Adaptive Fuel Cut Restriction Temperature for Engine Catalyst
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Solution Overview
Problem
The intermittent execution of fuel cut in internal combustion engines due to catalyst temperature restrictions causes vibrations and noise, discomforting vehicle occupants, while also reducing the opportunities for diagnosing air/fuel ratio sensor abnormalities and potentially degrading catalyst performance.
Innovation Solution
A control apparatus and method that restricts fuel cut based on catalyst temperature, setting a lower fuel-cut-restriction temperature after completing the diagnosis of air/fuel ratio sensor abnormalities, allowing continuous fuel cut during catalyst temperature decrease, thus minimizing alternations between restriction and execution of fuel cut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel cut is prohibited when the catalyst temperature is high, then the catalyst performance is protected, but the diagnosis opportunities of air/fuel ratio sensor are reduced
Solution Approach 1:
The patent applies dynamics by making the fuel-cut-restriction temperature adaptive rather than fixed. The temperature threshold dynamically changes based on whether air/fuel ratio sensor diagnosis has been completed. When diagnosis is incomplete, a higher temperature threshold allows fuel cut at higher temperatures to preserve diagnosis opportunities. When diagnosis is complete, a lower threshold protects the catalyst. This dynamic adjustment resolves the contradiction between protecting catalyst performance and maintaining diagnosis opportunities.
2Reliability
If the fuel-cut-restriction temperature is lowered after diagnosis completion, then the catalyst is protected, but intermittent fuel cut execution causes vibrations and noise
Solution Approach 1:
The patent applies preliminary action by completing the air/fuel ratio sensor diagnosis before lowering the fuel-cut-restriction temperature. The system ensures diagnosis completion as a prerequisite for changing the temperature threshold to a protective level. This preliminary completion of diagnosis prevents subsequent intermittent fuel cut interruptions that would cause vibrations and noise, while still achieving catalyst protection through the lowered temperature threshold.
3Temperature
If the fuel cut is executed intermittently due to temperature fluctuations, then the catalyst temperature is maintained within safe limits, but the vehicle occupant experiences discomfort
Solution Approach 1:
The patent applies preliminary action by completing the air/fuel ratio sensor diagnosis before the fuel-cut-restriction temperature is lowered. This ensures that once the temperature threshold is set to a protective level, the diagnosis status will not change, preventing intermittent fuel cut execution even if catalyst temperature fluctuates. This eliminates vibrations and noise while maintaining catalyst temperature within safe limits through the established temperature threshold.
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 reduces the sense of strangeness caused by engine vibrations, maintains catalyst performance by minimizing high-temperature fuel cut occurrences, and ensures continuous diagnosis of air/fuel ratio sensor abnormalities without degrading catalysts.
Implementation Method 1
a catalyst configured to purify emission of the internal combustion engine
Data Source
AI summary
An engine ECU diagnoses the presence or absence of abnormality during execution of the fuel cut. The engine ECU is configured to restrict the fuel cut according to the temperature of a catalyst when the temperature is higher than a fuel-cut-restriction temperature of the catalyst. The engine ECU is configured to set the fuel-cut-restriction temperature is lower when the diagnosis has been completed than when the diagnosis has not been completed. Furthermore, the engine ECU continues the fuel cut if the diagnosis is completed during execution of the fuel cut while the temperature of the catalyst is between the fuel-cut-restriction temperature set prior to the completion of the diagnosis and the fuel-cut-restriction temperature set after the completion of the diagnosis.