Synthetic Jet Actuator Diaphragm Displacement Control via BEMF

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Solution Overview

Problem

Synthetic jet actuators often operate at suboptimal diaphragm displacements due to variations in environmental factors and aging, leading to inefficiencies in heat dissipation and potential mechanical failure from excessive displacement.

Innovation Solution

The method involves periodically adjusting diaphragm displacement by controlling velocity, using Back Electromotive Force (BEMF) measurements to recalibrate the actuator during operation, ensuring optimal performance and minimizing energy consumption, and utilizing BEMF to maintain specified displacement despite changes in temperature or age.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If diaphragm displacement is increased to improve heat dissipation performance, then cooling efficiency is improved, but mechanical failure risk increases due to excessive displacement

Engineering Contradiction:

Improveheat dissipation performanceVSAvoidmechanical failure risk

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements dynamic control of diaphragm displacement by periodically adjusting the drive voltage frequency and amplitude based on real-time BEMF measurements. This allows the system to adapt diaphragm displacement to optimal values for heat dissipation while preventing excessive displacement that would cause mechanical failure, thus resolving the contradiction between productivity and reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses BEMF measurements as feedback to continuously monitor and adjust diaphragm displacement. By measuring BEMF voltage across the coil and using it to control velocity and displacement, the system maintains displacement within safe operational limits while optimizing heat dissipation performance, preventing both underperformance and mechanical failure.

Inventive Principle:

Principle #23Feedback

2Reliability

If diaphragm displacement is decreased to prevent mechanical failure, then reliability is improved, but heat dissipation efficiency deteriorates

Engineering Contradiction:

Improvemechanical failure preventionVSAvoidheat dissipation efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

Rather than using a static displacement limit, the system dynamically adjusts displacement based on real-time BEMF measurements and operating conditions. This allows the system to operate at maximum safe displacement for optimal heat dissipation while automatically reducing displacement only when necessary to prevent mechanical failure, thus resolving the contradiction between reliability and productivity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters (drive voltage frequency, amplitude, and phase) based on BEMF measurements to optimize diaphragm displacement. By adjusting these parameters dynamically, the system maintains displacement at optimal levels for heat dissipation while preventing excessive displacement that would cause mechanical failure.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If BEMF measurement and control system is added to optimize displacement, then performance and energy efficiency are improved, but device complexity increases

Engineering Contradiction:

Improveperformance optimizationVSAvoidcontrol system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system uses the existing coil as both actuator and sensor by measuring BEMF voltage generated during diaphragm motion. This self-service approach eliminates the need for separate sensors and complex measurement systems, achieving performance optimization through a simple voltage measurement across the existing coil terminals.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The coil serves multiple functions: it acts as the electromagnetic actuator to drive the diaphragm and simultaneously as the sensor for measuring BEMF voltage to determine displacement. This multi-functionality reduces device complexity by eliminating separate components while achieving both actuation and measurement capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 allows synthetic jet actuators to operate at optimal performance and minimal energy consumption, preventing mechanical failures by dynamically adjusting diaphragm displacement based on real-time conditions.

Implementation Method 1

a coil which causes a diaphragm to vibrate about a first axis which is perpendicular to a major surface of the diaphragm

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

measuring the BEMF voltage across the coil; calculating the Back Electromotive Force BEMF, wherein BEMF=Vin−Iin*DCR

Methodology Applied

Scientific EffectBack Electromotive Force: Electromagnetic Induction

Data Source

PatentUS8290724B2Method and apparatus for controlling diaphragm displacement in synthetic jet actuators

Publication Date: 2012.10.16 NUVENTIX

AI summary

A method for calibrating a synthetic jet ejector is provided. The method includes (a) taking a first measurement DCR0 of the DC resistance of the coil; (b) adjusting the actuator drive voltage Vd to achieve a desired maximum displacement dmax1 at a frequency f1; (c) measuring the input current Iin and input voltage Vin; (d) calculating the back electromagnetic frequency BEMF, wherein BEMF=Vin−Iin*DCR; and (e) storing the calculated value of BEMF in a memory device associated with the synthetic jet actuator.