【作者】 陈宁；

【导师】 吴根茂； 魏建华；

【作者基本信息】 浙江大学 ， 机械电子工程， 2003， 博士

【摘要】 随着生产力的迅速发展和现代化程度的日益提高,能源的消耗量也急剧增加,导致全球性的能源危机和能源价格上涨,使得节能成为当今世界面临的重大技术课题之一。 液体粘性传动(HVD)是一种利用摩擦副之间的油膜剪切力来传递动力的新型传动形式,在大功率风机、水泵调速节能方面有着广泛的应用前景。作为流体传动领域中一门崭新的学科,本文从油膜润滑传动机理、系统动态特性、摩擦副的变形失效、在实际工况下开环稳态工作性能等几个方面对HVD技术进行了深入的研究,得到以下研究成果: 在对HVD技术的基础——油膜润滑传动机理——进行的研究中,首次采用独特的“边界条件分部叠加法”,推导出带径向油槽摩擦片间油膜压力分布规律和油液径向流量的实用解析解,进而求得动态油膜承载力计算公式。此为本学位论文创新点之一。 通过对HVD系统的动态特性的研究,建立了HVD装置的系统动态平衡方程,推导得到了HVD系统状态方程、HVD装置输出转速传递函数和输出扭矩传递函数,通过试验验证,最终得到结论:理论上,HVD系统对于输出转速和输出扭据来说总是开环稳定的。这为HVD装置在工程实际中的开环应用提供了理论依据。此为本学位论文创新点之二。 通过HVD装置摩擦副的变形失效现象的研究,建立了摩擦副热传导模型,数值计算得到了对偶片沿径向瞬时温度场分布和因此产生的周向热应力、径向热应力分布曲线,分析得到导致对偶片发生翘曲变形的原因是周向热应力而非径向热应力,因此变形的形式应该为碟形翘曲,并通过大量试验,总结出摩擦副参数的优化对提高其抗热变形能力的影响规律。此为本学位论文创新点之三。 论文还分析了电液控制系统和润滑油性能对实际HVD装置开环稳态工作性能的影响,设计了一种新型HVD专用转速调节阀,指出了HVD装置选用润滑油应具有的粘度范围和粘度指数要求,并在目前没有HVD专用润滑油的情况下,通过试验找到了最佳替代品,为HVD装置在工程实际中的开环应用提供了经验性数据。 本文研究工作进一步发展了HVD技术的基本理论,解决了HVD装置研制过程中的实际问题。根据本文研究成果研制成功的HVD装置分别在热电厂和自来水厂现场使用一年多,性能完全满足工程实际的需要,并获得了显著的经济效益。整个研究工作对HVD产品性能的提高和发展具有重要的理论和实践指导意义。更多还原

【Abstract】 As the result of the rapidly improving productivity and increasing modernization, energy consumption has been dramatically increasing in the past a few decades, which has led to the steady rise in energy price and a worldwide energy crisis. Nowadays, energy conservation has become one of the major areas of research.Hydroviscous drive (HVD) is a new type of power transmission mechanism, which utilizes the shear of oil film between two sets of discs for power transmission. As a brand new subject in the field of Fluid Power Transmission and Control, HVD has tremendous potentials in a wide range of applications such as speed regulation and energy conservation in large fans and pumps. This dissertation explores the fundamentals of HVD using a range of theoretical and experimental studies. The main contribution of this dissertation can be summarized in the following aspects.First, we explore the fundamental theories of the mechanism of oil film drive, which is the basis of HVD. Specifically, we derive the practical analytic solutions to the pressure distribution of the oil film and the parameters of the oil flow in the viscous drive for typical frication disks with radial grooves, based on analyzing the oil film between two sets of smooth discs. We also obtain the close-form solution to the load carrying capacity of the oil film. In our analysis we use a unique superposition-by-steps method of boundary conditions, which is based on the dynamical lubrication theory of the sector-thrust-step bearing. AH the theoretical solutions by experiments are validated by experiments.Second, we study the dynamics of HVD. In particular, we derive the dynamic balance conditions of the oil film among several disc couples, establish the dynamic balance equations of the HVD system, and give the speed output transmission function and the torque output transmission function. All the conclusions above are also validated by experiments. Our analysis leads to the crucial conclusion that the open-loop HVD system is always stable with respect to the speed output and to the torque output. This provides the theoretical foundation for applying HVD in real life engineering situations.Third, we investigate the distortion of the friction discs in HVD devices. Specifically, we build the model of the thermodynamics and heat conduction, based on which we use numerical computations to derive the thermal loading distribution on the friction discs of a hydro-viscous drive, and to plot the curves of the instantaneous asymmetric temperature field along the radial direction of the discs as well as the instantaneous asymmetric thermal stress field. Our analysis unveils the main cause of the distortion of the discs and suggests methods for effectivelypreventing the distortion phenomena.Finally, we investigate the performance of the steady state open loop of HVD in real life applications. In particular, we analyze the effects of electro-hydraulic systems and lubricants on the performance of the steady state open loop of HVD and present our design of a new special-purpose, speed-regulating valve for HVD. We also give the ranges of the acceptable viscosity and viscosity- temperature coefficient of the lubricants to be used in a HVD and identify by experimentation the best substitute lubricant available in lack of special-purpose lubricants for HVD.To summarize, in this dissertation we further the fundamental theories of HVD and provide solutions to a range of problems that have arisen in the development of HVD devices. HVD devices developed based on the results reported in this dissertation have been used by a heating power plant and a waterworks for more than 15 months and have shown satisfactory performance and have yielded significant economic benefits. The research results presented in this dissertation are significant in both practice and theory for the improvement of the performance of HVD products.更多还原