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Old 9th March 2015, 01:27   #46
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Default Re: Airbags: All you need to know!

Thanks for the informative post Saket ! Hopefully it will put to rest the doubt in people's heads about the effectiveness of airbags and the fact that they are NOT fluffy pillow


Would like to add some input on the less common airbags-


1) Torso Protection Side Airbags:

These are rare in India and often present along with curtain airbags (more on that later) with the sole exceptions being Chevrolet Cruze and Nissan Micra which offer them without curtain airbags.

In a front-end collision the engine compartment is designed to collapse and absorb the impact. A car that is hit on the side has only the door and a few inches of space to protect the occupant. Drivers and front seat passengers were left vulnerable to side impacts. Rather than thicken doors to the point where they would become too heavy to be operable (case in point being Obama's limousine's door which requires two men just to open and close. Ofcourse those doors are thick for a different reason but you get the point) automakers added additional airbags where they would be most beneficial. Side collisions are most dangerous to a vehicle's occupants because the crumple zone is so small, so airbags were added to doors and front seats to protect the chest and thorax area of front passengers.

While most cars in India have the these Chest Side Air Bags (SABs) mounted on the seats




,in some countries they are mounted on the car's doors.




Also since these provide a high degree of intrusion into the occupant's space children below a certain age are prohibited from sitting in front seats in most countries with strict roads laws as their fragile torsos can be harmed by these airbags.

2) Head Protection Side Airbags (or curtain airbags):

Since side curtains often cover most, if not all, of the window space, they can provide a barrier that helps prevent ejection from the vehicl Even when seatbelts are used properly, a crash might force arms head through the windows and cause serious injury there. The side curtains' internal structure is strong enough to minimize the risk of full or partial ejection. They are also able to keep out intrusions such as metal, broken glass, and other crash debris, cutting down on injuries such as broken bones, cuts and bruises.

They also remain inflated for a slightly longer time period than the other airbags since they are also meant to protect from roll overs which can last longer than the average crash.




3) Knee air bag:

These are the rarest of all airbags in India. Only high end luxury cars have these.

Knee airbags are located below the steering column on the driver's side. If present on passenger side then it is usually mounted below the glove box.The knee airbag not only reduces leg injuries but also provides benefits for the head and chest by keeping the occupant in the proper position to receive maximum protection afforded by the regular front airbag.




4) Rear Curtain shield airbag:

I doubt this is available in any car in India at all.

As the name suggests these airbags protect the rear passengers from rear impacts. Since the headrests do the job of preventing whiplash i guess these airbags, much like the curtain airbags do in case of side impacts, provide a barrier and prevents crash debris from entering the cabin and injuring the occupants.




5) Pedestrian Airbag

Again I doubt if this is available in any car sold in India.

These are obviously for the sake of protecting pedestrians in the case of an accident. Since the knees of the person strike the bumper and the torso,head strike the bonnent these are the areas that are built to crumple easily as well.The placement of airbags though can vary from manufacturer to manufacturer.

The image below is of a Toyota car showing all the above mentioned airbags (notice the placement of pedestrian airbags)
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Old 9th March 2015, 03:43   #47
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Default Re: Airbags: All you need to know!

Amazing. I had no idea about most of those airbags!

On a black-humour note: the day pedestrian airbags are available on a car in India, it's buyer will fit bull bars
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Old 9th March 2015, 07:37   #48
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Default Re: Airbags: All you need to know!

Quote:
Originally Posted by Rollingwheels26 View Post
5) Pedestrian Airbag
Again I doubt if this is available in any car sold in India.

These are obviously for the sake of protecting pedestrians in the case of an accident. Since the knees of the person strike the bumper and the torso,head strike the bonnent these are the areas that are built to crumple easily as well.The placement of airbags though can vary from manufacturer to manufacturer.

The image below is of a Toyota car showing all the above mentioned airbags (notice the placement of pedestrian airbags)
Are these designed to protect pedestrians after hitting them?. Not sure if the force generated by a pedestrian will be sufficient to set of the airbag without being too sensitive.

Last edited by knaveen : 9th March 2015 at 07:41.
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Old 9th March 2015, 09:25   #49
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Default Re: Airbags: All you need to know!

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Originally Posted by knaveen View Post
Are these designed to protect pedestrians after hitting them?. Not sure if the force generated by a pedestrian will be sufficient to set of the airbag without being too sensitive.
These airbags inflate only when the vehicle speed is between 20-50 kmph (since beyond these speeds airbags are pretty much useless). Also when you strike a human body (soft) the compression of bumper is obviously lesser than what would have been had you hit a harder object like a car or a wall. Hence the sensors inflate the pedestrian airbag appropriately.

But you have to marvel at the tech that goes into building sensors that vam differentiate between the two types of crash in milliseconds. This is obviously harder to build than your normal driver/passenger airbags.

A disadvantage is that, I feel, these airbags will inflate when you hit a stray animal as well (high possibility on our roads )



Quote:
Originally Posted by Thad E Ginathom View Post
Amazing. I had no idea about most of those airbags!

On a black-humour note: the day pedestrian airbags are available on a car in India, it's buyer will fit bull bars

Well the day these airbags are available on our roads will be the day when we have strict road rules that are implemented as well (including no bull bars). I know it seems far fetched but a petrol head can dream right ?

Last edited by Rollingwheels26 : 9th March 2015 at 09:29. Reason: added comment for thad e's comment
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Old 9th March 2015, 09:36   #50
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Default Re: Airbags: All you need to know!

Quote:
Originally Posted by Rollingwheels26 View Post
...the less common airbags-...
Thanks for highlighting the other types of airbags not usually seen in vehicles in India.

One more airbag to be added to the list is the anti-submarining airbag. More details about it on this link: http://www.renault.co.uk/safety/inno...otect/airbags/.

Quote:
Collision protection which is equally effective for both 3-door and 5-door cars.

Situation
On coupés and coupé convertibles, it is not always possible to fit multiple seatbelt pretensioners, for technical and ergonomic reasons.

Solution

A airbag situated in the seat pan deploys under frontal impact to hold the pelvis in place and prevent 'submarining'. This device was developed by Renault.

How it works
The seat bottom contains an airbag comprising two very thin metal sheets. This device is embedded in the foam of the seat cushion. Like a conventional airbag, this sandwich contains a gas generator that can be triggered to deform. By forming a hump under the seat, it prevents the pelvis from slipping forward. And due to the deformable sheet metal, it provides additional damping, thus complementing the action of the seatbelt.

Did you know?
In a collision, vehicle occupants (especially children) tend to slide underneath their seatbelt. This phenomenon, known as submarining, often results in injury to the abdomen, a particularly fragile part of the human body.
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Old 9th March 2015, 11:47   #51
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Default Re: Airbags: All you need to know!

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Originally Posted by knaveen View Post
Are these designed to protect pedestrians after hitting them?. Not sure if the force generated by a pedestrian will be sufficient to set of the airbag without being too sensitive.
These Pedestrian airbag sensors generally work on a different concept.

Unlike the regular sensors which sense displacement or acceleration pedestrian sensors work on the concept of pressure change.

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The earlier models used regular acceleration sensors to detect pedestrian collision, however they were not accurate enough to identify and differentiate between all types of impact whether human, animal or anything else.

Designers then came up with a new idea of adding a hollow tube inside the bumper, this tube would run from one end to the other end of the bumper in a continuous manner. These tubes were generally filled with air or some inert gas.

In case of an impact with a pedestrian the tube in that region would deform there-by reducing its cross-section area in that region and creating a pressure pulse which would travel through the tube and then would be eventually picked up by the sensor.

These sensors are calibrated such as to differentiate between an impact between a human and animal based on the size of the impacted portion.
e.g a human leg will have a concentrated point of impact when compared to a dog impact which will be spread over a larger area. Various other scenarios have been tested and a logic has been developed to identify various impacts, in-fact i know of Wild-boar and Deer impact study done as well in one of the vehicles

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The above image is one of the earlier designs of a pedestrian impact sensors.
The current design being worked upon which i know are based on small 0.5 inch diameter tubes embedded into the bumper foam with sensors located at either end(not at center as shown in image).
The advantage obviously appears in terms of weight savings and more accurate and quick response.
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Old 9th March 2015, 16:10   #52
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Default Re: Airbags: All you need to know!

"Submarining"

The first thought that came to my mind was a large inflatable float that erupts from the car roof if it is driven into deep water!

But seriously, I know what is meant, and it reminds me that I have known passengers who recline the seat for sleep during a journey. Without having the exact technical back-up knowledge, simple instinct tells me that this is so wrong and dangerous. The seat belt cannot hold them, any airbags will be in the wrong places.

My imagination gives me a picture of telescoped legs forced past a smashed pelvis into the body they used to be attached to. I really wish I didn't have that sort of imagination, but, on the whole, I think it helps to keep me safe.

Which reminds me: people reading this this thread, and wondering about airbags and seat belts should really google and read up about what exactly happens in car accident: to hands, arms, shoulders, chest, legs, knees, etc etc. Don't blame me if you then decide never to get in another car!
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Old 9th March 2015, 16:21   #53
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Default Re: Airbags: All you need to know!

Very interesting thread. Till now I thought airbags were only of 2 types, front and side airbags, did not know that there could even be airbags designed for pedestrians. Shows how much there is to learn and how much automotive safety has evolved. And yes Thad, after imagining the telescoped legs being forced past a smashed pelvis, I now understand the risks of an automobile accident a little more clearly.
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Old 10th March 2015, 19:30   #54
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Default Re: Airbags: All you need to know!

Came across this video of airbags. It shows the importance of timing of deployment of airbags (100th of a second ??)

So, always wear seat belts while driving, else you might encounter the second case highlighted in video!
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Old 10th March 2015, 20:42   #55
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Default Re: Airbags: All you need to know!

Quote:
Originally Posted by Rollingwheels26 View Post

1) Torso Protection Side Airbags:


While most cars in India have the these Chest Side Air Bags (SABs) mounted on the seats




,in some countries they are mounted on the car's doors.




A small clarification regarding the side airbags.

All cars have side airbags mounted in the Seat and on roof rails. It's only convertibles which have them mounted on the doors for obvious reasons since there is no roof to support it.

Design of door airbags is very tricky since it has to deploy in upwards direction against gravity and there is high possibility that the occupant might miss it. A lot of work is going on it, such as multi chambered airbags which helps in maintaining a pre-defined inflation pattern.
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Old 10th March 2015, 22:40   #56
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Default Re: Airbags: All you need to know!

Quote:
Originally Posted by Gaur View Post
A small clarification regarding the side airbags.

All cars have side airbags mounted in the Seat and on roof rails. It's only convertibles which have them mounted on the doors for obvious reasons since there is no roof to support it..

Er i think you are getting confused between thorax protection side airbag and head protection side airbag. In non convertibles the head protection side airbag is always mounted on roof rails. But the thorax protection airbag can be on the seat or the door(see the picture in my post showing the airbag deploying from door-it's a sedan with fixed roof) depending on the manufacturer’s call.

In convertibles either the manufacturers go for a combined thorax+head protection airbag which is quite large and deploys mostly from seat OR if they go for separate airbags for head and for thorax then the thorax airbag is mounted on seat and the head protection from the door.

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Old 11th March 2015, 09:38   #57
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Default Re: Airbags: All you need to know!

@Rollingwheels26 You are right, got a bit confused about it.

Once again regarding the thorax airbags, as far as I know the current practice is that almost all new vehicles have them mounted in the seats.

It was a few initial models which had them placed in the door trims.
There were 2 main disadvantages if it.

1-- In case of side crash the occupant would move away from the crash zone along with the seat, the relative displacement between the door trim and the occupant is not same and the occupant may loose contact with the airbag inflating from the door trim, however in case of the airbag mounted on the seat, the movement of the seat and occupant will be same as the occupant is secured to the seat with seat-belts, in this case the airbags deploying from the seat will also move along and will always act as a barrier between the occupant and intruding parts.

2-- The other problem is of Design complexity and cost.
The deployment of airbag from the door trims is very complex also the cost of fitting airbag in door is also very high when compared to seat mounted airbags.
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Old 21st February 2016, 19:18   #58
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Default Re: Honda recalls City, Jazz and Civic for Airbag defect

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Originally Posted by saket77 View Post
Hence, the recall is to replace the inflators only and not the airbags.
The inflator unit houses the folded/rolled airbag and the propellant chemicals required for the inflation. When they replace the inflators, they are essentially replacing the entire assembly.

Last edited by Gannu_1 : 21st February 2016 at 20:55. Reason: No longer OT. Removing those bits.
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Old 21st February 2016, 19:22   #59
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Default Re: Honda recalls City, Jazz and Civic for Airbag defect

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Originally Posted by Gannu_1 View Post
/OT



The inflator unit houses the folded/rolled airbag and the propellant chemicals required for the inflation. When they replace the inflators, they are essentially replacing the entire assembly.
No Ganesh! I have got them replaced. Only inflators are changed, not the airbags. I have shared the pictures and information in the other honda recall thread.
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Old 21st February 2016, 19:28   #60
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Default Re: Honda recalls City, Jazz and Civic for Airbag defect

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Originally Posted by saket77 View Post
No Ganesh! I have got them replaced. Only inflators are changed, not the airbags. I have shared the pictures and information in the other honda recall thread.
Saket, w.r.t. your post (Honda recalls 2.2 lakh cars (CR-V, Civic, City, Jazz) in India over faulty airbags) in the other recalls thread, this is the image of the co-driver side inflator unit which looks like a cylinder.

Isn't this unit housing the airbag as well? Are you saying there is a different unit that houses the airbags? As far as my understanding of this system goes, the inflator assembly holds the airbag and the propellant chemicals required for the inflation.

Same goes for the driver side inflator unit (image you had shared) which is located in the steering wheel boss.

EDIT: I stand corrected. Did some digging and came across these cross section images of the co-driver side inflator:

Airbags: All you need to know!-takata_airbags-1.jpg

The fabric seems to be located outside of this inflator. Thanks for this Saket!

Last edited by Gannu_1 : 21st February 2016 at 19:51.
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