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曲轴是往复式发动机的心脏,现代高功率汽车发动机要求它有高度的可靠性。在某些情况下,高的可靠性可通过改进发动机和曲轴的设计来实现。例如高速V—8汽油机采用有五个主轴颈和大圆角半径的短而粗的曲轴,以便能将曲轴应力降低到这种状况:即使是未经热处理的锻钢曲轴、球铁或珠光体可锻铸铁曲轴也有足够的强度来传递在燃烧室内所产生的力。某些直列式汽油机也采用了铸造曲轴,在设计上用增加主轴颈数、圆角半径和加大主轴颈与连杆轴颈间金属厚度而得到低应力。
The crankshaft is the heart of a reciprocating engine, which demands high reliability in modern high-power automotive engines. In some cases, high reliability can be achieved by improving the design of the engine and crankshaft. For example, a high-speed V-8 gasoline engine uses a short, thick crankshaft with five main journals and large fillet radii to reduce crankshaft stress to the condition that even forged steel crankshafts without heat treatment, ductile iron or pearlite malleable iron The crankshaft also has enough strength to transmit the force generated in the combustion chamber. Some in-line gasoline engines also use cast crankshafts, which are designed to achieve low stress by increasing the number of primary journals, fillet radii, and increasing the thickness of the metal between the main journal and the connecting rod journal.