Study On Calibration And Optimization Of Gasoline Engine Powertrain System

With coming of innovation of energy conservation, environmental protection and low carbon society, auto industry will face big challenges. Except large-scale development of new energy car currently, how to improve traditional car that play their full potential is a subject of extensive research in these years. One of key points is efficiency improvement of powertrain system. A lot of new technologies are introduced, such as GDI, turbo charge, VVT, half mode, DCT, CVT etc., powertrain becomes more complicate and hardly to control. Methodology of calibration and optimization will be introduced to optimize control parameters of powertrain system in order to play its full action. Methodology of calibration and optimization will be introduced to coordinate engine and transmission in order to play its full performance. Methodology of calibration and optimization will be introduced to reduce development period and cut down budget. These series issues are worthy to be studied and solved by taking appropriate measures.Some consultant companies in the world are researching in this area for several years, such as Ricardo, AVL etc., but most of them only limited in principle investigation and rarely applied into production. This topic has seldom been discussed among China's auto industry too. The institutes study is limited into the theoretical level, and manufacturers consider this reserching relatively advance and no time to attend due to pursuit of the maximum interests. Therefore the investigation in this area is not maturation in China auto industry. Calibration of engine and transmission with little coordination are still in their original status, so that we can not say compromise optimization.The study in this thesis is based on the HQE project which is completely new development by FAW for parade, integrated with the first V12 engine in China and TB68 automatic transmission which constitude powertrain system. Collaboration on optimization is in sight of powertrain by theoretical analysis and experimental study. A first calibration of V12 engine in our country has been studied. A first productive research of model-based calibration in domestic has been carried out, whole process including advanced DoE design utilized Sobol space filling has been discussed, collect engine response data according to this design, basing on measurement data to build engine response models, control parameters have been optimized in these models which was used to generate INCA calibration map. The conclusion shows that calibration time has been greatly saved compared with traditional method. Repeatable investigation must be supported by powerful tools, so a world level platform of calibration tools has been established depending on experience in this paper which is a basement of all research. The first twin ECU control mode in China as well as its architecture and calibration optimization method has been studied. A breakout of twin ECU calibration has been implemented so that FAW is unique company who masters this technology in domestic field. The optimization of shift schedule in some AT models has been investigated, some calibration methodology have been carried out which help to establish own capabilities. The relationship and constrains among powertrain as far as coordinator optimization, evaluation, system modeling have also been analyzed.Study on calibration and optimization methodology of powertrain system is very closely to production development, therefore it has great applicable value for engineer. This technology breakthrough is in leading position in our country which greatly improve the development ability of FAW. The results of this study have been fully proven by the perfect performance of HQE car during the National Day parade on the 60th anniversary.The mainly work and investegation have been done in this study as below:Optimization of model-based calibrationIn order to look for high efficient solutions about optimizated calibration, using MatLab tools to assist the investigation is one of approach. Beginning from design DoE by Sobol space-filling experimental, then collecting engine response data according to this design combined with some filter function and constraints to obtain available test data, output response models of engine have been built, such as torque, fuel consumption, exhaust temperature and other models. Finally control parameters and calibration data have been optimizated basing on these models, and optimization results of the complexity engine control parameters will be obtained in less expense and short time by this methodolygy compared with traditional method, whilst the performance of engine will be developed as good as possible.The investigation results show that using this method only spend half time to finish calibration optimization, but quality is compariable with traditional methods, so this methodolygy of calibration optimization about complexe system will be future direction.Claibration tools about powertrain systemCorrectly calibration tool chains will bring positive effect in powertrain development work.A set of calibration tools has been integrated in this study according to different requirements during actual development. So that all devices have been combined together organically, and have been taken full effect, which hence provide strongly supporting in study.Target vehicle speed following function has been programmed by softwarePre-programmed curve data of target vehicle speed, such as NEDC, has been converted into CANape*.mdf format file, which is always displayed on playback window by monitoring function of software. The driver can control the throttle to lead actual vehicle speed always following the target curve of vehicle speed, and easily to be implemented on various road conditions without long-term occupying of the rest roller. This method is very practical and ingenious because it can simulate various drive cycles and acceleration, it is rare similar applications in domestic.Shift Schedule Optimization of automatic TransmissionShift schedule optimization of automatic transmission will influence performance of vehicle directly, although there are many theoretical intruction in book, papers and other literature in domestic, but most of them stay on paper, how to optimize it in production has to be faced by many automobile manufactories. The optimization of normal mode, slop mode, cold mode, hot mode and manual mode and other mode have been investagated in this study from a practical point of view. The results show that the optimization of shift schedule of red flag parade vehicle catch the international advanced level, shift characteristics meet critical requirements, and self-development capacity has been established in this development process.Unlock strategy optimization in coast down of Automatic TransmissionThe torque converter will be unlocked when the vehicle is in coast down because the limitation of transmission hardware. In some cases, the torque converter locks up or not due to strategy when accelerating again. Normally it is better to lock up torque converter as much as possible, which increase efficiency of torque transfer, thereby reduce fuel consumption. Therefore, replace lock-up after upshift by lock-up before downshift in order to compensate this defect. It will expand the scope of lock-up torque converter and improve efficiency.Automatic downshift optimization strategy from normal mode to manual mode Automatically downshift strategy from normal mode to manual mode has not been considered in software and hardware design of this transmission, and it is patent of Toyota and Mazda by hardware method. So considering the driver willing of control and pursuit power by select manual mode, it is better to improve drivability by optimazte shift schedule to implement automatically downshift in such mode switching. On the other hand, increasing torque transfer and reduce the acceleration fuel consumption because expand the scope of lock-up in manual mode, and lock-up area of low gear is biger than high gear.Twin ECU optimizationUtilize twin ECUs to control engine is first time in China. Calibration optimization of twin ECUs is different from previous single ECU and there are a lot of special characteristics, so this caliabrtion is still blank in domestic. At first, correct calibration device is set up to adjust parameters in ECU. Second, group concept has been adopted in INCA to ensure the calibration data adjustment among two ECUs in synchronization. Control parameters in each ECU can be adjusted seperatly in some special occasions to achieve cylinder cut off, detonation and other special air-fuel ratio control for itself which assist optimization of calibration. Mean, minimum, maximum and diavation method between two banks of twin ECU calibration have been introduced due to special case to meet different requirements.Powertrain Calibration OptimizationEngine and transmission are more complex in future so that technical solution and control parameters are diversity. In past years, engine and transmission have been calibrating in separately, so it is difficult to meet the future requirement of vehicle development. The perspective of this study is from the powertrain, the relationship among optimization, constraints and requirement have been considerated in general between engine and transmission, effective and integrated solutions have been pointed out to achieve optimal control for powertrain system. In addition, the evaluation result has not been paid more attention in many previous studies, because they always think it is enough to finish functional development. However, the vitality of production is good market performance and meets the various needs of custom which is significance that convert researching into merchandise. Therefore, the evaluation process and experience were summed up during this study, all aspects of the evaluation have been introduced in systematic and completely which will be helpful for evaluation of product development results. Finally, the building of powertrain model and future direction of development has been brief analysised, this is maybe basement for further research. However, the application of powertrain model is also limited in theoretical research due to the current technologies limitations, it is long distance to apply calibration optimization process to actual product. I believe calibration optimization can be fulfilled on accurately and complex vehicle model sooner.