[Prajna (OP)]

Hello all, I have been playing with switching magnetic flux by interposing a sheet of soft iron between two opposed magnetic poles.

I have posted about this on scienceforums[ dot ]net but would appreciate a deeper and wider discussion.

I guess everybody knows that two opposing magnetic poles repel. I discovered - it may be obvious really - that inserting a sheet of ferromagnetic material (soft iron, electrical steel, plain mild steel, etc) in the gap between two opposing magnetic poles causes the magnets to be attracted towards the sheet. This has the practical effect of switching the magnets from repulsion to attraction. Removing the sheet switches the magnets back to repulsion.

I have used this effect in the design of a number of devices that employed a rotor with ferromagnetic tabs or 'fingers' spaced around its periphery that intersect the magnets so that the flux field switches between attraction and repulsion and using the reciprocation that induced to induce a rotary movement in an output rotor.

The latest iteration of my design looks as follows:


labeled.png (169.96 kB . 763x530 - viewed 342 times)

In this design there is a cylindrical rotor that has two opposing sinusoidal cam grooves running around the sides of the cylinder. There are carriages arranged on shafts that constrain them to move parallel to the cylinder and the carriages also have a bearing that runs in the cam grooves. The carriages are arranged in pairs and each carriage also has a magnet. The magnets are arranged so that they oppose the magnet in the opposite carriage. Wherever the cam tracks are converging there is a metal tab that will attract the magnets either side of it. Wherever the cam tracks are diverging there is no tab, thus the magnets are repelling.

Where the magnets are attracting the cam track is converging and thus the vector force of the bearing on the cam track will cause the rotor to rotate to the left (in the above image). Where the magnets are repelling the cam track is diverging and thus the vector force of the bearing will also cause the rotor to rotate to the left.

At the extremes of their travel the vector force of the bearings will be perpendicular to the track and thus will impose an axial rather than rotary force on the rotor. Since there are five waves in the cam track and four sets of carriages, opposite carriages will be at opposite extremes whilst adjacent carriages will be in the mid point of their travel. This means that while the carriages at their extremes and imposing an axial rather than rotary force on the rotor, the adjacent carriage pairs will be exerting a rotary force on the rotor.

It appears to me that this device should start running as soon as it is assembled and require no energy input to start or continue it's motion.

Am I wrong? The laws of thermodynamics would suggest so, however such a general rule does not explain what is happening in this device. Can anyone comment on why, given the geometry of this device and the arrangement of magnets and interposed low-reluctance paths, this device would not behave as I suggest?

There is more info about the device on my website: tomboy-pink[ dot ]co[ dot ]uk/sfmm
There is an simulation of the device running at: youtu[ dot ]be/mjZMPHsw5po
The complete CAD model is available at: github[ dot ]com/prajna-pranab/sfmm-Mk1

[Bored chemist]

Or you could just buy one.
https://www.first4magnets.com/other-c89/63-x-50-x-55mm-high-switchable-magnetic-base-with-m8-mounting-hole-70kg-pull-p3473#ps_0_3563|ps_1_1527
Many other brands are available.

[Prajna (OP)]

Or you could just buy one.

Your response doesn't answer the question I asked: will the device I described behave in the way I suggested it will?

[alancalverd]

Am I wrong?

Yes.

There have been umpteen perpetual motion machines proposed using permanent magnets. My father was approached by one inventor looking for investment (always a bad sign - if the prototype generates more power than it consumes, just sell the surplus and use the profits to build a bigger one!) who claimed "I have had perpetual motion for twenty minutes."   

[Bored chemist]

Or you could just buy one.

Your response doesn't answer the question I asked: will the device I described behave in the way I suggested it will?

Here's how you described it.

Am I wrong? The laws of thermodynamics would suggest so,

I didn't think I needed to confirm it.

[Prajna (OP)]

...

Still doesn't address the question. Certainly not with reason. What's so difficult about analysing what forces are operating in this machine and commenting on why it would behave differently than the way I suggest it will. Is there something wrong with how I have described the device or the observations I have made about how and why it should operate? Can anyone address those questions rather than pontificate about perpetual motion machines in general?

[alancalverd]

You can analyse the torque/rotation curve and find the minimum for yourself.

[paul cotter]

All these schemes for changing/modulating the field of a permanent magnet fail to sum all the input/output energies. For example removing the ferromagnetic material between the two opposing permanent magnets will require energy: in a perfect lossless system this energy will exactly equal any gain resulting from the altered fields and in practice it will exceed any gain.

[Prajna (OP)]

All these schemes for changing/modulating the field of a permanent magnet fail to sum all the input/output energies. For example removing the ferromagnetic material between the two opposing permanent magnets will require energy: in a perfect lossless system this energy will exactly equal any gain resulting from the altered fields and in practice it will exceed any gain.

Certainly there will be force required to pass a ferromagnetic sheet through a magnetic gap. The field induces eddy currents in the sheet and, being an opposite field to that of the inducing magnets, it will create drag. My experiments, though somewhat rough and ready, seem to indicate that moving the ferromagnetic sheet transverse to the field does not seem to cause as much drag as you would expect and I believe the force required to do so is less than the force of the attraction/repulsion forces. I may be wrong in these observations but, as nobody with a good understanding of magnetic fields and forces seems prepared to analyse what is happening with the attraction/repulsion forces and the eddy current drag, I am in the process of building this device in order to empirically test my assumptions. Thanks for the intelligent reply.

[Prajna (OP)]

I've updated the web page for the device detailing the control mechanism that allows the device to be started in forwards or reverse rotation and to be stopped when running. (Just in case anyone is interested.) I'm rather pleased with the way it has turned out and has fitted into the device and I think it is worthy of a patent by itself (if I was into patenting.)

The control system toggles the device off whether it is rotating forwards or backwards, is simple and has few moving parts.

Info at tomboy-pink[ dot ]co[ dot ]uk/sfmm/

[alancalverd]

I think it is worthy of a patent by itself

If you apply for a patent, the inspector will tell you why it won't work and isn't patentable. If you don't apply for a patent, you are giving away the most significant invention the world has ever seen.

[Prajna (OP)]

If you apply for a patent, the inspector will tell you why it won't work and isn't patentable. If you don't apply for a patent, you are giving away the most significant invention the world has ever seen.

What won't work? The control mechanism? If the device is the most significant invention the world has ever seen then why would I seek profit from it? Surely such a device would profit me as much as anyone and making it freely available opens it to development and improvement by many different minds.

[alancalverd]

Surely such a device would profit me as much as anyone

Not as much as the guy who does patent it and thus prevents you (or anyone else) from making one.

[Prajna (OP)]

Not as much as the guy who does patent it and thus prevents you (or anyone else) from making one.

Something wrong with the patent system if one can patent prior art.

[alancalverd]

A patent is for a means of doing something. Since your device won't do anything, your patent would be refused.

[paul cotter]

In reply #5, the OP wonders why there is so little interest in analysing such setups. The reason is as follows: those educated in these matters understand that the magnetic field is conservative, as are the electric and gravitational fields. This informs us that in a cyclic system that returns to the same point there can be no gain in energy, regardless as to how it is configured. Hence the rotor will not self-run. Very little in science is more certain than these restrictions however disappointing they may be.

[Prajna (OP)]

...

Thanks for the response Paul. It sums up nicely what is wrong with science: scientists don't question what they think they know. Thanks to "laws" like conservation of energy you shortcut examining anything that looks to challenge those "laws". But that doesn't enlighten anyone as to why - specifically, analytically - this device won't work. It looks logical: the magnets are in attraction where the cam tracks converge and in repulsion where they diverge and in both cases that will impose a vector force on the cam track causing the rotor to rotate. Is there something wrong with that analysis to begin with?

Even as an intellectual exercise it is an interesting problem, n'est'pas? It seems not so when it comes to scientists and physicists in particular. There is a more certain law than thermodynamics and conservation of energy and that is that physicists cannot entertain, even as an intellectual exercise, any challenge to their dogma. But science is the history of challenging dogma, though, as Max Planck said, "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather its opponents eventually die, and a new generation grows up that is familiar with it."

Perhaps this device doesn't contradict the conservation of energy at all, perhaps it is just that the way we define conservation of energy is not specific enough in this case. I seem to recall that it only applies to a closed system. Do we know for sure that magnetism does not cross some boundary? Sub-atomic particles flash in and out of existence, or perhaps in and out of our dimension, are we sure that there is not a similar effect with magnetic fields? But nobody is prepared to even examine such questions because "conservation of energy."

There is another anomaly with physicists: they know for sure that there can be no such thing as a perpetual motion machine and yet they can recognise such a thing (and shut their brain off) instantly.

I'm sorry to rant but I am frustrated that nobody will discuss the geometry of this device and point out - by referring to the device's geometry and magnetic fields - why this machine will not work as I have suggested it will. Being told, "blah, blah, conservation of energy, blah, blah, laws of thermodynamics, blah, blah, ..." feels like being told, "Because I say so!" by a teacher who doesn't know the answer to some question. That is not aimed at you specifically, Paul.

I was told by one physicist that he had never been confronted with such a complex problem in all of his university training. Perhaps that is the real problem: it is not simple to analyse what is happening in this device and therefore far easier to dismiss it by simply stating that if it did work then it would negate conservation of energy and therefore it can't work and therefore it isn't worth thinking about.

Surely somebody has enough familiarity with magnetism to, at least approximately, point out where in the rotation is the "sticky spot" - where the force vectors are wrong or the geometry prevents them acting or some other consideration. But we never get to such a discussion because you guys (and all the other scientists I have found to discuss it with) can shortcut the discussion with variations on "conservation of energy."

[paul cotter]

You are quite wrong in your view of science as none of the "laws" are set in stone and all are open to challenge but to falsify a law one needs solid reproducible experimental data. Dogma is what one finds in religion, not in science. However it is possible to find dogmatic individuals involved as it is in any area of human pursuit. Most people who claim science is dogma have never been educated in it and if they were the results would be different. During a science course there are two important parts, theory and practice. In lab work students are required to recreate the historic experiments that led to our current understanding so that they can see for themselves the validity of the laws for themselves rather than just accept what they are told in the theory work. In more advanced levels research becomes important and all aspiring scientists seek to find something new whether it be a new chemical compound, an exception to a law, a new theory that explains previously unexplained phenomena, etc,etc. Science is driven by the pursuit of novelty and is always moving forward. The laws that we have currently are the best fit for what we observe but there is every possibility that they may be improved upon in the future but this is not guaranteed.

[alancalverd]

Surely somebody has enough familiarity with magnetism to, at least approximately, point out where in the rotation is the "sticky spot"

Let's cut to the chase.

You can do this yourself by simply looking at your design and calculating the torque at any point in the rotation. Or just build it and see what happens.

If the laws of physics are wrong, you can bring me a working prototype built to your specification. I will help you apply for the necessary patents (in your name as sole inventor) and raise capital to get it into mass production.  Nobody will invest if it isn't (a) demonstrated and (b) patented.   

My fee will be 1% of the factory-gate sale price for every device that incorporates the agreed design - we'll let the lawyers sort out the details. What you do with the rest of the money is entirely up to you - you can mirror the Gates Foundation if you want the world to benefit, or spend it on "slow horses and fast women", as you please. 

[paul cotter]

Now there is an example of a professional scientist with an open mind for you(op). It is not all dogma as you suggest.