基于目标起动转速变化规律的起动过程瞬态喷油量控制策略研究

提出了一种基于目标起动转速变化规律的起动过程瞬态喷油量的控制策略以改善柴油机起动性能,详细介绍了这种控制策略的起动过程瞬态喷油量的确定方法,并在2.8T型4缸直喷高压共轨柴油机上与恒定油量控制方法和标定转矩MAP控制方法进行了台架对比试验。结果表明:标定转矩MAP控制方式虽然NO_x排放量最低,但燃烧效率普遍较低,HC与CO排放水平较高;而基于目标转速变化规律的控制策略可根据起动过程中目标转速的变化所对应的需求转矩精确地控制起动过程各循环的瞬态喷油量,实现对起动过程喷油量的循环控制,使各循环燃烧效率均保持在高水平,有效地降低了CO_2排放,且在保持HC和CO排放水平较低的前提下明显降低了NO_x排放量,同时很好地改善了起动到怠速的过渡过程转速的波动现象。

Research on the Transient Injection Quantity Control Strategy Based on the Target Engine Speed Curve During the Start Process

Focued on the diesel engine starting injection quantity control strategy based on the target engine speed curve, the calculation of target indicated torque was introduced in detail, and the comparison tests between constant injection quantity control, torque MAP control and the researched target speed based torque control was conducted. The result shows that although the NOx emission of the torque MAP control is the lowest among the three control modes, the combustion efficiency is obviously lower than others and the HC as well as the CO emission is at a fairly high level. Fewer fuel is consumed in the target speed based torque control because the injection quantity is controlled with great accuracy according to the indicated torque in need during diesel engine starting process, so that the combustion efficiency is the highest and the CO2 emission is the lowest among the three control modes. The HC and CO emissions of target speed curve based torque control is at a similar level as the constant injection quantity control. However, when it comes to the engine speed stability and the NOx emission, the target speed curve based torque control shows an overwhelming predominance.