Pulsed Non-Thermal Plasma Gas Sensor for Exhaust Monitoring
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Solution Overview
Problem
Existing gas monitoring systems for internal combustion engines face challenges such as high power consumption, electrode erosion, and lack of selectivity due to the use of constant voltage methods for detecting exhaust pollutants, which are also sensitive to temperature and water vapor.
Innovation Solution
A gas monitoring system employing a pulse generator to create non-thermal plasma between electrodes, using tuned voltage pulses to identify gas constituents by measuring current spikes, thereby reducing energy consumption and minimizing electrode erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If constant voltage is used to identify gas constituents, then gas constituent detection is achieved, but power consumption becomes high
Solution Approach 1:
The patent applies periodic pulsed voltage instead of constant voltage to create plasma. The voltage is applied in periodic pulses with specific width and amplitude, allowing gas constituent detection during the pulse periods while maintaining low power consumption during intervals between pulses. This periodic action resolves the contradiction by enabling detection functionality while significantly reducing overall power consumption compared to continuous constant voltage application.
2Measurement precision
If constant voltage is used to identify gas constituents, then gas constituent detection is achieved, but electrode erosion becomes severe
Solution Approach 1:
The patent uses periodic pulsed voltage application rather than constant voltage, creating plasma only during brief pulse intervals. This periodic action limits the duration of plasma exposure to electrodes, thereby reducing cumulative electrode erosion while still achieving adequate gas constituent detection during the pulse periods.
Solution Approach 2:
The patent employs narrow pulse widths (e.g., 1-10 microseconds) that rush through the plasma creation process quickly. This skipping approach creates plasma only for brief intervals sufficient for detection, then immediately stops voltage application, allowing electrodes to recover and minimizing erosion accumulation over time.
3Reliability
If high temperature is used for gas sensor operation, then sensor functionality is maintained, but sensitivity to water vapor and instability increase
Solution Approach 1:
The patent changes the operating temperature parameter from high (traditional semiconductor sensor operation) to low (near ambient temperature). By applying pulsed voltage to create non-thermal plasma, the system achieves sensor functionality without requiring high temperatures, thereby eliminating sensitivity to water vapor and improving stability while maintaining detection capability.
4Measurement precision
If ionization sensors operate at high voltage, then gas detection is achieved, but power consumption and device size increase
Solution Approach 1:
The patent applies voltage in periodic pulses with narrow width (1-10 microseconds) rather than continuous high voltage. This periodic action creates plasma only during brief intervals sufficient for ionization and detection, then stops voltage application, thereby achieving gas detection functionality while significantly reducing average power consumption compared to continuous high voltage operation.
Solution Approach 2:
The patent uses partial action by applying voltage only for the minimum necessary pulse width to create plasma and enable detection. The pulse duration is optimized to be just long enough to achieve ionization and measurement, but not excessively long, thereby minimizing power consumption while maintaining adequate detection capability.
Data Source
AI summary
A gas monitoring system is disclosed. The gas monitoring system may have a first electrode, a second electrode spaced apart from the first electrode to receive a gas between the first and second electrodes, and a pulse generator configured to apply a voltage pulse, tuned to a particular constituent of the gas, to the first and second electrodes and create a non-thermal plasma between the first and second electrodes. The gas monitoring system may also have a detection controller in communication with the pulse generator. The detection controller may be configured to determine an actual current between the first and second electrodes during application of the voltage pulse, and to determine a concentration of the constituent based on the actual current and an expected identity of the constituent.