arrow_back_ios

Main Menu

See All Acoustic End-of-Line Test Systems See All DAQ and instruments See All Electroacoustics See All Software See All Transducers See All Vibration Testing Equipment See All Academy See All Resource Center See All Applications See All Industries See All Insights See All Services See All Support See All Our Business See All Our History See All Our Sustainability Commitment See All Global Presence
arrow_back_ios

Main Menu

See All Actuators See All Combustion Engines See All Durability See All eDrive See All Production Testing Sensors See All Transmission & Gearboxes See All Turbo Charger See All DAQ Systems See All High Precision and Calibration Systems See All Industrial electronics See All Power Analyser See All S&V Hand-held devices See All S&V Signal conditioner See All Test Solutions See All DAQ Software See All Drivers & API See All nCode - Durability and Fatigue Analysis See All ReliaSoft - Reliability Analysis and Management See All Test Data Management See All Utility See All Vibration Control See All Acoustic See All Current / voltage See All Displacement See All Load Cells See All Pressure See All Strain Gauges See All Torque See All Vibration See All LDS Shaker Systems See All Power Amplifiers See All Vibration Controllers See All Accessories for Vibration Testing Equipment See All Training Courses See All Whitepapers See All Acoustics See All Asset & Process Monitoring See All Custom Sensors See All Data Acquisition & Analysis See All Durability & Fatigue See All Electric Power Testing See All NVH See All Reliability See All Smart Sensors See All Vibration See All Weighing See All Automotive & Ground Transportation See All Calibration See All Installation, Maintenance & Repair See All Support Brüel & Kjær See All Release Notes See All Compliance See All Our People
arrow_back_ios

Main Menu

See All CANHEAD See All GenHS See All LAN-XI See All MGCplus See All Optical Interrogators See All QuantumX See All SomatXR See All Accessories See All Accessories See All BK Connect / Pulse See All API See All Microphone Sets See All Microphone Cartridges See All Acoustic Calibrators See All Special Microphones See All Microphone Pre-amplifiers See All Sound Sources See All Accessories for acoustic transducers See All Experimental testing See All Transducer Manufacturing (OEM) See All Accessories See All Non-rotating (calibration) See All Rotating See All CCLD (IEPE) accelerometers See All Charge Accelerometers See All Impulse hammers / impedance heads See All Cables See All Accessories See All Electroacoustics See All Noise Source Identification See All Environmental Noise See All Sound Power and Sound Pressure See All Noise Certification See All Industrial Process Control See All Structural Health Monitoring See All Electrical Devices Testing See All Electrical Systems Testing See All Grid Testing See All High-Voltage Testing See All Vibration Testing with Electrodynamic Shakers See All Structural Dynamics See All Machine Analysis and Diagnostics See All Calibration Services for Transducers See All Calibration Services for Handheld Instruments See All Calibration Services for Instruments & DAQ See All On-Site Calibration See All Resources See All Software License Management

Methods of torque measurement in drive train technology

Torque is an important mechanical quantity in many applications. Measuring torque precisely, in particular on rotating parts, places high demands on test bench manufacturers and users. There are two different approaches to determining torque: the direct and the indirect method.

Direct method

The torque signal is determined through direct torque measurement in the drive train. Normally, torque flanges are used for contactless measurement, for example, the T12 digital torque transducer or T40B from HBM. The direct method of torque measurement offers many technological advantages. The flange technology developed by HBM is characterized by an extremely short design and enables easy integration of high-quality torque transducers into test benches. Further advantages include higher measurement accuracy and the possibility to measure higher rotational speed.

Indirect method

Torque is indirectly determined through measurement of the electric motor's power at the converter in the drive train. Torque can be calculated together with a rotational speed measurement. Modern test and measurement equipment makes it easy to determine electric power and rotational speed in electric machines. However, relatively large errors and thus measurement uncertainties may be caused when calculating torque, since the power loss and the machine's operating states are also used in the calculation. Calibration is also very difficult. The reaction forcemeasurement method is used for indirect determination of torque. The force applied to the end of the lever arm is measured using a force transducer. Torque is determined indirectly through measurement of certain auxiliaryquantities in the drive train. This includes all methods involving measurement either of the strain resulting from shaft torsion on its surface or of the shaft's torsion angle. In both cases, torque is then calculated using the determined auxiliary quantity.

Drawbacks of the indirect method

 

Torque measurement using a force transducer

 

Determining torque through reaction torque measurement using a force transducer - e.g. a self-aligning brake (see Fig. 1) - requires complicated mechanics. Interference effects such as variations in the self-aligning brake over time or expansion of the lever arm resulting from temperature variations need to be taken into account; otherwise they may cause measurement errors. Furthermore, this method is not suitable for dynamic tests because of the large masses involved, since they virtually act as a "mechanical low pass" (see Fig. 2).

 

Determination via auxiliary quantities

 

When determining the measurand torque using auxiliary quantities, for example, strain and torsion angle, it is essential to allow for individual errors resulting from diameter and input shaft length tolerances or from a measurement error in the torsion angle. In addition, errors resulting from lacking or limited temperature compensation need to be taken into account when applying these measurement methods.