Heating Oil Filter with Return Switchover Valve

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Solution Overview

Problem

Existing fuel filter devices for heating oil suffer from air accumulation issues due to low pressure differences and limited filtration fineness, especially at small volume flows, leading to suboptimal performance and potential clogging.

Innovation Solution

Incorporating a return switchover valve that connects the return line to the supply line either upstream or downstream of the fuel filter, allowing for multiple filtration passes, which enhances filtration fineness and reduces air accumulation, and optionally including a non-return valve with pressure relief and a bypass valve for improved venting and drainage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If single-line filtration is used, then device complexity is reduced, but air accumulation occurs in the filter bowl

Engineering Contradiction:
Improvefiltration system complexityVSAvoidair accumulation
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent implements a dynamically switchable return line configuration using a two-position valve. The system can switch between connecting the return line upstream of the filter (multiple filtration mode) and downstream of the filter (single filtration mode), allowing adaptive optimization based on operating conditions to prevent air accumulation while managing system complexity

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters of the filtration system by enabling multiple passes through the filter element. By switching the return line connection point, the system increases the number of filtration cycles for the same fuel volume, thereby improving air removal efficiency without requiring a completely different system architecture

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If filter element surface is completely wetted with fuel, then filtration effectiveness is improved, but air bubbles cannot penetrate the liquid film

Engineering Contradiction:
Improvefiltration finenessVSAvoidair accumulation
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent employs periodic recirculation of fuel through the filter element via the return line. By continuously cycling fuel through multiple filtration passes, the system maintains effective wetting of the filter surface while periodically allowing air bubbles to be carried through the liquid film and vented, preventing accumulation

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent ensures continuous filtration action by routing the return line back to the supply line, creating a continuous loop where fuel undergoes multiple filtration passes. This continuous recirculation maintains the liquid film on the filter surface while consistently removing air bubbles through the vent, preventing accumulation over time

Inventive Principle:
Principle #20Continuity of useful action

3Manufacturing precision

If multiple filtration passes are implemented, then filtration fineness is improved to 5 µm, but pressure difference increases

Engineering Contradiction:
Improvefiltration finenessVSAvoidpressure difference
Core Design Contradiction:
Manufacturing precisionVSStress or pressure

Solution Approach 1:

The patent uses a dynamically switchable valve to adjust the number of filtration passes based on system requirements. When high filtration fineness is needed, the valve enables multiple passes through upstream return line connection. When pressure differential becomes excessive, the valve can switch to downstream connection for single-pass mode, dynamically balancing filtration quality and pressure constraints

Inventive Principle:
Principle #15Dynamics

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

This configuration significantly reduces air accumulation in the filter bowl, improves filtration fineness to 5 µm, and allows for adjustable flow rates, ensuring optimal filtering for both small and large consumers, while preventing overpressures and facilitating regular maintenance.

Implementation Method 1

a return switchover valve (14) which can be switched between two valve positions and which connects the return line (8) to the supply line (5) in one valve position upstream of the fuel filter (6) and in the other valve position downstream of the fuel filter (6)

Methodology Applied
Scientific EffectFluid flow control:

Implementation Method 2

a fuel filter (6) arranged in the flow line (5)

Methodology Applied
Scientific EffectPhysical filtration: Filter (physical)

Implementation Method 3

the feed line (5) between the tank connection (2) and the fuel filter (6) has a non-return valve (7) with integrated pressure relief

Methodology Applied
Scientific EffectPressure relief:

Implementation Method 4

A fuel vent is preferably arranged in the return line (8)

Methodology Applied
Scientific EffectVenting:

Data Source

PatentEP2446951B1Device for filtering and removing air from heating oil with return flow valve
Publication Date: 2012.10.10 AFRISO EURO INDEX MBH
  • EP2446951B1 patent drawingFigure 1a
  • EP2446951B1 patent drawingFigure 1b
  • EP2446951B1 patent drawingFigure 2

AI summary

In a device (1) for filtering and venting liquid fuel, in particular heating oil, which has a tank connection (2) for connecting to an oil tank, a supply connection (3) for connecting to an oil burner supply, a return connection (4) for connecting to an oil burner return, a supply line (5) connecting the tank connection (2) to the supply connection (3), an oil filter (6) arranged in the supply line (5) and a return line (8) connecting the return connection (4) to the supply line (5), according to the invention the return line (8) is connected to the supply line (5) by a return diverting valve (14) which can be switched between two valve positions, which connects the return line (9) upstream of the oil filter (6) in one valve position and downstream of the oil filter (6) in the other valve position.