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Dyson fan: why it is a 'novel invention'

When Dyson launched its bladeless fan, The Air Multiplier, it received plaudits in Britain and America. However documents unearthed at the Intellectual Property Office cast doubt over the novelty of the invention. Was it first developed 30 years ago in Japan? Here, Peter Gammack, Dyson's design director, explains why it was not.

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Left: Dyson patent (2009) and right: Tokyo Shibaura patent (1981)
Left: Dyson patent (2009) and right: Tokyo Shibaura patent (1981) Credit: Photo: UK INTELLECTUAL PROPERTY OFFICE

I have been at Dyson for twenty years and was heavily involved in the Air Multiplier fan’s development. I would like to clarify some confusion over how our fan works and how it is different from the Japanese disclosure and other industrial devices.

In our fan:

1. A mixed-flow impeller draws in air which is then pushed up into the loop.

2. The air exits the aperture at high velocity and creates an area of low pressure that draws in air from behind the fan.

3. The fast-moving air follows the precisely designed 16° aerofoil-shaped ramp (the Coanda effect) which creates a further area of low pressure, drawing in even more air.

4. As the air jet leaves the front of the loop, more air is entrained due to ‘viscous shearing’, amplifying the initial airflow even further.

The Japanese design does not make use of the Coanda effect as ours does. It simply uses a motor in the base to force air out of the ring.

The industrial devices work from compressed air lines, and are not suited to the pressures and flow rates we are using for a desk fan.

Anyone that works in design or engineering will appreciate the incremental changes that occur when developing something new. An engineering principle applied in a different way still takes a huge amount of time, effort and development to get right. The reason why no other bladeless fan has come to market is because it’s very difficult to get right – I can vouch for that.