发动机连杆衬套过盈装配仿真及分析

发布时间：2018-07-16 08:46

【摘要】：发动机作为一种动力源,是当今用量最大、用途最广的动力机械之一。随着经济及科技的发展,发动机技术的发展也日新月异。连杆是发动机的核心传力部件之一,在工作过程中,承受着不断变化的周期性燃烧压力和惯性力的交变载荷,机械负荷严重,工作条件恶劣。连杆的可靠性一直是人们在发动机研究和改进过程中关注的热点问题。为避免连杆小端的应力集中现象,在连杆小端压入滑动轴承——衬套,二者的配合属于厚壁圆筒与薄壁圆筒的过盈配合。传统的过盈配合理论都是以厚壁圆筒为模型,这些理论对于连杆小端与衬套的过盈配合并不适用。长期以来衬套的安装都是凭借经验完成的,缺少一个可靠的理论支持体系。本课题将针对某特定型号发动机进行分析,得出其过盈配合的合理过盈量,并推广到此类模型的过盈配合,研究工作主要包括以下内容: 1)对连杆小端与衬套过盈配合的模型进行简化,将二者分别简化为厚壁圆筒及薄壁圆筒; 2)在现有的厚壁圆筒理论基础上,对薄壁圆筒的受力情况作合理假设,以Lame公式为基础,推导出薄壁筒受外压时的应力应变公式以及厚壁圆筒与薄壁圆筒过盈配合的过盈量计算公式; 3)分析某型发动机在工作过程中的受力情况,计算连杆小端在承受最大载荷时衬套与连杆小端所需的最小结合压力,以及为保证连杆及衬套不发生塑性变形允许的最大结合压力,据此得出过盈量的数值范围; 4)利用ANSYS软件对此过盈配合进行仿真分析,得出不同过盈量下的最大等效应力及接触应力,与理论值进行比较,验证理论计算的正确性,及ANSYS软件的实用性; 5)编写ANSYS程序,对此类过盈配合进行参数化设计,以推广到其余的机型。研究的结果表明,推导出的厚壁筒与薄壁筒过盈配合过盈量的计算公式对连杆小端与衬套是适用的,且通过ANSYS软件可以对此类问题实现参数化设计。
[Abstract]:As one kind of power source, engine is one of the most widely used power machines. With the development of economy and science and technology, the development of engine technology is changing with each passing day. Connecting rod is one of the core force components of the engine. In the working process, the alternating load of the changing periodic combustion pressure and the inertia force is carried out. The mechanical load is serious and the working conditions are bad. The reliability of the connecting rod has always been a hot issue in the process of engine research and improvement. In order to avoid the stress concentration in the small end of the connecting rod, the sliding bearing - bushing is pressed into the small end of the connecting rod. The combination of the two is the interference of the thick wall cylinder and the thin-walled cylinder. The theory is based on thick wall cylinder, and these theories are not applicable to the interference combination of the small end and the bushing of the connecting rod. For a long time, the installation of the bushing is completed by experience and lacks a reliable theoretical support system. It has been extended to interference fit of such models.
1) simplify the model of interference fit between the small end of the connecting rod and the bushing, and simplify the two parts to the thick wall cylinder and the thin wall cylinder respectively.
2) on the basis of the existing thick wall cylinder theory, the stress situation of the thin-walled cylinder is assumed reasonable. Based on the Lame formula, the stress and strain formula of the thin-walled cylinder under external pressure and the calculation formula of the interference of the interference fit of the thick wall cylinder and the thin wall cylinder are derived.
3) to analyze the force situation of a certain type of engine during the working process, to calculate the minimum binding pressure required by the small end of the connecting rod and the small end of the connecting rod, as well as to ensure the maximum combination pressure of the connecting rod and the bushing without plastic deformation, and then the numerical range of the interference amount is obtained.
4) use ANSYS software to simulate the interference fit, get the maximum equivalent stress and contact stress under different interference amount, compare with the theoretical value, verify the correctness of the theoretical calculation, and the practicability of the ANSYS software.
5) write the ANSYS program and parameterize this kind of interference fit in order to spread to the other models. The result of the study shows that the formula for calculating the interference fit between thick wall tube and thin wall cylinder is applicable to the small end and bushing of the connecting rod, and the parameterized design can be realized through the ANSYS software.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH131.7

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