Wet/Dry Vacuum Filter Cartridge with Hydrophobic-Hydrophilic Sections

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Solution Overview

Problem

Wet/dry vacuum cleaners face issues with liquid penetration into the suction unit due to increased flow resistance and negative pressure when using water-absorbing filters, and existing safety valves can fail to prevent liquid ingress, especially when combined with cooling air ducts.

Innovation Solution

A filter cartridge design featuring alternating hydrophobic and hydrophilic filter sections that maintain air permeability while allowing liquid passage, ensuring the float valve functions correctly and preventing liquid penetration into the suction unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a water-absorbing filter medium is used for the filter body, then the filter body absorbs liquid, but the flow resistance increases and liquid can be sucked into the suction unit

Engineering Contradiction:
Improveliquid preventionVSAvoidflow resistance
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The filter body is divided into multiple filter sections with different properties: hydrophobic sections that maintain air permeability and hydrophilic sections that allow liquid passage. This segmentation resolves the contradiction by preventing the entire filter from absorbing liquid while still managing moisture effectively.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the filter body are assigned different functional qualities - hydrophobic areas for maintaining air flow and hydrophilic areas for liquid management. This local differentiation allows the filter to prevent liquid ingress while maintaining low flow resistance for air suction.

Inventive Principle:
Principle #3Local quality

2Temperature

If a safety valve with cooling air duct is used, then the suction unit can be cooled, but liquid can penetrate into the suction unit through the open cooling duct

Engineering Contradiction:
Improvecooling functionVSAvoidliquid prevention
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The filter body serves multiple functions simultaneously: it filters air, manages liquid, and works with the safety valve system to prevent liquid ingress while allowing cooling air flow. The hydrophobic sections specifically enable cooling air passage while the overall filter structure maintains liquid prevention.

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

3Loss of energy

If a water-repellent filter medium is used, then air permeability is maintained, but liquid passage is blocked and float valve function is impaired

Engineering Contradiction:
Improveair permeabilityVSAvoidliquid passage
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The filter body is divided into hydrophobic sections for air permeability and hydrophilic sections for liquid passage. This segmentation allows the filter to maintain air flow while enabling liquid to reach the float valve, resolving the contradiction between water repellency and liquid passage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Specific regions of the filter are made hydrophilic to allow liquid passage to the float valve, while other regions remain hydrophobic to maintain air permeability. This local quality differentiation resolves the contradiction by providing both functions in appropriate locations.

Inventive Principle:
Principle #3Local quality

4Ease of manufacture

If the filter body is designed as a hollow-cylindrical filter cartridge, then it can be easily manufactured, but negative pressure can raise the liquid level and cause liquid penetration

Engineering Contradiction:
Improvefilter body structureVSAvoidliquid level control
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The hollow-cylindrical filter cartridge is divided into hydrophobic and hydrophilic sections. The hydrophilic sections allow liquid to pass through to the float valve, preventing liquid accumulation that would occur in a completely sealed hollow cylinder, while maintaining the easy-to-manufacture cylindrical structure.

Inventive Principle:
Principle #1Segmentation

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 cartridge ensures high air and water permeability, preventing liquid ingress into the suction unit while maintaining effective suction and float valve operation, even when wet, by using hydrophobic sections for air flow and hydrophilic sections for liquid passage.

Implementation Method 1

The suction air can flow through a water-repellent, i.e. hydrophobic, filter section

Methodology Applied
Scientific EffectHydrophobic effect: Hydrophobe

Implementation Method 2

liquid can flow through a water-attracting, i.e. hydrophilic, filter section

Methodology Applied
Scientific EffectHydrophilic effect: Hydrophile

Data Source

PatentEP2523590B1Vacuum cleaner filter
Publication Date: 2013.11.13 ALFRED KARCHER SE & CO KG
  • EP2523590B1 patent drawingFigure 1
  • EP2523590B1 patent drawingFigure 2~3
  • EP2523590B1 patent drawingFigure 4

AI summary

The invention relates to a vacuum cleaner filter (44/78) having a filter element (46) that can be fixed on a filter bracket (28, 38/54, 64) of a vacuum cleaner (10), and comprising a filter body (48) that can be permeated by the suction air drawn in by the suction unit (18) of the vacuum cleaner (10) for precipitating suction material. In order to further develop the vacuum cleaner filter (44/78) such that the filter body (48) comprises a high level of precipitation for suction material in a wet and a dry state, and is permeable to both water and air, the filter body (48) comprises at least one air-permeable hydrophobic filter section (71, 73/81) and at least one air-permeable hydrophilic filter section (72, 74/82) disposed in parallel with each other in the flow direction of the suction air. The invention further relates to the use of such a vacuum cleaner filter (44/78) in combination with a float valve (26/42) disposed downstream in a wet/dry vacuum cleaner (10).