电辅助涡轮增压器对柴油机热效率调控规律的研究

针对一台配备有电辅助涡轮增压器(electrically assisted turbocharger,eTurbo)的6.7L柴油机,建立并试验校准了其GT-SUITE/Simulink联合仿真平台。通过调节eTurbo的电功率,在保持发动机动力性不变的前提下,改变发动机的运行状态,以获得发动机系统的电能平衡和最大热效率。基于该平台,首先在稳态工况下,研究了eTurbo的电功率与发动机热效率之间的相互影响关系,并在全工况内量化评估了发动机等效热效率的改善潜力。其次开展了US06城市工况及FTP-75市郊驾驶循环工况下的仿真分析,循环平均结果显示:随电辅助能量的增加,发动机热效率提高但回收的电能不断减小;在FTP-75循环下,要实现发动机节油就必须使用额外的发电手段,比如回收整车刹车能量;与FTP-75循环相比,US06循环发动机负荷更高,故可回收更多的电能,电能可以实现自平衡。

Study on Regulation of Thermal Efficiency of Diesel Engine Equipped with Electrically Assisted Turbocharger

A GT-SUITE/Simulink simulation platform was established and tuned for a 6.7 L diesel engine equipped with electrically assisted turbocharger (eTurbo) to study how to regulate electric power for the eTurbo to achieve electric energy balance and optimum engine equivalent thermal efficiency on the basis of keeping engine dynamic performance unchanged. First, based on the simulation platform, the interaction between eTurbo power and engine thermal efficiency at steady state condition was studied, and the engine equivalent thermal efficiency was evaluated at all operating conditions. Then, a simulation was conducted with FTP-75 and US06 driving cycles. The results indicate as follows: with the increase of assistant energy, engine thermal efficiency increases by up to 2.95% in the FTP-75 cycle and by up to 1.08% in the US06 cycle, while the regenerated energy keeps decreasing by up to 93.1% in electricity deficit. In the FTP-75 cycle, additional energy, such as one recovered from braking, should be provided for an eTurbo engine to save fuel.Compared with the FTP-75 cycle, more energy can be recovered in the US06 cycle due to higher load, thus achieving an electric energy balance.