AFM measurement/backpressure

[Bernd Felsche]

Greg Hermann writes:
>>At 09:34 11/03/00 +0800, Bernd Felsche wrote:
>>>>>None that I can recall.  Lucas/Bosch systems use them, and
>>>>>patent leasees of them.

>>>>>Numerically probably MAP is most common, then hot wire, and
>>>>>then combos of MAP/hot wire.

>>>>So what is the best way?? The rover system uses MAP and inlet
>>>>air temperature...

>>>Even hot-wire is passé. :-)

>>How does hot wire work?? Is is a little heater that uses X power then you
>>measure the temperature... more airflow the more heat is taken from the
>>heater?? Surely you would also need air temperature, or am I completly off...

>The resistance of the wire varies with its temperature, so one approach
>would be to measure the voltage required to hold the wire at a constant
>current. The more air flow you have at a given IAT, the cooler the wire
>gets.

The current flow is directly related to the *mass* of the air
flowing in. That is generally sufficient to determine the amount of
fuel to inject.

If you however desire air temperature - e.g. to adjust spark timing
or to alter the injection to allow for vapourization in cold air,
then you must sense this separately.

-- 
Real Name: Bernd Felsche
    Email: nospam.bernie at perth.DIALix.com.au
     http://www.perth.dialix.com.au/~bernie - Private HP
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