范振阳，杨建国，刘然

(哈尔工业大学（威海）,山东 威海 264209)

    摘要：某型汽油机匹配废气涡轮增压后的实验数据显示，虽然实现了动力性地显著增加，但是燃油经济性有较大幅度的下降。本文分析了该问题产生的原因，提出了采用外部冷却EGR的解决方法。建立了GT-Power仿真模型，进行了外特性下的仿真计算分析，结果表明：采用EGR能够抑制爆震，降低排气温度，从而通过优化点火时刻、进气压力和空燃比来实现发动机目标输出扭矩基本不变的同时，有效地解决了汽油机增压后所带来的燃油经济性变差的问题。在5%EGR率条件下，平均有效燃油消耗率降低约10%。

    关键词：汽油机；废气涡轮增压；EGR；燃油经济性；动力性

    Abstract: These experimental data shows that turbocharging increases the power output significantly, while the fuel economy declines greatly. In this paper, the reasons of this problem are analyzed, and external cooled EGR is proposed as a solution to the problem. A simulation model is established by using the software GT-Power, and then the model is used to conduct the engine performance simulation analysis at WOT operation. Simulation shows that, with an EGR ratio of 5 percent, the EGR can depress knock resistance and drop exhaust gas temperature. Optimizing  four main parameters, the power output can be recovered and the average brake specific fuel consumption decreases by 10 percent approximately, which can reach the level without a supercharger being applied.

    Key Words: SI Engine; Exhaust Turbocharging; EGR; Engine Performance