I have a NEW idea for a valve

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jambs08

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Mar 7, 2016
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As a hobby, I've been working on valve designs for airguns, and I wanted to get some feedback on it. My idea is very similar to a striker activated blow open valve (a rough drawing of a blow open striker valve that I found online can be seen here.)
https://imgur.com/5tIMEwr

The striker is the C-shaped component, and whit it is set it pushes the valve closed. The valve has a slightly larger diameter than the rod, so the air pressure helps keep the valve shut. To open it, the striker is released, The striker hits the collar at the end of the piston, and that forces the valve to open. Once the valve is opened, the air pressure assists the valve to open further. 

My idea is to eliminate the striker by making the rod with a slightly larger diameter than the valve. I have a very rough drawing of my idea here.
https://imgur.com/YSKEoLY

The cylinder that seals the valve by nesting in the exhaust port (1) has a smaller radius (small) than the cylinder (large) that is nested in the return guide (3). The pressure below the piston inside the return guide could be adjusted to help control the opening and closing of the valve. When the piston is closed, the net force attempting to open the valve is small because it is equal to the pressure multiplied by 3.14(r large^2 - r small^2). The fluid in the container (4) can not escape through the exhaust port (1) or the return guide (3) by adjusting the ratios between the large piston and the small piston, you can control how much net force is acting on the piston prior to opening it. Since the force acting on the valve can be controlled, a mechanical lock or a solenoid could keep the piston closed even at extremely high pressures.

Once the piston is release, the gas will be able to flow through the exhaust port (11). the force acting to open the valve will also increase because the area that the pressure acts on will change from 3.14 (r large^2 - r small^2) to 3.14 (r large ^2). This increase in force will allow the piston (12) to open rapidly and remain open until the pressure has dropped. The piston can be pressed down against an elastic force that will return the piston to the closed position once the pressure inside the gun has dropped. Here's another rough drawing.
https://imgur.com/UvfJVkH


I believe there are three advantages to this design compared to a striker activated blow open valve. The first advantage is it requires fewer pieces. My idea still has the valve, the piston, and it requires a locking mechanism to keep the valve shut when there is a high air pressure, but it does not need the striker or the collar. The second advantage is this should be more compact since it eliminates the need for a striker. the final advantage is that once the pressure has dropped, the valve will return to the closed position.

Thank you so much for taking the time to look at my idea.

JA

MOD EDIT: EMBEDDED PICTURES
 
Well, I wasn't going to reply, but you asked (yes, I'm an engineer, or at least I play one at work, and design valves and regulators for a living).

Trying to follow the sketches and description...it sounds like once opened, this valve will not shut until the pressure in the space 14 is vented to near zero, or at least some pressure low enough for a return spring to act against the pressure (I'm assuming, perhaps wrongly, that the pressure at 13, back face of the piston, is just atmospheric pressure?). Thus, the valve will open more and longer when the pressure in 14 is high, and will open less and for shorter times when the pressure in 14 is low. This is the opposite action from the typical bash-valve used in multi-shot PCPs. I.e., you would get very high impulse delivered to the pellet on the first shot, and then progressively less impulse with each subsequent shot. If the operation is reversed, like the typical bash valve, you would get small amounts of high pressure gas, and progressively longer opening times as the pressure decreases, for a somewhat flat impulse vs. shot curve (how flat, and over what pressure range is the issue that designers and tuners wrestle with).
 
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Thanks for the response, you are exactly the type of person I was hoping would comment. You are correct, once the valve is open it won't shut until the pressure is almost zero. I can think of two set ups that might work well with this. The first is a single shot where all the pressure is released. The second situtation would have two air reservoir. The large reservoir would refill the small reservoir, which would power the individual shots. You would need a a valve to separate the reservoirs with a valve, but this valve wouldn't need to open and close rapidly, so a ball valve should work great here.

If you were to put a regulator in between the reservoirs, and operate the smaller reservoir at a lower pressure, you could actually have identical air pressure for several shots in a row. I'm hoping to build one over the summer, and I'm planning to use a paint ball HPA tank for the large reservoir, and schedule 40 iron pipe for the small reservoir. The HPA tank can store air at 3000 psi, but due to the regulator built into it, the smaller reservoir will only be filled at 800 psi. I know I'm sacrificing a lot of power doing this, but the materials I can get my hands on are all rated for less than 1000 psi, so I can't safely shoot at a higher pressure anyways.

If you have any additional thoughts or suggestions please share them.
 
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"additional thoughts or suggestions"

Use better material ! A tube rated for pressure doesn't cost all that much ( grab a discovery tube maybe then just be VERY aware of what any mods, drilling/cutting/heat may have on said tubing). Iron is very scary and "I" wouldn't want 100psi inside a section. 
Do have fun learning and building, just be safe, it's worth an extra $20.00 or so.


You might look at drwaings of the sportsmatch GC2 which used two sections , one for high psi one for the regulated section with a manual fill button and basically a dump valve..


John
 
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"jambs08"If you were to put a regulator in between the reservoirs, and operate the smaller reservoir at a lower pressure, you could actually have identical air pressure for several shots in a row.
Click to expand...
I had a similar idea. It seems like you could get a very good consistency and shot count if the secondary reservoir could not start refilling while the main valve is still open. Let us know if you try it!
 
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Here is a link to getting various metal products. http://www.onlinemetals.com/?gclid=Cj0KEQjw5ti3BRD89aDFnb3SxPcBEiQAssnp0lh-uo-fesA_GPWpD1Ar3V_t5NHHTh6Q6hyrLaa1xCYaAm5G8P8HAQ

I'd suggest looking at DOM steel tubing. You can get this stuff in short lengths and with a mill report. The mill report will give you the tensile strengths of the actual batch of steel (heat) that the tubing was made from.

Also, research hoop stress, shear stress, and safety factors to figure out how thick of a wall you need for the pressures you desire. Also make sure you have an adequate design for your endcap retaining methods. Screw threads tend to be stronger, but you need a lathe to get the threads square with the tubing and plug/end cap. Also, if you go with threading, a radius in the thread relief (where the threads end) will make for a stronger tube. 

The other method of retaining caps and valves inside tubes is with screws or pins. These fasteners will be in shear, so you need to calculate sufficient sizes and account for the compressive strength of the tubing; while the fastener may have enough shear strength, the hole in the tubing wall may deform under the load.
 
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Thanks for bringing this up. I tried to illustrate one in my description, but your picture is better than the one I had. The balanced valve that you showed is very similar to the one that was in my Tippman 98 paintball gun. The ones I've seen always have a larger diameter at A1 than A3, so the pressure helps the valve stay close, and the only way to open it is to hit A2 with some thing. What I want to do is to make A1 smaller than the diameter at A3. This will push the valve open if there isn't a locking mechanism. My thought process is that the valve will be be more effective than a knock open valve because the rod (A2) won't be needed, so the port opening will be larger. I also think it will be simpler to make and more compact since it won't require a striker to open the valve.

Do you know if they have they already made balanced valves like this? Thank you so much for providing me with feed back. I appreciate it.

 
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