Capacitive Fuel Sensor for Flexible Fuel Vehicles

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Solution Overview

Problem

Existing sensors for flexible fuel vehicles (FFVs) face challenges in durability and corrosion resistance when detecting fuel levels and concentrations, leading to inaccurate measurements and increased manufacturing costs, particularly when using alcohol-based fuels.

Innovation Solution

A multifunctional sensor is designed with a level sensor inserted into the pump module housing and a concentration sensor mounted on its side, both equipped with piezoelectric ceramics and dampers, ensuring durability and corrosion resistance, and integrated with a printed circuit board protected from ethanol fuel, allowing for precise ethanol content measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a contact sensor using a float arm is used to detect fuel level, then the sensor structure is simple and manufacturing cost is low, but the sensor board and contact point corrode when fuel containing alcohol is used

Engineering Contradiction:

Improvemanufacturing costVSAvoidcorrosion resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces the mechanical contact sensor system with a capacitive sensor system. The capacitive sensor detects fuel level through changes in capacitance caused by the dielectric properties of fuel, eliminating mechanical contact between the sensor and alcohol-containing fuel. This substitution resolves the corrosion issue while maintaining manufacturing feasibility.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a capacitive sensing mechanism as an intermediary between the sensor and the fuel. Instead of direct mechanical contact, the sensor measures fuel level through electrical field interactions with the fuel, using the fuel's dielectric properties as a mediator. This prevents direct contact and subsequent corrosion of sensor components.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a Hall sensor is used to prevent contact with fuel, then corrosion and malfunction caused by alcohol fuel are prevented, but manufacturing costs increase compared to existing sensors

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the Hall sensor (magnetic field-based) with a capacitive sensor system. The capacitive sensor uses electrical field interactions to detect fuel level and concentration, achieving similar non-contact measurement without the complexity and cost of Hall sensor implementation. This substitution maintains corrosion resistance while reducing manufacturing costs.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from magnetic field (Hall sensor) to electrical capacitance. By measuring changes in capacitance caused by the dielectric properties of fuel, the system achieves fuel level and concentration detection with simpler, less expensive components while maintaining reliability in alcohol-containing fuel environments.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If ultrasonic transceiver is used to measure liquid level, then non-contact measurement is achieved, but two electrodes need to be formed on the ultrasonic element and measurement accuracy decreases when fluid greatly sloshes and slopes

Engineering Contradiction:

ImprovedurabilityVSAvoidliquid level measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces the ultrasonic transceiver system with a capacitive sensor system. The capacitive sensor directly measures fuel level through capacitance changes without requiring ultrasonic elements or electrodes on the transducer surface. This elimination of complex ultrasonic components removes the requirement for two electrodes and improves measurement accuracy by being less sensitive to fluid sloshing and sloping conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 sensor provides excellent level detection performance, real-time concentration measurement, and reduced manufacturing costs while ensuring durability and corrosion resistance, enabling optimal engine combustion in FFVs.

Implementation Method 1

both equipped with piezoelectric ceramics

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

both equipped with piezoelectric ceramics and dampers

Methodology Applied

Scientific EffectDamping: Damping

Data Source

PatentUS10641640B2Fuel sensor for flexible fuel vehicle

Publication Date: 2020.05.05 HYUNDAI MOTOR CO LTD

AI summary

A sensor detects a fuel level and fuel concentration in a fuel tank of a flexible fuel vehicle (FFV) that uses flexible fuel such as ethanol fuel or alcohol fuel. The fuel sensor includes: a level sensor which is inserted into a lower surface of a pump module housing; and a concentration sensor which is mounted on a side surface of the pump module housing.