Solenoid engine

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John Hill
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Solenoid engine

#1 Post by John Hill » Sun Sep 20, 2015 12:24 am

I made a little engine to prove my ideas regarding solenoid engines...

http://flic.kr/p/az9wqs



... I dont know why the audio is so loud as the engine is really not quite that noisy..

As you can see this is a two "cylinder" machine and each cylinder is double acting. That may seem an odd way to arrange things but the double magnet and pole piece that makes up each armature is rather heavy and having two like this tends to balance things somewhat.

The engine can run quite slowly, just a little slower than in the video and it will even run without the flywheel. I think this demonstrates the long power stroke achievable with this arrangement of the armatures.

It is running on about 24V in the video and it goes quite a bit faster if I wind up the voltage to the maximum of my power supply which is 36V. The solenoid coils are quite happy and show no sign of heating at 100V which I suspect would be beyond the capability of the very light weight crankshaft I have made in this engine.


Here is a diagram showing the poles of each armature (i.e. 'piston').....

Image

Each armature consists of a soft steel rod about the same length as the solenoid core. Neodymium magnets are attached to each end with LIKE POLES outwards! If you tried to do that to a short rod the magnets would repel but when the rod is long enough the magnets attach to the rod and each induces a pole close to the centre of the rod. These two induced poles are of the same polarity and the result is that the rod appears to be a magnet with like poles at each end and a very broad opposite pole in the centre. The result is that there is a solenoid and armature that produces almost consistent force for the length of the stroke. Obviously the induced poles never move outside the solenoid. Kitchen scales prove the theory and force is indeed fairly consistent.

This engine was built to prove my ideas on how a slow running solenoid engine could be built. There is of course little demand for solenoid engines in the real world but hobbyists like to make them as they are generally simple to build and as the web will show they can be built with minimum tools and everyday materials while at the other end of the scale we can readily find pictures of absolute works of art but most share an inability to run smoothly and at slow speeds.
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John Hill
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Re: Solenoid engine

#2 Post by John Hill » Mon Sep 21, 2015 6:32 am

Image

A simple demonstration of the apparent pole positions in the solenoid motor armatures..

As you can see the red and the blue magnets are mounted on swivels. Two red magnets show they are attracted to the ends of the assembly but the centre red magnet is repelled. Two blue magnets are shown being repelled from the ends of the assembly and the centre blue magnet is attracted to the centre of the armature.
Been in data comm since we formed the bits individually with a Morse key.

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Re: Solenoid engine

#3 Post by Dushan » Mon Sep 21, 2015 3:55 pm

Does this come only in regular Lego or does it come in Duplo version as well?

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