Dynamic Analysis of Spark Ignition Engines 2012-36-0138
To attend the new tendencies of the automotive market, new technologies must be used throughout the engine conception. One way of improving the project is to use computational numerical simulation, predicting engine behavior in a wide range of situations.
This paper presents a methodology to estimate the engine characteristic parameters necessary to numerical simulation. Morse test was used to determine friction power, mean effective pressure friction and friction torque, considering the engine behavior during cylinder ignition cut-off. In this test all the results were compatible with manufacturer data, which validates the methodology.
To define the moment of inertia, it's also proposed a fuel cut methodology, associated with the Morse test, because the torque values measured by dynamometer after the fuel cut did not correspond to the real value. Thus, plausible values of engine moment of inertia, very close to values obtained by software, were obtained.
It was also determined a system model from the variation of the throttle open angle, generating a transfer function which represents the engine behavior under the test conditions.
Lastly, it was analyzed the course of cylinder inner pressure during engine acceleration and it was observed that the thermodynamic cycle increased evenly and without deformations.