Airbags-On & Off Switch?

There is an airbag deployment system where the pressure of the seatbelt actuates the airbag. This pressure, variable with the weight of occupant and impact severity, regulates the speed at which the airbag deploys. Additionally, this prevents deployment of a bag if there is no occupant. This http://www.wipo.int/pctdb/en/wo.jsp?wo=1998051545 is a link for a patent for such a system.

So, no pressure on seatbelt sensor, no airbag.

I don't know if any auto makers are using this system or not, but it would seem to answer your question.

"So, no pressure on seatbelt sensor, no airbag."

This would also be a flawed design. This would mean that if you don't wear a seat belt, the airbag wouldn't go off due to no pressure. As you are aware, many people don't wear seat belts. Government regulations protect occupents that do not wear seat belts, it's manditory.

This design would not be picked up by anyone if this is truly how it works. I didn't read through the patent though.

"Government regulations protect occupents that do not wear seat belts, it's manditory."

Source, please?

Which government? Original poster is from Argentina, are US standards enforced there? How about in India?

The issue of passenger restraint has become a real hot button in recent years. The link given by peterg7 in #3 gives quite a bit of information (generalized). One comment there is that the algorithms and logic control for airbag deployment are regarded as closely guarded secrets by manufacturers.

I agree, it seems counterintuative that the airbag does not deploy if no seat belt, but I didn't write the logic. There may be a reason, but it escapes me.

[EDIT] Re-reading the link, I find "...FMVSS 208 continues to require that bags be engineered and calibrated to be able to "save" the life of an unbelted 50th-percentile size and weight "male" crash test dummy."

This supports your statement, and answers the original question (if this rule is in effect in Argentina.)

"So, no pressure on seatbelt sensor, no airbag"

That comment is just wrong in so many ways.

As someone who began his 2nd career path (manufacturing) with TRW Technar who was at the time and probably still is under the TRW TED name when all these ideas were being born with the birth of the all electronic crash sensor and who years later worked for an OEM supplier developing the pressure sensor seat system for determining the mass/weight of a person in the car seat. That would be one of the dumbest management decisions someone could make.

That would be like introducing a product with no fail-safe mode. What if the sensing device within the seatbelt quit working? Do you seriously think that they would kill the car where it sits? That is what they would have to do in order to have your statement make in any sense at all.

I know in my experience with programmable pressure sensors we had the capability to detect when a sensor went into a saturated low (short) or saturated high (open) condition and we passed that information on to the customers specifically so that they could create fail safe modes to allow the vehicle to operate in a safe condition.

Having no airbag or no use of the car would not be part of that condition.

Anybody who has ever developed a PFMEA within the automotive industry would know that either one of those conditions would cause severity to be scored very high almost guaranteeing you to go back and correct or as I said earlier "making one of the dumbest management decisions someone could make"

As far as i am aware there is no sensor on the seat belts.

on impact the air bags deploy and on some models the seat belts automatically tension.

There is also as far as i know no variance of pressure on deployment.

if there were there would need to be some really complex weight sensing mechanism possibly in the seat

But i may be wrong.

http://en.wikipedia.org/wiki/Airbag

Good morning peter.

From your link:

"Advanced airbag technologies are being developed to tailor airbag deployment to the severity of the crash, the size and posture of the vehicle occupant, belt usage, and how close that person is to the actual airbag. Many of these systems use multi-stage inflators that deploy less forcefully in stages in moderate crashes than in very severe crashes. Occupant sensing devices let the airbag control unit know if someone is occupying a seat adjacent to an airbag, the mass/weight of the person, whether a seat belt or child restraint is being used, and whether the person is forward in the seat and close to the airbag. Based on this information and crash severity information, the airbag is deployed at either a high force level, a less forceful level, or not at all.

"Adaptive airbag systems may utilize multi-stage airbags to adjust the pressure within the airbag. The greater the pressure within the airbag, the more force the airbag will exert on the occupants as they come in contact with it. These adjustments allow the system to deploy the airbag with a moderate force for most collisions; reserving the maximum force airbag only for the severest of collisions. Additional sensors to determine the location, weight or relative size of the occupants may also be used. Information regarding the occupants and the severity of the crash are used by the airbag control unit, to determine whether airbags should be suppressed or deployed, and if so, at various output levels."

As i said at the bottom i may be wrong.

And i am very good at putting my foot in it.

But to be honest ive never heard of any in the uk, Although it is a good idea because there have been some nasty incidents with these airbags.

Of course the best way to avoid injury is to stop driving into things.

Take responsability for your actions and dont depend on design features to save you, Is my moto

As an engineer that designs airbags and safety parts for frontal crash, your point is not proven by what's said. It doesn't come down to the pressure in the seat belt, but the position of the seat relative to how close you are to the steering wheel, or dash on the passenger side, and the force, ie weight, of the person sitting on the seat. This is adjusted for different drivers/passengers. Of course there are other systems out there, but for the most part, this is the norm.

These things will alter the firing timing of the inflator. Most OEM's use a dual stage inflator. This is especially useful for little people that must sit close to the airbag.

The other fellow is correct, their is an initiator in the seat belt as well that's controlled by an electronic system.

It is just that, a system. It's suppose to work together with the seat belt, knee bolsters, steering wheel, etc., to absorb the energy over time during collision. Of course FMVSS208 also specifies that you must test without the seat belt as well, making the other components very important for absorbing energy.

Of course it's best to use the seat belt that way you're protected by the entire system. As you can guess, injury value does increase when you don't wear a seat belt.

In my wife's Saturn Aura, there is a light to indicate whether the Passenger seat belt is activated or not. I don't sit still! When she is driving, the light commonly goes on and off according to my position. If I lift my legs and skootch (how do you spell that?) back to increase the pressure on the seat, I can always make the light come on. I keep forgetting to ask the service people whether the sensor is misplaced, badly adjusted, or???

I always use the seat belt. It has a sensor in the latch to know whether the seat belt tip is inserted, but it clearly does not depend on tension, only on being latched.

Many vehicles with no back seat have key switches that allow you to turn off the airbags even when pressure is on the seat for the passenger. This makes it possible when an infant car seat has no other place to be positioned. My wifes car senses what seats are occupied and whether the belt is connected.

Aussie, congratulations.

This is the best air bag.

Best regards,

Arturo

WHERE CAN I GET ONE ALIKE!!!!!!!

Things have changed, many years ago it was said that anyone in an airbag car, that did not have his seatbelt on, would probably get a broken neck from the airbag if it deployed, or a broken head and neck if it didn't deploy - assuming a reasonable road speed of course of 30MPH or more........

Obviously that is not true anymore if the above posts are to be believed.....