Engine Air-Fuel Ratio Control Learning Speed
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Solution Overview
Problem
Existing control systems for internal combustion engines face challenges in suitably changing the speed of updating the learning value when alternately switching the target air-fuel ratio between rich and lean air-fuel ratios, leading to potential delays in determination and excessive learning value acquisition.
Innovation Solution
A control system that alternately switches the target air-fuel ratio between rich and lean set air-fuel ratios, with conditions for learning acceleration, including adjusting the rich degree of the air-fuel ratio and the switching reference storage amount, to accelerate parameter correction based on oxygen cumulative values and maintenance times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the target air-fuel ratio is alternately switched between rich and lean air-fuel ratios, then the learning value can be updated, but the speed of updating the learning value cannot be suitably changed leading to delays in determination
Solution Approach 1:
The patent applies dynamics by making the rich degree of the air-fuel ratio adjustable rather than fixed. The control device changes the rich degree dynamically based on whether learning acceleration is required, allowing the system to adapt its behavior to different operational conditions and optimize both determination accuracy and speed.
Solution Approach 2:
The patent changes the parameter of air-fuel ratio composition (specifically the rich degree) to control the learning process. By adjusting the proportion of rich air-fuel ratio in the alternate switching cycle, the system can accelerate or decelerate learning value determination without compromising accuracy, directly addressing the time-loss problem.
2Productivity
If the ratio of obtaining the learning value is increased to speed up determination, then the speed of updating increases, but excessive learning value acquisition occurs
Solution Approach 1:
The patent implements feedback control where the control device continuously monitors whether learning acceleration is needed and adjusts the rich degree accordingly. This feedback mechanism prevents excessive learning value acquisition by reducing the rich degree when learning is sufficient, thereby maintaining determination accuracy while optimizing update speed.
Solution Approach 2:
The system dynamically adjusts the rich degree based on real-time learning status. When learning acceleration is required, the rich degree is increased to speed up determination; when learning is sufficient, the rich degree is reduced to prevent excessive acquisition, thus balancing productivity and reliability.
3Productivity
If the switching reference storage amount is increased, then the learning value can be updated more frequently, but the oxygen storage ability of the exhaust purification catalyst is compromised
Solution Approach 1:
The patent changes the parameter of switching reference storage amount dynamically. Instead of using a fixed high threshold that would compromise oxygen storage, the system adjusts this reference level based on learning acceleration needs and catalyst oxygen storage status, optimizing both update frequency and catalyst performance.
Solution Approach 2:
The control device uses feedback from the oxygen sensor to monitor catalyst oxygen storage ability and adjusts the switching reference storage amount accordingly. This ensures that learning value update frequency is increased only when it does not compromise the oxygen storage ability, maintaining reliability while improving productivity.
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
Enables the internal combustion engine to effectively and efficiently update the learning value, reducing delays and ensuring accurate determination, thereby suppressing NOX outflow and maintaining oxygen storage ability in the exhaust purification catalyst.
Implementation Method 1
an exhaust purification catalyst arranged in an exhaust passage of the internal combustion engine and capable of storing oxygen
Data Source
AI summary
The internal combustion engine comprises an exhaust purification catalyst able to store oxygen, and a downstream side air-fuel ratio sensor arranged at a downstream side of the exhaust purification catalyst in a direction of exhaust flow. The control system performs feedback control of an amount of fuel fed to a combustion chamber of the internal combustion engine so that an air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst becomes a target air-fuel ratio and performs learning control to correct a parameter relating to the feedback control based on an air-fuel ratio of exhaust gas detected by the downstream side air-fuel ratio sensor. The target air-fuel ratio is alternately switched between a rich set air-fuel ratio and a lean set air-fuel ratio leaner. When a condition for learning acceleration, which is satisfied when it is necessary to accelerate correction of the parameter by the learning control, is satisfied, a rich degree of the rich set air-fuel ratio is increased. Therefore, there is provided an internal combustion engine able to suitably change the speed of updating the learning value.