OEM torque sensor Sensor Technology

The technology for our 'TorqSense' RWT310/320 Series Torque Transducers is based on the patented technology of measuring the resonant frequency change of 'Surface Acoustic Wave' (SAW) devices in a non-contact manner when strain is applied to a shaft to which the SAWs are fixed. The applied torque causes a deformation of the quartz substrate of the SAW device, which in turn causes a change in its resonant frequency. Essentially the SAWs act as 'frequency dependent' strain gauges.

The frequency signal measuring the resonant frequency is coupled via a non-contact RF rotating couple from the shaft to a fixed pick-up and it is the analysis of the difference in resonant frequencies between the two SAW devices, with electronic processing and calibration, that gives a precise indication of the torque transmitted by the shaft. SAW devices have a high immunity to magnetic fields allowing their use in motors, for example, where other analog technologies are susceptible to electronic interference and are not suitable.

The use of this patented measurement technique results in a transducer being able to sense torque bi-directional, with fast mechanical and electrical responses. As the method is non-contact it has also complete freedom from brushes or complex electronics, which are often found in traditional torque measurement systems.

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