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目 录 前 言···························································································· 1 copyright paper51.com 1活塞的概述·················································································· 2 内容来自论文无忧网 www.paper51.com
1.1活塞的功用及工作条件································································ 2 内容来自论文无忧网 www.paper51.com
1.2活塞的材料················································································ 2 copyright paper51.com 1.3活塞结构··················································································· 2 内容来自论文无忧网 www.paper51.com 1.3.1活塞顶部··············································································· 2 内容来自www.paper51.com 1.3.2活塞头部··············································································· 3 paper51.com 1.3.3活塞裙部··············································································· 3 copyright paper51.com 2活塞的结构参数············································································ 4 内容来自www.paper51.com 3活塞最大爆发压力的计算······························································ 5 内容来自论文无忧网 www.paper51.com 3.1热力过程计算············································································· 5 内容来自论文无忧网 www.paper51.com
3.2柴油机的指示参数······································································ 8 copyright paper51.com 3.3柴油机有效效率········································································ 10 内容来自论文无忧网 www.paper51.com 4活塞销的受力分析······································································· 11 http://www.paper51.com
5活塞的加工工艺·········································································· 13 http://www.paper51.com
参考文献：··················································································· 14 copyright paper51.com
内容来自论文无忧网 www.paper51.com 前 言 paper51.com 内燃机的不断发展，是建立在主要零部件性能和寿命不断改进和提高的基础上的，尤其是随着发动机强化程度的提高、功率的增大和转速的增加，零部件尤其是直喷式柴油机活塞的工作环境变得更加恶劣了。活塞的结构直接影响活塞的温度分布和热应力分布，因此就有必要对活塞的结构和性能作出预测和评价。 http://www.paper51.com 活塞是内燃机上最关键的运动件，它在高温高压下承受反复交变载荷，被称为内燃机的心脏，特别是坦克、舰艇和军用车船用内燃机活塞则要求更高，它已成为制约内燃机发展的一个突出问题。 内容来自www.paper51.com 本次课程设计的题目是发动机铝活塞的结构及工艺设计，选择利用合适的机床加工发动机活塞，通过这次课程设计，要求熟练掌握并能在实际问题中进行创新和优化其加工工艺过程。 内容来自论文无忧网 www.paper51.com
1活塞的概述 内容来自www.paper51.com 1.1活塞的功用及工作条件 copyright paper51.com 活塞是曲柄连杆机构的重要零件煤气主要功用是承受燃烧气体压力和惯性力，并将燃烧气体压力通过活塞销传给连杆，推动曲轴旋转对外作功。此外，活塞又是燃烧室的组成部分。 内容来自论文无忧网 www.paper51.com 活塞是内燃机中工作条件最严酷的零件。作用于活塞上的气体压力和惯性力都是周期变化的，燃烧瞬时作用于活塞上的气体压力很高，如增压内燃机的最高燃烧压力可达14—16MPa。而且活塞还要承受在连杆倾斜位置时侧压力的周期性冲击作用，在气体压力、往复惯性力和侧压力的共同作用下，可能引起活塞变形，活塞销座开裂，活塞侧部磨损等。由此可见，活塞应有足够的强度和刚度，而且质量要轻。 http://www.paper51.com 活塞顶部直接与高温燃气接触，活塞顶部的温度很高，各部的温差很大，柴油机活塞顶部常布置有凹坑状燃烧室，使顶部实际受热面积加大，热负荷更加严重。高温必然会引起活塞材料的强度下降，活塞的热膨胀量增加，破坏活塞与气缸壁的正常间隙。另外，由于冷热不均匀所产生的热应力容易使活塞顶部出现疲劳热裂现象。所以要求活塞应有足够的耐热性和良好的导热性，小的线膨胀系数。同时在结构上采取适当的措施，防止过大的热变形。 内容来自www.paper51.com
活塞运动速度和工作温度高，润滑条件差，因此摩擦损失大，磨损严重。要求应具良好的减摩性或采取特殊的表面处理。 http://www.paper51.com |