【作者】 刘小平；

【导师】 姚春德；

【作者基本信息】 天津大学 ， 动力机械及工程， 2008， 博士

【摘要】 节约能源,控制有害排放,已成为内燃机技术发展的主导方向。传统气门驱动系统具有一定局限性,通常只能保证在某一工况优化发动机的性能,其凸轮型线在出厂时即已经固定,无法在运行过程中进行调节,它使得发动机的性能难以在各种工况下都达到优化。可变气门正时能够较好的满足发动机不同转速、负荷工况对于配气正时的不同要求,从而整体提高发动机综合性能,可变气门技术已成为衡量发动机性能的关键技术之一。本文在广泛参阅国内外研究及生产现状基础上,结合企业合作项目的实际情况,采用模型分析,仿真分析计算,设计制造,试验测试和整机试验相结合的研究模式,对可变凸轮轴配气相位器系统(VCT)进行了较为系统和深入的研究。主要研究工作可以概括如下:1.通过研究可变凸轮轴配气相位系统的工作机理,建立了可变凸轮轴配气相位系统的机、电、液、磁仿真模型,利用MATLAB\SIMULINK软件对系统进行仿真计算。揭示了相位器系统各结构参数及各种运行参数对其系统性能的影响规律,以便对相位器的设计制造提供可靠的参数和依据。2.通过对相位器液压部分的分析,研究了可变凸轮轴配气相位可能的泄漏情况,建立了系统泄漏的数学模型,对可能存在的内外泄漏进行计算,并对泄漏控制进行分析。通过对相位器系统的泄漏分析,揭示了系统各种间隙对其泄漏的影响,为相位器系统的设计制造提供可靠的参数和依据。3.在分析典型可变配气相位机构特点,剖析配气相位中影响发动机性能的各种可变因素的基础上,确定了基于凸轮轴调相的可变配气相位结构方案。通过仿真计算和借鉴国外的开发经验,设计了一套可变凸轮轴配气相位机构。分别从叶片、密封、锁止销和油道布置等方面对叶片式连续可变凸?轮相位器本体结构着重分析与选择,并阐述了进、排气相位器的不同设计考虑,明确了材料的选取原则。另外,对相位器的设计原则进行了详细阐述,指出设计相位器的要满足的技术关键。4.建立了可变配气相位器的试验测试系统,为可变相位器系统的深入研究及产品开发提供了有效的工具。针对液压油驱动VCT系统液力、机械结构具有非线性特征及系统时变性等特点提出了PID控制策略,研究表明,PID控制来说有较好的执行性能,提出的控制算法具有结构简单、实时性好、响应快等优点,较好的满足了VCT控制要求。并利用测试系统分析和探讨了相位器系统机构工作过程中参数的变化规律。测试系统采用电控,智能,集成的控制方式及友好的测试界面。5.对新研制的可变配气相位器在发动机上进行试验研究,完成对相位器本体系统进行最终的实机测试。结果显示,新研制得可变配气相位器可以满足发动机要求,表明为此研制的性能测试装置已经可以用于新开发的相位器性能检测。更多还原

【Abstract】 Energy conservation and the control of harmful emissions have become the dominant direction in the development of internal combustion engine technology. Conventionally, the valve timing and lift have been fixed in use, optimized for the standard condition and circumstances. The valve timing of engine can’t be permitted variation during engine operation. So this valve drive system has certain limitations, which make engine performance in various conditions difficult to optimize. However variable valve timing(VVT) can better meet the different engine speed, load conditions and thereby improve overall engine performance for the allocation of gas is different requirements. VVT has become one of the key technologies.This dissertation investigates it on the basis of a host of reference, and combines the real situation of the subject. A comprehensive study pattern, the integration of analysis, simulation, design and production, unit test and experimental engine is applied to develop variable cam timing(VCT) system. Major research work can be summed up as follows:1. Through analysis of the whole system, a VCT mathematical model is set up, including mechanical, electrical, hydraulic and electromagnetic simulation mode. The influences of different working parameters and structure parameters of VCT are discussed by using the MATLAB/SIMULINK code with strong capability of engineering calculation and the number analysis. The effect of the systemic operational parameters and various parameters of VCT on its operation process is revealed. It can provide reliable parameter and data to the mechanical design and manufacture.2. Through analysis of the hydraulic system, the leakage of vane-type VCT mathematical model is set up. We carry out the forecasts and verifications of the influences that the various factors exert on the leakage flow. According to the study on leakage, the effect of various parameters of VCT on its operation process is revealed. It can provide reliable parameter and data to the mechanical design and manufacture.3. This dissertation analyzes the practical technology for VVT and the variable factors of VVT. The technology for VCT based on the camshaft phase shift theory is determined. Based on the simulation results and learning from foreign experience, VCT is designed. Through analysis of vane-type VCT, the sort and design are introduced about the structure such as vane, seal, lock pin and oil passage, and it is revealed that the different designs of the structure of intake and exhaust cam and the select of material. Furthermore, the design and key technique of VCT are primarily described.4. The measuring system is developed for VCT. For the problem of hydraulic pressure serving as the driving source of the VCT and the mechanism of the VCT have non-linear characteristics, the policy of PID control is suggested.Study indicates that the control arithmetic is simple in structure,good in real time capability,fast in response and preferably satisfies control request.By the testing systems, theVCT characteristics and parameters related to operation process of VCT can be analyzed. Electronic control, intelligent, integrated control and testing friendly interface is applied to the measuring system. Testing system is domestic initiative.5. Experiment study of VCT on SI engine is done. At the same time, it plays a final measuring of successful design. The results show that the new VCT can meet the requirements of engine and the measuring system can be used for performance testing of VCT.更多还原