A torque sensor, torque transducer or torque meter is a device for measuring and recording the torque on a rotating system, such as an engine, crankshaft, gearbox, transmission, rotor, a bicycle crank or Miniature Load Cell. Static torque is relatively simple to measure. Dynamic torque, alternatively, 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 achieve this is always to condition the shaft or a member linked to the shaft with a series of permanent magnetic domains. The magnetic characteristics of such domains will be different based on the applied torque, and thus can be measured using non-contact sensors. Such magnetoelastic torque sensors are usually employed 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 means to power the strain gauge bridge is essential, in addition to a way to get the signal from your rotating shaft. This can be accomplished using slip rings, wireless telemetry, or rotary transformers. Newer kinds of torque transducers add conditioning electronics plus an A/D converter towards the rotating shaft. Stator electronics then browse the digital signals and convert those signals to a high-level analog output signal, like /-10VDC.
A far more recent development is using SAW devices linked to the shaft and remotely interrogated. The strain on these tiny devices as the shaft flexes could be read remotely and output without resorting to attached electronics in 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.
Another way to measure Torque Sensor is by means of twist angle measurement or phase shift measurement, whereby the angle of twist caused by applied torque is measured by utilizing two angular position sensors and measuring the phase angle between them. This method can be used within the Allison T56 turboprop engine.
Finally, (as described in the abstract for US Patent 5257535), if the mechanical system involves a right angle gearbox, then your axial reaction force felt by the inputting shaft/pinion could be related to the torque experienced by the output shaft(s). The axial input stress must first be calibrated from the output torque. The input stress can be easily measured wbtbtc strain gauge measurement from the input pinion bearing housing. The output torque is easily measured employing a static torque meter.
The torque sensor can function just like a mechanical fuse and it is an important component to obtain 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 in the Multi Axis Load Cell along with its reading accuracy will likely be afflicted with the design of the driveline. The shaft becomes unstable at the critical speed of the driveline to result in torsional vibration, which can harm the torque sensor. It is required to direct the strain with an exact point for accurate torque measurement. This aspect is usually the weakest point of the sensor structure. Hence, the torque sensor is purposely created to be one in the weaker aspects of the driveline.