Resistive Particle Sensor With Capacitive Integrity Check
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Solution Overview
Problem
Existing resistive particle sensors for detecting soot in internal combustion engine exhaust gas face challenges in determining sensor integrity due to conductive connections between conductor tracks, leading to unclear differentiation between soot presence and sensor integrity, and have low sensitivity due to short interaction areas between tracks.
Innovation Solution
The sensor employs meander-shaped conductor tracks connected via capacitance, allowing for separate contact surfaces and a capacitor to determine sensor integrity, with the capacitance value ranging from 50-800 pF, enabling clear differentiation and improved sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistor is provided to connect the conductor tracks for determining sensor integrity, then the sensor integrity can be determined, but if there is a quantity of particles between the conductor tracks resulting in conductive connection, it is no longer possible to clearly determine the integrity of the particle sensor
Solution Approach 1:
The patent introduces a capacitor as an intermediary element between the two conductor tracks. The capacitor blocks direct electrical conduction while allowing AC coupling, enabling integrity testing through capacitance measurements without the conductor tracks being directly conductive. This mediator resolves the conflict by providing a different measurement mechanism that isn't affected by particle-induced conduction between the tracks.
Solution Approach 2:
The patent replaces the resistive integrity check with a capacitive coupling measurement. Instead of measuring resistance through a resistor connection, the system measures the capacitance between the conductor tracks. This substitution changes the physical quantity being measured from electrical resistance to electrical capacitance, allowing integrity verification without the ambiguity caused by particle conduction.
2Device complexity
If the conductor tracks run in a straight line within the area exposed to exhaust gas, then the sensor structure is simple, but the interaction zone between the conductive traces is relatively short resulting in correspondingly low sensitivity
Solution Approach 1:
The patent applies meandering (curved) patterns to the conductor tracks instead of straight lines. The meander shape increases the length of the conductor tracks within the same sensor area, creating a longer interaction zone with the exhaust gas and particles. This curvature principle extends the effective detection path without increasing the physical footprint of the sensor element.
Solution Approach 2:
The meandering pattern transforms the one-dimensional straight-line arrangement into a two-dimensional space-filling pattern. By utilizing the available surface area more efficiently through curved paths and turns, the conductor tracks achieve greater length and interaction area within the same planar footprint, effectively adding dimensional utilization to compensate for the straight-line limitation.
3Measurement precision
If the conductor tracks are interconnected via a capacitor with value of 50-800 pF, then the integrity of the particle sensor can be determined and sensitivity is improved, but the device complexity increases
Solution Approach 1:
The capacitor serves multiple functions simultaneously: it enables integrity testing through capacitance measurements, provides the coupling mechanism for AC signals, and defines the sensitive interaction zone between conductor tracks. This multi-functionality reduces the need for separate components for each function, offsetting the added complexity by consolidating roles into a single element.
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 effectively determines sensor integrity and enhances sensitivity by utilizing meander-shaped conductor tracks connected via capacitance, allowing for accurate detection of soot particles while resolving the ambiguity between soot presence and sensor integrity.
Implementation Method 1
the conductive traces are electrically connected to one another via a capacitor (31) having a value of 50-800 pF
Implementation Method 2
a quantity of particles is sensed by means of electrical conductivity between the conductor tracks
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
The invention relates to a resistive particle sensor for detecting soot in the exhaust gas of an internal combustion engine, comprising a sensor element (113) with two conducting paths (25, 26) which run in a spaced manner in a sensor element (113) region that can be exposed to the exhaust gas in order to detect a particle quantity in a resistive manner. The conducting paths (25, 26) are connected together via a capacitor (30, 31), and the conducting paths (25, 26) run parallel to each other in meanders (252, 262) in the sensor element (113) region that can be exposed to the exhaust gas.