View Full Version : IP to get things rolling - mechanical MQ

07-01-2008, 06:32 PM
Iíve been working on this one for a while, but I donít have time to build it right now and probably wonít for a while, so Iím hoping someone here might want to give it a try. Itís my take on a mechanical MQ like valve. It has no hammer, and operates on differential pressure and biasing much like an MQ does. Criticize it, build it, make a fortune off of it, do whatever.

Instead of venting the gas to atmosphere to create the differential, this opens the volume behind the shuttling part of the valve to a larger chamber which creates a near instantaneous volumization and subsequent loss of pressure/altering of the valves bias. Instead of a bleed hole through the valve, there is a line tapped from the main chamber that goes through a FCV (flow control valve) to the chamber behind the valve.

At steady state rest, the valve is biased forward and closed. When actuated, the piston moves rearward, creating a pressure differential (due to the increased volume without a simultaneous re-pressurization) that allows the valve to open. Air will continue to flow through the FCV to re-pressurize the now volumized chamber. When a set pressure is reached (determined geometrically with the valve and with the main chamber pressure), the valve is biased forward and closes. The piston can now move forward (via releasing the trigger and moving the flow from its valve), sealing the chamber to its original volume, and venting the volumization chamber. Altering the flow through the FCV and the volume available to the volumization chamber should result in the ability to alter the duration the valve is opened (mechanical dwell).

One could eliminate the FCV and use a hole through the valve just like an MQ and adjust dwell via volume alone, but at least experimentally, this is one more degree of freedom and resultant adjustability. Correspondingly, one could have a set size volumization chamber and alter strictly the flow. Probably a much smaller design once a good average volume is determined.

Used on a smaller scale, the valve could be used to actuate a 4-way or 5-way valve instead of as a main firing valve, allowing purely mechanical control of just about any gun that relies on electronically controllable dwell.

With an extension on the front of the shuttling portion (and no vent through the body), it could be used as the firing valve in a blow forward design, or a closed bolt spool. Much like one of Pneumaggerís designs for his senior project that he posted, and PBJoshes Shiva, but without isolating the firing chamber from the air source and with an unbalanced valve. Thatís assuming mine would work at all.

A patent exists for guns fired with a pneumatic pulse valve, patent number 6,343,599, but operates in a very different way than this. That version requires you to switch via the trigger the same gas that is being pulsed, meaning that if you require a 150psi pulse to operate your gun at, you need 150 psi at the trigger valve. Mine allows differing pressures at the trigger valve and of the pulsed air. It is also based on modifications done to a standard Clippard pulse valve to shorten the pulse, as they are ~100ms out of the box (<10 cycles/second). It is unlikely that it would have enough flow to be useful as a main firing valve as well; that would be quite an impressive flow through the trigger valve.

The current drawing is not optimized for flow or performance, but to try and better match the limits of my lathe. The piston will balance itself during the firing cycle allowing lower trigger valve pressure. The volumization chamber has very little volume change once the seal between the 2 chambers opens.


This is an older inferior variation (just for conceptual purposes). The piston has a rather large rearward bias when actuated, and would probably need to have much higher pressure at the trigger valve than the other variation. The cyan and yellow portions on the right hand side move, altering how much the piston can move and subsequently how large the volumization chamber becomes, it increases in volume as the piston moves.