Table of Content

25 May 2019, Volume 41 Issue 5 Previous Issue    Next Issue

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A Study on Modified Acceleration-driven DampingControl Strategy for Semi-active Suspension Guo Konghui, Wang Yang 2019, 41 (5):  481-486.  doi: 10.19562/j.chinasae.qcgc.2019.05.001 Abstract ( 478 )   PDF (1879KB) ( 753 )   Save Classical on-off skyhook (SH) control and acceleration-driven damping (ADD) control have their own strong and weak points: the former has better control effects in low-frequency region (in the vicinity of offset frequency of body vibration) while the latter in high-frequency region (higher than offset frequency). For effectively reducing the vibration acceleration of vehicle in whole frequency range, a modified ADD control is proposed, which combines the advantages of both SH and ADD controls, and the above-mentioned control schemes are theoretically analyzed from the angle of phase frequency, verifying the advantage of the algorithm put forward. Finally, both MATLAB/Simulink simulation and hardware-in-the-loop test on a controllable shock absorber are conducted, validating the effectiveness of the algorithm in both time and frequency domains. References | Related Articles | Metrics

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An Experimental Study on the Impact of Lubricant Ash onGasoline Particle Filter Performance of GDI Vehicle Pan Jinchong, Hua Lun, Zhang Wenbin, Lin Yansong, Zhang Yunlong 2019, 41 (5):  487-492.  doi: 10.19562/j.chinasae.qcgc.2019.05.002 Abstract ( 421 )   PDF (2223KB) ( 738 )   Save In order to develop a rapid aging method and to evaluate the durability of GPF, an accelerated ash depostion method of GPF is developed in this study. Based on the accelerated ash deposition method, the effects of GPF ash accumulation on particle emissions, back pressure, and fuel consumption of a GDI vehicle are studied on the engine test bench and the chassis dynamometer. Finally, the ash distribution and composition are analyzed by computed tomography (CT) and x-ray fluorescence (XRF).The test results show that the ash deposition efficiency of the GPF is increasing over time and finally stabilizes at about 30%. The vehicle equipped with GPF can meet CN6 particle emission limits under WLTC test cycle. With the ash accumulation in the GPF, the GPF can maintain its filtration efficiency, which is 82% for PM and 99% for PN. The ash accumulation in the GPF can increase the GPF back pressure, with the maximum value of 6.5 kPa, while it has little influence on the vehicle fuel consumption according to the test results of WLTC test cycle, with the maximum of 1.25%.The ash is mainly composed of CaO and P2O5 at a content of 71.2% of the total mass, which is mainly deposited at the end, especially in the central area of GPF. References | Related Articles | Metrics

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A Research on Ammonia Emission Characteristics of Light-dutyVehicles Based on WLTC and NEDC Cycles Luo Jiaxin, Cui Jianchao, Tan Jianwei, Yang Zhengjun, Zhu Qinggong 2019, 41 (5):  493-498.  doi: 10.19562/j.chinasae.qcgc.2019.05.003 Abstract ( 235 )   PDF (1830KB) ( 368 )   Save Three light-duty gasoline vehicles are selected to conduct the emission tests based on WLTC and NEDC cycles to analyze the emission characteristics of regular pollutants and ammonia. The results show that ammonia is a byproduct of oxidation-reduction reactions, which occur when the initial exhaust of engine enters into three-way catalytic converter (TWC). The main condition for ammonia formation is long-duration acceleration, when relatively high concentration of CO provides a relatively strong reduction environment in TWC, leading to the forming of ammonia. The ammonia emission shows a rising trend as the mileage increases and high CO and ammonia emissions are more likely to occur under low temperature environment. References | Related Articles | Metrics

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A Study on the Influence of Measurement Module on the Measurement ofFlow Through Upper Water Holes on Cylinder Block in a Diesel Engine Dong Qiaoqiao, Huang Rui, Chen Xiaoqiang, Li Jianfeng, Yu Xiaoli 2019, 41 (5):  499-507.  doi: 10.19562/j.chinasae.qcgc.2019.05.004 Abstract ( 212 )   PDF (5281KB) ( 281 )   Save In measuring the flow through the water holes on the upper surface of cylinder block in a diesel engine, the measurement module composed of turbine flowmeter and measuring plates may cause pressure loss in cooling water flow, hence affecting the accuracy of measurement results. In order to study the influence of the measurement module on the flow measurement, test and simulation are carried out in this paper. Firstly, the flow measurement is conducted by using turbine flowmeter and a measuring plate. Then, a 3D CFD simulation is performed on the flow of cooling system with an outcome indicating that the measurement module has a relatively great effect on the results of water flow measurement, with a maximum relative error more than 25%. On the basis of this, the influences of the inner diameter and length of the turbine flowmeter and the water hole structure, hole diameter and depth of the measuring plates on flow measurement are analyzed. Finally, an optimally matched measurement module is obtained, consisting of a turbine flowmeter with an inner diameter of 15mm, a length of 55mm and a measuring plate with a depth of 20mm, a water outlet diameter of 15mm and a cylindrical structure of water hole. The results show that the modified measurement module can effectively improve the accuracy of water flow measurement, with a maximum relative error of only 3.60%. References | Related Articles | Metrics

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Calculation Correction of Fuel Injection Parameters at Different FuelTemperatures of High Pressure Common Rail System Wang Jun, Zhang Youtong, Jin Yi, Han Shu 2019, 41 (5):  508-513.  doi: 10.19562/j.chinasae.qcgc.2019.05.005 Abstract ( 585 )   PDF (1993KB) ( 928 )   Save In order to demonstrate the influence of fuel temperature variation on fuel injection quantity of high pressure common rail system (HPCR), the calculation correction of fuel injection parameters at different temperatures is conducted. Firstly, based on a brief analysis of the characteristic of fuel flow and heat transfer of the HPCR system and according to the working temperature range of diesel engine, a method to determine the reference temperature is put forward. Then, the formula for calculating the corrected quantity of fuel injection quantity and injection pressure is provided by using the method of fluid heat transfer calculation. Finally, combined with real cases, basic MAP of fuel injection pressure and injection quantity under basic temperature is given and corrected MAP of fuel injection pressure and injection quantity is calculated. The results show that the relative error between the calculation and measurement value of fuel injection correction at 50 ℃ is less than 14%, and that between the calculated value and the predicted value at 80 ℃ is less than 9%, which shows the calculation method of fuel injection parameter correction is effective. References | Related Articles | Metrics

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A Research on Handling Stability of High-speed Unmanned Vehicles Liu Kai, Chen Huiyan, Gong Jianwei, Chen Shuping, Zhang Yu 2019, 41 (5):  514-521.  doi: 10.19562/j.chinasae.qcgc.2019.05.006 Abstract ( 553 )   PDF (1578KB) ( 570 )   Save Through analysis of the effect of road adhesion conditions and curvatures to the vehicle steering characteristics and stabilility, an equivalent dynamic model for high-speed unmanned vehicles is established. A model discretization method with variable steps is proposed to ensure a long enough prediction time domain while maintaining model prediction accuracy and computational feasibility. By analyzing the steady running state of high-speed vehicles, the envelope-based sideslip constraints are concluded and the trajectory tracking controller of high-speed unmanned vehicles based on model predictive control is designed. Simulation results validates that the proposed strategy can effectively ensure the vehicle handling stability under different road adhesion conditions and road curvatures. References | Related Articles | Metrics

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Fuzzy Supervisory Control of Mechanical Legs of Unmanned Robots Wang Herong, Chen Gang 2019, 41 (5):  522-529.  doi: 10.19562/j.chinasae.qcgc.2019.05.007 Abstract ( 329 )   PDF (1404KB) ( 458 )   Save To achieve precise control of the leg of a robot driver, a fuzzy supervisory control method is proposed. By kinematic analysis of the throttle /brake pedal of a driving robot manipulated by the mechanical leg, the kinematic relationship of each leg of mechanical legs is described and the Lagrange dynamic model of mechanical legs is established. On this basis, a fuzzy supervisory controller is designed. The stability of tracking error is verified by the principle of Lyapunov stability analysis, and the stability of displacement tracking is ensured. The fuzzy controller takes the displacement tracking error and the rate of error change as input. In the process of displacement tracking, the change trend of tracking error is monitored at all times. When the error does not exceed the given value, the fuzzy controller acts alone; when the error exceeds the given value, the fuzzy supervisory controller is used. Finally, a throttle/brake mechanical leg switch controller is designed, and the speed tracking simulation model of the accelerator/brake leg is built. By comparing the simulation results with the experimental data, the effectiveness of the proposed method is verified. References | Related Articles | Metrics

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Estimation of Excitation Torque Fluctuation and Torsional VibrationPerformance Adjustment of Automobile Transmission System Liu Qiaobin, Shi Wenku, Chen Zhiyong, Gao Chengming, Sun Pan, Xi Guidong 2019, 41 (5):  530-536.  doi: 10.19562/j.chinasae.qcgc.2019.05.008 Abstract ( 429 )   PDF (1326KB) ( 574 )   Save This paper is to study the variation law of engine excitation torque fluctuation coefficient under different driving conditions of the vehicle, and analyze the influence of the key parameters of the transmission system on torsional vibration of the system. Firstly, a simplified lumped mass model of the transmission system and a longitudinal dynamic model of the vehicle are established. Then, the order analysis of the measured torsional vibration data is conducted to determine the main torque excitation order of the transmission system. Furthermore, two intelligent algorithms are introduced to estimate the excitation torque fluctuation coefficient under each gear with the aim to minimize the acceleration time squared error between the measured and simulated values of each WOT condition, and the convergence curves of the two intelligent parameter estimation methods are compared. Finally, with the time domain average speed fluctuation as the evaluation index, the adjustment effect of each main parameter on the torsional vibration is analyzed. The results show that within the test speed, the engine excitation torque fluctuation coefficient decreases with the increase of the speed and load, indicting that the engine runs more smoothly. The conclusion is drawn that proper reduction of clutch stiffness, increase of clutch damping, increase of half-shaft stiffness and damping, increase of flywheel inertia are beneficial to reduce the torsional vibration of the transmission system, thus improving the comfort of the vehicle. References | Related Articles | Metrics

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A Study on Car Drag Reduction by Active and PassiveControl of Complex Underbody Flow Field Yuan Zhiqun, Yang Mingzhi, Zhang Bingrong 2019, 41 (5):  537-544.  doi: 10.19562/j.chinasae.qcgc.2019.05.009 Abstract ( 262 )   PDF (5393KB) ( 603 )   Save In view of the problem existing in the complex flow field structure of car underbody and its effects on fuel economy, with a goal of reducing aerodynamic drag, CFD technique is used to study the active and passive drag reduction methods for the complex flow field of car underbody in sidewind condition,and four drag reduction schemes including spoiler, side-skirts, underbody suction control slot and wake jet flow control slot are designed to analyze the effects of schemes on aerodynamic drag and the mechanism of drag reduction. The results show that the effects of drag reduction is related to yaw angle, spoiler height, the height of side-skirts, the suction speed of underbody control slot and the injection speed and injection angle of wake jet, and the maximum drag reduction of four schemes are 9.4%, 10.4%, 13.5% and 4.7% respectively. During practical use, dynamic control method should be adopted according to vehicle running environment to achieve optimal drag reduction effect. The numerical calculation method is validated by the wind tunnel test on car model. The results of the study provide references for vehicle design. References | Related Articles | Metrics

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Reliability-based Optimization for Vehicle Front Crashwith Probability-interval Mixed Uncertainty Wang Qiong, Huang Zhiliang 2019, 41 (5):  545-549.  doi: 10.19562/j.chinasae.qcgc.2019.05.010 Abstract ( 346 )   PDF (1413KB) ( 340 )   Save Aiming at the problem that the probability distribution functions of some parameters in frontal crash contain uncertain interval variables, a hybrid uncertain reliability-based optimization model for vehicle frontal crash is constructed, and the optimal polynomial model based on error ratio selection technique is introduced to vehicle crash analysis. Due to the existence of interval parameters, the probabilistic constraints in inner layer are established by limiting the lower bound of reliability interval, thus ensuring the safety of body structure. An efficient shifting vector-based decoupling algorithm is adopted, which converts the nested optimization problem into deterministic optimization and sequential iterative process of hybrid reliability analysis, avoiding nested optimization between inner and outer layers, achieving efficient reliability optimization for vehicle frontal crash. The results indicate that after optimization, the total mass of bumper beam, energy-absorbing boxes and front longitudinal beams reduces by 2.4% and all the constraints of reliability indicators have been met, hence realizing the reliability optimization for the safety of vehicle body and occupants while ensuring the lightweighting of vehicle body. References | Related Articles | Metrics

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A Research on the Relationship Between Weight Coefficient Variation ofClutch Optimal Control and the Vehicle Performances Jin Hui, Yu Qian 2019, 41 (5):  550-555.  doi: 10.19562/j.chinasae.qcgc.2019.05.011 Abstract ( 180 )   PDF (1955KB) ( 388 )   Save Clutch control for a vehicle equipped with an automated manual transmission (AMT) during starting process is a multi-objective optimization problem. So the optimal control strategy, based on the minimum cost function of multi-objective constraints, is more suitable for the starting control of AMT vehicles theoretically. However, the weight coefficients in the optimal control strategy are chosen by the designers' subjectivity without definite theories in previous researches. Therefore, the influence of the weight coefficient variation on the starting performance of vehicle is studied in this paper. Firstly, the clutch model is established and the optimal control algorithm is used to design the linear quadratic regulator (LQR), in which the friction time, impact and friction work are selected as vehicle starting optimization indexes. Secondly, according to extreme driving styles, the variation ranges of weight coefficients are determined by analytic hierarchy process (AHP). Finally, the variations of vehicle starting performance indexes when weight coefficients change are investigated and analyzed by a large number of simulation experiments. References | Related Articles | Metrics

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A Research on Modal Analysis and Decoupling-degree Calculation Methodsof Mounting System Under the Influence of Nonlinearity Hu Jinfang, Gao Dongyang, Zhu Dongdong 2019, 41 (5):  556-563.  doi: 10.19562/j.chinasae.qcgc.2019.05.012 Abstract ( 219 )   PDF (2184KB) ( 385 )   Save To study the effects of the excitation amplitude and frequency on the vibration modes of the hydraulic mounting system of powertrain, firstly the amplitude-dependent characteristics of the stiffness of the upper fluid chamber are analyzed, taking an inertial channel-type hydraulic mount as an example, the formulae of the amplitude-frequency characteristics of the mount stiffness is derived,and the methods of modal analysis and decoupling-degree calculation for the mounting system under the influence of nonlinearity is proposed. Then, a real case analysis on the vibration modes and decoupling-degrees of the hydraulic mounting system of powertrain with different amplitudes is carried out with this method. Finally, the criterion for modal type discrimination and the optimization objective of vertical decoupling-degree are summarized, and based on which an optimization on mount stiffness is conducted. The results show that the amplitude-frequency characteristics of hydraulic mount dynamic stiffness have a great influence on the vertical, torsional and rolling modes of the system, while the other modes are basically unaffected, and the optimized mount stiffness meet the requirements of vibration isolation. References | Related Articles | Metrics

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Test and Analysis of Rapid Acceleration Intake Noise in Automobiles Liu Zhien, Huang Tao, Shao Jiongyang, Zheng Qingqing, Du Songze, Li Qiuyue, Qu Shaoju, Liu Hao 2019, 41 (5):  564-570.  doi: 10.19562/j.chinasae.qcgc.2019.05.013 Abstract ( 265 )   PDF (4652KB) ( 395 )   Save The intake noise of a vehicle can directly affect the noise level and sound quality of the vehicle. In the process of the research of interior dynamic sound quality, it is necessary to enhance the dynamic sense of interior sound by the energy of intake noise. The traditional method of simply testing intake noise in the engine semi-anechoic chamber cannot meet the need of automobile sound quality research. Therefore, this paper proposes a method to obtain air intake noise and interior noise simultaneously on the NVH chassis dynamometer of the vehicle half-anechoic chamber. Through the subjective feeling of the field tester and the analysis of the test data, the effectiveness of the method is verified, and relatively pure intake noise can be obtained. The correlation between intake noise and vehicle interior sound quality under the condition of rapid acceleration is analyzed. Through the comparison of four typical objective parameters of sound quality, it is found that the intake noise is an excellent noise source in the realization of dynamic sound quality, which is of great significance to automobile sound quality design. References | Related Articles | Metrics

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Research Progress on Low-temperature Characteristics and HeatingTechniques of Vehicle Lithium-ion Battery Zhu Jiangong, Sun Zechang, Wei Xuezhe, Dai Haifeng, Fang Qiaohua, Tang Xuan 2019, 41 (5):  571-581.  doi: 10.19562/j.chinasae.qcgc.2019.05.014 Abstract ( 764 )   PDF (2530KB) ( 1920 )   Save In view of the deterioration of power characteristics and the lowering of charging and discharging efficiencies in traction battery, hampering the further development of electric vehicles , the tests of charging , discharging and electrochemical impedance spectroscopy characteristics are carried out on traction batteries with different material systems and specifications to analyze the key factors affecting the low-temperature performances of Li-ion traction batteries on one hand, and a comprehensive preview is conducted on the current research progress in low-temperature heating technology from the angle of traction battery thermal management on the other hand, aiming at providing a guidance for improving the low-temperature performance and the further research on low-temperature thermal management technique of traction batteries. References | Related Articles | Metrics

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An Experimental Study on Overcharge Behaviors of Lithium-ionPower Battery with LiNi0.6Co0.2Mn0.2O2 Cathode Zhu Xiaoqing, Wang Zhenpo, Wang Cong, Yi Mi 2019, 41 (5):  582-589.  doi: 10.19562/j.chinasae.qcgc.2019.05.015 Abstract ( 505 )   PDF (4157KB) ( 636 )   Save In this paper, the overcharge behaviors of 30 A·h pouch lithium-ion battery with LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode for electric vehicles are studied under different overcharge current rates (C-rates). The results indicate that the overcharge process can be divided into four stages. The highest surface temperature position of the cell is not fixed. In most test time, the maximum temperature difference (MTD) is less than 1 °C. It's worth noting that the C-rate has a great influence on the overcharge behaviors of Li-ion batteries. As C-rate increases, so do the maximum temperature and crest voltage, while the overcharge time and state of charge (SOC) value at the end of the test decrease as the C-rate increases. The study can provide a reference for the safety design of nickel-rich lithium-ion batteries and the safety management of the battery management system (BMS) for overcharge fault. References | Related Articles | Metrics

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Simulation Study on State of Charge Estimation ofLithium-ion Battery at Different Temperatures Jin Liqiang, Sun Zhixiang, Liu Zhiru, Li Jianhua, Yang Ming 2019, 41 (5):  590-598.  doi: 10.19562/j.chinasae.qcgc.2019.05.016 Abstract ( 283 )   PDF (1128KB) ( 811 )   Save In order to improve the accuracy of SOC estimation during the use of traction lithium-ion battery for meeting the requirements of battery management system for battery monitoring, a SOC estimation method for traction lithium-ion batteries at different temperatures is proposed. Firstly, through comparative analysis on control algorithm models, the second-order equivalent circuit model is selected,and according to the results of multiple temperature point experiment, the parameters of battery are fitted and a temperature-based battery parameter model is built. Then according to the improved extended Kalman filtering algorithm, a SOC estimation model is established. Finally, a rapid control prototyping simulation is carried out with DST and FUDS cycles to verify the robustness of the algorithm at different temperatures. The results show that the SOC estimation algorithm formulated can not only suppress the interference of current noise, but also make the estimated SOC value speedily converge to the real one when its initial value has a large error, with its error kept within 0.04 in the whole process of estimation. References | Related Articles | Metrics

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Comparative Study on the Failure of Adhesively Bonded GFRP/AluminumAlloy and Aluminum Alloy/Aluminum Alloy Joints Qin Guofeng, Na Jingxin, Mu Wenlong, Tan Wei, Liu Haolei 2019, 41 (5):  599-606.  doi: 10.19562/j.chinasae.qcgc.2019.05.017 Abstract ( 375 )   PDF (2964KB) ( 473 )   Save To reveal the failure rules of adhesively bonded glass fiber reinforced polymer (GFRP)/aluminum alloy and aluminum alloy/aluminum alloy joints subjected to different types of loads and temperatures, adhesive joints under tensile, shear, and combined tensile and shear stress states are manufactured, and tested at -40℃(low temperature), 25℃(room temperature) and 80℃(high temperature) to analyze the effects of temperature and stress state on the failure strength, failure modes and failure criteria of joints with consideration of the glass transition temperature Tg of the adhesive. The results show that the effect of temperature on the failure strength of GFRP/aluminum alloy joint is related to its stress state, but its extent of influence is lower than that on aluminum alloy/aluminum alloy joint. The most failure mode of aluminum alloy/ aluminum alloy joint is cohesive failure in adhesive, while GFRP/aluminum alloy joint is more prone to fiber tear or delamination failure, and hence its goodness of fit of failure criteria drops, with lowering temperature and increasing proportion of tensile stress. Therefore, the proportion of tensile stress should be taken as low as possible in designing the adhesively bonded structure of GFRP for lowering the tendency of fiber tear or delamination, and whose effects have also to be taken into consideration in failure prediction. References | Related Articles | Metrics