Research On V - Type Double - Vibrator Linear Piezoelectric Actuator

For its easy miniaturization, rapid response, direct-driving, self-locking when power off and other advantages, piezoelectric actuators are widely applied in some fields with high requirement of accurate positioning, such as micro robots, aeronautics and astronautics, medical device, MEMS and so on. Based on the combination of precise screw driving and ultrasonic vibration of piezoelectric materials, a screw-type piezoelectric actuator was proposed, which could be served as the general driving unit for the equipment of micromachining or micro-operation.In response to the defects of bonded-type piezoelectric actuators, such as easy-falling off of piezoelectric ceramics, low output efficiency and so on, a v-shaped screw-type linear actuator with double piezoelectric vibrators was proposed in this paper. Slight vibration of particle on the surface of hollow cylinder was generated, which was excited by two piezoelectric vibrators. Through the effect of friction between nut and screw rod, the later was driven to rotate, directly driving the load to work. The piezoelectric vibrators adopted the sandwich-type structure, whose working mode is longitudinal working modal d33 mode.The piezoelectric effects and piezoelectric equations of piezoelectric material, and some other important parameters characterizing its properties were summarized in this paper. The vibration characteristics of hollow cylinder and elastic transducers were analyzed utilizing the theory of vibration separately, indicating that the piezoelectric vibrators vibrated cycling in the direction of left-right and up-down during the working process of actuator. The driving principle of actuator was further illustrated by analyzing the vibration trajectory of driving particle on the surface of hollow cylinder.The structure of actuator stator was designed, as well as the materials selected. The impact of structure parameters on the resonant frequency and amplitude of stator were investigated by means of finite element method(FEM), which optimized the structure of stator. The modal analysis and harmonic response analysis of stator were performed, and the theoretical working frequency of stator are obtained as 9.801 KHz. The prototype of piezoelectric actuator was fabricated, whose mechanical output performance were tested through corresponding experimental system. Through the analysis of experiment results, the correctness of theoretical analysis and simulation results were verified. The practical working frequency of prototype is tested as 9.7KHz, lower than the analysis result of ANSYS. The maximum no-load speed as well as output force are 1.202mm/s and 2.3N, respectively, under Vpp=300V. According to the working modal and corresponding frequency of stator, the dedicated driving power of actuator was designed as well.