Research On Fuel Saving And Emission Reduction Control Technology Of B50 Car Idling Start-stop Condition

With annual growth of China’s vehicle sales, currently, China has become the largest vehicle sales country. This brought a sharp increase in fuel consumption, and air pollution is also getting worse. To solve these problems, domestic and foreign government have introduced more strict vehicle fuel consumption and emissions regulations. Car companies also do the technology research on the fuel saving and emission reduction. B50 vehicle with stable quality and excellent driving performance enjoy a good reputation among users, but some users complained B50 fuel consumption and emissions high. Based on the above background, this paper proposes to B50 vehicle saving emission reduction research. B50 vehicle is in production models, thus the saving emission reduction technology development shoule confirm that the vehicle small change, increasing costs less and short development cycle, increasing the B50’s cost-effective and market competitiveness.Idling start-stop technology fuel saving is remarkable, the vehicle changes less, the cost increase less, so this papeer select this technology as the research direction of B50 fuel saving and emession reducton. BSG(Belt driven Starter Generator belt drive start generating machine) start-stop system is a micro-hybrid technology. It can achieve the idle start-stop function, brake energy recovery function and low-speed torque assist functions, and the starting noise is also low, so this paper select BSG start-stop technology as the solution of B50 fuel saving and emession reducton. The engine FEAD(front end accessory drive) design and the cooperative control of the BSG motor, engine and automatic transmission are the key technology of fuel saving and emession reducton. This paper uses mathematical modeling, simulation and optimization, control strategy simulation and analysis, and experimental verification. The main research contents are as follows:1.This article builds the BSG start-stop system engine FEAD(front end accessory drive) dynamics model by using the Admas software. The structure and performance parameters of the tensioner is Optimally designed, the optimal design parameters of the tensioner’s performance and structure is determined. Applying the parameters to simulate and analysis the FEAD system, the simulation results demonstrate the FEAD system design can start the engine fastly and stably.2.Depending on the BSG integrated starter generator’s function and performance requirements, motor type is selected, and the BSG Motor mathematical model is build. For improving the BSG vehicle’s starting performance and low-speed acceleration performance, this paper developed a BSG motor excitation current control strategy. BSG motor drive system simulation model is biuld in Matlab / Simulink to analyze the excitation current control strategy’s influence on BSG Motor’s steady-state performance and dynamic performance. Simulation results show that: the proposed excitation current control strategy makes BSG motor with low-speed high torque and fast response characteristics, and improve the engine’s starting performance and start-stop function stability.3. Based on driver safety, driving habits, driving comfort and fuel economy considerations, the start-stop system vehicle control strategis are developed, and set the important parameters’ thresholds. BSG vehicle simulation model is established in the CRUISE software. The simulation results show that the idle start-stop system can effectively reduce fuel consumption. For the idle start-stop vehicle in the initial stage emissions worse problem, this paper presents the engine and transmission cooperative control strategies. By controlling the transmission to upshift to increase engine fuel injection quantity, shorten the catalyst light-off time, thereby reducing vehicle cold start emission pollutants.4. BSG start-stop system’s key components are developed, and BSG start-stop system prototype is structured. On the rotating hub and urban real road test stand, the real vehicle fuel consumption is tested. The results prove that the BSG start-stop system control strategy can effectively reduce the vehicle fuel consumption. In the laboratory the vehicle emissions are tested with the emission control strategy on and off. The results show that the control strategy can accelerate catalyst ignition, which can effectively reduce vehicle infancy emissions. BSG prototype does the cold start test in-25 ℃. The test result is that the vehicle can successfully start in firt time, and the starting time is less than half second, and the engine start stably. Test proves that the FEAD design meet the requirements, BSG motor starting torque control strategy is correct and effective. After the vehicle performance tests are passed, test the vehicle start-stop system boundary conditionm, the vehicle safety and functions. All the test results meet the function and performence requirements, and the prototype passes the acceptance.Through the development of BSG B50 car start-stop system and vehicle bench androad test, this paper studied the B50 fuel saving and emission reduction technologies in idling start-stop conditon. The results show that the cooperative control technology of BSG motor, engine and automatic transmission is correct and effective. B50 vehicle save the fuel more than 5% in NEDC cycle, and the emissions pollutants reduced by 10% to 20%. The BSG start-stop system prototype functionality and performance test meet the driver’s safety and comfort requirements. This paper’s reaearch result provied the technical solutions for fuel saving and emission reduction, it has practical significance for promoting BSG system applicaton, it laid the foundation for the practice 48 V system in the car.