Steve

The piston is connected rigidly to the valve by the blue rod?.... ie they move as one?.... It certainly looks like it would work to me.... the caveat being the volume available for the shot is just what is inside the valve.... That volume (and pressure) would have to be tailored for the job required....

Bob

...but only meant as a response to Rob's implied challenge.

To refine the idea a small step toward practicality, the length of the "valve" would probably need to be adjustable in order to adjust the setpoint pressure.

Steve

where the piston joined the connecting rod, or at the other end....

Bob

...sufficiently to allow the Valve to contact the Seat. Setpoint pressure is defined by the PSI required to develop sufficient Piston Force to balance the associated Spring Force, and that Force is equal to the Spring rate x the difference in length between the Valve and uncompressed Spring.

Therefore the only way to adjust the setpoint pressure, if the Spring (length and rate) and Piston (area) are given, is to change the length of the Valve.

Steve

Brain Fart.... Of course the position of the piston means nothing.... Yeah, you would have to change the spring stack length or valve length....

One cider is apparently one too many tonight.... LOL....

Bob

Steve

It seems that the spring force will change, say from a 3000psi fill to a draindown of say 2000psi fill, in the amount of 12pf if the conecting rod (or seal area) would be 1/8" dia. since the connecting rod end is exposed to the declining pressure of the reservoir.

Will that effect regulation accuracy?

...as small as possible in relation to the piston area, to minimize the "feedthru" of reservoir pressure into the output pressure. This consideration applies, of course to all single-stage regulators.

If, for example, the piston OD were 0.25" and the rod 0.062, the resulting 16:1 area ratio would imply 1psi of output variation for every 16psi change in reservoir pressure.

That's already not horrible, but you could probably do better. For example, since the connection rod is under tension at all times, perhaps music wire would be a better way to go than an actual rod. Assuming again a .25" piston and a 1500psi setpoint, Piston force would be of the order of 67lbs, so wire as small as 1/32" would suffice, suggesting only 1/64 feedthru.

Steve

I'll cop to being wore out and maybe brain dead after a few too many long days, but I dont get it

Wheres the hammer striking? On the stem the green seal is on? If thats true, what opens the gizmo on the left? wheres your air coming from?

I suspect it wont be so mysterious after its explained, but for now....

 

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...to admit air from the reservoir into the firing chamber until pressure on the Piston overcomes the Spring and closes the regulator Valve.

The hammer (coming from the right) hits the firing valve stem (connected to the green head) and opens it to fire, just as in a normal unregulated PCP valve.

Steve

The valve spring istself is set at a certain weight vs the face area to reg inletted pressure?


"i never was much for book learnin"

Adjusting set point for pressure requires telescoping and locking valve stem, or adjustable valve as you mentioned??


"i never was much for book learnin"

Steve

at the piston end. Then you can adjust it easily.

...up-close and personal with the striker. Other than that, I'm totally on board.

I.e.: I'm not.

Steve

Like you and a real machinist, maybe prod applicable with volume concerns?


"i never was much for book learnin"

http://www.airgunsofarizona.com/DiscoReg.htm

Steve

Yes but a drop in reg large valve combo may be fun..just a thought..its a good design, love to see a real one.



"i never was much for book learnin"

n/t

It does have a couple of nice features - like not needing a vent hole, since the li'l piston can sniff ambient air in the hammer tube.

It probably has a gotcha' or two that aren't immediately obvious. Nevertheless it (or something similar) may offer a fairly easy way to build regulation into ordinary PCP valves, with a minimum of fuss.

Steve

n/t