Study On Combustion Noise Of Diesel Engine Control With More Times Pilot Injections

The noise problem generated by automobile engines has always affected people's lives.With the establishment of various regulations,the improvement of engine noise is facing a great test,and the noise problem of diesel engines is more prominent.Through the use of direct injection diesel engine electrical control system to accurately control multiple pre-injection parameters and throttle opening,this project can effectively control the combustion noise of diesel engines and improve their sound quality to some extent.Firstly,the combustion noise experiment of each working condition of the diesel engine is carried out.The original state of the experimental model is a pre-injection strategy.The experimental data shows that the combustion noise at different speeds and loads is very different.The combustion noise of the experimental model is It is more serious under idle conditions,and the combustion noise under other load conditions is within the acceptable range.Secondly,in order to reduce the combustion noise under idle speed,the effects of multiple pre-injection techniques on combustion noise are studied,and the effects of multiple pre-injection strategies on cylinder pressure,pressure rise rate,heat release rate,combustion noise and one-meter average noise are analyzed.The experimental results show that after using this technology,the peak value of pressure rise rate and heat release rate is significantly reduced,the combustion noise is obviously improved,the cylinder pressure spectrum is reduced in the medium-high frequency range of 500~5000 Hz,and the radiation noise of the whole machine is also Obvious reduction.Based on this experiment,the influence of intake air quantity on diesel engine combustion noise and speed fluctuation is studied.On the basis of two pre-spraying,the combustion process of diesel engine is controlled by changing the opening degree of the throttle valve,so as to achieve the purpose of improving combustion noise.The results show that with the decrease of the throttle opening,the cylinder pressure and pressure rise rate curves are obviously reduced,and the combustion noise is also reduced.However,the throttle opening needs to be controlled within a certain range,otherwise it will cause the speedfluctuation.Then,the engine simulation software GT-power is used to simulate the combustion noise of the diesel engine.On the basis of two pre-injections,the curves of cylinder pressure and pressure rise rate of different throttle opening degrees are simulated and compared with experimental data,so that the simulation results are consistent with the experimental results.Next,the simulation calculates the change of combustion noise of the first pre-injection and the second pre-injection in the two pre-injection strategies at different pre-injection angles and pre-injection quantities,respectively.Finally,based on the experimental data,the sound quality analysis of the model is mainly compared with the differences in loudness,roughness and sharpness of the two pre-spray strategies.The results show that the sound quality of the two pre-spray strategies is better,in which the loudness and roughness values are greatly reduced.