Surface acoustic wave motor with sapphire wave guide

2019 Fiscal Year Final Research Report

• Project/Area Number: 15H03943
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Intelligent mechanics/Mechanical systems
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Kurosawa Minoru 東京工業大学, 工学院, 准教授 (70170090)
• Project Period (FY): 2015-04-01 – 2020-03-31
• Keywords: アクチュエータ / 圧電アクチュエータ / 超音波モータ / リニアモータ / マイクロモータ / 弾性表面波素子 / 摩擦駆動 / MEMS

Outline of Final Research Achievements

The surface acoustic wave (SAW) motor, as a type of traveling wave ultrasonic motor, has been studied for years. A Rayleigh wave is excited by a unidirectional interdigital transducer (U-IDT) in a lithium niobate stator. Through frictional force, a driven slider can achieve linear motion. At the contact surfaces of the stator and slider, one problem observed is the lack of tolerance to wear. Owing to the large mohs hardness, a novel approach to the fabrication of a sapphire stator is investigated to improve frictional durability. In the novel sapphire stator, the Rayleigh wave, generated by the lithium niobate U-IDT transducer, is transmitted to the sapphire stator surface through pure mechanical integration. Through measurement results, the sapphire stator is evaluated via the admittance characteristics of the wave excitation unit, the normal vibration of the Rayleigh wave, and the horizontal vibration velocity of the Rayleigh wave.

Free Research Field

超音波工学

Academic Significance and Societal Importance of the Research Achievements

サファイアと同じ組成であるアルミナ・セラミクスを摩擦材として実用化された超音波モータでは，動作距離10,000km（推定10,000時間）の寿命を実現している。アルミナ・セラミクスの単結晶材料であるサファイアを摩擦駆動部に用いることで高い耐久性が期待できる。振動発生部には，単結晶ニオブ酸リチウムを用いることで高いパワー密度を実現し，摩擦駆動部には，耐摩耗性と機械強度に優れた単結晶サファイアを用いることで高い耐久性を目指しているのが，本弾性表面波モータである。