Dyson develops high efficiency motor for vacuum cleanersRichard BallEngineers at Dyson have developed a 100,000rpm motor for the firm's vacuum cleaners that is over 80 per cent efficient.
The X020 is a switched reluctance (SR) design with a compressor fan capable of moving 30 litres of air per second while dropping 30kPa (4.3psi) pressure.
"We try to tune and get the most out of the products," said Matthew Childe, project manager on the X020. "We needed performance over and above that of a standard motor."
Dyson used finite element analysis (FEA) and computational fluid dynamics to design the rotor and impeller assembly which is made from steel and polymer. This was critical, as the edges of the rotor exceed speeds of 600mph within 0.3mm of the coils. The rotating assembly weighs just 90g.
"We needed to do an incredible amount of FEA to make sure it doesn't fly apart," said Childe. A one gram speck of dust on the impeller would have the same impact as a 200kg mass, he said.
Although it runs up to three times faster than an AC series motor, at 1kg the unit weighs 25 per cent less.
To reduce noise, always a problem in SR motors, the team designed soft mountings for the rotor, a significant achievement considering the speeds and tolerances involved. This technique is covered by one of several patents applied for in relation to the motor.
Lifetime is suited to domestic appliances, said Childe: "An SR motor has only got one wearable part - the bearings - so the lifetime is related to the bearings." A 1,000 hour life is promised, or around seven to ten years of average use.
For control the firm uses a standard 16-bit microcontroller with on-board EPROM to store usage data and the motor's behaviour. This data can be downloaded back to Dyson via a buzzer and a standard telephone handset.