also involved in the development, and the world’s first electronic airbag control system went into series production. It took a good 15 years from the start of research until the optimum solution was found.