A torque sensor, torque transducer or torque meter is actually a device for computing and recording the torque on a rotating system, including an engine, crankshaft, gearbox, transmission, rotor, a bicycle crank or torque transducer. Static torque is comparatively very easy to measure. Dynamic torque, on the other hand, is difficult to measure, because it generally requires transfer of some effect (electric, hydraulic or magnetic) through the shaft being measured to a static system.
One method to accomplish this would be to condition the shaft or perhaps a member attached to the shaft with a number of permanent magnetic domains. The magnetic characteristics of these domains will be different based on the applied torque, and thus could be measured using non-contact sensors. Such magnetoelastic torque sensors are usually used for in-vehicle applications on racecars, automobiles, aircraft, and hovercraft.
Commonly, torque sensors or torque transducers use strain gauges put on a rotating shaft or axle. Using this method, a means to power the strain gauge bridge is necessary, in addition to a means to have the signal from your rotating shaft. This is often accomplished using slip rings, wireless telemetry, or rotary transformers. Newer kinds of torque transducers add conditioning electronics and an A/D converter towards the rotating shaft. Stator electronics then look at the digital signals and convert those signals to some high-level analog output signal, like /-10VDC.
A much more recent development is using SAW devices attached to the shaft and remotely interrogated. The stress on these tiny devices because the shaft flexes could be read remotely and output without making use of attached electronics on the shaft. The probable first use within volume will be in the automotive field as, of May 2009, Schott announced it has a SAW sensor package viable for in vehicle uses.
An additional way to multi axis load cell is by means of twist angle measurement or phase shift measurement, whereby the angle of twist as a result of applied torque is measured by making use of two angular position sensors and measuring the phase angle between the two. This method can be used within the Allison T56 turboprop engine.
Finally, (as described in the abstract for US Patent 5257535), in the event the mechanical system involves a right angle gearbox, then this axial reaction force experienced by the inputting shaft/pinion can be associated with the torque experienced by the output shaft(s). The axial input stress must first be calibrated up against the output torque. The input stress can be nanzqz measured via strain gauge measurement in the input pinion bearing housing. The output torque is readily measured employing a static torque meter.
The torque sensor can function such as a mechanical fuse and is a vital component to obtain accurate measurements. However, improper setting up the torque sensor can damage the device permanently, costing money and time. Hence, the torque sensor must be properly installed to make sure better performance and longevity.
The performance and longevity from the miniature load cell and its reading accuracy will likely be impacted by the design of the driveline. The shaft becomes unstable in the critical speed of the driveline and results in torsional vibration, which can damage the torque sensor. It is essential to direct the strain for 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 of many weaker components of the driveline.