Air sterilization device and air conditioning apparatus using same

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Solution Overview

Problem

Existing air sterilization systems face challenges in efficiently irradiating bacteria and viruses in air conditioners and purifiers due to low ultraviolet intensity and increased blowing resistance, particularly in rectangular ducts, where the ultraviolet light distribution angle and space constraints limit effective sterilization without increasing cost or resistance.

Innovation Solution

A rectangular frame with ultraviolet light emitting units and concave reflecting surfaces that reduce the light distribution angle and prevent ultraviolet light leakage, allowing for efficient reflection and increased ultraviolet intensity within a compact, thin design suitable for rectangular ducts, thereby enhancing sterilization efficacy while minimizing blowing resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If ultraviolet LEDs are mounted to increase ultraviolet intensity in the inactivation space, then the sterilization efficacy is improved, but the device complexity and cost increase

Engineering Contradiction:
Improveultraviolet intensityVSAvoiddevice complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

A reflecting mirror is introduced as an intermediary component to redirect and concentrate ultraviolet light from the LEDs onto the inactivation space. The mirror serves as a mediator that amplifies the ultraviolet intensity without requiring additional LED units, thereby achieving enhanced sterilization efficacy while controlling device complexity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The optical parameters of the system are changed by introducing a reflecting mirror with specific reflectivity characteristics. This changes the light distribution pattern and intensity in the inactivation space, allowing effective sterilization with fewer LEDs compared to a direct irradiation approach

Inventive Principle:
Principle #35Parameter changes

2Illumination intensity

If multiple ultraviolet LEDs and reflecting mirrors are used to increase ultraviolet intensity, then the sterilization efficacy is improved, but the blowing resistance increases

Engineering Contradiction:
Improveultraviolet intensityVSAvoidblowing resistance
Core Design Contradiction:
Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The solution transitions from a one-dimensional linear arrangement of LEDs to a two-dimensional spatial configuration by introducing reflecting mirrors that redirect light at different angles. This dimensional change allows ultraviolet irradiation from multiple directions, achieving comprehensive coverage and high intensity without requiring a long linear arrangement that would increase blowing resistance

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Volume of moving object

If the inactivation space is made short to reduce device size, then the apparatus size is reduced, but the ultraviolet exposure time decreases

Engineering Contradiction:
Improveapparatus sizeVSAvoidultraviolet exposure time
Core Design Contradiction:
Volume of moving objectVSDuration of action of moving object

Solution Approach 1:

The system uses periodic reflection of ultraviolet light between the LEDs and the reflecting mirror to create multiple passes of irradiation through the inactivation space. This periodic action allows the air to be exposed to ultraviolet light multiple times during a short residence time, effectively compensating for the reduced exposure time caused by the compact design

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The reflecting mirror ensures continuous ultraviolet irradiation by redirecting light that would otherwise escape back into the inactivation space. This continuity maintains high ultraviolet intensity throughout the short space, ensuring effective sterilization despite the reduced dimensions

Inventive Principle:
Principle #20Continuity of useful action

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 solution effectively irradiates dust, bacteria, and viruses in circulating air with ultraviolet light, preventing an increase in blowing resistance and maintaining a compact, cost-effective design suitable for rectangular ducts, ensuring thorough sterilization and reduced ultraviolet light leakage.

Implementation Method 1

an ultraviolet light emitting diode (hereinafter abbreviated as an ultraviolet LED) is used as a light source of the ultraviolet light that inactivates bacteria, viruses, and the like

Methodology Applied
Scientific EffectLight Emitting Diode: Light Emitting Diode

Implementation Method 2

first reflecting surfaces respectively provided on the pair of first opposite side portions so as to face each other, each first reflecting surface being concave such that a center thereof in the third direction bulges to outside of the ventilation space, the first reflecting surfaces being configured to reflect the ultraviolet light

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP4215219B1Air sterilization device and air conditioning apparatus using same
Publication Date: 2024.09.11 HITACHI LTD
  • EP4215219B1 patent drawingFigure 1
  • EP4215219B1 patent drawingFigure 2
  • EP4215219B1 patent drawingFigure 3

AI summary

There is provided an air sterilization apparatus that is excellent in applicability to a rectangular duct and can effectively irradiate dust, bacteria, viruses, and the like in circulating air with ultraviolet light while preventing an increase in blowing resistance. The air sterilization apparatus includes a rectangular frame, an ultraviolet light emitting unit, and first reflecting surfaces. The frame includes a pair of first opposite side portions spaced apart from each other in a first direction and extending along a second direction, and a pair of second opposite side portions spaced apart from each other in the second direction and extending along the first direction. A ventilation space is defined inside the frame. The ventilation space allows air to flow therethrough along a third direction substantially orthogonal to the first direction and the second direction. The ultraviolet light emitting unit is provided on at least one of the pair of first opposite side portions, and emits ultraviolet light toward the ventilation space. The first reflecting surfaces are respectively provided on the pair of first opposite side portions so as to face each other. Each first reflecting surface is concave such that a center thereof in the third direction bulges to the outside of the ventilation space. The first reflecting surfaces reflect the ultraviolet light. A length of the ventilation space in the third direction is shorter than a length of the ventilation space in the first direction and a length of the ventilation space in the second direction, and a shape of each first reflecting surface in any cross section perpendicular to the second direction is defined based on an arc having a radius of curvature equal to or larger than a distance between the pair of first reflecting surfaces.