Table of Content

25 March 2020, Volume 42 Issue 3 Previous Issue    Next Issue

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Optimization of Ammonia Coverage Ratio in Selective Catalytic Reduction System Using a Multi-objective Genetic Algorithm Wang Guoyang, Qi Jinzhu, Liu Shiyu, Shuai Shijin, Wang Zhiming 2020, 42 (3):  279-285.  doi: 10.19562/j.chinasae.qcgc.2020.03.001 Abstract ( 540 )   PDF (2360KB) ( 576 )   Save Based on the one-state selective catalytic reduction (SCR) model, a multi-objective genetic algorithm is adopted for SCR system optimization. The optimal ammonia coverage ratio target value is obtained. The tread-off relationship between NOx emission and NH3 leakage in SCR system is optimized. The effect of catalyst temperature, space velocity and SCR catalyst inlet NOx concentration on optimal target ammonia storage is analyzed. The results show that the catalyst temperature has the main influence on the target value of the optimal ammonia coverage ratio, which decreases linearly with the increase of the temperature. The simulation results of the world harmonized stationary cycle (WHSC) and world harmonized transient cycle (WHTC) show that the optimal ammonia coverage ratio map as control set-point can achieve low NOx emission while restrict NH3 leakage References | Related Articles | Metrics

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Research on Calibration of Vehicle Control Unit for Battery Electric Vehicles Based on CAN Calibration Protocol Wang Chunhua, Liu Hongfei, Bai Wenfeng, Duan Tingting 2020, 42 (3):  286-291.  doi: 10.19562/j.chinasae.qcgc.2020.03.002 Abstract ( 521 )   PDF (2610KB) ( 557 )   Save For the data measurement and calibration of the vehicle control unit (VCU) of battery electric vehicles, a calibration system based on CAN calibration protocol (CCP) is designed. The control strategy of VCU is analyzed, and the implementation process of softwares including CCP driver is expounded. By using the host computer software CANape and transmitting the command through CAN bus, the control parameters of VCU are erased and written, and the control strategy is monitored, analyzed and optimized, achieving the goal of vehicle performance adjustment. The real vehicle calibration is conducted on driving torque and the results show that the application of calibration system enhances the development efficiency of VCU and improves the performances of vehicle References | Related Articles | Metrics

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Adaptive Energy Management Strategy for Plug-in Hybrid Electric Bus Based on Equivalent Factor Optimization Yang Ye, Zhang Youtong, Zhang Biao, Hu Shaoyi 2020, 42 (3):  292-298.  doi: 10.19562/j.chinasae.qcgc.2020.03.003 Abstract ( 503 )   PDF (2820KB) ( 539 )   Save A real-time energy management strategy based on equivalent factor optimization is proposed for a plug-in hybrid electric bus (PHEB). Firstly, a fast calculation method of equivalent factor (EF) is designed, in which the range of EF is determined first according to the power parameters of vehicle, then the EF is quickly calculated by shooting algorithm. Next, an adaptive equivalent fuel consumption minimization strategy (A-ECMS) based on linear decline of battery state of charge (SOC) is proposed, and by utilizing the vehicle position information provided by the vehicle global positioning system (GPS) to update the equivalent factor online, the real-time tracking of reference SOC is achieved. Finally, a comparative simulation on A-ECMS is conducted against rule-based strategy, standard ECMS and dynamic programming strategy, and the results show that the A-ECMS proposed based on equivalent factor optimization has best control effects in both fuel economy and robustness of SOC control References | Related Articles | Metrics

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Study on Multi-vehicle Coordinated Lane Change Strategy Under Network Conditions Liu Zhiqiang, Han Jingwen, Ni Jie 2020, 42 (3):  299-306.  doi: 10.19562/j.chinasae.qcgc.2020.03.004 Abstract ( 920 )   PDF (2881KB) ( 1285 )   Save To enhance the safety, stability and efficiency in lane change, a multi-vehicle coordinated lane change strategy under the condition of intelligent network connection is proposed in this paper. The feasibility of coordinated lane change is judged by establishing a gain function based on incentive model. Based on model predictive control, a multi-objective optimization control function for coordinated lane change is built to realize distributed control in lane change process. For overcoming the difficulty in solving optimal control function, caused by the high-dimension of collision avoidance constraint and the nonlinearity of vehicle kinematics, a two-stage coordinated lane change framework is proposed, which divides the lane change process into sparse longitudinal distance phase and lane change phase. The rolling horizon optimization algorithm is adopted to solve the optimization control problem step by step. Finally, a Matlab/Simulink co-simulation is conducted based on US NGSIM open source traffic flow data, verifying the feasibility and correctness of the strategy proposed References | Related Articles | Metrics

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Design and Motion Characteristics of Cam-driven Hydraulic Variable Valve Mechanism Xie Fangxi, Zhong Bing, Yang Guozhi, Zhao Ping, Hong Wei, Su Yan 2020, 42 (3):  307-314.  doi: 10.19562/j.chinasae.qcgc.2020.03.005 Abstract ( 323 )   PDF (4959KB) ( 373 )   Save Reducing the pumping loss of gasoline engine at part load needs flexible variable valve mechanism. Cam-driven hydraulic variable valve has good engineering application prospects, but it also faces the problems of pressure fluctuation and difficult control of valve seating velocity (VSV). In this paper, the valve lift of 0~4 800 r·min-1 is continuously changed in the range of 0~8.2 mm by adjusting the throttle valve opening (TVO). The influence of piston diameter on pressure fluctuation and throttle aperture on valve seating velocity is simulated, with the piston diameter and throttle aperture confirmed, and the effect of hydraulic oil temperature on valve motion characteristics and VSV are studied experimentally. The results show that an appropriate increase of piston diameter can reduce the system working pressure and the compression wave peak , which helps reduce pressure fluctuation, and finally the chosen diameter of tappet and valve piston is 17 and 14.5 mm respectively. The throttle aperture of less than 1.6 mm can make valve seating velocity of 4 000 r·min-1 less than 0.5 m·s-1. The maximum valve lift decreases gradually with the increase of throttle valve opening under the same speed; with the same TVO, the higher the motored speed, the larger the valve maximum lift and the greater the TVO, the larger the difference of maximum lift at different speeds. Hydraulic oil temperature has little effect on the lift with the throttle valve closed; under the same TVO, the valve chamber pressure and maximum valve lift decrease gradually with the increase of hydraulic oil temperature. The valve seating velocity is insensitive to hydraulic oil temperature, with a variance of only 4.9% at different temperatures References | Related Articles | Metrics

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Sensitivity Analysis and Central Composite Design Wang Qidong, Zhang Jie, Zhang Min 2020, 42 (3):  315-322.  doi: 10.19562/j.chinasae.qcgc.2020.03.006 Abstract ( 309 )   PDF (5060KB) ( 465 )   Save Aiming at the overheat problem of a car driving shaft shroud, an optimization on the temperature field in engine compartment is conducted based on sensitivity analysis and central composite design method. Firstly, the CFD simulation of engine compartment is performed to find out the causes. Then, the main influencing factors are found by sensitivity analysis. Next, model for predicting the surface temperature of driving shaft shroud is established using central composite design method and quadratic regression equation, and the optimal combination of main influencing factors are found. Finally simulation and real vehicle test are carried out for verification. The results indicate that the surface temperature of driving shaft shroud reduces to below the limit value, effectively solving its overheat problem References | Related Articles | Metrics

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Optimization of Cooling Gallery Based on Heat Transfer and Strength of Piston Lei Jilin, Yang Yongzhong, Deng Xiwen, Dai Guoxiong, Yang Zhendong, Wu Tao 2020, 42 (3):  323-329.  doi: 10.19562/j.chinasae.qcgc.2020.03.007 Abstract ( 285 )   PDF (1364KB) ( 357 )   Save Internal cooling gallery can strengthen the heat transfer of piston greatly, but also affect the strength of piston head. In order to systemically study the effects of the structural and positional parameters on the heat transfer and structural strength of piston, and optimize the type of cooling gallery and its position in piston, the piston of a high pressure common rail diesel engine is taken as the object of study, a liquid-solid coupled heat-transfer finite element model of piston is built based on its temperature field measurement, and the heat transfer and structural strength of piston are analyzed. On this basis, the orthogonal design of experiment is adopted to analyze the effects of three factors, i.e. the type, the distance from its geometric center to the top plane of piston and the surficial area of cooling gallery, on the heat transfer and structural strength of piston. The results show that the effects of three factors have no significant difference, but in which the surficial area has the most influence, the distance from its geometric center to the top plane of piston has slightly less influence and its type has the least effect. Appropriately reducing the surficial area of cooling gallery can improve the thermal load of piston head and the stress concentration in cooling gallery, oil return hole and pin boss, and reduce deformations References | Related Articles | Metrics

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Study on Dynamic Performance of a Bus Equipped with Electronically Controlled Air Spring and Hydraulically Interconnected Suspension Qi Hengmin, Zhang Nong, Wang Dong, Zhang Bangji, Zheng Minyi 2020, 42 (3):  330-338.  doi: 10.19562/j.chinasae.qcgc.2020.03.008 Abstract ( 296 )   PDF (2397KB) ( 597 )   Save In view of the difficulty in keeping balance between the handling stability and ride comfort of bus characterized by high mass center and heavy load, a novel suspension configuration is proposed, combining roll-resistant hydraulically interconnected suspension (RHIS) and electronically controlled air spring (ECAS). Firstly, a nonlinear model for ECAS is developed based on thermodynamic theory and verified by test. Then, 9-DoF vehicle dynamic model is derived based on centroid theorem and momentum moment theorem, and into which the model for RHIS is coupled. Next, a fuzzy controller for air spring is designed for body height adjustment. Finally, simulations on the test conditions of handling stability and ride comfort are conducted to compare the performances of novel suspension and traditional one. The results show that the novel suspension system proposed can achieve the three-levels of body height adjustment and apparently improve the handling stability of vehicle while maintaining the original level of ride comfort References | Related Articles | Metrics

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Theoretical and Experimental Research on H∞ Control Suspension System with Time Delay Ji Renjie, Fang Mingxia, Li Peilin, Yan Gai 2020, 42 (3):  339-344.  doi: 10.19562/j.chinasae.qcgc.2020.03.009 Abstract ( 291 )   PDF (2265KB) ( 370 )   Save In this paper, taking the vehicle active suspension system considering time delay as the research object, by the method of combining theory and experiment, the influence of time delay on the vibration characteristics of the suspension system is studied. Firstly, the dynamic model of the active suspension system with time delay is established. Based on H∞ control theory, through Lyapunov -Krasovskii function and free weight matrix method, the matrix inequality of asymptotically stable closed-loop system with time-delay is derived, and the H∞ control law with known maximum stable time-delay is designed. Then, the numerical simulation and experimental method are used to verify the control law. The results show that H∞ control law can effectively suppress the sprung mass acceleration. Finally, the relationship between the time delay and the root mean square value of the sprung mass acceleration is analyzed under different gain and it is found that the closer the time delay is to τmax for gain control, the better the control effect References | Related Articles | Metrics

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Study on Fuzzy Control of Cooling System with Matrix Fans Wang Hongchao, Shan Xizhuang, Yang Zhigang 2020, 42 (3):  345-352.  doi: 10.19562/j.chinasae.qcgc.2020.03.010 Abstract ( 302 )   PDF (4005KB) ( 645 )   Save To enhance the efficiency of vehicle cooling system, firstly the matrix fan configuration is introduced into the traditional car cooling system, and based on which a fuzzy controller is designed. Then a co-simulation is conducted to study the effects of matrix fans with fuzzy controller on the performance of vehicle cooling system. The results indicate that under transient condition, the adoption of matrix fans with fuzzy controller can reduce the fluctuation amplitude of outlet temperature by around 76% and lower the energy consumption of fan system by 31.2%. Under the multi-mode operation of matrix fan, fuzzy controller can not only adjust the rotation speed of matrix fan according to feedback information, but also change the number of working fans with minimum energy consumption as objective, hence achieving better capability in tracking target temperature and lower energy consumption. Compared with single mode operation, the multi-mode operation has a 30.5% smaller dynamic error of temperature and an 18.8% less power consumption of fan on average References | Related Articles | Metrics

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Research on Establishing Method of User Target Loads for Light Bus Ma Jianjun, Yu Jiawei, Chen Cheng, Jing Jing 2020, 42 (3):  353-358.  doi: 10.19562/j.chinasae.qcgc.2020.03.011 Abstract ( 300 )   PDF (2123KB) ( 379 )   Save With a light bus as the target vehicle in this paper, the typical load data in different regions in China are collected and analyzed. Through the statistical analysis of load data, the target loads in each region are established by the combination of rainfall extrapolation and mileage extrapolation. Then the weights for target loads in all regions are given by using analytical hierarchy process, grey correlation analysis and structure entropy weight method respectively, with their results of weights used to establish corresponding user target loads. The target loads established with three methods are comparatively analyzed and the results show that the target loads established by structure entropy weight method are most reasonable References | Related Articles | Metrics

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Study on a Two-way High Speed Equalizer for Traction Battery Pack Based on Sepic-Zeta Hybrid Chopper Circuit Liu Hongrui, Li Bo, Guo Yixuan, Du Chunfeng, Chen Shilong, Qian Jing 2020, 42 (3):  359-366.  doi: 10.19562/j.chinasae.qcgc.2020.03.012 Abstract ( 438 )   PDF (2895KB) ( 325 )   Save A two-way high speed equalizer for traction battery pack based on Sepic-Zeta hybrid chopper circuit is proposed, which adopts different equalization topology circuits and equalization control strategies for three different operation states of battery pack. In the charging state of battery pack, Sepic chopper circuit is used as the equalization circuit, and the single cell having the highest energy in the battery pack is selected as the input of Sepic chopper circuit to conduct equalization discharging with continuous current. In the discharging state of battery pack, Zeta chopper circuit is used as the equalization circuit, and the single cell having the lowest energy in battery pack is selected as the output of Zeta chopper circuit to conduct equalization charging with continuous current. In the stationary state of battery pack, Sepic or Zeta chopper circuit is used as the equalization circuit, and the single cell having largest energy discrepancy is selected to conduct equalization discharging or equalization charging. The topology circuit of equalizer proposed is simple and easy to implement, the equalization energy is easy to control, and the equalization current is continuous and controllable, hence a speedy and efficient equalization can be achieved. Finally, an experimental platform for lithium-ion battery is built to perform equalization experiment under the three working conditions of battery pack, verifying the feasibility of the scheme put forward References | Related Articles | Metrics

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Study on Battery SOC Prediction Method for Electric Bus Based on Sparsely Sampled Data Bao Wei, Ge Jianjun 2020, 42 (3):  367-374.  doi: 10.19562/j.chinasae.qcgc.2020.03.013 Abstract ( 439 )   PDF (1406KB) ( 376 )   Save In order to enhance the accuracy of SOC prediction for electric bus battery, the SOC prediction method of electric bus battery is studied based on the battery operation data which is sparsely sampled with a sampling period of 30 s and stored on the battery database of a battery monitoring platform. Firstly, the source of sparsely sampled data is introduced, and the operation process of the traction battery of electric bus and the factors affecting the change of SOC are analyzed. The present total voltage, current and the average temperature of battery module and the battery SOC value at previous moment are selected as prediction variables, and the present battery SOC is selected as output variable, so both training and testing data set are constructed. Then support vector machine (SVM) algorithm is adopted for training while Bayesian optimization algorithm is used to find the optimal hyper-parameter combination of SVM, and a single step prediction method for the battery SOC of electric bus based on sparsely sampled data is proposed. Next, by redividing the training data set, an autonomous prediction method for the battery SOC of electric bus based on sparsely sampled data is further put forward for getting rid of the dependence on real SOC value by BMS estimation in the course of long-term SOC prediction. The results of test show that the maximum absolute error with single step SOC prediction is only 1.82%, and that with autonomous SOC prediction is also only 5.89%, both of which have high prediction accuracy. Finally, a test on different routes at different ambient temperatures is conducted with a result indicating that the SOC prediction model adopted has relatively high robustness. References | Related Articles | Metrics

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Multi-heat Source Stage-wise Coordinated Heating System for New Energy Vehicle Ding Peng, Wang Zhong, Ge Ruhai, Zhang Meijuan, Li Kaiyun 2020, 42 (3):  375-382.  doi: 10.19562/j.chinasae.qcgc.2020.03.014 Abstract ( 507 )   PDF (2355KB) ( 968 )   Save In order to reduce the energy consumption for the heating of battery electric vehicle, a multi-heat source stage-wise coordinated heating control method is designed. The heat quantity of vehicle heating system is numerically analyzed, then a multi-heat source heating scheme is proposed based on battery cooling waste heat, motor cooling waste heat and the heating of heat pump air conditioning. The distribution areas of various heat sources are optimized, the relationships between the heat quantities generated by different heat sources is established, and the control method for stage-wise coordinated heating is proposed. The method can rationally select the working modes of heating by comprehensively considering the differences in ambient temperature, the heat release sequence of heating components and the comfort requirements of occupants. The temperature distribution law in each area of vehicle is explored when the heating mode with distributed multi-heat sources is adopted. The low-temperature test on heating air conditioner is conducted with its difference to the conventional heater for new energy resource vehicle revealed. Test results show that the heating system can save 60% energy in 2 h at an ambient temperature of -22 ℃, while no power battery energy is needed at -5 ℃, verifying the superiority of the method proposed References | Related Articles | Metrics

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Lightweight Design of Body Rear Longitudinal Beam of VAHP Die-casting Aluminum Alloy Lin Jiawu, Li Xuanshuang, Chen Zongming, Chen Dong, Li Yongxiang, Geng Furong 2020, 42 (3):  383-389.  doi: 10.19562/j.chinasae.qcgc.2020.03.015 Abstract ( 617 )   PDF (4060KB) ( 690 )   Save To enhance the crashworthiness and lightweighting effects of car body in rear-end collision, vacuum-assisted high pressure (VAHP) die-casting aluminum alloy is adopted for rear longitudinal beam (RLB) to substitute its traditional steel counterpart. With the crashworthiness in rear-end collision as the focus of attention, by means of topology optimization, with consideration of the requirements of die casting forming and connection technology, die-casting aluminum alloy RLB is designed and the modularization and lightweighting of RLB structure are achieved. The results show that the filling of aluminum liquid is smooth without apparent defects such as cold insulation and shrinkage cavity, and the performances of RLB meet the requirements of rear-end collision and the stiffness in each installation point References | Related Articles | Metrics

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Lightweight Design of Carbon Fiber Composite Anti-collision Beam Chen Jing, Tang Aotian, Tian Kai, Liu Zhen 2020, 42 (3):  390-395.  doi: 10.19562/j.chinasae.qcgc.2020.03.016 Abstract ( 447 )   PDF (2395KB) ( 846 )   Save The carbon fiber composite anti-collision beam of a car is designed and its model for finite element analysis is set up, with its correctness verified by comparing the results of simulation on traditional steel anti-collision beam with test results. Then the optimal combination of its cross section shape and ply laying sequence is determined by full-factor experiment of design. Finally, multi-objective optimization is conducted on the thickness of anti-collision beam structure with NSGA-II genetic algorithm. The results show that after optimization, its crashworthiness is enhanced, its mass is reduced by nearly 65%, and its deformation mode is more reasonable in the course of high-speed crash when connected with energy-absorbing box and front side rail References | Related Articles | Metrics

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Analysis and Improvement of the Quality of Vehicle Interior Sound Induced by the Half Order Vibration of Engine Jin Yan, Zhao Tao 2020, 42 (3):  396-400.  doi: 10.19562/j.chinasae.qcgc.2020.03.017 Abstract ( 742 )   PDF (2725KB) ( 806 )   Save The roughness of vehicle interior noise during acceleration is analyzed and improved in this paper. Firstly through the analysis on the frequency characteristics of vehicle interior acceleration noise, the main cause of the roughness of vehicle interior noise is determined to be the half order noises. Then the possible noise transfer paths are investigated and the results show that the vehicle interior half order noises stem from the vibration of powertrain and transmit into the vehicle through the side bracket of transmission mounts. Finally improving schemes of reducing the stiffness of engine mounts and increasing the dynamic stiffness of the side bracket of transmission mounts are adopted. As a result, the roughness of vehicle interior noise is reduced and the quality of vehicle acceleration noise is enhanced References | Related Articles | Metrics

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Study on Boundary Extraction and Defect Identification of Molten Pool in Laser Scanning Welding of Body-in-white Song Hongwei, Wang Long, Zhang Qiuhua, Zhao Qing 2020, 42 (3):  401-405.  doi: 10.19562/j.chinasae.qcgc.2020.03.018 Abstract ( 276 )   PDF (1968KB) ( 353 )   Save The extraction process of molten pool signal and the method of removing interference signal to improve detection stability are studied in online quality detection of laser scanning welding technology. A clear image of molten pool is obtained by constructing a coaxial vision detection system with Nd: YAG laser as the heat source. For the interference of many factors on quality monitoring in production process, a method of filtering clutter and extracting key quality information is proposed by using related digital image technology. The threshold value is set reasonably by the method of maximum inter-class variance, and the gray scale image is converted into a binary image. The enhancement operator and maximum interconnection region method are used to remove the same gray level noise points caused by welding spatter effectively and obtain the accurate molten pool boundary. The influence of welding fixture and splash shape on boundary identification is analyzed, and reasonable working condition standard is set to improve the stability of quality control and reduce false alarm rate References | Related Articles | Metrics

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Fatigue Analysis of Automobile Steering Knuckle Considering the Effect of Low Load Strengthening Dong Guojiang, Du Fei, Wang Wei, Lang Yuling 2020, 42 (3):  406-415.  doi: 10.19562/j.chinasae.qcgc.2020.03.019 Abstract ( 312 )   PDF (3893KB) ( 554 )   Save Based on real vehicle test on the proving ground, combining with the finite element dynamic simulation and fatigue durability simulation of components, the difference of fatigue life prediction of automobile components with the consideration of small load strengthening effect and Miner criterion is explored in the paper. Fatigue damage risk point of the front knuckle (the road test strain monitoring point) is determined by joint analysis of indoor vehicle vibration test and finite element simulation; the strain time history of strain monitoring points of strengthened road on the proving ground is acquired, after pretreatment, time domain acceleration, extrapolation of rain flow matrix and load spectrum classification, ten-grade equivalent stress spectrum is obtained. Combining with the low load strengthening theory and the linear cumulative damage theory, the fatigue effect and damage effect of the ten-grade equivalent stress spectrum are analyzed, in contrast to the traditional Miner criteria, considering the strengthening effect of small load on the increase of the fatigue limit of the component in the process of loading, the component S-N (simplified) curve needs to be modified, offset upward from the initial S-N curve. The predicted fatigue life of the knuckle based on the modified S-N curve and linear fatigue damage accumulation theory is 40.6% higher than that of the Miner criterion. Taking into account of the effect of material strengthening behavior, this method makes up for the defect of the Miner theory which does not take into account of the interaction between different loads and the effect of material hardening transient behavior to a certain extent, and provides a new reference for fatigue life estimation and lightweight design of real components References | Related Articles | Metrics