The Dyson Digital motor is a 100,000 rpm SR motor that spins five times faster than a Formula One Engine.

In 1998, Dyson began selling the DC05 vacuum cleaner – a European-type product – to Japan. It was small, but not small enough to work for the Japanese market. As a result, the DC05 had limited success.

“It didn’t ring all the right bells,” says Alex Knox, floor care projects director for Dyson. “The Japanese market is a huge market and we wanted to develop a product that would work there and work there well.”

The Dyson engineers set a goal to have a new product developed specifically for Japan and to have it – the DC12 – ready in one year.

Building a new machine

Recognizing that size was the most critical factor, the engineers started with a cardboard box that was to fit the finished product. With the space defined, the next step was to use the same wand technology found on the DC11 canister vacuum. When not in use, the wand was able to stay in place, keeping the product small.

“Space is absolutely a premium [in Japan],” Knox says. You go around the stores in Japan and everything is minute. It was absolutely essential that we got that part right.”

With the size and wand in place, the main concern left to conquer was the motor. It had to be small enough to keep the vacuum the size of the cardboard box, and it had to be technologically advanced, a factor that Knox says is very important for appliances sold to the Japanese market.

A motor is born

The Dyson Digital motor with its impeller in an exploded view.

Over the course of six years, a team of U.K. mechanical, electrical, aeronautical, materials and software engineers had been working on a new electric motor for Dyson. The size and technological advancements would make it the perfect fit for the DC12. It would also be the first motor used in a Dyson product created by Dyson.

The Dyson 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 motor spins at more than five times faster than a Formula One engine (19,000 rpm), while typical vacuum motors run between 30,000 rpm and 40,000 rpm. It lasts twice as long as conventional motors because of several factors, including no carbon brushes or commutator.

Dyson’s motor has copper windings on the stator only, which have been overmolded to increase reliability. Conventional brushed motors – the typical motor used in vacuum cleaners – have copper windings on the stator and rotor. 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.

In addition, the fan on the Dyson Digital motor is less than half the diameter of a conventional vacuum cleaner fan. Conventional fans are typically pressed from aluminum. The fan in Dyson’s motor is injection molded from PolyEtherEtherKetone (PEEK), which is a durable engineering polymer, commonly used in the industrial sector for compressors and high-speed bearings. The fan in the Dyson Digital motor can spin at 100,000 rpm, while conventional fans are constructed to spin at about half that speed.

“The normal motor usually wears out when the brushes have worn out and there’s no carbon left,” Knox says. “With our motor, there are no brushes, so you get a long life out of the motor.” 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 Digital 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 built-in controller provides a soft start, bringing the motor to full speed in 1.5 seconds, which reduces in-rush current and prevents blown fuses.

The Dyson Digital motor incorporates turbocharger aerodynamics and aerospace materials. 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.

Getting help

The Dyson DC12 vacuum is sold exclusively in Japan, though it may be available to more markets in the future.

If anything goes wrong with the Dyson Digital motor – or any other part of the vacuum for that matter – 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.

The DC12 went on the market in June 2004. 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. Knox says that potentially all future Dyson vacuums will utilize this motor. He also says that the DC12 is catching the interest of other markets, and the company may decide to sell it in other countries.

So will a smaller motor mean that all Dyson vacuums will also move toward a reduction in size? Knox says probably not. “The smaller motor does give us the opportunity to do things smaller, lighter and get more power out of it. Having a small motor allows us to have a small machine that works like a big machine. But, the European market would want to keep the reasonable-sized products. I think we will always do something in that [European] type of size. It will just be lighter and more powerful. It opens up opportunities.”