SpudFiles

I hope this hasn't been suggested...

I thought it'd be cool to use a solenoid to activate a piston. It would allow you to fill from anywhere, and it would eliminate piloting completely! Also, it's my (probably flawed) understanding that it would activate really fast!

Here's a poorly drawn diagram:



Since I cant figure out Paint on Vista, I'll tell you what each color means.

Black: Pipe and other crap
Silver: Piece of iron or steel pipe
Red: Sealing face
Purple: Spring with a "k" just big enough to hold the piston sealed at 0 psig. Fairly thick wire, but low spring constant. Also inductive, such as copper. Is connected to the piston at one spot near the barrel, but the copper is more conductive. (hard to describe)
Blue: Wires to power source, probably a car battery. (100 - 200 amps)
Orange: STRONG bumper

The piston is as short as you want it to be, but the spring must still have a certain number of "turns" so that the solenoid still works. It doesn't need to move back FAR, but the whole point of this is to get it to move FAST.
The outer pipe is big enough to hold the spring, then reduces to the point where the spring is held, but the piston can move back. The spring is initially slightly compressed, and when the solenoid is activated, is even more compressed, so that the piston reseats after the current stops flowing.
The only problems I can think of are those I can't diagnose, i.e. I don't know much about electronics, or magnetic fields. I have a general idea of the concepts, but I'd need someone to crunch some numbers. Feel free to change any quantity to fit your needs.

Feedback and help are both appreciated!

Pilgrimman wrote:I hope this hasn't been suggested...
and it would eliminate piloting completely! Also, it's my (probably flawed) understanding that it would activate really fast!

Can you please elaborate more on this, I don't understand how this is supposed to work?

From what I know, (probably less than you) It looks like a good plan. test it and let us know.

You would probably need alot of coil, current and the other thing that makes solenoids more powerful I think coil and current helps, I can't remember it's the holidays

Anyway, if you manage to make a solenoid that can overcome the pressure behind it and still open with a decent speed, while somehow fitting it all in an air tight tee, then goodluck.

The metal rod has to actually be partly out of the coil for it to be pulled in when the coil is energised.

Technically possible if someone has the drive to do it

EDIT: Ignore this, Maxus edited his post


Either I didn't explain well (Probably) or I drew a crappy diagram (also probable). I've built two working piston guns, so I understand the principles of pistons.

Instead of the pilot creating a pressure difference that allows the piston to get pushed back , the solenoid "pulls" the piston back, against the force exerted by the spring. (I am probably erroneous in calling the pipe a piston in this case, but bear with me)

It seems from your post that you thought that this idea is intended to pilot a sprinkler valve. It is not a pilot. No air is wasted. The sealing face (red) is against the barrel (kept there by a slight force due to the compression of the spring). When the "piston" is "pulled" back towards the bumper (orange) by the solenoid, (the spring with a current flowing through it (purple)), the "piston" no longer seals the barrel.
If this is still confusing, I'll work on another, hopefully better diagram.
Thanks for the feedback!

Pilgrimman wrote:Either I didn't explain well (Probably) or I drew a crappy diagram (also probable). I've built two working piston guns, so I understand the principles of pistons.

Instead of the pilot creating a pressure difference that allows the piston to get pushed back , the solenoid "pulls" the piston back, against the force exerted by the spring. (I am probably erroneous in calling the pipe a piston in this case, but bear with me)

It seems from your post that you thought that this idea is intended to pilot a sprinkler valve. It is not a pilot. No air is wasted. The sealing face (red) is against the barrel (kept there by a slight force due to the compression of the spring). When the "piston" is "pulled" back towards the bumper (orange) by the solenoid, (the spring with a current flowing through it (purple)), the "piston" no longer seals the barrel.
If this is still confusing, I'll work on another, hopefully better diagram.
Thanks for the feedback!

Yeah, sorry about that, I realised that I wasn't thinking outside of the box and changed my post as quickly as possible after I realised what I was looking at.

It would work, but I don't think you fully appreciate the forces involved. In order to fire a 4.5mm BB launcher at 100 psi, the solenoid would have to exert a force of aroud 2.5 lbs, which is fairly reasonable. For a say 3/4" launcher at the same pressure, that solenoid needs a force of almost 45 lbs to open the valve - so unless you have ridiculously huge solenoids, it's only practical for small calibre launchers at relatively low pressures.

You can however use the solenoid to accelerate a hammer that knocks the valve open through momentum, as opposed to using it directly.

I was hoping to use it for small stuff. If I want to shoot 3/4" stuff, I'll just stick with my (air) piston gun! I was hoping to build a gun to break the sound barrier using reasonable pressures, but it'll probably never happen. Thanks for the input!

Pilgrimman wrote:I was hoping to build a gun to break the sound barrier using reasonable pressures

That would need high pressure in the 400 psi+ region, as well as a super efficient valve like a burst disk. I think this system would be more suitable for someone trying to make a small calibre automatic.

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