Piezoelectric Fan with Bent Blade Base for Uniform Cooling
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Solution Overview
Problem
Piezoelectric fans with straight blades face issues of increased volume occupation and reliability due to blade protrusion and stress concentration, while fans with bent blades suffer from variations in resonant frequency and amplitude, leading to inefficient cooling and potential fatigue failure.
Innovation Solution
A piezoelectric fan design with a vibration plate having a right-angle bent portion before division into blades, where the piezoelectric element is attached between the fixed and bent portions, reduces stress concentration and resonant frequency variations, ensuring uniform blade amplitudes and improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If blades extend straight from the actuator portion, then the cooling effect is improved, but the occupied volume increases and reliability decreases
Solution Approach 1:
The blade is bent at a right angle at its base portion, changing the spatial orientation from a straight extension to a perpendicular configuration. This dimensional change allows the blade to extend in a direction perpendicular to the actuator portion, reducing the protrusion distance and occupied volume while maintaining cooling effectiveness
2Productivity
If blades extend straight from the actuator portion, then the cooling effect is improved, but reliability decreases due to stress concentration
Solution Approach 1:
The blade base portion is bent at a right angle instead of extending straight, creating a curved configuration that distributes stress more evenly. This curvature prevents stress concentration at the connection point between the blade and actuator portion, reducing the risk of cracks and improving long-term reliability
3Device complexity
If a single blade is attached to a single piezoelectric element, then the structure is simplified, but blades cannot be inserted between multiple fins and cooling efficiency decreases
Solution Approach 1:
The blade is divided into multiple segments (first blade portion and second blade portion) separated by a slit, while remaining integrally connected through the bent base. This segmentation allows the blade to be inserted between multiple fins of the heat sink, enabling efficient heat dissipation across multiple fin spaces while maintaining structural integrity
4Volume of moving object
If the blade is bent at a right angle, then the occupied space is reduced, but variations in resonant frequency among blades increase
Solution Approach 1:
The blade base portion is pre-bent at a right angle at a position before the division into multiple blade segments. This preliminary action of bending before segmentation ensures that all blade segments share the same structural configuration and material properties, resulting in uniform resonant frequencies across all blades while maintaining compact dimensions
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 enhances cooling efficiency and durability by minimizing blade protrusion, reducing stress concentration, and achieving uniform cooling effects across all blades, while maintaining a compact form factor.
Implementation Method 1
a piezoelectric element attached on at least one of front and back surfaces of the vibration plate, wherein an air stream is generated by vibrating the vibration plate in the thickness direction thereof through driving of the piezoelectric element
Data Source
AI summary
A piezoelectric fan includes a vibration plate one end of which in a length direction is supported in a fixed manner and the other end of which in the length direction is a free end; and piezoelectric elements, attached on at least one of front and back surfaces of the vibration plate. In an intermediate portion of the vibration plate in the length direction, a right-angle bent portion is provided, and a plurality of divided blades are defined by slits in an area of the vibration plate extending from the free end to a position located a predetermined distance from the bent portion toward the free end. The piezoelectric element is attached on the portion of the vibration plate between the fixed end and the bent portion. Hence, variations in resonant frequency among the blades are reduced and the blades are efficiently excited using a common piezoelectric element.