| With the increasingly serious global environmental problems and the continuous depletion of energy, it has become an inevitable trend to improve the engine performance and research a new engine with high-efficiency and low power consumption. As the main powerhouse of the engine, crankshaft-connecting rod-piston system in the complete machine occupies an extremely important position. Its dynamic properties direct impact on the reliability and durability of the engine. Therefore, it is very important to do dynamic analysis of the crankshaft-connecting rod-piston system which is a core component in a new engine. In this paper, aiming to a special crankshaft-connecting rod-piston system of a new engine, the author did research on the dynamic model and numerical simulation to obtain the dynamic parameters.This paper analyzed the research status of the crankshaft-connecting rod-piston system dynamic model inland and overseas and stated the characteristics of the new engine. Based on this, the author did thorough research on secondary motion of the piston, the hydrodynamic lubrication model between piston and cylinder liner, crankshaft and base bearing, the three-dimensional model of overall system and so on. First of all, kinetic and dynamic analysis of piston, crankshaft and connecting rod as three main parts was given respectively. The impact of the piston secondary motion was the key point to consider. In this part, the author established the dynamic model of the crankshaft-connecting rod-piston system, and then, set up hydrodynamic lubrication model of crankshaft-base bearing system and piston-cylinder liner system. On the basis of this, the above models were integrated to obtain the total model of the overall system. After the establishment of the dynamic model, select the appropriate algorithm to do numerical solution according to the characteristics of each model. In the process of simulation, do some simplification works on the model in the light of actual working condition. And then, import geometric parameters, physical parameters, working conditions in line with Pro/e model to simulate the dynamic model with computer programming. In this paper, the author used Fortran programming language which is common a project. In the process of programming, write subroutine used for solving partial model first, loop through the subroutine call afterwards to obtain the final results. Through the modeling and the numerical simulation, this new engine’s dynamic parameters can be obtained. The conventional dynamic parameters are quite orderly and studies have the conclusion. Therefore, in this thesis, the author emphasized on the analysis of the law of the piston secondary motion, the crankshaft radial motion, the force of oil film imposed on the piston in the crankshaft liner and the force of oil film imposed on the crankshaft in the main bearing. Through the analysis of these rules, the factors which affect the change of these rules are obtained. Thus, we can learn about the factors which affect the engine dynamic performance in the work process. Meanwhile, combined with the project team’s simulation results of this model using Adams software, we made necessary amendments to the model, then, compared and validated the results of numerical simulation. |
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