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Old 27th February 2015, 20:23   #16
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Default Re: Airbags: All you need to know!

First i would like to say that you have sure worked a lot to put such a detailed thread .But i would like to point a tiny error in the information you gave about. True they are like cushions and can be used as one too. They do provide cushioning but this is how they work. The work of the vents is not so that the visibility of the driver is not compromised . Ill tell what is their role. I am not talking about deployment as you have already explained about that amazingly. So here is it after deployment when a person hits the bag after a crash the vents act as pathways through which in this case the nitrogen can escape because if the nitrogen doesn't escape then due to the enormous energies absorbed the bag will explode which will injure the passenger more .
source :the personal airbag episode from prototype this tv show from discovery
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Old 27th February 2015, 20:30   #17
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Fantastic thread sir. Just by reading the title of this thread I recalled an incident which happened in the year 2005. We were in the Hyundai showroom to take delivery of our Santro Xing and along with us there was a family taking delivery of a Hyundai Tucson.

The salespersons were explaining the functions of the Tucson to the new owner and while discussing airbags, the owner promptly said, "Airbag nikal jaega to wapas hawa bharane ke liye alag paisa dena padega, aisa airbag ka kya faida" (Translation: What is the use of an Airbag if one needs to "refill" air by paying money in case the airbag deflates).

Apart from this, all of us must have heard stories where people ask salespersons to show if the airbags are working or not by deploying them.

But I believe a decade later since that incident, a lot of people have become aware of such safety features. With lot of initiatives taken by individuals to spread awareness amongst the community and the Government taking steps to make safety features mandatory, in a few years the market will soon become mature and aware of the benefits of airbags.
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Old 27th February 2015, 21:54   #18
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Default Re: Airbags: All you need to know!

Excellent topic Saket. Thanks for sharing and you have written it in a very easy way so every one including non technical persons can understand it very well.

Quote:
Originally Posted by saket77 View Post
Also, the SRS depends on the feed from the sensors to sense a crash. The sensors are placed at strategic locations in the car, mostly near the front bumpers so that they are most likely to be hit in case of a crash and hence send a signal to the control unit to trigger the deployment. But in a real world scenario, accidents like under-running a higher vehicle like a truck (without under-run protection) will not impact the front bumpers (and hence the sensor), but the crash may still be fatal. In such cases, the chances of airbags deployment can be low.
Am quoting SS-Traveller from another thread for the below Fortuner accident. As you mentioned above the sensors are generally placed behind the bumpers. From the look it seems the Fortuner has rear end some high trailor .
Quote:
Originally Posted by SS-Traveller View Post
airbags haven't deployed. Found it parked at our local police station this morning. No idea of when and where this happened.
Airbags: All you need to know!-dsc_0811.jpg

Airbags: All you need to know!-dsc_0812.jpg

In another example i found airbags has not deployed in this Etios crash.
This was put down by Amalji, as what Toyota showroom told him.

Quote:
Originally Posted by amalji View Post
Talked with service team lead of Nippon Toyota, Kalamassery. These are his inputs.
  • The passenger was not wearing seatbelt and banged his head on the glass. The driver was wearing a seatbelt and hence he was unhurt (inspite of sitting closer to the steering)
  • This was not an accident which needed an airbag to save the passenger. Airbag expanding algorithm is carefully designed only to come out when really needed.
  • One important factor that triggers the airbags is the amount of deceleration. By just hitting against something head on doesn't necessarily trigger the airbags. In this particular case, it was not that high and hence airbags were not needed.
  • Airbags without the use of seatbelt is useless.
Airbags: All you need to know!-10750191_10204710520095324_8960821126435232779_o.jpg

In both the cases it looks like the airbag sensors were not triggered properly.

Now my question is accidents can happen from any angle. I remember a case where an i20 hit a pole (Lamp post) and airbags were not deployed due to the very same reason. Same should occur in case of a side ways crash where the front bumper is not involved. So my basic query is why the manufacturers do not increase the number of sensors and put them in few more locations like the A pillar or some place which is higher than the front bumper ? Am just asking because of the pure lack of my knowledge. Is this because it will increase the car cost or there are any other reasons?

Last edited by Samba : 27th February 2015 at 21:56.
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Old 28th February 2015, 00:41   #19
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Great writeup Sanket.
1 point I would like to add is as and when the bags deploy and deflate, get out of the vehicle as soon as possible/safe to do so. The airbag can save you once, from a head on collision for example, but it is useless if a second vehicle rams into your vehicle.

Last edited by GTO : 28th February 2015 at 14:55. Reason: Typo
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Old 28th February 2015, 01:26   #20
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First of all, a very well written price on airbags Saket. I am sure most bhpians would know something or other on airbags already but the way you have detailed it out, I am sure even experts will find something new to learn from this thread.



Quote:
Originally Posted by Samba View Post
In another example i found airbags has not deployed in this Etios crash.

I remember a case where an i20 hit a pole (Lamp post) and airbags were not deployed due to the very same reason. Am just asking because of the pure lack of my knowledge. Is this because it will increase the car cost or there are any other reasons?
I also have similar question actually. I am assuming that the sensors are placed at some locations behind bumpers and other crash sensitive parts of the car. My query is on the trigger mechanism of these sensors.

Are they triggered only when they sense direct impact at locations covered by them or are they also triggered on rapid deceleration ( as what happens in accidents)

If it is latter, the case mentioned by Samba is interesting as even if the i20 crashed into a pole missing the sensor trigger points, the deceleration should have triggered the airbags.

In the same light, is there also a difference in trigger mechanism in different classes of vehicles? For example, would a BMW have more number of sensors/ better sensing mechanism/ deceleration detection for airbag trigger than a more run of the mill hatch? Also talking about just front airbags, would the quality of protection offered by one in BMW would be different from one in Maruti (ignoring the car structure and build)
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Old 28th February 2015, 04:16   #21
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Quote:
Originally Posted by Samba View Post
...
Now my question is accidents can happen from any angle. I remember a case where an i20 hit a pole (Lamp post) and airbags were not deployed due to the very same reason. Same should occur in case of a side ways crash where the front bumper is not involved. So my basic query is why the manufacturers do not increase the number of sensors and put them in few more locations like the A pillar or some place which is higher than the front bumper ? Am just asking because of the pure lack of my knowledge. Is this because it will increase the car cost or there are any other reasons?
The question is genuine. It all depends on the manufacturer where he places the sensors and how many they provide. Each assembly of airbags involves some serious engineering with estimation of motion of occupant in car during collision.

Now sensors could be mounted to A pillars and doors for detecting frontal-side or side collisions. During side collision, on rough estimation, the occupants would bang on to their side opposite to the direction of impact (inertia stuff). But if manufactures decide to omit curtain airbags (side) with sole reason of reducing costs, there won't be any use of deploying front airbags in most of the side collisions. Why omit such a safe feature ? Simply because side collisions are much less likely to happen than frontal collision.

Regarding vertical height of positioning of sensors, one might think what would be the need of height sensors since bumpers would be the first one to crash! Lets bring truck into the accident. What if one crashes into a truck from side or rear ? Yes, it would be a direct hit to A pillars for most of the cars, without touching bumper. So here comes the need of positioning sensors at height too!

But Indian Road Ministry had made it compulsory for all vehicles with lowest part of chassis having greater height than "X", should have steel bars installed below so that it reaches a height of "X" at least. I don't remember if it is also for sides of trucks but in US there is such rule for all directions.

So ideally there would be very rare cases in which frontal crash is caused with bumpers remaining undamaged. And IMO, this is the reason most (all maybe?) omit the heights more than height of bumper for locating sensors, useless costs. At sides of a vehicle there can be different scenario since all impacts from sides would impact almost at the same time at different heights.

Quote:
Originally Posted by vivekz View Post
...
I also have similar question actually. I am assuming that the sensors are placed at some locations behind bumpers and other crash sensitive parts of the car. My query is on the trigger mechanism of these sensors.

Are they triggered only when they sense direct impact at locations covered by them or are they also triggered on rapid deceleration ( as what happens in accidents)

If it is latter, the case mentioned by Samba is interesting as even if the i20 crashed into a pole missing the sensor trigger points, the deceleration should have triggered the airbags.
IMO, the logic takes both, direct impact as well as deceleration, having some different weightage to both . Do think of side collision where deceleration would not be much of value. Also frontal collision while stationary (head-on). So there is surely more stuff in the logic.

Anyone want to throw some light on it ?

There could be a number of reasons for undeployment of Airbags within my domain of knowledge.

1. Malfunction could not be ruled out
2. Sensor in region of hit, failed, or was not present at all and/or
3. Deceleration might not be the only factor besides the contact by sensors.

Quote:
Originally Posted by vivekz View Post
In the same light, is there also a difference in trigger mechanism in different classes of vehicles? For example, would a BMW have more number of sensors/ better sensing mechanism/ deceleration detection for airbag trigger than a more run of the mill hatch? Also talking about just front airbags, would the quality of protection offered by one in BMW would be different from one in Maruti (ignoring the car structure and build)
Everyone must be aware, or now be aware, of Takata Airbags global recall. It has affected 100% of the big manufacturers globally. I think this might mean there is no/very little difference in "Airbags"

Now, regarding mechanisms, IMO, the basic mechanism is common. But there would be a major difference in the logic, sensor position, airbags position, timings, etc.

By comparing a Maruti with BMW I would prefer to say BMW might have better research and engineering in designing of SRS than Maruti but can't compare when we consider "Suzuki"
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Old 28th February 2015, 08:35   #22
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Quote:
Originally Posted by saket77 View Post
9. Kids & short adults stand a greater risk of sustaining airbag injuries in case of deployment. Hence, it is better for the safety of kids to secure them with the seat belts in the rear seats. Very young kids and infants should be always secured in a child seat at the rear.
Dear Saket77, Thank you for a most informative and useful post that I hope every BHPian reads. Your article is very well written and to the point. Certainly I learnt a lot. One observation in our country is that adults often sit in the front passenger seat with a child in their lap. The adult may or may not be wearing a seat belt but the child sadly is not restrained. This results in the child taking the impact of a collision. Sharing with all BHPIans - in 1998 one of my employees was travelling in his M800 with wife in the passenger seat and two year old son in the wife's lap. Somewhere on the Delhi- Meerut road they had a head-on collision. Both adults got injured (no seat belts) but what was tragic was that the 2 year old took the brunt of the impact that saved his mother. The impact killed the child. I cannot express in words the trauma of that poor lady. Just sharing as this is a common practice in our country. Regards - Narayan
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Old 28th February 2015, 14:05   #23
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Quote:
Originally Posted by saket77 View Post
...there are several reports ... of airbags not deploying in case of crashes.
...sometimes the SRS do not deploy because the crash & the conditions did not 'fulfil' the logic rules of the algorithms designed for deployment and at times the airbags may not deploy when genuinely they are not needed. At times, it can be a case of plain and simple failure of SRS.

In my opinion, the system is still developing and will keep on improving in accuracy as manufacturers include and design more complex algorithms to mimic the varied real world scenarios. But still at this point of time they are a huge success and are bringing down mortality rates. The chances of airbags not deploying is small even in today's world.
To add to your reply, I thought I would highlight on this thread what I had written earlier...
Quote:
Originally Posted by SS-Traveller View Post
Airbags are triggered by impact sensors near the front corners, usually located behind the bumper frame and about 8" off the ground.

The collision force has to be
  • severe enough,
  • involving either or both sides and
  • low enough to deform the chassis section where the sensors are located
for airbags to deploy.

A look at the Honda City's airbag sensors. Going under a truck or hitting a pole with the middle of the bumper causes no effect on these sensors - and therefore no airbag deployment.


Please understand that airbags don't deploy every time there is an impact on the front of the car. How the sensors are located matters. In the pic above, the sensors are located behind the bumper frame - so the frame has to substantially deform for the sensors to trigger. Mild fender benders won't trigger airbags, even at 20 kmph.
Quote:
Originally Posted by SS-Traveller View Post
Analysing the pictures from another thread (Toyota Etios airbags not deployed on accident), let's see where approximately the airbag sensors are located (red circles), and where the bulk of the impact happened (green boxes) (photographs downloaded from FB and suitably edited).






We can't expect airbags to deploy in this situation, nor is it the car or manufacturer's fault. If a service centre guy said, “It’s because you did not collide properly”, there's possibly a modicum of truth in it!

Maybe manufacturers need to relocate their airbag sensors for airbags to deploy more easily - but then there would be so many airbag deployments in mild shunts, that we'll need another section, not a thread, to report all those cases!
Quote:
Originally Posted by SS-Traveller View Post
Most common (low end) cars sold in India do not have accelerometers and gyroscopes and deceleration sensors etc. The sensors are usually of the electro-mechanical crush-dependent type, only working when physically broken / affected. Accelerometer-based sensors are obviously more expensive, and also more easily triggered in minor fender benders. And of course, a single accelerometer type sensor installed inside the cabin or engine compartment is good enough to sense the rapid deceleration caused by frontal impact, so why do we need two of those things on the two front corners, just behind the bumper frame?

Disclaimer: I have not physically opened up and checked & researched types of airbag sensors used in different cars in this country, so while reading some of my generalized statements, please do not draw any conclusions that the same may be applicable to your own car. Check and confirm with your manufacturer.
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Old 28th February 2015, 18:09   #24
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Airbag burns can be quite serious. Please forgive the gruesome pic below, and apologies if I have hurt any sensibilities. But any doubt you had about a soft, feathery cushion coming up to meet your face like an angel should be dropped with immediate effect.
Which is why the repeated warning from the posters in this thread to WEAR THE SEATBELT!
Here's a common picture on the net.

Name:  096_ro0213_tr1.gif
Views: 1109
Size:  49.9 KB

And here's a link to a med site explanation.
http://www.medscape.com/viewarticle/490128_4
High alkaline content in the chemcial mix reacts to sweat and other fluids coming out of pores. ON a lighter note, at least try not to cry and drive :-) but with Indian roads being what they are every driver cries silently for his shocks. :-)

Last edited by Rehaan : 3rd March 2015 at 17:56. Reason: Please use our attachment system, rather than hot-linknig pictures (which is not allowed). Thanks.
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Old 28th February 2015, 18:25   #25
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Default Re: Airbags: All you need to know!

Dear Taffy,

It is true that airbags can cause serious injuries and specially to those who are not restraint by seat belts. But if there were no airbags, the person (in the picture) may not have lived at all. I do not intend to offend you but I feel the use of this gruesome picture may fuel more senseless & strange arguments by people to avoid a car with airbags. And I am sure, that was not your intention as well.

Thanks for your understanding.
Regards,
Saket
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Old 28th February 2015, 23:45   #26
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Quote:
Originally Posted by saket77 View Post
...I feel the use of this gruesome picture may fuel more senseless & strange arguments by people to avoid a car with airbags.
I wouldn't think so.

The utility and value of airbags in preventing grievous injury and saving lives has been scientifically proven many years ago. Anyone arguing against having airbags deserves to receive infraction penalties and have such posts deleted from this forum.
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Old 1st March 2015, 01:16   #27
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What a fantastic, informative read! Thanks for sharing.

On similar lines, while a lot of people have ABS in their cars, most of them don't know exactly when ABS kicks in and how to optimize and use the ABS to good effect when a dreaded panic situation arrives.

It took an extremely good salesman in Honda to demonstrate the power of ABS to me during a Test Drive. I'm glad he didn't demonstrate the use of airbags. :P
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Old 1st March 2015, 02:42   #28
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Default Re: Airbags: All you need to know!

This is a great thread, and deserves to become a reference.

Quote:
Originally Posted by Ashir View Post
1. Is it normal that airbags deploy even when minor collisions at stop/go traffic or at speeds of 40-50kmph ? (Rear ending someone)
I have no idea how the manufacturers would define minor. 40/50kph is quite fast, in terms of our bodies hitting something. If you walk into a wall, or, worse, a tree branch or pole at head/face hight, you will probably cry, at least silently. You speed may have been 4 or 5kph, one tenth of the speed that many people frequently attain and call "city speeds."

Quote:
Originally Posted by V.Narayan View Post
... ... Sharing with all BHPIans - in 1998 one of my employees was travelling in his M800 with wife in the passenger seat and two year old son in the wife's lap. Somewhere on the Delhi- Meerut road they had a head-on collision. Both adults got injured (no seat belts) but what was tragic was that the 2 year old took the brunt of the impact that saved his mother. The impact killed the child. I cannot express in words the trauma of that poor lady. Just sharing as this is a common practice in our country.
I wish you would share this more widely. Many people will have no interest in air bags, and some of us, like me, even with interest, might miss it.

It is vital that people start to learn the consequences to unrestrained children in the case of such accidents. Let the child not die in vain, but save the lives of others by example.

It can also not be said too many times how dangerous the airbag is to a child in this situation.

Quote:
Originally Posted by saket77 View Post
Dear Taffy,

It is true that airbags can cause serious injuries and specially to those who are not restraint by seat belts. But if there were no airbags, the person (in the picture) may not have lived at all. I do not intend to offend you but I feel the use of this gruesome picture may fuel more senseless & strange arguments by people to avoid a car with airbags...
Saket, I feel the post and picture is important, underlining the fact that seat belts and air bags work together.

There will always be those who argue. I used to scream and shout when the doc gave me life-saving inoculations as a child. I was an uninformed child, and all I knew was that it hurt. The world is full of uninformed children of all ages.

OK, so I've been wearing seat belts religiously for decades anyway, but I never thought about what an airbag could do to my face until a friend told me his experience, just a year or two ago. The point is, blood and bruises we can live with: broken skulls may not give us that chance.
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Old 1st March 2015, 08:58   #29
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Quote:
Originally Posted by Thad E Ginathom View Post
This is a great thread, and deserves to become a reference....

I wish you would share this more widely. Many people will have no interest in air bags, and some of us, like me, even with interest, might miss it.

It is vital that people start to learn the consequences to unrestrained children in the case of such accidents. Let the child not die in vain, but save the lives of others by example.
Dear Thad, well said. I am relatively new to Team BHP. If you could give me some direction on the threads or sites to post this on I will be pleased to do so. With kind regards - Narayan
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Old 2nd March 2015, 09:29   #30
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Fantastic thread! Thanks for the information!!

Does the car / engine become immobilized, after the airbags are deployed? OR if the impact is minimal in nature (only shell damage), but good enough to deploy airbags, can the car be driven to the nearest safe place / service center?

Thanks in advance!!
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