Engine Return Rich Control Period Adjustment
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Solution Overview
Problem
When an engine is intermittently stopped during return rich control and then restarted, the total period of return rich control becomes long, leading to increased hydrocarbons in exhaust gas and deteriorated emissions.
Innovation Solution
The engine device executes return rich control for a shorter period after restart, using counters to manage the control duration and adjust the air-fuel ratio, thereby reducing the overall period of return rich control and hydrocarbon emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the return rich control is executed for a predetermined period after engine restart, then the engine can properly recover from fuel cut conditions, but the total period of return rich control becomes long and hydrocarbon emissions increase
Solution Approach 1:
The patent applies dynamics by making the return rich control period variable rather than fixed. The control period is dynamically adjusted based on whether the engine was intermittently stopped during fuel cut. When intermittent stop is detected, the return rich control period is shortened; when not detected, the full predetermined period is executed. This dynamic adjustment resolves the contradiction by adapting the control duration to actual operating conditions.
Solution Approach 2:
The patent changes the parameter of control period duration based on detected operating conditions. By detecting intermittent stop conditions and adjusting the return rich control period parameter accordingly (shortening it when intermittent stop is detected), the system optimizes the balance between reliable engine recovery and emission suppression.
2Reliability
If the return rich control period is extended to ensure proper engine recovery, then engine reliability improves, but the amount of hydrocarbons in exhaust gas increases
Solution Approach 1:
The system dynamically adjusts the return rich control period based on actual engine operation conditions. When intermittent stop is detected during fuel cut, the control period is shortened to prevent excessive hydrocarbon accumulation. When intermittent stop is not detected, the full period ensures proper recovery. This dynamic parameter adjustment resolves the contradiction between reliability and emission quantity.
Solution Approach 2:
The control period parameter is changed based on detected conditions. The ECU detects intermittent stop conditions and adjusts the return rich control period parameter accordingly, changing it from a fixed predetermined period to a variable period that optimizes both engine reliability and hydrocarbon emission control.
3Device complexity
If the return rich control is executed for a fixed predetermined period, then the control logic is simple, but the total control period becomes excessively long when engine is intermittently stopped and restarted
Solution Approach 1:
The patent transforms the static fixed period control into a dynamic adaptive control. By introducing detection of intermittent stop conditions and dynamically adjusting the control period based on detection results, the system prevents excessive total control time while maintaining manageable control logic through structured detection and conditional execution.
Solution Approach 2:
The system implements feedback by detecting whether the engine was intermittently stopped during fuel cut and using this information to adjust the return rich control period. This feedback mechanism allows the control period to be optimized based on actual operating conditions, preventing excessive total control time while maintaining clear control logic.
Data Source
AI summary
An engine device includes: an engine; and a control device that executes a return rich control that controls the engine so that an air-fuel ratio becomes rich over a predetermined period after the engine returns from the fuel cut. When the engine is intermittently stopped during the execution of the return rich control, the return rich control is executed for a period shorter than the predetermined period after the engine is restarted. Thus, when the engine is intermittently stopped during the execution of the return rich control and the engine is restarted thereafter, it is possible to suppress a total period of the return rich control from becoming long. As a result, it is possible to suppress an increase in the amount of hydrocarbons in the exhaust gas and suppress deterioration of emissions.