Hi all,
I have mentioned in a couple of posts that I am working on a design for a simple stirling engine.
I have looked at many stirling engines on the internet over the past couple of years but am just really getting back into model engineering.
In the past I've only made oscillating (wobbler) steam engines so I wanted to keep the design simple for my first stirling engine as I am aware that certain fits need to be much better than for steam engines if the engine is to work.
I have done some 3D modelling on a free downloaded version of Alibre design which is very good. The main problem is that it only lets you have a few components in an assembly, then it disables the save function! So I had to assemble my engine, take screen dumps then just quit and watch the assembly work go down the drain! I just assembled all the components to make sure they fit together ok and the engine looks ok. I am quite happy with the outcome, I have put a few cosmetic features in there to make the engine look a bit nicer which could have been left out to make it more simple. I figured I might as well make it look nice so that it's something worth looking at rather than a bodged engine that works.
Anyway, enough of that, I attach a few views of the assembled engine. I have left bolts and pins out because basically I could be bothered to model them!
I still have to create the working drawings for all the parts yet but that is fairly easy now the 3D models are there.
A bit about the engine:
The flywheel is steel as is the crankshaft. The crankshaft is a 1 piece design however I may make this up of three components, shaft, disc and pin. Depends what I feel like, I want to try one from solid.
This will run on ball bearings in the aluminium pedestal. The con rods are aluminium but will also have ball races in their big ends. The small ends will have silver steel pins through bearing in the brass of the power piston and displacer small end bush.
The power cylinder and piston are brass (I know there are better materials but this should work as long as the fit and surface finish is good.)
The displacer cylinder is finned aluminium (i know the fins could be deeper and more of them but I want to keep this simple, this may limit the running time of the engine as not efficient cooling).
The hot end of the displacer cylinder will be stainless steel if I can get hold of some.
The displacer itself is aluminium and it's rod will probably be bronze brazing rod or steel.
The power cylinder has a bore of 10mm and a stroke of 10mm. The displacer is 14mm diameter and is run from the same crank as the power piston with 90 phase angle.
The ratio of swept volumes is therefore 2.0. I designed it to this slightly high figure as the temperature differential won't be that large in this engine, I want to try to run it from a tea light. (one of those flat little candles)
If you could all let me know what you think I and if you can see any glaring errors that would cause the engine not to run I would be grateful.
All I am after is an engine that will spin over happily for a while as it's my first attempt!
Thanks,
Nick