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05-23-2002, 00:10

Today in science we had a debate how airbags work and how long they stay open for. Our sciece book said that airbags are activated when sensors detect the the car rapidly slow down, but that would mean that when ever you slam on your brakes, the airbags would go off. I thought they had sensors in the front of the car that would detect a collision and that would activate them. Also during the class, I had another arguement with the resident 'Holden Man' who said that airbags stay open for about a minute before they go down.
Can someone please varify what I said.

SM · 05-23-2002, 00:15

mmmmm, science teacher must have a part time hobby in the lab. And I just thought that big pillow popped up when the brakes went on in case I wanted a sleep.

Martin · 05-23-2002, 00:25

They only stay inflated for 0.5sec if that, if he doesnt believe you show him a video of crash test. He has been watching too many movies I think.

And yeah there are sensors in the front that set off the airbag when it detects a hard/fast enough impact. Got nothing to do with the brakes.

3Toed · 05-23-2002, 00:26

Indeed. Ask the teacher what would happen if you're parked and someone ploughs into your front. No slowing down there but you'd want to airbag to activate anyway, unless you want to be known as "steering-wheel-face(tm)".

I saw a show about car safety on Discovery Channel a while ago and they showed an airbag deloyment in slo-mo and it collapsed as soon as it had inflated. The purpose of it is to stop your face flying forward - not to pin you up against the seat.

Having said all that, I hope I never see my airbag.

Damegravey · 05-23-2002, 00:29

What is it with science teachers that think they know everything about everything?

Airbags are deployed when sensors fitted to the vehicle detect a specific level of G forces generated by extreme deceleration. like when it is hitting something pretty hard, not at the low levels of G forces experienced in hard braking. Different vehicles have the sensors set at different levels.

I don't know the time the bags stay inflated for, but if you blink you'll miss seeing them. Who wouldn't blink with a high speed brick wall coming towards you.

If you wish PM me and I'll try and find some info we put out on airbags some yars ago!

05-23-2002, 00:30

Thanks guys

About the science teacher, she wouldnt have a clue.

Fireman Sam · 05-23-2002, 02:14

An airbag system consists of the airbag module which contains an inflator, the airbag itself, and a trim cover. The proper firing of the airbag is controlled by crash sensors which supply electrical signals to a control unit which fires the inflator to inflate the airbag.

The driver-side airbag module is in the hub of the steering wheel. The passenger-side airbag module (if so equipped) is in the dashboard above the glovebox.

Ths is what happens when an airbag deploys in a crash:

In the 15 to 20 milliseconds after impact, the crash sensors and control unit determine the severity of the collision and decide whether to deploy the airbag.
At about 25 milliseconds, the airbag splits its covering pad in predetermined places and begins to inflate rapidly.
At about 45 milliseconds, the bag is fully inflated while the seatbelted occupant is still moving forward.
At around 60 milliseconds, the occupant contact the airbag which immediately begins to deflate via vent holes in the back.
Up to 100 milliseconds, the occupant continues to sink deeply into the airbag which cushions the head and chest while it is deflating.

http://www.dotrs.gov.au/land/vehicle...ADR/airbag.htm

RAPTOR · 05-23-2002, 16:19

I bit more info.

I was informed by my Highway Patrol "bro-in-law" that the latest airbags will not deploy below a set speed (can't remember what that was). Apart from the "steering wheel" face effect this is also to prevent crims from reversing into pursuing police vehicles at speed in an attempt to conclude the pursuit by deploying the police airbag.

Pearly · 05-23-2002, 16:28

I think it's 40 kph that the car can hit something and the airbag will not deploy. I read it somewhere...
*car manual me thinks*

IPhido · 05-23-2002, 16:35

They use G-sensors to deploy in a accident. Typically I think they are set to something like a decelleration of 25 G. Thats quiet a impact, so gunning the car hard in reverse, or hard cornering, or small impacts and rough roads won't set them off.

Airbags can cause injury in low speed collisions, if the occupant is a small child or inncorrectly seated. Small finger injuries are possible because the air bag is accually classed as a explosive charge userally and is very forceful having a short time to inflate the bag and once "detonated" the bag begins to deflate to help absorb the impact. When a airbag goes off, often the drive has there hands firmly holding the wheel to brace for impact so this is not a suprise.

Air bags are designed to be used in conjunction with seatbelts. There are a varitiy of diffrent systems, which deployment speeds may vary.. I know german ones are designed to be quiet fast as germany the chances of a high speed collision are accually quiet high. American ones may be quiet slow as any injury due to deployment could cause legal implications.