Hi there Jetijs / All.

Well here is another video of my version. And for the record, please note that I am not by any stretch some expert in motor building or electronics. Yes I build some stuff , read some stuff and think to know some stuff. But don't let any (false) idea your talking to some know it all professor stop you from commenting whatever it is. Since I do not know it all, not even much that is. So together we might some day know it all. But I appreciate the kind words.
Anyway here it is. (Nice acceleration he?)
http://www.krystyna.nl/Machine/MotorRun001.wmv

Kind regards,
Steven

Steven,
Great video!
Couldn't it be that your stator core poles are too close together? Maybe this doesn't allow the motor to "breathe" between pulses, just as Peter mentioned.
Just a thought

Yes this could very well be. Especially for the rotor since that solid steel will not loose it magnetic alignment very fast - to say the least. But the amp draw is (in my opinion) due to the voltage ruling over the ohmic resistance of the coil.

Side note: You know these expensive Dyson vacuum cleansers? Well some types have switched reluctance motors in them.
MOTORS, FANS & BLOWERS: New Market: New Motor - Archives - Appliance Design

Regards,
Steven

In fact the Dyson motor is very much like yours:
See attached picture.

Attached Images

	RelMotor.jpg (21.2 KB, 56 views)
	img_digital_motor.jpg (19.4 KB, 52 views)

Here's a bigger picture:
http://www.atv-semapp.dk/arr2006/061...0%5B1%5D_r.jpg
The stator/rotor pieces look indeed like my motor. Such a motor would be the perfect for what we need, but unfortunately we do not know how small the air gap is between stator and rotor. If it is too big, than there is no point in buying them for our needs.

Jetijs et al,

Excellent recovery on your bolt holes; beautiful work. Would vibration damping (thin rubber washer) allow the bolt heads to distribute the stresses between the Acrylic to metal intersection?

Note: an uneven shoulder cut of the bolt heads, may produce stress cracking of the assembly (path of least resistance) during operation.

Dyson motor:

Is that a set of (4) coils behind the Stator (left), on the Dyson motor ?

I'd also have to say the Tesla Turbine Pump would be a much better match for the Dyson.

I'll make some phone calls in the morning and try to obtain "Build Quality /Tolerances) for the Dyson. They may even have a catalog of replacement parts

Best regards,

- Schpankme

Steven,

Thanks for posting the films of your motor. I'm glad to see you working on it again.

I haven't commented on it so far, because there really isn't enough information presented to evaluate. It would help to know what the full schematic of the test circuit is, as well as the switch timing. Your film emphasizes a relationship between input current and rotor speed, but this is not enough to say anything about WHY it might be happening.

In general, I agree with your statement that the current limit is set by the ohmic resistance of your coil. This is true of ALL motors, including the ones we are building here.

If you recall from my latest film on YouTube, the motor performed the worst when the energy of the coil collapse was just shorted out with a diode. Under these circuit conditions, the motor turned the slowest and drew the most current. You may also recall that the speed went up and the input current went down when the recovered energy was used to power a light bulb. So, what you do with the inductive collapse affects the motor performance quite a bit.

So, I'd be glad to comment when I see:

1) the complete schematic of the circuit you are testing
2) a complete explanation of your timing sequence that includes the number of degrees of rotation defined by your stator pole faces and the ON time/OFF time positions of your two power coils, and
3) an explanation of how your circuit is handling the energy of the inductive collapse.

Peter

Schpankme,

Checking on the tolerances for the Dyson Motor is a great idea. Seeing if it available as a replacement part is an even better idea!

One thing about this motor that I am still not certain of is the exact shape of the rotor. The exploded diagram obscures the rotor image so I can't see it completely. The motor Jetijs is building will not START in all positions, but the Dyson Motor probably does, so there must be some differences.

Thanks for following up on this and letting us know what you find.

Peter

Dyson DC12 Digital motor

The Dyson DC12 Digital motor, code named X020, is a 100,000 rpm switched reluctance (SR) motor, meaning that the reluctance (magnetic resistance) is switched between the pole of the stator to create torque through the rotor, forcing it to spin. The DC12 motor was designed 1998, for the Japanese Market.

Dyson’s motor has copper windings on the stator only, which have been over-molded to increase reliability. Because of the windings being on the stationary part only, the SR motor is more reliable than conventional motors as they have exposed windings on the rotating shaft assembly that are prone to damage.

The motor has a working life of more than 1,000 hours – an important fact considering that most vacuum cleaner motors, typically lasting 600 hours, wear out long before the rest of the product. A longer-lasting motor means a longer-lasting vacuum.

Weighing 1,000 g (about 2.2 lbs.), compared to 1,300 g (almost 3 lbs.) for a standard domestic appliance motor, the Dyson DC12 Digital motor has good power-to-weight ratio. Also, the engineers were able to reduce the rotor weight by 50 percent, making the entire rotating assembly weighing less than 100 g (0.2 lbs.).

The Dyson Digital motor has a built-in controller, which provides a soft start, bringing the motor to full speed in 1.5 seconds, which reduces in-rush current and prevents blown fuses.

The impeller blades curve continuously, in all three dimensions, with almost no straight 2D section on the blades.

The square-core motor makes up to 1,666 revolutions every second. At this speed, the built-in control system pulses the motor with energy four times per revolution, which translates to more than 400,000 signals, decisions and power pulses every minute.

It's important for such a high-speed motor to be precisely balanced to avoid excessive vibration. A Dyson engineer explains, “The rotor does spin very fast, above its natural frequency. Every rotor is individually balanced to reduce vibration and improve motor reliability.”

Reducing vibration and improving motor reliability also comes into play where noise level is concerned. SR motors are typically louder than other types of motors, and Dyson engineers kept the Dyson Digital at an acceptable noise level by carefully balancing the components in production and ensuring that the motor system is isolated from internal vibrations.

If anything goes wrong with the Dyson Digital motor – a 128 byte memory chip will help to run diagnostic tests and enhance performance.

The embedded software keeps track of the motor’s “DNA,” including usage, general operating information and even the vacuum’s build date.

After phoning the Dyson help line, a user would hold the phone to a small speaker at the base of the machine and press the “On” button, which has a graphic of a phone on it. Typical fax sounds are immediately heard, which is the transferring of information to a Dyson customer service representative.

In addition, the software helps to manage the motor, like an engine management system in a car, keeping the motor safe and efficient.

Though the Dyson Digital motor is currently only available in the DC12, which is sold exclusively to Japan, the motor and the machine will be showing up in other machines and other markets, respectively.

Ref: Karen Buscemi, 2005

- Schpankme

Dyson DC07 DC14 Upright Vacuum Cleaner Complete Motor - (eBay.ca item 190184386802 end time 15-Feb-08 11:43:18 EST)


$45.00

Yes it is not the DC 12, but hey I sent an email to this guy to find out if he sells the DC12 motor.

I searched all around googe for this DC12, all I could find was only the vacuum cleaner with this motor inside, but no spare parts. The cost for this vacuum cleaner was about 500-600$ and I found them only in some Japanese stores. Isn't it suspicious that they announced this mode in 2004 but now, four years later, this model still seems so rare.

Dear marthale,

Dyson Dealers are the only place to find the DC12 Motor. The factory has not opened the market to distributors and wholesalers. Thanks Marty

This what the seller on Ebay sent me.

Hi all. Today I received back my stator core with the inner surface machined smooth. Looks very nice.





Now I am waiting for my shaft. I gave them my drawings today, it can take up to a week till they make it, because I am not the only customer
Thanks,
Jetijs

Nicely done Jetijs.

BTW - did you have any problems machining plexiglas?

Hi lighty,
Machining plexiglass is easy and fast as long as I don't subject the machined pieces to any kind of solvents, oils or other chemicals, that makes the material to crack on the weakest points. I had some problems using epoxy resin, that cured too fast and exposed the plexiglass to pressure and heat, making cracks. This last design is machined so that I do not need any kind of glues or other chemicals, so the material should hold fine. My cnc machine has very high RPMs, the lowest I can get are about 9000RPM, of course this is too much for any kind of plastic, because at these speeds it would just melt. So I need to use a liquid cooling system, to cool the endmill bit and flush away any chips.
Thanks,
Jetijs

Hello Jetijs,

What method was used to smooth (finish) the core inner surfaces ?

- Schpankme

They stacked the stator core in a lathe and used a very sharp cutting tool with small passes, a little bit deeper each time till the surface was smooth
Jetijs

Air jet dries hands at 400mph 16/11/2006

Dyson’s new product – a hand dryer that claims to be more hygienic and efficient than its rivals – could be the first in a series of technologies to use its digital motor. Lou Reade reports

James Dyson’s latest concern is not his school for engineers, but something much smaller: your hands. Just as he re-thought the way that vacuum cleaners work, so his company has now devised a hand dryer that works differently to conventional products.
Instead of using hot air to evaporate water from your hands, the Airblade uses a high-speed ‘sheet’ of unheated air to force excess water off the surface – rather like air jets in a car wash. Dyson claims it is more hygienic, more energy-efficient and far faster than existing products. The company spent three years and £10m on the development.
“It will dry your hands in 10 seconds,” says Dyson design engineer Paul Finn-Kelcey, who worked on the Airblade.
The technology at the heart of the dryer is Dyson’s digital motor, which spins at 100,000rpm. To date, the motor has only been used in the DC12 vacuum cleaner, which is sold in Japan.
The motor generates enough pressure to force air through a 0.3mm slot, which runs for the length of the dryer. There are actually two slots: one is relatively straight and dries the palm side of the hand; the other is bent into the shape of a ‘3’ and dries the back of the hands and knuckles.
“The aperture in the middle of this one is about 0.7mm,” he says. “It’s because you need more air to dry that part of the hand.”
The twin-headed vent that delivers air to the slots is made from glass-filled polypropylene, while the slots themselves are made from a composite material.
Dyson says that the Airblade overcomes all the problems that it identified with existing dryers – they are unhygienic, take too long to dry hands and are expensive to run.
First, it ensures that incoming air – which will be blown across freshly washed hands – is clean by drawing it through a Hepa filter.
The method of recycling water is also ingenious. Water that has been removed from the hands is caught and fed through an iodine filter. This clean water then drips onto a piezoelectric crystal about the size of a 10p piece. This fast-vibrating element acts as a nebuliser, converting the water into a puff of vapour which is blown back into the atmosphere.
All components are contained in a die-cast aluminium housing. Internal and external parts have an anti-microbial coating to maintain hygiene.
The Airblade removes excess moisture from the hands – enough for them to feel ‘dry’ – in 10 seconds, around a quarter of the time that it takes a conventional dryer to do the same job. This is the first source of energy saving, says Dyson. The other is that the Dyson motor is only 160W, compared with 240W for a conventional dryer.
“The energy saving is a combination of these two factors,” says Finn-Kelcey.
Inevitably, a patent wrangle has reared its ugly head. Mitsubishi of Japan has had a product called the Jet Towel on the market for a number of years, and recently launched the product in the US. Mitsubishi has accused Dyson of copying its design. Dyson has responded by saying its design is radically different and more effective – and intends to challenge Mitsubishi’s claimed drying time of three to six seconds.

Series start
The Airblade is likely to be the first in a series of products that rely on the Dyson motor.
Since launching the DC12 vacuum cleaner in Japan over two years ago, Dyson engineers have continued to refine the motor.
“We’re constantly trying to improve it,” says Finn-Kelcey. “The electric control system is being improved and we’re also trying to make the circuit board smaller.”
However, he says there are “more steps to go” before the motor can be put into the next product.
“Within two years, you will see lots of other products that use the Dyson digital motor,” he says. “We have more engineers working on the next generation of this motor than on any single product.”


Motoring on
Conventional motors use brushes, fixed magnets and commutators, but these are absent from the Dyson motor.
The company says that this makes it more long-lasting – giving it a typical lifetime of 1500 hours or more. Its lighter weight means it can rotate at 100,000rpm.
“A conventional motor might be able to manage 40,000rpm,” says Finn-Kelcey.
According to Dyson engineers, the motor is likely to feature heavily in future Dyson products, becoming almost a core technology for various products.
The motor’s embedded software gives it diagnostic abilities, allowing it to manage energy efficiently and safely. Problems can be communicated back to a call centre via the internet.
“We are focusing heavily on the next generation of the motor,” says Finn-Kelcey
Dyson is keeping very quiet about specific applications, but it seems likely that an improved version of its motor will be a crucial part of emerging products.
“If we can make the motor smaller and more efficient, this would make smaller products more feasible,” he says.


Author
Tom Shelley