AFM measurement/backpressure

[Bernd Felsche]

Ade + Lamb Chop writes:

>At 13:11 08/03/00 -0500, nacelp wrote:
>>> Do I get the impresion that AFM's in the USA are mostly the flap type,

>>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. :-)

The latest Bosch MED Motronic (for direct-injection (DI),
stratified-charge gasoline engines) uses a version of hot-film
(HFM5) that's sensitive to the flow direction. That's necessary with
the DI system because they run it with WOT at low loads, using
controlled, external EGR to reduce the engine's output - by varying
its displacement if you like.

MED also employs a MAP sensor to aid in selection of operating mode
for EGR. [More on EGR later.]

The engine is naturally-aspirated.

Ref.  Bosch "Ottomotor-Motormanagement",
	  1st Edition (1998)
      Dipl. Ing. (FH) Horst Bauer - Editor
	  ISBN 3-528-03877-2
	  !!! NB: German text.

If you're running a supercharger, then you need to know the manifold
pressure as it acts as a reservoir for air - you need to know how
much air is in there for transitional throttle response. You do need
to be aware of its limitations because of the pressure pulses which
occur as valves open and close - taking into account the delays
through the inlet tracts.

The mass-flow meter is _potentially_ more accurate for steady flow.

-- 
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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