【作者】 李克；

【导师】 苏万华；

【作者基本信息】 天津大学 ， 动力机械及工程， 2010， 博士

【摘要】 随着排放法规的日益严峻和共轨技术的广泛应用,以“均质压燃、低温燃烧”为基本特征的新一代内燃机燃烧技术也得到深入地研究和应用。电控技术是实施这些燃烧理论的有效途径,是新一代清洁、高效、智能化发动机技术的重要组成部分。本文回顾了柴油机电控技术的发展趋势以及电子设计自动化(EDA)技术的发展特征,并且针对共轨技术和新一代燃烧技术的特点及控制要求,采用全新的电子技术完成了一种全新构架发动机控制单元(ECU)的开发,并以研制成功的ECU为核心对新开发的共轨燃油喷射系统进行了实验优化研究。新一代燃烧技术要求燃油喷射控制系统具备可灵活调制燃油喷射模式、精确控制喷油定时和油量等参量,这使得控制系统中涉及到大量数字逻辑电路的开发。为此,本文以MCF5233微处理器和CPLD(复杂可编程逻辑器件)为核心构架进行了ECU的开发和研制,该构架可以实现时间任务、算法任务和数字逻辑任务的平行处理。为了提高喷油器电磁阀的响应速率,基于CPLD创新性地提出了斩波数字调制式升压模块,其替代了传统升压模块中的PWM(脉宽调制)专用IC和斜波补偿电路等,简化了升压模块的结构;同时,基于CPLD完成了对喷油器高、低压驱动信号的逻辑合成,实现了对喷油器的高、低压分时控制。相对于本课题组上一代天然气ECU(专利号:02125326.9),该ECU更适合新一代燃烧技术和共轨技术发展的需要。本文基于MCF5233-eTPU模块,利用转速信号进行了瞬时转速(角速度)算法设计,借助于瞬时计算的角速度提高了压力控制阀(PCV)和喷油器控制的精度,改进了系统时序控制的灵活度。其中基于内外参考点法,解决了系统时序控制的稳定性,进一步提高了定时精度。利用结构体数组对喷射参数进行定义,仅一次中断服务,即可实现了多次喷射控制,提高了CPU的工作效率,借助eTPU的qom功能满足了燃油控制系统不同喷射模式灵活调制和自由切换的要求。另外,依据可靠性设计理论,对ECU进行了全方位的可靠性设计,开发了部分故障诊断单元,加强了ECU系统的可靠性。本文从软件工程学角度,基于嵌入式实时系统的生存周期模型,采用面向对象技术和实时系统并行设计方法(CODARTS)对ECU系统进行了软件开发,在确保ECU系统实时性的同时兼顾其可移植性和扩展性。提出以COBRA的对象标准进行系统的面向对象需求分析,使面向对象技术和CODARTS方法具有很好的兼容性。同时,为了满足燃油喷射系统开发的需要,构建了人机交互平台。以法国EFS电控燃油喷射系统测试平台为基础,以自行研发的ECU为核心,搭建了用于共轨电控燃油系统标定的实验平台。在此平台上对ECU各功能模块进行了验证,对升压模块和喷油器驱动电路进行了优化研究。鉴于升压电路结构参数多,以及ECU对升压电压的恢复响应要求高等特征,基于Pspice仿真软件对升压电路的结构参数进行了优化。结果显示,该升压模块的最大转换效率可以到达90%以上,ECU的实验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,满足整机运行范围内ECU的需求。针对喷油器驱动通道存在的不一致性问题,通过实验重点研究了上电回路和放电回路对喷油器特性的影响,根据实验分析结果,采用在各回路引入定值电阻的方案,弱化了各驱动通道阻抗的不一致性,该方案提高了喷油器驱动通道的一致性,中等油量(40mg～50mg)时各驱动通道的RSD(相对标准偏差)由优化前的11.9%降低到优化后的3.8%。最后通过实验利用ECU对新开发的共轨燃油喷射系统进行特性研究,利用调试通过的电控燃油系统对珀金斯135Ti柴油机进行了改装。实践证明该ECU到达预期目标,具有很好的应用前景。更多还原

【Abstract】 With the increasingly stringent emissions regulations and common-rail technology widely used, ?Homogeneous, Compression ignition, Low-temperature combustion?, as the basic characteristics of a new generation of combustion technology, has also been in-depth studied and applied. Electronic control technology is an effective way to implementation of combustion theory, and is an important component of new generation of clean, efficient and intelligent engine technology. This paper reviews the development trends of diesel engine electronic control technology and electronic design automation (EDA) technology features. Aiming at characters and control demands of HPCR (High Pressure Common-rail) technique and new generation combustion technique, ECU?s (Engine Control Unit) development is completed by adopting bran-new Electronic technology, and lastly optimizing experiment research on newly developed HPCR fuel injection system is carried out with the successfully developed ECU.A new generation of combustion theory demands fuel injection control system with flexible fuel injection modulation model, precise control of injection timing and oil quality and other parameters, which makes control systems in the development of a large number of digital logic circuits. Therefore, with 32-bit microprocessor MCF5233 and CPLD (Complex Programmable Logic Device) as the core framework, the ECU is designed, which can achieve time tasks, algorithm tasks, and digital logic tasks to concurrently process. For improving response speed-rate of injector electromagnetism valve, an innovative type of digital modulation booster module, based on CPLD, is brought forward, which substitutes IC of making PWM (Pulse Width Modulation) signal and the circuits of compensating inclined-wave in traditional booster module, and predigested structure of the module. At the same time, based on CPLD the logic synthesis of injector, drive signals of high-low voltage are completed, which realize high-low voltage time-sharing control to injectors. Relative to the older generation natural gas ECU (Patent Number: 02125326.9), the ECU is more suitable for next-generation combustion technology and common-rail technology development?s needs.Based on MCF5233-eTPU module, the instantaneous speed algorithm is designed by using crank-speed signal, thinks to which design of timing control for PCV (Pressure Control Valve) and injector is developed, and flexible timing control can be achieved. The internal and external reference point method was developed , which solves the stability of the system timing control, and further improves the timing accuracy. Injection parameters is defined by using an structure array, and using only one interrupt service, multistage injection control is achieved to improve the working efficiency of the CPU. With the help of eTPU-qom function, fuel control system meets these requirements of flexibly modulating of injection mode, and freely switching between different modes. In addition, based on reliability design theory, the all-round reliability design for the ECU is completed, and some of the fault diagnosis units are designed, which further strengthen reliability of ECU.From software engineering point of view in this paper, the life cycle model of embedded real-time system is built. Using object-oriented technology and CODARTS (Concurrent Design Approach for Real-Time System), the ECU system software is developed to ensure ECU systems to be real-time and transplantable and expansible at the same time. For making object-oriented technology and CODARTS to be better compatible, a method is brought forward, which makes the object standard of COBRA (Concurrent Object Based Real-time Analysis) to be carried through the whole process of object-oriented requirement analysis of software system. Meanwhile, in order to meet the fuel injection system development?s needs, a platform for human-computer interaction is built.Based on electronically controlled fuel injection system bench from FRANCE EFS INC, with self-developed ECU as the core, an experimental calibration platform for common-rail electronically controlled fuel system is set up. On this platform, all functions of ECU are verified while booster module and driver circuit of injector is optimized. In view of excessive configuration parameters in booster circuit, and higher request of ECU for boost-voltage characteristics of the recovery response, based on Pspice circuit simulation software, the structural parameters of the booster module is optimized. The results shows that the biggest booster module conversion efficiency can reach more than 90%, and the ECU’s experiments showed that the biggest boost-voltage fluctuation don?t exceed 10%, and the renewing-time only was 1.3ms, which met these needs of ECU within engine operating range.Aiming at the question about inconsistencies of injector drive channels, effect of power circuit and discharge circuit on injection character is researched as a focus of experiment. According to the analysis of the experimental results, the introduction of a fixed value resistance into each loop, weakening the various driven channel impedance inconsistencies, improves the consistency of injector drive channels, which results in the driver channel RSD (relative standard deviation) down to 3.8%, from 11.9% before optimization in jet fuel of 40mg~50mg. In the end, research on character of newly developed common-rail fuel injection system is completed by using ECU in practical experiment, and the 135Ti diesel is modified by using the new electronic control fuel system that has passed all tests. Practice has proved that ECU developed in this work reached anticipated target and had good application prospects.更多还原