相继增压系统切换过程对增压器辅推轴承轴向力影响与轴承优化研究

Influences of Switching Process of Successive Turbocharging Systems on Axial Force of Booster Auxiliary Bearing and Research on Bearing Optimization

采用数值仿真方法研究基本增压器在系统切换过程中的轴向力变化规律,并提出了辅助推力轴承的改进设计方法。首先数值仿真研究了基本增压器的转子系统在切换时的压气机/涡轮关键典型截面气动参数分布情况,分析了在柴油机增压模式切换过程中基本增压器转子轴向力大小和方向变化规律,然后提出了增加轴承承力面及改变承力面材料的优化方案。结果表明:基本增压器辅助推力轴承在切换的5 s时间内轴向力发生翻转,最大约承受2273 N的反向轴向力,是造成切换过程辅助推力轴承磨损的关键原因;优化方案最大承载能力为优化前的4.8倍,显著提升了辅助推力轴承承载力。经增压器平台可靠性验证,改进后的增压器辅助推力轴承在相同时间内未出现碰磨现象。

The variation law of the axial force of the basic supercharger during system switching was studied by the numerical simulation method,and the improved design method of the auxiliary thrust bearing was put forward.The distribution of aerodynamic parameters of key typical sections of compressor/turbine when the rotor system of the basic supercharger switched was studied by numerical simulation,and the variation law of axial force and direction of the rotor of the basic supercharger during the switching of diesel engine supercharging mode was analyzed.Then the optimization scheme of increasing bearing surface and changing bearing surface material was put forward.The results show that the axial force of the auxiliary thrust bearing of the basic supercharger turns over within 5 s,and it bears about 2273 N reverse axial force at most,which is the key reason for the wear of the auxiliary thrust bearing during the switching process.The maximum bearing capacity is 4.8 times of that before improvement,which significantly improves the bearing capacity of auxiliary thrust bearing.After the reliability verification of the supercharger platform,rubbing phenomenon did not appear for the improved supercharger auxiliary thrust bearing in the same time duration.