【作者】 王睿君；

【导师】 邵雪明； 陈丽华；

【作者基本信息】 浙江大学 ， 流体力学， 2010， 硕士

【摘要】 作为液压系统的控制元件,节流阀的作用是通过改变节流口的过流面积来控制液压油流量,从而控制整个液压系统的全部功能。因此节流阀性能的可靠性,对整个液压系统是否能正常工作起到非常重要的作用。但在某些工作条件下,节流阀会发生热卡紧/热卡死失效故障,使阀套和阀芯之间的配合摩擦阻力增加,相对运动动作迟滞,节流阀控制精度严重降低,液压系统无法正常工作。本文以V型节流阀为研究对象,基于CFD和FEM相结合的流固耦合数值模拟方法对这一现象进行了深入研究。本文首先通过数值模拟对节流阀热卡紧/热卡死现象的产生机理进行了合理的分析：即当粘性较大的液压油流入节流阀阀口时,由于槽口的节流作用液压油在节流槽内形成高速剪切流,因而粘性加热效应非常显著,节流槽口附近局部温度迅速升高,导致阀芯和阀套上槽口附近的区域在较短时间里受热膨胀变形,阀芯和阀套之间的配合间隙减小,从而出现热卡紧故障；当径向变形量进一步增大到大于阀芯和阀套的设计间隙时,则会发生阀芯热卡死现象。然后,本文通过数值模拟系统地分析了液压油流动方向、节流槽结构参数和工作压差等因素对粘性加热导致节流阀热变形的影响规律,发现液压油流动方向和结构参数是影响节流阀阀芯热变形规律的主要因素；工作压力的增加使结构参数对节流阀热变形特性的影响放大。节流槽口温度峰值和径向变形极值在流入工况下随节流阀开度增大呈现先增大后减小的变化趋势,在流出工况下基本呈现持续增大的趋势；节流阀质量流量增大到饱和状态的过程中,流入工况最大径向变形极值高于流出工况。在相同的质量流量下,节流槽口径向变形量随着工作压差增大而加大。最后,本文动态分析了节流阀初始开启过程中阀套和阀芯的热变形过程。上述研究结果为节流阀的优化设计,以避免节流阀热卡紧/热卡死失效故障提供了理论基础,具有实际工程意义。更多还原

【Abstract】 Throttle valve is used as control element to dominate hydraulic oil flux in fluid power transmission and control systems. The reliability of throttle valve is important to the system operation. However, throttle valve is source of high temperature in hydraulic system, and temperature increasing around notches due to viscous heating effect of hydraulically oil may cause valve heat stick or jam fault under some work conditions, which cause abnormal problems such as low efficiency, high energy and deadlock fault of sleeve and spool during operation. In this paper, this phenomenon was studied by numerical fluid-solid coupling method on throttle valve with V-notchesFirstly, this thesis explained generation mechanism by numerical simulation method: Heat deadlock fault of sleeve and spool happens to valve when radial deformation value exceeds the allowable radial clearance between the spool and valve sleeve, which because the viscous heating effect of the high speed and shear oil flow with large viscosity inside the valve is significantly, and then it causes serious thermal deformation of throttle valve around notches.Afterwards, this paper analyzed the influence of flow directions, structural parameters as well as work pressure drop on temperature and thermal deformation distribution: The thermal deformation distribution inside V-notches is closely related to oil flow direction and notch structural parameters. And the change of pressure drop also produces affects as the secondary influencing element. Finally, the process of thermal deformation during valve opening period was investigated. Thus these studies provided theoretical reference for designers.更多还原