Hi-resolution Crank angle sensor

[dn]

Peter Wales wrote:

> Ah ha, now I see it. However, getting an asymetrically toothed flywheel
> won't be easy. Would this still work if the pickup was moved away from the
> tooth to make only the peak of the tooth effective, thus changing the m/s
> ratio artificially.

In a nutshell, yes.  The distance from the sensor to the tooth will have
a dramatic effect on how much of the tooth's width the sensor "sees".
This adjustment could, in fact, be made either mechanically or electronically. 

> As a matter of interest the Nissan 300 ZX Twin Turbo distributor has 2
> sensors in it. One reads crank angle from the 360 lines on the disc and the
> other reads an encoded cylinder number from the 3 digit code. Japanese
> engineering!

I was actually surprised that no one was doing this. (until now, that is) 
This is a combination of a relative position sensor (the 360 lines) and an 
absolute position sensor (the 3 digit coded portion of the wheel)  There
are many examples of commercially available encoders of both types, but
to my knowledge there is no combination of the 2 used in industrial
position sensing.  For a DIS type system, should be easy to substitute an
optical encoder for the guts of the distributor and get any timing accuracy 
you want.  Optical encoders are notoriously fragile, however, and you may
have a hard time finding one that will live a long and fruitful life in the 
underhood environment...


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 Darrell A. Norquay              Internet: dn at dlogtech.cuc.ab.ca     
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