Friction and Wear Performance of Double-bump Design of Piston Skirt Main Thrust Side

Bifeng Yin,Jiajun Zu,Bo Xu,Gongyin Huang,Manying Yang 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.6

As a key component of the engine, piston have to work in harsh environment for a very long time, its friction performance and operational reliability have been the research focus. In this paper, a four-cylinder diesel engine was used as the research object. The dynamic model considering multi-factors such as inertial parameters, surface roughness, thermal deformation and elastic deformation was established in Ricardo-Pisdyn software. The research mainly focused on the doublebump design of the main thrust side of the piston (exploring the parameters of the upper bump height, cavity depth etc.) on the friction and wear performance. The research showed that appropriately increasing the depth of the cavity can improve the wear within a certain range. However, if the cavity depth increase too much, the abrasion of the main thrust surface will be aggravated. After optimizing of the clearance and adopting the double-bump profile on the main thrust side, the accumulated wear load of the piston can be significantly reduced and its friction and wear performance will be improved. In this paper, the optimized accumulated wear load decreases from 31.65 MW/m2 to 14.64 MW/m2, drops by 53.7 %.

Study on Tribological Properties of Laser-Textured Plunger in Methanol Engine

Bifeng Yin,Yuhao Jiang,Bo Xu,Hekun Jia,Xuefeng Wang 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.4

Considering the eccentricity and deformation of the plunger, a lubrication model of laser-textured plunger pair was established to research friction-and-wear performance of typical surface texture on the plunger under diesel and methanol lubrication. The calculation results show that for the non-textured plunger, the oil film thickness and fluid friction under methanol lubrication are lower than diesel lubrication, and the asperity friction was greater than diesel lubrication, indicating that methanol may deteriorate the lubrication performance of the plunger surface. After texturing the plunger, the oil film thickness and fluid friction during methanol lubrication are greater than the non-textured scheme, and the asperity friction is lower than the non-textured scheme, which means that the surface texture has the potential to improve the lubrication performance of the plunger. The friction and wear tests results indicate that the average friction coefficient of the textured plunger is reduced by 3.4 ~ 6.2 % compared with the non-textured plunger in methanol lubrication. The lubrication performance of the textured plunger during methanol lubrication reaches the level of the non-textured plunger in diesel lubrication. After the wear test, the surface wear depth of the textured plunger is reduced by 16.2 % compared with the non-textured plunger in methanol lubrication condition.

Performance optimization of diesel engine fueled with diesel–jatropha curcas biodiesel blend using response surface methodology

Huaping Xu,Bifeng Yin,Shengji Liu,Hekun Jia 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8

The present work is aimed at unfolding the effect of fuel supply parameters such as Fuel injection pressure (FIP), Start of injection timing (SOI), Pilot-main injection intervals (PMII) on performance and emission characteristics of 20 % blend of Jatropha curcas biodiesel (J20) under light load operation of a diesel engine. The experiments were designed using design of experiments based on the fractional factorial design of Response surface methodology (RSM). Multiple regression models developed using RSM for measured responses like nitrogen oxides (NO X ), SOOT, hydrocarbon (HC), Brake specific fuel consumption (BSFC) and Brake thermal efficiency (BTE), were found to be statistically significant by Analysis of variance (ANOVA). Interactive effects among FIP, SOI and PMII were analyzed using response surface graphs that were fitted using developed RSM models. Optimization was performed using the desirability approach of the RSM for lesser emissions and BSFC simultaneously with superior BTE. A FIP of 134.11 MPa, SOI of 6.4 BTDC, and PMII of 5.8 CA were found to be optimal values for J20 in the test engine of 21 kW at 1800 rpm. The results of this study show that at optimal input parameters, the values of the NO X , SOOT, HC, BSFC and BTE with a high desirability of 96.7 % are 603.44 ppm, 0.037 FSN, 12.73 ppm, 233.26 g/kW h and 37.31 %, respectively.

Tribological performance of surface treated piston assembly with infiltrated layer

Bo Xu,Bifeng Yin,Dashu Gao,Xijun Hua 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1

By applying surface treatment on piston assembly and typical samples, an infiltrated layer with the depth of about 30 μm was formed on the treated sample surface. The surface hardness and linear expansion coefficient of treated piston sample decreased, while the hardness of treated ring sample increased. The results of ball-on-disc rotating friction test indicated that the infiltrated layer is helpful for improving the tribological properties of aluminum alloy, reducing friction coefficient under both dry friction and oil lubricated conditions, and improving the anti-friction and wear resistance performance of cast iron. In addition, the reciprocating friction testing results showed that surface treatment technology has stable antifriction effect on piston/liner pair under various working conditions, with the average friction coefficient being reduced by about 10.2-22.1 %; while the anti-friction effect on ring/liner pair is mainly reflected under low-speed heavy-load condition, with the average friction coefficient being reduced by approximately 7.2-9.9 %.

Visualization of combustion performance and emission characteristics of a four-cylinder diesel engine at various inlet oxygen concentrations at part loads

Huaping Xu,Shengji Liu,Bifeng Yin,Hekun Jia,Shenghao Yu 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6

Although exhaust gas recirculation (EGR) is a common way to suppress the nitrogen oxide (NO X ) emissions, it also brings some negative impact on soot emissions and the thermal efficiency in internal combustion engines. We investigated the effects of ambient oxygen concentrations on engine performance, combustion characteristics, and emissions using a four-cylinder diesel engine equipped with an endoscopic visualization system. To estimate the flame temperature and soot distribution, we analyzed these images using a postprocessing program. Experimental results showed that the luminosity of flames in the images was degraded comparatively for the reduced oxygen concentration. Flame temperature distribution also showed similar behavior. As the oxygen concentration decreased, area of soot distribution significantly reduced at IMEP = 0.13 MPa, and only a slight decrease at IMEP = 0.3 MPa. But locally high soot concentration regions increased.

ADAPTIVE ENERGY MANAGEMENT STRATEGY OF FUEL CELL ELECTRIC VEHICLE

Yan Sun,Changgao Xia,Bifeng Yin,Yingxiao Yu,Jiangyi Han,Haiyu Gao 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.5

The energy management strategy (EMS) can efficiently split the power among different sources for a fuel cell electric vehicle (FCEV). This paper puts forward how to cooperate with a proton exchange membrane fuel cell as the primary energy source, and a ultracapacitor as the auxiliary energy storage. Firstly, the test bench of fuel cell is built and the characteristic of fuel cell is tested. A model of vehicle is built in AMESim software based on the real parameters of vehicle especially the characteristic of fuel cell. Secondly, the traditional power following strategy is introduced and an optimal energy management strategy is proposed. The demand power is decomposed by quadratic utility function (QUF) and Karush-Kuhn-Tucker (KKT) condition. In order to balance the vehicle economy and durability of fuel cell, the multi-objective artificial bee colony algorithm (MOABC) and pareto solution set are used to solve the optimal balance coefficient in the algorithm. The simulation results show that compared with the traditional strategy under one WLTP driving cycle, the novel strategy can reduce the fuel cell degradation by 25.08 %, and the equivalent hydrogen consumption can be also reduced.

VISUALIZATION RESEARCH AND OPTIMIZATION STRATEGY FOR COMBUSTION PROCESS AND EMISSION CHARACTERISTICS OF INTERNAL EXHAUST GAS RECIRCULATION SMALL NON-ROAD DIESEL ENGINE

Jia Hekun,Liu Zhiyuan,Yin Bifeng,Zhang Xin,Xu Yi 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.2

Based on a small non-road diesel engine, internal exhaust gas recirculation (IEGR) was realized by the exhaust valve re-opening (2EVO). The influences of IEGR on combustion and emission performance were analyzed. The results showed that in-cylinder pressure peak decreased, the start of heat release was delayed by 0.5 °CA and the heat release rate peak was reduced after the introduction of IEGR. Furthermore, the average temperature of combustion flame was reduced, centering between 1900 and 2100 K. That was beneficial to curbed nitrogen oxides (NOX) emissions. The average value for KL factor was obviously increased within the entire range of combustion, which resulting in an increase in soot emission. In terms of emission characteristics, NOX emission was significantly reduced under the original injection timing but soot emission was increased slightly. Subsequently, the start of injection (SOI) were adjusted based on IEGR and two fuel injection control strategies were formulated from the perspective of reducing pollutant emissions and fuel consumption: Strategy 1 keeping BSFC consistent with the original engine, the NOX+HC weighted emission was reduced by 17.6 %; Strategy 2 keeping NOX+HC emissions consistent with the original engine, BSFC and CO were reduced by 10 % and 20 % respectively and Soot emission was slightly increased.

ADAPTABILITY OF LASER TEXTURED LINER TO THE EFFECTS OF METHANOL DILUTING OIL ON TRIBOLOGICAL PROPERTIES

Jia He Kun,Xu Bo,Yin Bifeng,Jiang Yuhao,Hu Nanrong 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.2

With the increase of methanol diluting lubrication oil, the dynamic viscosity of the mixture presents a downward trend, the total acid number grows while the total base number declines, and the corrosion degree of copper strip upgrades, which indicates that methanol dilution has negative effects on lubrication and anti-corrosion performance of oil. According to ball-on-plate friction test results, the friction coefficient and surface wear of this pair increase in turn with the rising methanol dilution rate, which tends to deteriorate the tribological performance of key friction pairs in methanol engine. After laser surface texturing cylinder liner, the friction coefficient of ring/liner pair is reduced, and the anti-friction effect is enhanced with the rising methanol dilution rate, because the oil storage capacity of textured micro-dimples on liner surface can improve the lubrication of ring/liner pair and reduce asperity contact. Moreover, the micro-dimples can store debris generated in the reciprocating friction process of this pair, so as to alleviate surface wear caused by abrasive wear, and improve the wear resistance of cylinder liner. Therefore, laser texturing cylinder liner can compensate the deterioration of friction and wear performance of ring/liner pair caused by methanol diluting oil with good lubrication adaptability.

Improvement of Energy Saving for Hybrid Hydraulic Excavator with Novel Powertrain

Yingxiao Yu,Tri Cuong Do,Bifeng Yin,Kyoung Kwan Ahn 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.2

To reduce the energy consumption and emission, an innovative powertrain and the energy management strategy are proposed for hydraulic excavator in this paper. The novel powertrain consists of the engine, motor/generator, planetary gear, gearbox, and variable hydraulic pump. The energy regeneration system is also applied on the system to regenerate the potential energy and charge the battery. An improved equivalent consumption minimization strategy is proposed to control the engine, motor/generator, hydraulic pump and gearbox. The engine working points can be located in high efficiency range, with the proposed powertrain and the energy management strategy. To verify the energy saving efficiency of the proposed system, the test bench is built in laboratory. Compared with the current hybrid system, the energy saving efficiency reaches 11% in condition of a large velocity. Compared with the current hybrid system and conventional system, the energy saving efficiencies are 4% and 48% respectively with different cylinder velocities. The fuel consumption and emission of hydraulic excavator can be reduced effectively with the proposed powertrain and energy management strategy.

GPIO BASED SLIDING MODE CONTROL FOR DIESEL ENGINE HIGH PRESSURE COMMON RAIL SYSTEM

Zheng Yuan,Chen Dai,Hao Sun,Shihua Li,Bifeng Yin 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.1

With the rapid development of diesel engines, reducing the pressure fluctuation of the common rail has become a key factor to improve the performance of the high pressure common rail (HPCR) system. Among traditional rail pressure control approaches, the influence of time-varying disturbances on the HPCR system is not fully considered and is not well dealt with. To this end, a nonlinear model of the HPCR system is firstly established based on fluid dynamics and mechanics laws. And a composite controller based on the nonlinear model is proposed. It consists of two parts: 1) A sliding mode feedback part; 2) A disturbance feedforward compensation part based on a generalized proportional integral observer. Finally, a group of test is simulated in the AMESim simulation environment and the results are shown to demonstrate the effectiveness of the proposed method.