Using collaboration for Open Source Stirling Engine
The Big Idea
Using software approaches to a mechanical design including open source collaboration and modular design, to create a low-cost Stirling heat engine. See my project page at:
The solutions to many of our green energy challenge will require mechanical solutions as well as software and information technology. While many large software projects are using open source collaboration, the mechanical world has few examples.
It is be coming obvious that there has to a more modular approach to mechanical systems. One that would allow greater reuse by allowing upgrading of system components rather then disposing of the entire product and replacing with one that is more efficient. This can apply to may of the current products, solar energy systems for houses and hybrid vehicles. Where components could be swapped out as better ones become available.
The project I chose was a Stirling engine design, it is much smaller and can be built using simple tools found in any small shop.
The goals is to have the engine be very low cost with standard components, like piston, cylinder, head, case, cam/crank shaft, heat exchange and heat regenerator components. So as the technology improves, the old parts could replaced with better ones without having to buy a whole new engine. It also allows independent development of the components without having to worry about building the entire design. Please see my Open Stirling engine project website and blog at http://sites.google.com/site/openstirlingengine/Home and http://openstirlingengine.blogspot.com/
The first project is an demonstration Alpha cycle engine that is parametrize able.
It can have as little as 2 cylinders, preferably a multiple of 4. Each pair of cylinders actually creates an independent thermal engine, so one pair has a problem the others will still be able to run.
The primary problem with Stirling engines is maintain a good seal. They have more pressure the higher the pressure of the working gas.
The biggest innovation in this design is the use of a thin film material in the form of bag to create a complete seal between the piston and cylinder. Since the actual piston and cylinder surfaces are not in contact, they can have loose tolerances and surfaces that are not perfectly smooth. My hope is use standard pipe and/or tube materials for these components.
Another design goal is keep the number of part types as low as possible and reuse them as much as possible. For example the case is made from 2 basic parts, ends and side pieces. The length of the sides is determined by the number of cylinders and extended as needed.
I am very close to completing the 4 cylinder clear plastic prototype, but am having problems maintaining the seals. I have trouble finding sample bags other then polyethylene. They are too fragile, I need a tougher material and have not had much help from plastic suppliers to get Nylon or other materials.
Please see my Open Stirling engine project website and blog at http://sites.google.com/site/openstirlingengine/Home and http://openstirlingengine.blogspot.com/
There I have drawing and pictures of the current prototype.