Research On Control Strategy Of High Pressure Common Rail Diesel Engine Under Transient Condition

As the number of cars in the city continues to increase,vehicle diesel engines operate more frequently under transient conditions.Compared with the conventional working conditions,the transient conditions are difficult to control.Due to the gradual tightening of automobile emission regulations,transient conditions have received extensive attention from the industry on the basis of increasingly perfect diesel engine control strategy.For this reason,it is of great significance to carry out diesel engine transient control research.In this paper,the torque-based transition condition control strategy was used to develop and simulate the control software of high pressure common rail diesel engine.The main research contents and results are as follows:In this paper,the operating characteristics of high pressure common rail diesel engine under transient conditions were analyzed,and the torque-based diesel engine transient working condition control strategy was adopted.Considering the hardware resources of MPC5634 M microcontroller,the architecture design of diesel engine control software was divided into three parts: bottom software,basic layer software and application layer software.Based on the concept of model design,rapid acceleration/deceleration control model of diesel engine was built in Matlab/Simulink.According to functional requirements of the high pressure common rail diesel engine under transient conditions,the diesel engine control model consisted of four functional modules such as data management,working condition determination,engine management and fuel injection.They were individually used to realize sensor signal management,diesel engine condition conversion,fuel injection parameter calculation,diesel engine synchronization determination and fuel injection.In order to realize the control of the rapid acceleration/deceleration condition of diesel engine,the incremental pedal step control algorithm was designed under the rapid acceleration condition,the fuel cut-off and fuel resupply algorithm was designed under the rapid deceleration condition.The fuel injection module was taken from the physical model of the high pressure common rail diesel engine established under the GT-Power environment.According to thestructural parameters of the diesel engine used in the test,the inlet and exhaust system model,the turbocharged system model and injector were constructed.In order to verify the accuracy and reliability of the control algorithm,the Simulink control model and the GT-Power physical model were coupled for joint simulation.On the basis of completing the unit test of Simulink control model,the software interface was configured to connect the Simulink control model together with the diesel engine GT-Power physical model.The rapid acceleration/deceleration condition conversion and fuel injection control of the high pressure common rail diesel engine were studied.The simulation results showed that the incremental pedal step can improve the excess air coefficient of the diesel engine under the rapid acceleration condition and improve the indicated thermal efficiency as well.The control method of fuel cut-off and fuel resupply can realize the smooth transition of the high pressure common rail diesel engine under the rapid deceleration condition,reduce the fuel consumption and exhaust emissions of the diesel engine under this working condition.The joint simulation test results provided a theoretical basis for meeting the dynamic and emission requirements of high pressure common rail diesel engines under rapid acceleration and deceleration condition.