Piezoelectric Micro-blower Segmented Openings Noise Reduction
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Solution Overview
Problem
Existing piezoelectric micro-blowers suffer from high noise levels due to significant speed differences in airflow, which interfere with the discharge flow rate and pressure, leading to inefficient fluid dynamics and increased noise.
Innovation Solution
A piezoelectric micro-blower design featuring a vibrating plate with multiple first openings and corresponding second openings, where the diameter of the second openings is one to three times that of the first openings, arranged to face each other, reducing noise by dispersing airflow speed and preventing backflow, thus enhancing flow rate and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single large opening is used for fluid discharge, then the flow rate can be increased, but the airflow speed difference becomes significant causing high noise levels
Solution Approach 1:
The single large opening is divided into multiple smaller openings (first openings and second openings). This segmentation disperses the airflow speed across multiple outlets, reducing the significant speed difference that causes noise while collectively maintaining high flow rate capability. Each small opening generates lower velocity flow, and the combined effect of multiple openings achieves the desired productivity without the harmful noise of a single large opening.
2Productivity
If the diameter of discharge openings is increased, then the flow rate improves, but the airflow velocity becomes too high causing backflow and noise
Solution Approach 1:
The discharge system uses multiple small-diameter openings instead of a single large opening. This maintains adequate total flow area for high productivity while keeping individual opening velocities low enough to prevent backflow and reduce noise.
Solution Approach 2:
The harmful high-velocity jet flow is extracted and replaced with multiple low-velocity flows. By taking out the single high-speed flow path and replacing it with multiple low-speed paths, the system eliminates backflow problems while maintaining overall flow rate through the combined effect of multiple openings.
3Productivity
If a fixed wall is used opposite the vibrating plate, then the structure is simple, but the flow rate cannot be significantly increased
Solution Approach 1:
The fixed wall opposite the vibrating plate is segmented to include multiple openings instead of being a continuous solid surface. This segmented structure allows significantly increased flow rate by providing multiple discharge paths while maintaining relative structural simplicity through the use of standard plate with holes configuration.
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
The design significantly reduces noise by dispersing airflow speed, increases the drawn fluid region, and maintains high flow rates by preventing backflow, resulting in improved fluid dynamics and reduced sound pressure levels.
Implementation Method 1
a piezoelectric micro-blower which employs a diaphragm which bends when a voltage is applied to a piezoelectric element
Implementation Method 2
A first wall portion 124 is provided at a location facing the vibrating plate 121 across the blower chamber 123 and resonates with vibrations of the vibrating plate 121
Implementation Method 3
air is discharged in the orthogonal direction of the holes 115 while the air around the holes 115 formed in the central portion of the second membrane 114 is sucked or drawn, whereby an inertial jet (jet) can be generated
Data Source
Figure 1~2
Figure 3~4
Figure 5(a)~6
AI summary
[Object] To provide a piezoelectric micro-blower having low noise while maintaining the flow characteristic. [Solution] A piezoelectric micro-blower includes: a blower chamber 3 formed between a blower body 1 and a vibrating plate 20; a first wall portion 11 of the blower body provided in a location facing the vibrating plate across the blower chamber for vibrating with vibrations of the vibrating plate; a first opening 12 formed in the first wall portion; a second wall portion 51 provided on the opposite side of the first wall portion with respect to the blower chamber; a second opening 52 formed in a portion of the second wall portion which faces the first opening; and an inflow passage 6 formed between the first wall portion and the second wall portion. Each of the first opening 12 and the second opening 52 is composed of a plurality of holes, and each hole of the first opening and each hole of the second opening are provided in positions facing each other. Thus, noise can be reduced while the flow characteristic is maintained.