Sensor Question

Bernd Felsche bernie at innovative.iinet.net.au
Mon Dec 10 03:18:28 GMT 2001


Greg Hermann tapped away at the keyboard with:
> At 10:12 AM 12/10/01, Bob - Uni wrote:
> >GH> I didn't see crank angle on your list.
> >I was going to use the cam angle for that (actually, I was going to
> >rip the guts out of a distributor, whack in a chopper wheel and use
> >an opto setup)

> Hard to get much timing accuracy that way, 60 -2 tooth wheels for
> crank position seem to be the approach of choice lately.

Sufficient accuracy for an engine with inertia is possible with a
chopper arrangement (Hall effect is preferable to opto) combined
with some form of TPU or timebase in the ECU. As long as you have
2*N timing edges (N is number of cylinders), you can also pick up
any speed variation (torque fluctuations) and adjust to ambient
conditions.

> Seems to me that, other than the existence of canned code for 60-2
> wheels, that ring gear teeth ought to be able to do pretty well,
> acting in concert with two, three,  four, or six crank position
> sensors (depending on how many pots you are dealing with), and a
> cam position sensor. But, of course, this means three Hall effect
> sensor inputs. Doing all of the crank position work off of the
> flywheel pretty much eliminates torsion vibrations, and gear
> and/or timing chain lash as a source of error.

You mean the starter drive teeth on the flywheel for timing?

Even the manufacturers don't stoop that low.
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