Exhaust Purification Intake Air Control for Torque Stability
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Solution Overview
Problem
The conventional exhaust gas purification systems using NOx storage reduction catalysts experience a decrease in engine torque due to the sudden reduction in intake air during the desulfurization process, leading to poor drivability and acceleration response.
Innovation Solution
An exhaust gas purification system with a desulfurization process control unit that gradually reduces the intake air amount by using a coefficient map to calculate a transitional target intake air amount, ensuring a smoother transition and minimizing the gap between target and actual intake air, thereby preventing sudden torque loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intake air amount is steeply reduced to achieve desulfurization process, then the NOx purification rate is maintained, but the engine torque decreases significantly
Solution Approach 1:
The patent applies dynamic control by introducing a transitional target intake air amount that varies over time during the desulfurization process. Instead of immediately stepping to the final target intake air amount, the system dynamically adjusts the intake air amount through intermediate stages, making the transition adaptive and continuous rather than abrupt
Solution Approach 2:
The patent performs preliminary action by pre-calculating and preparing a transitional target intake air amount before actually reducing the intake air. The control unit determines this transitional target in advance based on the desired final target intake air amount and current engine conditions, allowing for a planned and controlled reduction rather than an immediate sharp change
2Productivity
If the intake air amount is reduced instantaneously upon desulfurization commencement, then the desulfurization process starts efficiently, but the drivability deteriorates due to slow acceleration response
Solution Approach 1:
The system dynamically adjusts the intake air reduction process by using a transitional target that changes over time. The control unit continuously updates the transitional target intake air amount based on the current state, creating a dynamic transition path that balances desulfurization efficiency with maintaining acceptable drivability during the process
Solution Approach 2:
The patent segments the intake air reduction process into multiple stages: starting from the current intake air amount, transitioning through a transitional target intake air amount, and finally reaching the target intake air amount. This segmentation breaks down the abrupt change into manageable steps, reducing the impact on drivability while still achieving the desired desulfurization
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 suppresses engine torque decrease and improves drivability by gradually adjusting intake air during desulfurization, maintaining stable engine operation and preventing uncomfortable acceleration responses.
Implementation Method 1
sulfur dioxide in an exhaust gas, which is primarily derived from fuel, is absorbed by the LNT catalyst
Implementation Method 2
The desulfurization process brings the exhaust gas into a rich condition, i.e., a condition of low oxygen concentration, to remove sulfur dioxide, which is absorbed by the LNT catalyst
Implementation Method 3
the DPF regeneration process is usually carried out (i.e., PM collected by the DPF is burned and removed with the high temperature exhaust gas)
Data Source
AI summary
An exhaust gas purification system which can suppress a decrease in engine torque during a desulfurization process applied to a NOx storage reduction catalyst. The system includes a NOx storage reduction catalyst in an exhaust pipe of an engine, and a desulfurization process control unit that controls an amount of intake air introduced to the engine to enrich the exhaust gas, and performs a desulfurization process to the NOx storage reduction catalyst. The desulfurization process control unit is configured to gradually reduce an amount of intake air when the desulfurization process is commenced.