STEORN DEMO LIVE & STREAM in Dublin, December 15th, 10 AM

[marek]

Hi marek,

Thanks for that important info! I just knew it, that it was due to magnetic viscosity. Since you studied the Steorn patent already, what type of magnetic core do you recommend?

That I don't know, and patent says nothing about that. It just measure system. I think it must be set experimentally. It will depend on operating conditions (rpm, torque). When you look at the torque-flux chart I would try to run it at higher rpm, because you need less energy to desaturate core. But really, it has to be experimented with different cores materials. Worth thing to notice is that maximum torque is in quite narrow range before core, and drops to 0 when passes it. Negative torque too comes later, so maybe the electric pulse can also be lagged, and duty cycle can be reduced... Speculations;)

[k4zep]

I just took a look at the Steorn patent, and am amazed that it's all there, like marek said. They show everything from tons of magnetic viscosity plots to the design and theory. Steorn is legit! 

http://www.google.com/patents?id=1dOyAAAAEBAJ&zoom=4&pg=PA1#v=onepage&q=&f=true

Right on Paul, soneone else finally read the patent!!!!   Reall exellent work...   

Ben

[captainpecan]

@PaulLowrance,

Yes, groundloop is right.  I always drill my magnets into the rotor whenever possible.  I use a Forester bit. Costs a couple extra dollars, but it makes perfect flat bottomed holes for round magnets.

This is what I was referring to that you can do with that hard drive platter.  This is not my Orbo replication, just a couple pictures of something else I'm working on also.  Hope it helps, it's pretty simple to do, and it lets you easily mount whatever you want to the rotor, while still using that awesome hard drive bearing!

[gyulasun]

Hi Folks,

Steorn has another patent publication on Torque measurement of a rotating body, see here:
http://v3.espacenet.com/publicationDetails/biblio?DB=EPODOC&adjacent=true&locale=en_EP&FT=D&date=20090716&CC=WO&NR=2009087476A2&KC=A2


Abstract of  WO 2009087476  (A2)
A system and method is provided for determining the torque and kinetic energy of a rotating body without contacting the rotating body. Graduation markings are applied to mark regular angular displacements on the object. Reflected laser light from the graduations is sensed and converted into a pulsed signal. The pulses of the signal are time stamped and used to determine the velocity of the rotating object at angular displacements which can be less than 360 degrees. Changes in angular velocity during each rotation can be measured and used to determine changes in torque and kinetic energy during each rotation.

rgds, Gyula

[callanan]

Hi All,

Regarding Steorn's design and claim that the magnet's field on their motor does not induce an emf in the toroid coils, in an ideal world this should be correct. But in the real world nothing is perfect.

Using store bought chokes with few turns will typical keep this induced emf down to the 1-10mV range. But as you all start to wind your own toroid coils on ferrite cores with many more winding turns and winding imperfections then the store bought chokes, this non-ideal induced emf will get larger and typically it can get up to 100mV.

This induced emf due to the coil's imperfection can also make the coil slightly polarity sensitive. Normally, with perfect coils, the polarity of the coil connection does not matter because the direct link between the electrical energy in the coil and the rotor magnet's field is broken. But with imperfect coils where there is a slight induced emf in the coil, this induction creates a link to the rotor magnet's field and will effect the performance of the motor, slightly, depending on the amount of induced emf.

Undertanding this, the induced emf then become very important when using multiple coils around the rotor on your test motor. When you engineer and build your motors, magnet and coil placement as well as even magnet field strength becomes very important. This is because each imperfect coil's induced emf can become additive. But by specially checking for this with a scope and connecting the coils together with specific polarity you can get the induced emf to cancel or reduce to a minimal amount. Typically less then 100 mV for multiple coils.

I have found that my motor performance is optimal when this is done and the trigger is far more stable.

So seeking perfection and accuracy in the design and construction of you your motor is very important if you plan on using more then one toroid coil. I know this holds true for most pulse motors but I though it worthwhile to describe some of the reasons behind it for this motor.

Regards,

Ossie