Recyclable Granulate Filter Unit for Vehicle Interior NOx Reduction

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Solution Overview

Problem

Existing methods for reducing nitrogen oxide (NOx) emissions in vehicles and enclosed spaces are either temporary or require frequent filter replacement, and there is a lack of effective solutions for recycling used filters.

Innovation Solution

A filter unit with replaceable and recyclable adsorbent granules, such as zeolites or alkali oxides, that can be used in both supply and recirculation systems to continuously reduce NOx levels, with the option to recycle the granules and convert NOx into usable materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If recirculation setting is used to prevent outside air intake, then NOx emissions are reduced temporarily, but pollutants accumulate quickly and humidity rises rapidly

Engineering Contradiction:
ImproveNOx emissionsVSAvoidduration of air quality
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The system continuously adsorbs NOx onto the adsorbent material and periodically desorbs it by heating, recovering the accumulated pollutants for concentrated disposal rather than allowing continuous accumulation in the cabin air

Inventive Principle:
Principle #34Discarding and recovering

Solution Approach 2:

The system uses temperature-induced phase transitions of the adsorbent material to switch between adsorption mode (low temperature) and desorption mode (high temperature), enabling continuous operation without manual intervention

Inventive Principle:
Principle #36Phase transitions

2Object-affected harmful factors

If HEPA/activated carbon filters are used for filtering, then some filtering effect is achieved, but filter capacity is limited and must be replaced frequently

Engineering Contradiction:
Improvepollutant filtrationVSAvoidfilter replacement frequency
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

Instead of discarding saturated filters, the system recovers the adsorbed NOx by heating the adsorbent material, regenerates the adsorbent, and continues using it, eliminating the need for frequent replacements

Inventive Principle:
Principle #34Discarding and recovering

Solution Approach 2:

The system performs automatic regeneration of the adsorbent material through periodic heating cycles, making the filter self-maintaining without requiring manual replacement by the user

Inventive Principle:
Principle #25Self-service

3Object-affected harmful factors

If traditional filters are used without recycling capability, then NOx is removed from air, but the filter material cannot be recycled and must be disposed of

Engineering Contradiction:
ImproveNOx removalVSAvoidfilter material
Core Design Contradiction:
Object-affected harmful factorsVSLoss of substance

Solution Approach 1:

The system recovers both the adsorbent material and the adsorbed NOx through thermal desorption, converting what would be waste into recoverable resources for continued use or beneficial disposal

Inventive Principle:
Principle #34Discarding and recovering

Solution Approach 2:

The system converts the harmful accumulated NOx into a recoverable substance that can be concentrated and disposed of beneficially, while simultaneously regenerating the adsorbent material for continued service

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

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 filter unit achieves a permanent reduction in NOx concentration by allowing easy replacement and recycling of adsorbent granules, effectively maintaining clean air quality and providing a sustainable solution for NOx management.

Implementation Method 1

At least two granule chambers (6) are arranged between the pressure chambers (5), containing an adsorbent granulate capable of adsorbing nitrogen oxides

Methodology Applied
Scientific EffectAdsorption: Adsorption

Data Source

PatentEP4615614B1NOX reduction in a vehicle interior
Publication Date: 2026.03.25 AUDI AG
  • EP4615614B1 patent drawingFigure 1
  • EP4615614B1 patent drawingFigure 2~3

AI summary

The invention relates to a filter unit (1) for removing nitrogen oxides from air with a closed housing, which has a tube (4) at one end for introducing air into the filter unit (1) and a tube (2) at an opposing end for discharging air from the filter unit (1), wherein respective fans (3) are arranged in the tubes (2, 4), and wherein the tubes (2, 4) are each connected to a pressure chamber (5) in the housing, and at least two granulate chambers (6) are arranged between the pressure chambers (5), containing an adsorbing granulate capable of the adsorption of nitrogen oxides, and wherein the at least two granulate chambers (6) are separated from one another by an intermediate insert/filter insert (7).