Author Topic: Auto Shut Down  (Read 39189 times)

dkwflight

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Re: Auto Shut Down
« Reply #90 on: May 10, 2006, 01:35:09 AM »
Hi Have you guys looked at the Arrow engine overspeed mechanism? It apparently is a spring loaded stud. When an overspeed condition happpens the centrifugal force compresses the spring alowing the stud to extend and hit a lever.  I am not sure what the lever does but the Arrow is a spark ignition gas engine. The lever is an over center devise and has to be reset after coerrectins have been made and the engine restarted.

The detroit 2 cycle engines have a flap that when unlatched the springs force the flap to close the air intake. a system like this would stop a lister even with the rack all the way to the full speed position. a condition that could happen when a pin falls out.
Dennis
« Last Edit: May 12, 2006, 02:02:12 AM by dkwflight »
28/2 powersolutions JKSon -20k gen head
Still in devlopment for 24/7 operation, 77 hours running time

GuyFawkes

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Re: Auto Shut Down
« Reply #91 on: May 10, 2006, 02:42:07 AM »

The detroit 2 cycle engines have a flap that when unlatched the springs force the flap to close the air intake. a system like this would stop a lister even with the rack all the way to the full speed position. a condition that could happen when a pin falls out.
Dennis

all I've ever seen those sutters used for is keeping crap out of the blowers when servicing the intercoolers and turbos.

unless your blower seals were in good nick closing the flaps would such them and their oil in too

detroits scare me, maye they wouldn't if i'd done the factory course, but that whole convoluted rack / injector thing is sooooooo easy to get wrong, or make wrong with a light hammer blow

listers have an almost exposed valve chest, so undo one handscrew, pop the cover off and whack the collets right and the valve will drop down and decompress the whole engine >;^)

on a more serious note, there is SOMETHING THAT NEEDS TO BE SAID here.

these old style external flywheel motors have abso-fucking-lutely massive inertia in the flywheels when spinning at 650 RPM.

you think a 2" dia crankshaft is tough?

I wouldn't try dumping all that inertia quickly, eg breaking a pushrod, it would be tantamount to sticking a fire hose in the intake, sure it'll stop the engine, but it better blow a neat hold through the piston crown because if the piston or rod tries to sieze that 2" crankshaft will snap like a glass rod.

shutting the rack is nice, and shutting the rack and decompressing (assuming your listeroids are set so you can do that at speed without crowning the valve?) is very nice

nothing that stops (eg 0 rpm) the motor in less than fifteen seconds will be nice

if the listeroid design follow the lister then the only way you'll get a diesel fuel runaway is if the rack is wide open

if you have a lube oil runaway (from oil bath air filter or passing rings) then shutting the fuel won't shut her down anyway, listers run on minute amounts of fuel.

if you have a lube runaway then you, by definition, cannot cut off the "fuel", so you can only cut off the oxygen, either by sealing the intake, or flooding it with co2, or by closing the intake and exhaust off together

if you're running a gen head then overspeed also = over Hz, which will probably trip out your loads, and let the engine spin even faster, the beauty of the start-o-matic was the combines Ac/DC head, even if ac tripped out overspeed, dc was still produced and dc solenoid was the standard shutdown method.

so you want.

1/ auto shut down the works
2/ auto shut down that does not interfere with or over ride run away shut down
3/ run away shut down that doesn't depend on anything except the engine, eg not ac only gen head

so

1/ auto shut down can work happily by controlling rack and / or decompressor
2/ run away shut down can work happily by closing intake

item #2 is faily easy to make up, and fairly cheap.

on the air intel, most people fit a 90 degree elbow up to an air filter, don't, fit a tee, make sure it is a reducing tee, like this



this is a slightly exaggerated example

the small diameter should fit the lister intake.

now all you need is a lathe and a surplus ball bearing.

make and insert a seat (for the ball bearing) in steel, set it at the lister intake end of the tee and spot weld into place.

on the top of the tee goes your air filter as usual

in the other end of the tee in direct line from the lister intake you put your ball and actuator, eg a suitable spring, end cap and release mechanism (you could make a piston type plug out of brass rod instead of using a bearing)

TRY THE BLOODY THING ON THE BENCH, both at room temp and at least 150 celcius to make sure it don't sieze, you'll also have to keep that thing clean from dirt etc so the ball can't get hung up, just a little though will do.

don't make it do it as a perfect seal, you NEED a moderate amount of leakage, say 1 cm square, to prevent damaging the engine by turning it into a vacuum pump on the induction stroke, she won't run fast on an intake 1cm square

if you try and turn it into a vacuum pump you cut off cooling air and may make her suck past the valves

if you try it on the exhaust side you risk popping the head or piston

make sure the tee is THICK walled, so it doesn't break and open up the intake again

personally I'd trigger it by intake manifold vacuum.

if you do NOT run an oil bath air cleaner, the only way to get "fuel" up there is past the rings, so an "overflow" in the crankcase would stop dilution, which would stop spattering excess up the bore, and a very lightly spring loaded alloy crank case door would stop excess crankcase pressure from blowing anything up there, but neither of these will help if something goes wrong and the rack jams open***

***I can distinctly recall and enamel coffee cup vibrating off an old tangye, and being batted by the spokes straight into the governor linkage, which luckily is bent shut, not open.... most embarrasing as it was my coffee
--
Original Lister CS 6/1 Start-o-matic 2.5 Kw (radiator conversion)
3Kw 130 VDC Dynamo to be added. (compressor + hyd pump)
Original Lister D, megasquirt multifuel project, compressor and truck alternator.
Current status - project / standby, Fuel, good old pump diesel.

BruceM

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Re: Auto Shut Down
« Reply #92 on: May 10, 2006, 05:10:15 AM »
Very strange about the difference in governor forces between my Metro 6/1 and the original Lister SOM.  I wasn't blowing smoke, I really did measure mine.  Even stranger that Andre thinks his forces are nearly as low as the SOM.

Unless there are radically different governors???

I had previously thought the Start O Matic must have a HUGE solenoid!

A deompression pin well designed shouldn't require a lot of force, since it is extended and doesn't have to lift the valve.  I had already designed mine as a valve lifter before realizing that the  SOM always used the decompressor for shut down, so it was always already engaged with the engine stopped.

I don't see any need for a processor if only auto/emergency shut down is to be implemented. All that's needed is a timed relay for the shut down mechanism (if it needs one).

Bruce M








GuyFawkes

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Re: Auto Shut Down
« Reply #93 on: May 10, 2006, 11:33:47 AM »

I had previously thought the Start O Matic must have a HUGE solenoid!



not really, considering the built like a tank to last 100 years general ethos of the lister

--
Original Lister CS 6/1 Start-o-matic 2.5 Kw (radiator conversion)
3Kw 130 VDC Dynamo to be added. (compressor + hyd pump)
Original Lister D, megasquirt multifuel project, compressor and truck alternator.
Current status - project / standby, Fuel, good old pump diesel.

Andre Blanchard

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Re: Auto Shut Down
« Reply #94 on: May 10, 2006, 01:15:18 PM »
Very strange about the difference in governor forces between my Metro 6/1 and the original Lister SOM.  I wasn't blowing smoke, I really did measure mine.  Even stranger that Andre thinks his forces are nearly as low as the SOM.

Unless there are radically different governors???

I looked at it some last night, still no measurements, could not find a scale. :(
The times before when I pushed on the rack must have been with the engine running.  Engine running it takes very little force to push the rack closed but with the engine off it takes a considerable force ~10lbs or so.
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Andre' B.
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Andre' B

SHIPCHIEF

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Re: Auto Shut Down
« Reply #95 on: May 10, 2006, 07:06:55 PM »
The rack closing spring should be tripped with a trigger. Then the solonoid actuator doesn't have to be very strong, nor continuously energized.
The Inlet air flapper in Detroit Diesels is spring loaded and uses a small solonoid to trip the trigger.
It is used for over speed trip, low oil pressure, and high water temp if that is your desire, because a simple relay circuit energizes the solonoid.
Virtually every 2 stroke detroit has this setup under the air filter, as it shuts the air inlet to the supercharger. It is reset by rotating the flapper shaft and pulling the trigger back into the notch on the shaft drum. Once you see it the elegent simplicity is obvious. Once you get your mind around it, you can build one for linear actuators or rotatry ones.
The same could be applied to the decompressor(s). The tappet on the SOM is held up by inserting a wedge / pin. A small force pushes it under the tappet when the tappet flange is up, 5 time per second.

A lister can run on air sucked out of the crankcase, even with the inlet air totally shut off (ask me how I know) but it won't be running very fast, and it will smoke alot. Not an overspeed danger, but not satisfactory if you were using it as a low oil shutdown. The SOM has it right with two shutdown forms; fuel rack and decompressor.
Scott E
Ashwamegh 25/2 & ST12
Lister SR2 10Kw 'Long Edurance' genset on a 10 gallon sump/skid,
Onan 6.5NH in an old Jeager Compressor trailer and a few CCK's

BruceM

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Re: Auto Shut Down
« Reply #96 on: May 10, 2006, 07:28:18 PM »
I agree, Scott, the SOM approach is solid and simple- close the rack and decompress.
If the governor spring is released, that does the trick for the rack.  It could be done via a solenoid.

iI wanted auto start, too, thus the my pneumo rack closer (and decompressor).


GuyFawkes

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Re: Auto Shut Down
« Reply #97 on: May 10, 2006, 07:56:49 PM »

A lister can run on air sucked out of the crankcase, even with the inlet air totally shut off (ask me how I know)

How do you know?  ;D

this sounds like a good story

<fx> grabs popcorn, pulls up chair... </fx>
--
Original Lister CS 6/1 Start-o-matic 2.5 Kw (radiator conversion)
3Kw 130 VDC Dynamo to be added. (compressor + hyd pump)
Original Lister D, megasquirt multifuel project, compressor and truck alternator.
Current status - project / standby, Fuel, good old pump diesel.

Andre Blanchard

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Re: Auto Shut Down
« Reply #98 on: May 10, 2006, 11:17:32 PM »
I have seen an engine do that at a tractor pull, tractor was tweaked to abut 10 times factory HP.  Head cracked or gasket let go and the engine run away on the crankcase oil, not sure if the driver or the sled operator pulled the air shutoff but when everything stopped the engine was still running at about 150 RPM, big clouds of white smoke coming from places it's not suppose to come from.  It run like that for about 5 minutes until someone found a CO2 fire extinguisher.  Since then every pull in the area has at least two extinguishers along the track.
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Andre' B.
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Andre' B

oldnslow

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Re: Auto Shut Down
« Reply #99 on: May 11, 2006, 02:32:56 PM »
Yeah, Halon works like CO2 also.
Mistakes are the cost of tuition.

dkwflight

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Re: Auto Shut Down
« Reply #100 on: May 12, 2006, 02:01:31 AM »
Hi Yes that would be a positive shut down, co2 or nitrogen in the intake!
I dont think shutting the air intake off with a shutter would hurt the engine. The Detroit engines were not hurt when the shutter was popped.

I'm still thinking about what it would take to be 100% safe
1. overspeed shut down.
2. low oil = SD
3.High temp or low water = SD
4. Over or under volt = SD
All done as simply as possible = Reliability

Some time ago I read about an oil replenishment system to maintain oil at the right level.

Every one has taken a drink of water from a cooler that had a 5 gallon jug inverted in the top. I am thinking about a jug filled with oil inverted in a cup connected to the oil pan below the proper oil level. As the oil is consumed the level will drop in the crankcase and the cup. When the oil level drops air is alowed into the jug untill the level rises in the crankcase cutting off the flow of air into the jug. The oil goes in the other direction.

A similar system used a container that held oil. A vacum source was fitted to the container. The crankcase was over filled with oil. When the engine was started the vacum would pull the excess oil back into the container! The oil pickup had to be place where the oil level was wanted to be maintained. When the engine was stopped the oil in the container would draine back into the crankcase. This system worked properly when the engine was stopped and started regularly.

A pre-oiler sytem could be rigged with an oiling sytem, using a bottle that would be filled when the engine ran. A valve was used to hold pressure in the bottle. The valve would have to be closed after full pressure was developed in the engine.  When the engine was wanted the valve was opened the oil under pressure would be forced through the oil gallery to the bearings. I am not sure how well this would work with the listers limited oiling system. It would put oil through the squirt tubes to the bearings. It might be worth trying
Dennis
« Last Edit: May 12, 2006, 02:05:42 AM by dkwflight »
28/2 powersolutions JKSon -20k gen head
Still in devlopment for 24/7 operation, 77 hours running time

westexx

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Re: Auto Shut Down
« Reply #101 on: June 17, 2006, 05:57:17 PM »
I have an idea on high temp and low oil shut down that I would really like to get some advice on before I go full bore into it. I have a surplus Sterlco temperature control valve that is reverse acting set up for 185 to 225 degrees. The valve is made to control water temp in heat exchangers and tanks. I want to install the bulb for it in my return water line behind my thermostat. I know it needs to be ahead of the t-stat but bulb is 6” long. Using brucem’s idea with the air cylinders for fuel rack shutdown. The theory is that at 225 the valve will open letting stored air in to actuate the air cylinder for shut down or it can be set up to drain air out of a pre pressurized system releasing a spring loaded shutdown. I like the pre pressurized better because if you loose air it shuts down on its own and is just one more fail safe. I also thought about adding a shut down for the generator that would unload the power before the engine is shutdown with air cylinders. This could be managed with a flow control on the engine shutdown that let full flow to the generator disconnect and slower flow to the engine. Low oil could be handled similar with a mechanical air switch out of McMaster. The oil sump will need to be modified at the drain to make a none turbulent area for a float to stay calm during operation with the float actuating the mechanical air switch incorporated into the same air system as the temperature control valve. My intentions are to keep the system electrically free. All advice will be appreciated.         
Wesley   Ashwamegh 25/2

kyradawg

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Re: Auto Shut Down
« Reply #102 on: June 17, 2006, 06:49:00 PM »

Peace&Love :D, Darren
« Last Edit: August 03, 2006, 04:13:12 AM by kyradawg »

westexx

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Re: Auto Shut Down
« Reply #103 on: June 17, 2006, 07:25:28 PM »
Yes it would work with another air actuated valve but where would it need to go before the injector pump or after. I would think before the injector.
Wesley   Ashwamegh 25/2