【作者】 李希斌；

【导师】 李威萱；

【作者基本信息】 武汉理工大学 ， 机械工程， 2002， 硕士

【摘要】 随着现代社会生产力的发展和科学技术的不断进步，内燃机的发展出现了向大功率、高转速和高可靠性方向发展的趋势，因此对内燃机的设计提出了新的更高的要求。特别是近年来，随着人们环护意识的增强，内燃机的振动、噪声以及有毒、有害气体的排放也越来越受到严格的限制。作为内燃机动力传递机构的活塞连杆机构，由于在周期性的工作循环中，承受着强大的气体作用力，往复惯性力、离心惯性力等的冲击，极易引起振动和噪音；同时由于运动副间隙的存在加大了振动的影响，恶化了机构的动态性能。因此对内燃机活塞、连杆机构的运动弹性动力分析具有十分重要的现实意义。 本课题基于现代机械弹性动力学理论以及有限元分析方法，利用美国SDRC公司的Ⅰ-DEAS软件，对含运动副间隙的柴油机的活塞、连杆机构建立了动力学模型；运用KED分析中的“瞬时结构”假定，计算出了机构在各瞬时结构条件下的动态响应，从而为柴油机优化设计提供了可靠的理论依据。活塞裙部形线是活塞的关键结构之一，它的好坏直接影响发动机工作可靠性，以往的判定方法只有在活塞加工完成后，才能通过实验方法判定设计，能否满足工程实际的需要，本文通过KED方法与有限元接触方法的结合，模拟实际活塞工作情况，较为准确的反映出，活塞裙部的变形规律，在设计阶段发现活塞裙部的设计结构问题，节省新产品开发成本，缩短开发周期。本文的工程实践证明，这种思路，是可行的，对LR4100活塞的模拟分析，与实际情况基本相符。本方法具有工程实用价值。通过实践得出如下结论： 1．本课题采用有限元技术，在装配环境中实现模拟了对活塞形线进行评价，利用计算机与接触力学相结合，探索了一条活塞形线确定与评价的新方法。 2．本文采用实体建模，建立了多种真实活塞形状与形线，结合现有的实验和实际使用结果，归纳出了活塞形线的评定方法，大大降低了活塞的开发费用，缩短了定型周期，具有一定的经济效益和社会效益。更多还原

【Abstract】 Accompanying with the development of productive force in modern society and the improvement of science and technology, a trend of high power, high velocity and reliability appears in the field of Internal combustion engine, so the design of internal combustion engine is facing the new challenge. In recent years, with the strengthening of the people’s concept in environment protection, the vibration, noise and the emission of exhausted gases are restricted more and more seriously. Piston-linkage mechanism ,as the mechanism to transfer the power of engine, bearing the heavy gas-explosive force, inertial force etc, is easy to arise vibration and noise. Besides, the joint clearance in mechanism could also irritate the vibration and worsen the dynamic properties of mechanism. So the kineto-elasto-dynamic analysis to the piston-linkage mechanism of internal combustion engine has obvious realistic significance.This thesis, on the basis of modern theories of vibration, KED analysis and finite element method, sets up a kinetic model of piston-linkage mechanism of diesel engine, by I-DEAS software of SDRC USA, which involves the effect of joint clearance in mechanism. By the presumption of "transient structure" in KED analysis, the mechanism’ s dynamic responses in every transient structure conditions are calculated, and it provides a reliable theory basis for the optimization design of diesel engine.The form of piston skirt is the key structure for piston. It directly affects the engine’s working reliability whether it’s good or not. According to the past method , piston can only be decided whether it meets the need of engineering in test after it has been turn out .This paper simulates the real working condition of piston by combining the KED method and FE-contact analysis way .It reflects deforming rule of piston ,and makes it possible that the structure problem of piston skirt can only be found during the design period ,so the cost of developing new product is lowered and the time is shorted .This paper proves that the thought is practical and the result of simulation to piston LR4100 is in accord with practice. Above all , this method has practical value in engineering . and the following condition can be made from practicing.1. This paper realizes the evaluation of piston skirt form in condition of assembly by the way of finite element technology. IT combines the computer technic with contact mechanics and discovers a new way to evaluate the piston form .2. This paper sets up a solid model with multiple real piston skirt form. It sums up a evaluating way to piston form by testing result. For the piston developing cost and time is largely lowered, it has obvious efficiency both in economy and society.更多还原