Dynamics Analysis Of The Crankshaft And Connecting Rod Mechanism Of The Internal Combustion Engine With Piston-pin Clearance

With the development of modern science and technology, mechanical industry has got a rapid development. How to ensure that the mechanism operates effectively and stable becomes an important research content of the modern industrial development. However, in the operation of mechanism, the motion-pair inevitably exists clearance, it will not only affect the dynamic prediction, but also bring friction on the surface of the motion-pair, even cause wear and tear to make the mechanism failure eventually. So carrying out the research on the dynamical theory of the clearance problem will provide effective analysis and solution methods for the design of modern mechanism and dynamics analysis of the mechanism, and also has important value in engineering.Firstly the research background and the latest progress of the clearance problem are reviewed in the paper. The dynamic characteristics of the piston-connecting rod-crankshaft system of the internal combustion engine with piston-pin clearance are analyzed. Secondly, basing on the theory of impact-function, the mathematical model of the clearance between piston and piston-pin has been built. The theory of the dynamic multibody systems and mechanical simulation software ADAMS are used to build the dynamical model. Thirdly, basing on the theory of dynamics of multi-rigid-body systems, the acceleration and velocity for the piston and the orbit for the piston-pin with both clearance and no clearance are analyzed, and the influences of the dynamic behavior of the system changed by the collision of piston-pin clearance are investigated. The results show that the mechanism responses are greatly influenced by the clearance, and piston-pin has three types of movement changing:free movement, continuous contact and impact movement. There are many sharp peaks on the piston acceleration curves when the piston reaches top dead center (TDC) and bottom dead center (BDC). The impact action of system has been greatly increased when the rotational speed is higher and the clearance is larger. Finally, the finite element model of flexible connecting-rod and flexible piston-pin have also been built to study the influence of flexible factor on the dynamical behavior of the mechanism. The piston-connecting rod-crankshaft system of the single cylinder engine has been built and analyzed basing on use the theory of flexible multibody dynamics and the method of Craig-Bampton. Compared with the simulation curves in the case of rigidity, the results shows that flexible factors has played a relaxation effect on the dynamic behavior of the mechanism...