Dual-Sensor Humidifier Temperature Control

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Solution Overview

Problem

Current respiratory assistance device humidifiers face challenges in accurately controlling temperature to ensure both performance and safety, particularly due to the thermal conductivity properties of water and the risk of overheating components.

Innovation Solution

Implementing two temperature sensors - one in direct contact with the metal heating plate to measure water temperature and another in contact with the heating element but thermally insulated from the plate to measure the heating element's temperature - to control the heating element's current and prevent overheating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single temperature sensor is used in contact with the metal heating plate, then the device structure is simple, but the temperature control precision is insufficient because it cannot distinguish between heating element temperature and water temperature

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the temperature measurement function into two separate sensors: a first temperature sensor in contact with the metal heating plate to measure plate temperature, and a second temperature sensor in contact with the heating element to measure heating element temperature. This segmentation allows independent measurement of each component's temperature, resolving the contradiction between measurement precision and device complexity by making the dual-sensor system a standardized integrated unit.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the heating element temperature is not monitored separately, then the device structure is simpler, but the safety control is insufficient due to risk of overheating

Engineering Contradiction:
Improvesafety controlVSAvoidheating control system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements feedback control by using the second temperature sensor to continuously monitor heating element temperature and feed this information back to the control unit. The control unit adjusts the heating element's power consumption based on this feedback, maintaining temperature within safe limits and preventing overheating, thus improving reliability while managing complexity through automated control.

Inventive Principle:
Principle #23Feedback

3Productivity

If only water temperature is measured, then the control system is simpler, but the performance optimization is limited because heating element temperature cannot be optimized

Engineering Contradiction:
Improvehumidification efficiencyVSAvoidcontrol system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The control unit uses feedback from both temperature sensors to optimize humidification performance. By monitoring both the heating element temperature (second sensor) and water/plate temperature (first sensor), the system can dynamically adjust heating power to maintain optimal temperature differential, maximizing vaporization efficiency and humidification performance while managing complexity through integrated control algorithms.

Inventive Principle:
Principle #23Feedback

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 dual-sensor system ensures accurate temperature control, preventing overheating risks and maintaining performance by estimating water temperature and monitoring the heating element's temperature, thus ensuring safety and efficiency in humidification.

Implementation Method 1

such as a resistive track which dissipates heat when it is traversed by an electric current

Methodology Applied
Scientific EffectResistive heating: Joule Heating

Implementation Method 2

a metal plate making it possible to transmit the heat produced by the heating element to the heating metal plate of the reservoir

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

to heat the water to vaporize it and thus charge the air flow with water vapor in a way to moisten it

Methodology Applied
Scientific EffectVaporization: Evaporation

Implementation Method 4

a component acting as a thermal fuse, which cuts off the current flowing in the resistive track when the temperature exceeds a given threshold

Methodology Applied
Scientific EffectThermal protection: Thermal Insulation

Data Source

PatentEP3345646B1Humidifier for respiratory apparatus
Publication Date: 2019.05.29 AIR LIQUIDE MEDICAL
  • EP3345646B1 patent drawingFigure 1~2
  • EP3345646B1 patent drawingFigure 3~6
  • EP3345646B1 patent drawingFigure 4~5

AI summary

The invention relates to a humidifier (18) for a respiratory support device (19) comprising a housing (14) designed to contain a reservoir (1) of water to be heated, said housing (14) comprising a heating structure (7) arranged in the bottom (15) of said housing (14), said heating structure (7) comprising a first metal plate (6) and at least one heating element (10) arranged to transmit the heat produced by said at least one heating element (10) to said first metal plate (6), and a first temperature probe (12) in direct contact with the first metal plate (6). According to the invention, the housing (14) further comprises a second temperature probe (13) in contact or near-contact with the heating element (10) and thermally insulated from the first metal plate (6). The invention also relates to a respiratory support device (19), such as a medical ventilator, comprising such a humidifier (18).