Research And Engineering Application Of Test Technology For Exhaust Pollutants From Vehicles

The low-level testing technology for vehicle exhaust pollutants under driving mode condition restricts badly the implement of Inspection/Maintenance system in our country. The theory, technology and application of control about ASM and VMAS running Mode are researched theoretically and experimentally. The results have theoretic significance and engineering applied value for control of not only ASM and VMAS test but also other kindred vehicles and engine test-beds.The scheme of vehicles exhaust testing system under prescribed driving mode condition is constructed. The model of vehicles running resistance on chassis dynamometer is established by means of dynamics analyzing for the vehicles running on road and on the chassis dynamometer. Based on the principle that rotating acceleration of driving wheel on the chassis dynamometer is equal on road, electrical simulation conception of vehicle inertia is put forward and the corresponding mathematical model is established. The theoretic bases of electrical simulation for vehicle running resistance and inertia are offered.The performance characters of air cooling eddy current dynamometer are analyzed by theoretic analysis and experiment research. The relationships among absorbing torque, magnetizing current and rotating speed are nonlinear, time-varying. The absorbing torque responding for magnetizing current is slow, which offers the necessary basis for researching the methods of running mode control.The detailed project of human-computer compound controls about ASM and VAMS is designed. To reduce the absorbing torque interference of eddy current dynamometer cased by variable rotating speed, the decoupling control project of compensation torque is put forward, which compensation torque is determined by the feedback and prediction of vehicle speed on testing conditions.The dynamometer torque controller of ASM is designed and developed based on P-Fuzzy-PI compound control. In order to solve the problem that vehicle instantaneous acceleration can not be test exactly, the method applying the predictive method to change the setting value of the torque loaded by the dynamometer with normative driving operation is used, so the vehicle inertia can be simulated electrically. P-Fuzzy-PI compound controller has not only good dynamic and homeostatic capability but also good robustness, which solves the control problems aroused by time-varying and nonlinear parameters of air cooling eddy current dynamometer. Besides, the appliance of predictive control improves actual responsive speed of the torque and the precision of inertia electrical simulation greatly.The dynamometer torque controller of VMAS is designed and developed based on DMC and decoupling control. The DMC with fuzzy self-correcting gain coefficient and feedback predictive compensation decoupling is used. DMC predictive control improves torque responsive of dynamometer. The fuzzy self-correcting of model gain improves the robustness of control and the adaptability of vehicle types tested and testing conditions. At the same time, the feedback predictive compensation torque decoupling for vehicle speed reduces the maximum impacting torque value of VMAS testing effectively. The engineering setting methods of the torque loaded by dynamometer on vehicle exhaust test under driving mode condition are researched. The mechanism to develop the chassis dynamometer with bigger diameter rollers is put forward. A new rolling resistance (coefficient) test system is developed based on wheel torque sensor, which offers a new method for deeply researching the rolling resistance of the wheels on the rollers.An experimental system that can simulate working mode control of ASM and VAMS test is developed. The experiment results show the rationality of the systemic project and the feasibility of the total design, which solves core technology problems of vehicle exhaust test under driving mode condition.