Torque measurements in automotive applications often present a special challenge. In some applications there is a preference for covering multiple measuring ranges with only one torque sensor. There are several approaches for a solution to this challenge. The measuring range of the sensor can be extended electrically or mechanically, for example. In the first case, however, accuracy suffers because factors contributing to measurement uncertainty such as hysteresis, signal noise and the temperature response of the zero point are reinforced with the spread of the measuring range. In the other case the mechanical properties deteriorate due to the highly complex structure of the measuring body. HBM has therefore followed a different approach, developing the T12HP digital torque flange with FlexRange. This sensor covers the entire measurement range with only one spring element, with an enormously high level of accuracy.
Requirements for motors and automotive components – greater energy efficiency, lower consumption and longer ranges – are steadily rising. This also means higher requirements for accuracy in development and research – and thus for testing equipment as well. Torque measurements are a crucial factor for many testing applications in the automotive industry. This is especially demanding if measuring ranges of different sizes have to be covered during a measuring process, as for example in engine tests. Then a torque sensor has to acquire both high and low torques, depending on the test – with uniform accuracy over the entire measuring range. The main challenge is to achieve a balance between measurement accuracy and error tolerance. In many applications, for example brake tests, the peak torques that occur are very high in comparison to the average measured torques. The nominal (rated) measuring range of the sensor is dimensioned appropriately to ensure the sensor is not overloaded, damaged or even destroyed by peak torques. Peak torques represent the maximum torque in the application. If a sensor is adjusted to the maximum torque, however, it may possibly be overdimensioned for measuring the other torques that occur during the test. Over-dimensioned sensors have a disadvantage: important data sheet information, which must be used to to evaluate errors, refers to the nominal (rated) measuring range, not to the average measured torque. The relevant error evaluation may therefore produce an unfavorable result because important parameters named in the data sheet such as the temperature response TC0, non-linearity and the hysteresis as well as effects due to parasitic loads generally refer to the nominal (rated) measuring range of the sensor.