The Kure Tekko Motor

Primary References:—

Popular Science Magazine June 1979, p80

Japanese Patents JPS55144783, JPS55136867, JPS55115641, JPS55114172, JPS55111654, JPS55106084, JPS55071185, JPS55061274, JPS55061273, JPS55053170, JPS55053160.

Fig 1   Popular Science magazine June 1979, p80

    

Fig 2   Popular Science magazine June 1979, p81

Early Disclosure

The first of several very interesting Japanese electromagnet/permanent magnet motors to 
be disclosed in the West was the prototype shown in Figures 1 and 2 above. Evidently the result of considerable design and development work, and with a radically new operating principle exploiting forces of magnetic repulsion, it was made by automotive components manufacturer Kure Tekko, a.k.a. Kure Tekkosho K.K. Several clues indicate that it was designed to be a free energy motor, although it was not specifically claimed to be one in the Popular Science article.

The Kure Tekko motor is the best example known to me of a genuine magnetic repulsion motor that was professionally designed and manufactured. As far as I know, there has not been any really careful independent examination and comment on what was reported about it. Let's now do that:—

Same principle

An essential part of this motor's operating cycle is the attraction-in of permanent magnets to an electromagnet's unenergized core, followed immediately by repulsion-out of the magnets from the electromagnet, now energized. This, in the drum-rotor Kure Tekko motor, is exactly the same principle as proposed in my disc-rotor "UAER" device (see my posts of 13 February and 5 March 2016).

For the record, my UAER concept dates back to my 1950s childhood. In about 1957 I built a crude prototype of this idea (which would not have delivered any free energy — I was not specifically trying to do that back then). However, I cannot prove that I built that prototype now. The Popular Science Kure Tekko article may well be the first time this principle has appeared publicly.

Patents and inventors

Most of the patents cited above can be regarded as precursor ideas. Only two, JPS55061274 and JPS55114172, resemble the final design described in the Popular Science article, and they have two sets of electromagnets with a 180º operating cycle, rather than the single set and 360º cycle of the final design.

However, when read carefully together, the full set of patents leave no doubt (in my mind at least) that the intention was to invent a free energy magnet motor.

It is often claimed that prominent magnet motor inventor Yasunori Takahashi invented the Kure Tekko motor. I have never found any hard evidence for that claim. His CV does not list any association with Kure Tekko, and he does not appear among the inventors named in the patents cited above.

Item (F)

The detailed colour illustration Figure 2 above would have been drawn from photographs of the actual machine, and also possibly from engineering drawings of it. In this illustration, the most obvious and important clue that this was indeed a free energy motor is item (F), which is described as a "small electric motor" that "crank-starts the rotors." It has a cooling fan. Such fans are used only on devices that run long enough to attain thermal equilibrium, which no starter motor is ever designed to do. Nor would it ever remain mechanically connected and rotating at high speed after starting, as (F) must, via its belt drive. Note that there is no over-running clutch or any other method of disconnecting the drive. Also, since the main motor was claimed to "start" at only about 200 rpm, the speed ratio between (F) and the main motor (as inferred from the pulley sizes) seems very wrong, if (F) is just a starter motor.

So, (F) is something other than just a starter motor. By visual appearance alone, anyone with any experience with cars would identify it as a typical 1970s continuously-running automotive alternator, rather than a starter motor. Could it provide all the electrical energy needed to keep the main motor running in stand-alone mode? A magnetic repulsion motor like this could well require only a small amount of such "self-generated" electrical energy to "top-up" minor losses, and hence to keep running continuously. Of course (F) could be made to act briefly, initially, as a starter motor. (As a general rule, almost any conventional electrical generator can be fairly easily made to reverse its direction of energy conversion between electrical and mechanical, and hence operate as an electric motor, if required).

Power, weight and efficiency

Although the Popular Science article noted that "no performance details have been revealed," power (45 hp) and weight (155 lb) were given. The Kure Tekko motor therefore had a better power to weight ratio than other generally available conventional electric motors of the time. That alone should have caused further interest and investigation, but what in fact ensued was — silence.

The main thrust of the article is that the Kure Tekko motor was designed and built to be more efficient than conventional motors, and hence it seems surprising at first sight that the most important performance detail of all, i.e. an efficiency figure, was not given. However, if an efficiency of over 100% had indeed been achieved, the omission of such a controversial result would become more understandable.

Capscrews into electromagnet cores

In the illustration it appears that the electromagnet cores are fastened to their steel backing plate with capscrews. At first sight, this method of fastening would seem impractical with laminated cores; but lamination would normally be required, to minimise eddy current losses in the cores. 

Perhaps an experiment with solid cores is being shown here? Still, laminated cores could be successfully drilled and tapped for capscrews, if the laminations were first glued together, e.g. with a strong epoxy glue allowed to set under compression. Sometimes such "unusual" techniques are used in prototypes — we see that the motor design allows for easy substitution of electromagnets. This would be as expected for a prototype stated to be in an "early development stage," to permit experimentation with different electromagnet cores, windings and pole pieces.

Metal alloy castings

The article states that "most of the engine castings, including the rotor, are made of light alloy." This would almost certainly be an aluminium alloy, a good electrical conductor, which would therefore have eddy currents flowing in it during operation. Did the designers do a full assessment of expected eddy current losses? I have reason to believe they might have done better to have made these components from non-conducting material such as ceramic, or perhaps a suitable plastic.

Tight clearances

To obtain maximum benefit from the (non-linear) forces of magnetic repulsion which are much higher at small separation distances, the Kure Tekko motor has an extremely tight clearance, for a motor of its size, of only 0.1mm between the rotor magnets and the start of the spiral stator magnets.

Presumably such a tight clearance would not have been specified without good reason — the designers must have considered it essential. It would probably require, among other things, finish grinding and magnetizing of the rotor magnets after they had been assembled into the rotor — routine enough procedures for industry, but not for amateurs. The same clearance of 0.1mm would then also be expected between the rotor magnets and the electromagnet pole pieces. So, careful manufacture of the electromagnets would also have been required.

On the other hand, although the tight clearance gives a very high repulsive force, that force drops back very soon to lower values as the airgap increases, i.e. not much energy can be gained from exploiting even a very high force over a tiny distance.

Permanent magnet mismatch

There is an obvious mismatch between the "cobalt" rotor magnets B (assumed to be samarium-cobalt — alnico would be far too weak and easily demagnetized in a repulsion motor like this) and the plastic bonded ferrite stator magnets E. Was cost the over-riding factor here? Another consideration is that stator magnets made from electrically conducting material such as samarium-cobalt or neodymium-iron-boron would have high eddy-currents flowing in them during operation, unlike ferrite, a non-conductor.

I'll have more to say about this topic in future. Unlike conventional motors, where eddy currents almost always cause problems and should therefore be minimised, there are cases where they may actually be beneficial in genuine repulsion motors.

Ferrite stator magnets would give lower overall performance than samarium-cobalt or neodymium-iron-boron ones, but would also require less electrical energy to be delivered to the electromagnet (because it would require less repulsive force to expel the rotor magnets against the weaker ferrite stator magnets).  Although most of that electrical energy is returned to the source, minor losses still occur, such as Joule heating, which is proportional to the square of the electromagnet current.

Another very important question is — are the stator magnets really worth having at all? More on that next time.

Timing of electromagnet impulse

The article states that the electromagnet impulse "is precisely timed to start after the cobalt [rotor] magnet reaches top dead center..." So there is no doubt that a mechanical energy "bonus" is being obtained, by allowing the rotor magnet to be attracted-in to the unenergized electromagnet core, before the impulse is applied.

Consequently, the electromagnet now has "wrong-way" flux from the permanent magnet in its core, but the question can again be raised of exactly what energy penalty has to be paid to expel that flux, (over and above that required to energize the electromagnet anyway).

Request for update?

Bloomberg Business Profiles has Kure Tekkosho K.K. currently at:—

1-8-15, Hirotagaya, Kure, 737-0134, Japan 
Phone: 81-823713121 
Fax: 81-823740698

I suppose an attempt could be made to contact them for an update on what happened with their motor since the Popular Science article, but personally, as an ordinary member of the public, I gave up on such attempts long ago, having had zero response to every one I had ever made.