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23 May 2002

Tiny motor targets snug applications

Dortmund, Germany - A tiny, near-silent piezoelectric motor about the size of a penny and which has the potential for being used in scores of applications has been unveiled by a Siemens startup business unit.

Siemens' Elliptec motor, compared to a match. Elliptec AG Photo.

The Elliptec motors from Elliptec AG, a Siemens Technology-To-Business Center LLP start-up, could soon replace millions of electromagnetic minis currently in use in a wide range of applications. Large-scale production and shipment of the motors is expected this summer, said Bjoern Magnussen, president and CEO of Elliptec AG.

"We see many applications in the medical and industrial automaton fields, in printers, in computer equipment as well as in automobiles and in homes," Magnussen said. The company began shipping engineering samples to product designers at the end of January and has already received a substantial number of orders.

The Elliptec motor uses a piezoelectric element to generate high-speed ultrasonic vibrations up to 100,000 times per second, which, in turn, can spin a wheel or move a rod. At one-twelfth the weight, and one-fifth the size of standard electromagnetic minis, the Elliptec require only 3-6 volts to operate and have only three parts - piezoelectric element, mounting spring and vibration frame. Patents are pending on the technology, Magnussen said.

The Elliptec motor does not need a gearbox, as is required in direct current (DC) motors, to control its speed. Rather, it can produce slow motion directly via an electric control signal used to set the speed. Magnussen said the Elliptec's motion control is comparable, in terms of quality, to more expensive stepper motors.

Elliptec officials believe the new motor is a cost effective alternative to conventional DC mini motors in applications where it is connected to an electronic chip or when bi-directional motion is needed, since it requires less than one-third of the electronic components. They see the motor having considerable advantages in applications where there is little room, such as toys, and where slow or very well-controlled motion is required.

"As production volumes increase over the next few years, we expect prices to drop significantly and go below the one dollar level," said Magnussen.

"The technology has tremendous potential in applications requiring very small motors used to provide motion in toys, open and close air conditioning vents, or move CD ROM trays in and out," he suggested. Initial motor models, he added, will be used in applications where the size, weight, or noise of conventional mini motors can pose problems.

While the basic technology behind the Elliptec dates back more than 35 years, previous piezoelectric motors generally required very high voltages to operate, making them expensive. Compared to present piezoelectric motors, the Elliptec does not require extremely critical tolerances, the construction is simpler and does not need expensive material, and the motor is substantially cheaper.

The motor principally produces linear motion at speeds between 0 and 12 inch/second and forces up to 1 Newton (the force needed to lift 3 ounces). The force can be increased, if several motors are used together.

To produce rotational motion, the motor generates linear motion at the rim of a wheel. The resulting rpm value and the torque depend on the wheel's diameter. While it's possible to vary the speed of electric motors to a limited extent - by changing the voltage - using signal generation, a piezoelectric motor can be slowed down (or speeded up) to the desired speed.

Elliptec AG, based in Dortmund, Germany, was formed as an independent start-up company in 2001 following development of a prototype piezoelectric motor by a Siemens Technology-To-Business Center team. The technology upon which the prototype was based was first developed by Siemens Corporate Technology in Munich, Germany.