Air Bag Sensors ....how do they work?

[Derek]

I came across a damaged air bag sensor where I work (North America).
There are several of these mounted to various parts of the car. I had
always figured that they were a simple inertia or momentum type
switch that closed on impact. Inside is an IC with 32 pins and 6 very
small resistors and/or capacitors.

In simple, laymans terms, can anyone explain to me how an IC can
detect a sudden impact? What magic is this?

Thanks.

 

[Clifford Heath]

Derek wrote:

In simple, laymans terms, can anyone explain to me how an IC can
detect a sudden impact? What magic is this?

It's an accelerometer (acceleration sensor), possibly sensitive
in two dimensions, and made by Analog Devices or one of their
more recent competitors. Check out for example the ADXL202 device.

They have micro-machined working parts inside, etched into the
structure of the silicon, little arms extending between two fixed
structures. The chip measures the capacitance between these arms
and the substrate, and so measures the flexion.

 

[TonyP]

"Derek" <joe@hotmail.com> wrote in message
news:u3pl30pggdpspv056bm285n6shlercvq6k@4ax.com...

I came across a damaged air bag sensor where I work (North America).
There are several of these mounted to various parts of the car. I had
always figured that they were a simple inertia or momentum type
switch that closed on impact. Inside is an IC with 32 pins and 6 very
small resistors and/or capacitors.

In simple, laymans terms, can anyone explain to me how an IC can
detect a sudden impact? What magic is this?

Why does anything encapsulated in a plastic package with 32 pins, have to be
magic?

TonyP.

 

[Peter_purple]

TonyP wrote:

"Derek" <joe@hotmail.com> wrote in message
news:u3pl30pggdpspv056bm285n6shlercvq6k@4ax.com...
I came across a damaged air bag sensor where I work (North America).
There are several of these mounted to various parts of the car. I had
always figured that they were a simple inertia or momentum type
switch that closed on impact. Inside is an IC with 32 pins and 6 very
small resistors and/or capacitors.

In simple, laymans terms, can anyone explain to me how an IC can
detect a sudden impact? What magic is this?

Why does anything encapsulated in a plastic package with 32 pins, have to be
magic?

Thats all right he's from america and posting in an *australian* news group
not an Austin news group...

hehe

pp

TonyP.

--
that is because,

peter purple proclaims

The infamous big dollar scam list of email addresses, growing,
appended here for those nice news bots to collect their email addresses...

benjamin_cole2000@yahoo.com, williams_adebayo@hotmail.com, frpierrejr@yahoo.fr,
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<ahmedb@aol.com>,
<abanigo@justice.com>, <yusuf.mamman@telstra.com>, yusufmamman@fsmail.net,
akuwilly@fsmail.net, <douglaskwan@mail.com.fr>, douglaskwan@mail.com.fr,
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<ddlucian@libero.it>, tonyagha1@fsmail.net, tonyagha2@maktoob.com,
jerry brown <jerrybrown@fsmail.net>, <aceohale@hotmail.com>
haohale@hotmail.com, <alex.alex@alex4all.com>, <vanmannfred@fsmail.net>,
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Zenmo35@yahoo.co.in, <francis_ozo111@yahoo.com>, rayhadalihussein@gawab.com,
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mikeoyibo@indiatimes.com
sankoh.williams2004@laposte.net, abba_dabo1@freenet.de, pbenus027@yahoo.fr
mr_p_benus00tg@hotmail.com, momegoh66@hotmail.com, maomegoh65@hotmail.com,
jenet_01@indiatimes.com, jenet_01@ondikoi.com, nuwarsito44@netscape.net,
usman_alli@hotmail.com, usmanalli1@fsmail.net, zenmo35@yahoo.co.in

 

[Derek]

On Tue, 24 Feb 2004 15:49:26 +0800, Peter_purple
<purple@203.0.178.192> wrote:

TonyP wrote:

"Derek" <joe@hotmail.com> wrote in message
news:u3pl30pggdpspv056bm285n6shlercvq6k@4ax.com...
I came across a damaged air bag sensor where I work (North America).
There are several of these mounted to various parts of the car. I had
always figured that they were a simple inertia or momentum type
switch that closed on impact. Inside is an IC with 32 pins and 6 very
small resistors and/or capacitors.

In simple, laymans terms, can anyone explain to me how an IC can
detect a sudden impact? What magic is this?

Why does anything encapsulated in a plastic package with 32 pins, have to be
magic?

Thats all right he's from america and posting in an *australian* news group
not an Austin news group...

hehe

pp



TonyP.

Actually, North America includes Canada & Mexico.
I live & work in Canada, ....NOT Amrerica. Should have made that
clearer, didn't think it was important (most Canadians just live for
ice hockey, and buy/replace their electronic goods).

I enjoy reading this group and have been helped in the past, and there
are some very smart guys and colourful characters here.

Thanks, Clifford, for your insight, much appreciated.

Regards.

 

[Bob M]

Derek <joe@hotmail.com> wrote in message news:<le3n30pkdfi0ume8nahkr93e5udh6fs6vt@4ax.com>...

On Tue, 24 Feb 2004 15:49:26 +0800, Peter_purple
purple@203.0.178.192> wrote:

TonyP wrote:

"Derek" <joe@hotmail.com> wrote in message
news:u3pl30pggdpspv056bm285n6shlercvq6k@4ax.com...
I came across a damaged air bag sensor where I work (North America).
There are several of these mounted to various parts of the car. I had
always figured that they were a simple inertia or momentum type
switch that closed on impact. Inside is an IC with 32 pins and 6 very
small resistors and/or capacitors.

In simple, laymans terms, can anyone explain to me how an IC can
detect a sudden impact? What magic is this?

Why does anything encapsulated in a plastic package with 32 pins, have to be
magic?

Thats all right he's from america and posting in an *australian* news group
not an Austin news group...

hehe

pp



TonyP.

Actually, North America includes Canada & Mexico.
I live & work in Canada, ....NOT Amrerica. Should have made that
clearer, didn't think it was important (most Canadians just live for
ice hockey, and buy/replace their electronic goods).

I enjoy reading this group and have been helped in the past, and there
are some very smart guys and colourful characters here.

Thanks, Clifford, for your insight, much appreciated.

Regards.

Derek,

I too live in Canada (Mississauga, Ontario) and read this news group.
I have both received useful info when requested as well as shared my
Canadian 1/50 of a Loonie's worth of free advice. Lots of fun with
these guys. As a Canadian, I have just learned to accept that few
people can appreciate where "North America" REALLY is, as well as who
lives there.......

Cheers from Canada,

Bob M

 

[Des Bromilow]

If the only parts are a chip then it's some derivative of the Analogue
devices ADXL chips (micromachined silicon accellerometers) AD have a
wonderful paper on their site which shows how the micromachined beam
translates acceleration into a variable DC signal.

I tore apart the sensor out of a cherokee and found the "sensor" was purley
mechanical - A gold plated steel ball bearing, held captive in a tube by
magnets, and a pair of gold contacts at the opposing end where the ball
would close the contact. The magnet had been positioned to set a minimum
accelleration to release the gold ball.
Total sensor package was approx 40x40x80mm (1.5"x1.5"x3") as a metal case
filled with rubber.

HTH,
Des
"Derek" <joe@hotmail.com> wrote in message
news:u3pl30pggdpspv056bm285n6shlercvq6k@4ax.com...

I came across a damaged air bag sensor where I work (North America).
There are several of these mounted to various parts of the car. I had
always figured that they were a simple inertia or momentum type
switch that closed on impact. Inside is an IC with 32 pins and 6 very
small resistors and/or capacitors.

In simple, laymans terms, can anyone explain to me how an IC can
detect a sudden impact? What magic is this?

Thanks.

 

[Derek]

On 25 Feb 2004 07:56:58 -0800, bmorgoch@sympatico.ca (Bob M) wrote:

Derek <joe@hotmail.com> wrote in message news:<le3n30pkdfi0ume8nahkr93e5udh6fs6vt@4ax.com>...
On Tue, 24 Feb 2004 15:49:26 +0800, Peter_purple
purple@203.0.178.192> wrote:

TonyP wrote:

"Derek" <joe@hotmail.com> wrote in message
news:u3pl30pggdpspv056bm285n6shlercvq6k@4ax.com...
I came across a damaged air bag sensor where I work (North America).
There are several of these mounted to various parts of the car. I had
always figured that they were a simple inertia or momentum type
switch that closed on impact. Inside is an IC with 32 pins and 6 very
small resistors and/or capacitors.

In simple, laymans terms, can anyone explain to me how an IC can
detect a sudden impact? What magic is this?

Why does anything encapsulated in a plastic package with 32 pins, have to be
magic?

Thats all right he's from america and posting in an *australian* news group
not an Austin news group...

hehe

pp



TonyP.

Actually, North America includes Canada & Mexico.
I live & work in Canada, ....NOT Amrerica. Should have made that
clearer, didn't think it was important (most Canadians just live for
ice hockey, and buy/replace their electronic goods).

I enjoy reading this group and have been helped in the past, and there
are some very smart guys and colourful characters here.

Thanks, Clifford, for your insight, much appreciated.

Regards.

Derek,

I too live in Canada (Mississauga, Ontario) and read this news group.
I have both received useful info when requested as well as shared my
Canadian 1/50 of a Loonie's worth of free advice. Lots of fun with
these guys. As a Canadian, I have just learned to accept that few
people can appreciate where "North America" REALLY is, as well as who
lives there.......

Cheers from Canada,

Bob M

Greetings Bob, (from Windsor, Ont.)
And greetings as one boater to another.

Great bunch of guys on this group.

Cheers,
Derek.