Exhaust Temperature Differential Detection for Missing Catalytic Devices
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Solution Overview
Problem
Diesel engine systems face challenges in detecting the presence or absence of catalytic devices, such as SCR and DPF, especially during transient operating conditions, which can lead to increased costs and potential engine warranty voidance due to tampering or theft, and poses risks of overheating and emission control failures.
Innovation Solution
An exhaust gas system with temperature sensors and an electronic control unit (ECU) that calculates temperature differences between inlet and outlet temperatures of the aftertreatment device, comparing these differences to predetermined thresholds to generate a fault signal if the catalytic device is missing or tampered with, thereby detecting its presence or absence during transient operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If catalytic devices (SCR, DPF) are installed in diesel engine systems, then emission control is improved, but the system becomes vulnerable to theft and tampering which increases costs and downtime
Solution Approach 1:
The patent implements a feedback mechanism by installing temperature sensors upstream and downstream of the catalytic device and using an ECU to continuously monitor temperature differences. When the catalytic device is removed or tampered with, the temperature differential changes, triggering a feedback signal to the ECU that activates a warning indicator or stores a diagnostic code, thereby detecting theft or tampering attempts.
Solution Approach 2:
The patent uses temperature sensors as intermediary elements to detect the presence or absence of the catalytic device. These sensors measure temperature at specific locations and provide indirect information about the catalytic device's status without requiring direct contact with the expensive catalytic components themselves.
2Reliability
If temperature sensors and ECU monitoring system are added to detect catalytic device presence, then theft and tampering detection is improved, but device complexity increases
Solution Approach 1:
The system utilizes the existing thermal energy from exhaust gases to perform the detection function. The catalytic device itself, by its presence or absence, creates the temperature differential that the sensors detect, meaning the system being protected helps create the detection signal, reducing the need for additional active components.
3Measurement precision
If detection system continuously monitors temperature during all operating conditions, then detection accuracy is improved, but energy consumption and false alarms during transient conditions increase
Solution Approach 1:
The patent implements dynamic monitoring by having the ECU evaluate temperature differential data in the context of current engine operating conditions. The system adapts its detection thresholds and evaluation criteria based on whether the engine is in steady-state or transient operation, thereby maintaining detection accuracy while reducing false alarms during transient conditions and optimizing energy consumption.
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
The system effectively reduces the risk of catalytic device tampering by accurately detecting missing or tampered catalytic devices, preventing engine damage and ensuring compliance with emission standards, thereby reducing downtime and costs associated with theft or improper modifications.
Implementation Method 1
An inlet temperature sensor senses exhaust gas temperature at an inlet of the aftertreatment device. An outlet temperature sensor senses exhaust gas temperature at an outlet of the aftertreatment device.
Implementation Method 2
Selective Catalytic Reduction systems (SCR) downstream of a Continuous Regeneration Trap (CRT), to limit or control emission of nitrogen oxides (NOx) into the atmosphere. An SCR downstream of the CRT may be used to further reduce NOx emissions. Housed within the canister is an Ammonia Oxidation Catalyst (AOC).
Implementation Method 3
The temperature sensors are used to determine when to inject diesel fuel to burn-off accumulated diesel soot on the DPF, commonly called dosing.
Data Source
AI summary
An engine includes an exhaust gas system which flows exhaust gasses through an aftertreatment device. A method is provided for detecting the aftertreatment device during a transient operating condition. The method includes sensing temperature of the exhaust gas at an inlet and at an outlet of exhaust aftertreatment system. The inlet temperature is filtered and an inlet temperature difference between the filtered and unfiltered inlet temperatures is calculated. If the absolute value of the inlet temperature difference is greater than the predetermined threshold, then an outlet temperature difference is calculated. If the absolute value of the outlet temperature difference is greater than the second threshold, then a fault signal is generated, indicating that an aftertreatment device is missing. The aftertreatment device includes an SCR catalyst and an ammonia oxidation catalyst.