hall effect crank sensor converter

[mefmotorsport]

Has anyone thought about a circuit to convert a hall effect crank sensor square wave signal to something that would work with the S40 input?

I'm working on a VW engine that has a hall effect sensor built into the rear crank oil seal cover looking at a 60-2 trigger wheel on the back of the crank. Id really like to keep this sensor as there's virtually no or little room for a front mounted trigger wheel sensor due to proximity of the chassis leg. The extra cost of an S60 is too much for this job!

I'm sure it must be possible to convert the square wave signal into say a triangular wave which might work? maybe a PIC or Arduino? I suppose a simple LC low pass filter would do it but not sure how that would perform over the wide frequency range that would be required ie 200rpm would be 200HZ to 8000rpm which would be 8Khz

Any thoughts?

[katana]

Don't flame me cos i'm not a sparks but isn't something similar occurring when using the 'clean digital' signal from a ECU to drive an old style rev counter. I seem to remember talk of using a relay coil or a 'choke' to give the 'dirty analogue type' signal?

[Alex DTA]

If that's an ABF engine, the crank sensor from a 1.8t or a VR6 is a direct fit. They're both magnetic.

We use a simple low pass filter on our test rig for the S40. Obviously not tested it in the real world but it works fine on the bench.

[mefmotorsport]

Alex, its an AFH engine, a Polo 1400 16V circa 1999, originally had a dizzy but no crank sensor. I fitted one from a 1 ltre Lupo engine but its a hall effect so no good with S40.

In the meantime I've managed to get the Ford Zetec one fitted in place, modified the sensor with a flying lead and cut back the connector part, soldered my wires to the pins. Its nice and compact and will do the job but I'd still prefer the one from behind the flywheel. I'm looking into using a Arduino to convert the square waves to a sine wave, nice little project!

Whats the one you mentioned look like and how does it fit?

Martin

[Alex DTA]

There's a retro fit part for those engines, but it does require removing the flywheel:

030103171k-seal-flange-for-crankshaft.jpg (30.92 KiB) Viewed 9639 times

1.8t looks like this:

$_1.JPG (11.22 KiB) Viewed 9639 times

I have the connectors in stock as well.

[Rob Stevens]

Is that trigger something you can supply Alex? I cant see how it works with the seal in the middle

[Alex DTA]

Nope, available from most VW places (TPS, GSF, etc). Or here:
http://www.volkspares.co.uk/view/seal-f ... shaft/9810

Sensor fits in the outside of the housing, where I've added a pretty arrow. Paint won't let me put it at a 45 degree angle, so pointing down will have to do.
The seal in the middle is the crank seal.

030103171k-seal-flange-for-crankshaft.jpg (32.26 KiB) Viewed 9627 times

[Rob Stevens]

Thanks, I'll have to have another look at how this might fit, I guess the sensor can only ever be accessed by taking the flywheel off, Hats off to VW for conjuring up money making schemes for dealers. And here is me starting an itch for an Audi RS3 ! Money pit?

[mefmotorsport]

This is the same as the one from the 1 litre engine, it fits the AFH engine but the sensor that comes with it is Hall effect. You can access the sensor without removing the flywheel as there's a part of the block that is cut back for clearance. I had to grind back an area of the AFH cast iron block to get the sensor to fit.

So Alex your saying that there is an alternative magnetic sensor aveolsble to fit in that housing, the one in your picture looks a bit bigger than the Hall effect one which has a stem of around 9mm diameter. I'll see if I can remove it and take a picture.

[Alex DTA]

I think there's a bit of confusion, as I wasn't clear above.
I've been offering two separate solutions.

The 1.8t/VR6 sensors are magnetic, and fit the ABF block, which has a hall effect sensor. I only offered those as I'd assumed an ABF block.

Then there's this adapter. I didn't know it was hall effect. I don't know if the 1.8t sensor fits.

I hope that makes sense.