Multi-spoke Ultrasonic Motor Stator Design
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Solution Overview
Problem
Miniaturization of direct current motors leads to increased Joule heat loss and decreased mechanical performance, while existing ultrasonic motors face challenges in reducing machining precision requirements and increasing mechanical performance.
Innovation Solution
A multi-spoke-type ultrasonic motor design featuring a rotating shaft, fastening sleeve, spring, rotor, stator with internal spoke-like teeth, and piezoelectric ceramics, where the stator's spoke-like teeth are rotationally symmetrical and angled to optimize contact and vibration, reducing machining precision needs and enhancing mechanical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of direct current motor is decreased, then miniaturization is achieved, but Joule heat loss increases sharply and drive capability decreases
Solution Approach 1:
The patent replaces the electromagnetic drive system of traditional DC motors with an ultrasonic vibration-based mechanical drive system. The stator generates ultrasonic vibrations that transmit frictional force to the rotor, eliminating the need for electromagnetic fields and windings that cause Joule heating. This substitution of drive mechanism fundamentally resolves the energy loss issue while enabling miniaturization.
Solution Approach 2:
The patent utilizes ultrasonic mechanical vibration as the core driving mechanism. The stator is designed to vibrate at ultrasonic frequencies, creating a traveling wave that propels the rotor through friction. This vibration-based approach allows for extremely compact motor dimensions while maintaining efficient energy conversion without the thermal losses inherent in electromagnetic systems.
2Volume of moving object
If the size of ultrasonic motor is decreased, then miniaturization is achieved, but machining precision requirements increase rapidly
Solution Approach 1:
The stator is segmented into multiple independent vibration units (spoke-like structures) that can vibrate independently. This segmentation allows each unit to be manufactured with lower precision requirements, while the collective arrangement maintains the overall traveling wave pattern. The modular design reduces the cumulative precision demands compared to a monolithic structure.
Solution Approach 2:
The patent employs asymmetric spoke-like structures with specific geometric parameters (angle α between 0° and 90°, angle θ optimized for contact) that are intentionally designed to be asymmetric relative to the stator center. This asymmetry creates the necessary traveling wave pattern while allowing for tolerance in manufacturing, as the functional performance depends on the relative geometry between components rather than absolute precision of each element.
3Power
If existing ultrasonic motor structure is used, then drive capability is maintained, but output performance is limited and service life is reduced
Solution Approach 1:
The rotor is designed with a hemispherical or tapered curved surface that contacts the stator's spoke-like structures. This curvature distributes the contact stress across a larger area, reducing localized wear and frictional heating. The curved geometry also better conforms to the vibration pattern, improving energy transfer efficiency and thus output performance while extending component life through reduced mechanical degradation.
Solution Approach 2:
The stator features localized spoke-like structures with specific geometric properties (angles α and θ, varying lengths) optimized for different regions. This local quality variation allows different parts of the stator to perform specialized functions - some regions optimized for force generation, others for stress distribution - thereby enhancing overall output performance while reducing peak stresses that would limit service life.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves improved output torque and speed, reduced manufacturing costs, low drive voltage, and increased service life, making it suitable for micro applications and large-scale industrial use.
Implementation Method 1
an ultrasonic motor transforms electric energy into mechanical energy by using the inverse piezoelectric effect
Implementation Method 2
transforms electric energy into mechanical energy by using the inverse piezoelectric effect and the friction effect of a material
Data Source
AI summary
A multi-spoke-type ultrasonic motor has: a rotating shaft (1), a fastening sleeve cylinder (2), a spring (3), a rotor (4), a stator (5), a fastening screw (6), and piezoelectric ceramics (7). The rotor (4), the stator (5), the spring (3), and the fastening sleeve cylinder (2) are sequentially connected via the rotating shaft (1). The stator (5) is an annular metal plate having internal spoke-like teeth. The upper surface and the lower surface of the stator (5) are provided with identical stator spoke-like teeth for contacting the rotor (4). The rotor (4) and the stator (5) are in close contact under the effect of prestressing of the spring (3). The piezoelectric ceramics (7) are annular plates; upper and lower plates respectively are affixed on the upper and lower surfaces of the stator (5). The motor is capable of increasing the output power of the ultrasonic motor.