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PICList Thread
'pic tachometer...for Diesel engine..'
1998\01\15@130046 by XYGAX

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Paint a white line on the flywheele and use one of those reflective opto
switches then count pulses it also has the advantage of being a non contact /
no mechanics interface

Cheers Steve.....

1998\01\15@174431 by Wim E. van Bemmel

picon face
Hello,

thanks .. I asked EXPERIENCE, no ideas untested ideas.

Sorry about beiing a little rude about this, but I think that if you dont make
your statement very clear you invoke a thread that leads to wonderful
discussions.. Goats.. Lawnmovers (sic) the "v" is meant as that.. Sometimes I
love them, and participate as well, but not if I have a serious thing to solve.
White lines do NOT stay white, and paint peels off in a seaborne environment.
Better is my idea of using Scotch or 3M reflective tape and use Infrared devices
through an infrared filter..  needs some cleaning now and then though.
Thank you all for the experiences you shared! They are useful, I'll try first to
get the RPM info from the alternator, and second best is the attack through the
valve rocker cover, I think. That way there are no crucial parts in dangerous
areas.
There was a response to my idea of using the injection pipe jerk.. did not fully
understand that answer.
For a quick hookup the approach of using the flywheel rim by inserting a magnet
or putting on a reflector seems to be the best. It gives a direct RPM info, no
calculations in the PIC to correct for the pulley diameters..
Thanks again, let us go to the original question, how to implement that in PIC.

XYGAX wrote:

> Paint a white line on the flywheele and use one of those reflective opto
> switches then count pulses it also has the advantage of being a non contact /
> no mechanics interface
>
> Cheers Steve.....

1998\01\15@174753 by peter

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face
XYGAX wrote:
>
> Paint a white line on the flywheele and use one of those reflective opto
> switches then count pulses it also has the advantage of being a non contact /
> no mechanics interface
>
> Cheers Steve.....

Most Industrial sensors don't respond above 500Hz
this is done to limit noise

--
If God so loved the World (and created it)
then why is it so imperfect
It's got more bugs than windoze 95

spam_OUTpeterTakeThisOuTspamcousens.her.forthnet.gr

1998\01\15@205607 by richard skinner

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face
Yes,  It was me with the rocker arm idea, and with the pulse on the injector
line.
I was a heavy equipment mechanic for a long time,  and the timing light we
had
used an inline pressure switch that activated the light.  I didn't like it
much
as we always had to have all kinds of adapters and such.  I normally just
set the engine crank where I wanted it,  then pressured up the pump and
rolled it
to point of injection, then tightened the pump coupling.  But any rate, back
to your
topic, the switch was sprung for Right below injection pressure,  It had a
very small
pin in a very small block, an adjustable spring (to control trigger pressure)
and a microswitch.
The pressure has to be very small so you don't take too much displacment from
the line, there
as affecting the timing.  We adjusted the spring until we had no reading,
then backed it off
just to where it would flash.  This would be right below injector pressure.
It worked great, especially
if we would have had only 1 engine to use it on.  But with anything from a
Komatsu to a Cummins or
Cat,  every line/fitting was different!

I heard of just a clamp on sensor that clamps to the outside of the line and
registered pulses, but
did not ever use one.  The spring loaded block would be real easy to make, if
you have access to
the tools.

Yes the alternator idea does work, but I have had bad experiences with it.
Belt slip,  alternator loosing
a diode and so on,  but, It makes one hell of a charging circuit warning
indicator,  in a boat, thats
manditory !!!!  <grin>



Richard Skinner
.....rwskinnerKILLspamspam@spam@worldnet.att.net

----------
> From: Wim E. van Bemmel <bemspanspamKILLspamXS4ALL.NL>
> To: .....PICLISTKILLspamspam.....MITVMA.MIT.EDU
> Subject: Re: pic tachometer...for Diesel engine..
> Date: Thursday, January 15, 1998 4:00 PM
>
> Hello,
>
> thanks .. I asked EXPERIENCE, no ideas untested ideas.
>
> Sorry about beiing a little rude about this, but I think that if you dont
make
> your statement very clear you invoke a thread that leads to wonderful
> discussions.. Goats.. Lawnmovers (sic) the "v" is meant as that.. Sometimes
I
> love them, and participate as well, but not if I have a serious thing to
solve.
> White lines do NOT stay white, and paint peels off in a seaborne
environment.
> Better is my idea of using Scotch or 3M reflective tape and use Infrared
devices
> through an infrared filter..  needs some cleaning now and then though.
> Thank you all for the experiences you shared! They are useful, I'll try
first to
> get the RPM info from the alternator, and second best is the attack through
the
> valve rocker cover, I think. That way there are no crucial parts in
dangerous
> areas.
> There was a response to my idea of using the injection pipe jerk.. did not
fully
> understand that answer.
> For a quick hookup the approach of using the flywheel rim by inserting a
magnet
> or putting on a reflector seems to be the best. It gives a direct RPM info,
no
> calculations in the PIC to correct for the pulley diameters..
> Thanks again, let us go to the original question, how to implement that in
PIC.
>
> XYGAX wrote:
>
> > Paint a white line on the flywheele and use one of those reflective opto
> > switches then count pulses it also has the advantage of being a non
contact /
> > no mechanics interface
> >
> > Cheers Steve.....

1998\01\16@012202 by Mike Keitz

picon face
On Thu, 15 Jan 1998 23:00:35 +0100 "Wim E. van Bemmel"
<EraseMEbemspanspam_OUTspamTakeThisOuTXS4ALL.NL> writes:
>Hello,
>
>thanks .. I asked EXPERIENCE, no ideas untested ideas.

>White lines do NOT stay white, and paint peels off in a seaborne
>environment.

Electric or magnetic is definitely the way to go.  Optical of any sort
won't like dirt and oil.  I suppose this could serve as a reminder that
it's time to clean the engine room.

Get the engine manual or talk to a dealer and see if there are any
'hooks' for a tachometer built in.   I'm sure it is a frequently
requested option.

Reluctance sensors based on Hall cells or coils biased with permanent
magnets can be used to sense virtually any moving ferrous part.  Examples
are gear teeth (is there a gear around the outside of the flywheel?),
bolt heads or corners on hex bolts or nuts, fan blades on the alternator
fan, rocker arms, etc.  They have to be mounted securely so the only
possible relative motion is from the part moving as intended.

It may be easier to attach magnets, etc. to the propeller shaft than to
the engine.   You may want to have tachometers for both the engine and
the propeller, if the transmission is of a type that can 'slip'.

When sensing the alternator frequency, use one of the stator phases
before the diode bridge.  It will swing from one diode drop below
"ground" to one diode drop above the positive battery voltage.  If the
diodes are external, it is very easy to make a connection to the proper
point.  Alternators for diesel engines may have it brought out already.
In fact, this signal may be already brought up to the control panel and
just left there for the optional tachometer.  Take a look for little gray
wires that don't go anywhere and/or RTFM.

Sensing the fuel injection could be done less intrusively by connecting a
low-pressure sensor to the fuel feed line between the filter and the
pump.  A periodic negative pressure should occur there as the pump takes
up fuel just before each injection cycle.  It may be very slight at idle
speed when very little fuel is being injected.

1998\01\16@054040 by GERRY COX

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face
XYGAX wrote:
>>
>> Paint a white line on the flywheele and use one of those reflective opto
>> switches then count pulses it also has the advantage of being a non
contact /
>> no mechanics interface
>>
>> Cheers Steve.....

>Most Industrial sensors don't respond above 500Hz
>this is done to limit noise
>peterspamspam_OUTcousens.her.forthnet.gr

Peter,
However, most diesel engines don't respond (for long)  above 500Hz * 60secs
= 30,000 RPM
This is also done to limit noise  :-)
Gerry Cox
----------

1998\01\16@073449 by kdowsett

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face
GERRY COX wrote:
>
> XYGAX wrote:
> >>
> >> Paint a white line on the flywheele and use one of those reflective opto
> >> switches then count pulses it also has the advantage of being a non
> contact /
> >> no mechanics interface
> >>
> >> Cheers Steve.....
>
> >Most Industrial sensors don't respond above 500Hz
> >this is done to limit noise
> >@spam@peterKILLspamspamcousens.her.forthnet.gr
>
> Peter,
> However, most diesel engines don't respond (for long)  above 500Hz * 60secs
> = 30,000 RPM
> This is also done to limit noise  :-)

Particularly the sound of bottom end bearing shells rattling around in
the sump.

> Gerry Cox
>  ----------

1998\01\16@165746 by peter

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GERRY COX wrote:
{Quote hidden}

Sorry I should have said response time of 1msec
which = max 500Hz given a symetrical input
under poor conditions less (dirty line/lens)

Paint half the flywheel white and half black
and it should work
but the fan would be close or past the limit

But the point that I'm making is that a standard sensor
has limits that WILL apply in this case

I HAVE use industrial sensors in similar situations
and I am aware of their limits

Peter
--
If God so loved the World (and created it)
then why is it so imperfect
It's got more bugs than windoze 95

RemoveMEpeterTakeThisOuTspamcousens.her.forthnet.gr

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