Acoustic Valve Shutter Design for Humidity Reliability

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Solution Overview

Problem

Existing in-ear hearing devices with acoustic valves experience increased failure to respond to actuation signals in higher humidity conditions due to capillary forces exerted by trapped water films.

Innovation Solution

The acoustic valve features a shutter surface with a protruding structure of small width, minimizing the contact surface area with the seat member, and a recessed structure to control water droplet flow, reducing capillary forces and ensuring reliable operation even in humid conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the contact surface area between shutter member and seat member is increased, then the sealing performance is improved, but the capillary force from trapped water film increases causing the valve to stick

Engineering Contradiction:

Improvevalve switching reliabilityVSAvoidcapillary force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The shutter surface is designed with a protruding structure that creates a localized small contact area region. This local quality change allows the valve to maintain reliable switching by minimizing capillary force at the contact portion while the surrounding non-contact portion provides acoustic sealing when the valve is closed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The shutter surface is segmented into distinct contact portion and non-contact portion by the protruding structure. This segmentation separates the functions of mechanical contact (minimizing capillary force) and acoustic sealing (blocking sound passage) into different spatial regions of the same component.

Inventive Principle:

Principle #1Segmentation

2Force

If additional power is provided to the valve actuator, then the actuator can overcome capillary force, but the energy consumption increases

Engineering Contradiction:

Improveactuator forceVSAvoidenergy consumption

Core Design Contradiction:

ForceVSUse of energy by moving object

Solution Approach 1:

The design converts the harmful effect of water condensation into a beneficial geometric feature. The protruding structure on the shutter surface is specifically designed to minimize contact area, thereby reducing capillary force from trapped water films. This allows the existing low-power actuator to overcome the reduced capillary force without requiring additional power, while still achieving reliable valve switching in humid conditions.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the width of the protruding structure is increased, then the contact surface area increases improving sealing, but the capillary force increases causing sticking

Engineering Contradiction:

Improveacoustic sealingVSAvoidcapillary force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The protruding structure creates an asymmetric shutter surface geometry where the contact portion has a deliberately small width compared to the overall shutter surface. This asymmetric design optimizes the balance between maintaining acoustic sealing (through the extended shutter surface) and minimizing capillary force (through the narrow contact portion with the seat member).

Inventive Principle:

Principle #4Asymmetry

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 effectively minimizes capillary forces, allowing the valve actuator to overcome these forces without additional power, ensuring reliable switching between open and closed states in humid environments.

Implementation Method 1

water molecules will exert boundary tension on these surfaces. The water film will act as a liquid bridge, generating an effective force—referred to as 'capillary force'—between the touching surfaces

Methodology Applied

Scientific EffectCapillary force: Capillary Action

Implementation Method 2

water vapour may condense onto those portions of the hearing device that are at a lower temperature than the ambient air

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentUS12279094B2Acoustic valve, and hearing device including such an acoustic valve

Publication Date: 2025.04.15 SONION NEDERLAND BV

AI summary

Acoustic valve for a hearing device, including a valve body defining a passageway, and a seat member and shutter member inside the valve body. The shutter member defines a shutter surface that forms a contact portion and a non-contact portion. The shutter member is moveable relative to the seat member to transition the valve between an opened state, wherein the shutter member is removed from the seat member and the passageway is open to allow sound to pass, and a closed state wherein the contact portion abuts the seat member and the non-contact portion blocks the passageway to restrict passage of sound. The contact portion forms a protruding structure that extends from the non-contact portion and towards the seat member, and has a small width along at least one transverse direction to minimise a contact area between the contact portion and the seat member when the valve is closed.