Piezoelectric Vibrating Plate Segmentation for Stress Reduction
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Solution Overview
Problem
Piezoelectric driving devices for motors face challenges in efficiently rotating rotors due to stress concentration and reduced output caused by variations in the position of the vibrating plate relative to the fixation member, leading to increased differences in resonance frequencies and reduced reliability.
Innovation Solution
A piezoelectric driving device design where the fixed portion, vibrator portion, and contact portion are aligned in the X direction, with a smaller cross-sectional area of the connection portion compared to the base and vibrator portions, to minimize stress concentration and maintain resonance frequency differences even with varying plate positions, and incorporating multiple piezoelectric elements for enhanced force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor is disposed to come into contact with the main surface of the vibrating plate, then the vibrating plate can transmit motion to the rotor, but stress concentrates on the boundary between the fixed portion and vibrating portion causing damage and limiting pressing force
Solution Approach 1:
The vibrating plate is divided into three distinct portions: fixed portion, connection portion, and vibrator portion. This segmentation allows stress to be distributed across different regions, preventing concentration at the boundary between fixed and vibrating areas, thereby enabling increased pressing force without compromising structural integrity.
Solution Approach 2:
Different portions of the vibrating plate are designed with different properties: the fixed portion provides stable attachment, the connection portion (with smaller cross-sectional area) acts as a stress-relieving transition zone, and the vibrator portion enables effective motion transmission. This local differentiation optimizes both strength and power transmission.
2Speed
If the arm portion is made thin and long to avoid disturbing vibration, then vibration disturbance is minimized, but the arm portion becomes susceptible to shear stress damage
Solution Approach 1:
The connection portion is designed with a smaller cross-sectional area than both the base portion and vibrator portion, creating a localized weak point that flexes under stress. This local quality differentiation allows the connection portion to absorb shear stresses while the thinner vibrator portion maintains its vibration characteristics undisturbed.
3Ease of operation
If the position of the vibrating plate relative to the fixation member varies, then assembly flexibility is improved, but the difference between resonance frequencies increases reducing rotational efficiency
Solution Approach 1:
Dividing the vibrating plate into fixed portion, connection portion, and vibrator portion creates a structure where the connection portion can accommodate positional variations during assembly. This segmentation isolates the vibrator portion's resonance characteristics from positioning errors, maintaining rotational efficiency despite assembly flexibility.
Solution Approach 2:
The connection portion acts as an intermediary element between the fixation member and the vibrator portion. It absorbs positional mismatches and stress variations, ensuring that the vibrator portion maintains its intended resonance frequencies and operational efficiency even when assembly position varies.
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
This design achieves high output and reliability by reducing stress on the vibrating plate and maintaining consistent resonance frequency differences, even when the vibrating plate's position varies, thus efficiently rotating the rotor and increasing the force applied to the driven body.
Implementation Method 1
a vibrator portion (46) in which a piezoelectric element (50) is provided
Implementation Method 2
resonance vibration in a primary longitudinal vibration mode in a longitudinal direction of the elastic plate including one fixed edge and the other free edge, and resonance vibration in a higher bending vibration mode in a longitudinal direction
Implementation Method 3
a contact portion (60) which comes into contact with a driven body (2) and transmits motion of the vibrating plate (40) to the driven body (2)
Data Source
AI summary
Provided is a piezoelectric driving device for a motor including: a vibrating plate which includes a fixed portion and a vibrator portion in which a piezoelectric element is provided and which is supported by the fixed portion; and a contact portion which comes into contact with a driven body and transmits motion of the vibrating plate to the driven body, in which the fixed portion, the vibrator portion, and the contact portion are provided along an X direction in this order, when seen in a Y direction, when two directions parallel to a main surface of the vibrating plate and orthogonal to each other are set as the X direction and the Y direction and a direction orthogonal to the main surface of the vibrating plate is set as a Z direction.