Odd Sensor Design

[Richard]

We have an engine model which is prone to a particular problem. When the
engine goes down after it fails a turbo charger, it slowly fills the
aftercooler and intake manifold up with oil. When the engine shutsdown, the
aftercooler drains the oil into the manifold. When a operator tries to
restart the engine, the cylinders fill up with oil (only after it actually
starts) then hydro locks and spits a connecting rod out the side of the
block. {yes, the engine generally starts fine with no hydrolock until it
starts coming up to speed, then it sucks the oil in and BAM!}

This is an industrial engine, which runs un-manned 24/7 and has a
shutdown/safety panel. We have several hundred of them.

What we're looking for, is some sort of sensor that can detect presence of
oil in the intake manifold. Oil can reach up to a 1/4" deep. We have a
port we can screw into, now we have to determine the best way of detection.

Since oil is a pretty good insulator, it will have an affect on what type of
sensor to use or design. Items we thought of....

Float style or tip level sensor - Hard to read a 1/4" level
Small, low temp hot wire, measure the current, if submerged in oil it may
change, vrs air/gas mixture
Capacitance measurement? - Possibly the best method???

The method can not cause combustion of a combustable mixture.
We have 24 vdc on skid.
Normal shutdown method is to pull down inputs from our panel (3.3 vdc TTL
with pull ups) grounding an input forces it low thus a fault.

Any clever ideas for this one?

Richard




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[s--p--o--n--i--x]

On Tue, 18 Jan 2005 06:05:46 -0600, "Richard" <rwskinner ATawesomenet
Dot net> wrote:

We have an engine model which is prone to a particular problem. When the
engine goes down after it fails a turbo charger, it slowly fills the
aftercooler and intake manifold up with oil. When the engine shutsdown, the
aftercooler drains the oil into the manifold. When a operator tries to
restart the engine, the cylinders fill up with oil (only after it actually
starts) then hydro locks and spits a connecting rod out the side of the
block. {yes, the engine generally starts fine with no hydrolock until it
starts coming up to speed, then it sucks the oil in and BAM!}

This is an industrial engine, which runs un-manned 24/7 and has a
shutdown/safety panel. We have several hundred of them.

What we're looking for, is some sort of sensor that can detect presence of
oil in the intake manifold. Oil can reach up to a 1/4" deep. We have a
port we can screw into, now we have to determine the best way of detection.

Since oil is a pretty good insulator, it will have an affect on what type of
sensor to use or design. Items we thought of....

Float style or tip level sensor - Hard to read a 1/4" level
Small, low temp hot wire, measure the current, if submerged in oil it may
change, vrs air/gas mixture
Capacitance measurement? - Possibly the best method???

The method can not cause combustion of a combustable mixture.
We have 24 vdc on skid.
Normal shutdown method is to pull down inputs from our panel (3.3 vdc TTL
with pull ups) grounding an input forces it low thus a fault.

Any clever ideas for this one?

Would a 'squing' sensor work?

 

[s--p--o--n--i--x]

On Tue, 18 Jan 2005 12:22:47 GMT, sponix@yahoo.com (s--p--o--n--i--x)
wrote:

Would a 'squing' sensor work?

This would be a good starting point:
http://www.solartronmobrey.com/products/level/point/minisquing.php

sPoNIX

 

[John Woodgate]

I read in sci.electronics.design that Richard
<rwskinner@ATawesomenet.Dot> wrote (in <41ecfca5$1_2@127.0.0.1&gt about
'Odd Sensor Design', on Tue, 18 Jan 2005:

What we're looking for, is some sort of sensor that can detect presence
of oil in the intake manifold. Oil can reach up to a 1/4" deep. We
have a port we can screw into, now we have to determine the best way of
detection.

Could you connect an oil-drain reservoir to this port, so as to drain
the oil away and eliminate the problem at source?
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Richard]

I'll look at the link you sent in more detail.
Thanks,
RIchard

Any clever ideas for this one?

Would a 'squing' sensor work?

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[Goran Larsson]

In article <41ecfca5$1_2@127.0.0.1>,
Richard <rwskinner ATawesomenet Dot net> wrote:

What we're looking for, is some sort of sensor that can detect presence of
oil in the intake manifold. Oil can reach up to a 1/4" deep. We have a
port we can screw into, now we have to determine the best way of detection.

If the port is below the expected oil level and it is possible to
attach a glass tube or transparent plastic tube to the port, then you
can either have the operator check for oil before starting engine
and/or use a simple optical sensor to disable engine start.

__________
/ \
| intake |
| manifold |
| |
\________ _/
| |
[| |] <-- optical sensor
| |
|X|
|X|
|X| <-- oil
|X|
|-| <-- drain


--
Göran Larsson http://www.mitt-eget.com/

 

[James Meyer]

On Tue, 18 Jan 2005 06:05:46 -0600, "Richard" <rwskinner ATawesomenet Dot net>
wroth:

We have an engine model which is prone to a particular problem. When the
engine goes down after it fails a turbo charger, it slowly fills the
aftercooler and intake manifold up with oil.

I would find the lowest point in the intake system where the oil can get
to and make a hole. Then I'd make a hole at a point in the intake way above the
highest level the oil can reach. Then I'd put fittings in each hole with small
tubes leading down to a sealed container just large enough to hold most of the
oil that leaks out.

That way the engine will be protected, it will always be able to start
and run, and the added container can have a normal float switch because, if it
is the right size and shape (taller than it is wide), the level change there
will be big enough. The float switch doesn't have to prevent starting, just
light a "check engine" light.

Jim

P.S. Two holes and two tubes are necessary so that the oil will flow easily
down the lower one while the air in the container can go back to the intake
through the upper one. No "oil lock".

P.P.S. Sometimes I'm so smart I amaze myself!

 

[Richard]

On this particular engine it's not possible. The aftercooler actually sits
in the intake so there is no way to catch the oil "before" it drains into
the manifold. Also, the manifold is integrated into the engine block "Vee"
and there are no taps anywhere low enough that would allow that.

That actually was our first idea, until we looked closer.

Thanks though,
Richard

Could you connect an oil-drain reservoir to this port, so as to drain
the oil away and eliminate the problem at source?
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

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[Boris Mohar]

On Tue, 18 Jan 2005 06:05:46 -0600, "Richard" <rwskinner ATawesomenet Dot
net> wrote:

We have an engine model which is prone to a particular problem. When the
engine goes down after it fails a turbo charger, it slowly fills the
aftercooler and intake manifold up with oil. When the engine shutsdown, the
aftercooler drains the oil into the manifold. When a operator tries to
restart the engine, the cylinders fill up with oil (only after it actually
starts) then hydro locks and spits a connecting rod out the side of the
block. {yes, the engine generally starts fine with no hydrolock until it
starts coming up to speed, then it sucks the oil in and BAM!}

Nasty problem. Google for capacitive oil sensors.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

 

Richard wrote:

We have an engine model which is prone to a particular problem. When
the
engine goes down after it fails a turbo charger, it slowly fills the
aftercooler and intake manifold up with oil. When the engine
shutsdown, the
aftercooler drains the oil into the manifold. When a operator tries
to
restart the engine, the cylinders fill up with oil (only after it
actually
starts) then hydro locks and spits a connecting rod out the side of
the
block. {yes, the engine generally starts fine with no hydrolock
until it
starts coming up to speed, then it sucks the oil in and BAM!}

This is an industrial engine, which runs un-manned 24/7 and has a
shutdown/safety panel. We have several hundred of them.

What we're looking for, is some sort of sensor that can detect
presence of
oil in the intake manifold. Oil can reach up to a 1/4" deep. We
have a
port we can screw into, now we have to determine the best way of
detection.

Since oil is a pretty good insulator, it will have an affect on what
type of
sensor to use or design. Items we thought of....

Float style or tip level sensor - Hard to read a 1/4" level
Small, low temp hot wire, measure the current, if submerged in oil it
may
change, vrs air/gas mixture
Capacitance measurement? - Possibly the best method???

The method can not cause combustion of a combustable mixture.
We have 24 vdc on skid.
Normal shutdown method is to pull down inputs from our panel (3.3
vdc TTL
with pull ups) grounding an input forces it low thus a fault.

Any clever ideas for this one?

Thermistors are good for this sort of work - read their resistance when
they are dissipating 10uW (0.01C of self-heating in air) and again at
1mW (1.0C of self-heating in air) and if you can't detect a 4% lower
resistance at the higher dissipation, the thermistor is immersed in oil
or water ...

Betatherm make mounted thermistors specifically for this sort of job

http://www.betatherm.com/products/index.php?pc_id=3b&pc_sub_cat=Instrumentation%20Probes&pc_sub_sub_cat=Liquid%20Sensing%20(Immersion)
--------
Bill Sloman, Nijmegen

 

[CBarn24050]

Subject: Odd Sensor Design
From: "Richard" rwskinnerATawesomenet Dot net

What we're looking for, is some sort of sensor that can detect presence of
oil in the intake manifold. Oil can reach up to a 1/4" deep. We have a
port we can screw into, now we have to determine the best way of detection.

I developed a thermister based level detector for a long extict project, if you
could get a suitable thermistor it could be finished to suit your purpose. If
you cant find an "off the shelf" device email me your address and i'll send you
1 for evaluation.

 

[Phil Hobbs]

CBarn24050 wrote:

Subject: Odd Sensor Design
From: "Richard" rwskinnerATawesomenet Dot net


What we're looking for, is some sort of sensor that can detect presence of
oil in the intake manifold. Oil can reach up to a 1/4" deep. We have a
port we can screw into, now we have to determine the best way of detection.


I developed a thermister based level detector for a long extict project, if you
could get a suitable thermistor it could be finished to suit your purpose. If
you cant find an "off the shelf" device email me your address and i'll send you
1 for evaluation.

The thermistor idea is a good one, but probably requires a controller, due to
the wide temperature (and hence resistance) range of an industrial engine
manifold. You could instead do something with two (mildly) hot nichrome
wires, one near the bottom of the manifold and one half an inch above it.
Wire them in series, and measure the centre tap in a bridge arrangement--if
there's a significant imbalance, you have an oil problem. That method needs
only an amplifier and comparator, and will work over a 200C temperature swing
without too much difficulty. Thermocouples would work, but the signal will
be pretty small, leading to potential noise problems.

Cheers,

Phil Hobbs

 

[Mark Jones]

Richard wrote:

We have an engine model which is prone to a particular problem. When the
engine goes down after it fails a turbo charger, it slowly fills the
aftercooler and intake manifold up with oil. When the engine shutsdown, the
aftercooler drains the oil into the manifold. When a operator tries to
restart the engine, the cylinders fill up with oil (only after it actually
starts) then hydro locks and spits a connecting rod out the side of the
block. {yes, the engine generally starts fine with no hydrolock until it
starts coming up to speed, then it sucks the oil in and BAM!}

This is an industrial engine, which runs un-manned 24/7 and has a
shutdown/safety panel. We have several hundred of them.

What we're looking for, is some sort of sensor that can detect presence of
oil in the intake manifold. Oil can reach up to a 1/4" deep. We have a
port we can screw into, now we have to determine the best way of detection.

Since oil is a pretty good insulator, it will have an affect on what type of
sensor to use or design. Items we thought of....

Float style or tip level sensor - Hard to read a 1/4" level
Small, low temp hot wire, measure the current, if submerged in oil it may
change, vrs air/gas mixture
Capacitance measurement? - Possibly the best method???

The method can not cause combustion of a combustable mixture.
We have 24 vdc on skid.
Normal shutdown method is to pull down inputs from our panel (3.3 vdc TTL
with pull ups) grounding an input forces it low thus a fault.

Any clever ideas for this one?

Richard

Thread a little tube over to where the oil will most likely converge
and secure it somehow (magnets, epoxy, etc.) Then run this tube to a
small pump, like:
http://www.allelectronics.com/cgi-bin/category.cgi?&item=PMP-2

Pulse this pump every few minutes or so. A sensor in the "output"
vessel can then easily tell if any oil has accumulated and if so,
latch the pump on continuous and trigger shutdown - both removing the
oil and shutting down the engine.

p.s. I'm looking for work.


-- "If necessity is the mother of invention, then is experimentation
the father?" MCJ 20041116

 

[Richard]

"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:e2gqu0h0su3lv71le9kfehgnlh6id5k3gc@4ax.com...

What (approximately) is the temperature and pressure range at the
sensor? I think this could be done very reliably at a reasonable cost
using the thermal conductivity principle and Pt RTDs.

Wow, lots of good ideas. Manifold pressure can be as high as 20 psig with
the temperature ranging from 130-180 Deg F while running. We actually try
to hold it at 130F, but depending on load and ambient it can vary.

Thanks,
Richard




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[Rich Grise]

On Tue, 18 Jan 2005 06:05:46 -0600, Richard wrote:

We have an engine model which is prone to a particular problem. When the
engine goes down after it fails a turbo charger, it slowly fills the
aftercooler and intake manifold up with oil.
....
Any clever ideas for this one?

Yes. Diagnose what's causing the manifold to fill with oil, fix the
design, and quit trying to work around a built-in malfunction.

Good Luck!
Rich

 

[Rich Grise]

On Tue, 18 Jan 2005 12:28:08 +0000, John Woodgate wrote:

I read in sci.electronics.design that Richard
rwskinner@ATawesomenet.Dot> wrote (in <41ecfca5$1_2@127.0.0.1&gt about
'Odd Sensor Design', on Tue, 18 Jan 2005:
What we're looking for, is some sort of sensor that can detect presence
of oil in the intake manifold. Oil can reach up to a 1/4" deep. We
have a port we can screw into, now we have to determine the best way of
detection.

Could you connect an oil-drain reservoir to this port, so as to drain
the oil away and eliminate the problem at source?

Wouldn't "eliminate the problem at source" involve something more akin to
determining what design flaw is putting the oil in its wrong place first?

Good Luck!
Rich

 

[Tony Williams]

In article <e2gqu0h0su3lv71le9kfehgnlh6id5k3gc@4ax.com>,
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:

What (approximately) is the temperature and pressure range at the
sensor? I think this could be done very reliably at a reasonable
cost using the thermal conductivity principle and Pt RTDs.

Automatic oil level checking in aircraft gearboxes, using a
screw-in thermistor assembly, is quite common. In this case
though the relatively thin film of oil might require the
sensor to be a film or mat, exposed to the oil but insulated
from the thermal inertia of the manifold.

--
Tony Williams.

 

[Richard]

Wouldn't "eliminate the problem at source" involve something more akin to
determining what design flaw is putting the oil in its wrong place first?

Good Luck!
Rich

I suppose that is the best method, however Caterpillar has worked on it for
about 4 years now. All Turbos eventually fail, so that is a given, and
redesigning the engine block and manifold, well, I doubt we will see that
ever happen. Problem is, we have very many of these model engines!





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[Richard]

Hmm. Remember the intake manifold is under a variable vacuum -
getting oil to flow into a resevoir (especially from an area of high
turbulence) may not be as simple as it sounds.

Also the OP has stated there is no room for fittings and hoses.

Fitting everything through a 0.25" orifice is a bit constraining (kind
of like being a feline gynecologist, I suppose). But that's what makes
it fun.

Well, I'm going to check back - this is my third post to this thread in
about five minutes - but my suggestion is, diagnose what's pumping the
oil into the manifold in the first place, and fix that. Band-aids suck.

Good Luck!
Rich

Oh, that is the easy part. Again, a turbo charger is prone to extreme temps
and speeds, they all wear out. Yes, prevenative maintenance can eliminate
much of this by taking axial and radial clearance measurements on a routine
basis and change "before" a failure, but not failures give you such an
advance warning.

Kind of like having a blow out on your vehicle. Sometimes you can prevent
it by keeping an good eye on your tires and properly maintaining them, other
times, it just happens. When it does, well, hopefully you can pull over and
change the tire, or to some people, they loose control and drive off a
cliff.

I don't consider a safety shutdown to save a $100,000 engine as a bandaid,
besides, there are approx. 40 total safety shutdowns for one of these
engines. Surely they aren't all considered bandaids. They are there to
shut the engine down in case something is abnormal or something breaks.
Since they are industrial engines and run un-manned they are needed.

I guess we could take all the safeties off, and then have Cat build a
perfect engine. Heck, then we wouldn't need technicians <grin>.

RS




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[Goran Larsson]

In article <pan.2005.01.19.04.03.38.576440@example.net>,
Rich Grise <richgrise@example.net> wrote:

Wouldn't "eliminate the problem at source" involve something more akin to
determining what design flaw is putting the oil in its wrong place first?

The OP wrote that the oil problem is caused by a failed turbo. The
bearings in a turbo is commonly an oil bearing and if the bearing seals
break the turbo will leak oil into the air ducting, e.g. the wrong
place. Things do break in real life and failures aren't always caused
by a design flaw.

--
Göran Larsson http://www.mitt-eget.com/