Sensor Technology Ltd. - PRODUCT NEWS

New range of TORQSENSE Rotary Torque Transducers. Sensor Technology Ltd announces that, after more than 10 years of development, a range of Rayleigh Wave TORQSENSE (RWT) transducers is now available. Their experience of working with this relatively simple patented technology also means that it can now be embedded into OEM products. A family of TORQSENSE transducers is now available in 7 sizes measuring torque from 100mNm up to 10,000 Nm at Full Scale Deflection with smaller ranges having speeds up to 30,000 rpm. The advantages for using SAW devices in torque transducers are: Cost sensitive Minimum length of shaft Low inertia Non contact between housing and shaft Simplicity High Bandwidth Signal immunity Non speed dependent Rotary torque has historically been difficult and expensive to measure. The patented method uses SAW devices as 'frequency dependent' strain gauges to measure the change in resonant frequency caused by the applied shaft strain. By using a frequency-based device, the signal bandwidth is increased, and the problem of electronic interference common with other analogue based technologies is eliminated. TORQSENSE transducers have a minimum length and relatively high stiffness of shaft, low inertia, no physical contact between shaft and housing, wide bandwidth, high resolution and accuracy, and excellent noise immunity. TORQSENSE technology is suitable for utilization in OEM applications where knowledge of torque is critical. In a TORQSENSE transducer, surface waves are produced by passing a high frequency voltage across the terminal of two interleaved comb-shaped arrays that are layered onto one end of piezoelectric substrate. A similar 'receiving' terminal, at the other end of the transducer, converts the wave back in to an electric signal. The frequency of the wave generated is dependant on the spacing of the 'teeth' in the comb array and as the direction of the wave propagation is at right angles to the teeth, any change in its length alters the spacing of the teeth and hence the operating frequency. To measure torque in a shaft, two SAW transducers are bonded at 45 degrees to the shaft's axis and connected in a 'half bridge' configuration, so that when the shaft is strained, the difference in frequency output between the two SAWS relates to the applied torque. TORQSENSE transducers require no physical connection to the shaft's housing. Instead, the signals are transmitted via a coupling device. OEM applications for TORQSENSE include automotive, manufacturing machines, condition monitoring, tightening procedures and monitoring and control of viscosity during mixing processes. __________________________________________________ For more information, please contact :- Sensor Technology Ltd. Tel: +44(0)1295 730746 Fax: +44(0)1295 738966 Email: Website: June 2002

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