A torque sensor, torque transducer or torque meter is a device for measuring and recording the torque on a rotating system, like an engine, crankshaft, gearbox, transmission, rotor, a bicycle crank or Compression Load Cell. Static torque is relatively very easy to measure. Dynamic torque, on the other hand, is not easy to measure, because it generally requires transfer of some effect (electric, hydraulic or magnetic) from the shaft being measured to a static system.
One way to accomplish this is always to condition the shaft or even a member connected to the shaft with several permanent magnetic domains. The magnetic characteristics of these domains will vary in accordance with the applied torque, and thus may be measured using non-contact sensors. Such magnetoelastic torque sensors are generally used for in-vehicle applications on racecars, automobiles, aircraft, and hovercraft.
Commonly, torque sensors or torque transducers use strain gauges placed on a rotating shaft or axle. With this method, a method to power the strain gauge bridge is necessary, as well as a means to have the signal from the rotating shaft. This could be accomplished using slip rings, wireless telemetry, or rotary transformers. Newer types of torque transducers add conditioning electronics as well as an A/D converter to the rotating shaft. Stator electronics then browse the digital signals and convert those signals to your high-level analog output signal, such as /-10VDC.
A much more recent development is the use of SAW devices attached to the shaft and remotely interrogated. The stress on these tiny devices since the shaft flexes may be read remotely and output without the need for attached electronics around the shaft. The probable first utilization in volume will be in the automotive field as, of May 2009, Schott announced it features a SAW sensor package viable for in vehicle uses.
A different way to measure Torque Sensor is by way of twist angle measurement or phase shift measurement, whereby the angle of twist resulting from applied torque is measured by making use of two angular position sensors and measuring the phase angle between the two. This procedure is used in the Allison T56 turboprop engine.
Finally, (as described within the abstract for US Patent 5257535), if the mechanical system involves a right angle gearbox, then this axial reaction force felt by the inputting shaft/pinion may be linked to the torque gone through by the output shaft(s). The axial input stress must first be calibrated against the output torque. The input stress can be simply measured wbtbtc strain gauge measurement in the input pinion bearing housing. The output torque is easily measured employing a static torque meter.
The torque sensor can function like a mechanical fuse and is also a key component to have accurate measurements. However, improper installing of the torque sensor can damage the device permanently, costing money and time. Hence, the torque sensor has to be properly installed to make sure better performance and longevity.
The performance and longevity of the Multi Axis Load Cell as well as its reading accuracy is going to be affected by the design in the driveline. The shaft becomes unstable at the critical speed of the driveline to result in torsional vibration, which can damage the torque sensor. It is necessary to direct the strain with an exact point for accurate torque measurement. This point is usually the weakest reason for the sensor structure. Hence, the torque sensor is purposely created to be one from the weaker aspects of the driveline.