Exhaust Purification System Lean-Rich Transition Control
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Solution Overview
Problem
The existing NOx and SOx purge methods in exhaust purification systems, relying solely on fuel injection, lead to excessive fuel consumption and unstable engine combustion due to rapid injection timing advances, causing drivability issues and torque fluctuations.
Innovation Solution
An exhaust purification system that combines air-system control and injection control to manage the intake air amount and exhaust gas state, using a combination of SOx and NOx purge controls to adjust the air-fuel ratio and catalyst temperature, allowing for a more gradual transition between lean and rich states, thereby stabilizing combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only fuel injection control is used for NOx and SOx purge, then the purge function is achieved, but fuel consumption excessively increases
Solution Approach 1:
The patent combines air-system control (intake throttle valve or EGR valve adjustment) with injection control (post injection or exhaust pipe injection) to achieve purge functionality. This merging of two control systems allows the engine to transition between lean and rich states more efficiently, reducing the fuel consumption penalty associated with purge operations while maintaining the necessary NOx and SOx purification functions.
2Speed
If injection timing is advanced rapidly to achieve rich state, then the air-fuel ratio changes quickly, but combustion becomes unstable causing drivability deterioration
Solution Approach 1:
The patent implements dynamic coordination between air-system control and injection control, where the injection timing advance is synchronized with the air system response. This dynamic adjustment ensures that the injection timing changes at an appropriate rate relative to the air-fuel ratio changes, preventing combustion instability while still achieving the necessary transition to rich state for effective purge operations.
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 effectively reduces fuel consumption and stabilizes engine combustion by ensuring a controlled transition between states, minimizing NOx generation and torque fluctuations, and maintaining efficient catalyst regeneration.
Implementation Method 1
an unburned fuel is supplied to an upstream-side oxidation catalyst by the post injection or the exhaust pipe injection to raise an exhaust temperature to an SOx desorption temperature
Implementation Method 2
When the exhaust gas is under a lean atmosphere, the NOx occlusion reduction type catalyst occludes the NOx contained in the exhaust gas
Implementation Method 3
When the exhaust gas is under a rich atmosphere, the NOx occlusion reduction type catalyst detoxifies the occluded NOx through reducing and purifying by hydrocarbon contained in the exhaust gas
Data Source
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AI summary
It effectively suppresses an unstable combustion of an engine at a time of start or end of catalyst regeneration. The exhaust purification system includes: an NOx reduction type catalyst (32) which is provided in an exhaust passage of an internal combustion engine; a intake air amount sensor (40) which detects a intake air amount of the internal combustion engine; and a controller (50) which executes a regeneration treatment that switches an exhaust air fuel ratio from a lean state to a rich state by using an air-system control to reduce the intake air amount and an injection-system control to increase a fuel injection amount, which are used in combination. The controller (50) changes at least one of a fuel injection timing and the fuel injection amount in the internal combustion engine (10) in response to a detection value of the intake air amount sensor (40) in at least one period of switching of: a period of switching the lean state where the regeneration treatment is started to the rich state and a period of switching the rich state where the regeneration treatment is ended to the lean state.