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Based on the sample data obtained from the bench test of a four-cylinder naturally aspirated CNG engine, three different machine learning models, BP, SVM and GRNN, were used to develop the intake charge prediction model for the intake system of this engine, in which engine speed, intake manifold pressure and intake temperature, VVT angle and gas injection time were taken as input parameters and intake charge was used as output parameter. The comparative analysis of the experimental data and model prediction data showed that the mean absolute error (MAE) of BP model, GRNN model, and SVM model were 2.69, 8.11and 5.13, and the root mean square error (MSE) were 3.53, 9.29, and 7.17, respectively. BP model has smaller prediction error and higher accuracy than SVM and GRNN models, which is more suitable for the prediction of the intake charge of this type of four-cylinder naturally aspirated CNG engine.

Ethanol reforming gas combined with EGR technology can not only improve thermal efficiency, but also reduce pollutant emission under lean combustion condition. In this investigation, GT-Power is used to carry out one-dimensional simulation model calculation and analysis to explore the combustion characteristics, economy performance of a direct injection gasoline engine when the excess air coefficient (λ) increases from 1 to 1.3 and the ethanol reforming gas mixing ratio increases from 0% to 30% at the working condition of 2000 r/min and 10 bar. Then the EGR system is introduced to deeply discuss the working characteristics of the direct injection gasoline engine when the EGR rate increases from 0% to 20%. The results show that the increase of λ leads to the decrease of in-cylinder pressure and the delay of the peak of cylinder pressure.

This paper aimed at a gasoline engine "cylinder head- cylinder gasket-cylinder body-bolt" sealing system, built the 3D solid model and the finite element model of the assembly, and calculated the stress and strain of the cylinder gasket under the cylinder pressure and the deformation of the engine block. In addition, based on the calculation results, this paper put forward the optimization scheme of the cylinder gasket structure, re-established the simulation model, and get the calculation results. The calculation results showed that the cylinder pressure had influence on the sealing performance of the cylinder gasket, and the influence of cylinder pressure should be taken into consideration when designing the cylinder gasket. When the cylinder pressure was applied, the overall contact stress of the cylinder gasket had decreased, and the whole remaining height of the gasket had increased.

Sealing system is an important subsystem of modern high-performance engine. Sealing system reliability directly affects the engine operating conditions. Cylinder head gaskets(CHG) sealing system is of the most importance to the engine sealing system, which is not only responsible for sealing chamber, the cooling fluid and lubricating oil passage, for preventing gas leakage, water leakage and oil leakage, but also responsible for force transferring between cylinder head and cylinder body. Basing on nonlinear solution method, the sealing performance of multi-layer-steel cylinder head gaskets to a gasoline engine is studied with the finite element software ABAQUS. The deformations of the cylinder liners and engine block are also considered.

Turbocharger is an important method to improve fuel economy of internal combustion engines. Traditional turbocharger matching methods show their limitations that only consider the matching between turbocharger and engine under the single designed operating point. This paper is to study the turbocharger matching based on vehicle performance requirements, in which performance requirements among vehicle, engine and turbocharger system are fully considered. The study is based on a vehicle which is equipped with 1.5L Chinese produced engine. Vehicle powertrain and gasoline engine simulation models were built in one-dimensional simulation software and verified by experiments. According to the vehicle performance, to study the matching under multiple working conditions, new European drive cycle (NEDC), full-load condition and high altitude condition, the matching of four kinds of turbochargers with a gasoline engine were compared respectively.