The Kozeka Principle Part II

Magnets with non-linear demagnetisation curves

So far I had only looked at neodymium-iron-boron magnets, which have linear demagnetisation curves. Would magnets with non-linear curves do better?

Repulsion force graphs for two 96 × 60 × 8 Feroba2 magnets (upper),
and for two 50 × 50 × 150 Feroba2 magnets (lower)

Here are two sets of results for repelling Feroba2 ferrite magnets. (Note that for all these repulsion graphs, repelling forces are now defined as positive. This was done for easier comparison with attraction graphs for similar pairs of magnets).

Once again there is negligible energy difference between horizontal and vertical repulsion.

A significant energy gain — but probably only a "one-off"

Repulsion force graph for two 50 × 50 × 150 Alnico5 magnets

Here are results for a large pair of Alnico5 magnets (150mm high), repelling. At last, here is another potentially interesting feature:— there is a significant energy difference. The energy gained by horizontal repulsion is over 5% higher than that expended against vertical repulsion. However, I'm fairly sure that what is really happening here is that the modelling program is showing only a "one-off" energy gain. In practice, repelling alnico magnets like these would be permanently demagnetised to a significant extent during the first time they were placed close together, but the program is not taking account of the already largely demagnetised state of the magnets, which is what would exist for all cycles after the first one.


Conclusions

1. It is possible that with further work, a very low-power permanent magnet motor could be made using magnets with very non-linear demagnetisation curves (such as Alnico), perhaps even with the magnets significantly demagnetised. The Bowman motor is a possible example, which I'll look at next time.

2. Since, unfortunately, I cannot see any way of avoiding the energy "well" previously discussed in Part I, it is not worthwhile for me to investigate the Kozeka idea any further.

The Kozeka Principle Part I

Primary references:—

http://www.kedroncorp.com/abstract.html [now only available archived; e.g. at https://web.archive.org/web/20080615010715/http://www.kedroncorp.com/abstract.html], and search http://peswiki.com/index.php/Main_Page for "kedron".

Kozeka principle:— a difference is claimed between the energy delivered
when two magnets attract horizontally, and the energy required to separate them vertically

Summary of operating principle

In 2007 Dr Kenneth Kozeka claimed that there was a difference between the energy delivered when two magnets pulled together horizontally, and the energy required to separate them vertically. He claimed that two NdFeB38  3/4 inch cube magnets "... are capable of generating 7.46 inch-pounds (work) when they pull themselves together “sideways” in the horizontal plane. It takes only 6.56 inch-pounds to pull the magnets apart along a vertical path that is perpendicular to the path they followed when they came together. This leaves a .90 inch-pound net-yield of mechanical energy (work) which can be used for example to turn an electric generator."

Kozeka's graph of attraction force vs distance. The units for the axes are not stated

I decided to model Kozeka's idea exactly as described above (except that I used NdFeB39, which was already in my program's library, instead of NdFeB38.) Ansoft Maxwell v11 was the magnetostatic modelling program used. The results when plotted out gave the graph shown below.

My results for attraction force vs distance

Integrating the attraction force curves to find the energies gave negligible energy difference between them, i.e. 0.6957J = 6.157 inch-pound versus 0.6929J = 6.132 inch-pound. (The difference is well within the 1% energy error I used to define "solved" force calculations).

Further Investigation

These results showed one potentially interesting feature: although it is hard to see in my graph above, the horizontal force goes slightly negative for a while. I decided to investigate this further, with larger but thinner magnets.

Modelling of two 96 × 60 × 8 NdFeB45H magnets

For the two 96 × 60 × 8mm NdFeB45H magnets shown above, this effect becomes much more prominent (note how the blue horizontal force curve goes significantly negative beyond about 61mm of separation):—

Attraction force vs distance for two 96 × 60 × 8 NdFeB45H magnets

Can the "energy well" be avoided?

Once again, if the magnets are brought in from "remote" positions, there is no net energy difference. But, if it were possible to start the horizontal movement with the magnets separated no more than about 61mm, and to keep returning to such a starting position with little or no energy penalty, there would indeed be a large excess of energy to be gained. Unfortunately, it seems to be impossible to avoid the energy "well" involved in bringing the magnets together to this desirable starting position. I have looked at repelling instead of attracting magnets; at movement along each of the three orthogonal axes; at diverting the flux of one or both magnets into steel "shields" over part of the operating cycle, etc, but have never found any way of avoiding this energy "well", to the extent that any significant excess energy can be gained.

A version of the Kozeka principle with the magnets enclosed within low-hysteresis
steel shields over the energy well until they have reached the desirable starting position.
However, no net energy gain has been found with this approach.

Next time I'll look at versions of the Kozeka principle where, in one case, a significant energy gain is indeed achieved (but it is probably only a "one-off" gain).

An Early Attempt at a Magnet Motor

Here are some images of an attempt I made many years ago to make a permanent magnet motor. 

This device was designed around the alnico magnet assembly of an old loudspeaker. The general idea was that there would be attractive forces pulling together the two salient (toothed) rotors, in the 180 degree region in which they were completing the magnetic circuit; that they would be able to move apart again easily where there was much less magnetic flux between them (over the remaining 180 degrees); and that this would cause both rotors to turn.

Although the brass items, the turned steel items and the blanks for the rotors were of course made with a lathe, all of the rotor teeth were made by cutting with a jigsaw and a hand hacksaw, and finishing by filing. The cutting away of half the speaker steel assembly was also done with a hand hacksaw.

Years ago, I used to enjoy working in these "old school" ways. Nowadays I usually find them too tedious, time-consuming (especially when accuracy is required), and too much physical effort! I also grew tired of ending up with magnetised files, hacksaw blades etc. I now prefer, where possible, to use quicker and more efficient methods like laser-cutting, (although I don't have my own laser-cutter yet).

Nowadays I would always model a device like this first, using a magnetostatic simulation program capable of predicting the expected forces and torques, before I would ever consider building a physical prototype. Such a program would no doubt have told me what I found out from this prototype — it doesn't work!

Years later I did make a computer model of a development of this idea that did deliver a small amount of excess energy, and I'll discuss that in a future post.

General Comments, and a Glimpse Forward

I'm back

I'm now back from my hiatus. This was largely a case of déjà vu. When I took early retirement from professional engineering over a decade ago, I had hoped that I might no longer be heavily involved in catching and correcting the errors made by others — some with potentially serious consequences. Unfortunately, that hasn't always been so.

A step forward mechanically

I had left my investigations into mechanical perpetual motion more or less as in my posts of 18 April to 9 May 2015. However, I recently made a fairly significant step forward. As things stand, I could perhaps in theory design a perpetual motion wheel that would at least reach my self-imposed lower limit of one watt power output per kilogram of active mass. Unfortunately, the wheel would have to be extremely large — far too large to be practical.

Obviously the wheel must be compacted-up. There is a possible way forward to achieve this compaction, but there will be a lot of work ahead.

Magnet motors next

As I said at the outset, I had intended this blog to be mostly about my investigations into the interactions between permanent magnets, and between electromagnets and permanent magnets. I'll still look at those topics next, but not always in such detail as I had originally intended. Also, because of my foreseeable future work on a mechanical device, as well as ongoing "fallout" from other issues, I'll only be able to post once a fortnight or so.