Air jet dries hands at 400mph

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.