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 fairly simple to measure. Dynamic torque, however, can be difficult 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 to condition the shaft or perhaps a member linked to the shaft with a number of permanent magnetic domains. The magnetic characteristics of these domains will be different according to the applied torque, and therefore could 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 essential, as well as a way to have the signal from the rotating shaft. This can be accomplished using slip rings, wireless telemetry, or rotary transformers. Newer types of torque transducers add conditioning electronics and 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, such as /-10VDC.
A more recent development is using SAW devices connected 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 in 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.
An additional way to measure Torque Sensor is through twist angle measurement or phase shift measurement, whereby the angle of twist resulting from applied torque is measured by utilizing two angular position sensors and measuring the phase angle between the two. This procedure can be 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 the axial reaction force experienced by the inputting shaft/pinion can be associated with the torque felt by the output shaft(s). The axial input stress must first be calibrated up against the output torque. The input stress can be easily measured wbtbtc strain gauge measurement from the input pinion bearing housing. The output torque is readily measured utilizing a static torque meter.
The torque sensor can function just like a mechanical fuse and is also 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 must be properly installed to make sure better performance and longevity.
The performance and longevity in the Multi Axis Force Sensor and its reading accuracy will be afflicted with the design in the driveline. The shaft becomes unstable on the critical speed in the driveline to result in torsional vibration, which can harm the torque sensor. It is required to direct the strain to an exact point for accurate torque measurement. This point is typically the weakest point of the sensor structure. Hence, the torque sensor is purposely made to be one from the weaker aspects of the driveline.