Fuel System Transfer Pump Pre-Filter Arrangement

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Solution Overview

Problem

Existing fuel systems for combustion engines are prone to operational disruptions due to impurities in the fuel, particularly in markets with poor fuel quality, and suffer from inadequate pre-filtration and increased clogging risks in filters.

Innovation Solution

A fuel system design that includes a pre-filter arranged downstream of a transfer pump driven by an electric engine in the low-pressure circuit, combined with a coarse mesh sieve in the second fuel tank, ensures that fuel is pre-filtered before reaching the main feed pump, reducing the risk of clogging and operational disruptions. This system uses a fine mesh water-separating filter and a valve for efficient fuel flow and control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pre-filter is arranged upstream of the main feed pump to pre-filter the fuel, then the fuel is filtered before reaching the pump, but the filter has an increased risk of clogging due to low pressure

Engineering Contradiction:
Improvefuel system reliabilityVSAvoidfilter clogging risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the conventional arrangement by placing the pre-filter downstream of the transfer pump instead of upstream. This reversal allows the filter to operate under positive pressure from the pump, eliminating the clogging risk associated with suction-side filtration while still providing effective fuel filtration before the main feed pump.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the pressure parameter at which the pre-filter operates. By locating the filter downstream of the transfer pump, the filtration process occurs under elevated pressure rather than low suction pressure, fundamentally altering the operating conditions to prevent clogging while maintaining filtration effectiveness.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If a coarse mesh sieve is used in the fuel tank to catch larger particles, then larger impurities are retained, but the sieve is not sufficient for adequate pre-filtration

Engineering Contradiction:
Improvesimple filtration structureVSAvoidfuel filtration effectiveness
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent implements a two-stage filtration system that segments the filtration process into coarse filtration (mesh sieve in the fuel tank) and fine pre-filtration (pre-filter downstream of transfer pump). This segmentation allows each filter to specialize in different particle sizes, with the coarse sieve handling large debris and the pre-filter providing thorough pre-filtration before the main feed pump.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by performing coarse filtration through the mesh sieve in the fuel tank before the fuel reaches the transfer pump, and then applying fine pre-filtration through the pre-filter downstream of the pump. This sequential preliminary filtration prepares the fuel in stages, ensuring both simplicity and effectiveness.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the transfer pump feeds fuel from the second fuel tank through the pre-filter to the first fuel tank, then the fuel is pre-filtered and pressurized, but the system complexity increases

Engineering Contradiction:
Improvefuel supply reliabilityVSAvoidfuel system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the transfer pump multi-functional by having it perform both the fuel transfer function (from second tank to first tank) and the pre-filtration function (through the pre-filter arranged downstream). This universality allows a single pump to accomplish multiple tasks, reducing overall system complexity while maintaining reliable fuel supply and filtration.

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

The solution effectively reduces the risk of operational disruptions and clogging in the fuel filter, providing better filtration than prior art by pressurizing the fuel through the pre-filter and using a dual filtration step, ensuring reliable fuel supply to the combustion engine.

Implementation Method 1

a pre-filter (30) arranged downstream of the transfer pump (28)

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

a coarse mesh sieve which is arranged inside the fuel tank... which catches and retains larger particles and impurities

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Data Source

PatentEP2976519B1Fuel system for combustion engine and a method for controlling a fuel system
Publication Date: 2019.05.08 SCANIA CV AB
  • EP2976519B1 patent drawingFigure 1~3
  • EP2976519B1 patent drawingFigure 2

AI summary

A fuel system (4) for a combustion engine (2) comprises a first fuel tank (20), a second fuel tank (22), a first fuel pipe (36) arranged in connection with the first fuel tank (20) and the second fuel tank (22), a second fuel pipe (40) arranged in connection with the first fuel tank (20), a main feed pump (26), and a trans¬ fer pump (28). The main feed pump (26) is arranged to feed fuel from the first fuel tank (20) through the second fuel pipe (40) and the transfer pump (28) is arranged to feed fuel from the second fuel tank (22) to the first fuel tank (20) via the first fuel pipe (36). A first electric engine (M1 ) is arranged to drive the transfer pump (28) and a second electric engine (M2) is arranged to drive the main feed pump (26). A pre-filter (30) is arranged downstream of the transfer pump (28), so that the transfer pump (28) feeds pressurised fuel through the pre-filter (30). The fuel system also enables a method to control a fuel system (4) with good filtration of the fuel, and which reduces the risk of operational disruptions in a combustion engine (2) and a motor vehicle.