crank position sensor

Tom Parker tparker at nznet.gen.nz
Mon Feb 8 10:08:58 GMT 1999


James Montebello <jamesm at talarian.com> wrote:

>There's a company in Canada called SDS (www.sdsefi.com) that sells a
>simple EFI setup. Their crank position sensor is simply a set of magnets
>on a crank pulley with hall-effect switches to detect them.  For a four
>with a 180d crank, you'd use two magnets to detect TDC (1&4 and 2&3),
>plus one extra magnet at TDC for cylinder 1 with a second trigger.
>Very simple to fabricate, provides a TDC signal for each cylinder,
>and moves the time between signals from the microsecond to the
>millisecond range.

Hmm... is two pulses enough? The computer doesn't get too much information
about the speed of the engine compared to 30 odd pulses that I've heard about.

At 3000 rpm, you have 600 pulses per second... I suppose that is quite a lot,
the computer should have a fairly good handle on the acceleration with that
many pulses.

Aranging two or four magnets on a pully wouldn't be too hard at all.

What advantages are there with having more pulses? Assuming that the pulses
from 4 magnets would be predictable, and evenly spaced around the crank.

How sound is this assumption, what would be necessary to ensure this? It's not
very good to have 1/4 a degree or two different from 2/3.

It wouldn't be too difficult to check with a timing light and calibrate the
software to compensate.

--
Tom Parker - tparker at nznet.gen.nz
           - http://www.geocities.com/MotorCity/Track/8381/




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