Balanced valve REVISION .. lets do it another way with advantages

[Motorhead]

The additional hole along the side of stem ( with stem also drilled ) had valve wanting to close much faster.  This compounded by the fact I use really light hammers that really don't have the mass / weight to hold the poppet off the seat for very long.  Adding more hammer weight tho LESS spring driving it is a work around to a heavily vented balance chamber IMO.  Sadly as hammer weight is increased you can get the valve to over dwell Very very easily.
JSAR uses a buffer to limit poppet lift height which is effective over a broad tuning range & power. ( kind of a do all design )

I really like a single venting path of less area using a lighter hammer and heavier spring driving it, then choke the transfer port to get a longer duration pressure rise within the throat which helps the poppet get a tad more dwell before the chamber comes up to pressure and poppet slams closed. ( This with a balance ratio more 60/40 ) being pretty easy to crack open.

Wish I had the time and fortitude in creating a cause & effect chart for these Reduced opening force valves. Charting out the cause and effect of Ratios of opening forces, effect light and heavy hammers have in achieving the wanted lift and flow without the valve over dwelling it self.    In my mind I have a pretty good grasp on the physics involved and understand too a point what is happening.  Sadly to really get a handle on all of this the parts and pieces thus far have needed to be custom purpose built.  These valves are Very very reactive in that one change effects another function or requirement much more so than a conventional knock open poppet valve.

[rsterne]

I'm not surprised that you are finding that with the short, large vent and small internal volume the "blow open" phase disappears in a hurry, with the result that you need more hammer strike to get back the dwell.... That is what I suggested would likely happen back in Reply #23.... A chart showing how all the various factors interrelate would be great, but I think it might end up being "valve specific", in that the trends would be similar, but a valve of different proportions might act quite differently.... At this stage about all we can reasonably expect is to get a handle on the trends, IMO.... Just too many variables....

The buffer is a great idea for a regulated PCP, and can be made to work unregulated as well (eg. bstaley mod)…. but it tends to knock the top off the power in either case (by limiting lift and dwell)…. It all depends on what you are after, efficiency and shot count, or lots of power.... as they are to some extent mutually exclusive.... and certainly the balanced valve design requirements are quite different....

Bob

[Scotchmo]

So a balanced valve is easy to open but getting the dwell correct can be a problem.

I'm thinking that a balanced valve combined with an electronic striker (solenoid) would be a great combination. The dwell of the solenoid is easy to control electronically.

We just need a balanced valve that opens easily and quickly. With sufficient valve spring to close it (not blow/stay open).

The solenoid plunger would need just enough momentum to crack the valve, and then just enough holding force to keep the valve open against the spring(s). The solenoid could have an adjustable millisecond timer in order to set the dwell.

The FPE is adjusted by setting the dwell. That would give the most efficiency possible, regardless of FPE settings.

Imagine a valve that fully opens easily and near instantly. It stays fully open only as long as we want it to. And then it closes instantly. That's what we could have.

[rsterne]

If you can get the resolution of the solenoid down to 10 microseconds or so, that could be a good solution.... The entire shot cycle is only 1-2 mSec.…

Bob

[PakProtector]

If you can get the resolution of the solenoid down to 10 microseconds or so, that could be a good solution.... The entire shot cycle is only 1-2 mSec.…

Bob

The solenoid coil firing voltage is variable. As is the capacitor properties and overall capacitance of the reservoir that will discharge into the coil. A film/foil affair is going to behave differently from an electrolytic, yes? Then we can also tweak the inductance of the coil. Am thinking it ought to be pretty low, and able to stand a substantial amount of amperage...which would be tuned by capacitance and firing voltage. We can for sure get a MOSFET capable of 100A to fire in well under a microsecond with a robust gate driver.

Just recall, there is no violating the conservation of energy; the hammer is fed from a battery. Lead-acid need not apply... But let's look at the numbers; a 3.5 A-h 18650 is going to be able to deliver about 40,000 Joules of energy. Even at 25% delivered to the hammer, that is 10,000 shots on a charge.

And then the usual suspects come into play, hammer mass top among them.
cheers,
Douglas

[Scotchmo]

If you can get the resolution of the solenoid down to 10 microseconds or so, that could be a good solution.... The entire shot cycle is only 1-2 mSec.…

Bob

The solenoid coil firing voltage is variable. As is the capacitor properties and overall capacitance of the reservoir that will discharge into the coil. A film/foil affair is going to behave differently from an electrolytic, yes? Then we can also tweak the inductance of the coil. ...

An advantage over strictly mechanical is that dwell does not depend on hammer mass. The valve can be held open electronically. Dwell is easy to control. I played with a 12fpe electronic build. An easy opening balanced valve would make the electronically controlled hammer more advantageous.

https://www.gatewaytoairguns.org/GTA/index.php?topic=96617.0

[int3man]

If you can get the resolution of the solenoid down to 10 microseconds or so, that could be a good solution.... The entire shot cycle is only 1-2 mSec.…

Bob

The solenoid coil firing voltage is variable. As is the capacitor properties and overall capacitance of the reservoir that will discharge into the coil. A film/foil affair is going to behave differently from an electrolytic, yes? Then we can also tweak the inductance of the coil. ...

An advantage over strictly mechanical is that dwell does not depend on hammer mass. The valve can be held open electronically. Dwell is easy to control. I played with a 12fpe electronic build. An easy opening balanced valve would make the electronically controlled hammer more advantageous.

https://www.gatewaytoairguns.org/GTA/index.php?topic=96617.0

If you guys want I can help with coils we wind our own at work.  The price is stupidly low.

Michael :- )

[Rob M]

If you can get the resolution of the solenoid down to 10 microseconds or so, that could be a good solution.... The entire shot cycle is only 1-2 mSec.…

Bob

The solenoid coil firing voltage is variable. As is the capacitor properties and overall capacitance of the reservoir that will discharge into the coil. A film/foil affair is going to behave differently from an electrolytic, yes? Then we can also tweak the inductance of the coil. ...

An advantage over strictly mechanical is that dwell does not depend on hammer mass. The valve can be held open electronically. Dwell is easy to control. I played with a 12fpe electronic build. An easy opening balanced valve would make the electronically controlled hammer more advantageous.

https://www.gatewaytoairguns.org/GTA/index.php?topic=96617.0

a solenoid directly driving the stem on a balanced valve might actually work.. might not even need a hammer mechanism... Assuming the poppet was soft enough to seal in a very balanced state ( like 85% ) .  Could be run by arduino and externally adjustable.. ( im getting carried away

the solenoid itself could reside in the tube , meaning a marauder would be an ideal base for less restriction on size. to add to this , I actually test some overbalanced valves, but when the seating force got too low , the valve would cycle itself

[Scotchmo]

If you can get the resolution of the solenoid down to 10 microseconds or so, that could be a good solution.... The entire shot cycle is only 1-2 mSec.…

Bob

The solenoid coil firing voltage is variable. As is the capacitor properties and overall capacitance of the reservoir that will discharge into the coil. A film/foil affair is going to behave differently from an electrolytic, yes? Then we can also tweak the inductance of the coil. ...

An advantage over strictly mechanical is that dwell does not depend on hammer mass. The valve can be held open electronically. Dwell is easy to control. I played with a 12fpe electronic build. An easy opening balanced valve would make the electronically controlled hammer more advantageous.

https://www.gatewaytoairguns.org/GTA/index.php?topic=96617.0

a solenoid directly driving the stem on a balanced valve might actually work.. might not even need a hammer mechanism... Assuming the poppet was soft enough to seal in a very balanced state ( like 85% ) .  Could be run by arduino and externally adjustable.. ( im getting carried away

the solenoid itself could reside in the tube , meaning a marauder would be an ideal base for less restriction on size. to add to this , I actually test some overbalanced valves, but when the seating force got too low , the valve would cycle itself

On my 12fpe solenoid gun with a conventional valve, I was never able to push the valve open directly. I only needed to give the plunger a running start of 0.09" before contacting the valve stem, though it worked best at about .120".  Even a little bit of momentum can make up for the high force needed to crack the valve.