Piezoelectric Actuator Laser Trench Insulation
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Solution Overview
Problem
Existing piezo actuators with multiple layers and internal electrode layers suffer from significant inactive zones due to production tolerances and insulation requirements, leading to mechanical stresses and the risk of polarity cracks, especially when a large adjustment path is needed.
Innovation Solution
A method involving a fully active piezo stack with continuous internal electrode layers, where trenches are created using a laser and filled with insulating material to minimize inactive zones, ensuring electrical insulation while reducing the risk of polarity cracks by making the trenches as small as necessary for effective electrical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inner electrode layers are recessed from the outside to ensure electrical insulation, then electrical insulation is improved, but inactive zones increase leading to mechanical stresses and polarity cracks
Solution Approach 1:
The patent replaces the conventional mechanical recessing method with a laser-based approach. The laser selectively removes material to create precise trench structures that provide electrical insulation without requiring large recesses, thereby minimizing inactive zones and reducing mechanical stresses while maintaining reliable electrical insulation.
Solution Approach 2:
The patent changes the geometric parameters of the insulation structure by using laser processing to create trenches with optimized depth and width. This allows the inactive zones to be minimized to the smallest necessary dimensions for electrical insulation, reducing the 10% cross-sectional area mentioned in the background while ensuring adequate insulation between inner electrode layers and outer electrodes.
2Ease of manufacture
If conventional production methods are used with stacking and grinding, then manufacturing is simplified, but production tolerances result in large inactive zones
Solution Approach 1:
The patent replaces conventional mechanical stacking and grinding processes with laser-based processing. The laser directly processes the green body or sintered ceramic to create precise trench structures for electrical insulation, eliminating the accumulation of tolerances from multiple stacking and grinding operations that result in large inactive zones.
Solution Approach 2:
The patent extracts the insulation function from the mechanical stacking process and implements it through laser-created trench structures. This separates the insulation requirement from the assembly tolerances, allowing precise control of inactive zone dimensions independent of stacking and grinding tolerances.
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 approach results in a piezo actuator with minimized inactive zones, reducing the risk of mechanical stresses and polarity cracks, and simplifies the manufacturing process by maintaining the stack's active nature throughout, enhancing reliability and performance.
Implementation Method 1
providing the outside of the fully active piezo stack with trenches in areas where the inner electrode layers should be electrically isolated from the corresponding outer electrodes, so that the trenches shorten the inner electrode layers in these areas from the outside of the piezo stack inwards, using the laser
Implementation Method 2
The function of a piezo element is based on the deformation of piezoceramic materials, such as lead zirconate titanate, under the influence of an electric field. If an electrical voltage is applied to the piezo element, it expands in the direction perpendicular to the electrical field generated by the electrical voltage.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a piezoelectric actuator and to a method for producing a piezoelectric actuator (20, 70) having a piezo stack (1'', 1''') and two outer electrodes (11, 12, 11', 12') which are arranged on the outside (5) of the piezo stack (1'', 1'''). A fully active piezo stack (1) comprising a plurality of alternately successive piezoelectric layers (2) and continuous inner electrode layers (3, 4) is first of all provided. The outside (5) of the fully active piezo stack (1) is provided with trenches (7, 8) in regions in which the inner electrode layers (3, 4) are intended to be electrically insulated from the outer electrodes (11, 12, 11', 12'), with the result that the trenches (7, 8) shorten the inner electrode layers (3, 4) in these regions from the outside (5) of the piezo stack (1) inwards. The trenches (7, 8) are then filled with an electrically insulating material (9) and the two outer electrodes (11, 12, 11', 12') are applied to the outside (5) of the piezo stack (1'', 1'''), with the result that the two outer electrodes (11, 12, 11', 12') are alternately electrically connected to the inner electrode layers (3, 4).