基于轴向支撑超声波悬浮高速电机的研究

设计了一种轴向支承电机转子的超声波悬浮支撑结构。采用圆锥型轴承超声悬浮支撑结构,并对承载能力进行了分析和测试,获得了悬浮力与悬浮间隙间的关系,在振动过程中形成稳定的承载气膜;从理论上分析了在超声悬浮支承条件下,悬浮间隙变化对于电机转子临界转速与振动模态的影响情况,对转子最高转速与悬浮间隙的关系进行了实验研究。结果表明,通过减小悬浮间隙,能增强间隙气膜的刚度支承效果,并提高转子的最高转速。     

舰载雷达方位支承转动装置的分析

通过雷达方位支承转动装置方位主轴的受力分析,认为方位轴不铅垂的倾斜角γ主要来源于方位支承转动装置。对于采用滚动轴承的方位支承转动装置,轴承的转动精度和轴承的游隙是产生γ角的主要因素。因此合理选择和使用方位支承轴承的类型和方式对提高方位主轴的转动精度、减少雷达测角误差有重要意义。另外,对采用刚度较差的四点接触球轴承作为雷达方位转动装置的支承轴承,应采取必要的预紧措施。     

大型天线座方位支承转动装置结构设计

介绍了某大型天线座方位支承转动装置的结构设计方案。该设计方案中采用了能同时承受径向力、轴向力和倾覆力矩的特大型钢丝滚道轴承。文中对钢丝滚道轴承的承载能力进行了校核，对主要结构件的刚度进行了分析计算。尤其是在钢丝滚道轴承的滚压磨合方法中提出的递增加载原则、载荷作用线与轴承旋转轴线重合原则和刚度原则。是工程设计和实践经验的总结。     

水下涡轮机转子系统非线性动力学特性研究

在考虑支承滚动轴承内部间隙、轴承非线性Hertz接触刚度及转子不平衡量的基础上,建立了水下涡轮机刚性水平转子系统的动力学模型;采用变步长的Rouge-Kutta-Felhberg法对系统动力学模型进行了数值解析,基于混沌与分岔理论分析了系统的非线性动力学特性.研究表明,随着轴承间隙的增大,系统混沌响应区变宽;随着转速的提高,系统在转子不平衡激励、轴承变柔度激励作用下,经周期、拟周期、混沌的振动变化过程.     

轴承预紧力对滚珠丝杠系统动态特性影响分析

为了解轴承预紧力对滚珠丝杠系统动态特性的影响,以某卧式磨床滚珠丝杠为研究对象,建立了丝杠的三维模型,并以弹性支承约束模拟角接触球轴承对丝杠的支承。在此基础上,利用ANSYS对磨床滚珠丝杠系统进行模态分析。通过修改不同预紧力下轴承的支撑刚度,得到了在不同预紧力下的系统各阶固有频率。分析结果表明,在不同的轴承预紧力下,滚珠丝杠系统的结构刚度会发生变化,使系统的固有频率改变,且随着预紧力增大而增大。磨削状态稳定时,磨削预应力对滚珠丝杠系统的影响较小。     

超高刚度自主式空气静压支承发展现状

本文介绍了提高空气静压轴承刚度的方法及国外超高刚度自主式空气静压支承发展状况。     

雷达天线座传动系统转速波动影响因素分析

为了更深入研究齿轮、轴承系统动力学问题,特别是研究其结构和几何参数对其动力学性能的影响,文中结合实际应用需要,基于某机载雷达天线座传动系统,着重考虑齿轮啮合时的时变刚度、齿轮侧隙以及轴承支撑刚度、摩擦等因素,建立了齿轮、轴、轴承动力学模型,运用数值仿真方法,研究了上述因素对其转速波动的影响.根据上述参数改变对转速波动影响的分析可知,当结构参数调整到一定值时,对转速波动的影响就不再有很大的变化,趋于平稳,此时若再继续调整结构参数就会浪费空间尺寸及重量,尤其是重量和空间都较为苛刻的机载产品,这对齿轮、轴承系统优化设计提供一定的理论依据和方法.     

水轮机转子磁悬浮承重系统之电磁装置漏磁研究

面对传统推力轴承支承系统存在的问题,本着采用混合磁悬浮装置和传统推力轴承共同完成支撑的目的,研究了漏磁对电磁装置的影响。为此,引入了气隙比的概念,提出了通过改变气隙比的值来研究漏磁对系统悬浮力的影响,通过一系列仿真,得出了随着漏磁的增加,系统电磁悬浮力反而增大的结论。结合了陕西安康水电站水轮机组的数据,通过各方面的约束,在永磁装置确定的情况下,计算出了电磁装置较优的电气及结构参数。     

机载雷达驱动机构的刚度分析计算

天线驱动机构(又称天线座)作为雷达系统中的驱动单元,它的固有频率影响到天线座伺服带宽.以前对天线座固有频率的计算及分析很少考虑到驱动机构中运动副(轴承)对整个天线座刚度的影响,本文通过对某机载雷达天线座刚度的分析计算看到,轴承刚度对天线座固有频率产生的影响.     

专家系统、人工智能

0103286运行状态下转子-轴承系统模态参数辨识方法的研究[刊]/晏克俊//西安理工大学学报.—2000,16(2).—196～199(D)利用转子动平衡中,动平衡机可改变支承刚度的特点,提取改变支承刚度后转子滑动轴随系统的自由振动响应;用小波变换的方法剔除转子不平衡响应及高频干扰,给出了一种转子运行状态下分析与实验相结合识别模态参数的方法。模拟试验结果表明此方法的正确性和可行性。参6     

Improvement of dynamics for a superconducting magnetic bearing(SMB) system

This paper describes the improvement of dynamics for a passive-type superconducting magnetic bearing (SMB) system. The SMB system is composed of a pair of SMBs with high T_c (critical temperature) superconductors and a rotor with some permanent magnets. The rotor is passively supported by the SMBs without any control mechanisms. The superconductors of the SMBs were field-cooled in the experiments. After the superconductors were cooled, bearing housings of the SMBs were forced to change in the axial direction. Then, the stiffness change and damping coefficient change resulting from the housing displacements were investigated. From the experimental results, it is found that the static stiffness is related to the dynamic stiffness and that the stiffness and the coefficient change according to the housing displacements. The rotor displacement and the rotation angle near the resonance rotation speeds also change according to the housing displacements. These results show that the stiffness and the damping coefficient of the SMB system can be controlled using these processes     

Mechatronics design of stiffness enhancement of the feed supporting system for the square-kilometer array

Design and implementation of stiffness enhancement of a feed supporting system for the square-kilometer array (SKA) using electrorheological (ER) variable damper is presented in this paper. The feed supporting system consists of a large parallel cable manipulator and a fine-tuning Stewart platform. Hence, the feed supporting system is a large delay system and sensitive to the influence of wind. Furthermore, the adjustment of the fine-tuning Stewart platform will affect the coarse tracking control. Therefore, in order to suppress these disturbances and realize the independent control of the two parallel manipulators, it is necessary to enhance the stiffness of the feed supporting system. The proposed ER variable damper is designed and directly attached to the shaft of the servomotor of the feed supporting system to achieve high servo stiffness and trajectory tracking accuracy. The model of the feed supporting system is first derived, the structure of the variable-viscous ER damper is presented, and then the damping coefficient model is developed. The validation of this stiffness enhancement design of the feed supporting system is demonstrated with position PD control of the feed supporting system. This result has built a solid base for the accomplishment of the high-accuracy requirement of the SKA.     

一种高效压电旋转驱动器的设计和研究

为解决压电双晶片旋转驱动器能量利用效率低,转动力学性能差等问题,设计了一种高效压电旋转驱动器。驱动器以压电双晶片组为原动件,通过双离合器机构耦合,将双晶片组正、反两个方向产生的扭转运动全部转化为连续旋转输出,提高了能量利用效率。通过双晶片组对称结构的设计和安装,改善了驱动器力学性能和刚度。通过有限元仿真分析和实际测试,驱动器转速与驱动信号的频率电压基本成线性关系,驱动器承载能力明显提升。驱动器结构紧凑,体积小,普通正弦信号即可驱动,不需要特殊驱动信号或专门时序控制电路,运行稳定可靠,控制简单高效,适用于微驱动领域。     

一种转子位置传感器无刷直流电机速度检测方法

本文提出了一种利用转子位置传感器发出的信号测量无刷直流电机（BLDC）转速的方法,并设计了相应的转动方向测定电路和数字PI速度控制器模块。通过利用比例积分控制器计算半个转动周期内的两次连续测量值,结合提出的转动方向测定电路和数字PI速度控制器,可以得出具有双倍测量频率的转子转动周期的准确值。最后将提出的方法在FPGA平台进行了实现,并与真实数据的对比表明,该算法在无换向器直流电机上可以获得具有高精度及高频率的速度测量值（每转动1周至少测量6次）。     

空间相机用变形镜的支撑结构设计

变形镜支撑结构自身性能的优劣将直接影响变形镜的像差校正能力。给出一种空间相机用变形镜的结构,结合材料属性与加工工艺,分析了不同结构形式支撑底座的特点,发现采用碳纤维增强复合材料（CFRP）制作的实体式结构明显优于选用钛合金制作的筋板式结构,指出支撑底座材料的比刚度以及支撑底座与反射镜材料之间的线胀系数差别分别是影响变形镜自重变形和热变形的主要因素。比较了不同的支撑方案,发现采用背部三点支撑可以改善周边三点支撑时由重力因素导致的反射面边缘塌陷现象,在z向重力下面形RMS值由15.38 nm降至4.17 nm,降低了73%,且热变形更加均匀,4℃温升时的RMS值由3.68 nm降至3.22 nm,降低了12.5%,一阶频率也由1513 Hz提高至1982 Hz。这说明该变形镜结构的动、静态刚度及热稳定性均满足空间相机的应用要求。     

Vibration control of flexible rotor by inclination control magneticbearings with axial self-bearing motor

An inclination control method has been developed to stabilize a flexible rotor on magnetic bearings that operates over several critical bending speeds. It is desired to increase the rotating speed of the centrifuge which is supported by magnetic bearings on both ends of the rotor. Each magnetic bearing is composed of a pair of hybrid-type magnetic bearings and can control the inclination as well as the position of the rotor. The central position and the inclination of the rotor are calculated by the sum and difference of the measured displacements. These two quantities are supplied to the individual proportional and derivative controllers to obtain the actuating signals. The central position is controlled to provide sufficient stiffness to support the rotor while the inclination control capability is used to obtain adequate damping for the bending mode of the rotor. The control approach is tested on a rotor with three midspan disks to reduce the bending resonances with complete noncontact levitation. A high rotating speed of 6300 r/min was achieved, which is above the fifth bending critical speed     

Hardware Implementation on the Weight Calculation of Iterative Algorithm for CT Image Reconstruction

The weight calculation in an iterative algorithm is the most computationally costly task in computed tomography image reconstruction. In this letter, a fast algorithm to speed up the weight calculation is proposed. The classic square pixel rotation approximate calculation method for computing the weights in the iterative algorithm is first analyzed and then improved by replacing the square pixel model with a circular pixel model and the square rotation approximation with a segmentation method of a circular area. Software simulation and hardware implementation results show that our proposed scheme can not only improve the definition of the reconstructed image but also accelerate the reconstruction.     

半球动压气浮轴承有螺旋槽与无螺旋槽轴承特性仿真分析

本文采用CFD数值模拟方法和试验数据相结合的方式对半球型动压气浮轴承径向偏心3%和轴向偏心3%的流场进行分析.对轴承同一偏心率下有、无螺旋槽的轴径向刚度、轴径向承载力、姿态角、功率等特性进行了比较.结果表明,半球型动压气浮轴承的数值仿真结果与试验数据吻合较好.刻有螺旋槽的轴承,压力沿螺旋槽逐渐上升,在螺旋槽顶达到峰值,跨过螺旋槽后压力逐渐降低.由于圆周均布了多个螺旋槽,螺旋槽的导流作用使得高压区均匀的分布在轴承圆周面上.没有螺旋槽的轴承在径向偏心时存在一个对称分布的高压区和低压区,二者夹角近似180度,但在轴向偏心时却无法形成动压效应,轴承支撑力几乎为0.相比无螺旋槽的轴承,有螺旋槽压力分布更均匀,能提供轴、径向支撑力,且姿态角和功率更小,更有助于电机稳定的高速旋转.