Estimation of Indicated and Load Torque from Engine Speed Variations
The importance of control systems and diagnostics in vehicles are
increasing and has resulted in several new methods to calculate better
control signals. The performance can be increased by calculating
these signals close to optimum, but that also require more and precise
information regarding the system.
One of the wanted control signals are the crankshaft torque and
the thesis presents two different methods to estimate this torque
using engine speed variations. These methods are Modeling of the
Crankshaft and Frequency Analysis. The methods are evaluated and
implemented on for a four cylinder SAAB engine. Measurements are
made in an engine test cell as well as a vehicle.
The results show that the Modeling of the Crankshaft method does
not produce a satisfying estimation, with a difference of about 200%
between estimated and calculated torque. On the other hand, the
Frequency Analysis provides an accurate estimation of both mean and
instantaneous indicated torque, with a maximum difference of ±20%
between estimated and calculated torque.
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Last updated: 2021-11-10