Exhaust Gas Sensor Dynamic Monitoring via High-Pass Filtering
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Solution Overview
Problem
Existing methods for dynamic monitoring of gas sensors in internal combustion engines are inadequate for precise diagnosis, especially in detecting rise times and dynamic properties, and are not suitable for hybrid vehicles without idling phases, requiring high availability and robustness against disruptions with low complexity and application effort.
Innovation Solution
The method involves filtering the output signal of gas sensors with a high-pass filter to evaluate higher-frequency components during changes in gas state variables, allowing for passive monitoring without intervention in the engine's air or fuel system, using a model to compare dynamics and normalize energy components for accurate diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods for dynamic monitoring of gas sensors are used, then the monitoring can be implemented, but the diagnosis precision for detecting rise times and dynamic properties is insufficient
Solution Approach 1:
The patent segments the sensor signal into different frequency components using a high-pass filter. By separating the dynamic components (higher frequencies) from the steady-state components (lower frequencies), the method enables precise measurement of rise times and dynamic properties without being affected by baseline drift or slow variations, thereby improving diagnosis precision while maintaining monitoring reliability
Solution Approach 2:
The patent applies partial action by focusing only on the higher-frequency components of the sensor signal that are relevant for dynamic monitoring. Instead of analyzing the entire signal spectrum, the high-pass filter selectively extracts the dynamic portions containing rise time information, improving measurement precision for dynamic properties while avoiding interference from low-frequency noise
2Adaptability or versatility
If active monitoring methods are used to detect sensor dynamics, then dynamic properties can be monitored, but the complexity of the system increases and hybrid vehicles without idling phases cannot be monitored
Solution Approach 1:
The patent implements self-service by using the sensor's own output signal as the monitoring source. The high-pass filter processes the sensor signal itself to extract dynamic characteristics, eliminating the need for external test signals or additional monitoring sensors. This approach enables monitoring in hybrid vehicles without idling phases while keeping the system complexity low, as no additional actuators or test equipment are required
Solution Approach 2:
The patent creates a universal monitoring method that works across different vehicle types including hybrid vehicles without idling phases. The high-pass filter approach is applicable to various sensor locations (upstream and downstream of catalytic converters) and vehicle operating conditions, providing adaptability without increasing system complexity through multiple specialized monitoring systems
3Measurement precision
If the dynamics of the upstream exhaust gas sensor decrease due to contamination or aging, then the air-fuel ratio control precision deteriorates, but detecting this degradation requires complex monitoring
Solution Approach 1:
The patent applies partial action by focusing only on the higher-frequency components of the sensor signal that contain dynamic response information. The high-pass filter extracts these dynamic portions, enabling detection of sensor degradation through simple amplitude and frequency analysis of the filtered signal, rather than requiring complex multi-parameter monitoring systems
Solution Approach 2:
The patent replaces complex mechanical or electronic test systems with a simple signal processing approach. Instead of using external test equipment or complex monitoring hardware to detect sensor degradation, the method uses digital or analog high-pass filtering combined with threshold-based detection, significantly reducing system complexity while maintaining measurement precision
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 approach provides a uniform monitoring principle for both increases and decreases in gas concentration, ensuring high robustness and low complexity, meeting the requirements for hybrid vehicles and other engines by accurately diagnosing sensor dynamics and preventing false assessments of exhaust gas purification system performance.
Implementation Method 1
Filtering higher-frequency signal components from the output signal of the gas sensor in the event of a change in the gas state variable to be measured or in the gas concentration
Data Source
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Figure 3
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AI summary
The invention relates to a method and to a device for the dynamic monitoring of gas sensors of a combustion engine, wherein a dynamic diagnosis is carried out based on a comparison of a modeled signal and of a measured signal in the case of a change in the gas state parameters to be measured, and the measured signal is an actual value of an output signal of the gas sensor and the model signal is a model value. According to the invention, the output signal of the gas sensor is filtered by means of a high-pass filter and the higher-frequency signal parts are processed. By means of the method and the device for carrying out the method, a uniform monitoring principle for the increase and the decrease of a gas concentration can be provided, which makes do without any intervention in the air or fuel system of the combustion engine and which has a high robustness with respect to dysfunctions and is characterized by very low complexity and low application cost. Said monitoring principle can also be used particularly in vehicles without coasting phases and without idling, such as in hybrid vehicles.