Emergency shutdown method

[carbon-rod]

Hello all,

I just purchased my first jkson listeroid 6/1 from ozlisteroids, it won't be getting here until sometime in January but I thought I would start working on some things before it arrives....

I am thinking about using a servo to control the fuel rack however I also want a fail safe option to shutdown the engine if crap hits the fan or the servo fails for whatever reason. I see two main options, removing decompression and removing oxygen. I am thinking about putting a flap on the intake which is held open by a solenoid which will close and starve the engine when turned off, however I do not know the consequences of doing such a thing, would it suck oil up into the chamber past the rings if there was too much vacuum?

What do you guys think of this idea?  I know Bob B has installed a CO2 system for emergency shutdown however this is a bit too elaborate for me to take on at the moment!

Thanks!

Murray

[dieselgman]

Large ball valve on inlet port? Shutting down inlet air is how Detroit Diesels manage emergency shutdown. Too high vacuum is only momentary and should not affect anything adversely. I doubt that a runaway would be likely with a 6/1 but possible if you had a major malfunction or excessive wear on rings coupled with excessive crankcase splash. There are some threads posted dealing with options to handle such an instance. Decompressing will halt the engine but it could be at the expense of your exhaust valve.

dieselgman

[Simtech]

I also dont have a 'roid in hand yet, but I've given emergency shutdown for an overspeed condition a bit of thought; what I've come up with is a (properly counterbalanced) spring loaded weight on the flywheel that would hit a lever and trip a mechanical intake valve closure.

I'd much prefer a purely mechanical emergency shutdown in case of a catastrophic event like a lightning strike that would take out electrical components.

There's a HUGE amount of energy stored in the flywheels.

[Tom Reed]

Just thinking out loud here, but a CO2 fire extinguisher might be a real economical way to to.

[carbon-rod]

Dieselgman as long as I am not going to damage anything by the vacuum pressures, I guess the main combustion chamber is well suited to compression so I guess vacuum can't be too bad for it. large ball valve would be nice, I think I will make an inlet which then goes to a sealed air filter and when I need to shutdown just close off the inlet with a simple flap mechanism, which is probably easier than trying to hook up a spring close ball valve etc.

Simtech I also want something that is relatively segregated from an electrical control system, I am hooking the solenoid up in a fail safe system where the solenoid must be energised in order to hold the intake flap open, as soon as power turns off the flap will fall down and close off the intake ( it could be spring closed as well ) from the electrical side I might even design a system which requires a continual heartbeat  pulseon the output of the microcontroller in order to keep the solenoid activated, that way if there is a hardware failure and the pulse stops then the intake will close.

The problem is I would need to flood the area with Co2 and have it in a contained environment, It would be good if I was working with gas or something or as part of a fire system but to shut down the engine itself I have a couple of more simple options which don't require a enclosed environment for emergency shutdown.

The controller will monitor the speed and temperature of the fuel and coolant as well as oil pressure, and if they get out of hand then the fuel rack will close, if the engine doesn't stop then it will trigger the intake flap to close.

[veggie]

I fitted my Roid with an intake valve as noted earlier by dieselgman.
A solenoid might be better, or perhaps a cable/rod attached to the valve lever so the user does not have to reach across the centrifugal plane of the flywheels in an overspeed situation. 

veggie

[carbon-rod]

ahh that looks great, and the ball valve is a lot smaller than I thought it would be.... The only reason I was thinking about using a solenoid is because as soon as voltage is lost on the small solenoid the flap will close automatically, I guess the same could be done with a valve by having a closing spring that will close the valve in the event that the solenoid turns off, I'm just worried about how much force would be required to open and close the ball valve, whereas a flap (like they have on truck exhausts to prevent the water coming in on a vertical exhaust stack) requires bugger all resistance to open or close...

That valve does look nice and neat though, probably a lot nicer than a flap would look.

[veggie]

Hey guys...
how about a cable actuate disc brake mounted on the crank extention?
Like the ones used on the heavy downhill racing bicycles.
It would probably overcome the 6 hp made by a 6/1 roid.
The user  could be off to the side when actuating it.

Veggie

[carbon-rod]

Now thats a good way to stop a run away engine.... when it goes into overspeed just hit the brakes!

[dieselgman]

Goofy as it may sound - I like it! 

dieselgman

[LincTex]

how about a cable actuate disc brake mounted on the crank extention?

It would have to be a very heavy duty brake assembly to handle the torque, and Also very complex - it is easiest to just shut off intake air. Like dieselGman says, look at the flapper in Detroit Diesels. Gravity operated, very simple, HIGHLY effective. No need to reinvent the wheel.

[carbon-rod]

just need a solenoid with a decent stroke and cheap... ive only seen little tiny ones around, they use long stroke solenoids on some engines dont they?

[dieselgman]

Woodward makes a full line in 12vdc and 24vdc with either (or both) push and pull functionality and long strokes.

dieselgman

[Lloyd]

just need a solenoid with a decent stroke and cheap... ive only seen little tiny ones around, they use long stroke solenoids on some engines dont they?

The stroke can easily be adjusted with a lever arm linkage. To match what ever your needs are.

Lloyd

[carbon-rod]

Excellent thanks dieselgman.. I found some on Ebay I will chase up...

Lloyd, the ones that I was looking at were too small even to connect through leverage... plus I want to have a spring on the flap to assist it in closing, it should work pretty good when I get it all setup I will post up some pics, it will be a while though as I will only receive my engine this month sometime.