Heat Pump Air Return Filtration to Prevent Filter Bypass

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Solution Overview

Problem

Existing heat pump devices in tumble dryers and washer-dryers face issues with air filtration, leading to contamination of heat exchangers due to bypasses in deep-bed filters, which reduce efficiency and make maintenance difficult.

Innovation Solution

A heat pump device with a second filter insert featuring a surface filter arranged downstream of the first filter insert, providing additional filtration and support to prevent bypasses and maintain filter stability, while allowing easy access for cleaning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a deep-bed filter is used to separate particles from process air, then filtration effectiveness is improved, but filter stability deteriorates due to bypasses forming over time

Engineering Contradiction:
Improvefiltration effectivenessVSAvoidfilter stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent combines a deep-bed filter and a surface filter into a dual-filter system. The deep-bed filter (first filter insert) handles particle separation while the surface filter (second filter insert) provides structural support and prevents bypasses. This merging of functions resolves the contradiction by maintaining both filtration effectiveness and filter stability simultaneously.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The surface filter serves multiple functions: it acts as a structural support element preventing bypasses, provides an additional filtration layer, and maintains the overall filter assembly stability. This multi-functionality allows the system to maintain high filtration effectiveness while ensuring long-term filter stability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Object-affected harmful factors

If filters are placed in the air return duct to protect heat exchangers, then heat exchanger contamination is reduced, but maintenance accessibility deteriorates

Engineering Contradiction:
Improveheat exchanger contaminationVSAvoidmaintenance accessibility
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The filter system is segmented into two separate removable filter inserts rather than a single fixed filter assembly. This segmentation allows each filter to be independently accessed and maintained through the inspection flap, improving maintenance accessibility while maintaining continuous protection for the heat exchanger.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The filter inserts are designed to be removable and replaceable through the inspection flap, transforming the static filter system into a dynamic one that can be easily accessed for maintenance. This dynamic design allows users to remove and clean or replace filters without disassembling the entire heat pump device.

Inventive Principle:
Principle #15Dynamics

3Object-affected harmful factors

If multiple filter inserts are used to improve filtration, then contamination prevention is improved, but device complexity increases

Engineering Contradiction:
Improvecontamination preventionVSAvoidfilter system complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The surface filter (second filter insert) serves dual purposes: it provides additional contamination prevention and acts as a structural support element for the deep-bed filter. This multi-functionality reduces the need for separate support structures, thereby limiting the increase in device complexity despite adding multiple filter inserts.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

Enhances air filtration, reduces contamination of heat exchangers, maintains filter stability, and simplifies maintenance by ensuring all air passes through the filters, thus improving the overall efficiency and accessibility of the heat pump.

Implementation Method 1

The surface filter is designed and arranged to support the first filter insert in sections from behind

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

A depth filter is used to separate particles such as dust, fine dust, detergent residues and other comparably smaller bodies from the moist process air

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 3

Inside the heat pump, the moisture extracted from the laundry is condensed from the process air in the evaporator

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 4

The process air absorbs moisture from the laundry and thereby dries it

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 5

The condenser and the evaporator are each in contact with the process air and with the refrigerant of the heat pump circuit in order to enable the exchange of thermal energy between them

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP3536847B1Heat pump apparatus
Publication Date: 2021.06.30 MIELE & CO KG
  • EP3536847B1 patent drawingFigure 1~2
  • EP3536847B1 patent drawingFigure 3~5
  • EP3536847B1 patent drawingFigure 6~7

AI summary

The invention relates to a heat pump device (1), preferably a household appliance (1), particularly preferably a clothes dryer (1) or a washer-dryer (1), with a rotatably mounted washing drum (11) for receiving laundry to be dried and with a process air circuit with a heat pump, wherein the process air circuit is configured to supply the washing drum (11) with dried process air from the heat pump via an air supply duct and to supply the heat pump with moist process air from the washing drum (11) via an air return duct (14), wherein a first filter element (2) is arranged in the air return duct (14) such that the moist process air can be filtered by the first filter element (2), wherein the first filter element (2) has at least one depth filter (21) and at least one second filter element (3) is arranged in the air return duct (14) downstream of the first filter element (2) in the flow direction of the process air.The heat pump device is characterized in that the second filter insert (3) has at least one surface filter (31) which is designed and arranged to support the first filter insert (2) section by section from behind.