Exhaust Gas Sensor Manipulation Detection in Overrun Fuel Cut
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Solution Overview
Problem
Existing methods are inadequate in reliably detecting manipulation of exhaust gas sensor values, particularly nitrogen oxide sensors, which can be tampered with to falsely indicate lower emissions, leading to inefficiencies in SCR systems and potential environmental harm.
Innovation Solution
A two-stage method involving overrun cut-off mode to detect initial suspicion of manipulation and a subsequent verification stage using threshold values and sensor gain checks to confirm manipulation, minimizing additional emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exhaust gas sensors are used to measure emissions, then emission control is improved, but sensor manipulation can occur leading to false readings
Solution Approach 1:
The patent performs preliminary actions by operating the engine in overrun cut-off mode before normal operation to establish a baseline sensor reading. This preliminary measurement in a known condition (throttle closed, no fuel injection) allows the system to detect deviations that indicate manipulation, thereby ensuring reliability before emission measurements are taken during normal operation.
Solution Approach 2:
The patent implements a feedback mechanism where the control unit continuously monitors sensor readings during overrun cut-off mode and compares them against expected values. When deviations are detected, the system provides feedback by setting manipulation suspicion flags and adjusting operational parameters, creating a closed-loop system that maintains measurement reliability through continuous verification.
2Reliability
If sensor manipulation detection methods are implemented, then detection reliability is improved, but additional emissions may be generated during verification
Solution Approach 1:
The patent employs periodic action by implementing manipulation detection during specific overrun cut-off events rather than continuous monitoring. The system periodically initiates detection sequences where the throttle is closed for predetermined periods, allowing manipulation suspicion to be assessed at intervals without requiring continuous high-emission operation, thus balancing detection reliability with emission minimization.
Solution Approach 2:
The patent utilizes parameter changes by transitioning the engine between different operational states (overrun cut-off mode with throttle closed versus normal operation). By changing the operational parameters temporarily for detection purposes and then returning to normal operation, the system achieves reliable manipulation detection while minimizing the duration and impact of additional emissions generated during verification processes.
3Difficulty of detecting and measuring
If throttle valve is closed for manipulation detection, then detection capability is improved, but engine operation is restricted
Solution Approach 1:
The patent applies dynamics by making the throttle valve position adaptive rather than fixed. The control unit dynamically adjusts the throttle position based on operational conditions and detection requirements, closing it temporarily during overrun events for manipulation detection and opening it during normal operation. This dynamic approach allows the system to optimize between detection capability and operational flexibility according to real-time needs.
Solution Approach 2:
The patent implements periodic action by closing the throttle valve at specific intervals during overrun events rather than maintaining a fixed closed position. This periodic closing allows manipulation detection to be performed at appropriate moments while maintaining engine operational flexibility during normal driving conditions, resolving the contradiction between detection capability and ease of operation.
Data Source
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AI summary
In a method for detecting manipulation of a sensor value of an exhaust gas sensor of an internal combustion engine for a vehicle, the internal combustion engine (1) is first operated in an overrun fuel cut mode. A first sensor value (ΔNox) of the exhaust gas sensor (70) is determined while a throttle valve (30) is closed. A suspicion of manipulation is established by evaluating the first sensor value (ΔNox) according to a first threshold value (C1). The suspicion of manipulation is verified by measuring a second sensor value (Nox(t2'), NH3(t2'), Nox(t3'), NH3(t3')) of the exhaust gas sensor (70) with an emission increase of the internal combustion engine (1) and by evaluating the second sensor value (Nox(t2'), NH3(t2'), Nox(t3'), NH3(t3')) according to a second threshold value (C2), if the suspicion of manipulation has been previously established.