金属带式无级变速器电液数字技术研究

发布时间：2018-03-04 12:23

本文选题：无级变速器　切入点：电液控制　出处：《吉林大学》2011年硕士论文　论文类型：学位论文

【摘要】：当今时代,汽车已经与人们的生活密不可分,随着汽车的广泛普及和人们对汽车品质要求的逐步提高,汽车自动变速技术已成为汽车传动系统领域研究的重点。实现自动变速的方式有很多,但是目前众多的自动变速器中唯有无级变速器能够实现速比的连续变化,并且时刻都能保证发动机工作在最佳区域。金属带式无级变速器(Continuously Variable Transmission,简称CVT)是当今汽车变速器领域里的一种理想变速器,它的无级变速效应可实现发动机转速与车速的相对独立,保证发动机始终工作在理想转速区域。CVT的变速过程是靠电液控制系统实现的。早期CVT控制系统多采用伺服控制,电液伺服阀具有响应速度快、控制精度高等优点;但其同时也存在结构复杂、控制复杂、成本高、抗污染能力差等缺点。因此,后来逐步发展为电液比例控制。电液比例阀相对电液伺服阀,具有成本低,抗污染能力强等优点;但由于电液比例阀是以比例电磁铁作为电-机转换装置,故又存在滞环大的缺点,而且需要连续的模拟信号进行控制。目前新兴的数字式液压阀不但继承了伺服阀控制精度高、比例阀成本低的优点,而且还克服了伺服阀结构复杂、抗污染能力差的缺陷。另外,数字式液压阀控制方式简单,无需数模转换装置即可与计算机直接接口。随着电子技术的迅速发展,在CVT液压控制系统中采用数字式控制技术将会是一种发展趋势。本文正是从上述需求出发,根据CVT变速过程中夹紧力和速比的控制要求,设计了用于CVT夹紧力控制的数字溢流阀、速比控制的数字减压阀以及集成各插装阀的液压阀块。论文主要内容如下: (1)对各种自动变速器做了比较,重点介绍了金属带式无级变速器的工作原理,其核心电液控制系统的工作原理及发展历程。 (2)对电液比例技术和电液数字技术进行了分析,对现有CVT的电液控制系统进行了分析。 (3)根据CVT工作过程中从动缸和主动缸对压力和流量的需求确定了数字溢流阀和数字减压阀的设计要求和物理结构;通过静态特性计算确定了数字溢流阀和数字减压阀的尺寸参数,并加工出了数字溢流阀和数字减压阀的原型阀以及集成有数字溢流阀和数字减压阀插槽和油道的液压阀块。 (4)应用AMESim仿真软件搭建了数字溢流阀和数字减压阀的仿真模型,通过仿真分析了数字溢流阀和数字减压阀的关键参数对输出结果的影响,并对数字溢流阀的关键参数进行了优化。 (5)在液压系统试验台上对数字溢流阀和数字减压阀分别进行了试验,通过试验对数字溢流阀和数字减压阀的静、动态特性做了分析,并最终确定了数字溢流阀的压力-步位关系,数字减压阀的输出压力、输入压力以及先导级占空比三者间的关系。本文的主要创新之处在于设计了可用于CVT液压控制系统的数字溢流阀和数字减压阀。
[Abstract]:Nowadays, automobile is closely related to people's life. With the popularization of automobile and the improvement of the quality of automobile, Automotive automatic transmission technology has become the focus of research in the field of automotive transmission system. There are many ways to achieve automatic transmission, but at present, only CVT can realize the continuous change of speed ratio. And at all times to ensure that the engine works in the best area. Metal belt stepless Variable transmission (CVT) is an ideal transmission in the field of automobile transmission. Its stepless speed effect can realize the relative independence of engine speed and speed. It is ensured that the variable speed process of engine in the ideal speed range is realized by the electro-hydraulic control system. The early CVT control system mostly adopts servo control, the electro-hydraulic servo valve has the advantages of fast response speed and high control precision. However, it also has some disadvantages such as complex structure, complex control, high cost, poor anti-pollution ability and so on. Therefore, the electro-hydraulic proportional valve is gradually developed into electro-hydraulic proportional control, which has the advantages of low cost and strong anti-pollution ability compared with electro-hydraulic servo valve. However, the electro-hydraulic proportional valve uses proportional electromagnet as the electro-mechanical conversion device, so it has the shortcoming of large hysteresis and needs continuous analog signal to control it. At present, the new digital hydraulic valve not only inherits the high control precision of servo valve, The proportional valve has the advantages of low cost, and overcomes the disadvantages of complex structure and poor anti-pollution ability of servo valve. In addition, the control mode of digital hydraulic valve is simple, With the rapid development of electronic technology, it will be a development trend to adopt digital control technology in CVT hydraulic control system. According to the control requirements of clamping force and speed ratio in the process of CVT speed change, the digital relief valve for CVT clamping force control, the digital pressure reducing valve for speed ratio control and the hydraulic valve block integrated with each cartridge valve are designed in this paper. The main contents of the thesis are as follows:. This paper introduces the working principle of the metal belt stepless transmission, the working principle and the development course of the core electro-hydraulic control system. 2) the electro-hydraulic proportional technology and electro-hydraulic digital technology are analyzed, and the existing electro-hydraulic control system of CVT is analyzed. (3) according to the pressure and flow demand of driven cylinder and active cylinder in CVT process, the design requirements and physical structure of digital relief valve and digital pressure reducing valve are determined. The dimension parameters of digital relief valve and digital pressure reducing valve are determined by static characteristic calculation. The prototype valve of digital relief valve and digital pressure reducing valve and hydraulic valve block with digital relief valve and digital relief valve slot and oil channel are machined. The simulation models of digital relief valve and digital pressure reducing valve are built by using AMESim simulation software. The influence of key parameters of digital relief valve and digital pressure reducing valve on the output result is analyzed by simulation. The key parameters of digital relief valve are optimized. The digital relief valve and the digital pressure reducing valve are tested on the hydraulic system test bed respectively. The static and dynamic characteristics of the digital relief valve and the digital pressure reducing valve are analyzed through the test. Finally, the pressure-step relationship of the digital relief valve and the output pressure of the digital relief valve are determined. The main innovation of this paper lies in the design of digital relief valve and digital pressure reducing valve which can be used in CVT hydraulic control system.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH137.52

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