Dual-Media Filter Element for Reverse Flow Particle Retention

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Solution Overview

Problem

Filter elements in systems that handle sensitive fluids, such as urea or fuel, face issues with contamination and particle detachment during reverse flow, which can damage pumps due to the freezing or flocculation of fluids at low temperatures and the subsequent flow through the filter element.

Innovation Solution

A filter element with a first surface filter medium and a second depth filter medium, where the first medium has a lower relative pressure loss than the second medium, preventing particles from detaching and reaching the pump during reverse flow by ensuring they are filtered out and retained, with the second medium primarily handling normal operation fluid flow and the first medium handling reverse flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single filter medium is used, then the filter element structure is simple, but particles can detach during reverse flow and damage the pump

Engineering Contradiction:

Improvefilter element structureVSAvoidpump protection

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The filter element is divided into two distinct filter media with different functions: a first filter medium for normal filtration and a second filter medium for reverse flow protection. This segmentation allows each medium to be optimized for its specific function, preventing particle detachment during reverse flow while maintaining structural simplicity through modular design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the filter element are assigned different filter media with specific properties. The first filter medium has properties optimized for normal forward flow filtration, while the second filter medium has properties optimized for reverse flow conditions. This local differentiation ensures that particles are retained during reverse flow without requiring the entire filter structure to be complex.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If the filter element is designed to be heatable to prevent freezing, then the fluid can be protected from freezing, but energy consumption increases and development costs rise

Engineering Contradiction:

Improvefluid freezing protectionVSAvoidenergy consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The invention converts the potentially harmful reverse flow condition into a beneficial self-cleaning mechanism. During reverse flow, the second filter medium prevents particle detachment while allowing fluid to pass through, effectively using the reverse flow itself to protect the system without requiring additional energy input for heating or anti-freeze additives.

Inventive Principle:

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

Solution Approach 2:

The filter element uses the natural reverse flow of fluid to activate its protective function. The second filter medium is specifically designed to engage during reverse flow conditions, allowing the system to protect itself automatically without external energy input or control systems.

Inventive Principle:

Principle #25Self-service

3Productivity

If a pump changes pumping direction to remove fluid during standstill, then the system can be emptied, but particles detach from the filter element and reach the pump

Engineering Contradiction:

Improvesystem emptying capabilityVSAvoidparticle detachment

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The second filter medium is pre-positioned and pre-configured within the filter element to specifically handle reverse flow conditions. Before reverse flow occurs, the second filter medium is already in place to prevent particle detachment, allowing the system to safely perform reverse flow operations to empty the system without risking pump damage.

Inventive Principle:

Principle #10Preliminary action

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

Prevents particle detachment and reduces the risk of pump damage by ensuring particles are filtered out and retained, allowing for efficient fluid return without contaminating the pump, while maintaining low energy consumption and cost-effectiveness.

Implementation Method 1

a first filter medium (2) and a second filter medium (3)... particles that are present in a fluid on the unfiltered side (4) are filtered out at the first filter medium (2) and/or at the second filter medium (3)

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Data Source

PatentUS11642612B2Filter element having two filter media

Publication Date: 2023.05.09 ROBERT BOSCH GMBH

AI summary

A filter element includes an unfiltered side via which a fluid is able to be introduced, and a filtered side via which fluid is able to be output, and first and second filter mediums that are situated between the unfiltered and filtered sides, where the first filter medium has a lower relative pressure loss than the second filter medium in a flow direction of the fluid from the filtered side to the unfiltered side.