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4 piston solenoid engine overview       During the summer of 2008 I was interested in alternative engines. While researching and doing some thinking, I found videos of solenoid engines on the internet. I quickly became fascinated with the idea.

     I decided to build my own solenoid engine and I noticed that all of the models I found were one or two pistons. I wanted to make my engine more unique so I designed it to have four pistons.

    The picture to the left has labels over the major visible components of the engine.

first try pistons with connecting rods

     These are the original pistons (magnetic cores not shown in picture) with crankshaft attachments that I designed for the engine. I kept the pistons but had to abandon the crankshaft attachments, the black plastic parts. There were two problems with these crankshaft attachments, friction and flexibility. The wood axels in the crankshaft did not lube well and the overall assembly would flex under any stress. The consequent engine would not rotate under its own power.

     I switched to metal axels and acrylic sleeve bearings for the crankshaft. The new crankshaft has much less friction, better rigidity, and as a bonus it looks better. This version of the crankshaft can be seen more closely in the second to last picture.


Solenoid build process

     The metal coils for the engine were made in three steps. First I glued two metal washers to a section of copper pipe to create a core, then I wrapped the it electrical tape for insulation, and finally I wrapped eight layers of 28 AWG wire around the core. Looking back, it would have been better for the efficiency to have used plastic for the core rather than metal. When a magnet moves through a copper pipe there is a resistive force cause by eddy currents induced in the copper. Not to mention the fact that magnets are attracted to steel washers.


Solenoid engine crankshaft close up

     Here is a shot of the final crankshaft assembly. For the metal that replaced the black parts in second picture from the top, I used old erecter set parts because they came predrilled and I didn't have the tools for properly machining metal. The black disk on the left is a flywheel which is made out of a metal plate I got from an outdated pair of snowboard click-in bindings. For coil timing I put two wire brushes on the left two piston rods. The contacts for these brushes were removed for the picture ( part of it can be seen as the blue part sticking into the picture at the bottom left).


Solenoid engine exploded view

     There was a reason for the white box. When I initially started the project I thought the engine might be prone to over heating so I built a box around the solenoids that could be filled with mineral oil. Thankfully no oil is necessary, the coils warm up but by no means do they get too hot when operating at 12 volts.



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