Hi,
The design intent is to be able to generate DC power to charge a battery in remote areas I visit where my solar panels are shaded. I have a wood fired boiler design in mind, but won't build it until I am satisfied that the current engine will generate sufficient power using compressed air.
I learned a bit more.
It runs very smoothly now since I attached a machined 5Kg gym weight as a flywheel and re-timed the slide valve back to around 14° angle of advance. This is more in line with the Bilgram diagram I drew up. I had it set by eye to around 27°, far too advanced.
I can get it to run down to 60rpm smoothly and 50rpm with a bit of variation in speed as the flywheel effect takes over at the end of strokes.
I now know that I can generate approx 4A into a 12V system. I hooked up a car alternator to the 130mm drive pulley (I had to make a new 45mm pulley for the alternator to get enough speed). Problem was that all of the energy being generated was being used to excite the field windings in the alternator and not enough speed to get some output for the charging system.
The plan is now to make a permanent magnet alternator which will substitute for the flywheel. Solidworks tells me that the mass of the alternator flywheel is roughly the same as the current flywheel (4.5Kg). I am going to use an axial flux design approach. I have the design done in Solidworks but have had a devil of a time trying to find a steel supply place to cut me 2 pieces of 5mm plate 216mm square. After approaching no less than 4 suppliers I finally found someone who actually got back to me with the plates.
The intention is to make the 216mm square plates into 215mm round plates with mount holes for the magnets and hub. The hub will attach directly to the 12mm engine shaft by means of a 4° taperlock that I make myself, the same arrangement I currently use for the gym weight flywheel.
When I get the plates machined, I'll order the magnets from China.
I'll keep you posted with further progress.
Regards
Chrisjh