【作者】 杨淋；

【导师】 赵淳生；

【作者基本信息】 南京航空航天大学 ， 机械电子工程， 2010， 博士

【摘要】 纵扭复合型超声电机与其它类型的超声电机相比,因为扭矩/体积比大的优点而成为近年来国内外研究的热点之一。可是传统的纵扭复合型超声电机也存在不足之处:一是纵振利用效率不高,接触界面摩擦损耗较高;二是使用扭振陶瓷片使得电机的设计变得复杂以及成本大大增加;三是电机不易于小型化。针对上述三点,本文提出了应力型纵扭复合超声电机、纵扭模态转换型超声电机以及基于d₃₁效应的贴片式纵扭复合超声电机。应力型纵扭复合超声电机中的纵振压电陶瓷片位于接触界面上,能有效地控制接触压力,从而提高电机的输出力矩;纵扭模态转换型超声电机只利用纵振压电陶瓷片,扭振由纵振转换而得,从而简化了电机结构,降低了设计难度和加工成本;基于d₃₁效应的贴片式纵扭复合超声电机则利用基于d₃₁效应的压电陶瓷通过粘贴的方式来激励电机的纵振和扭振模态,易于小型化。主要研究内容和成果综述如下:（1）分析了压电陶瓷通过诱发应变来实现电能到机械能转换的工作机理,研究了纵扭复合型超声电机工作过程中定子端面质点椭圆运动轨迹的形成机理以及电机的驱动机理,提出了一种新的纵扭复合型超声电机分类方式。（2）研制了两种应力型纵扭复合超声电机。分别对单转子和双转子应力型纵扭复合超声电机进行了结构设计,提出了纵振压电陶瓷片全部放置在定子端面上的结构。利用有限元分析软件ANSYS详细分析了影响定子1阶扭振模态和电机整体2阶纵振模态的结构参数,并提出了针对应力型纵扭复合超声电机的模态频率一致性设计方法。分别对这两种应力型纵扭复合超声电机进行了实验研究,其中,Φ20mm双转子应力型纵扭复合超声电机堵转力矩达到了1.28N·m,而目前世界上已报导Φ20mm超声电机最高堵转力矩仅有0.8 N·m。（3）研制了两种纵扭模态转换型超声电机。在对斜槽式纵扭模态转换型超声电机的研究的基础上,提出了孔式模态转换型超声电机。分析了纵扭振模态转换机理,研究了两种纵扭模态转换型超声电机中各项参数对电机频率、纵/扭振位移幅值的影响,并以输出最大力矩为目标,对斜槽式和孔式电机定子分别进行了结构动力学优化。分析了纵扭模态转换型超声电机定/转子之间的接触情况,并在此基础上利用冲量定理建立了电机定/转子之间的动力传递模型,定量分析了接触界面上的能量损耗以及动力传递效率。利用该模型可以仿真各种预压力情况下,定子纵振振幅和扭振振幅、预压力、摩擦材料等因素对电机机械特性的影响。（4）研制了两种新型贴片式纵扭复合型超声电机。分析了圆管中有纵、扭振动波传播时的应力状况,据此提出了单向和双向两种贴片式纵扭复合型超声电机。提出了基于d₃₁效应的全新纵、扭振激励机理。研究了这两种电机的压电陶瓷的极化和布置方案,并提出了电激励方式,分析了使纵、扭振模态频率一致的方法。最后通过实验的方法验证了激励机理的可行性,并研制了两台样机,分别成功实现了单向转动和双向转动。（5）对纵扭模态转换型超声电机进行了实验研究,提出了适用于纵扭复合型超声电机的最佳摩擦副以及最佳预压力弹簧。分析了定/转子在工作过程中的接触情况,以及在不同摩擦副和不同预压力弹簧下,电机输出机械特性的变化情况,分析得出结论:对于纵扭复合型超声电机,使用硬/软摩擦副以及非线性强的预压力弹簧有助于提高电机的输出机械特性。研制的Φ15mm孔式模态转换型样机最佳性能数据为:空载转速1082 r/min,堵转力矩0.32N·m,最大效率32.3%;而目前已报导Φ15mm模态转换型超声电机对应的最佳性能数据为:1100 r/min,0.4N·m以及22%。更多还原

【Abstract】 Hybrid ultrasonic motor using longitudinal-torsional vibration modes (LTUSM), which has become a hot spot of technical research, has larger ratio of torque to volume than other types of ultrasonic motor(USM). However, conventional LTUSM has some deficiencies. Firstly, utilization ratio of longitudinal vibration is not high; friction loss at the contact surface between the stator and rotor is large. Secondly, design of the motor becomes complex and cost increases greatly as torsional PZTs are used. Thirdly, the LTUSM is difficult to miniaturize. In view of these three questions, stress-type LTUSM, LTUSM using mode conversion and surface mount type LTUSM based on d31 effect were presented. The stress-type LTUSM has longitudinal PZTs at the contact surface, which can control contact pressure effectively and improve output torque of the motor. The LTUSM using mode conversion whose torsional vibration is converted from longitudinal vibration uses only longitudinal PZT, thus, motor structure will be simplified and design will be easy to implement and the cost will be reduced. The piezoelectric ceramics with d31 effect are used in the surface mount type LTUSM based on d31 effect, whose longitudinal and torsional modes are excited by mount ceramics on the surface of the motor, this type of motor is easy to miniature.The main contributions of the dissertation were summarized as follows:(1) The working mechanism which converts electrical to mechanical energy by strain of PZT was analyzed. Elliptic trajectory formation mechanism of particle on the stator surface and driving mechanism for the LTUSM during the working were studied. A new classification method for the LTUSM was proposed.(2) Two kinds of stress-type LTUSM were developed. Structure designs were carried out to the stress-type LTUSM with one rotor and the stress-type LTUSM with two rotors respectively. It was put forward that the lonigitudinal PZT should be placed on the surface of the stator. The FEA software ANSYS is used to anlysis the structure parameters which affect the 1st torsional vibration mode and the 2nd longitudinal vibration mode and the method to realize the frequency coherence between the 1st torsional vibration mode and the 2nd longitudinal vibration mode was put forward. The experiments for the stress-type LTUSM with two rotors shows that the stalling torque of the motor with diameter in 20mm has reached 1.28 N·m, however the world’s top level is 0.8 N·m.(3) Two kinds of LTUSM using mode conversion were developed. The LTUSM using mode conversion with holes was put forward based on the research of LTUSM using mode conversion with slots. Based on ANSYS software, the effects that parameters of LTUSM using mode conversion had on mode frequency and amplitudes of longitudinal and torsional vibrations were studied. Aiming at large torque, the stators of the two kinds of LTUSM using mode conversion were optimized. According to contact situation between the stator and the rotor, force transmitting model between the stator and rotor was proposed by using theorem of impulse; energy loss and force transmitting efficiency were studied. Simulation results brought out the effects that when the motor operates steadily, the amplitudes of longitudinal and torsional vibrations, pre-pressure and friction material had on output mechanical characteristics.(4) Two kinds of the surface mount LTUSM based on d31 effect were developed. Stress states of the pipe when the longitudinal wave and torsional wave travel in the pipe are studied, and the unidirectional and bidirectional surface mount LTUSM based on d31 effect were put forward.A new exicting mechanism for longitudinal and torsional vibration mode was put forward. The polarization and arrangement of the PZT are studied, and the exciting method and the method to realize the frequency coherence between the 1st torsional vibration mode and the 2nd longitudinal vibration mode are presented. Two prototypes were developed and realized unidirectional and bidirectional rotation respectively.(5) Testing of the LTUSM using mode conversion was carried out, best friction pair and best pre-pressure spring for the LTUSM was put forward. Contact situation between the stator and the rotor under operating conditions and output mechanical characteristics under various friction pairs and pre-pressure springs were studied. Conclusions can be gotten: Using hard/soft friction pairs and pre-pressure spring with strong nonlinearity can help improve the output mechanical characteristics. No-load speed of the prototype with 15mm in diameter can reach 1082 r/min, stalling torque can reach 0.32 N·m, and the maximal efficiency can reach 32.3%, however, the world’s top level for the same motor are 1100 r/min, 0.4N·m and 22%.更多还原