Particle Sensor Moisture Detection Method
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Solution Overview
Problem
Existing particle detection sensors in internal combustion engine exhaust systems are susceptible to moisture, leading to hydrothermal aging and unreliable detection of electrode drying, which can cause damage and short circuits.
Innovation Solution
A method for operating particle detection sensors that applies a second electrical voltage below the water decomposition voltage to detect moisture, preventing regeneration and measuring phases until the sensor is dry, and using protective heating to prevent further moisture accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor is regenerated by heating to at least 700°C to burn off soot deposits, then the particle detection function is restored, but moisture in the electrode area causes hydrothermal aging and sensor damage
Solution Approach 1:
The patent applies a second electrical voltage below the decomposition voltage for water (1.23 V) during a predetermined period outside the measurement phase to detect moisture presence before regeneration occurs. This preliminary detection prevents moisture-related damage during the subsequent high-temperature regeneration process by identifying when moisture is present and blocking the regeneration operation.
2Productivity
If a high electrical voltage is applied continuously to detect particles, then measurement is continuous, but moisture causes short circuits and electrode damage
Solution Approach 1:
The patent divides operation into measurement phases and predetermined periods outside measurement phases. During the predetermined period, a second electrical voltage below water decomposition voltage is applied to detect moisture. This periodic switching allows moisture detection without continuous high voltage application, preventing electrode damage while maintaining measurement capability during designated measurement phases.
3Adaptability or versatility
If the sensor operates in humid conditions, then the sensor remains functional for particle detection, but hydrothermal aging reduces sensor lifespan
Solution Approach 1:
The patent implements a feedback mechanism where the current and/or voltage measurement during the predetermined period provides information about moisture presence. Based on this feedback, the control unit decides whether to allow regeneration or switch to measurement phase, thereby preventing hydrothermal aging and extending sensor lifespan while maintaining operational adaptability.
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
Effectively detects moisture to prevent sensor damage, ensuring reliable operation and extending the lifespan of the sensor by avoiding regeneration during wet conditions and using low voltage to safely dry the sensor.
Implementation Method 1
Due to electrostatic forces, the soot particles are deposited between the electrodes and, over time, form electrically conductive bridges.
Implementation Method 2
The sensor element is periodically regenerated by heating it to at least 700°C using an integrated heating element, which burns off the soot deposits.
Implementation Method 3
This can be done, for example, by measuring the electrical resistance of the ceramic material separating the two electrodes. More precisely, the electric current flowing between the electrodes when an electrical voltage is applied is measured.
Implementation Method 4
a second electrical voltage is applied to the first electrode and the second electrode. The second electrical voltage is lower than the decomposition voltage for water (1.23 V). The presence of water on the sensor element is inferred if the current and/or voltage measurement, when the second electrical voltage is applied, yields a value that exceeds a threshold for an electric current.
Data Source
Figure 1~2
AI summary
The invention relates to a method for operating a sensor (10) for detecting particles, in particular soot particles, in a measurement gas, in particular in the exhaust gas of an internal combustion engine. The sensor (10) comprises a sensor element (12). The sensor element (12) comprises at least one electrically insulating element substrate (14), a first electrode (16) and a second electrode (18). The first electrode (16) and the second electrode (18) are arranged on the electrically insulating element (14). In the method, the first electrode (16) and the second electrode (18) carry out a current measurement and/or voltage measurement, wherein: the sensor (10) is operated in at least one measurement phase; during the measurement phase, a first voltage is applied to the first electrode (16) and the second electrode (18); during a predefined time period outside of the measurement phase, a second voltage is applied to the first electrode (16) and the second electrode (18); the second voltage is less than a decomposition voltage for water; the presence of water on the sensor element (12) is inferred if, while the second voltage is applied, the current measurement and/or voltage measurement results in a value that exceeds a threshold value for an electric current.