Airbags, great and mysterious, hiding in the places we can’t see while offering us the greatest help when needed. And in one car, there are several of them, according to the positions, there are driver and passenger airbags, side airbags, side curtain airbags, knee airbags, there are even seatbelt airbags, pedestrian airbags, and roof airbags.
Among these airbags, due to various reasons, pedestrian airbags and roof airbags have extremely low configuration rates. For example, there’s only Citroen C4 Cactus that’s equipped with roof airbags.
But the weird thing is that the pedestrian airbags (Volvo V40, Subaru Legacy Outback) which also have a very low configuration rate are having an extremely high exposure and are highly praised by the people.
How come the importance of roof airbags has never been noticed by the public? Is it possible for it to evolve in the future?
Are roof airbags useful? Why does it have such a low exposure？
The roof airbag is designed to prevent passengers getting injured from hitting the roof. It is most useful in two scenarios:
When the rear passenger is not wearing a seatbelt and gets ejected from the seat, hit the roof of the car.
When the car rolls over in a car accident. In this case,the front and rear passengers are both likely to hit the roof.
In fact, in terms of its protection ability, the roof airbag is absolutely excellent and useful, it can well protect the fragile parts of passengers’ head and neck, and avoid serious concussions and neck fractures. And for cars with panoramic sunroof, it can also effectively avoid the danger of passengers being thrown out of the roof during car accidents. According to a survey from the IIHS (Insurance Institute of Highway Safety), from 2000 to 2015, of the 13,700 serious traffic accidents that occurred in the United States, 17% of them the passengers were thrown out of the car through the sunroof. And if there are roof airbags, this hazard will surely be greatly reduced.
The stimulation photo below vividly shows the role of the roof airbag.It is easy to notice that the passenger on the left car is flying out directly from the sunroof, which is very dangerous.
There are probably two reasons why the roof airbags are not widely used or even don’t have a high exposure despite it’s protection ability.
1. The high cost
The investment in the roof airbags are quite high at the beginning, and the airbags can’t be reused after being triggered, causing extra high expense when replacing as well.
The exposure of the pedestrian airbag would not get so much exposure as well if it’s not equipped by Volvo who is famous for its safety.
2. Hard installation and limited space
Take the example of the roof airbag developed by Hyundai Mobis (subsidiary of hyundai kia motors) and INALFA (professional manufacturer of sunroof), this airbag is designed in the rear section of the roof, and its extension is guided by a wire rope arranged around the sunroof.
This structure is much more complicated than any other airbags. Even for the side curtain airbags, wire rope guidance is not needed.
Side curtain airbags are the largest airbags that are widely used in automobiles, but its structure doesn’t occupy a lot of space, and doesn't need a guiding mechanism, which reduces the cost and has high working reliability.
3. Low motivation without regulations and promotions from safety inspection agencies
In fact, most of the widely used safety components have a lot to do with the promotion of regulations and safety inspection agencies. For example, side airbags and side curtain airbags also had low equipment rate until the IIHS included side collisions in the assessment.
When only one of the first five models to participate in the test was rated "A", and the rest were all "P". For example, the picture below shows the test situation of Toyota Corolla (2003 model). The driver’s head hit the window glass directly (the side curtain airbags can prevent this damage), and the driver’s pelvic bone was also seriously hurt (the side airbag can protect this from happening).
In a word, the last time the roof airbag tried to promote itself was through it’s safety enhancement. But it didn’t attract much attention, and with the improvement of various active and passive safety technologies, people are paying even lower attention to it.
Does that mean the roof airbag will eventually disappear? Now it seems that it’s going to get a new chance to grab people’s attention! And the new chance is automatic driving!
Most people might think automatic driving and airbags seem to be two very different things, but there is a connection that people tend to ignore, the steering wheel.
The steering wheel is where the drivers airbags are put, and the goal of automatic driving is to eliminate the steering wheels.
Take what Audi showed us with its skysphere concept car for example. In the Grand Touring mode, the steering wheel and pedals will be stretched back, and the car will complete the driving task by itself.
In a word, we can see from those concept automatic cars that cars without a steering wheel, or a hidden steering wheel is the future, the driver's airbag needs to find another place to hide.
Actually in the early years, a new design idea of installing the airbag on the ceiling above the windshield appeared, which can be deployed along the windshield to provide protection for the driver when a frontal collision occurs.
We can see its working theory from the photo below. The roof airbag uses a tubular hybrid gas generator similar to the one used in the side air curtain. The advantage is that it does not occupy a lot of space and is very suitable for hiding in the ceiling. In addition, the inflating capacity of this gas generator can be bigger, which can ensure the smooth open-up of this new type of airbags.
However, the size of this airbag is also larger than the drivers airbags that hide in the steering wheel, which also means the cost is higher. What’s more, the ceilings of cars are usually one integrated piece, and after the airbag is triggered, it will unfold along the weakening line of the airbag cover, and ruin the entire ceiling. So we will also need the technique to find a solution to the need of replacing the entire ceiling once the airbag is triggered.
Of course, with the rapid development of auto driving , I believe these design details will all be solved in the near future, and the roof airbag will definitely be the first choice to use for eliminating the steering wheel.
What is a roof airbag? As the name suggests, it is an airbag installed in the roof. And at this moment, we are already seeing two variations: 1. The airbag prevents the juries by hitting the roof. 2. The airbag to replace the drivers airbag which is now installed in the steering wheel.
Automobile manufacturers all tend to promote their cars with full-on protection, but if we look closely we will notice that there are lots of weak spots actually and the roof has always been one of them. There are almost no protections on the roof or ceiling, due to the high cost, complex structures and also lack of regulation to promote it from the big picture
As for the second type of roof airbag that we mentioned earlier, I believe it will be more familiar to people very soon with the development of auto driving!.
