All-in-one torque sensor targets OEMs

Sensor Technology, the British company that pioneered a novel torque-sensing technology based on SAW (surface acoustic wave) devices, has launched a lower-cost version which, it believes, could open up the OEM market. Unlike earlier versions which were hand-built and required separate electronics, the new version has the electronics built in and has been designed for volume production. This has brought prices below £1,000, with the potential for even lower costs as volumes build up.

Unlike traditional slip-ring transducers, the TorqSense sensors (above) provide a simple non-contact technology for measuring the power in drive shafts and other rotating elements. Torsion is sensed by a pair of SAW strain gauges bonded to a shaft at right-angles to each other. One senses compression and the other tension, and this information is transmitted via a radio frequency couple to the decoding electronics which generates outputs for torque, speed, power and angle.

Sensor Technology has been building and selling sensors based on the technology for more than five years. "With the concept now proven, in the real world of factory machines and process plants," says director Bryan Lonsdale, "we have integrated the electronics and the pickup into a single unit and designed everything for serial manufacture".

The sensors incorporate diagnostics, torque averaging and peak torque sampling and storage functions. There are two versions, one (model RWT210) provides analogue outputs, while the other (RWT 320) adds digital signals. The sensors, which can operate at speeds of up to 30,000 rpm, initially offer full-scale deflections of 1-20Nm. This will be extended to 10,000Nm by the end of 2004.

Sensor Technology hopes to sell around 500,000 of the new sensors in the first year. The company is planning to move to larger premises to accommodate the increased workload. Its long-term aim it to integrate the electronics onto a single chip which would allow it to compete in mass markets such as automotive power steering, where unit prices of well below $50 are essential.