Expansion Membrane Assembly for Diesel Exhaust Fluid Filter Sealing

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Solution Overview

Problem

Liquid diesel exhaust fluid (DEF) expands by approximately 8% at temperatures of −11° C or less, posing challenges for filter assemblies in maintaining seals and preventing back pressure buildup, which existing designs struggle to address effectively.

Innovation Solution

An integrated expansion membrane assembly that forms multiple seals with the filter head and housing, extending along the inner, top, and outer surfaces of the housing to accommodate the expanded DEF volume, while also being lockable to prevent leakage, even under high pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional filter assembly uses a membrane and polyurethane foam to accommodate DEF expansion, then the filter assembly can handle volume expansion, but the sealing reliability deteriorates under high pressure and the structure becomes more complex

Engineering Contradiction:

Improveaccommodation of DEF volume expansionVSAvoidsealing reliability under high pressure

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs a flexible membrane that can expand and contract to accommodate DEF volume changes while maintaining sealing integrity. The membrane is designed to flex under pressure rather than rigidly resist it, allowing the system to adapt to expansion while preserving seal reliability.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The filter assembly is divided into distinct functional zones: a filtration section with the filter element, an expansion accommodation section with the flexible membrane, and a sealing section with dedicated sealing elements. This segmentation allows each component to optimize its specific function without compromising overall system reliability.

Inventive Principle:

Principle #1Segmentation

2Volume of stationary object

If a membrane and foam are used to separate DEF from the housing, then expansion space is provided, but the device complexity increases

Engineering Contradiction:

Improvevolume for DEF expansionVSAvoidnumber of components in filter assembly

Core Design Contradiction:

Volume of stationary objectVSDevice complexity

Solution Approach 1:

The patent combines the membrane and sealing elements into an integrated assembly that serves dual functions: accommodating expansion and maintaining seals. This merging reduces the number of separate components while preserving both expansion capacity and sealing reliability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The flexible membrane is designed to perform multiple functions simultaneously: it accommodates volume expansion, maintains fluid separation, and provides structural support for the sealing interface. This multi-functionality reduces overall device complexity by eliminating the need for separate dedicated components for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Stress or pressure

If air vent is used to prevent back pressure buildup, then pressure management is improved, but the sealing requirements become more stringent

Engineering Contradiction:

Improveback pressure managementVSAvoidsealing integrity at vent interface

Core Design Contradiction:

Stress or pressureVSReliability

Solution Approach 1:

The patent introduces a dedicated sealing element as an intermediary component between the air vent interface and the housing. This intermediary seal specifically addresses the sealing challenge at the vent interface, allowing pressure management functionality while maintaining sealing integrity through a specialized sealing solution.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 membrane assembly effectively counters DEF expansion, preventing leakage and back pressure buildup by forming secure seals and providing additional volume for expansion, thus protecting structural components and ensuring reliable operation under varying conditions.

Implementation Method 1

The membrane assembly fluidly separates and is positionable between the housing and the filter element

Methodology Applied

Scientific EffectFluid separation: Semipermeable Membrane

Implementation Method 2

DEF inherently expands in volume by approximately 8% when exposed to a temperature of approximately −11° C. or less

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11857901B2Expansion membrane assembly and filter head in exhaust fluid filter assembly

Publication Date: 2024.01.02 ATMUS FILTRATION IP INC

AI summary

A filter assembly comprises a housing, a filter element for filtering a fluid and positionable within the housing, and an expansion membrane assembly. The expansion membrane assembly fluidly separates and is positionable between the housing and the filter element. The membrane assembly extends along an inner surface, a top surface, and an outer surface of the housing.