Intank regulator project…
Hello Guys,
I thought I publish my project so far. I have been designing new regulator which will go inside main tank. The reasons are simple;
-it won’t take space between gun and tank
-it’s safe since everything is inside tank
-the big forces are all gone and replaced from stretching to compress
-there is good space for relatively big size regulator chamber which is needed (25ccm) for low pressure and wider pressure-range (more usable shots)
-the firing valve is separated from regulator design so one could use any valve available (although it needs connection thread for regchamber)
I already built two prototypes and tested them on dedicated testbench. The regulation works. I did few hundred of strokes and it regulates the pressure everytime to set value. I still need to examine different poppet-valve sealing materials since I am not 100% happy with current implementation. Over few hour period there is some pressure grawling noticeable meaning that first shot will be little faster than rest.
The difficulty for Talon regulator is the filling. It has to be able to handle bigger forces during filling and also has to pass trhough the air from regchamber to the tank. That was the reason for “inventing” poppet-valve to the regulator. It handles both. Eliminates the bigger forces against regulator-sealing and acts as oneway-valve during filling.
The regulator is designed for 300bar and the regulator body can handle 3x that pressure when it comes to strength.
When used with 100bar pressurerange the accuracy from first to last shot is about 1.6% leading to 1.2m/s velocity drop over whole range. Of course there is little bigger variation during string because of other factors.
This is how it should be assembled to the gun….
The princible of regulator…..
-spring lifts poppet-valve’s stem and air starts to flow from tank over valvestem to the regulator chamber
-pressure in regchamber raises and exceeds springdiscs force and regulator pistons moves to the right. Poppetvalve closes.
-shoot and the cycle restarts
-during refill the overpressure in regulator chamber (against tank) will push the poppet-valve open and air will flow to tank
-the regulation pressure is adjusted with big M14x0.5 thread in the “tophat”
-do realise that the flowchannel in poppetvalve is 10x smaller than through the regulator piston. The pressure is always same one bothsides of piston’s heads. So don’t get confused about the “reverse” design.
The parts….
Prototype number two…
Poppet-valve and integerated sealing…
About the scale of parts….
Bench testing….
In the bench the regulator is inside aluminium tube…
It’s not ready yet but it’s a step closer to our common goal… regulated Talon which can shoot consistent shots with wider pressure-range and wider ME range. Next I need to build or get main firingvalve to be able to perform some fieldtests with gun.
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Yeah, where is Mike? I know he was working on a new project. It would be great to hear from you again. I hope all is well.
McMike…
Anymore progress on this?
Thanks 🙂
I would buy one if it’s reliable and still easy to fill the tank with a pump.
hi guys, wow, you guys are always and really going ahead of airforce itself! Nice one! Did anybody here in the states build a reg. already??
mcMike, there is a saying “analysis paralysis” that frequently happens to engineers. Sometimes, you just have to adopt the Nike motto i.e. “Just Do It”. I wish I had the mechanical abilities of you guys but like someone else had mentioned, handling a screw driver is pretty much my limit. All I can say is members like you make me glad that I have bought a Condor. I look forward to seeing your in-tank regulator in action some days. All the best !
Doh, sorry Mike, Ive already got most of my redraw finished already. I will work it out again like you suggest after I get this pic up. I would rather get some feedback before I spend the time on that anyway. I should be able to finish it when I get home from work tonight.
When you start drawing try to do it this time like I suggested 🙂
First go to http://www.industrial-springs.com/default.asp?id=529
You can choose the correct disc-springs. The dimensions are metric but it’s a nobrainer to make conversion. Basicly there are two sizes that looks promising. 10/5 (0.39″ / 0.19″) and 12/6 (0.47″ / 0.24″) . Where bigger diameter is the outside diameter in mm and smaller is the diameter of hole through it. Check the thickness, free length , Force and travel. You stack the discs and get different results.
If you mirror them you get double the stroke /\
If you use same side you get double the force \\
And you can combine it // \\ // \\ for double the force and quadruble the stroke.
So after that you get diameters for the piston. (flange OD and axle OD). Which will set limits to bore through piston and other things.
The max diameter you can use is 16.2mm (0.637″). That is the ID of bottle thread (M18x1.5) and everything needs to fit inside if you go to the tank.
To calculate the forces:
Force = pressure x area
If you use metric dimensions it’s easier since you can move from Pascal to Newton very easily. Here’s shortcut for calculating with bars.
For example 12mm diameter in regulator piston.
P=regulated pressure (say 100bar)
A=12mm -> 6^2*3.14 = 113mm2
F = 100 x 113 / 10 => 1130N
If the otherside of piston is 6mm the force is:
F= (3^2*3.14) * (100) / 10 => 196N
Total force is 1130-196 = 935N
So you need the spring configuration that produces 935N at 100bar or actually little more for reserve. Check from the page and you see that 12mm springnum (01202200) has force for 547N. So if we stack two of them ( \\ ) we have enaugh force.
Also we need some spare for stroke since for one spring it’s only 0.26mm. That means that with 0bar to 100bar it will only move 0.26mm which is too little. Even 1/100 mm movement will change pressure drastically so we put 4-6 of them in the row and have total of 12 springs in configuration:
12 34….
\\ // \\ // \\ //
Now you can draw the springpack. OD=12mm, ID=6.2mm, length=9.3mm free and compressed 9.3-(6*0.26) = 7.76mm.
That is a foundation you can work and start drawing things around it. Even with photoshop you can do things in scale if you enable the grid. Just set the grid for mm.
Next you need the O-rings. The thicker the O-ring is the better it seals but more friction it has during movement. In the regulator all the movements are so small that they can be calculated as static.
Very likely you can find almost any inner diameter for O-ring but the thickness is limited. They are basicly 1, 1.6, 1.78, 2, 2.4mm in this scale. So when you draw the O-ring (and O-ring slot) use those numbers as guide for thickness (the diameter of torus-ring).
If you try to do it like I suggest you can see at very early stage yourself is the design possible to do. There is no point drawing O-ring with 0.2mm thickness since it’s very likely won’t exists and even then it won’t be strong enaugh in this application and lastly the permeability is so big that air will penetrate the material.
I was able to copy my PhotoShop from another of my PCs so I will get it redrawn very soon. I wasnt able to find my original disc though, that kinda bugs me. Oh well.
Being able to adjust the regulator under load is also a concern for me. I think it will be doable but you will have to look at it for me and let me know. Even if you had to drain the tank first and then adjust it still has some benefits because the spring chamber is vented to the outside air.
I really liked the idea of passing the regulator through the tank but everyone told me that modding the tank would be the worst thing I could do. Because you are pulling the two ends of the tank towards each other I would think it would be just as strong if not stronger and would make the regulator much simpler. I abandoned that idea after all the warnings though.
I look forward to your help and ideas.
Thanks.
Yes that is one option. It’s the method I use to drain the tank and works very nicely. First I tought it will take long time and you need to be extra carefull and bleed slowly but it’s quite fast. I have needed to drain the tank so many times already that I have gotten used to it. I do it in one run without pauses. The regulator chamber is VERY cold after that as supposed 🙂
At this point I am just testing it and see how many shots there is before the regulator settles. I will perform few tests with couple of different smaller sized chamber as soon as I can to get more knowledge. IF the chamber can be smaller it will be helpful news for original-concept to put chamber outside.
I also thought about dump-valve in the side of mainvalvebody to bleed excess air out.
btw, Why don’t you try to redraw and present the idea about your new regulator idea? The version which can be adjusted outside.
I will help you out if it’s doable concept. I propably know what kind of design you mean since I also played with several methods to make regulator adjustable on-the-field. I am just afraid it’s not possible. The forces are just so big that you can’t turn the spring-setting screw while it’s under load. We all know how much more difficult it is to even adjust powerwheel while it’s loaded- and regulator has 10-100x stronger forces.
I rechecked your pictures and saw that you also thought the idea to move regulator outside trhough the tank. I also planned this at one point very seriously and I still think it’s possible. It would even make the main tank more stronger if done properly. It would solve the springchamber venting and maybe make it possible to adjust regulator on-the-fly. It would need very big handwheel for that. At least 50-60mm diameter. But better gain is that you could put couple of gauges in the back too. One for tank pressure and another for regulator.
On the problem with full pressure in your regulated chamber after a fresh fill. You could fill your tank as normal. After filling you could put a nut in the fill adapter or spacer that will open the valve when you screw the adapter onto your tank. When you screw this on it will pressurize the hose between your tank and pump, or scuba tank. The gauge on your fill adapter should show the pressure thats in your regulated chamber. Now just open your bleed valve a tiny bit to bleed off the overfill in the regulated chamber. Close the bleed valve and remove the fill adapter.
If the spacer in your adapter is the right thickness you should be able to unscrew it without draining to much pressure out of your tank.
That’s an interesting idea.
I think I will make the tophat flange OD just little bigger (~20 mm) and use Al breech which is carefully machined to mate the two surfaces. Also check if I can tighten the hammer-OD tolerances against body.
Shadoh, I am still sorry you feel that way. My intention is not to dismiss them but honestly to push you forward with actual design since you do have good ideas. And I meant what I said. Ideas are always good and without them it’s impossible to proceed but I like to quote Einstein’s famous words; It takes 1% for an idea and 99% hard work to make science. This is not science but the same princible applies. I can see that in my dayjob even in daily basis. In brainstorming meetings there are tons of ideas but actually very few of them are doable in the real world. And I see exactly the situation you mentioned about engineers dismissing ideas. It’s just because usually the people who have to do the 99% of work knows in advance which is not possible. They can take a look of sketch and tell you without further study that the forces, manufacturing, etc. is just not possible in that scale or for some other valid reason. I hope I don’t sound harsh again but if you would start with real stuff (real springs and sizes, real minimum wall thickness, etc.) and start building the idea around them then you would have solid foundation which could be actually doable. You can do that what ever tools you have available. Even with millimeter paper.
This is the way I work myself. I calculate the involved forces and pressures. Then look if there is springs to handle that force and draw them. Then I draw the idea around it and work my way up from there towards the concept. Push things around in other order and see how they can be fit inside. If I see that I can change size of piston I recalculate forces and look for new springs. etc.
I see your point about secondary piston but for me that was not the starting point. It was the ending point. The reason for second piston was not filling but handling too big load to primary piston during refill. The poppet-valve did exactly that but it had a flaw in design which prevented good sealing to happen. The other solution would’ve been adding second spring to the piston which is not possible because of scale and available space. At one stage there was a ball check valve inside secondary piston for refill. DFM (design for manufacturing) process lead to a solution where that could be eliminated with different design in secondary piston and make it do the work of one-way valve too.
Internal a.k.a. Intank-regulator is actually an old idea used for ages in industrial devices. The main reason to go inside was safety. I have concerns about 200+ bar pressures especially making parts myself and using them next to my eye. Moving it inside makes things safer. Making 20ccm chamber between gun and tank needs only about 2 inches extra for neck-length and is not difficult at all. It will be little heavy though. The bonus with going inside is lesser forces and switching from pull to push which is easier to handle. It was the evolution during design process which lead the move to inside – not the initial concept. I have a design with stronger (7000-series) aluminium for regulator body and without intank chamber which would be much lighter. Now that I have made protos and tested them and know more about strenghts I might go next for model that fits between gun and tank. Maybe try inline-regulator too since that would simplify many manufacturing issues.
What I meant about your work inspiring me was that I appreaciate your ideas and talk about regulators. When others said it’s not possible you came with a new idea showing different ways and never losting your belief. So I knew there are some other people having faith that it is possible and it kept me going. So Thank you for that.
If I could have or could purchase regulator for Talon from shelf I would be more than happy. And nothing would make me happier than have some quality valvemaker to start producing retrofit regulators. The more they make the more it will evolve and better it gets. Maybe I could ask little discount if they used exactly same design and final drawings. Even if they make good profits with it I wouldn’t mind since I had that opportunity also but didn’t take it. And I still wouldn’t take it since I know that even after few hundred hours work there is at least 10x more to do before it could be mass produced.
And if AF would use my design in their regulators I would be quite honored knowing myself that I have done something propably right.
Why don’t you try having the breech and tophat magnetic?
I think it was THX1138 on TOG who actually did this. Not sure of tophat material but he embedded magnets in the butt end of the breech. Should offer a pretty reliable/repeatable mating of the two parts (kinky 😉 ).
Ive experienced this myself. Ive considered putting the tiniest groove on my tophat for the Oring in the breech to slip into when its fully closed.
Marc,
I do in fact have just such an idea and will be posting it as soon as I can get it redrawn. I lost that and all my other “artwork” as well as everything else I had on my last hard drive. I really gotta start backing things up. My copy of PhotoShop was on that drive as well and I cant find all my discs for it. I think my kids “loaned” them out to some of their friends.
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Hi Mike
Can I ask you a question on behalf of an engineering friend of mine? After I told him about your project (beautifully illustrated by the way) he asked me to enquire about the liquid plastic you use, could you give me any information about it please?
Steve Topp