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25 December 2018, Volume 40 Issue 12 Previous Issue    Next Issue

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Optimization of On/Off Control Strategy and ECMS Strategy for the Range-extender of Electric Urban Bus Xu Ning, Lou Diming, Tan Piqiang, Hu Zhiyuan 2018, 40 (12):  1377-1384.  doi: 10.19562/j.chinasae.qcgc.2018.012.001 Abstract ( 387 )   PDF (4455KB) ( 511 )   Save This paper aims to solve the problem of high fuel consumption and large charge/discharge depth of lithium battery in charge sustain stage for the range-extended electric bus with single point on/off energy management strategy. Firstly the single-point on/off strategy and the equivalent fuel consumption minimum strategy (ECMS) are optimized and verified by simulation. Then a verification test is carried out on a semi-physical platform. The results show that in charge sustain stage, after single-point on/off strategy is optimized, the fuel consumption per 100km reduces from original 39.1L to 36.23L and the cycle charging factor of lithium battery reduces from 19.8/100km to 13.2/100km, decreasing by 7.3% and 33.3% respectively; and with optimized ECMS, the fuel consumption per 100km reduces again to 35.22L and cycle charging factor further reduces to 9.9/100km, lowering by 9.9% and 50% respectively compared with the original single point on/off strategy References | Related Articles | Metrics

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Numerical Investigation on the Effect of Ambient Pressure on the Morphological Characteristics of a Multi-Hole GDI Spray Zhao Hongxue, Jing Daliang, Ding Haichun, Shuai Shijin, Pang Changle 2018, 40 (12):  1385-1392.  doi: 10.19562/j.chinasae.qcgc.2018.012.002 Abstract ( 213 )   PDF (3290KB) ( 332 )   Save In this paper, the effect of ambient pressure on the morphological characteristics of a multi-hole gasoline direct injection (GDI) spray is simulated in CONVERGE. Firstly, a constant volume vessel spray model is established based on the injector parameters. According to the test results of high-speed imaging and phase doppler particle analyzer (PDPA), the Sauter Mean Diameter (SMD), spray morphology and penetration distance of the model is verified. Based on this, a detailed study on the spray morphological characteristics under 0.1,0.5 and 1MPa ambient pressure conditions is conducted. The results show that, the spray is compressed and contracted to the central axis of the injector and the penetration distance decreases under elevated ambient pressure. Due to the impact of the spray on the airflow in the vessel, a strong air entrainment effect is generated on the outer edge of the spray, resulting in rolling upward of the droplet at the end of the spray with the gas flow, and the higher the back pressure, the more indistinct the boundary of the spray end. After analysis of the spray pressure field and velocity field, it is found that pressure of the inner zone of the spray is lower than the outer zone, which causes the external airflow to impact the spray, thus reducing the spray width and enhancing the interaction, resulting in spray collapse References | Related Articles | Metrics

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Influence of Ethanol-gasoline Blended Fuels on Gasoline Engine Particulate Emission During Start Yuan Chao, Hong Wei, Su Yan, Xie Fangxi, Chen Jing 2018, 40 (12):  1393-1397.  doi: 10.19562/j.chinasae.qcgc.2018.012.003 Abstract ( 341 )   PDF (901KB) ( 306 )   Save In order to investigate the effect of ethanol addition on gasoline direct injection engine particulate emission during the starting period, E10 and E20 fuels are obtained by blending 10% and 20% volume fraction ethanol fuel into gasoline. With the two fuels and gasoline fuel, study of particulate emission from GDI engine during the starting period is conducted. It is found that particle number concentration increases dramatically during the first 10 seconds of the initial starting period with each fuel, which is due to increase of both nuclear mode and accumulated mode particles. The particulate emission is dominated by nuclear mode particles. As the temperature of the coolant increases, the amount of accumulated particles decreases dramatically. Adding a certain amount of ethanol to gasoline can improve the emission of nuclear mode particles under the start condition. The total concentration of particulates reduces by 37.8% and 64.5% during 40s starting period respectively, at 20 and 80℃ with E20 fuel. References | Related Articles | Metrics

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An Experimental Study on the Influence of RPA on High-Altitude Region Emission Characteristic of RDE Test for PFI Light Gasoline Vehicle Cheng Liang, Xu Zhiyin, Wu Jianhua, Qiu Xiaowei, Xie Xijun 2018, 40 (12):  1398-1404.  doi: 10.19562/j.chinasae.qcgc.2018.012.004 Abstract ( 540 )   PDF (1767KB) ( 363 )   Save To explore the influence of RPA (Relative Positive Acceleration) factor on emission characteristics of PFI (Port Fuel Injection ) gasoline vehicles in the RDE (Real Driving Emission) test, RDE emission tests are carried out on an electronically controlled inlet multi-point injection gasoline vehicle using the AVL-M.O.V.E. PEMS(Portable Emission Measurement System)under gentle, normal and intense driving behaviors in Xining high-altitude region respectively, and the gasoline engine is not modified during the tests. The results show that the driving behaviors of different RPA values which are within a large range according to the national standard directly affect the results of the RDE emission test. The cold starting stage of RDE test has great influence on PN and CO emission, with greater influence on PN than on gas pollutants. The variation of CO and PN emission with RPA value is not obvious; however, NOx and CO2 emissions are positively correlated with RPA values. CF (NOx)>CF (CO)>CF(PN), and the change amplitude of CF (NOx) is significantly increased with the increase of RPA value, thus NOx emission should be paid attention to during RDE test under the plateau condition. The RPA affects the distribution of CO2 emission on the characteristic curve. The larger the RPA value, the closer distribution of CO2 emission on the characteristics curve to the upper tolerance References | Related Articles | Metrics

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Adaptive Sliding Mode Control for Vehicle Series-Parallel Electrophoretic Coating Conveyer Based on Time-delay Estimation Gao Guoqin, Zhou Huihui, Fang Zhiming 2018, 40 (12):  1405-1412.  doi: 10.19562/j.chinasae.qcgc.2018.012.005 Abstract ( 212 )   PDF (1343KB) ( 279 )   Save Time-delay estimation technique is adopted to set up a dynamic model for a novel series-parallel vehicle electrophoretic coating conveyer, which can fully reflect its dynamic characteristics and fulfill real-time control. Then, for solving the problems of system uncertainty and time-delay estimation error, sliding mode control strategy is introduced, and for improving the tracking performance of system and effectively weakening the chattering caused by sliding mode control, an adaptive rule is introduced, which can adjust the magnitude of sliding mode switching gain and change its adjusting rate, and hence a time-delay estimation-based adaptive sliding mode control without upper-bound information of uncertain system is proposed, with its stability validated by Lyapunov stability theory. Finally a contrastive simulation on the adaptive sliding mode control with time-delay estimation and that without changing the adjusting rate of sliding mode switching gain is conducted by MATLAB and verified by test on prototype. The results show that the proposed adaptive sliding mode control with time-delay estimation achieve better tracking performance without upper-bound information of uncertain system, and effectively weaken the sliding mode control-induced chattering. Related Articles | Metrics

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A Study on ‘Breathing Effect’ of Traction Batteries for Electric Vehicles Xu Chengshan, Lu Languang, Ouyang Minggao, Jiang Fachao 2018, 40 (12):  1413-1417.  doi: 10.19562/j.chinasae.qcgc.2018.012.006 Abstract ( 419 )   PDF (1577KB) ( 648 )   Save ‘Breathing effect’ appearing in vehicle lithium traction battery during its charge and discharge due to the intercalation and de-intercalation of lithium ion is greatly affected by electrode material, ambient temperature and charging and discharging current rates as well as the battery state of health. In this paper, a test rig for measuring the thickness of a Li-ion battery is designed and built to study the ‘breathing effect’ of battery under different current rates and temperatures. The results show that the higher current rate and lower temperature result in the weaker breathing effect of battery. References | Related Articles | Metrics

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Parameter Identification of Lithium Battery Model Based on Simulated Annealing Algorithm Luo Yong, Qi Pengwei, Kan Yingzhe, Li Peiran, Liu Li, Cui Huanyu 2018, 40 (12):  1418-1425.  doi: 10.19562/j.chinasae.qcgc.2018.012.007 Abstract ( 321 )   PDF (1636KB) ( 570 )   Save In order to set up an accurate battery model for precisely estimating its state of charge (SOC), the charge and discharge characteristics of lithium battery under different currents and SOCs are obtained by test, and the parameters R and C of battery under the same conditions are identified in this paper. In view of the features of parameter identification, i.e. unknown initial values, massive data processing and being prone to fall into local optimum, simulated annealing algorithm, which can rapidly converged to the global optimum without initial parameters, is adopted to identify the parameters R and C of battery. Simulation and test results show that the battery model established by the above method has relatively high accuracy. References | Related Articles | Metrics

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A Design Method of Car Body Stiffness Chain Based on Crashworthiness Guo Yi, Liu Zijian, Qin Huan 2018, 40 (12):  1426-1434.  doi: 10.19562/j.chinasae.qcgc.2018.012.008 Abstract ( 258 )   PDF (1992KB) ( 355 )   Save Concurrently considering the dynamic and static stiffness and frontal crash safety, a forward conceptual design method of car body is presented in this paper. Firstly according to class A surface and vehicle general layout, a simplified geometric model for car body is established, 19 main cross-sections of the body is determined, and the stiffness chain model of car body is built based on beam element theory and transfer matrix method. Then rectangular front longitudinal beam is designed by using collision empirical formula, the frontal crash dynamic loading of car body is simulated by equivalent static load, and the requirements of car body deformation are put forward based on equivalent static loading condition. Next, a simulation on the main cross-section parameters of each beam element of car body is conducted by using genetic algorithm, with minimizing car body mass as objective and the static stiffness, the first order mode and collision deformation of car body as constraints. Finally, a finite element simulation is performed on an approximate benchmark car, with its static stiffness and vibration modes of car body calculated and compared with that by using stiffness chain method, verifying the feasibility of the method adopted. References | Related Articles | Metrics

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A Research on Test Scenes of Two-wheeled Vehicles for Automatic Emergency Braking System Based on Real Accident Cases Hu Lin, Yi Ping, Huang Jing, Zhang Xin, Lei Zhengbao 2018, 40 (12):  1435-1446.  doi: 10.19562/j.chinasae.qcgc.2018.012.009 Abstract ( 543 )   PDF (778KB) ( 448 )   Save Two-wheeler accident is an important type of road traffic accidents in China. However, China lacks suitable two-wheeler test scenes in automatic emergency braking (AEB) system research. In view of this, two-wheeler test scenes for AEB system adapted to road traffic environment in China are established in this paper by taking references from existing research outcomes in the world. Firstly, a cluster analysis on 419 cases of car-to-two-wheeler crash accidents is conducted, and 11 typical types of car-to-two-wheeler crash accident scenes are obtained. Then, according to the severity of accident casualty and the number of accident samples under different parameter features of 11 types of scenes, the detailed parameter features of two-wheeler motion states, the speed of car and two-wheelers in all types of scenes are accurately obtained. Finally, a main test scene with the car straightly passing through intersection under good lighting condition is designed, and through the variation of the main test scene, another 5 types of secondary test scenes are obtained, and hence in the end, the specific parameter features of altogether 6 types of two-wheeler test scenes (main test scene plus 5 secondary test scenes) for AEB system under the conditions of car crashing with three different two-wheelers (two-wheeled electric vehicle, motorcycle and bicycle) are given. The findings of this study can provide a reference basis for the research of two-wheeler test for AEB system in China. References | Related Articles | Metrics

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A Study on Control Strategy of Vehicle in Creep Ma Biao, Chang He, Li Heyan, Li Huizhu, Zhu Li'an 2018, 40 (12):  1447-1453.  doi: 10.19562/j.chinasae.qcgc.2018.012.010 Abstract ( 381 )   PDF (1166KB) ( 435 )   Save To solve the problems of velocity fluctuation and overheat of friction pair during creep, an analysis on friction characteristics of dry friction pair is conducted and the heat safety boundary is determined. A dynamic powertrain system model is established, and a start control strategy is obtained which meets the jerk requirement and have small velocity overshoot compared with target velocity 3km/h by considering variation of friction coefficient when vehicle is starting and in process of creep. Taking the minimum deviation between the actual speed and the target speed as the control objective, the clutch compression force is adjusted by PID to keep the vehicle speed stable during creeping, and the creeping control strategy is formulated to ensure thermo-safety of clutch in creep References | Related Articles | Metrics

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EPS Friction Compensation with Adaptive Neural Network Based on Back-stepping Method Zhao Linfeng, Shao Wenbin, Xu Feiyang, Chen Wuwei 2018, 40 (12):  1454-1460.  doi: 10.19562/j.chinasae.qcgc.2018.012.011 Abstract ( 256 )   PDF (1107KB) ( 280 )   Save In order to eliminate the effects of individual difference in friction torque of EPS system caused by manufacturing and assembling process, firstly an EPS dynamic model is established, and with consideration of the uncertainty, nonlinearity and individual difference of friction in steering system, a friction model for steering system is established based on LuGre model and a friction state observer is designed. Then an adaptive neural network control strategy based on back-stepping method is proposed to compensate the friction in EPS system, and its stability is proved by Lyapunov stability theorem. Finally, the results of simulation and hardware-in-the-loop test show that with adaptive neural network control strategy, motor current tracing performance is improved, and after friction compensation, the handiness and returnability of EPS are further enhanced and the fluctuation of friction torque, caused by the uncertainty of friction and the individual difference of EPS products is suppressed to certain extent References | Related Articles | Metrics

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Analysis on the Transfer Characteristics of Vehicle Structure-borne Noise and the Cause of Its Peak Noise Wang Yongliang, Liu Hao, Zheng Qingqing, Luo Ting, Xu Yanping, Deng Feng, Zhou Quan, Zhou Fuquan 2018, 40 (12):  1461-1466.  doi: 10.19562/j.chinasae.qcgc.2018.012.012 Abstract ( 653 )   PDF (1999KB) ( 414 )   Save The transfer characteristics of structure-borne noise and the cause of its peak noise of vehicle body in engine idle condition are analyzed in this paper. Hammer impact is used to measure the noise transfer function (NTF) from the acceleration of passive side of engine mounts to the right ear of driver,and the transfer function from acceleration to sound pressure is deduced. Then based on the acceleration excitation of passive side of engine mounts in engine idle condition, the total sound pressure at driver's right ear is accurately composed and the contribution of path transmission noise is investigated. The results show that the total sound pressure is the superposition of transfer sound pressures of all paths in frequency domain, which are related to both amplitudes and phases, and the path transfer pressures have both positive and negative contributions to the total sound pressure. Finally the main paths of sound transmission are identified,and the dynamic stiffness curves, the noise transfer function curves and the acceleration spectrum of engine mounts are used to analyze the cause of peak noise of all paths. References | Related Articles | Metrics

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Simulation Analysis and Experimental Verification of Transmission Shaft Optimization Based on Automobile NVH Improvement Xu Jingli, Pan Qinggu, Chen Duanying 2018, 40 (12):  1467-1474.  doi: 10.19562/j.chinasae.qcgc.2018.012.013 Abstract ( 537 )   PDF (3297KB) ( 448 )   Save Birfield universal joint has the advantages of constant speed transmission and stable additional bending moment. Considering the influence of intermediate support vibration on the transmission shaft power performance and vehicle interior noise, the design scheme of replacing the mid-cross universal joint with Birfield universal joint is proposed. The ADAMS virtual prototype is used to simulate the three-cross-shaft universal joint drive shaft and Birfield universal joint drive shaft under different input speed and different angle between the spindle shafts. The analysis shows that the vibration acceleration and torque fluctuation of the intermediate support of Birfield universal joint drive shaft tend to be more stable. Comparison and analysis of vehicle interior noise experiments are carried out on cars with the two kinds of transmission shaft. The results show that Birfield universal joint can effectively improve vehicle interior noise, which is about 5dB lower than that of the cross shaft universal joint transmission shaft in the middle and low speed areas, and improves the NVH performance of the vehicle. References | Related Articles | Metrics

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An Optimization of Vehicle Rear-view Mirror and Wiper Wind Noise Hou Zhaoping, Fu Nian, Huang Yuanyi, Xu Tie, Chen Ruifeng, Shen Yantao 2018, 40 (12):  1475-1479.  doi: 10.19562/j.chinasae.qcgc.2018.012.014 Abstract ( 755 )   PDF (2226KB) ( 394 )   Save The external flow field and the interior noise of the passenger compartment of a SUV are calculated by computational fluid dynamics and statistical energy method respectively, and the sound pressure level (SPL) curve at drivers head region is obtained. Based on the simulation results of original vehicle model, rear view mirror and wiper are modified, and the noise evaluation and comparison between before and after modifications are carried out by numerical simulation and road test. The SPL curves obtained by simulation and road test have the same overall tendency, showing the effectiveness of simulation results. The results of simulation indicate that both rear-view mirror and wiper modification schemes have noise reduction effects in full frequency range, in which the maximum reduction amplitude in SPL reaches 5.6dB(A) and the total SPL with both schemes reduce by 1.5 and 1.8dB(A) respectively. The results of road test show that in high frequency segment with relatively low noise, the SPL after modification has apparent fall, with the maximum reduction amplitude reaching 5.1dB(A) in some high-frequency band. And the total SPL with both modification schemes reduce by 0.2 and 0.7dB(A) respectively, demonstrating the effectiveness of modifications and the feasibility of study method. References | Related Articles | Metrics

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Simulation and Experimental Study on Aerodynamic Noise of Automotive Rear-view Mirror Wang Jun, Cheng Ruyi, Yang Jianguo, Gong Xu, Li Lin 2018, 40 (12):  1480-1487.  doi: 10.19562/j.chinasae.qcgc.2018.012.015 Abstract ( 545 )   PDF (2123KB) ( 465 )   Save The accuracy of overall flow simulation on original design is determined according to the comparison between calculation and wind-tunnel test results of the aerodynamic performance parameters of vehicle model under two different states (with air inlet grill opened or closed), while the accuracy of aerodynamic noise simulation with a grid size of 2mm is obtained based on the comparison between the calculation result of the sound pressure level of tested points on side window surface using DES method and test results. The flow visualization of new scheme and original design using Q-criterion shows that the flow state of wake flow region of new rear-view mirror is improved. The comparison of the turbulent pressure fluctuation on side window surface shows that the influence of shape change of rear-view mirror is trivial, while the sound pressure fluctuation obtained by Lighthill acoustic analogy method has a significant difference, the sound pressure fluctuation of new scheme in the range of 2000~8000Hz is obviously reduced. The sound source distribution and improvement effects of Beamforming test are consistent with CFD calculation predictions and have a very good correlation with the interior sound pressure level test. The above studies show that Q-criteria flow visualization can be applied to the quantitative evaluation of aerodynamic noise, and the sound pressure fluctuation is the most important evaluation measure for the aerodynamic noise simulation of rear-view mirror and should not be ignored. References | Related Articles | Metrics

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Optimization of Lubrication Characteristics of Bearings Based on Global Sensitivity Analysis and Optimization Algorithm of PE-HMGE Li Linjie, Wei Jingsi, He Zhiliang, Chen Yu, Zhan Wenfeng 2018, 40 (12):  1488-1493.  doi: 10.19562/j.chinasae.qcgc.2018.012.016 Abstract ( 345 )   PDF (745KB) ( 338 )   Save Multi-parameter optimization design of complex nonlinear system involves huge computational work, and the optimal solution in theory is difficult to obtain. A new multi-parameter and multi-objective optimization strategy that combines the global sensitivity analysis with optimization algorithm of PE-HMGE is proposed. By using the variance-based Sobol global sensitivity analysis, the complex system model is simplified, and the sensitivity parameters are defined to construct the multi-objective optimization model and the optimal solution is obtained by using the optimization algorithm of PE-HMGE. This method is used for simplified model optimization design of lubrication characteristics of main bearings. According to the compared simulation results, the minimum oil film thickness improves by 39%; the peak asperity contact pressure and the average friction power loss decreases by 45% and 19% respectively. The experimental results show that lubrication characteristics of bearings are greatly improved, which has proved the validity of the proposed new method References | Related Articles | Metrics

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Driving Trajectory Curvature Prediction of Vehicle on Highway Based on End-to-end Learning Mechanism Jiao Xinyu, Yang Diange, Jiang Kun, Cao Zhong, Xie Shichao, Wang Sijia 2018, 40 (12):  1494-1499.  doi: 10.19562/j.chinasae.qcgc.2018.012.017 Abstract ( 417 )   PDF (1125KB) ( 434 )   Save The driving trajectory of vehicle on highway is predicted based on end-to-end learning mechanism in this paper. Firstly for quantitatively express the driving trajectory of vehicle and reasonably evaluating prediction results, a model along with an evaluation system for driving trajectory curvature prediction are established. Then in view of the problem of poor performance of end-to-end-based driving trajectory curvature prediction caused by the uncertainty of driver's behavior decision in training set, an optimization is conducted by using scene segmentation and feature pre-extraction techniques,which is verified by real vehicle test. The results show that the method adopted enhances the accuracy and reliability of driving trajectory prediction on highway References | Related Articles | Metrics