Engine Exhaust Control Device for Sulfur Poisoning and PM Filter Regeneration
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Solution Overview
Problem
The existing engine systems face challenges in efficiently eliminating sulfur poisoning from NOx catalysts and removing fine particulate matter from PM filters due to high temperature conditions, which lead to occluding agent coagulation and hinder the reaction of sulfur components with reducing agents, resulting in reduced purification efficiency.
Innovation Solution
A control device for the engine system that switches between rich and lean air-fuel ratios to perform NOx catalyst regeneration control and PM filter regeneration control, limiting the NOx catalyst's exposure to high temperatures and ensuring efficient removal of sulfur components by initiating NOx catalyst regeneration only after significant PM filter regeneration, thereby preventing excessive temperature rises and coagulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PM filter regeneration control is prolonged or executed at higher temperatures, then fine particulate matter is effectively removed from the PM filter, but the occluding agent in the NOx catalyst coagulates and hinders the reaction of sulfur components with the reducing agent
Solution Approach 1:
The patent performs PM filter regeneration control before NOx catalyst regeneration control. By removing fine particulate matter first through post-injection combustion in the PM filter, the system prevents occluding agent coagulation from occurring during the high-temperature PM regeneration process, thereby preserving the NOx catalyst's ability to react sulfur components with reducing agents in subsequent operations.
Solution Approach 2:
The patent divides the regeneration process into two distinct sequential stages: first PM filter regeneration control to remove fine particulate matter, then NOx catalyst regeneration control to remove sulfur components. This segmentation prevents the overlapping of high-temperature conditions that would cause occluding agent coagulation and loss of sulfur component reactivity.
2Productivity
If NOx catalyst regeneration control is performed when fine particulate matter accumulates excessively, then sulfur components can be removed from the NOx catalyst, but the fine particulate matter combustion causes excessive temperature rise and accelerates occluding agent coagulation
Solution Approach 1:
The patent removes fine particulate matter from the PM filter before initiating NOx catalyst regeneration control. This preliminary PM removal reduces the fuel consumption during subsequent NOx catalyst regeneration, thereby limiting excessive temperature rises and preventing occluding agent coagulation that would hinder sulfur component removal efficiency.
3Productivity
If the air-fuel ratio is set to rich for NOx catalyst regeneration, then sulfur components are removed from the NOx catalyst, but the NOx storage capacity decreases due to sulfur poisoning
Solution Approach 1:
The patent removes fine particulate matter from the PM filter before performing NOx catalyst regeneration control. This preliminary action reduces the amount of fuel consumed during the rich-state NOx catalyst regeneration process, limiting temperature exposure and preventing occluding agent coagulation. As a result, the NOx catalyst maintains its ability to store and reduce NOx effectively even after sulfur component removal.
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 eliminates sulfur poisoning and efficiently removes fine particulate matter, maintaining the NOx catalyst's performance while reducing fuel consumption and preventing abnormal combustion, by limiting high temperature exposure and optimizing regeneration timing.
Implementation Method 1
an oxidation catalyst configured to oxidize unburned fuel in exhaust gas
Implementation Method 2
a NOx catalyst configured to store NOx in the exhaust gas introduced to the NOx catalyst
Implementation Method 3
a particulate matter (PM) filter configured to capture fine particulate matter within the exhaust gas
Implementation Method 4
an occluding agent carried by the NOx catalyst may coagulate and make it difficult for the sulfur components to react with the reducing agent
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An engine control device is provided, which includes an oxidation catalyst provided in an exhaust passage to oxidize unburned fuel within exhaust gas, a NOx catalyst provided integrally with or downstream of the oxidation catalyst, a PM filter provided in the exhaust passage downstream of the oxidation catalyst to capture fine particulate matter within the exhaust gas, a fuel injector, and a controller. When the particulate matter is accumulated by a given amount, the controller starts a PM filter regeneration control to remove the particulate matter, and after this control is started and when the accumulation amount decreases by a given amount, the controller starts a NOx catalyst regeneration control to switch between a first state in which an air-fuel ratio of the exhaust gas is a stoichiometric air-fuel ratio or less and a second state in which the air-fuel ratio is higher than the stoichiometric air-fuel ratio.