基于窗口观测的电控柴油机判缸控制的优化分析

柴油机起动初期控制时序的建立过程(判缸控制)直接决定其起动过程的长短,判缸控制是电控柴油机管理系统中最核心的部分。为了缩短判缸时间,提高控制系统的可靠性,该文根据目标柴油机的发火顺序设计了电控系统的转速信号与相位,采用了2套转速计算装置;基于有限状态机,提出了窗口观测联合判缸方法,并开发了电子控制单元(electronic control unit,ECU)复杂驱动层的联合判缸驱动控制软件。试验结果表明该策略是有效可行的,发动机的起动成功率提升10%,达到100%,正常起动成功的时间由1.5 s缩短到1 s以内,改善了电控柴油机的起动性能。该控制策略的实现完善了电控柴油机的时序控制功能,提高了柴油机的电控水平。

Optimal analysis for cylinder recognition control of electronically controlled diesel engine based on window checking

Abstract: A complaint against the electronic control diesel engine is that it starts "one second slower" than other conventional mechanical pump diesel engines. That is because that on conventional mechanical pump diesel engines, the phase position between the fuel supply sequence of fuel systems and fuel pump cams is fixed in the starting process and there is no need to cylinder recognition. While on the electronic control diesel engine, the controller cannot determine the specific phase of diesel engine until it receives a sufficient number of crank and cam signals, so as to need cylinder recognition. The establishment process of the control timing sequence at the beginning of the starting (cylinder recognition control) is directly determining the duration of the diesel engine starting process. The cylinder recognition control is one of the most basic parts of the electronic control diesel engine management system. In this work, in order to shorten the process of cylinder recognition, a quick and reliable method to determine the precise phase of diesel engine by possibly reducing the crank and cam speed signal is studied. Firstly, according to the firing order of the target diesel engine, speed signal, and the phase of the electronic control system have been designed, using two sets of speed computing devices of cam and crank, not only can shorten the time of cylinder recognition, but also can help to improve the reliability of the control system. And then two methods are proposed in this work, one is judge mode of counting teeth, the other is judge mode of checking window. By analyzing the working principles of the two modes, judge mode of checking window needs less cam and crank signal to cylinder recognition. In the judge mode of counting teeth, at least two cam signals are necessary for cylinder recognition and in the worst case, the cylinder recognition will not succeed until the engine spins two revolutions. While in the judge mode of checking window, the most rapid cylinder recognition only takes 70° crank angle and in the worst situation, the engine only needs to rotate around a little more than that cylinder recognition can succeed. Based on the finite state machine, drive control software of complex driver layer was developed for cylinder recognition control of window observation. Finally, the engine starting test has been done on the engine test bench in order to verify the feasibility of cylinder recognition strategy. By using the cylinder recognition of checking window, the fastest detected two cam teeth can achieve cylinder recognition success in the ideal condition and the cylinder recognition time is 0.3s, in the worse condition the successful cylinder recognition takes 1.3 turn and the time is 0.5s. Besides the starting success rate and time is statistic and compared between the above two modes, by using cylinder recognition of checking window, the success rate of starting has been increased by more than 10%, reaching 100%, and the starting time has been shortened from 1.5s to within 1s. Above experimental results show that the strategy is effective and feasible. The achievement of this strategy not only improves the preferment of electronic control diesel engine in starting condition but also perfects the timing control of electronic control system.