论文部分内容阅读
当代大型柴油机冷却系统的工作条件比以往更加苛刻,这是因为履带式拖拉机、推土机和铲运机经常在严酷条件下使用。 为了估计由一台建筑机械产生的大量热,用一台履带拖拉机用的225PS柴油机,使其在70％最大负荷条件下运转。该发动机一小时产生的热量足以为一座标准房间加暖一天半。此热量的1/3可转变成功率,1/3由排气管排出,其余的1/3就必须用冷却系统加以冷却。没有冷却系统,发动机将被熔化。反之,发动机过冷运行可能引起润滑不良并产生大量油泥或积炭。在100～120°F条件下运转的发动机,其寿命只有在正常的160～180°F条件下运转的发动机寿命的一半。
The working conditions of today’s large diesel cooling systems are more demanding than ever as tracked tractors, bulldozers and scrapers are often used under harsh conditions. To estimate the amount of heat generated by a construction machine, a 225-PS diesel powered crawler tractor was used to operate at 70% of maximum load. The engine produces enough heat an hour to warm a standard room for a day and a half. One-third of this heat can be converted into power, one-third of which is discharged through the exhaust pipe and the remaining one-third must be cooled by the cooling system. Without a cooling system, the engine will be melted. Conversely, over-cooling the engine may cause poor lubrication and generate large amounts of sludge or coke. Engines that operate at 100-120 ° F have a life expectancy of only half the life of a typical engine operating at 160-180 ° F.