Vibration Wave Motor Piezoelectric Layout for Efficient Drive
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Solution Overview
Problem
Existing vibration wave motors using piezoelectric elements face challenges in efficiently vibrating while maintaining low manufacturing costs, particularly due to the increased pressure and processing complexities associated with rectangular-shaped piezoelectric elements.
Innovation Solution
A vibration wave motor design that includes a first and second elastic body, an electromechanical energy conversion element sandwiched between them, and a contact body for pressure contact. The electromechanical energy conversion element has a rectangular cross-section perpendicular to the pressure direction, with its vertices not in contact with the elastic bodies, allowing for efficient vibration and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rectangular piezoelectric element is used, then manufacturing cost is reduced by eliminating outer shape processing, but pressure increases toward the outer diameter side causing inefficient vibration
Solution Approach 1:
The rectangular piezoelectric element is segmented by providing gaps between the elastic body and the vertices of the rectangle. This segmentation prevents stress concentration at the vertices while maintaining the cost advantages of rectangular geometry, thereby resolving the contradiction between manufacturing ease and vibration efficiency.
Solution Approach 2:
The elastic body acts as an intermediary element that mediates between the rectangular piezoelectric element and the circular contact body. By carefully designing the gaps and contact areas, the elastic body distributes pressure uniformly and prevents direct contact at vertices, thus maintaining vibration efficiency while allowing rectangular geometry for cost reduction.
2Power
If the distance from axial center in radial direction is increased, then power is increased, but pressure increases toward outer diameter side causing inefficient vibration
Solution Approach 1:
The design applies local quality by creating different contact conditions in different regions of the piezoelectric element. The vertices (outer regions) are prevented from contacting the elastic body to avoid stress concentration, while the midpoints of sides (inner regions) maintain contact for force transmission. This local differentiation allows increased radial distance for power while maintaining vibration efficiency.
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 proposed design enables efficient vibration performance with high driving efficiency while reducing manufacturing costs by avoiding complex processing requirements and maintaining efficient energy conversion.
Implementation Method 1
a Langevin vibrator configured by sandwiching the piezoelectric element by elastic bodies made of stainless steel and the like. The driving principle is that elliptical motion or circular motion is generated on surfaces of the elastic bodies by generating two bending vibrations orthogonal to each other on the vibrator by application of a predetermined alternating-current voltage
Implementation Method 2
the rotor is rotationally moved by frictional force
Data Source
AI summary
In a vibration wave motor that includes a first elastic body and a second elastic body, a piezoelectric element (electromechanical energy conversion element) sandwiched between the first elastic body and the second elastic body, and a contact body configured to come into pressure contact with the first elastic body, an outer shape of a cross-section (XY plane) in the piezoelectric element perpendicular to a pressure direction (Z direction) in pressure contact between the first elastic body and the contact body is a rectangle, and vertices of the rectangle of the piezoelectric element are not in contact with the first elastic body.