Custom

[russc]

Originally Posted by y0da900

http://haveblue.org/tech/patents/US006343599.pdf

That's a patent for a pulse valve issued quite a while ago, it states that it is a Clippard PV-1 with alterations made to the restricted orifice to reduce the pulse length, but ~8ms is claimed in the patent.

I've got another method for a mechanical valve that I'll put in another thread.

That patent's inventor is Aldo Perrone! Maybe we'll see a pulse valve Stinkray?

Hey, I just had a thought. We can accurately call this Cheytac A-5 a Pulse rifle!

[AirH0g]

Y0da900, that's a good find right there, wish i would have seen that before i started in on this. I would have went a different way in regard to moding the PV-1. Probably saved some time too

Al Ray, I would love to see some pics of those old PV's The body of these new ones are built extremely well, and will easily hold the pressure, it's the cheesy internals that have the difficulty with it.

The stock PV-1's are suppose to give a 100ms pulse, although at 0 volume,they will pulse at 42ms. Instead of trying to get that lower and start having to guess what it was at, i went with that number (42ms) and adjusted everything around it. The added volume chamber, lower pressure (200psi), and barrel length (all 18 inches are used) were all calculated around it.

The end result was pretty faithful to the calculations, although the CVX valve was a bit of an unknown after doing all the modifications to it, so all in all i would have to say it's definitely not perfect, but it works very well on the cheytac. Although i'm sure it could be executed better with more accurate calculations.

[y0da900]

I'm honestly not sure how much use it would have been to you if you had used it as "directions" for the modification. The written description in the patent seems to contradict the schematic diagram, it has the flow of the check valve described differently, and making the orifice smaller seems like it would have the opposite effect of what they are claiming.

If you want a system with the dwell time adjustable, feel free to try the system that I posted the other day or some variation on it, with your obvious talent I'm sure you could make one rather handily.
Mechanical MQ like valve design

[AirH0g]

Yes, when looking over the patent, i started to realize that it's not much help at all. In fact if i had to do it over I would most likely make my own PV. with an adjustable dwell as you describe in your other post.

I had thoughts of modifying this one with a similar adjustable volume chamber for the PV to control dwell, but in the interest of keeping it simple for the customer i decided against it. It would have been real useful at the end though when i was tuning it all.

[Titus]

First time seeing that site and I'm very impressed so far.

[Grivooga]

I've got to get to work so no time to read all the replies... but, wow, that's custom. Honestly I don't even see the point of starting with the A5 as opposed to a complete custom build by the time you get to that point.

[big jim]

Originally Posted by AirH0g

The stock PV-1's are suppose to give a 100ms pulse, although at 0 volume,they will pulse at 42ms. Instead of trying to get that lower and start having to guess what it was at, i went with that number (42ms) and adjusted everything around it. The added volume chamber, lower pressure (200psi), and barrel length (all 18 inches are used) were all calculated around it.

The end result was pretty faithful to the calculations, although the CVX valve was a bit of an unknown after doing all the modifications to it, so all in all i would have to say it's definitely not perfect, but it works very well on the cheytac. Although i'm sure it could be executed better with more accurate calculations.

AirHOg,
As a relatively new engineer ( I deal with solids normally, not these magical gases I can't see) I am curious about how you calculate this. I assume Bernoulli is involved but there must be much more to look at as well. Is there somewhere I can go to learn more about pneumatic valves and the calculations involved?

Thanks.