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一、概况 我国向美国GE公司购买的ND5机车配用该公司生产的四冲程、V型、缸径228.6毫毫、行程266.7毫米7FDL柴油机。它自1956年首次从V型7FAL柴油机投入铁路运用以来,经过长期的试验改进,已经把柴油机的公升功率提高到相当高的水平,发展为性能指标先进、强化程度高的7FDL柴油机。从7FAL发展到7FDL的每次变革改进都是从活塞组件开始的。最初的活塞为整体铸铁振荡冷却结构,冷却油通过主:副连杆的止回阀流入连杆体的油孔,再经活塞销上的钻孔进入摇摆式振荡腔,整个活塞配制4道气环、3道油环(见图1)。这一结构的活塞经过11.2～16万公里的运行,机油耗量为燃油耗量的 2％左右,顶环发现拉毛。第一次改进是在铸铁活塞上进行,主要取消裙部第三道油环(见图 2)。这样顶环的寿命提高到24～32万公里。第二次改进仍在铸铁活塞上进行,主要是降低顶环位置和取消第二道油环(见图3),这样使顶环的温度显著下降,寿命提高到56～72万公里,机油耗量为燃油耗量的0.6～0.7％,平均有效压力从14.3kgf/cm~2提高到17.gkg/cm~2,在上述铸
I. Overview China to the United States GE company to buy the ND5 locomotive equipped with the company’s four-stroke, V-shaped, bore 228.6 mill milliliters, travel 266.7 mm 7FDL diesel engine. Since it was put into operation for the first time by the V-7FAL diesel engine in 1956, it has raised the liter power of diesel engines to a rather high level after a long trial and improvement and has developed into a 7FDL diesel engine with advanced performance and high degree of strengthening. Every change improvement from 7FAL to 7FDL starts with the piston assembly. The first piston for the whole cast iron oscillation cooling structure, the cooling oil through the main: Vice-link check valve into the connecting rod oil hole, and then through the piston pin into the rocking oscillation cavity, the entire piston preparation 4 gas Ring, 3 oil ring (see Figure 1). This structure of the piston after 11.2 to 16 million km of running, fuel consumption of about 2% of fuel consumption, the top ring to find Mao Mao. The first improvement is carried out on the cast iron piston, the main cancel the skirt third oil ring (see Figure 2). This top ring life increased to 24 to 32 million km. The second improvement is still on the cast iron piston, mainly to reduce the top ring position and cancel the second oil ring (see Figure 3), so that the top ring temperature dropped significantly, life expectancy increased to 56 to 720,000 km, fuel consumption The amount of fuel consumption of 0.6 to 0.7%, the average effective pressure increased from 14.3kgf / cm ~ 2 to 17.gkg / cm ~ 2, the above cast