Torque is the rotational force that causes an object to turn, serving as one of the most fundamental parameters for measuring the output capability of rotating machinery such as electric motors, engines, gearboxes, pumps, and fans. Whether developing new electric vehicle drive motors or assessing the efficiency of an industrial water pump, precise measurement of torque and rotational speed on the shaft is essential for calculating power, evaluating energy efficiency, and analysing mechanical characteristics. This critical measurement task is undertaken by torque transducers.
Torque sensors are primarily categorised into static (reactive) and dynamic (rotary) types. In powertrain testing, dynamic torque sensors are most prevalent. They are typically connected in series between the tested machinery and the load (such as a dynamometer). Their core principle operates as follows: when torque acts upon the sensor's elastic torsion bar, the shaft body generates shear strain proportional to the magnitude of the applied torque. This strain is detected via strain gauges affixed to the shaft (arranged in a special bridge configuration to eliminate bending and axial force effects) or non-contact magnetic-electrical or optical encoders, and converted into electrical signals. Simultaneously, the sensor measures rotational speed synchronously via the encoder. Ultimately, it outputs two critical signals: the "torque value" and the "rotational speed value".
High-precision torque measurement is paramount for optimising power systems. In motor testing, it assists engineers in mapping comprehensive efficiency contour plots to identify optimal operating ranges. During engine bench testing, it serves as the basis for calibrating fuel consumption, emissions, and power curves. In energy efficiency assessments of fans and pumps, it provides the core data for determining compliance with efficiency ratings. With the advancement of electrification and intelligent technologies, higher demands are placed upon torque sensors in terms of measurement accuracy, response speed, overload protection, and intelligent diagnostic capabilities. This has established them as indispensable precision measurement sentinels within high-end equipment and green manufacturing sectors.
