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目前,柴油机正在向降低燃油消耗率,提高功率和采用多种燃料(例如燃用重油)的方向发展。随着这一发展趋势,柴油机零部件面临着提高负荷和温度的工作条件。在承受着热负荷的同时承受着机械负荷的柴油机燃烧室零部件要求有高的可靠性。排气门是承受最高工作温度的零件之一,与其它零部件相比,其工作条件也更为苛刻。作者们对改善在上述条件下工作的排气门的可靠性进行了研究。为了降低机械应力,特别是排气门头部的机械应力,采用了有限元计算法,并推荐采用气门头部的形状优化。对使用重油燃料的排气门的耐蚀性进行了实验室试验和在试验发动机上的试验。迄今为止,采用Nimonic合金(镍铬系合金)气门是解决耐高温应力和耐腐蚀性的最好方法之一。
Diesel engines are currently being developed to reduce fuel consumption, increase power and use multiple fuels, such as heavy fuel oil. With this trend of development, diesel engine parts are facing working conditions of increasing load and temperature. Diesel engine combustion chamber components subjected to mechanical loads while subjected to thermal loads require high reliability. Exhaust valve is to withstand the highest working temperature of the parts, compared with other parts, the working conditions are more demanding. The authors studied the improvement of the reliability of exhaust valves working under these conditions. In order to reduce the mechanical stress, especially the mechanical stress of the exhaust valve head, the finite element method is adopted and the shape optimization of the valve head is recommended. Laboratory tests on corrosion resistance of exhaust valves using heavy oil fuels and tests on test engines were conducted. To date, the use of Nimonic alloy (nickel-chromium alloy) valve is to solve the high temperature stress and corrosion resistance of the best way.