Abstract
To realize applications involving low speed and high torque in the high-performance actuator industry, especially in the aerospace field, we propose a novel 70H traveling wave rotary ultrasonic motor (TRUM) with an outer diameter of 70 mm and an aperture ratio of 53% (the ratio between the aperture and outer diameter). The power transmission mechanism between the stator and the rotor is analyzed, and a method for realizing low-speed–high-torque characteristics of TRUMs is proposed. ANSYS software is used to simulate the modal parameters of the stator, and the ratio β between the normal amplitude and the tangential vibration velocity of the stator is proposed. The larger the value of β, the lower the speed and the higher the torque. Furthermore, two prototype motors are fabricated, namely, 70HA and 70HB. Compared with 70HA, the maximum no-load speed of the improved 70HB (50 rpm) is decreased by 23.1% and the maximum stall torque (2.4 N∙m) is increased by 100%. Besides this, with a smaller mass of 210 g and a higher torque density of 11.43 N∙m/kg, 70HB has fundamentally different mechanical characteristics.
Highlights
Traveling wave rotary ultrasonic motors (TRUMs) have been widely developed worldwide.Compared with electromagnetic motors, traveling wave rotary ultrasonic motor (TRUM) have drawbacks of lower efficiency and durability, but there are still some unique advantages
Previous studies have shown that the TRUM limiting speed is inversely proportional to the square of the outer diameter and the output torque is proportional to the square of the outer diameter; the first method involves increasing the outer diameter [3,4,5]
We propose the 70H: a hollow TRUM with an outer outer diameter diameter of of ∅
Summary
Traveling wave rotary ultrasonic motors (TRUMs) have been widely developed worldwide. Because of the limitation of their driving mechanism, TRUMs have poorer low-speed–high-torque characteristics compared with those of standing wave ultrasonic motors (SUMs). ∅60 mm dual traveling wave rotary ultrasonic motor with a maximum speed and stall developed a ∅60 mm dual traveling wave rotary ultrasonic motor with a maximum speed and torque of 60ofrpm andand. Kawai et al developed a ∅70 mm double-piezoelectric-ceramic motor with with aa maximum rpm and [11]. Tian et al developed a ∅90 mm hollow-ring motor with a maximum speed and stall torque of 106 rpm. Developed a ∅100 mm large-torquepressure-equalizing pressure-equalizingmotor motor with a maximum speed and stall torque of rpm and [14]. Chen with a maximum speed and stall torque of 58 rpm and 2.2 N·m, respectively [14].
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