Sensor Technology has released a new range of non-contact torque sensors based on a full four-element strain gauge bridge design, complementing its existing non-contact sensors that use surface acoustic wave detection.
Designated the TorqSense SGR510/520 series, the new units provide a 250% over-range reading capacity, enabling sudden spikes in torque to be measured and recorded accurately. The design also compensates for any extraneous forces, including bending moments, unwittingly applied to the sensor, increases sensitivity and has an extensive temperature tolerance.
The bridge is four strain gauges fixed onto the shaft that is to be monitored in a square formation set at 45 degrees to the axis of rotation. Therefore, when torque is applied to the shaft, two gauges are pulled into tension, and two go into compression.
A rotor mounted ultra-miniature microcontroller, powered via an inductive coil, measures the differential values in every strain gauge and transmits them back to the stator digitally through the same coil. The series transducers then use state of the art strain gauge signal conditioning techniques to provide a high bandwidth, low-cost torque measuring solution with high over range and overload capabilities.
“This design gives the TorqSense SGR510/520 several significant advantages over conventional torque sensors,” says Mark Ingham of Sensor Technology. “Firstly, it eliminates the sort of noise pickup and signal corruption associated with slip ring and other analogue methods of transferring torque data from rotor to stator.”
“For ease of use there is a built-in test function,” says Mark, who summarises the new TorqSense SGR510/520 with: “Most torque sensors require the use of slip rings to transfer torque readings from the rotating shaft to the static readout. These are noisy in use, slow and fiddly to set up and, as wearing parts, are not always reliable.
“Our TorqSense ranges operate without slip rings, using non-contact signal transfer instead, so these problems are designed out at a fundamental level. The new SGR510/520 series will be suitable for torque measuring, testing, feedback control of drive mechanisms and process control applications."