Like many other types of sensors, torque sensors use strain technology for measurement. The sensor is usually a metal elastomer on which a strain gauge (SG) is mounted. The strain gauge is firmly attached to the elastomer.
If the external load acts on the sensor, the measuring body will deform and the resistance of the strain gauge will change accordingly. In this way, the load can be measured by the change of resistance.
However, when measuring torque, the sensor does not always rotate. Typical applications of non rotating devices are standard testing machines and mixer measurements. In the latter, the sensor is supported by the motor housing and the drive shaft passes through the center hole of the sensor.
In most applications, the sensor is part of the rotating drive train between the object under test and the dynamometer. For example, the tested object may be an internal combustion engine, gearbox or motor.
The torque sensor has other functions. In addition to torque, other measured variables can be recorded. This is optional. The most important parameter is the speed, which can be measured by the light transmitting slotted disc on the rotor. When the sensor rotates, the beam will be interrupted at certain intervals. When the time window is constant, the speed can be calculated only by the number of pulses.
Another important feature that many users are interested in is power, which can be calculated by multiplying torque by speed. In addition, many torque sensors have a built-in temperature sensor, for example, which can tell us the operating temperature of the sensor or power train.
The torque sensor can be used for static or dynamic measurement. An example of dynamic measurement is the continuous acceleration and deceleration (or "braking") of a rotating element or the pulsating torque generated by the power stroke of an internal combustion engine. In addition, dynamic torque can also occur without rotation at all. However, in most applications, such as engine test stands (internal combustion engines or motors), dynamic torque is related to rotation.
In the field of R&D, torque sensor is an inevitable requirement for testing various engines, motors and drive systems. When you need to improve the efficiency of the drive system, accurate torque measurement is essential because it can determine the friction loss and minimize it. In electric and hybrid power systems, it is important to travel and improve efficiency; In hybrid and internal combustion engines, the key is to reduce carbon dioxide emissions as much as possible to achieve environmental friendliness.
In addition, the torque sensor can also be used for off-line detection of transmission and engine or functional test of rotary switch. However, some applications look completely different, such as using torque sensors to monitor the liquid mixing process, or installing torque sensors in the marine power system. Some sensors are also used as reference sensors in standard testing machines. HBM can provide shaft or flange torque sensors for a variety of applications.
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