Humidifier Tub Lining for Heat Transfer and Electrical Isolation

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Solution Overview

Problem

Existing humidifier tubs face challenges in achieving effective heat transfer while insulating the heating element from water, and accommodating thermal expansion, which affects efficiency and durability.

Innovation Solution

A tub design using a combination of two materials, where a stable, insulating first material forms the container and a biocompatible, thermally conductive second material lines the heating element and inner surfaces, providing electrical insulation and accommodating thermal expansion, and is molded over the heating element for enhanced sealing and manufacturing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single material is used for the container, then manufacturing is simple, but it cannot simultaneously provide thermal insulation and thermal conduction

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidenergy consumption
Core Design Contradiction:
Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The patent employs a composite structure consisting of an outer container made of thermally insulating material and an inner liner made of thermally conductive material. This composite approach allows the system to simultaneously achieve thermal insulation (reducing energy consumption) and thermal conduction (improving heat transfer efficiency) by combining materials with complementary thermal properties.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies different material properties to different regions of the container. The outer container uses thermally insulating material to reduce heat loss to the environment, while the inner liner uses thermally conductive material to efficiently transfer heat from the heating element to the liquid. This local differentiation of material quality optimizes both energy efficiency and heating performance.

Inventive Principle:
Principle #3Local quality

2Stability of the object's composition

If a rigid lining is used, then structural stability is improved, but thermal expansion stress cannot be accommodated

Engineering Contradiction:
Improvestructural stabilityVSAvoiddurability under thermal stress
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent employs a flexible or elastomeric liner material that can dynamically adapt to thermal expansion and contraction of the heating element and container. This dynamic property allows the lining to maintain structural integrity and sealing effectiveness across varying temperature conditions, preventing stress concentration and potential failure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent selects lining materials with specific elastomeric properties that allow controlled deformation under thermal stress. The material parameters (such as elastic modulus and thermal expansion coefficient) are chosen to accommodate the thermal cycling conditions, enabling the lining to flexibly respond to temperature changes while maintaining its functional integrity.

Inventive Principle:
Principle #35Parameter changes

3Power

If the heating element is directly exposed, then heat transfer is maximized, but electrical insulation from water is compromised

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidelectrical insulation
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a thermally conductive liner as an intermediary layer between the heating element and the water. This liner material serves as a mediator that provides electrical insulation (preventing short circuits) while maintaining efficient thermal conduction (transferring heat to the water), thus resolving the contradiction between safety and heating efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses composite material structure where the inner liner combines electrical insulating properties with thermal conduction properties. This composite approach allows the system to achieve both electrical safety (isolating the heating element from water) and thermal efficiency (effective heat transfer to the liquid being heated).

Inventive Principle:
Principle #40Composite materials

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 improves heat transfer efficiency, reduces energy consumption, and enhances durability by allowing for stress accommodation and improved sealing, making it cost-effective and suitable for various applications.

Implementation Method 1

The water in the water tub is typically heated via thermal conduction between the heating element and the tub base of the water tub

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

accommodate any stress caused by thermal expansion of, e.g., the heating element

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

The second material, on the other hand, may be chosen such as to provide a preferably elastic lining which is adapted to electrically insulate the supply of water from the heating element and at the same time accommodate any stress caused by thermal expansion

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 4

a heating element for heating the water in the tub

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3708213B1Heating apparatus
Publication Date: 2022.11.02 RESMED PTY LTD
  • EP3708213B1 patent drawingFigure 1~2
  • EP3708213B1 patent drawingFigure 3
  • EP3708213B1 patent drawingFigure 4

AI summary

The present technology relates to a tub for a humidifier comprising a container made of a first material, a heating element, and a lining made of a second, preferably biocompatible, material different from the first material, wherein the container comprises a base and a side wall defining a reservoir for a supply of liquid to be evaporated, the heating element is provided on the base of the container, and the lining covers the heating element and a substantial portion of the inner surface of the side wall of the container.