Table of Content

25 October 2018, Volume 40 Issue 10 Previous Issue    Next Issue

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A Study on Power-torque-efficiency Three-parameter Matching Method for Series-Parallel Hybrid Electric SystemZeng Xiaohua, Wang Zhenwei, Song Dafeng, Ba Te, Yang Nannan, Chen Huiyong, Wang Yinshu 2018, 40 (10):  1125-1131.  doi: 10.19562/j.chinasae.qcgc.2018.010.001 Abstract ( 815 )   PDF (1019KB) ( 1647 )   Save A three parameter (power, torque and efficiency) matching method is proposed for series-parallel hybrid electric system. With consideration of the configuration features and power performance design requirements of series-parallel hybrid electric system and taking maximizing system efficiency as objective, the method uses the preset control algorithm to predict the distribution of target operating points and energy demand of power sources, with the selection of key components of the whole system determined. The validity of the matching method proposed is verified by CRUISE / Simulink modeling and simulation. References | Related Articles | Metrics

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Torque Coordinated Control During Mode Switching of a Compound Power-Split Hybrid System Based on Reference Model Zhao Zhiguo, Jiang Lanxing, Li Mengna, Wang Maoyao 2018, 40 (10):  1132-1138.  doi: 10.19562/j.chinasae.qcgc.2018.010.002 Abstract ( 245 )   PDF (1331KB) ( 341 )   Save Aiming at the problem of poor ride comfort in a compound power-split hybrid system with double-row planetary gear sets during switching between pure electric and e-CVT modes, a torque coordinated control strategy is proposed. A system dynamics analysis is conducted and a dynamics model for mode switching is established. The strategies of torque assignment and jerk compensation control are devised based on reference model, the torques of different power sources in different stages are dynamically assigned, and the changing rate of motor torque is adjusted according to the target of ride comfort to compensate the torque fluctuation of hybrid system. The results of simulation and bench test show that the strategy proposed can meet the requirements of the power performance and startability of vehicle in mode switching process with the jerk being lowered to below 15.5m/s3, meeting the requirements of national standard References | Related Articles | Metrics

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A Research on the Real Driving Emission Characteristics of Hybrid Electric Vehicles Yu Wenlin, Ge Yunshan, Wang Xin, Peng Zihang, Wang Xuezhi, Yin Hang 2018, 40 (10):  1139-1145.  doi: 10.19562/j.chinasae.qcgc.2018.010.003 Abstract ( 248 )   PDF (2384KB) ( 386 )   Save Hybrid electric vehicles have the advantages of good fuel economy and low emissions compared with traditional fuel vehicles, so they become the focus of research in present automotive field. Recently promulgated China-VI light-duty vehicle emission regulation introduces real driving emission (RDE) test from European standard. Based on the requirements of the regulation, three hybrid electric vehicles (HEVs) and three gasoline vehicles with same displacement are selected to conduct RDE test, with the pollutant emission characteristics of HEVs analyzed and some suggestions for further improvements of current RDE regulation given. References | Related Articles | Metrics

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Effect of Driving Pattern on RDE of Vehicle Equipped with a Port Fuel Injection Gasoline Engine Wang Xiaowei, Yan Yan, Jing Xiaojun, Dai Chunbei, Yan Feng 2018, 40 (10):  1146-1150.  doi: 10.19562/j.chinasae.qcgc.2018.010.004 Abstract ( 229 )   PDF (1485KB) ( 424 )   Save Real driving emission (RDE) tests are conducted by using a portable emission measurement system (PEMs) for a light duty gasoline vehicle equipped with a natural aspiration and port fuel injection (PFI) engine in accordance with China Ⅵ emission regulation of light-duty vehicles and moderate driving and dynamic driving are defined based on trip dynamics. Results show that NOx and PN emissions exhibit a small difference between dynamic driving and moderate driving, but the CO emission for dynamic driving is 84 times and 75 times of that for moderate driving in city trip and total trip respectively. Frequent acceleration and deceleration of dynamic driving is the major reason for drastic increase of CO emission. CO emission is proportional to the acceleration in the city trip. And the bad emission calibration for the high speed and high load condition may be responsible for the high CO emission in the motorway trip. References | Related Articles | Metrics

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Estimation of Vehicle Instantaneous Fuel Consumption Based on Least Square Method Zhang Jinhui, Li Keqiang, Xu Biao, Li Hong 2018, 40 (10):  1151-1157.  doi: 10.19562/j.chinasae.qcgc.2018.010.005 Abstract ( 310 )   PDF (2074KB) ( 435 )   Save Accurate estimation of vehicle transient fuel consumption is a fundamental part of the energy-saving control. For the steady-state fuel consumption model, it is affected by many factors such as the non-linear working characteristic of the engine, driving habits, driving environment, driving state, vehicle load etc. The transient fuel consumption calculated by the model deviates greatly from the actual fuel consumption. For the existing transient fuel consumption model, the parameters are difficult to calibrate. Therefore, a new model utilizing vehicle speed and acceleration is built to estimate the instantaneous fuel consumption, and the least square method is employed to identity the parameters in this new model. In order to lower estimation error of the transient fuel consumption, exponential attenuation factor is added into the least square method, i.e. the least square method with exponential attenuation factor is utilized to identify the parameters of the new fuel consumption model. The effectiveness of the new fuel consumption estimation model is tested experimentally. The result shows that the new fuel consumption model based on the least square can estimate transient fuel consumption accurately, and that the fuel consumption model by the least square method with exponential attenuation factor produces lower estimation error and its estimation accuracy is hardly affected by the factors such as the driving state of the vehicle, the road environment, etc References | Related Articles | Metrics

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The Search for Sensitive Factors and the Optimization on Restraint System in Car-to-car Oblique Crash Yan Lingbo, Zhang Chao, Xu Wei, Cao Libo, Dai Hongliang 2018, 40 (10):  1158-1165.  doi: 10.19562/j.chinasae.qcgc.2018.010.006 Abstract ( 225 )   PDF (1561KB) ( 359 )   Save To find the parameters of occupant restraint system having significant effects on car-to-car oblique crash, the models for driver's restraint system of SUV,mid-size car and compact car are created. The uniform Latin hypercube sampling is used for the design of experiment and T-test is utilized to get the sensitive factor of different types of vehicle in car-to-car oblique crash, based on which an optimization is conducted on restraint system with consideration of crash compatibility. The results show that the sensitive factors for three types of vehicle are roughly the same in car-to-car oblique crash. Compared with the optimization on each vehicle separately, the optimization with minimizing the sum of WIC value of both vehicles involved in crash as objective can not only effectively reduce the injury values of both vehicles, but also get better crash compatibility. Although the optimization trends of restraint system parameters for different vehicles are different, there are still some common features, i.e. optimization tends to increase the mass flow of airbag and reduce the force limit of seatbelt References | Related Articles | Metrics

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Optimization Design of Vehicle CFRP B-pillar Stiffening Panel for Crashworthiness Zhang Junyuan, Jiang Zhe, Li Zhongyu, Zhao Zijian 2018, 40 (10):  1166-1171.  doi: 10.19562/j.chinasae.qcgc.2018.010.007 Abstract ( 310 )   PDF (2015KB) ( 534 )   Save With the consideration of the characteristics of carbon fiber reinforced polymer (CFRP) composite, the original steel stiffening panel of B-pillar is substituted with CFRP, with the laminate optimized. Firstly on the basis of vehicle finite element model for side impact, the substructure model for B-pillar is decoupled, the dynamic model for substructure is used to conduct the material substitution and performance calculation of B-pillar stiffening panel, and the initial layup and thickness of the laminate are determined. Then to give full play to the advantage of designability of composites, the structural optimization method for composite is adopted to optimize the ply thickness, angle, and layup sequence of laminate. Compared with original vehicle structure, the CFRP stiffening panel of B-pillar achieves a significant lightweighting results with its crashworthiness remained unchanged References | Related Articles | Metrics

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Comparison of Adaptive Decomposition Methods for Diesel Engine Vibration Signals Jia Jide, Ren Gang, Jia Xiangyu, Han Jiajia 2018, 40 (10):  1172-1178.  doi: 10.19562/j.chinasae.qcgc.2018.010.008 Abstract ( 242 )   PDF (1101KB) ( 308 )   Save Variational mode decomposition (VMD) is a new adaptive decomposition method. In order to check its suitability for diesel engine signals, a multi-component, AM-FM simulation signal is built with white noise added, which is then decomposed by using VMD and compared with other adaptive decomposition methods in terms of decomposition effects and the capability to suppress modal aliasing and endpoint effects. Then, the vibration signals of diesel engine under transient conditions are decomposed, the changing pattern of wear signals of crankshaft bearing is explored and fault features are extracted. Finally fault types are identified by using support vector machine, to further verify the effectiveness of the method adopted. The results show that VMD method is better than other adaptive decomposition methods in decomposition results and the capability to suppress modal aliasing and endpoint effects, suitable for the state monitoring and fault diagnosis of diesel engine References | Related Articles | Metrics

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Objective Evaluation of Vehicle Interior Aerodynamic Noise He Yinzhi, Lu Chunyang, Wu Yu, Yang Zhigang 2018, 40 (10):  1179-1184.  doi: 10.19562/j.chinasae.qcgc.2018.010.009 Abstract ( 255 )   PDF (1635KB) ( 431 )   Save Wind tunnel tests on the aerodynamic acoustics of a vehicle are carried out to study the change of interior aerodynamic noise, evaluated by A-weighted sound pressure level (SPL), loudness and articulation index (AI) three indicators respectively, under different wind speeds and yaw angles and the effects of rearview mirror sealing and wiper on interior noise. The results show that the frequency spectrum characteristics of interior aerodynamic noise under different wind speeds are similar. As wind speed goes up, the A-weighted overall SPL and loudness of interior noise increase almost linearly, and AI linearly decreases, while with the increase of absolute value of yaw angle, the interior A-weighted overall SPL and loudness rise and AI lowers, but with a less obvious linearity of rise and fall. In addition, the rearview mirror sealing has larger influence on interior noise at middle-high frequency range (500Hz-3kHz), while the effects of wiper are mainly at high frequency band (3kHz-6.3kHz). From the numerical point of view in analyzing the influences of both rearview mirror sealing and wiper on interior aerodynamic noise, AI always more sensitive than A-weighted SPL and loudness References | Related Articles | Metrics

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Effects of Driver's Braking Intention on Hysteresis Characteristics of Emergency Braking in Multi-axle Vehicle Wang Zhe, Zhou Xiaojun, Yang Chenlong, Hu Bo 2018, 40 (10):  1185-1191.  doi: 10.19562/j.chinasae.qcgc.2018.010.010 Abstract ( 215 )   PDF (1806KB) ( 370 )   Save The travel and velocity of brake pedal, as the executive element of driver's braking intention, may change the characteristics of pneumatic braking system, and the hysteresis effects of brake seriously affect the performance of emergency braking. In this paper, a test bench for the pneumatic braking system of an 8-axle vehicle is constructed based on the composition of pneumatic braking system in multi-axle vehicle and the dynamic modeling analysis on its components. The quick-response servo driving mechanism is adopted to control the travel and velocity of brake pedal for achieving accurate simulation on driver's different emergency braking intentions. Test results show that circuit hysteresis time extends with the increase of brake pedal travel, exhibiting a relation of quadric curve, and it shortens with the rise of brake pedal velocity. In addition, a 1st-order hysteresis model for each circuit of pneumatic braking system in multi-axle vehicle is established by using system identification method with consideration of driver's braking intention References | Related Articles | Metrics

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A Study on Key Issues of Micro-Slip Control for Wet Dual-clutch Bao Wei, Ge Jianjun, Xiao Xu, Cao Jiang 2018, 40 (10):  1192-1199.  doi: 10.19562/j.chinasae.qcgc.2018.010.011 Abstract ( 258 )   PDF (1326KB) ( 560 )   Save In order to enhance the driving quality of wet dual-clutch vehicle, the key issues of micro-slip control (MSC) of wet dual-clutch are studied. Firstly, the effects of micro-slip on clutch damping are analyzed, and a mathematical model for the controlled object is created. On this basis, a current/micro-slip double closed-loop structure of clutch MSC system is proposed and the design methods of current controller and micro-slip controller are investigated. Then real vehicle test is conducted to verify the accuracy of current/micro-slip double closed-loop control scheme and the effectiveness of MSC in attenuating the vibration transferred from engine. Finally clutch cooling test is performed to get the desired flow rate and outlet temperature of clutch coolant, based on which the optimal amounts of clutch micro-slip under different engine speeds and transmission fluid temperatures are determined. The results of the study indicate that it is a practical and feasible approach by applying MSC to enhance the driving quality of wet dual-clutch vehicle References | Related Articles | Metrics

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A Research on Lock-up Process Control Strategy for Torque Converter Based on Dual Objectives Li Chunfu, Xi Junqiang, Gu Hongtao, Chen Huiyan 2018, 40 (10):  1200-1205.  doi: 10.19562/j.chinasae.qcgc.2018.010.012 Abstract ( 216 )   PDF (1072KB) ( 214 )   Save In order to take into account the requirements of both jerk and slipping work of torque converter in lock-up process, the vehicle dynamics model in torque converter lock-up process is set up, with the formulae of jerk, slip time and slipping work in lock-up process derived. Then taking a heavy-duty vehicle as an example, a simulation is conducted to obtain the jerk curve in a lock-up process with engine running in a constant deceleration condition. The results show that the jerk is much smaller than the standard limits and it is found by calculation and analysis that in the lock-up process with the engine decelerating with a constant rate, the reasonable values of clutch pressure coefficient are in a range of 1.05 and 1.2 with a slipping time of around 1s. Finally according to the results of simulation, a control strategy for lock-up process is put forward based on the target trajectory of engine speed, with its feasibility verified by real vehicle test. This study provides an effective strategy for clutch engagement control with concurrently considering the requirements of both jerk and slipping work References | Related Articles | Metrics

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Steering Performance Optimization of an In-wheel Motor Drive Electric Vehicle Zhang Zhiyong, Zhang Feng, Huang Caixia, Liu Xin 2018, 40 (10):  1206-1214.  doi: 10.19562/j.chinasae.qcgc.2018.010.013 Abstract ( 209 )   PDF (1762KB) ( 461 )   Save Aiming at the adverse effects of in-wheel-motor on the design of front suspension structure and vehicle handling stability, the design of front suspension structure and parameters optimization are carried out. Firstly a steering knuckle structure suitable for the front suspension of in-wheel-motor drive vehicle is designed within available space and the coordinates of key hard-points are preliminarily determined. Then with steering handiness as optimization objective and steering returnability as constraint, an optimization model for wheel alignment parameters is established and a parameter optimization is conducted on the hard-points coordinates of steering knuckle by using integrated platform of Isight and Adams/Car. Finally both numerical simulation and real vehicle test are performed on steering handiness and returnability. The results show that after optimization the overall steering performances of vehicle are obviously improved References | Related Articles | Metrics

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Multi-mode Switching Control for Robot Driven Vehicles Wu Jun, Chen Gang 2018, 40 (10):  1215-1222.  doi: 10.19562/j.chinasae.qcgc.2018.010.014 Abstract ( 203 )   PDF (1772KB) ( 264 )   Save In order to realize the accurate speed and trajectory tracking under different driving conditions, a multi-mode switching control method for robot driven vehicle is proposed. Through analyzing the manipulation of robot driver on the movements of pedals and steering wheel in an automatic transmission vehicle, the kinematic models of the mechanical legs for acceleration and braking and the mechanical manipulator for steering wheel of robot driver and the longitudinal and lateral kinetic models of vehicle are established. On this basis, the switching controllers for acceleration and braking mechanical legs, fuzzy PID/fuzzy PID+Bang-Bang speed switching controller and fuzzy PID/fuzzy PID+Bang-Bang steering switching controller are designed. In them, the switching controllers for acceleration and braking mechanical legs take target vehicle acceleration as switching rule to achieve coordinated control of acceleration and braking mechanical legs, the speed switching controller takes speed error as the criteria for the mode decision making of Bang-Bang controller and the input of fuzzy PID controller, while the steering switching controller takes the lateral error of trajectory tracking as the mode decision making input of Bang-Bang controller and takes the yaw rate difference between current and next control moment as the input of fuzzy PID controller. The results of simulation and test verify the effectiveness of the method proposed References | Related Articles | Metrics

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Optimal Path Programming Algorithm with Consideration of Signalized Intersection Delay Hu Lin, Zhong Yuanxing, Huang Jing, Du Ronghua, Zhang Xin 2018, 40 (10):  1223-1229.  doi: 10.19562/j.chinasae.qcgc.2018.010.015 Abstract ( 231 )   PDF (1255KB) ( 486 )   Save An optimum path programming algorithm is proposed in this paper with consideration of waiting time at signalized intersections. Firstly through the collection of floating vehicle data by GPS and matching with electronic map, the average vehicle speed and traveling time at each road section are calculated real time. Then the probability model of traffic lights at intersections is constructed based on Markov chain, and by adopting vehicle-to-infrastructure communication technique, the position and phase timing information of traffic lights at each intersection are obtained in advance and the vehicle speed is optimized when vehicle is approaching intersection. Next, vehicle runs through the intersection in acceleration is considered as an extension of green phase, with which the waiting time model of vehicle fast passing through intersection is constructed, and based on this and A* algorithm, an improved A* algorithm is put forward. Finally a simulation is conducted with a road network in Changsha city as an example, and the results show that the travel time from starting point to destination obtained with the improved A* algorithm is obviously shorter than that with traditional A* algorithm References | Related Articles | Metrics

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A Study on the External Flow Field Characteristics of Vehicle Windshield and Their Effects on Rain Droplet Motion Jiang Libiao, Qiu Huachuan 2018, 40 (10):  1230-1238.  doi: 10.19562/j.chinasae.qcgc.2018.010.016 Abstract ( 318 )   PDF (7183KB) ( 241 )   Save A numerical simulation is conducted on the external flow field characteristics of windshield in this paper for revealing their effects on rain droplet movement. Firstly standard k-ε turbulence model is used to set up the calculation region of windshield model and generate its mesh control region. The airflow model of external flow field of windshield is established with boundary conditions set and hybrid mesh used for key regions. Then CFD software COMSOL Multiphysics is adopted to perform numerical simulation on air flow model for analyzing the characteristics of pressure distribution and attached airflow velocity on the external surface of windshield. . The results of experiment show that the simulated characteristics of attached airflow on windshield surface are basically in accordance with experiment results, verifying the effectiveness of the model built. Next, control variable scheme is utilized to simulate the effects of the airflow velocity on and the inclined angle of windshield on its flow field characteristics. The results indicate that the change of airflow velocity affects only the values of surface pressure and attached airflow velocity, but not the patterns of pressure distribution and attached airflow direction on windshield surface, while the inclined angle of windshield has larger effects on external flow field. With the reduction of windshield inclined angle, the velocities of attached airflow tends to be more uniform. Finally, the effects of different airflow velocities on the movement of rain droplets are studied with a result providing an important reference value and guiding significance for the control of rain droplet motion. References | Related Articles | Metrics

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A Study on Flow Characteristics of Back Pressure Chamber Under Off-design Conditions of Electric Vehicle Air Conditioning Liu Xingwang, Wan Chunhuan 2018, 40 (10):  1239-1245.  doi: 10.19562/j.chinasae.qcgc.2018.010.017 Abstract ( 405 )   PDF (2179KB) ( 448 )   Save In view of complex and changeable characteristics of operating conditions of electric vehicle A/C system, research is conducted on the performance of back pressure chamber under off-design conditions of its scroll compressor. In consideration of the influence of balance weight agitation, the flow distribution characteristics of the back pressure chamber with different inlet pressure under variable operating conditions is simulated by FLUENT sliding mesh technique. The results show that the flow distribution of the back pressure chamber, the axial balance force and the amount of circulating oil change regularly under variable operating conditions. A new design method is proposed to coordinate the design of the axial balance force and the axial gas force angle position in order to optimize the operation of the orbiting scroll, with the axial force amplitude reduced by 31% References | Related Articles | Metrics

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Design and Verification of Model-based Fault Diagnosis System for Hydraulic Torque Converter Chen Qi, Yao Zhigang, Chen Wuwei, Qadeer Ahmed, Zhang Zhen 2018, 40 (10):  1246-1254.  doi: 10.19562/j.chinasae.qcgc.2018.010.018 Abstract ( 203 )   PDF (1297KB) ( 345 )   Save Hydraulic torque converter (HTC) is an important component that transfers power from engine to gear transmission. In order to overall monitor the working state of HTC and ensure its reliable operation, by applying the theory of fault diagnosis based on structural analysis (SA), fault diagnosis and identification (FDI) system for HTC is designed to detect and locate all the key faults of HTC. Firstly, based on the analysis of the key faults of HTC, the fault model for HTC is established. Next, by means of Dulmage-Mendelsohn decomposition and fault isolability matrix analysis in SA, the fault detectability and fault isolability of HTC are analyzed, indicating that all the 5 key faults of HTC are detectable and isolatable. Then, through the solving of minimal structurally overdetermined sets and based on the theory of analytic redundant relation, the design of FDI system is fulfilled. Finally, the simulation model for FDI system is set up with MATLAB and a simulation is conducted. The results show that the FDI system can detect and isolate all the preset faults, which is consistent with the results of theoretical analysis using SA References | Related Articles | Metrics