Railcar Roof Air Conditioner UV Shielding for Heat Exchanger Hygiene

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Solution Overview

Problem

Existing air conditioning systems for railway vehicles fail to effectively disinfect surfaces within the air conditioning system, particularly the heat exchanger, where bacteria and viruses tend to adhere, and there is a need for a safer method to maintain hygiene.

Innovation Solution

An air conditioning system for railway vehicles that incorporates a heat exchanger and an ultraviolet-ray irradiation device, arranged between an upper cover and a bottom plate, with ultraviolet rays directed towards the heat exchanger surfaces to disinfect and embrittle adhering dust and bacteria, while preventing direct ultraviolet ray leakage into the vehicle using a grill and reflection surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ultraviolet-ray irradiation device is installed to disinfect heat exchanger surfaces, then hygiene effectiveness is improved, but risk of ultraviolet ray leakage into vehicle increases

Engineering Contradiction:
Improvehygiene effectivenessVSAvoidultraviolet ray leakage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a reflective plate as an intermediary element positioned between the ultraviolet-ray irradiation device and the vehicle interior. This reflective plate redirects ultraviolet rays toward the heat exchanger surfaces for disinfection while preventing direct leakage into the vehicle, thus resolving the contradiction between hygiene effectiveness and safety

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent extracts the ultraviolet-ray irradiation function from the main air conditioning system by installing it as a separate, dedicated device within the air conditioning unit. This separation allows the ultraviolet irradiation to be confined to specific areas (heat exchanger surfaces) without exposing the entire vehicle interior to ultraviolet radiation

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If ultraviolet rays are directed at heat exchanger surfaces, then disinfection capability is improved, but complexity of system arrangement increases

Engineering Contradiction:
Improvedisinfection capabilityVSAvoidsystem arrangement complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the ultraviolet-ray irradiation device with the existing air conditioning system structure, installing it within the air conditioning unit alongside the heat exchanger. This integration reduces overall system complexity by utilizing existing space and structural elements rather than adding a completely separate disinfection system

Inventive Principle:
Principle #5Merging (Combining)

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 system effectively disinfects and maintains the hygiene of heat exchanger surfaces by using a safe method, ensuring passenger safety by preventing direct ultraviolet ray exposure and enhancing cleanliness perception.

Implementation Method 1

an ultraviolet-ray irradiation device, the heat exchanger and the ultraviolet-ray irradiation device being arranged between an upper cover curved in an upwardly protruding shape and a bottom plate. The heat exchanger has an air suction surface arranged so as to be irradiated with ultraviolet rays generated by the ultraviolet-ray irradiation device

Methodology Applied
Scientific EffectUltraviolet irradiation: Radiation

Data Source

PatentEP4282730B1Railroad car air conditioner
Publication Date: 2025.08.13 HITACHI LTD
  • EP4282730B1 patent drawingFigure 1
  • EP4282730B1 patent drawingFigure 2
  • EP4282730B1 patent drawingFigure 3

AI summary

Provided is an air conditioning system for a railway vehicle that is of a roof installation type. The air conditioning system includes a heat exchanger through which at least air inside the railway vehicle passes, and an ultraviolet-ray irradiation device. The heat exchanger and the ultraviolet-ray irradiation device are arranged between an upper cover curved in an upwardly protruding shape and a bottom plate. The heat exchanger has an air suction surface arranged so as to be irradiated with ultraviolet rays generated by the ultraviolet-ray irradiation device. A member that does not transmit the ultraviolet rays is arranged on a straight line interconnecting the ultraviolet-ray irradiation device and an interior space of the railway vehicle.