electric motors

[Don1966]

OK,  the solenoid has a long power stroke because the piston has a magnetic pole which is always inside the coil.

It is not usually possible to make a magnet with three poles but that is in effect what I did.   

If you place two magnets with like poles adjacent they will repel,  if you place them on the ends of a short bar with like poles towards the ends of the bar they will be repelled.  But if the bar is long enough they will stick to the bar and if you check with a compass needle you will find there are is a single strong pole induced in the middle of the bar,  actually it is two like poles very close together but for our purpose we can consider them a single pole.

That's cool John have you tried to make it run faster by timing the on time? And I believe the principle is called consequent pole action. In other words it forms an imaginary pole. That principle it use in motors where the windings will be connected all north or all south poles and the imaginary poles are formed in between them producing the required poles.

Don

[John Hill]

Thanks Don,  consequent pole action does seem to be the same animal.

I was not seeking high speed as there seems to be no shortage of high speed solenoid engines but I was looking for a long, even, power stroke which I could prove by the engine being capable of slow running.   Experiments with electronic kitchen scales showed a very even thrust throughout the stroke where the consequent pole(s) moved almost the entire length of the solenoid.

[PStechPaul]

Any chance of some pictures of the internal construction? I assume the solonoid is a continuous winding over the length of the cylinder, and would have N and S poles on the ends, which would reverse at the end of the stroke. The electromagnetic field would attempt to create an opposite set of poles in the plunger, but this will also react with the permanent magnet. Exactly how, I don't know. 

[John Hill]

I would have to destroy it to photograph the innards!

The solenoid coils are just like you describe, with a N pole and one end and a S pole at the other.  The 'piston' is effectively a single bar magnet with a like pole at each end (N for for example) and a opposite (S) pole midway along the bar.

The significant characteristic of this engine is that the induced pole (that is the one in the middle of the bar) is always right inside the solenoid coil and is being drawn to one end while being repelled from the other,  obviously the solenoid polarity is reversed twice per revolution.

[BillTodd]

Doug has some interesting antique designs on his site :

http://www.douglas-self.com/MUSEUM/POWER/eleceng/eleceng.htm

[Graham G]

Hi to all,  It seems I have overcome enough of the techno gibberish to finally get a video on this post.
(I hope it works).
This motor is in the rough just so I could work out the scale etc. and I will be building another one with a more appealing visual concept, although I think you guys can see where I am heading with this one.
I decided to go very simple with the timing of the magnetic exciter, and used a cam and micro switch assy which works well for what it is.
The solenoid is out of a printer (i don't know the make or model sorry) the numbers on the coil are as follows, SOLEN TADYUAN  stc-tu1939 12 v d/c and it came with the piston.
My son very generously gave me 2 of these coil assy's from a printer he wrecked.
Your comments are most welcome so as the next will be a vast improvement over this one, many thanx in advance.
Graham.

[PStechPaul]

Pretty cool!    It's hard to tell from the video how fast it's running. It appears jerky, but it's probably because of the video frame rate. 

[fcheslop]

This site has some very nice early elect model motors
http://www.earlyelectricmotors.com/
I keep looking at the Froment
cheers

[Graham G]

Hi Paul, Yes I think it is the frame speed and for some reason I took another video of it with the same results so it's time to get a real (brand name) digital camera with a video mode.
I used the computer camera (usb plugin type) to get the posted vid.
All comments/ criticism most welcome.
Graham