Piston Valve Hybrid
Posted: Sun Aug 26, 2012 2:00 am
Hey all,
It's been a while since my last post, but I'm still bent on building my piston valve hybrid so I'm looking for some advice or tips on how I can improve the design.
The picture is pretty basic but it is to scale and should show the basics of how it works.
Firstly the arrows indicate non-return valves or check valves. The idea works basically like a co-axial piston valve pneumatic, except I wanted the two chambers completely separate so as to not let the fuel seep into the rear chamber and igniting, which means there would be little or no pressure drop in the rear chamber and the gun simply wouldn't work. So I introduced check valves to have equal pressure in each chamber, but with the rear just air/oxygen, and the primary the fuel mix.
The ignition points have't been drawn but they are in the primary chamber.
To ready the gun, the air line is opened but with the primary chamber air line valve turned off. This increases the pressure in the rear chamber only so the primary chamber can be pressurised with fuel without the rear opening. Next, the fuel line is opened and the primary chamber is pressurised to a specified pressure before the primary chambers air line is also opened. All lines are then closed.
As the piston valve has a greater surface area than the primary chamber's barrel seal and other side of the piston, it will hold closed until the primary chamber is ignited and the total surface pressure on those seals in the primary chamber go above that of the rear chamber. I've done some maths on the surface area of these seals to make sure it opens at the right pressure to maximise performance.
The black in the rear chamber indicates a rubber stopper to absorb the impact of the piston on ignition.
After ignition, the air lines are opened and closed to vent the chamber and the piston rod is then manually pushed back to form a seal.
I am wondering though if there is anyway I can make it more autonomous or simplify anything. Any advice is welcome.
Cheers,
Jacob
It's been a while since my last post, but I'm still bent on building my piston valve hybrid so I'm looking for some advice or tips on how I can improve the design.
The picture is pretty basic but it is to scale and should show the basics of how it works.
Firstly the arrows indicate non-return valves or check valves. The idea works basically like a co-axial piston valve pneumatic, except I wanted the two chambers completely separate so as to not let the fuel seep into the rear chamber and igniting, which means there would be little or no pressure drop in the rear chamber and the gun simply wouldn't work. So I introduced check valves to have equal pressure in each chamber, but with the rear just air/oxygen, and the primary the fuel mix.
The ignition points have't been drawn but they are in the primary chamber.
To ready the gun, the air line is opened but with the primary chamber air line valve turned off. This increases the pressure in the rear chamber only so the primary chamber can be pressurised with fuel without the rear opening. Next, the fuel line is opened and the primary chamber is pressurised to a specified pressure before the primary chambers air line is also opened. All lines are then closed.
As the piston valve has a greater surface area than the primary chamber's barrel seal and other side of the piston, it will hold closed until the primary chamber is ignited and the total surface pressure on those seals in the primary chamber go above that of the rear chamber. I've done some maths on the surface area of these seals to make sure it opens at the right pressure to maximise performance.
The black in the rear chamber indicates a rubber stopper to absorb the impact of the piston on ignition.
After ignition, the air lines are opened and closed to vent the chamber and the piston rod is then manually pushed back to form a seal.
I am wondering though if there is anyway I can make it more autonomous or simplify anything. Any advice is welcome.
Cheers,
Jacob