Capabilities of Hydrodynamic Dynamometers for Dynamic Internal Combustion Engine Test Benches compared with Electric Dynamometers

摘要

Instead of electric dynamometers also hydrodynamic dynamometers can be used to load an internal combustion engine at a test bench. Hydrodynamic dynamometers combine high power ratings with low moment of inertia and offer especially in case of high power ratings a good alternative to electric dynamometers. Despite these advantages hydrodynamic dynamometers are not widely used in dynamic testing as modeling and control is due to their nonlinearities a nontrivial task. Using new concepts for torque control and speed control a significantly better performance with respect to the classical implementation is achieved thus opening a new path for the intended use of hydrodynamic dynamometers in dynamic testing. Hydrodynamic dynamometers are compared with electric dynamometers in reproducing operating conditions an internal combustion engine would undergo in a vehicle. Therefore, measurements have been performed at a heavy duty truck engine test bench with both type of dynamometers and different dynamometer controls. The dynamic capabilities as well as the effects of employing a purely passive dynamometer and different dynamometer controls are analyzed.