Abstract:To address the challenges of remote monitoring for pure electric loaders,a remote monitoring platform is developed based on the Qt software architecture method.This platform analyzes the requirements of real-time perception of multi-source information,intelligent fault early warning,network health management,and efficient data management in remote monitoring of pure electric loaders.The platform integrates real-time synchronized transmission of video and audio to achieve multi-perspective reconstruction of the working site;parses controller area network(CAN)messages to dynamically display key parameters such as vehicle speed,fuel pressure,and battery level while triggering abnormal alarms;implements intelligent hierarchical fault early warning to monitor faults and operational risks of core components such as vehicle controllers,motors,and batteries and issue multiple alarms;conducts dynamic network health monitoring to real-time identify network anomalies and interact with the vehicle system;and features data automatic storage and cleanup functions.The practical application results show that the platform can effectively improve the security of remote operations.

Abstract:In response to the reliability requirements of aluminum alloy wheels for a certain family car,a three-dimensional model of the wheel hub is established using CATIA software.The wheel hub is meshed and simulated using ANSA software,and the natural frequencies and modes of the wheel hub are calculated using post-processing software META.The reliability of the wheel hub design is quantitatively evaluated through the modal separation margin(MSM)index.The calculation results show that the natural frequency of the wheel hub is 383.3 Hz,significantly higher than the excitation frequency of flat road surfaces,uneven road surfaces,and the highest vibration frequency of the engine.The MSM of the wheel hub is 56.5％,far exceeding the minimum safety threshold,effectively avoiding the risk of resonance with adjacent components.The designed wheel hub has high reliability under complex working conditions.

Abstract:To improve the ignition stability of internal combustion engines in lean-burn mode,the effects of different ignition methods are analyzed from two perspectives:ignition principles and the coverage range of discharge plasma.The potential of the ignition system in combustion rate control and detonation suppression is discussed,and the development direction of advanced ignition systems is summarized.The analysis results show that the ignition system plays a key role in the combustion control process of internal combustion engines.Advanced ignition technology can ensure the ignition stability of internal combustion engines in lean-burn mode.Increasing ignition energy and ignition coverage can enhance ignition stability,but both will lead to a sharp increase in total ignition energy,requiring higher power for the ignition system,increasing system complexity,and reducing engine economy.Currently,the majority of ignition methods generate plasma ignition of the mixture through gas discharge.By adjusting the characteristics of the discharge plasma,the ignition system can flexibly control the combustion heat release throughout the combustion process in the cylinder.

Abstract:To address the frequent tearing failure of the rubber body of the elastic coupling at the flywheel end during the bench test of a diesel engine,torsional vibration tests of the shafting system and temperature rise tests of the rubber body of the elastic coupling are carried out to analyze the failure of the elastic coupling.Based on the AVL Excite Designer software,a 1D equivalent simplified model of the bench shafting system is established,and torsional vibration simulation analysis is conducted.An optimization method is adopted by increasing the moment of inertia between the elastomer at the dynamometer end and the universal joint of the cardan shaft,and the effectiveness is verified through simulation analysis and bench tests.The results show that resonance occurs between the first-order torsional vibration frequency of the shafting system and the second-order excitation frequency of the engine,leading to excessive torsional angle vibration of the rubber body of the elastic coupling,which causes torsional fatigue tearing and overheating melting of the rubber body,and finally results in the failure of the rubber body.Because the moment of inertia of dynamometer is greater than that of engine,the relative torsion angle of the rubber body of the elastic coupling at the flywheel end is greater than that at the dynamometer end,so the dissipated power of the rubber body of the elastic coupling at the flywheel end is greater than that at the dynamometer end,which leads to the elastic coupling at the flywheel end being more prone to failure.By increasing the moment of inertia between the elastomer at the dynamometer end and the universal joint of the cardan shaft,the first-order torsional vibration resonance frequency of the shafting system can be shifted away from the common speed range of the engine.Meanwhile,the dissipated power of the rubber body of the elastic coupling at the flywheel end is reduced by 33％,which prolongs the service life of the coupling rubber body and effectively solves the problem of frequent tearing of the rubber body of the elastic coupling at the flywheel end.

Abstract:To prevent resonance between the natural frequency of an automobile exhaust pipe,the main order vibration frequency of the engine,and the natural frequency of the cab acoustic cavity,the finite element model of the exhaust pipe is established by using Abaqus software,modal simulation analysis is carried out,optimization schemes are proposed,and comparative verification is conducted through modal analysis tests.The results show that the first-order natural frequency of the exhaust pipe is 24.23 Hz,while the engine idle vibration frequency is 25.00 Hz.The two frequencies are close to each other,indicating a high resonance risk.By adopting the two optimization schemes of changing the hanger position and adding an elbow to the straight pipe section of the exhaust pipe and conducting simulation analysis,the 11th-order natural frequency of the scheme that only changes the hanger position is close to the natural frequency of the cab acoustic cavity,which also has resonance risk.It is found that the first-order natural frequency of the exhaust pipe with an elbow added to the straight pipe section reaches 19.40 Hz,which effectively avoids the engine idle vibration frequency and solves the resonance problem between the natural frequency of the exhaust pipe and the engine idle vibration frequency.A comparison between the exhaust pipe modal analysis test and the finite element simulation shows that their vibration modes are basically consistent,and the deviations of the first-order and second-order vibration frequencies are both less than 8％,which verifies the effectiveness of the simulation model.

Abstract:In order to solve the fatigue fracture fault in the rotor punchings of an electric drive unit(EDU)assembly,a finite element model of the punchings is established to simulate the fatigue fracture phenomenon of the rotor punchings.The influence of punching thickness,punching material anisotropy,adhesive material,electromagnetic force,uneven contact between magnetic steels and punchings,temperature and other factors on punching stress are analyzed.The S-N curve of the material is refined based on stress test results.The rotor punching structure is optimized,the thickness of the intermediate magnetic bridge and the fillet radius at the fracture point are increased,and simulation and durability testing are conducted to verify the optimization scheme.The results show that the punching stress decreases continuously with the increase of punching thickness,and significantly increases with the increase of uneven contact between the magnetic steels and punchings.The influence of material anisotropy,adhesive,and electromagnetic force on the stress of the polarizer are relatively small,while temperature has a greater impact on the punching stress.After correcting the S-N curve of the material,the fatigue life simulation results are highly consistent with the experimental results,verifying the accuracy of the model.The simulated fatigue life of the optimized solution is 2.18 million cycles,far exceeding the requirement of 30 000 cycles,and has been verified by durability tests.This method successfully solve the problem of punchings fracture and improved the accuracy of punching fatigue life prediction.

Abstract:To clarify the friction pair wear information contained in diesel engine lubricating oil,spectral analysis is performed on 170 groups of lubricating oil samples collected during the durability test of a high-strengthened diesel engine.The nonlinear fitting method is adopted to analyze the correlation between the mass fractions of Fe,Cu,and Al elements in the oil and the wear of key friction pairs.A Python programming software is used to construct a random forest prediction model based on Fe element,and the receiver operating characteristic(ROC)curve is combined to evaluate the accuracy of the model.The results show that the mass fractions of Fe,Cu,and Al elements,which are mainly correlated with the wear of key friction pairs,are significantly concentrated in specific intervals.The mass fractions of Fe-Al elements can be used to correlate the wear of piston-piston ring-cylinder liner friction pairs,while the mass fractions of Fe-Cu elements can be used to correlate the wear of crankshaft-crankshaft bearing friction pairs.The normal wear interval and wear alert interval are set according to the mass fractions of Fe,Cu,and Al elements,and the accuracy of the constructed Fe-element random forest prediction model reaches 88.24％.There is a strong nonlinear correlation among the three main metal elements of Fe,Cu,and Al,and the wear alert interval can be used as a supplementary basis for diagnosing abnormal wear of piston-piston ring-cylinder liner and crankshaft-crankshaft bearing friction pairs in high-strengthened diesel engines.

Abstract:In order to improve the low-speed performance of a marine diesel engine,a electronically controlled wastegate system of a turbocharger is developed.The hardware and software of the system are designed,and the bench test are conducted to compare and analyze the effect of three turbochargers(wastegate-less turbocharger,mechanically controlled wastegate turbocharger,and electronically controlled wastegate turbocharger)on the performance of the diesel engine.The bench test results show that the performance of the diesel engine equipped with electronically controlled wastegate turbocharger is better than those equipped with either a wastegate-less turbocharger or a mechanically controlled wastegate turbocharger.Compared to a wastegate-less turbocharger,the electronically controlled wastegate turbocharger improves the low-speed performance of the marine diesel engine.When the load rate is 25％and 50％,it reduces fuel consumption by 6 and 13 g/(kW·h)and lowers exhaust temperature by 50 and 45℃,respectively,while increasing boost pressure after the intercooler by 20 and 50 kPa.

Abstract:To clarify the characteristics and prospects of mainstream unmanned aerial vehicle(UAV)power technologies,this study outlines the development of UAV technology,in response to industry needs for improved endurance,efficiency,and reliability,a multidimensional evaluation framework is constructed to compare electric,fuel-powered,and hybrid systems.The results indicate that UAV power technologies are becoming increasingly diversified and scenario-driven.Electric systems,with high reliability and low noise,dominate small-and medium-scale UAVs;fuel-powered systems,due to their high energy density,remain indispensable for long-endurance and heavy-payload tasks;hybrid systems,integrating the strengths of both,show strong potential for breaking endurance limitations and advancing UAV power systems toward higher efficiency and intelligence.

Abstract:To investigate the effects of hydraulic oil physical property parameters on the oil film pressure,surface elastic deformation,viscous friction,and hydraulic oil leakage of the piston pair,an axial piston pair oil film pressure equation and thickness equation are established.The oil film is discretized using the staggered grid method,and the oil film pressure,thickness,and surface elastic deformation of the piston pair are solved using MATLAB and Abaqus software,respectively.Python programming is used for real-time data exchange between MATLAB and Abaqus,achieving fluid solid coupling calculation of the piston pair oil film.A simplified stiffness model and Roelands viscosity temperature viscosity pressure equation for piston pair oil are established,and the influence of piston pair oil stiffness and viscosity on the lubrication characteristics of piston pair oil film are analyzed.The results show that the oil film stiffness has a significant impact on the oil film pressure of the piston pair.The oil film stiffness increases from 29 420 N/mm to 46 667 N/mm,and the average peak pressure of the piston pair oil film in the oil discharge are increases from 208.24 MPa to 259.93 MPa.However,the effect of the oil film stiffness on the surface elastic deformation,axial viscous friction force,and leakage of the piston pair is relatively small.The viscosity of hydraulic oil has a significant impact on the oil film pressure,viscous friction force,and leakage rate of the piston pair,but has little effect on the elastic deformation of the piston pair surface.The viscosity of hydraulic oil increases from 0.009 4 Pa·s to 0.022 5 Pa·s,and the average peak pressure of the piston pair oil film in the oil discharge are increases by 28.4％.The axial peak viscous friction force in the oil suction are increases by 154.8％,and the peak leakage rate in the oil discharge are decreases by 66.8％.

Abstract:To address the high failure rate of sealing rings during the press-fitting process of a certain diesel engine cylinder liner,the significant influencing factors causing sealing ring damage are identified through Failure Mode and Effects Analysis(FMEA).The effects of influencing factors on the press-fitting force are analyzed through experiments and with the help of Minitab software.A process optimization plan is proposed and tested for production validation.The results show that the high-risk influencing factors leading to sealing ring damage are the sealing ring assembly temperature,assembly oiling position,press-fitting speed,cylinder liner groove fillet radius,cylinder bore chamfer,and press-fitting force.The optimized cylinder liner assembly process is as follows:the measuring points for the cylinder bore chamfer are four points evenly distributed around the chamfer circumference,lubricating oil is applied to both the sealing ring and the cylinder bore chamfer,the cylinder liner groove fillet radius is 0.25 mm,the cylinder liner press-fitting speed is 5 mm/s,and the sealing ring assembly temperature is 60 ℃.The optimized experimental results show that the average press-fitting force of the cylinder liner is 1.128 kN,which closely matches the predicted optimal value,thereby confirming the effectiveness of the optimization measures.The actual production results show that the optimized process significantly improve the assembly quality and production efficiency of the cylinder liner.

Abstract:To enhance the adaptability of the inner and outer bypass splitter ring of aero-engines under multi-condition operating scenarios,a pneumatic optimization design study is conducted on the inner splitter ring model of a scaled dual-bypass fan-compressor stage test piece based on the Isight optimization design platform.The Bezier curve parameterization method is adopted to perform pneumatic calculations on the splitter ring model under set multi-condition operating conditions.Sample points are generated via Latin hypercube sampling,followed by design of experiment(DoE)analysis to screen key variables.The adaptive simulated annealing algorithm is then used for automatic optimization of these key variables,yielding an optimized splitter ring model with the minimum comprehensive flow loss.The static pressure and airflow velocity distributions in the inner and outer bypass ducts of three splitter ring profiles are analyzed under design conditions.Simulation results indicate that three design variables controlling the upper wall thickness of the splitter ring play a dominant role in the optimization outcomes.The optimized curve exhibits a concave and flattened trend,with increased curvatures at the leading and trailing edges,a reduced angle of attack of the splitter ring,which effectively suppresses flow separation and reduces flow loss.Through Bezier curve parameterization and multi-condition optimization design,the pneumatic performance of the splitter ring can be significantly improved,along with its adaptability under multi-condition operating conditions.

Abstract:To improve the pressure and temperature distribution within the bipolar plate flow field of a proton exchange membrane fuel cell(PEMFC),thereby enhancing its thermal management performance,a bipolar plate structure based on the Tesla valve is designed.A three-dimensional multiphysics coupled model is constructed based on AVL FIRE™ M,and the variable control method is employed to compare the influence of key geometric parameters such as Tesla valve angle,unit spacing,and channel spacing on pressure drop,temperature difference,and maximum temperature as the flow channel structure varied.The results indicate that a smaller channel spacing(6.0-7.0 mm)facilitates enhanced mass transfer under the ribs,a shorter unit spacing(1.0 mm)introduces high-frequency flow disturbances,and a moderate Tesla valve angle(125°-130°)generates vortex structures that improve mass transfer within a controllable pressure drop range.These three factors work synergistically to firm an efficient self-disturbing flow field,which prioritizes reactant supply and actively strengthens local heat and mass transfer,thereby improving the power density and operational stability of the PEMFC.

Abstract:To meet the increasingly stringent requirements for NOx emissions and NH3 slip,based on the reaction mechanism of ammonia slip catalyst(ASC)combined with reactor tests,the conversion process and products of NH3 over ASC are analyzed.By introducing inhibition factors related to NO concentration in the reactions of NH3 oxidation to N2 and N2O to distribute the NH3 oxidation pathways,an ASC kinetic model is established and simulated,and verified by bench tests.The simulation results show that when the reaction temperature is lower than 350 ℃,the main products of NH3 oxidation are N2 and N2O;the volume fraction of generated N2O reaches the maximum at 250 ℃.When the reaction temperature exceeds 350 ℃,the selectivity of NH3 oxidation products increasing NOx emission.Reactor tests and bench tests indicate that the ASC kinetic model can predict the volume fraction of NOx and N2O downstream of ASC,and the prediction error is no less than±10％for NH3 oxidation conversion rate.The model can accurately reflect the experimental characteristics of ASC.

Abstract:In order to reduce the noise of the crankshaft pulley,the fluid simulation software STAR ccm+is used to establish a flow field simulation model,and the acoustic software LMS Virtual lab is used to simulate the aerodynamic noise of the pulley and analyze the structural and acoustic cavity modes of the pulley.The simulation analysis results show that when pulley rotates at high speed,the groove flow velocity between the pulley and the front cover of the gear chamber is uneven,and periodic pressure pulsation is generated on the groove surface,which is the main source of aerodynamic noise of the pulley.A relatively closed cavity is formed inside the groove,and the first-order modal frequency of the acoustic cavity is close to the excitation frequency of the noise source,which increases the noise.The optimized scheme with a 5 mm opening on the pulley is used to compare and verify the aerodynamic noise simulation and testing with the original scheme without a hole on the pulley.The results show that compared with the original scheme,the optimized scheme reduces the root mean square sound pressure level of the aerodynamic noise simulation by about 4 dB,and the root mean square sound pressure level of the acceleration condition test by about 2 dB.The simulation and testing data of the original and optimized schemes are basically consistent,and the simulation method could be effectively used in engineering practice.

Abstract:In order to ensure the performance of a certain range-extended electric pickup,the parameter design of the four-wheel drive power transmission system of the range-extended electric pickup is studied.Based on MATLAB software,a mathematical model of a dual-motor four-wheel drive architecture including front and rear drive motors,a two-speed transmission,a power battery,and a range extender is established.According to the basic parameters and driving performance requirements of the pickup,the optimal performance parameters of the front and rear drive motors are calculated using the sequential quadratic programming(SQP)algorithm.In order to improve vehicle economy,the gear ratio of the two-speed transmission of the front and rear drive motors,configuration of the power battery capacity,and the parameters of the range extender are designed.Based on the new European driving cycle(NEDC),the energy consumption of the pack under constant speed,acceleration,and other working conditions is simulated and analyzed,and the driving range of the vehicle is calculated to verify the rationality of the parameter design of the range-extended electric four-wheel drive power system.The results show that the designed front and rear drive motor performance parameters can make the total maximum power of the vehicle motor 220 kW,and the total maximum torque of the motor reaches 621 N·m,which fully meets the power performance index of the maximum vehicle speed of 165 km/h,the acceleration time from 0 to 100 km/h is 8 s,and the maximum climbing angle at a speed of 30 km/h is 50%.After using the optimized vehicle power system parameters,the driving range in the NEDC cycle working condition is 124.78 km which meets the design requirement that the driving range shall not be less than 120 km.

Abstract:To address the uneven contact pressure distribution on the skirt and pin bore profiles of an aluminum piston in a diesel engine,a topology optimization design method is employed to collaboratively optimize the oval parameters of the skirt's transverse cross-section and the pin bore contour.Numerical simulations are conducted after iterative optimization.The results show that when the skirt's transverse cross-section adopts a superimposed corrected ellipse,combined with a double tapered pin bore structure optimized by adjusting the length of inner and outer linear segments and diameter recess,the contact pressure of the piston skirt and the peak contact pressure of the pin hole both decrease by 6%,and the contact area increases.After bench testing verification,the optimized key mating parts such as the piston skirt and pin hole have good contact,and there are no abnormal wear phenomena such as peeling on the piston surface under cyclic loading.The piston meets the durability requirements of the engine.

Abstract:To solve the fracture failure of a diesel engine connecting rod during fatigue testing,the macroscopic and microscopic morphologies of the fracture surface are observed,and metallographic structure analysis,energy spectrum analysis,non-metallic inclusion chemical composition and content grade inspection are carried out on the connecting rod to determine the cause of the fracture.Improvement measures are proposed,and fatigue and overall durability tests are conducted on the improved connecting rod.The results shows that there is a loose defect in the center of the steel rod used as the raw material for the connecting rod.After cutting and high-temperature forging,iron oxide is produced at the top of the small head of the connecting rod,which becomes a fatigue source under alternating loads,leading to cracks in the connecting rod;the sulfide inclusion content in the connecting rod is too high,the length exceeds the limit,and it has directionality,which causes cracks to propagate outward and accelerates the fracture process of the connecting rod.After taking improvement measures such as reducing the overheating of steel bars during continuous casting,improving the ultrasonic testing level,and reducing the content of sulfur and sulfides,the connecting rod successfully passes the fatigue test and the overall durability test,and there are no more incidents of connecting rod fracture failure.

Abstract:In order to verify the performance of different oil pumps,improve economy and production efficiency,a comprehensive test bench is designed and developed based on the performance requirements of the oil pump,which includes an integrated bench assembly,drive system,oil system,cooling system,electrical control and display system,and meets various oil pump testing requirements.The flow and power characteristics of the oil pump are tested and verified.The experimental results show that the designed oil pump comprehensive test bench can meet the performance requirements of various oil pumps,with safe,reliable,and convenient system operation,reasonable control methods,and can effectively reduce labor intensity and production costs.

Abstract:To meet the design requirements of the front-end selective catalytic reduction(SCR)mixer in a two-stage SCR device,a SCR urea crystallization prediction model is built in Fluent based on a chemical kinetics model to predict the quality,location,and composition distribution of urea crystals.The accuracy of the model is verified through engine bench crystallization tests.A new front-end SCR mixer is designed based on the crystallization prediction model to evaluate its performance.The results show that the simulation accuracy of crystal quality under low,medium,and high temperature conditions is 76%,79%,and 78%,respectively.The simulated crystallization position matches well with the experimental crystallization position,and the crystallization position is affected by exhaust temperature and exhaust flow rate.The crystal composition at different temperatures is basically consistent with existing related studies.The performance indicators of the new mixer are superior to existing products,with an increase of about 68%in anticrystallization ability.Ammonia uniformity and velocity uniformity are positively correlated with back pressure,while ammonia uniformity is negatively correlated with anticrystallization ability.