piston valve without pilot-waste..

[Brian the brain]

Well
In my quest for the ultimate repeating piston, used for higher pressures, I came up with this.( I have acces to a metal lathe)

The basic idea is, a hammer valve actuated piston valve, but one that is just as easy to hammer at 100 psi as it will be at 600.

Another thing is...I didn't like the idea of waisting the pilot volume without any benefit.THis decreases the number of shots from one tank significantly.

I thought of directly dumping the pilot in front of the piston, by running the hammervalve rod through the piston.
In theory, the increase in pressure from the front should even help the piston slam back quicker.
Two O-rings keep it airtight, 2 springs ( could be reduced to work with only one) keep everything in place.

One condition is, the pilot area needs to be able to equalise.So the piston doesn;t even need additional O-rings..

Tell me what you think.

[jrrdw]

So your saying the pressure from the shot would re-equilize the pilot chamber? Or that's the vent?

[Brian the brain]

The vent.

\once the piston slams back, the hammervalve rod-thing, whatever you want to call it shuts off and after that the piston does too.


Just a more efficient way of piloting a hammer valved piston, with no real pressure limit the hammer has to overcome..

[MRR]

Veeery cool idea! That is definitely worth a try.
If I get it right from the diagram then you vent with a hammer hitting the bolt, the piston strikes back and reset the hammer to firing position again.

[Brian the brain]

Yes.
You could include a nut to have a point for the piston to push against, or just use the spring.

Use the spring to both close the piston and push the bolt into closed position on the other end.

That would be coolest.

It needs to be slammed shut or it might end up honking the valve until the chamber is empty.

[POLAND_SPUD]

I don't get it.. and since it doesn't happend very often it might be a good idea to explain it more or put an animated diagram...

well I know what you mean and how it is supposed to work but I don't know how this happends...

anyway.. seems like a nice try but I am not quite sure if directing air infront of the piston will really improve performance and whether it would be cost efective... (I assume that the projectile will move when you pilot the gun... also there is a chance that the valve would open slower than a comparable traditional piston valve......

and finally, let's assume that the gun would use ~5% less air for each shot.. would you still consider it as worth building ??)

[psycix]

Good concept.
Note that the hammer will be pushed backwards as soon as it is opened.
The hammer has a hole in the front, but none in the back (on the side doesnt count). It will try to return to its original position.

[Brian the brain]

also there is a chance that the valve would open slower than a comparable traditional piston valve......

I very much doubt that.The forces that keep the piston pressed against the barrelport are instantly reversed.

It doesn;t need to open faster, it might, but it doesn;t need to

the reasons I find it worth trying are the possibility of high pressure hammering, and the idea of not wasting the pilot volume for nothing.

[jrrdw]

To build this in a clear tee would be awsome! With all parts brightly colored to make them stand out.

[jean]

hi im working the last weeks on an co2 plinker and build this valve
is really easy to buil an nice to shot @high pressure

by jean

[Brian the brain]

That's.....nice.....jean...


JSR proposed the sear thing a couple of years ago.

@jrrdw:
Any piston valve is cool when you can see inside...


Can anybody spot an error in the design?

No further comments??

[psycix]

Nope. Lets build it!
My university's machine shop will be overcrowded in a few weeks (48 groups of 8 students building 48 vehicles for a project) so if you want something, it'll gotta be within two weeks.

[Gippeto]

Jean, a hammer actuated piston valve, I LIKE it! I may tweak this a bit and use it in the future, thanks!

As to your design Brian, I don't see any major problems.

A suggestion to limit the pilot volume though. A "spring guide", or tube, running around the pilot valve, and inside the spring would take up some space.

[Brian the brain]

Thanks.
You can be sure I'll keep the pilot to a minimum.It's just a sketch, so it's not to scale.THe spring should be just big enough to hug the center rod, and it should fit snugly into the piston.

That would do it.

I'll build it when I have the time.
To everyone: feel free to build and use it if you can.
Adapt the design if you think it's needed.