主动磁悬浮轴承系统中自消除间隙保护轴承的研究

发布时间：2018-01-20 04:28

本文关键词： 主动磁悬浮轴承自消除间隙保护轴承保护间隙支座转子跌落　出处：《南京航空航天大学》2015年博士论文　论文类型：学位论文

【摘要】：作为磁悬浮轴承系统中必不可少的组件之一的保护轴承,是磁悬浮轴承失效或过载后保护转子与定子系统免受损坏的重要屏障。传统保护轴承在转子跌落后,转子会产生剧烈振动,甚至产生涡动,巨大的碰撞力以及涡动离心力使得滚动轴承很容易损坏。针对传统保护轴承的不足,本文提出了一种可以在转子跌落后自动消除磁悬浮轴承系统中间隙的保护轴承,介绍了自消除间隙保护轴承的结构及工作原理,并进行了一系列相关研究。首先,建立了转子有限元模型,计算了转子两端未安装滚动轴承、一端安装滚动轴承和两端安装滚动轴承时转子的一阶、二阶弯曲模态频率与振型,并进行了相关试验研究。研究结果表明:在有限元法计算转子模态频率的过程中可以将滚动轴承等效为刚性圆盘;滚动轴承直接安装到转子上会降低转子的固有频率。其次,对自消除间隙保护轴承的运动学进行研究,分析不同的结构参数对支座的摆动角度大小的影响,并进行了试验验证。研究结果表明:连杆位于转动副1外侧的机构相对于连杆位于转动副1内侧的机构,支座能获得更大的摆动角度;在符合结构尺寸要求以及其他影响因素的条件下,可通过减小转动副1到转动副2的距离和转动副1到机构中心的距离、适当增加转动副2中的间隙来达到支座消除间隙所需要的摆动角度大小。然后,对间隙消除后支座与滚动轴承系统进行静力学分析,分析结果表明:支座间隙消除后,支座与外圈接触点处的法向力臂大小满足一定的条件时,支座才能够稳定支承滚动轴承外圈;并且分析了支座不同的端面形状对消除间隙时的摆动角度与法向力臂大小的影响,根据研究结果提出合理的支座端面形状。最后,对转子跌落到自消除间隙保护轴承上的动力学响应进行了详细地研究,分别建立了磁悬浮轴承失效前、后转子的动力学模型、磁悬浮轴承支承模型、滚动轴承受力模型、外圈—支座碰撞模型、单个支座振动模型以及支座摆动模型;仿真计算了不同参数对磁悬浮轴承失效后各部分动力学响应的影响,并在一个五自由度磁悬浮轴承试验台上进行相关跌落试验研究。研究结果表明:当选取合适的结构参数时,在转子组件跌落后,自消除间隙保护轴承基本上都能够在0.03 s左右消除滚动轴承外圈与支座之间的间隙,并稳定支承转子继续旋转;在间隙完全消除之前,滚动轴承会受到几次较大的碰撞,一旦间隙消除后,滚动轴承则只受到转子的离心力和重力作用,但此时滚动轴承外圈与支座之间则存在较大的弹性变形力;由于自消除间隙保护轴承消除间隙后滚动轴承外圈受到支座较大的挤压力作用,所以实际情况下应采用中、重系列的滚动轴承,而支座则需要根据具体转速下的接触应力大小选取相应的调质钢或渗碳钢等进行表面强化处理的材料;为保证自消除间隙保护轴承能够成功工作,支座端面形状应使支座消除间隙时与滚动轴承外圈碰撞处的法向力臂尽量小;滚动轴承润滑情况、滚动轴承外圈与支座之间的摩擦系数、转动副的摩擦系数,也对自消除间隙保护轴承能否成功工作起到至关重要的作用;转子较大的不平衡量会使得转子组件跌落后滚动轴承受到的碰撞力显著增加;支座数量的减少对滚动轴承受到的最大碰撞力无明显影响,但会增加滚动轴承外圈与支座之间的弹性变形力,并且支座的数量太少可能会导致转子的运动轨迹达到转子与磁悬浮轴承之间的间隙;自消除间隙保护轴承的安装角度基本上不会对机构的性能产生影响;与传统保护轴承相比,自消除间隙保护轴承能够有效减小转子组件跌落时滚动轴承受到的最大碰撞力,相对减小比率最高可达70%,并且消除了转子跌落到传统保护轴承后发生涡动的可能,显著改善了滚动轴承的工况,从而一定程度上延长了磁悬浮轴承系统中保护轴承的寿命,提高了磁悬浮轴承的可靠性。
[Abstract]:One of the essential components for protection bearing magnetic bearing system, is the magnetic bearing failure or an important barrier to the rotor and the stator system from damage overload protection. The traditional protection in bearing rotor drop, the rotor will produce severe vibration, and even produce eddy, huge impact force and the centrifugal force of the rolling bearing eddy easily aiming at the deficiency of traditional protection. The damage of the bearing, this paper proposes a protection can automatically eliminate the bearing clearance of magnetic bearing system in rotor drop, introduces the structure and working principle of self elimination bearing clearance protection, and conducted a series of related research. First, a finite element model of the rotor, the rotor is not installed at both ends the rolling bearing is calculated, one order is installed on one end of the rolling bearing and rolling bearing is installed at both ends of the rotor, the two order bending vibration frequency and vibration mode, and The related experimental research. The results show that: in the process of the finite element method to calculate the modal frequency of the rotor can be equivalent to a rigid disc rolling bearing; rolling bearings mounted directly to the rotor will reduce the natural frequency of the rotor. Secondly, to eliminate the gap protection of bearing movement were studied, analysis of the influence of different structure parameters of swing angle on the support size, and verified by experiments. The results show that: 1 the rotation mechanism is located side lateral link relative to institutions located in the joint 1 inner side of the connecting rod, bearing can obtain larger swing angle; in conditions conforming to the structure size and other requirements under the influence, can reduce the rotating pair 1 2 rotation pair distance and rotation distance 1 to center, increasing clearance revolute 2 to eliminate the bearing swing angle of the required size gap. Then, on After the elimination of clearance bearing static analysis and rolling bearing system, analysis results show that the bearing clearance is eliminated, and the bearing outer ring at the contact point of the normal arm size meet certain conditions, can support stable bearing rolling bearing outer ring; and analyzes the bearing different end shape to eliminate the gap when the swing angle and method to the effect of arm size, shape of the end surface of the supporting seat reasonably according to the research results. Finally, the rotor drop to the self elimination kinetics of gap protection on the bearing response were studied in detail, respectively for magnetic bearing failure, dynamic model of the rotor, magnetic bearing model, rolling bearing force model, the outer ring - bearing collision model, single bearing vibration model and the model simulation of the swing bearing; the different parameters of the magnetic bearing failure after each part of power Effect of response, and the related study falls into a five DOF magnetic bearing test rig. The results show that when selecting appropriate structure parameters, the rotor assembly after falling down from eliminating the gap protection of bearings can basically eliminate the gap between the rolling bearing outer ring and bearing at about 0.03 s. Stable and supporting the rotor continues to rotate; before the gap completely eliminated, rolling bearing will be several times larger impact, once the gap is eliminated, the rolling bearing only by rotor centrifugal force and gravity, but at the moment there is rolling large elastic deformation force between the bearing outer ring and bearing; since the elimination of the gap protection to eliminate bearing the outer ring of the rolling bearing clearance after the support pressure is larger, so the actual situation should be used in rolling bearing series, and support the need according to the specific speed The contact stress of the corresponding size of steel or steel surface hardening materials; to ensure the self protection of bearings can successfully eliminate the gap, bearing end shape should be to eliminate the gap with the bearing outer ring of the rolling bearing impact the normal force as small as possible; rolling bearing lubrication, the rolling friction coefficient between the bearing outer ring and bearing, rotating friction coefficients, to eliminate the gap from the success of work bearing protection plays a crucial role; the rotor unbalance will greatly impact force bearing makes the rotor assembly drop after rolling bearing significantly increased; the reduction of the number of maximum collision force of rolling bearing no obvious effect, but will increase between the rolling bearing outer ring and bearing force of elastic deformation, and bearing the number is too small may cause the rotor trajectory of the rotor and the The gap between the magnetic bearings; self eliminating installation angle gap protection bearing basically on the organization's performance is not affected; compared with the traditional bearing protection, self protection can eliminate the gap bearing the maximum impact stress of rolling bearing components reduce the rotor drop, the relative reduction ratio of up to 70%, and eliminate the occurrence of eddy may fall into the traditional rotor bearing protection, can significantly improve the rolling bearing condition, to a certain extent extended bearing protection magnetic bearing system in life, improve the reliability of the magnetic bearing.

【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH133.3

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