Liquid Level Sensor Conductive Segments Anti-Corrosion
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Solution Overview
Problem
Existing liquid level detecting devices for fuel tanks, particularly those using silver-based conductive segments, suffer from deterioration and corrosion due to sulfur content and moisture, leading to measurement failures and increased costs when using fuels like ethanol or gasoline, as they require high gold content for adequate protection.
Innovation Solution
The device employs conductive segments formed from a combination of silver (Ag) and palladium (Pd) as the primary material and gold (Au) as the secondary material, with the contact points made of gold to prevent corrosion and oxidation, reducing the overall gold usage and maintaining conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver-based conductive segments are used, then conductivity is improved, but deterioration and corrosion occur due to sulfur content and moisture
Solution Approach 1:
The conductive segment uses a composite structure with a silver base material and a gold plating layer. The silver provides high conductivity while the gold plating layer protects against sulfur content and moisture, preventing deterioration and corrosion. This composite material approach resolves the contradiction between maintaining conductivity and preventing harmful effects.
Solution Approach 2:
The gold plating layer acts as an intermediary between the silver conductive segment and the fuel environment. It serves as a protective barrier that prevents direct contact between the silver and harmful substances like sulfur and moisture, while still allowing the electrical function to operate effectively.
2Object-affected harmful factors
If high gold content is used to prevent corrosion, then anti-corrosion protection is improved, but manufacturing cost increases
Solution Approach 1:
Instead of using high gold content throughout the entire conductive segment, the gold plating is applied only as a thin surface layer where it is most needed - at the interface with the fuel environment. This local application of gold provides maximum anti-corrosion protection with minimum gold usage, significantly reducing manufacturing costs while maintaining effective protection.
Solution Approach 2:
The composite structure of silver base material with gold plating allows the system to achieve high anti-corrosion performance through the protective gold layer while the bulk of the conductive segment remains the less expensive silver material, thus reducing overall manufacturing cost.
3Reliability
If silver-palladium alloy is used, then conductivity is maintained, but corrosion resistance against sulfur content is insufficient
Solution Approach 1:
The silver-palladium alloy provides the conductive base with improved mechanical properties, while the additional gold plating layer specifically addresses the corrosion resistance issue against sulfur content. The combination of silver-palladium alloy with gold plating creates a multi-layer composite that simultaneously achieves both good conductivity and enhanced corrosion resistance.
Solution Approach 2:
The gold plating layer serves as an intermediary protective barrier between the silver-palladium alloy and the sulfur-containing fuel environment, preventing sulfur from reaching and corroding the alloy material while allowing the electrical conductivity function to operate.
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 provides effective anti-corrosion and anti-deterioration protection for the liquid level detecting device, even with fuels containing sulfur, while minimizing gold usage and lowering manufacturing costs by ensuring adequate conductivity and preventing contact failures.
Implementation Method 1
a float 10 capable of floating at a liquid level by a buoyant force of a liquid
Implementation Method 2
The first conductive pattern 15 is formed of a plurality of conductive segments 15a which are arranged in the circumferential direction of the arc shape at a predetermined interval and a resistor 15b which mutually and electrically connects the plurality of conductive segments 15a
Data Source
AI summary
A liquid level detecting device includes a resistor plate having conductive segments, a float that vertically moves in accordance with a displacement of a liquid level, a float arm that has one end to which the float is attached and the other end which is rotatably supported so as to be rotated in association with a vertical movement of the float, and a contact point that slides on the conductive segments in association with a rotation of the float arm. Each of the conductive segments is formed of a first metallic material and a second metallic material. The first metallic material has silver (Ag) and palladium (Pd) and the second metallic material has gold (Au) as a main component. A part which is to be brought into contact with the contact point in each of the conductive segments is formed of the second metallic material.