Piezoelectric Actuator with Segmented Bodies and Exposed Shim

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Solution Overview

Problem

Piezoelectric actuators face a trade-off between achieving large displacement and high resonance frequency, making it difficult to design an actuator that satisfies both requirements effectively.

Innovation Solution

The actuator incorporates a first and second piezoelectric body with a shim material disposed between them, where one end is fixed and the other end is free, allowing the shim material to be exposed, which helps in achieving a balance between displacement and resonance frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the piezoelectric body length is increased to achieve large displacement, then the displacement amount increases, but the resonance frequency decreases

Engineering Contradiction:

Improvedisplacement amountVSAvoidresonance frequency

Core Design Contradiction:

Length of moving objectVSSpeed

Solution Approach 1:

The actuator is divided into multiple piezoelectric bodies (first and second piezoelectric bodies) arranged in series along the axial direction. This segmentation allows the total displacement to be accumulated across multiple segments while each segment maintains a length that preserves high resonance frequency characteristics.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a single longitudinal dimension approach to a multi-dimensional configuration by stacking piezoelectric bodies in the axial direction while exposing shim materials at the end face. This dimensional arrangement enables independent optimization of displacement (through series stacking) and resonance frequency (through controlled exposure length).

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Speed

If the piezoelectric body length is decreased to achieve high resonance frequency, then the resonance frequency increases, but the displacement amount decreases

Engineering Contradiction:

Improveresonance frequencyVSAvoiddisplacement amount

Core Design Contradiction:

SpeedVSLength of moving object

Solution Approach 1:

Multiple piezoelectric bodies are merged in a series configuration along the axial direction, where the displacement of each body accumulates to produce large total displacement. The shim materials are also merged into the assembly and exposed at the end face to maintain resonance frequency while supporting the stacked structure.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The actuator employs a composite structure combining piezoelectric bodies with shim materials (different material properties). This composite arrangement allows the piezoelectric bodies to generate displacement while the exposed shim materials at the end face control the resonance characteristics, achieving both large displacement and high resonance frequency simultaneously.

Inventive Principle:

Principle #40Composite materials

3Length of moving object

If the actuator mass is increased to achieve large displacement, then the displacement amount increases, but the resonance frequency decreases

Engineering Contradiction:

Improvedisplacement amountVSAvoidresonance frequency

Core Design Contradiction:

Length of moving objectVSWeight of moving object

Solution Approach 1:

The invention extracts and exposes the shim materials at the end face of the actuator, separating their function from the bulk mass of the piezoelectric bodies. This extraction allows the shim materials to contribute to displacement through their exposed length while minimizing their contribution to overall mass, thereby maintaining high resonance frequency.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The shim materials are strategically positioned and exposed only at the end face region rather than being distributed throughout the entire actuator length. This local quality approach concentrates the mass-reducing effect at the critical end region where it most effectively preserves resonance frequency while still enabling sufficient displacement through the stacked piezoelectric bodies.

Inventive Principle:

Principle #3Local quality

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 configuration enables the actuator to achieve a large displacement amount while maintaining a high resonance frequency, improving performance by reducing the mass at the tip end and securing sufficient length for displacement.

Implementation Method 1

An actuator including a piezoelectric body applies an electric field to the piezoelectric body to cause the piezoelectric body to expand and contract and generate a driving force

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS20230217828A1actuator

Publication Date: 2023.07.06 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

Provided is an actuator including a piezoelectric element capable of satisfying three of a large amplitude, a high resonance frequency, and a large generated force. Actuator (100) is a drive source having a cantilever structure in which one end is a fixed end and the other end is displaced, and includes first piezoelectric body (110), second piezoelectric body (120), and shim member base (130) disposed between first piezoelectric body (110) and second piezoelectric body (120). In first piezoelectric body (110) and second piezoelectric body (120), piezoelectric body removal parts (110a) and (120a) are formed.