Fuel Filter Water Level Sensor Using Conductive Plastic

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Solution Overview

Problem

Existing fuel filter designs with metal pins for water level sensors are complex and costly due to the need for oxidation protection and sealing, which increases manufacturing expenses.

Innovation Solution

Replacing metal pins with electrically conductive plastic for the water level sensor poles and using electrically conductive plastic for the filter housing to form the second pole, eliminating the need for metal pins and their complex coatings, and using a two-component plastic injection molded design for insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal pins are used for water level sensor poles, then reliable electrical contact is achieved, but manufacturing complexity and cost increase due to oxidation protection and sealing requirements

Engineering Contradiction:
Improveelectrical contact reliabilityVSAvoidsensor structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces expensive metal pins with inexpensive plastic components that serve as water level sensor poles. The plastic material, while less conductive than metal, provides sufficient electrical contact for the sensor's function and eliminates the need for costly oxidation protection and sealing measures, directly addressing the contradiction between reliability and manufacturing complexity

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the material parameter from metal to plastic for the sensor poles. This material substitution fundamentally alters the electrical and mechanical properties, allowing the use of simpler manufacturing processes while maintaining adequate sensor functionality, thus resolving the contradiction between reliable electrical contact and manufacturing simplicity

Inventive Principle:
Principle #35Parameter changes

2Reliability

If metal pins with oxide coating are used, then oxidation resistance is improved, but manufacturing cost increases due to additional coating processes

Engineering Contradiction:
Improveoxidation resistanceVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent substitutes metal pins requiring expensive oxide coatings with inexpensive plastic components. The plastic material inherently resists oxidation without requiring additional protective layers, eliminating the need for costly coating processes while maintaining adequate durability for the sensor application

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent uses plastic as a composite alternative to metal, combining electrical conductivity (through carbon black or other additives) with oxidation resistance. This composite approach provides both required properties in a single material, eliminating the need for separate metal substrate and protective coating layers

Inventive Principle:
Principle #40Composite materials

3Measurement precision

If metal pins are used for water level detection, then effective water level sensing is achieved, but production expenses increase due to sealing and coating requirements

Engineering Contradiction:
Improvewater level detection accuracyVSAvoidproduction cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive metal pins with inexpensive plastic components for water level detection. The plastic poles maintain sufficient electrical conductivity (through carbon black or conductive fillers) to detect water levels accurately while eliminating the need for costly sealing and coating operations

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the material parameter from metal to plastic for the sensor poles, fundamentally altering the manufacturing approach. This substitution maintains adequate electrical conductivity for water level detection while eliminating the need for expensive protective treatments, directly resolving the contradiction between measurement precision and production cost

Inventive Principle:
Principle #35Parameter changes

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 approach results in a more cost-effective and simpler manufacturing process for the fuel filter, reducing production costs while maintaining effective water level detection without the risk of short circuits.

Implementation Method 1

a first pole (6) which is formed of an electrically conductive plastic

Methodology Applied
Scientific EffectElectrical conductivity: Conduction (electrical)

Data Source

PatentEP3271044B1Fuel filter
Publication Date: 2020.05.06 MAHLE INT GMBH
  • EP3271044B1 patent drawingFigure 1~3

AI summary

The invention relates to a fuel filter (1) comprising a housing (2), a filter element (3) in the housing, a water collection chamber (4) for collecting water that separates from the fuel, and a water level sensor (5) for sensing a water level in the water collection chamber (4). The invention is characterized in that a first terminal (6) made of an electroconductive plastic material is formed on the water level sensor (5). This makes it possible to dispense with at least one of the expensive metal electrodes.