Research On Thermal Property Analysis And Optimization Of High-Pressure Common-rail Electronic-Controlled Diesel Engine ECU

Diesel engine electronic control unit (ECU) is the key component of the diesel engine control system, and its thermal property is related to whether the entire diesel engine system can work safely and reliably. With the development of microelectronic technique, ECU is developing towards miniaturization and integration trend, and then the temperature turned into the main factor affecting the performance of ECU. Therefore, this paper takes a domestic electronic control diesel engine ECU as the research object, studies factors that affect the thermal performance of the temperature field and thermal stress by means of simulation and experimental, and then carries on various thermal optimized analysis to the ECU.This paper has established the three-dimensional geometric model of ECU by Pro/Engineer, then imported the model into Icepak, completed the ECU temperature field simulation model by dividing the mesh, determining the material parameters and boundary conditions. Then the ECU thermal stress simulation analysis model was established by using ANSYS Static Structural. This paper also has established the ECU thermal test system and verified the accuracy of the ECU simulation model. Test results show that the model has a high precision.Based on the established thermal analysis model, this paper has studied the effects of ECU conditions, environment temperature, plateau environment and other factors on the temperature field of ECU. It has studied the ECU temperature fields of six typical diesel engine operating conditions, and the maximum load condition is determined. It has investigated the influence of different environment temperature and altitude on the ECU temperature field. The results show that the ECU temperature rises with the ambient temperature increases linearly, and decreases 5.86-6.16℃ as the altitude increases by 1000m.This paper has studied the influence of PCB material properties, fixed position and environment temperature on the thermal stress and thermal deformation of ECU. Research shows that the maximum thermal stress and the maximum thermal deformation of PCB board are linear relationships with the growth of the thermal expansion coefficient of the substrate material, and the maximum thermal stress usually appears in the vicinity of the fixed constraint position. When the ambient temperature is room temperature, the thermal stress and the thermal deformation of ECU are in the minimum. The expansion and the cooling shrinkage process will lead to the increase of thermal stress and thermal deformation while the temperature is above or below the normal atmospheric temperature.This paper has completed the thermal property optimization of ECU and sample experiments. Due to the location of high temperature components, it has proposed three optimization layouts, and selected the optimal scheme through simulation analysis. It also has compared the diesel oil and air convection cooling effects, improved the cooling structure of the ECU case, re-designed the cooling fins layout. The optimized ECU temperature decreases 3.5-5℃, and the difficulty of processing and manufacturing costs are also reduced. According to the optimization program, this paper has completed the comparative experiment. The experimental results show that the optimized ECU thermal property has been improved.