Flywheel/Encoder patterns

[Mark Eidson]

Why not just have an encoder or sensor on the cam if you can get enough
resolution?    me

At 11:36 AM 12/6/96 MST, you wrote:
>
>>> 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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