涡轮增压柴油机在瞬态过程中存在喘振问题,影响可靠性和驾驶体验,尤其对于利用进气节流阀提高热管理性能的国六涡轮增压柴油机,其喘振问题亟待解决。试验对象为排量10.5 L的重卡发动机,进行不同发动机转速下突降油门试验,通过对比发现发动机在中低转速突降油门过程更容易发生喘振;另外,进行热管理模式下不同进气节流阀关闭速度和最小关闭开度的突降油门试验,通过对比喘振规律发现,热管理模式下进气节流阀关闭速度越快,进气阻塞作用越强,而进气节流阀最小开度越小,最小折合流量越小,喘振风险越大。在空气系统模型基础上搭建喘振控制策略,经过验证可知,热管理模式下喘振控制策略能有效防止突降油门过程超出喘振线,一定程度上解决了国六涡轮增压柴油机喘振问题。
There exists surge problem for turbocharged diesel engine in the transient process, which affects reliability and driving experience. The surge problem needs to be solved urgently, especially for China Ⅵ turbocharged diesel engine that uses intake throttle valve to improve thermal management performance. A heavyduty truck engine with a displacement of 10.5 L was used to conduct a throttle sudden drop test at different speeds. By comparison, it was found that the engine is more prone to surge in the process of throttle sudden drop at medium and low speeds. The throttle sudden drop test was further conducted based on different inlet throttle valve closing speeds and minimum closing openings in thermal management mode. By comparing the surge law, the fast closing speed of the inlet throttle valve would lead to the stronger blocking effect of intake, the small minimum opening would lead to the smaller minimum folded flow, and the risk of surge hence became large. Then the surge strategy was proposed based on air system model and was verified. The results show that the surge strategy in thermal management mode can effectively prevent overpassing the surge line in the process of throttle sudden drop, which solves the surge problem of China Ⅵ turbocharged diesel engine that using the intake throttle valve to some extent.