Engine Controller Air-Fuel Ratio Control for Catalyst Temperature
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Solution Overview
Problem
Existing catalyst temperature-increasing control methods in spark-ignition internal combustion engines, which involve introducing unburned air-fuel mixtures to raise the temperature of three-way catalyst devices, often result in excessive temperature increases or delayed temperature rise due to improper air-fuel ratio management, leading to inefficient PM removal from filters.
Innovation Solution
A controller that dynamically adjusts the air-fuel ratio during catalyst temperature-increasing control by setting a richer air-fuel ratio initially and then switching to a leaner ratio, allowing for quick temperature increase while preventing excessive temperature rise, with the switching timing determined by the initial catalyst temperature and integrated fuel injection amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the fuel concentration of the air-fuel mixture introduced into the three-way catalyst device is excessively high, then the catalyst temperature increases quickly, but the catalyst temperature increases excessively
Solution Approach 1:
The patent applies periodic action by switching the air-fuel ratio between rich and lean conditions in a controlled sequence. The air-fuel ratio control unit switches from a rich air-fuel ratio to a lean air-fuel ratio at a switching timing during the catalyst temperature-increasing control, creating a periodic pattern of fuel injection that generates controlled temperature increases while preventing excessive temperature rise.
Solution Approach 2:
The patent applies dynamics by dynamically adjusting the air-fuel ratio based on the integration value of the fuel injection amount. The air-fuel ratio control unit determines the switching timing from the beginning of the catalyst temperature-increasing control based on the integrated fuel injection amount, making the system adaptive and dynamic rather than static, allowing optimal temperature control under varying conditions.
2Temperature
If the fuel concentration of the air-fuel mixture during the catalyst temperature-increasing control is reduced to limit an excessive increase in the catalyst temperature, then the catalyst temperature increases slowly, but it takes time to complete the catalyst temperature-increasing control
Solution Approach 1:
The patent uses periodic action with a specific pattern: initially introducing rich air-fuel mixture to quickly raise catalyst temperature, then switching to lean air-fuel mixture to maintain temperature without excessive increase. This periodic switching pattern optimizes both the speed of temperature increase and the total control time, resolving the contradiction between fast temperature rise and temperature control.
Solution Approach 2:
The patent applies preliminary action by determining the air-fuel ratio switching timing in advance based on the integration value of the fuel injection amount from the beginning of the catalyst temperature-increasing control. This pre-planned switching strategy ensures that the temperature increase is both rapid and controlled, preventing excessive temperature rise while completing the control process efficiently.
3Object-generated harmful factors
If unburned air-fuel mixture is introduced into the three-way catalyst device to increase catalyst temperature, then the PM deposited in the filter is burned and removed, but the air-fuel ratio management becomes complex
Solution Approach 1:
The patent applies feedback by using the integration value of the fuel injection amount as a control parameter to determine the air-fuel ratio switching timing. The air-fuel ratio control unit continuously monitors the integrated fuel injection amount and switches the air-fuel ratio at the appropriate timing, creating a feedback-based control system that simplifies the management of air-fuel ratio while maintaining effective PM removal.
Solution Approach 2:
The patent applies parameter changes by switching the air-fuel ratio parameter from rich to lean conditions during the catalyst temperature-increasing control. This parameter change strategy allows the system to achieve effective PM removal through controlled temperature increase while simplifying the control logic by using a clear parameter switching rule based on the integrated fuel injection amount.
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 enables efficient and controlled temperature increase of the three-way catalyst device, effectively burning and removing deposited PM from filters while preventing overheating, thus maintaining optimal engine performance.
Implementation Method 1
the unburned air-fuel mixture burns in the three-way catalyst device, thereby increasing the temperature of the three-way catalyst device
Implementation Method 2
When the heat of the high-temperature gas increases the temperature of the filter to be higher than or equal to the ignition point of the PM
Implementation Method 3
the PM deposited in the filter is burned and removed
Data Source
AI summary
A controller is configured to control an internal combustion engine. The controller is configured to execute a catalyst temperature-increasing control of increasing a temperature of the three-way catalyst device by introducing air-fuel mixture, which contains the fuel injected by a fuel injection valve, into an exhaust passage without burning the air-fuel mixture in a cylinder. The controller includes an air-fuel ratio control unit configured to control an air-fuel ratio of the air-fuel mixture during the execution of the catalyst temperature-increasing control such that the air-fuel ratio becomes a richer air-fuel ratio during a first period from a beginning of the catalyst temperature-increasing control to a specified air-fuel ratio switching timing than during a second period from the air-fuel ratio switching timing to a completion of the catalyst temperature-increasing control.