【作者】 陈林林；

【导师】 魏民祥；

【作者基本信息】 南京航空航天大学 ， 车辆工程， 2009， 博士

【摘要】 汽油的闪点低,挥发性高,易着火,给运输和使用造成许多不便。由于一些军事背景的特种车辆需要采用具有低挥发性的单一燃料覆盖所有的车辆和设备,提高安全性,减小后勤供应压力,尽量使多种燃料的不同设备的数量减至最低,当今世界上某些以活塞式汽油发动机为动力装置的特种车辆,部分已经使用以煤油为燃料的替代燃料。然而与国外同类技术相比,国内煤油发动机技术还比较落后,自主研发煤油发动机、逐步实现国产化,具有重要的研究价值和意义。本文根据某国防预研项目要求,主要进行了原型机试验数据的获取、煤油发动机工作循环数值模拟的研究、喷油控制模型及喷油控制策略的研究,以及燃油喷射电控系统及喷油标定系统的研制等,主要完成的工作和创新如下:(1)为了获取发动机数值建模、平均值建模和模型验证所需要的主要试验数据,基于LabVIEW软件平台开发了发动机数据采集系统,进行了台架测试试验,获取了发动机缸压等重要实验数据,并对原型发动机的平均机械损失压力进行了计算;(2)建立了煤油发动机工作循环数值模型,利用GT-Power软件进行了数值仿真计算;通过改变模型中的压缩比、空燃比、点火提前角、进气压力、进气温度等主要工作参数对发动机进行数值计算,分析主要结构参数和调整参数对煤油发动机性能及爆震特性的影响,研究煤油发动机性能参数的变化规律,为煤油发动机的参数优化匹配打下理论基础;根据各工况的标定策略,利用数值计算模型计算出煤油发动机不同工况的空燃比和初始喷油MAP图,减少了空燃比及喷油MAP图标定的工作量,缩短了研制电控喷油系统的时间,大大提高了工作效率;(3)采用机理建模和试验建模相结合的方法建立了二冲程煤油发动机平均值模型,进一步建立了煤油二冲程发动机喷油控制模型,提出了瞬态工况采用油膜补偿控制策略,便于对稳态工况和瞬态工况的喷油进行精确控制;建立了线性变参数状态空间模型以及稳态工况和瞬态工况的喷油脉宽控制模型,对稳态工况和瞬态工况喷油控制进行了仿真验证。仿真结果表明,基于线性变参数状态空间模型的喷油控制策略能够满足控制精度的需要,为煤油发动机控制系统的设计提供了理论依据;(4)为了实现对煤油发动机的精确喷油控制,基于Freescale 16位嵌入式芯片研制了具有一定抗电磁干扰能力、自保护能力、稳定可靠的煤油发动机喷油电控单元,包括硬件设计和控制软件的研发;为了实时监控喷油电控单元的内部数据信息,基于Visual C++6.0平台开发了上位机监控软件和发动机标定软件,实现在线读取、显示、修改喷油电控单元中的MAP图以及MAP图的保存和离线分析等功能;(5)完成了发动机喷油控制及标定半物理仿真试验。仿真试验表明,所研究的喷油电控单元性能满足控制要求,电控单元的抗干扰能力较强,能在一定的干扰环境下正常可靠工作,喷油标定系统功能强大、工作可靠;(6)完成了原型机喷油电控单元发动机台架试验。试验表明,喷油电控单元能够满足发动机起动工况、怠速工况、急加减速工况和稳定工况等各种控制要求,所研制的喷油电控单元运行良好,电控单元软、硬件稳定可靠,抗干扰能力较强;对升级后的煤油发动机喷油电控单元进行了实车台架试验。试验表明,利用数值优化计算出的煤油初始MAP图数据能满足发动机稳定运行要求;基于喷油模型的控制策略能满足煤油发动机的稳态及瞬态工况的控制要求,控制效果良好;同时台架试验结果表明,替换煤油燃料后,由于混合气热值减小、雾化效果变差等原因,煤油发动机动力性有所下降。更多还原

【Abstract】 Due to the low viscosity, low flash point, high volatility and easily firing, the inconvenience of gasoline appears in its transportation and usage. With the martial background, more and more vehicles and instruments are required for low volatile fuel as a single source in order to improve the safety, reduce the pressure of logistics support and minimize the number of instruments which use more than one kind of fuel. Nowadays, some gasoline engines installed on special vehicles partially use kerosene as a substitute fuel. Compared with the high technology in foreign countries, the Chinese kerosene engine technology gets behind in the international competition. So it needs far more researches and studies to apply the kerosene engines on vehicles, to keep engine running smoothly and gradually make the engine by ourselves in China.According to the requirements of some national deference pre-research project, the paper mainly included the data procurement from prototype engine, the simulation of kerosene engine working cycle numerical model, the research of modeling and controlling of fuel-injection system and the design of fuel-injection control system and fuel calibration system. And the mainly accomplished work and innovations are as follows:(1) In order to get the important testing data needed by the validation of engine numeric model and the mean value model, the engine data-acquisition system was built up based on the LabVIEW. Through the engine bench-test, many key data such as the pressure data within the combustion chamber were obtained. And then the mean mechanical-loss pressure of the prototype engine was figured out.(2) The numeric model of kerosene engine was built in the paper. The numeric simulation calculation was done based on the GT-Power Software. Through changing the compression ratio, air-fuel ratio, advance angle of ignition, intake pressure and temperature, a series of numeric simulations were accomplished. The paper analyzed the kerosene engine performances and knock characteristics in the different configurations and parameters. The variable law of the performance of kerosene engine was studied and theoretical basis for the kerosene was proposed in the parameters optimizing match.Due to the calibration strategy within the different working situations, the numeric simulation was applied, the air-fuel ratios within the different working situations were got and the kerosene engine initial fuel-injection MAP was figured out. So the period of the design of electric fuel-injection controller was reduced and thereby the work efficiency was highly improved.(3) Based on the mechanism modeling and testing modeling methods, the mean value model of two-stroke kerosene engine was suggested. Meanwhile the fuel-injection control model of two-stroke kerosene engine was also built up. In order to accurately control of the fuel-injection in both the stable state and transient state, the oil membrane compensation control strategy was introduced. In the paper, the linear variable parameter state-space model and the fuel-injection impulse width model in both the stable state and transient state were proposed. And the simulation validation was applied on the control of fuel injection in these states. The simulation results show that the fuel-injection control based on the linear variable parameter state-space model is able to meet the accurate controlling requirements, so the strong theoretical basis is supplied in the design of kerosene engine control system.(4) In order to achieve the accurate fuel injection in kerosene engine, the kerosene engine fuel-injection controller was designed based on the Freescale 16 embed microcontroller including the design of hardware circuit and control software. The designed controller has many advantages such as the ability of anti-electromagnetic interference, self-protection and running stably. In order to monitor the controller data in-time, the computer monitor software and engine calibration software were designed based on the Visual C++6.0. This software could read, display and amend the data of fuel-injection in the MAP and also save the data and analyze after tests.(5) The engine half-physical simulation test was accomplished. The simulation results show that the designed fuel-injection electric control unit can cover the requirements of engine performance. The electric control unit has high ability to resist the electromagnetic interference. Also the electric control unit is able to work stably in certain electromagnetic interference environment. And the fuel-injection calibration system also has strong functions and works stably.(6) The prototype fuel-injection electric control unit was tested on the engine testing board. And the test shows that this electric control unit could satisfy many work states such as start, idle, rapid speed up and stable working conditions. The designed electric control unit could work stably and the hardware and software of electric control unit are also well performed with high ability of anti-electromagnetic interference.The updated fuel-injection electric control unit was tested on the real engine testing board. And the testing results shows that the initial kerosene MAP from numeric optimizing calculation could be well performed in the stable-state running of the kerosene engine. The control strategy of fuel-injection model could satisfy the engine testing controlling requirements in both the stable state and transient state with good control performance.Meanwhile, the testing results shows that when the kerosene was applied in the test the performance of power was declined a bit due to the heat value of the mixture decreases, the atomization effects of the fuel become worse, and so on.更多还原