Gallery

Bo Englund, Beijing, China bosse@kaxy.com bo.englund@yahoo.se 3/8/2008

MY FIRST HOT AIR ENGINE

Everything started when I found some free drawings for this engine at http://boydhouse.com/stirling/ The drawing is with all measurements in inch, I have to change to mm to be able to work in a good way. I also changed some in the construction, and for some parts. But in general I followed the drawings.

I started to do the engine foundation. It’s made from 10 mm thick aluminum.

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The two parts are jointed with 2 x 5 mm screws. Later I will replace them with 5 mm hexagon screws. There is also one threaded M5 hole in the bottom of each piece for assembling to the bottom plate.
L: 68,4 mm
W: 41,9 mm
H. 71,5 mm. (highest)

The next step is to do the main axel, belt pulley and the flywheel. The belt pulley is intended for a cooling fan at a later stage.

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The flywheel is made from casted iron and the axel is a temporary steel axel and 2 x ball bearings.
Flywheel diameter: 73,0 mm, Width 9,0 mm. Axel: 6,0 mm.

Now I had to paint some other things, and I just added some red color on my project as well. It’s not the final surface it’s far too rough. Once all parts are ready and the engine will run, I will polish and repaint to make the engine look nice.

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The hole for the power cylinder is in place. The brass parts are made from an 8 mm hexagon bar. Some details will have press fit, but I change it so I can use lock screws, then it’s easy to change and adjust parts if needed.

The power cylinder with piston and piston holder, made from brass bars and 8 mm hexagon bar. The brass piston has a tight fit with a low air leaking.

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Power cylinder: L 32,7 mm.
Outside diameter: 19,2 mm.
Inner Diameter: 15,9 mm.
Piston length 16,9 mm.
Piston Diameter 15,7 mm.

Now I can start to see what the engine will look like when all things are ready.

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The crank disk is Diameter 25,4 mm. Thickness: 3 & 3,4 mm. Drilled with press fit to 6 mm axel. Will be changed to a lock screw later.

Today I started with the bushing for the displacer rod.

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The difference from cylinder to displacer is only app. 0,2 mm. This will be difficult to line up and make the piston run clear all the time.

Now it’s time to start with the “nitty-gritty” details, and now it’s time for basic adjusting of the different dimensions.

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The bushing for the displacer is not done yet. The power piston is not pressed into the right position yet. This is just a try to fit things together, and to decide the next step in the work.

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The bushing will be aligned and fixed with plastic metal (maybe). Now the bushing is leaking too much air, but I will adjust that later. Also there will be a small hole for lubrication, the oil will also reduce the air leaking. Now it’s time for the bushing for the displacer piston. No much space to work on.