Laminated Piezoelectric Element Crack Suppression
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Solution Overview
Problem
Multi-layer piezoelectric elements experience durability issues due to cracks at the interface between piezoelectric and internal electrode layers, which can disrupt electrical connections and reduce the element's lifespan.
Innovation Solution
The design incorporates external electrodes with protrusions that prevent cracks from propagating to the interface with the conductive bonding material, ensuring constant conduction and enhanced durability by anchoring the external electrode securely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layer piezoelectric element is driven, then the piezoelectric element performs its function through expansion and contraction, but cracks occur at interfaces or in internal electrode layers which pierce the conductive bonding material and reduce durability
Solution Approach 1:
The external electrode is extended in the stacking direction (vertical dimension) to form protrusions that reach into the conductive bonding material. This dimensional extension creates a three-dimensional anchoring structure that prevents crack propagation, transforming a two-dimensional surface electrode into a three-dimensional protective feature that spans across potential crack paths.
Solution Approach 2:
The protrusions of the external electrode are positioned beforehand to intercept and stop cracks before they can reach the interface between the conductive bonding material and the external electrode. By anticipating crack propagation paths and placing protective protrusions in advance, the design prevents harmful crack development before it can compromise electrical connection.
2Reliability
If cracks pierce the conductive bonding material, then electrical connection between external electrode and conductive bonding material is disrupted, but the invention maintains constant conduction
Solution Approach 1:
The external electrode extends in the stacking direction to form protrusions that penetrate into the conductive bonding material. This vertical extension creates multiple contact points along the depth of the bonding material, ensuring that even if cracks form at the surface, the electrical connection is maintained through the protruding portions that remain embedded in the bonding material.
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 effectively suppresses crack development and maintains reliable electrical connections, significantly improving the durability and longevity of multi-layer piezoelectric elements.
Implementation Method 1
a stacked body (4) in which piezoelectric layers (2) and internal electrode layers (3) are laminated
Data Source
AI summary
There are provided a multi-layer piezoelectric element capable of suppressing the development of a small crack occurring at an interface between a piezoelectric layer and an internal electrode layer or in the internal electrode layer, and a piezoelectric actuator, an injection device and a fuel injection system including the same. A multi-layer piezoelectric element (1) of the invention includes a stacked body (4) in which piezoelectric layers (2) and internal electrode layers (3) are laminated, and an external electrode (6) disposed on a side surface of the stacked body (4) and electrically connected to the internal electrode layers (3) through a conductive bonding material (5), the external electrode (6) including protrusions (61) protruding toward the stacked body (4).