Fuel Level Sensor Comb Structure Reduces Material
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Solution Overview
Problem
Existing level sensors for fuel tanks, particularly those using silver-palladium conductor tracks, face issues with increased material consumption and termination effects due to the need for a thicker resistance layer covering overlapping conductor tracks, which is exacerbated by the use of more expensive gold-platinum-palladium mixtures for corrosive fuels like ethanol.
Innovation Solution
The conductor tracks are designed with two areas arranged at a distance from each other, forming a comb structure, eliminating vertical overlap and allowing for a thinner resistance layer, using a gold-platinum-palladium mixture only where necessary for corrosion resistance and a silver-palladium mixture elsewhere, with precise positioning to avoid material mismatch issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second area of the conductor track overlaps perpendicularly onto the first area to connect the two areas, then the conductor tracks are electrically connected, but the conductor tracks have greater height and require significantly more resistance layer material
Solution Approach 1:
The patent transitions from a three-dimensional perpendicular overlap to a two-dimensional planar arrangement. The first and second areas are positioned side-by-side in the same plane rather than stacking vertically, eliminating the height increase while maintaining electrical connection through the comb structure interlocking
2Reliability
If the second area overlaps onto the first area to ensure electrical connection, then the conductor tracks are connected, but the areas between conductor tracks absorb significantly more resistor paste
Solution Approach 1:
By arranging areas in the same plane rather than perpendicular stacking, the patent reduces the total surface area that requires resistance layer coverage. The comb structure allows electrical connection without creating additional vertical surfaces that would consume extra resistor paste
3Reliability
If gold-platinum-palladium mixture is used in the first area for corrosive fuel resistance, then corrosion resistance is improved, but production costs increase significantly
Solution Approach 1:
The patent applies different material qualities to different functional areas: the expensive gold-platinum-palladium mixture is used only in the first area where corrosion resistance is critical (exposed to fuel), while the cheaper silver-palladium mixture is used in the second area (covered by resistance layer), optimizing both performance and cost
Solution Approach 2:
The patent changes the material composition parameter based on the functional requirements of each area. By varying the noble metal content and composition across different regions of the conductor track, the patent achieves necessary corrosion protection while minimizing overall material cost
4Quantity of substance
If the two areas are arranged at a distance with comb structure engagement, then vertical overlap is eliminated and resistance layer thickness is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The comb structure creates an interlocking mechanical and electrical connection between the two areas. The interdigitated teeth and gaps provide inherent alignment guidance that compensates for positioning tolerances, allowing the structure to self-align during assembly while maintaining both electrical connectivity and mechanical stability
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 design reduces material consumption, minimizes termination effects, and provides cost-effective corrosion resistance for level sensors in fuel tanks with corrosive fuels by maintaining sensor accuracy and reliability while reducing production costs.
Implementation Method 1
the nobler material in the first area is a gold-platinum-palladium paste. This material is characterized by good corrosion resistance from fuels, even if they contain aggressive additives such as ethanol
Implementation Method 2
To produce the resistor network, the respective mixture for the conductor tracks is printed as a paste onto the substrate and then sintered
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The sensor has a substrate (4) with resistor network which has resistor layer (8) and strip conductors (9) arranged in juxtaposed manner. Each strip conductor vertical to the path of sliding contact, has primary region (9a) in the path of sliding contact, and secondary region (9b) beside the path of sliding contact. The primary and secondary regions having different materials, overlap with each other. The primary and secondary regions are spaced apart from each other with a spacing (16). The opposite ends (10a,10b) of the regions are engaged like a comb structure.