The bearing motor

[MileHigh]

Attached is my chicken scratching drawing which is presumably a failed attempt to account for the torque generation.

It's a very bare-bones drawing.  You are looking at a rectangular piece of the axle which looks like a simple wireframe.  There is a B field "vortex" swirling around the end of the axle because of the radial current flowing through the disc of the physical bearing.

Alas, it looks like the axle gets a full 360-degree outward-pulling radial tug that cancels itself out.  That does not put any torque on the axle.

However, you can see the exploration process done in making the drawing.

[tinman]

Tinman:

Yes I was not 100% sure that the motor would only run in one direction as reflected in my choice of words.

So what is the reason for stating that it's not surprising that the motor runs the same way when you flip the polarity?  The reason is very simple.  For starters we know that the motor runs because of the Lorentz force.  That force vector is the crossproduct of the current flow with the external magnetic field.   We also know that in this case the current flow itself produces the external magnetic field.  So if you reverse the current flow, you also reverse the direction of the external magnetic field.  So it's like a double-negative and you end up with a force vector in the same direction when you flip the polarity of the applied voltage and do the cross-product.

So that means the motor spins in the same direction if you reverse the applied voltage to the terminals.  So yes the motor will run on AC, but it is certainly not an "AC motor" in the normal sense of that term.

As shown in your clip the motor will run in either direction.  It's just a question of working out the geometry to explain everything.  It's like Bill said, this is just a variation on a homopolar motor like the one people make with a standing AA cell and a paperclip.  It's also just a variation on one of those mislabelled "swirling aquarium water and bubbles" clips.

Somewhere within the bearing structure you have current flow at an angle with the external magnetic field produced by that very same current flow and that is creating a tangential force that results in torque being applied to the motor.   That is the only possible explanation and the real exercise is to figure out and show where it is happening.

MileHigh

This is all well and good MH,but a homopolar motor ia a unidirectional motor,and that direction is dependant on two thing's-current flow direction,or magnetic field orientation. This motor requires no such thing. If i apply a DC current,the motor will still spin in either direction-->what happened to the right hand ruel there ?.

[allcanadian]

@Tinman


I think I made a little progress, if we look at the rail gun circuit we see we have two rails with a rolling conductor and the conductor experiences a force dependent on the current flow/field. However in our bearing motor the races/rails are circular so the rail has no beginning or end like the rail gun. Thus the current has no preference whether it flows left or right within the bearing race/rails which explains why the motor can operate in either direction.


The AC/DC applied current was also an issue because if the current alternates or reverses direction then we would think the motor direction should as well. However AC currents may produce attractive forces in ferromagnetic materials but repulsive forces in non-ferromagnetic materials through the generation of eddy currents. The problem here, and it is always a problem conceptually is that the current/field is moving. That is the point where the current leaves the outer race is changing, the point where the current enters and leaves the ball bearing is changing and the point where the current enters the inner race is also changing.


Here's an experiment, take a ball and place it on a table then take a ruler and place it on top of the ball and move the ruler. If we move the ruler to the left the ball rolls to the left on the table but rolls to the right on the ruler not unlike our ball bearing. Knowing this we could say that if the ball bearing retained some of it's magnetism then the field generated by the present current path would repel the field in the ball bearing retained by the last current path. Thus AC or DC the ball experiences a turning force not unlike the armature in a shaded pole AC induction motor. It seems reasonable enough considering the circumstances involved.


AC

[tinman]

@Tinman


I think I made a little progress, if we look at the rail gun circuit we see we have two rails with a rolling conductor and the conductor experiences a force dependent on the current flow/field. However in our bearing motor the races/rails are circular so the rail has no beginning or end like the rail gun. Thus the current has no preference whether it flows left or right within the bearing race/rails which explains why the motor can operate in either direction.


The AC/DC applied current was also an issue because if the current alternates or reverses direction then we would think the motor direction should as well. However AC currents may produce attractive forces in ferromagnetic materials but repulsive forces in non-ferromagnetic materials through the generation of eddy currents. The problem here, and it is always a problem conceptually is that the current/field is moving. That is the point where the current leaves the outer race is changing, the point where the current enters and leaves the ball bearing is changing and the point where the current enters the inner race is also changing.


Here's an experiment, take a ball and place it on a table then take a ruler and place it on top of the ball and move the ruler. If we move the ruler to the left the ball rolls to the left on the table but rolls to the right on the ruler not unlike our ball bearing. Knowing this we could say that if the ball bearing retained some of it's magnetism then the field generated by the present current path would repel the field in the ball bearing retained by the last current path. Thus AC or DC the ball experiences a turning force not unlike the armature in a shaded pole AC induction motor. It seems reasonable enough considering the circumstances involved.


AC

First up,i to believe that magnetic forces are at work here.
But the thing that needs to be explaind is this-->how dose the initial spin direction determon the direction that the magnetic fields act to create this unidirectional force. It is very important we find out exactly what is happening here. We can look at the device as a whole,and we know that the outer race is a single turn coil,and will produce a magnetic field of one polarity. We also know that the inner race is a single turn coil,and this will produce a magnetic field opposite that of the outer race,as the current(if we look closely) is flowing in the opposite direction to the outer race,and will have the opposite voltage polarity. What i mean by opposite current flow is this-the current will be flowing into the outer race,and out of the inner race,or the opposite way round. The voltage across the bearing races will also be different,and thus 1 will be positive,and the other will be our negative. But what is it in the movement of the balls them self that determonds as to how these magnetic fields are shaped in a way to cause a force in one direction that is higher than that in the other direction?. Then there is the magnetic field along the shaft--what part dose this play?.

Looking at the first video i posted,that motor has quit a bit of torque to get that flywheel up and running so fast so quick. I have looked at the video,and i would say that the bearings i am using now in the second motor are about the same size. I pretty sure that his small transformer would not be putting out the current mine is,as his wire gauge is a lot smaller than what im using,and i have melted some of mine. My  motor has no where near the acceleration of his???. Now,my first motor wouldnt hardly maintain speed ,and yet his picks up speed no problem at all-and fast,but my first motor had an aluminum pulley,and went very slow. My second motor has the steel laminated rotor on it,and it dose pick up speed--much better than the first. The motor in the first video i posted has a larger diameter steel rotor,and that one picks up speed really fast-->i think if he let it go it would fly to pieces from RPM's.I also read one of the comments on his video,and it said-quote: and if you put a few more turns of copper plate around the outside of the bearings,it will spin even faster-the turns not touching each other of course.
I found that to be an interesting comment,as doing that would increase the strength of the magnetic field around the outer race of the bearing.

Anyway,im sure we will work it out,and i have this feeling that the outcome is going to be the reverse of that of the SEG-->although i have always believed that to be another quack job.

[Magluvin]

First up,i to believe that magnetic forces are at work here.
But the thing that needs to be explaind is this-->how dose the initial spin direction determon the direction that the magnetic fields act to create this unidirectional force.

Like I said earlier, I believe the thing has to be set into motion to provide an offset in the fields.

The way I see it, when we apply current initially, the fields are probably balanced, no motion. But while current is flowing, when the thing is put into motion, the fields in the balls most likely bend the fields produced by the balls, and this offset probably gets greater with speed. So this would explain the how of working in either direction. Spin one way, and the offset is in place for that direction of spin, and likewise the other direction.


When we apply a biasing magnet to the system, the offset is already there. The fields created by currents in the system become altered and off balance without the push start.

Maybe this can be drawn up on FEMM to see what the fields look like, around the balls and the races.  I dont know if there is a FEMM prog that shows fields developed by electrical currents.


In my vid of the magnet rolling on the foil, if it were just a solid iron disk, it probably would not move, until we moved it while current is running through it. 

So it is possible that in the videos of a AA battery with a magnet and a wire simple motors, that the magnet could be replaced by an iron disk, then give it a spin in either direction. 


Mags

Mags