Recognition Of Indicated Mean Effective Pressure And Cylinder Pressure Using Flywheel Speed

Indicated mean effective pressure is the indicated work done by engine per cylindervolume which can be used for engine torque control. IMEP based on cylinder pressuresensor is costly to obtain, only limited. in a lab environment. So other indirectly low-costestimation methods of cylinder pressure and IMEP will be of of great significance forengine online monitoring, diagnosis and control.Firstly in the four cylinder engine each cylinder acting range is basically independentand the power region of fired cylinder is approximately in accordance with the regionthat flywheel speed rises from minimum to maximum. The individual cylinder IIMEP,speed, and mean speed is obtained by programming, and new model about individualIMEP and speed fluctuation is developed under the theoretical model of single cylinder forsix different operating cases. Then put forward the IMEP common model withoutdetermining the engine running cases. The absolute error of the mean indicated torquebased on IMEP common model is between 4N·m.Secondly, the existing single-zone combustion model of gasoline engine is simplifiedas a five parameters model of heat dissipation scale coefficient, specific heat ratio, wiebeefficiency coefficient, wiebe form coefficient and combustion duration. Least squaresmethod is used to fit the region of the cylinder pressure curve. Under the method of theexisting literature the empirical model formula of the five parameters was obtained. finallyIMEP, Mass fraction burned 50% and 90 was calculated based on the regressed model ofcylinder pressure.Finally the last chapter gives the model of cylinder pressure from intake valve closingto the exhaust valve opening on the basis of previous chapter and the key parameters ofthe mode is regressed. The effect of initial pressure estimation error and modeling error oncylinder maximum pressure and IMEP was calculated.