Flywheel/Encoder patterns

Walters Chris p23610 at gegpo6.geg.mot.com
Fri Dec 6 18:40:22 GMT 1996


>> I thought 60 was the practical limit on number of teeth on a timing gear 
 -
>> above that and you'd start to lose resolution.
>>
>> Rather than counting pulses, has anybody thought about encoding the 
timing
>> gear such that you can read crank position directly off the gear? Sortof
>> like a shaft encoder.
>
>The tooth wheel operates by generating an interrupt which in effect tells
>the processor the engine has advanced an X amount of degrees.
>Using the interrupt method is preferred because regardless of what is
>going on, the processor will stop what it's doing and attend to engine
>needs (i.e. load a counter, advance degree count, etc...).  If we do away
>with the interrupt, depending on what kind of calculations are being
>performed, system performance will suffer.  If we keep the interrupt
>(i.e. generate an interrupt based on encoder state change) what have we
>gained?  We still need the cam sensor to tell us if we are in power or
>intake strokes.

An encoder giving absolute crank position would implicitly supply an 
interrupt when the position changes value. Reading crank position directly 
means you wouldn't have to fool with timers or counters to derive it. You'd 
also know exactly what the position is upon start-up without having to store 
the last known position info upon shutdown. No way around the cam sensor tho 
that I can see.

Snake
no cool Fords yet, one cool Dodge



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