Engine Controller Scavenging Process for Catalyst Oxygen Storage
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Solution Overview
Problem
Existing internal combustion engine controllers face challenges in preventing unburned fuel from flowing downstream during the temperature increasing process, particularly when the oxygen storage amount of the catalyst is low, leading to inefficient regeneration of the aftertreatment device.
Innovation Solution
A controller that executes a scavenging process prior to the temperature increasing process, which involves stopping combustion in one cylinder and enriching the air-fuel ratio in another cylinder to provide excess oxygen, ensuring sufficient oxygen storage in the catalyst before the rich combustion process, thereby preventing unburned fuel from flowing downstream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the temperature increasing process is executed directly without a scavenging process, then the regeneration process can start quickly, but unburned fuel may flow downstream from the catalyst due to insufficient oxygen storage
Solution Approach 1:
The controller executes a scavenging process prior to the temperature increasing process to supply oxygen to the exhaust passage and increase the oxygen storage amount of the catalyst in advance. This preliminary action ensures that when the temperature increasing process starts, the catalyst has sufficient oxygen to oxidize unburned fuel, preventing it from flowing downstream while maintaining quick regeneration startup
2Reliability
If the oxygen storage amount of the catalyst is increased through a scavenging process, then unburned fuel can be prevented from flowing downstream, but the regeneration process takes longer to start
Solution Approach 1:
The controller determines the execution of the scavenging process based on the current oxygen storage amount of the catalyst. When the oxygen storage amount is below a threshold value, the scavenging process is executed to replenish oxygen. This periodic action based on actual oxygen levels ensures the catalyst has sufficient oxygen before the temperature increasing process without unnecessarily delaying regeneration when oxygen is already adequate
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 configuration effectively increases the oxygen storage in the catalyst, ensuring that unburned fuel is oxidized during the temperature increasing process, enhancing the regeneration efficiency of the aftertreatment device and preventing fuel from flowing downstream.
Implementation Method 1
the aftertreatment device includes a catalyst that stores oxygen
Implementation Method 2
supplying oxygen to an exhaust passage after unburned fuel is discharged to the exhaust passage
Data Source
AI summary
When an amount of PM trapped by a GPF is large and a request for regeneration is made, a CPU determines whether an execution condition for executing a temperature increasing process is satisfied. At a point in time t1, at which the execution condition is satisfied, the CPU executes a scavenging process to assign 1 to a condition satisfaction flag Ftr, cause the air-fuel ratio of air-fuel mixture in cylinders #1, #3, and #4 to be the stoichiometric air-fuel ratio, and stop a combustion operation in a cylinder #2. After a point in time t2, which is after a combustion cycle, the CPU executes a temperature increasing process. The temperature increasing process causes the air-fuel ratio of the air-fuel mixture in the cylinders #1, #3, and #4 to be richer than the stoichiometric air-fuel ratio, and stops the combustion operation in the cylinder #2.