排气制动对增压器涡轮轴向载荷影响的研究

摘要

In this paper, the working states of turbocharger in exhaust braking condition are analyzed for the vehicles concurrently adopting exhaust braking and turbocharging. Through a linked test with both exhaust bra-king and turbocharging functioning, the boundary conditions required for numerical calculation are obtained, and based on which the axial forces of turbine in both steady and transitional conditions are calculated. The results show that in exhaust braking condition, the axial force of turbine reverses its direction, and the higher the exhaust back-pressure the larger the axial force. In the process of working condition switching, the turbine is subjected to high shock load with a highest value up to 221N, and the shorter switching time and higher back pressure will lead to a greater impact load. Hence selecting a reasonable backpressure and an appropriate witching strategy can effectively reduce the axial load of turbine.%本文中针对同时采用排气制动和涡轮增压的车辆,分析其在排气制动工况下增压器的工作状态。通过排气制动与增压器联动试验得出数值计算所需的边界条件,并据此计算涡轮转子在稳态工况和过渡工况的轴向受力。结果表明,在排气制动工况下,增压器涡轮转子的轴向受力反向,且排气背压越高,涡轮转子所受轴向力越大；在工况切换过程中,涡轮转子所受突变载荷较大,最高值达221N,工况切换时间越短、背压越高,轴向冲击载荷越大。因此确定合理的排气背压和工况切换策略可有效降低涡轮转子所承受的轴向载荷。