低气压对发动机轴承性能的影响

Study of the Influence of Low Environment Pressure on the Bearings in Internal Combustion Engine

以立式单缸柴油发动机为研究对象,分析了低气压对发动机主轴承和连杆大端轴承工作情况的影响。首先建立了考虑气压影响的单缸发动机模型,然后通过实验测得发动机在不同环境气压下气缸内的燃气压力,将此压力作为载荷加载到单缸发动机模型上,利用AVL公司提供的商用软件EXCITEDesigner计算得出主轴承和连杆大端轴承的载荷、偏心率和摩擦功率损失。计算结果表明:随着环境气压的降低,发动机的主轴承和连杆大端轴承载荷减小,转速越高载荷减小幅度越大;在转速较低时,随环境气压减小,偏心率的形状变小,轴承工作更稳定,在转速较高时,随环境气压减小,偏心率的形状反而变大,工作不稳定;主轴承和连杆大端轴承摩擦功率损失随着气压减小略有减小。最后,通过实验对计算模型进行了验证。

The influence of low environment pressure on the main bearing and big end bearing of internal combustion engine was investigated based on a one-cylinder diesel engine. A model of one-cylinder engine was set up by the use of the commercial software EXCITE Designer from AVL company. A series of experiments were done to gain the gas pressure in cylinder under different environment pressure. When the model of the engine considered the gas pressure as load, the applied load, eccentricity ratio and friction loss of the main beating validated by the experiments. The calculation results show and the big end one were calculated, and the results were that, with the decrease in environment pressure, the applied load of main bearing and big end one is decreased, the higher the rotate speed and the greater the applied load decreases. With the decrease in environment pressure, eccentricity ratio increases, while their friction loss decreases a little.