Abstract:In order to accurately evaluate the safety performance of a passenger car during a frontal collision,a geometric model of the vehicle is established using CATIA software,and the model is preprocessed using ANSA simulation software.LS-DYNA solver is used to for calculation,and HyperView is used for post-processing and data analysis.The deformation of the front crash beam,energy absorbing box,front longitudinal beam assembly,front wall panel and battery pack during the frontal collision test of the vehicle is simulated and analyzed.The results show that the maximum acceleration of the B-pillars on the left and right sides is 67.325g(g is the free fall acceleration)and 62.213g,respectively,both of them meet the standard requirement that the maximum acceleration on both sides should not exceed 72g.The maximum energy absorption point of the energy absorbing box is located at the front end,with a maximum displacement of 465.281 mm,effectively absorbing collision energy.The front longitudinal beam assembly absorbs energy of 21 kJ,accounting for approximately 27％of the total collision energy,and has a good energy absorption effect.The maximum deformation of the front panel is 24.80 mm,which does not invade the passenger compartment and ensures the safety of the driver and passengers.The maximum deformation of the battery pack bracket is 0.17 mm,which is less than the material deformation threshold(0.20 mm)and meets the evaluation requirements.

Abstract:To reduce the seal failure rate of diesel engine crankshaft oil seals,market failure data of a certain platform's diesel engine crankshaft oil seals is statistically analyzed.Using fishbone diagrams,possible causes of oil seal failure and leakage are analyzed from six aspects:human,machine,material,method,environment,and measurement.The root cause of failure is verified through comparative tests of oil seal reliability from different suppliers and oil seal consistency assessment bench tests.On this basis,the improvement measures to reduce the sealing failure rate are proposed and tracked in the market.The results show that the failure rate of oil seals for cement mixer trucks is the highest,and the failure rate of the rear oil seal is significantly higher than that of the front oil seal.The main failure modes of faulty oil seals include main lip line failure,eccentric wear,and felt fuzzing.The main reasons for seal failure are the insufficient of followability of the oil seal and the inadequate density of the rubber material,defective production assembly process,uncoated end caps and gear shaft end faces,and poor assembly performance of combination oil seals.The oil seal parameters are optimized,as well as the injection vulcanization process,gluing on end caps and gear shaft heads,and assembly processes.After improvement,the failure rate of the oil seal market has significantly decreased.

Abstract:An ethanol gasoline(E22)with a volume fraction of 22％ethanol is prepared for a 1.5-liter turbocharged and port fuel injection engine.The pre-ignition characteristics of the E22 engine are studied through experiments.And the effects of low calcium engine oil,injector optimization,and excess air coefficient on the pre-ignition characteristics of the E22 engine are further analyzed.The results show that under low-speed and high load conditions,the pre-ignition frequency of the E22 ethanol gasoline is 1-3 times that of pure gasoline(E0).The use of low calcium engine oil can reduce the frequency of pre-ignition.When the torque is 240 N·m,the pre-ignition frequency of the E22 engine is reduced by 65％compared to conventional engine oil.Increasing the number of fuel injector holes from 4 to 8 and shifting the injection,the pre-ignition frequency of the E22 engine is decreased by 61％compared to before optimization when the torque is 240 N·m.Reducing the excess air coefficient can gradually decrease the frequency of pre-ignition.By using low calcium engine oil combined with optimized fuel injection,the pre-ignition frequency of the E22 engine is significantly reduced,and it passed the pre-ignition test standard.The engine produces a peak torgue of 240 N·m within the speed range of 1 750-4 000 r/min,and achieves a maximum power of 120 kW at 5 500 r/min.

Abstract:To address the issue of significant impact on vehicle terminal data transmission due to varying communication quality across regions and packet loss,this study further optimizes and enhances data transmission quality by designing an asynchronous architecture for data reading,storage,and transmission.Based on TCP protocol caching,a data buffer pool is introduced to separate data reception and transmission processes,enabling data buffering between blind zone storage and real-time transmission modes for vehicle terminals.By comparing data transmission performance before and after implementing this solution across 10 vehicles in different regions,the results show that the asynchronous vehicle-to-cloud data transmission architecture significantly improves data integrity and markedly reduces the impact of signal strength variations.The proposed architecture demonstrates notable effectiveness in enhancing data transmission quality and improves the adaptability of vehicle terminals to varying communication network conditions.

Abstract:To achieve optimal matching between the fuel injection system and the diesel engine,and to improve the engine emissions,fuel economy,and performance,based on the design validation testing of a specific diesel engine injector,this study experimentally investigates the influence of injection pressure and nozzle orifice configuration on diesel engine performance by systematically varying these parameters.The results indicate that the injection pressure and nozzle geometry are decisive factors governing fuel spray pattern and atomization characteristics.Within the high-speed operating range of the engine,increasing the injection pressure improves fuel atomization,enhances combustion efficiency,and effectively reduces the brake-specific fuel consumption(BSFC).Conversely,in the low-speed range under identical injection pressure,injectors with smaller orifice diameters yield relatively lower BSFC,suggesting that the structural parameters of the injector exert a more pronounced influence on fuel consumption in this operational regime.

Abstract:To analyze the correlations among abnormal data in the cold test of a certain diesel engine assembly,an abnormal data analysis method for assembly cold test based on association rules is proposed.This method adopts the KIH-means clustering method to construct an association rule sample library for the diesel engine assembly data.Through the support-confidence test,the optimal combination of minimum support and minimum confidence thresholds is determined.The Apriori algorithm is used for association rule mining to reveal the correlation among abnormal data,and the mining results for the diesel engine assembly anomalies are obtained.The results show that the optimal threshold combination for the diesel engine is a minimum confidence of 0.75 and a minimum support of 0.225％,at which the change in the number of association rules is the most stables.The combination of KIH-means clustering method and Apriori algorithm can determine the association rules of abnormal parameters through data mining of the association rule sample library.On this basis,targeted optimization measures can be effectively proposed,thereby improving the engine assembly quality and the consistency of assembly performance.

Abstract:To address the challenge of health status assessment for diesel engine air systems,when considering their complex structure,high fault frequency,insufficient full-life-cycle data,and difficulties in accurate fault characterization,and to provide support for predictive maintenance,a time-series-based health status assessment method for diesel engines is proposed.Initial health indicators are constructed according to the health status of the air system per unit time.An autoencoder model is adopted to perform feature weighting optimization on the initial indicators for improved characterization accuracy.Combined with the sliding window method,time-series analysis is applied to smooth historical health status data.Finally,a long short-term memory(LSTM)network is established to predict the health status of the diesel engine air system.The results demonstrate that the designed time-series-based assessment method is effective with high prediction accuracy.The mean squared error(MSE)between the predicted and measured results of health status is 2.11×10-5,the root mean squared error(RMSE)is 0.004 6,and the mean absolute error(MAE)is 0.003 1.This method can provide reliable support for the predictive maintenance of diesel engine air systems.

Abstract:In order to solve the problems of high energy consumption and high emissions of offshore platform cranes and improve energy efficiency,considering the cost of power batteries and the irreplaceable typical advantages of diesel engines in safety and reliability,a hybrid power scheme for offshore platform cranes is proposed,which monitored the state of charge(SOC)of batteries and the dynamic load of the crane,the collaborative control strategy is designed,and the simulation verification under the typical working conditions of the crane is carried out.The results show that the fuel consumption and CO2 emission of the heavy duty diesel engine driven by the diesel engine-lithium battery hybrid system are significantly reduced.After 8 h typical operation cycle,the fuel consumption of the traditional diesel engine crane and the hybrid crane are 141.0 kg and 120.2 kg,with the CO2 emissions are 435.7 kg and 371.3 kg,respectively,both the fuel consumption and CO2 emissions are reduced by 14.8％.

Abstract:To solve the problem of idle vibration during vehicle development and identify its causes,idle speed vibration tests and rotating component dynamic balance tests are carried out to analyze the impacts of rotating component dynamic balance and idle speed setting on vibration velocity.An optimization method is adopted by adjusting the dynamic balance and setting the idle speed to 700 r/min.The results show that the vibration velocity of the test point is not satisfied with the test requirement and the problem of idle vibration can not be solved when the spline of the dual clutch is assembled with the spline of the dual mass flywheel by rotating 180° degrees in the original state.The degree of vehicle vibration increases with the rise of idle speed.When the vibration frequency corresponding to the idle speed is close to the rigid body modal frequency of the vehicle powertrain,the vehicle vibration becomes more obvious.When the idle speed is adjusted to 700 r/min,the corresponding vibration frequency is 11.7 Hz,and the vibration velocity at the measuring points meets the test requirements,which is the optimal solution.

Abstract:In order to improve the cold start performance of diesel engine,based on a 2.5L diesel engine with preheating mode of intake heater,a cold start experiment is carried out under extremely cold ambient temperature of-30℃.And the effects of compression ratio,throttle opening,preheating mode and fuel injection control strategy on the cold start performance of diesel engine are studied.The experiment results show that when the compression ratio is 17.0 and the intake heater is used,the diesel engine takes a long time to heat up and consume a lot of power,it cannot be started normally.Increasing the compression ratio and throttle opening can increase the pressure and temperature of the mixture in the cylinder at the end of compression,and improve the cold start performance of diesel engine at low temperature,but the effect is limited.The diesel engine starts quickly with the preheating plug,and the starting time is 3.95 s,which can effectively improve the cold start performance of diesel engine.The relative distance between the glow plug and the fuel beam is usually 0.4-2.0 mm.