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Welcome to Journal of Automotive Safety and Energy,
汽车安全与节能学报

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  • 2021, Vol. 12 No. 3 Published on:30 September 2021 Previous issue    Next issue
    Review, Progress and Prospects
    Development and trends of direct injection hydrogen internal combustion engine technology
    SUN Baigang, BAO Lingzhi, LUO Qinghe
    2021, 12(3):  265-278.  doi:10.3969/j.issn.1674-8484.2021.03.001
    Abstract ( 1111 )   HTML ( 68)   PDF (1487KB) ( 1620 )  

    Hydrogen energy is the best energy carrier to achieve carbon peak and carbon neutrality, and is also regarded as the ultimate energy source in the 21st century. The hydrogen internal combustion engine has the significant advantages of zero carbon emission, high efficiency, high reliability and low cost, which makes it one of the important directions for hydrogen energy applications. The direct-injection hydrogen internal combustion engine, which can effectively suppress backfire and significantly increase power density, is a hot topic in the recent stage of development of hydrogen engine. It has attracted much attention from traditional automobile companies and research institutes at home and abroad. This paper systematically summarizes the advantages and disadvantages of various types of hydrogen internal combustion engines as well as the technical approaches and the details of the relevant hydrogen engines. The utilize of exhaust gas turbocharging can make the power density of hydrogen internal combustion engine reach 80 kW/L. High compression ratio and lean burn combustion can reach the brake thermal efficiency to 42% ~ 45%, and the exhaust gas recirculation technology can reduce the NOx pollutant of hydrogen engine less than 0.5 g/kWh. The paper also addresses the new issues posed by the next-generation direct-injection hydrogen engine, analyzing the current state of development and the technical details including mixture formation, combustion characteristics, combustion mode, effective thermal efficiency improvement, NOx control methods and post-processors. We also discuss the future technological development trend of reaching 50% brake thermal efficiency under near-zero emission working conditions.

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    Review on the research of motion planning and control for intelligent vehicles
    CAI Guoshun, LIU Haoji, FENG Jiwei, XU Liwei, YIN Guodong
    2021, 12(3):  279-297.  doi:10.3969/j.issn.1674-8484.2021.03.002
    Abstract ( 849 )   HTML ( 28)   PDF (3061KB) ( 2739 )  

    This paper discussed the research status of motion planning and control theories and methods for intelligent vehicles with analyzing the path planning, trajectory planning, lateral and longitudinal control technique to promote the comprehensive driving performance. The present research of motion planning mostly based on the vehicle models and constraints simplifying with less consideration of the communication loss, network security, and mixed traffic scenarios. And the present research on control techniques focused on the design of lateral and longitudinal control strategy independently, and without considering the system non-linear characteristics, time delay and random uncertainty in depth. Hence, to realize the comprehensive multi-objective collaborative control with satisfying the lateral and longitudinal dynamics in complex dynamic scenarios, utilizing the multi-sensor information fusion and advanced communication technology is a significant research direction for safety and economy driving of intelligent vehicles.

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    Automotive Safety
    Vibration characteristics analysis on driving-axle main-reducer
    HUANG Zhichao, ZHAO Yiguang, HU Yihua, LIU Ming
    2021, 12(3):  298-304.  doi:10.3969/j.issn.1674-8484.2021.03.003
    Abstract ( 423 )   HTML ( 13)   PDF (2098KB) ( 391 )  

    The vibration characteristics were analyzed for the main-reducer of an automobile drive-axle housing by using simulations and tests. A finite element (FE) model was established with HyperMesh. Modal analysis was carried out within an OptiStruct module to solve the natural frequency and modal vibration mode of the main-reducer housing. Modal experiments and vibration and noise tests were carried out. The FE analysis results were compared with the experimental results. The results show that the main-reducer shell natural frequency is greater than 1.2 kHz with a large stiffness. The modal shapes happen mainly at the rear end of main-reducer housing. The accuracy of the main reducer housing FE model is verified. The vibration and noise level exceed the standard value at 1 800~2 000 r/min. By analyzing its frequency and frequency doubling, it is speculated that it is caused by the vibration of the main-reducer gear-teeth. These results may be references for NVH (subsequent noise, vibration and harshness) performance optimization of drive-axle.

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    Advanced ORB algorithm of image feature uniform distribution based on threshold adaptive
    SHI Peicheng, YANG Jianfeng, LIANG Taonian, QI Heng
    2021, 12(3):  305-313.  doi:10.3969/j.issn.1674-8484.2021.03.004
    Abstract ( 450 )   HTML ( 8)   PDF (2100KB) ( 221 )  

    Camera-based visual SLAM (simultaneous localization and mapping) for driverless vehicles could be used to complete the localization and mapping of driverless vehicles. In order to solve the problems that the traditional ORB (Oriented FAST and Rotated BRIEF) algorithm could easily cause clutter and concentration of distribution when extracting image feature points, an advanced ORB (A-ORB) algorithm was proposed which limited the splitting depth of quadtree algorithm. This algorithm constructed an image pyramid to solve the scale invariance problem. According to the total number of feature points extracted, the algorithm calculated the feature points that needed to be extracted for each layer of the pyramid. The image of each pyramid layer was divided into adaptive regions and the threshold of feature point extraction was calculated according to the image information. This algorithm used improved quadtree algorithm to homogenize the distribution feature points. The simulation experiment was carried out. The results show that compared with ORB, MA and S-ORB algorithms, the running efficiency of the advanced ORB is increased by more than 30%, and the matching accuracy is increased by more than 10%.

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    Simulation analysis for the effect of notchback-car rear structure on wake-field aerodynamic characteristics
    QU Xian, YU Feng, ZHANG Jinlong
    2021, 12(3):  314-321.  doi:10.3969/j.issn.1674-8484.2021.03.005
    Abstract ( 151 )   HTML ( 4)   PDF (2106KB) ( 148 )  

    The influence of notchback-car rear parts on aerodynamic characteristics was investigated to improve the aerodynamic shape and to reduce its aerodynamic resistance. The wake field of the MIRA model was simulated by using software Star-ccm+ to analyze the key rear structures affecting its flow field. The subjects were determined as six tail structures, including the roof angles, the rear window, the side window, the tail-up, the tail end face, and the trunk length, to investigate its influencing aerodynamic characteristics. An orthogonal optimization test of the rear structures was designed from the view of the whole rear structures. Optimized analysis of rear aerodynamic structures was developed with consideration of the interaction between each structure. The results show that the tail-up angle, the rear window angle, and the roof angle play key roles in designing the vehicle’s rear aerodynamic shape. The drag coefficient is reduced to 14.4% after the orthogonal optimization of the rear structures. Therefore, the optimal structure improves the vehicle rear flow.

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    Occupant protection analysis based on the China National Standard GB 11552 about sled test method
    WU Yongqiang, LOU Lei, FENG Qi
    2021, 12(3):  322-327.  doi:10.3969/j.issn.1674-8484.2021.03.006
    Abstract ( 677 )   HTML ( 14)   PDF (915KB) ( 1177 )  

    Six kinds of collision conditions were built including the 5th dummy +18°, the 50th dummy +18°, the 95th dummy +18°, the 5th dummy -18°, the 50th dummy -18° and the 95th dummy -18°, based on a sled collision test platform, to improve the National Standard GB 11552 of China for protecting passengers’ safety. The dummy injuries were analyzed in 130 tests of 40 models, to explore the injury risk of torso and lower limbs of occupants. The results show that the dummy head injury factors are 0.66, 0.69, 0.73, 0.95, 0.90 and 0.72 in the six test conditions respectively, having a risk factor of approaching 1 for the dummy torso injury, and having some injury risk for dummy lower limbs. A greater size dummy has a greater injury risk at lower limb, with the injury risk near the impact side of lower limb is higher than that on the other side. Therefore, the authors suggest that the torso and lower limbs of a dummy should be defined appropriately in a future China National Standard GB 11552.

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    Design and simulation of magnetorheological suspension based on spherical motor
    YANG Yang, DENG Tao, CAO Li, LI Qiang
    2021, 12(3):  328-335.  doi:10.3969/j.issn.1674-8484.2021.03.007
    Abstract ( 194 )   HTML ( 3)   PDF (1571KB) ( 334 )  

    A new type of magnetorheological suspension was designed based on a multi-degree-of-freedom spherical-motor to apply this kind of motor in automobile. The main structure was designed of the magnetorheological suspension with analyzing the static strength of the suspension and magnetic field simulation of the damper using ANSYS software. Obtained a stress nephograph of the suspension and the magnetic induction intensity nephograph of the damper; Established a two-degree-of-freedom dynamic model to simulate ride comfort. The results show that the suspension maximum stress under three working conditions, including the maximum braking force, the maximum vertical force, and the maximum lateral force, does not exceed the material allowable stress of 355 MPa. The vehicle body acceleration is 0.23 m/s2; The tire maximum dynamic load is 2 kN; The suspension maximum dynamic deflection is less than 50 mm. Therefore, the structural design meets both the static strength requirements and the expected suspension ride comfort.

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    Research on dangerous scene of T-intersection based on NAIS database accident data clustering
    LIAO Jingqian, ZHANG Daowen, GAO Li, LIAO Wenjun
    2021, 12(3):  336-345.  doi:10.3969/j.issn.1674-8484.2021.03.008
    Abstract ( 552 )   HTML ( 12)   PDF (1894KB) ( 305 )  

    Based on the National Automobile Accident in-Depth Investigation System (NAIS) database, the T-intersection dangerous scenarios in the traffic environment was investigated. 4 types of T-intersection dangerous accident scenarios were obtained with MATLAB software for cluster analysis and by using the hierarchical clustering method. Through the kinematic analysis and modeling of the 3 types of dangerous scenes when turning, the speed-distance dangerous model was constructed, and the kinematic parameters were combined to obtain the dangerous collision domains under the 3 types of T-junction turning dangerous scenes. The results show that under the conditions of conflict between a passenger vehicle going straight and a passenger vehicle turning left, the dangerous collision range is 1.67~68.45 m when the passenger car turns left at entrance 1; while the dangerous collision range is -1.20~136.00 m when the passenger car turns left at entrance 3; when a commercial vehicle turns right and a two-wheeler goes straight, the dangerous collision range is 0.78~121.30 m; the dangerous collision range is -15.75~283.30 m when a commercial vehicle turns right and a commercial vehicle goes straight. The results of the research can be used as a reference for the development and testing of auxiliary driving safety systems.

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    Model reference adaptive stability control for independent driving electric vehicle
    LI Jialin, AO Di, WANG Yang, XIONG Rui
    2021, 12(3):  355-363.  doi:10.3969/j.issn.1674-8484.2021.03.010
    Abstract ( 449 )   HTML ( 12)   PDF (1519KB) ( 197 )  

    A direct yaw moment controller algorithm was designed based on a model reference adaptive control (MRAC) to improve the lateral stability and safety for four-wheel independent electric vehicles (EV). The upper-level controller was based on the Lyapunov function to estimate the tire corning stiffness and vehicle mass in real-time and obtain the additional yaw moment. The lower-level controller allocated the requested yaw moment to each wheel via an optimized quadratic programming algorithm, and guarantees the real-time dynamic response of the controller. The results from Carsim and Simulink co-simulation under double lane change driving mode show that the proposed MRAC controller algorithm outperforms the conventional sliding mode controller (SMC) with the reductions for mean absolute errors of yaw rate and sideslip angle by 43.0% and 37.1% under 0.85 adhesion ratio; with 25.3% and 23.2% reductions under 0.40 adhesion ratio. Therefore, the proposed MRAC controller algorithm improves the vehicle lateral stability and safety.

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    Crash characteristics of rear protective device of tank truck carrying dangerous goods based on finite element simulation
    SHEN Xiaoyan, YU Zhengtao, QIN Xiao, CHEN Ye, ZHANG Guosheng, LI Jin
    2021, 12(3):  364-372.  doi:10.3969/j.issn.1674-8484.2021.03.011
    Abstract ( 212 )   HTML ( 2)   PDF (2368KB) ( 158 )  

    The idea of installing rear guards at the tail of the tank was proposed to effectively reduce the severity of rear-end collisions between tank truck of liquid dangerous goods and large passenger car. Through the comparative analysis of real rear-end collision test and numerical simulation, the effectiveness of the simulation model was verified. Then, it was further analyzed that dynamic response characteristics of the tank truck and the protective performance of the protective device under different masses of collision vehicle, collision speeds, collision angles and center of mass heights. The results show that the numerical simulation model is feasible; and the designed rear protective device can adapt to different collision conditions and has good protective performance, with excellent protective effect under the relative impact velocity below 50 km/h, and can normally block the impact of passenger cars below 25 t; meanwhile, also can effectively protect the tank in an area of 120°; the maximum acceleration peak value does not exceed 10g at different heights of the center of mass.

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    Automotive Energy Efficiency and Environment Protection
    Eco-driving strategy at ramp road for hybrid electric vehicles based on two-state dynamic programming
    FU Xueqing, WANG Baosen, YANG Jianjun, GAO Haiyang, HE Bangquan, ZHAO Hua, GUO Wencui, LIU Shuangxi
    2021, 12(3):  373-379.  doi:10.3969/j.issn.1674-8484.2021.03.012
    Abstract ( 309 )   HTML ( 7)   PDF (793KB) ( 150 )  

    The effect of driving time of on-road vehicles on eco-driving (ECO) strategy at ramp road was investigated for hybrid electric vehicles (HEV) by using adjusting vehicle speeds to reduce the energy consumed by vehicles. An ECO strategy model was established based on two-state dynamic programming with driving distance and vehicle speed selected as two states, and driving time as a stage variable; The sum of driving and braking energy was used as objection function due to the fuel economy of on-road HEV mainly affected by vehicle energy demand. After calculation from the vehicle model of a HEV operating at different driving strategies, the results show that the fuel economy of the HEV at ECO strategy reduces by 17.6 % for up-down road and 12.2 % for down-up road respectively compared to fixed-speed driving strategy; The influence of driving time on the fuel economy of the HEV at ECO strategy is more obvious at up-down road than at down-up road.

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    Cooling performance simulation of the power battery pack based on straight liquid cooling plate
    CAI Senlin, WEI Mingshan, SONG Panpan, WEI Hongge
    2021, 12(3):  380-385.  doi:10.3969/j.issn.1674-8484.2021.03.013
    Abstract ( 164 )   HTML ( 3)   PDF (1473KB) ( 354 )  

    A liquid cooling plate structure with a parallel non-equal-length channel was proposed to improve the heat dissipation ability of the power battery pack of a commercial vehicle and to reduce the energy consumption of the cooling system of the battery pack. A simulation model of a liquid cooling prismatic lithium-ion battery pack was established to optimize the structure of liquid cooling plate. The results show that the cooling plate not only meets the cooling capacity of the battery pack, but also can effectively control the pressure drop. The pressure drop of the liquid cooling plate decreases by 12.5 kPa, and the maximum temperature and maximum temperature difference in the battery pack decrease by 0.26 ℃ and 0.27 ℃, respectively. Adjustments on the flow rate and temperature of coolants could enhance the heat dissipation capacity of the battery pack to keep the battery pack working within a reasonable temperature range.

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    Sliding mode MRAS control for permanent magnet synchronous motor based on an improved GWO algorithm
    WANG Zelin, HU Qiguo
    2021, 12(3):  386-394.  doi:10.3969/j.issn.1674-8484.2021.03.014
    Abstract ( 212 )   HTML ( 2)   PDF (2109KB) ( 196 )  

    An improved sliding mode model reference adaptive system (MRAS) was designed to improve the control performance of traditional permanent magnet synchronous motor (PMSM) sliding mode MRAS. Based on the integral sliding mode surface of traditional sliding mode MRAS, the non-singular fast terminal sliding mode surface was introduced, which constitutes an integral non-singular fast terminal sliding mode surface to improve the convergence performance. A nonlinear exponential function was used to replace the switching function in the traditional sliding mode MRAS, and an improved gray wolf optimization (GWO) algorithm was used to optimize the sliding mode surface parameters globally to improve the control precision. The simulation results of MATLAB/Simulink software show that compare with the traditional sliding mode MRAS, the improved sliding mode MRAS can reduce the torque ripple amplitude by 75%, reduce the actual speed jitter amplitude by 80%, control the actual speed overshot within 2.3%, control the adjustment time within 10 ms, and reduce the observation error of rotor position by 60%.

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    Acrylamide and ether-based polymer gel electrolytes for high performance solid zinc-air batteries
    ZHANG Pengfei, WANG Keliang, PEI Pucheng, ZUO Yayu, WEI Manhui, LIU Xiaotian, XIAO Yu
    2021, 12(3):  395-401.  doi:10.3969/j.issn.1674-8484.2021.03.015
    Abstract ( 534 )   HTML ( 16)   PDF (2261KB) ( 385 )  

    Introducing additives into the electrolyte was investigated to improve the disadvantages of electrolyte leakage and corrosion of metal shell of traditional button zinc-air battery and to optimize the performance of zinc-air battery meanwhile. The gel electrolyte prepared by mixing acrylamide and ether polymers was compared with the electrolyte prepared by pure acrylamide. The charge and discharge performance of button zinc-air batteries composed of two kinds of gel electrolytes were tested respectively, and the results of the two groups of tests were compared and analyzed. The results show that compared with the traditional polyacrylamide (PAM) electrolyte, the viscosity and ionic conductivity of the new electrolyte with ether polymer are significantly improved. The assembled button zinc-air battery shows so better cycle stability that it can be charged and discharged at 5 mA current for more than 35 h, which indicates that the addition of ether polymer to acrylamide can improve the performance of electrolyte and zinc-air battery.

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    Analysis of lean combustion and emission characteristics of Miller cycle gasoline engine
    YIN Aiyong, HUANG Zhaoming, WANG Li, SHEN Kai, CHEN Weiguo
    2021, 12(3):  402-409.  doi:10.3969/j.issn.1674-8484.2021.03.016
    Abstract ( 200 )   HTML ( 2)   PDF (1599KB) ( 304 )  

    The influence factors of lean burn process on combustion and emission of supercharged Miller cycle direct injection gasoline engine was experimentally investigated, in which the influence law of lean burn combined with exhaust gas recirculation (EGR) on fuel consumption rate of gasoline engine was analyzed, and the cylinder lean burn process was visually analyzed with a transparent engine. The results show that the fuel consumption rate decreases by about 7% when the excess air coefficient (λ) is 1.55 and the fuel consumption rate increases inversely with increasing λ; Lean burn leads to strong Miller effect and the expansion ability of air-fuel ratio is limited, resulting to the improvement of fuel consumption rate is reduced; At the initial stage of λ rising, the combustion delay period extending by crank angle (CA) 1° is corresponding to the combustion duration of 10% - 90% extending CA 1°. Increasing EGR rate and improving λ can effectively reduce the fuel consumption rate, and the EGR rate in equivalent combustion mode is 14%, which is equivalent to the contribution to fuel consumption rate in lean combustion mode when λ is 1.35. When λ reaches 1.27, the fuel consumption rate in lean burn mode can be reduced by 7.5% than that in equivalent combustion mode under the condition of 14% EGR rate.

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    Optical diagnostics of charge stratification compression ignition in high compression ratio gasoline engine
    ZHANG Zhiyong, GAO Dingwei, LAI Haipeng, ZHANG Bin, XING Huafeng
    2021, 12(3):  410-416.  doi:10.3969/j.issn.1674-8484.2021.03.017
    Abstract ( 189 )   HTML ( 2)   PDF (1494KB) ( 226 )  

    An optical diagnostic on charge stratification compression ignition was used to investigate the influences of gasoline direct injection (GDI) duration, timing and rail pressure to charge stratification compression ignition. Based on a single-cylinder optical engine with port injection method to inform pre-mixture and direct injection fuel to induce ignition, some experiments were developed under the conditions at different GDI duration of 0.5, 1.2, and 2 ms, with different timing at crank angles (before top dead center) of 40°, 50°, 60°, 80°, and 100°, and with different rail pressure of 3.8, 10, 15 MPa. The results show that charge stratification compression ignition is realized by adopting high compression ratio, normal valve timing, port injection to inform pre-mixture and direct injection fuel to induce ignition. Success chance of compression combustion is increased, combustion stability is improved, and the emission of soot is reduced by reasonable calibration to GDI duration, timing and rail pressure.

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