Research On The Key Control Parameteters Of Gasoline Engine Performance Under Sudden Change Conditions

The increase in the number of cars has also brought about energy crisis and environmental pollution,In the current context,The country introduced strict emissions and fuel consumption regulations,It is urgently needed for energy saving and emission reduction of automobiles.However,most of the engines used in cars are kept working under transient conditions,The actual performance under transient operating conditions sometimes differs significantly from the results obtained under steady state bench tests.Improve the thermal efficiency of the engine under transient operating conditions,which is of great significance for energy conservation and emission reduction.Therefore,based on a large number of steady-state bench tests for multiple gasoline engines and a large number of test data acquired under transient whole-vehicle test conditions,this paper summarizes them,The key control parameters of gasoline engine performance under steady-state bench conditions and rapid change conditions were studied respectively.Analysis shows that under steady state conditions of the gantry,Excess air ratio,intake air density,charge coefficient,ignition advance angle and indicated thermal efficiency have an effect on engine performance.In which the intake air density and the charge coefficient increase with the increase of the load.The ignition advance angle decreases with the increase of the load,The ignition advance angle affects the position of the 50%combustion point,which affects the power of the engine.The excess air ratio will affect the combustion process in the cylinder,which will affect the engine dynamics and economy.Indicating the thermal efficiency represents the good or bad of the in-cylinder heat transfer process.For emissions,CH emissions are lower,CO emissions are also low at low loads,but CO emissions are relatively high at high loads,NOx emits the most at medium load.Whether it is the case of rapid acceleration or slow acceleration,the working process of a gasoline engine can be understood as a series of steady-state process transitions,and the control parameters in the change process determine its performance parameters:The deviation of the control parameters from the steady state operating conditions will result in a deviation of the performance parameters and steady-state conditions under variable operating conditions.Special attention should be paid to the control of the ignition advance angle,excess air ratio,etc.of the engine under sudden change conditions,and the difference with the calibration conditions of the gantry,These are often the key factors leading to differences in transient and steady state performance.