Engine Stop Control for Catalyst Oxygen Management
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Solution Overview
Problem
Frequent starting and stopping of the engine in hybrid automobiles leads to an increase in oxygen concentration in the catalyst, exceeding its capacity to remove NOx, resulting in inadequate NOx removal and increased emissions.
Innovation Solution
A vehicle control system that includes an oxygen concentration detector and a processor to determine whether to prohibit engine stoppage based on oxygen concentration levels, ensuring the catalyst operates within optimal ranges by controlling the air-fuel ratio to maintain adequate oxygen levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is stopped frequently to save fuel, then fuel consumption is reduced, but oxygen concentration in the catalyst increases excessively
Solution Approach 1:
The control device continuously monitors oxygen concentration in the catalyst and uses this feedback to determine whether to stop or continue engine operation. When oxygen concentration exceeds a predetermined threshold, the engine is prohibited from stopping, creating a closed-loop control system that balances fuel economy with catalyst performance.
Solution Approach 2:
The system changes the operational parameter (engine stoppage decision) based on the measured oxygen concentration level. When oxygen concentration is below the threshold, normal stoppage operations are allowed; when it exceeds the threshold, the stoppage parameter is changed to prohibited, dynamically adjusting system behavior based on real-time conditions.
2Use of energy by moving object
If the engine is stopped frequently, then fuel economy improves, but NOx removal capability deteriorates
Solution Approach 1:
The control device uses oxygen concentration measurements as feedback to assess catalyst health and adjust engine operation accordingly. This feedback mechanism ensures that engine stoppages do not compromise the catalyst's ability to remove NOx, maintaining emission control reliability while pursuing fuel economy.
Solution Approach 2:
The system takes preliminary action by checking oxygen concentration before allowing engine stoppage. By anticipating the potential harm of excessive oxygen accumulation, the control device prevents stoppages that would compromise NOx removal capability, addressing the issue before it occurs rather than reacting after damage is done.
3Reliability
If the engine is prohibited from stopping when oxygen concentration is high, then catalyst performance is maintained, but fuel consumption increases
Solution Approach 1:
The system dynamically changes the engine stoppage parameter based on oxygen concentration levels. When oxygen concentration is below the threshold, the stoppage parameter is set to allowed (optimizing fuel consumption). When it exceeds the threshold, the parameter changes to prohibited (maintaining catalyst performance). This conditional parameter adjustment resolves the contradiction by adapting to real-time catalyst state.
Solution Approach 2:
The control strategy transitions from a static, fixed stoppage schedule to a dynamic, condition-based decision system. The engine stoppage behavior becomes flexible and adaptive, changing in real-time based on oxygen concentration measurements, thereby optimizing the balance between fuel consumption and catalyst performance under varying operating conditions.
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
Prevents excessive oxygen concentration in the catalyst, allowing it to effectively remove NOx, thereby reducing NOx emissions and ensuring the catalyst's adequate functioning.
Implementation Method 1
an oxygen concentration detector configured to measure oxygen concentration in the catalyst
Implementation Method 2
a catalyst configured to clean gas emitted from the engine
Data Source
AI summary
A vehicle includes an engine, a catalyst, an oxygen concentration detector, and a control device. The catalyst is configured to clean gas emitted from the engine. The oxygen concentration detector is configured to measure oxygen concentration in the catalyst. The control device includes at least one processor and at least one memory coupled to the at least one processor. The at least one processor is configured to perform processing including determining, based on condition of the engine and the oxygen concentration measured by the oxygen concentration detector, whether to prohibit the engine from being stopped.