BUILD THE SPIDER STIRLING ENGINE

By Tiny van den Boom

I've named this Stirling engine, made with with eight tumblers/rockers, Spider, because it looks like a giant spider when it is in action. This engine is my own design, based on earlier models I've made. I've translated the corresponding principles of operation into a 4-cylinder Stirling engine. Some of the parts are based on Jan Ridder's drawings.

The challenge was to design and build a Stirling engine which would work with four heat and four working cylinders. These eight cylinders in total would be balanced by means of a large camshaft which would translate the rotation to a flywheel through a belt.

The whole machine is built using a conventional milling machine and a conventional lathe.

The heat cylinders and displacers are made of Pirex (Pyrex) glass so the operation of the cylinder can be seen easily. This glass also preserves heat when the flame is extinguished. To use the heat from the flame as efficiently as possible I've also used glass windshields, which centralize the heat below the Pirex glass. These make it possible to use the engine outside, too. To ensure correct height adjustment of the flame I've made the burners adjustable. This also makes it easy to position the windshields after the wicks are lit.

By placing the tumblers at a suitable height I have managed to limit the friction between the rods and camshaft to a minimum because the rotation between rod and tumbler remained small. In addition, these rods have sufficient length so an optimal alignment could be generated. So that the engine coulld run run as smoothly as possible, I used ball bearings in the most important pivot points, including the tumblers.

The air movement from heat to working cylinder flows through a pipe outside the mounting plate for ease of manufacture. Additionally, this gives the product an extra technical look. By means of a valve between the heat and working cylinder, the pressure can be regulated so the speed of the flywheel is adjustable. It's also possible to drive something with this engine by means of a pulley on the axis of the flywheel.

For anyone interested sets of (approx. 35) drawings of this Stirling engine are available for a fee. Contact me by email. tinyvdboom@gmail.com