Mini-motor runs with fewer parts

Full-scale production of a low-cost piezoelectric motor, which needs almost no moving parts, has begun in Germany.

Designed by Elliptec, a technology start-up company owned by Siemens, the motor willinitially be made for children’s train sets and around 10,000 are to be produced in the next few weeks.

The technology could have a far wider range of applications in any electrical equipment that requires miniature motors, such as CD drives, car door locks, printers and moveable slats in air-conditioning systems.

The Elliptec motor exploits a piezoelectric element to generate high-speed vibrations of up to 100,000Hz. When the motor’s main surface is placed in contact with another object and held in place with a simple spring, the vibrations are transferred into motion – for example moving a rod backwards and forwards or turning a wheel.

The motor does not require a gearbox since the speed of vibration can be controlled via its electric signal input. its developers claim that in terms of ‘quality’ of motion and precision control, it offers similar levels to expensive and complex stepper motors.

Other companies make piezoelectric motors, but they are not currently in wide and varied use due to cost, which is around £100 per unit. Elliptec’s chief executive officer, Bjoern Magnussen, claims his technology is revolutionary due to its far lower price, at around e1 (60p) per unit comparable to the cost of a less-capable traditional electromagnetic DC motor. ‘It’s like when you want to buy a car, and someone says they can sell you a helicopter at the same price,’ said Magnussen.

He said the key to Elliptec’s technology had been developing a cheaper piezoelectric element and designing the rest of the motor, including manufacturing processes, around it.

The motor can also operate at low voltages of 3-6V (other piezoelectric motors require higher voltages), and Elliptec claims it is 92 per cent lighter and 80 per cent smaller than a conventional DC motor. It can produce linear motion of around 300mm/sec with 1n of force, enough to lift about 84g.

In the future, said Magnussen, miniature piezoelectric motors could drive anything in which a conventional motor is currently used, though he would rather allow the product to develop further before it is marketed for medical applications.

‘We targeted the toy industry because of its quick design cycles,’ said Magnussen, ‘though other customers are in the pipeline.’

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