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 rotary torque sensor. Static torque is fairly simple to measure. Dynamic torque, on the contrary, is difficult to measure, as it generally requires transfer of some impact (electric, hydraulic or magnetic) from the shaft being measured to a static system.
One way to accomplish this is to condition the shaft or perhaps a member connected to the shaft with several permanent magnetic domains. The magnetic characteristics of those domains can vary according to the applied torque, and so may be measured using non-contact sensors. Such magnetoelastic torque sensors are usually utilized for in-vehicle applications on racecars, automobiles, aircraft, and hovercraft.
Commonly, torque sensors or torque transducers use strain gauges applied to a rotating shaft or axle. With this method, a method to power the strain gauge bridge is essential, 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 plus 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, such as /-10VDC.
A far more recent development is the usage of SAW devices attached to the shaft and remotely interrogated. The force on these tiny devices since the shaft flexes can be read remotely and output without resorting to attached electronics on the shaft. The probable first use within volume will be in the automotive field as, of May 2009, Schott announced it possesses a SAW sensor package viable for in vehicle uses.
A different way to multi axis load cell is by means of twist angle measurement or phase shift measurement, whereby the angle of twist caused by applied torque is measured by making use of two angular position sensors and measuring the phase angle between the two. This technique can be used inside the Allison T56 turboprop engine.
Finally, (as described inside the abstract for US Patent 5257535), if the mechanical system involves the right angle gearbox, then this axial reaction force experienced by the inputting shaft/pinion can be related to the torque gone through by the output shaft(s). The axial input stress must first be calibrated up against the output torque. The input stress may be nanzqz measured via strain gauge measurement from the input pinion bearing housing. The output torque is definitely measured utilizing a static torque meter.
The torque sensor can function such as a mechanical fuse and is also a vital component to have accurate measurements. However, improper setting up the torque sensor can harm the device permanently, costing money and time. Hence, the torque sensor must be properly installed to make certain better performance and longevity.
The performance and longevity of the load cell and its reading accuracy is going to be afflicted with the design of the driveline. The shaft becomes unstable on the critical speed in the driveline to result in torsional vibration, which can damage the torque sensor. It is actually necessary to direct the strain with an exact point for accurate torque measurement. This aspect is typically the weakest point of the sensor structure. Hence, the torque sensor is purposely designed to be one of the weaker elements of the driveline.