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The Judge’s Auto-Valve idea.

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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The Judge’s Auto-Valve idea.

Unread postAuthor: judgment_arms » Sat Jan 26, 2008 12:41 pm

After working on this for better than two years now I think I’ve finally got something.

Ladies, gentlemen, and all the rest, I present to you the Raven Valve:

First let me direct your attention to the first picture, an animated gif.
That should tell you quite a bit, such as I run an unregistered version of Advance GIF Animator.

Now to explain the theory, let me refer you to the next, larger, picture.
Key:
Gray = PVC Pipe.
Red = Epoxy pistons on all-thread rod.
Black = main spring.
Blue = high pressure compressed gas.

Note: in the pictures there is no sear, in reality there would be two that ketch on the vertical red line.

The smaller piston on the bottom acts as a pneumatic ram as pressure builds it pushes back, first on the sear but once that is removed on the main spring, once the pressure in the valve exceeds that which can be over come by the spring the bottom piston pushes back the main piston. The main piston is forced back opening the valve, allowing the pressure to dump. Once the pressure has fall en for enough the spring returns the valve closed.

Now then in order to keep the valve from farting there’s two sears, the main trigger sear and the bolt sear, as seen in picture 3.
Basically the gun only fires if:
The bolt is closed
The valve is pressurized
And the trigger is pulled

This valve was designed to work in conjunction with the G.A.R. System in my Auto-Cannon that I’ve dubbed “The Valkyrie Project”.

Questions, comments, and criticisms are welcome and requested.
Thanks!
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Attachments
Sears.JPG
Picture 3
the crudeness of this image resulted from the fact that it was 01:00hours when I drew the image
Sears.JPG (13.99 KiB) Viewed 360 times
Raven_ValveM1.jpg
Larger picture
Raven_ValveM1.jpg (16.41 KiB) Viewed 360 times
raven_anim1.gif
Animated GIF
raven_anim1.gif (14.16 KiB) Viewed 360 times
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Unread postAuthor: Lentamentalisk » Sat Jan 26, 2008 12:59 pm

I dont understand how the "bolt sear" works. How do you keep it from "farting" after each shot. the piston would not necessarily contract enough for the bolt sear to re-grab. Im sure you have figured out something to solve this, I just dont get it.
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Unread postAuthor: judgment_arms » Sat Jan 26, 2008 1:08 pm

Lentamentalisk, Main spring has got to be just strong enough to close the valve long enough for the bolt sear to latch. Hopefully all the air gets dumped then the valve closes, what would cause farting (now ain’t that a technical term) would be the valve closing building up just enough pressure to overcome the main spring and opening, then repeating. But since that requires the valve to close the bolt sear would ketch.
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Unread postAuthor: Lentamentalisk » Sat Jan 26, 2008 1:18 pm

well if the pressure is just on the edge of being released, then it will just dump a fraction of itself, then go back, and repeat, the sear wouldnt have time to latch, nor would it have closed suficiently for the spring to be able to latch. the piston would just wiggle back and forth across the very edge of where the air is released.

this would all be false, however, if after the air was dumped, the piston got enough momentum to carry its self back to the latch...
Im no expert on that sort of thing
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Unread postAuthor: judgment_arms » Sat Jan 26, 2008 1:26 pm

Picture it like this:
The valve is held shut by the sear, fully pressurized and ready to fire.
Sear is released allowing pistons to slid back opening the valve.
Valve depressurizes and main spring is able to push valve shut.
Main piston closes gap, pressure begins to rebuild, mainspring still strong enough to close valve.
Valve closes, bolt sear locks before pressure builds enough to over come main spring

By the way, I’m no expert either :)
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Unread postAuthor: jackssmirkingrevenge » Sat Jan 26, 2008 1:29 pm

It's conceptually identical to most of the auto pistons we had been discussing recently, which leads me to think it would suffer from the same "hanging" issue - once the firing valve is open, will the pressure in the chamber lower sufficiently to allow it to close again, or will it just hang open enough to let the air leak by. Perhaps it would be wise to include a cut-off valve that would close off the chamber from the air supply once the piston starts to move?
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Unread postAuthor: judgment_arms » Sat Jan 26, 2008 1:36 pm

*slaps head repetitively on hard surface*
Now I remember why there was a check valve in me original design.
Proves my point that my brain works best between 23:00 and 01:45…

Here’s my original design:
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Unread postAuthor: jackssmirkingrevenge » Sat Jan 26, 2008 1:53 pm

I'm not sure if the check valve would help in this case, the solution I'm trying in the design I'm currently building is to have the flow into the chamber physically opened by the piston only when it's fully closed.
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Unread postAuthor: judgment_arms » Sat Jan 26, 2008 2:20 pm

Looks to me that having the piston cut off flow wouldn’t do any good ‘cause once the air starts to bleed the valve would still close, opening he air intake and causing it to re-open repeating the whole dang process. In other words, it’s still going to fart.

And I see what you saying about me design, that cylinder is going to have to be weak or else it wont allow the thing to close… or it needs to disconnect from the rest of the system until every thing latches…
Oh yeah now I remember:
After the valve opens and all the air is bled off then the main spring can shut the valve. The mainspring is strong enough to overcome the firing cylinder up to 10psi. also I now recall why I left off the check valve.
It’ll take the valve awhile to refill because it the main chamber is 2” by 12” (the inner chamber that the firing piston rides in is 1 inch).
I’m looking at a ROF similar to the Bofors.

You’ll forgive my confusion; I’m trying to remember stuff I thought up at 01:00 in the morning, yesterday. (Stuff I really should start writing down.) :)
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