Yes it keeps happening. I suppose once a patent expires you are free to invent it again.
I can't think of a direct example of a permanent magnet axial from the early era. The early permanent magnet stuff was radial. I suppose we could just about get Pixii into this category PM axial.
The early axial machines of Feranti, Mordey, Siemens etc were electromagnet. A clever patent would just say magnet and cover the lot. Not sure how much of the early stuff was patented anyway.
It does bother me that anything pre 1950 seems to have been totally forgotten and the world just seems to reinvent it rather than build on what has been done before.
The people that run the patent offices are pretty clueless and would never realise that there is nothing new in this.
Universities are particularly bad at reinventing the wheel, I suppose that if you are going for a PhD on something done a few years ago you might as well go for a patent.
Flux
