Hilden-Brand Magnet Motor

[hartiberlin]

Hi Rob,
you have to scrap the last "c" shaped core piece form your stator !
Otherwise you just shortout the flux with which you attract the rotor !

[MeggerMan]

Hi Stefan,
Yes, I realised this after a bit of thinking.
I have another idea to interleave the pole faces, with enough gap to prevent the flux bridging it without the rotor in proximity.
This is to enable the rotor to make the circuit for a greater rotation but this cannot be simulated in 2D it needs a 3D model.

Or I could just bring the pole faces very close together, it should end up that the force will be active for half the width of the rotor face minus the pole gap, it will drag after the centre point and the coil needs to be turned off slightly before centre point.

I will do some more Femm simulations and post the results.  In Femm it is possible to work out the force exerted on an object but I have not yet figured this out yet.

Regards

Rob

[hartiberlin]

Hi Rob, the good part ofthe Hilden-Brandt motor is,
that it only needs very short pulses, when the rotor
is in the proximity of the stators to be attracted and
the rest of the time the coils can be off and the magnet
flux is shortouted via the cylinder ironcore around the magnet.
So it is a very efficient design to just use very low input power
and attract strongly a rotor, when the coils are energized.

[MeggerMan]

Hi Stefan,
I also suspect that the initial current needs to be quite high and can tail off as the rotor reaches the centre point, with the pulse going off there will be a back emf as the field re-routes through the core steel surrounding the magnet. I'm not sure if this can be salvaged.

The power required for the switch is milliamps (about 10mA), provided the rotor is very very close to the stator. Larger gap = larger current.
Rather than use a cylinder magnet, I would be tempted to go for a square cross section magnet for the simple reason that it is easier to cut the laminations.

The laminations need to be step lapped for max flux, so I suppose you could build the feedback core from strips that a lapped into the main limbs.
Its like making a tight fitting jigsaw and a real hard task in itself.

Regards

Rob

[jake]

Hi Rob, the good part ofthe Hilden-Brandt motor is,
that it only needs very short pulses, when the rotor
is in the proximity of the stators to be attracted and
the rest of the time the coils can be off and the magnet
flux is shortouted via the cylinder ironcore around the magnet.
So it is a very efficient design to just use very low input power
and attract strongly a rotor, when the coils are energized.

I respectfully disagree with this analysis.

You are not utilizing the flux at all most of the time.  You are short circuiting the flux to a completely useless path most of the time.  The magnets might as well not be there when the power is off.

Look at the design in the Flynn paper.  It has all of the advantages of the Hildenbrand "valve", and it utilizes the permanent magnet flux all of the time.

I believe a better arrangement would have the coil releasing the magnet momentarily, so that the pm flux would be "working" most of the time, not short circuited where it can do no useful work in the motor.

Note that the Flynn motor "locks" with the power off - full torque with no power applied - the magnets are shorted through the rotor, holding it at all times until power is applied momentarily to the coils to advance the rotor.  I believe this design makes much better use of the permanent magnets.  You get torque when the power is off, and torque when the power is on - using the pm flux 100% of the time, not just when the power is on.

The Flynn motor does better than just turning the flux on and off.  It leaves the flux on 100% of the time, and directs the flux to where it is needed in the circuit to apply force where it is needed to make the motor rotate.  This gives complete utilization of the available flux at all times.  What could be better?  Certainly shorting out the flux to a non-working path can't be better than using the flux at all times in a working path.

Please don't take this as an attack on the valve.  It is a very creative and noteworthy design.  I just think it should be re-arranged in a way that uses part of the rotor as the shorting path, such as Flynn does.  There has to be a better way to arrange the circuit such that the flux is being used when it is in the off position.  Another factor is that the valve apparently allows the use of permanent magnets in the rotor.  I don't know that any Flynn designs can do this.  This factor may be a great advantage to the valve that is not obvious.

I believe that the best motors will be ones that are locked with no power, and rotate by momentarily releasing certain magnets - similar to what Flynn is doing.  This it just a "gut feeling" - no proof to offer.