Note: I have been very busy with work as of late so I am not likely to upload any design files (CAD, etc.) or instructions any time soon. However if you are interested in duplicating this design, please reach out to me. It might be just the motivator I need to go back through all my old files and dig the drawings out!
The basic mechanism is simply a servo-driven cam that sequentially "crimps" soft latex tubes as it passes them in its circular path. The water never leaves the tubes, so in a way similar to a peristaltic pump, the system is unlikely to leak, and could even be used in food-safe applications.
The first (non-functional) version was 3D printed, but I decided to use laser cut parts instead because I felt that more people would be able to inexpensively duplicate the design. Acrylic was the most cost-effective choice, however future iterations will be made from delrin, a strong plastic with a very low friction coefficient.
This model is of a "normally-closed" design, meaning that at any time, either exactly zero or one of the eight ports is open to allow fluid flow.
The first functional prototype works pretty well, but there is room for improvement. As pressurized water flows in, the cam within the main disk rotates, opening one port at a time. This version was able to restrict 100% of the flow at pressures of up to 80 PSI. I believe that with further optimization, a smaller servo motor could be used, which would reduce the total weight.
Please see the video below for a nice illustration on how this works. The valve in the video is the actual CAD model. It is made with three distinct plates, enabling the design to be easily manufactured on a laser cutter, router, or even a drill press and file.
This is a simple motion test of my 1 -to-8 crimping valve design. Observe the rotating cam making sequential contact with the 8 crimping beads. These beads compress the latex tube to stop flow.
This project has been shelved for awhile, but I hope to start working on it again soon. Stay tuned!