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排放法规限值的日益收紧对发动机的各项研发工作提出了新的挑战。为了满足改进燃烧和提高发动机效率的要求,导致发动机的负荷增加和磨粒尺度增大。改进发动机会导致活塞环及活塞环槽面临苛刻的摩擦学条件,因而活塞环端面磨损正成为活塞环设计时要解决的关键问题。防止活塞环端面磨损最常用的方法是镀铬。但这种方法在耐久性(厚度太薄)和金相图(表面粗糙)上有一定的局限性。为此,现已开始采用氮化处理的不锈钢第1道活塞环,以改善对端面的保护。与镀铬层相比,氮化层的硬度较高,且比较光洁。然而,对于新一代载重车发动机而言,在某些情况下,采取氮化处理应对摩擦学条件的能力也有其局限性。一种新的解决办法是采用热喷涂工艺。这种工艺能增加保护层厚度,从而减少活塞环与活塞环槽的磨损。为了在严酷的工作条件下评价各种端面磨损解决方案的效果,设计了特殊的发动机试验程序。对各种活塞环技术的评定结果显示,热喷涂的性能最佳。长期试验结果也显示,热喷涂层能提高端面的耐久性。
The increasing tightening of emission regulations limits new challenges for various engine research and development efforts. In order to meet the requirements of improving combustion and improving engine efficiency, engine load increases and abrasive grain size increases. Improving the engine will result in harsh tribological conditions on the piston ring and the piston ring groove. Therefore, the wear of the piston ring end face is becoming a key issue in the design of the piston ring. The most common method of preventing piston ring end wear is chrome plating. However, this method has some limitations in terms of durability (too thin a thickness) and metallography (rough surface). To this end, nitrided stainless steel first ring rings have now been used to improve the protection of the end faces. Compared with the chrome layer, nitride layer hardness higher, and more smooth. However, for a new generation of truck engines, the ability to deal with tribological conditions by nitriding also has limitations in some cases. A new solution is the thermal spray process. This process can increase the protective layer thickness, thereby reducing the piston ring and piston ring groove wear. In order to evaluate the effectiveness of various end-wear solutions under harsh working conditions, special engine test procedures have been devised. The assessment of various piston ring technology results show that thermal spraying the best performance. Long-term test results also show that the thermal spray coating can improve the durability of the end face.