dknespl
25
T coef
COSC criteria is 0,6 sec/day/0C, which is 0.6/24/3600=~7E-6, i.e. 0.0007% change of period due to change in temperature of 1 0C.
The best current sammarium cobalt permanent magnets have RTC 0.002%, i.e. a change in magnetic flux Br per degree Centigrade is 0.002%. on the range -50 +150 0C, which is definitely not the range we would need for a wrist watch. Cosc requires range from +8 to +38 0C, so on such a narrow range it could be even better.
The problem is, that I do not know the formula how period depends on Br. Is it a linear function of flux?
In any case I would not be that skeptical, I would say we are almost there 
Can anyone explain the Tag Pendulum concept?
Can anyone explain to me how this movement works? I have been trying to understand why it changes direction in its oscillation, and also how it is regulated. Clearly is must oscillate back and forth because it appears to use a lever escapement. From the p...
This image clarified the mechanism for me...
I have also looked through all of the promotional material and this image was the most clarifying media in terms of presenting how the mechanism works. As the description states, the magnets generate the linear torque that drives the alternative oscillati...
Thanks, did not see the info on Tag's site
Thanks, I did not see the concept watch link on the Tag site (until your mention got me to look again) so I hadn't seen that description, which was much more complete than what I had previously found (baselworld site and various postings of the press rele...
Don't know what to say about that idea...
-Why the need for a balance wheel when there's a heavy magnet rotating? -Why replace the spring when the much heavier magnet is going to make adjusting in positions a rather interesting proposition... Solution looking for a problem...
Interesting point...
Also seems like magnetic field protection would be even more crucial. It seems like a production version would need extensive shielding which would make sapphire back impossible. I can't wait to see more info! B
balance wheel
I think you need a kind of balance wheel. You need a moment of inertia which is weight x length of the arm (I=mr 2 ). If you would have the gyrostat made just of the magnet in the center, it would have to be much heavier in order to have the same I. Since...
ummm...
...if you look at the design, the magnet is rotating on the same shaft as the balance wheel...and if that diagram is anything approaching scale, it's going to have a hugely larger PMOI than that cut away little wheel. So why the need for a balance wheel o...
balance wheel continued...
As I wrote, mass in the center where r->0 is not adding much to the total I, if I=mr^2, or we should rather write \int r^2 dm, The frequency depends on one side on the strength of the magnetic field and on the other side on the moment of inertia and they ...
Umm..part 2.
"It would be a magnet and a balance wheel in one part. Is it what you mean?" Yes. Should have worded that better. Regulation via screws, If I'm interpreting you correcty, you're saying that the balance wheel is required to provide the opportunity for fine...
working prototypes
This time, there were 5 working prototypes on the Basel booth. You might say that it's a shame to show non finalised concepts, but it's the only way to make big steps. Like you can see on this forum, skeptical comments could have killed the project. Once ...
There we are...
Point by point : No need of a balance wheel if the magnets would have a larger radius : need to be studied. It would be a complete reconstrustruction of the system and I have no idea of the answer... It's true that with a larger diameter it would be easie...
Hello Thomas..
Thank you for spending the time to respond here. Very much appreciated and informative. The thing to see would be the images of the magnetic fields as the rotor moves, if this was modelled.....would answer a lot
Magnetic fields images
I think those images would have been slightly too technical for the press file ! Only purists could appreciate them. Let's chek with the ingeneers on tuesday what could be shown. Best thom
Very much appreciated...
No need to have any numbers on the images, any data on field strength and direction would be fantastic.
fields protection
The system might need to be protected from external magnetic fields. May be not a lot more than a standard hair spring, but definitely a lot more than a non magnetic hairspring...
magnetic fields have no weight...
Tha mass of the rotating magnet (the rotor) is not enough to replace the balance wheel. But why not in a completely new conception ! The spring has been replaced by magnetic fields because magnetic fields have no mass. The problem with the hair spring is ...
I wish them luck, lots of luck...
They should have taken the time to look at the coefficients of magnets over temperature before starting out. The field strength of permanent magnets changes greatly with temperature. I can't imagine that such a system could ever be made to be COSC and hav...
temperature
I think it is a know issue. It was even stated in the press release, that of course dependency on temperature is a big issue. They say that they wait for the "magnetic Nivarox"
Good point, Don.
I was coming at the concept more from a proof-of-concept POV. Excellent point re: stability of field at temp. I'll have to have a look at some books to determine the variation in strength over the COSC temp range...But even fraction of a % will throw it r...
T coef
COSC criteria is 0,6 sec/day/ 0 C, which is 0.6/24/3600=~7E-6, i.e. 0.0007% change of period due to change in temperature of 1 0 C. The best current sammarium cobalt permanent magnets have RTC 0.002%, i.e. a change in magnetic flux Br per degree Centigrad...
Temperature / magnetic fields
What I learned from the engineers working on the prototypes is that the variation is of 0,0018Hz / °C, which is far too much for a movement beating at 6Hz to reach the COSC. So either the temperature variations will have to be mechanically compensated (a ...
materials
But I think, chances are, that new materials for permanent magnets will appear, that have somewhat better temperature coefficients. I think the research is going on, if not because of magnetic watch balances, the because of traveling wave tubes (radio fre...
Magnets materials
Yes you are right, the technology around magnetism is evolving very fast. Anyway we need to implement a solution before waiting for the perfect material to appear... thom
Patent
I think it is based on patent US7396154 by TH from 2007 (but the original application is even somewhat older) . You can find it on freepatentsonline for example. There are interesting diagrams and more explanation. It also refers to some other simmilar co...
First patent
Well yes this is the first patent. And further patents with more technological solutions are pending to complete the protection of the full concept. You can see on this first patent that the original idea was quite naive ! We did the very first protoype d...