Exhaust Gas Particle Sensor With Exposed Connection Region
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Solution Overview
Problem
Conventional particle detection sensors in exhaust gas flows, such as those for soot particles in internal combustion engines, face issues with moisture accumulation and process-related difficulties like pinhole creation due to platinum supply lines and ceramic coatings.
Innovation Solution
The sensor design features separate supply lines connected to measuring electrodes with an exposed connection region, where the supply lines are covered by an electrically insulating material except at the connection point, minimizing moisture entry and eliminating the need for thick platinum structures, thus avoiding pinhole formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If supply lines are coated with ceramic layer for insulation, then electrical insulation is improved, but moisture accumulates in the region of platinum-containing supply lines
Solution Approach 1:
The supply line structure is segmented into distinct regions: an exposed connection region without ceramic coating and a covered region with ceramic insulation. This segmentation allows the connection region to remain moisture-free while maintaining electrical insulation elsewhere, resolving the contradiction between insulation and moisture accumulation.
Solution Approach 2:
Different regions of the supply line have different properties: the connection region has no ceramic coating (exposed) to prevent moisture trapping, while other regions have ceramic coating for electrical insulation. This local differentiation of properties resolves the contradiction by applying insulation only where needed without creating moisture accumulation zones.
2Reliability
If thick platinum structures are used for supply lines, then electrical conductivity is improved, but pinhole formation occurs during overprinting process
Solution Approach 1:
The connection region is extracted from the ceramic coating coverage, creating an exposed area where no overprinting occurs. This eliminates the cause of pinhole formation (overprinting thick platinum structures) while maintaining adequate electrical conductivity through the exposed supply line section.
Solution Approach 2:
Instead of coating the entire supply line including connection regions (conventional approach), the invention inverts the approach by leaving connection regions exposed and only coating other areas. This reversal eliminates pinhole formation during overprinting while maintaining necessary insulation and conductivity.
3Ease of manufacture
If connection region is covered with ceramic layer, then manufacturing simplicity is improved, but moisture entry increases and particle deposition occurs
Solution Approach 1:
The coating process is segmented to exclude the connection region from ceramic coverage. This requires additional manufacturing steps (masking or selective coating) but prevents moisture and particle accumulation in the connection region, resolving the contradiction between manufacturing simplicity and preventing harmful factor accumulation.
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 moisture accumulation and process-related issues, enhancing manufacturability and sensor performance by maintaining the ceramic insulation while preventing particle deposition and eliminating the need for overprinting, which can cause pinholes.
Implementation Method 1
The supply lines are covered by at least one second layer, made from an electrically insulating material, such that the second layer of an electrically insulating material leaves the connection region exposed
Implementation Method 2
The soot particles collect between the electrodes as a result of electrostatic forces and, over the course of time, form electrically conductive bridges between the electrodes
Implementation Method 3
After a certain period of time, the sensor is regenerated through intrinsic heating and the accumulated soot is combusted. This is achieved by way of an integrated heater
Data Source
AI summary
A sensor for detecting particles, in particular soot particles. The sensor comprises at least two measuring electrodes which are situated on a first layer made of an electrically insulating or conductive material, and at least two supply lines for the measuring electrodes. The supply lines are connected to the measuring electrodes respectively in a connection region. The supply lines are covered by at least one second layer made of an electrically insulating material such that the connection region is not covered by the second layer made of an electrically insulating material.