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Torque measurement improves with use
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01/04/2007
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A novel method of torque measurement based on the evaluation of speed signal sensors is being tested by Magna Powertrain in Austria, writes Roger Bishop.
Systems installed on BMW X3 and X5 vehicles are currently being evaluated.
The development arose out of Magna Powertrain’s need to measure torque in transfer cases. With closed-loop control being applied to more and more on-vehicle systems – for example, torque distribution between left and right wheels – the further development of a method that uses the vehicle’s ABS rotational speed sensors was irresistible.
Called TOMCAT (TOrque Measurement Control for All Transmission types), the system can be applied to front/rear/all-wheel drive passenger cars, trucks and other vehicles. It is possible to analyse torque in the longitudinal direction (front or rear torque at the cardan shaft) as well as torque on lateral shafts at torque vectoring units.
In a paper, Magna Powertrain engineer Thomas Karer describes how the measurement is carried out. “Having started the car, the torque is specified by detected driving manoeuvres. Depending on the manoeuvre, we can specify an accuracy class that improves more and more during driving. In our test vehicles, we reach an accuracy of about ±15Nm after an average driving time of 30s.”
TOMCAT can be used for continuous powertrain torque measurement, to detect power-take-off torque in truck systems and to optimise gear-shift strategy. However, Magna says it also has the potential to solve acoustic problems in the driveline, and detect stress and wear in powertrain components.
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Author
Roger Bishop
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