Wastegate Valve Position Learning for Turbocharged Engines
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Solution Overview
Problem
Existing control methods for internal combustion engines with turbochargers fail to accurately learn the fully closed position of the wastegate valve, leading to deviations in supercharging pressure due to factors other than the wastegate valve's fully closed position, resulting in deteriorated controllability and increased actuator driving force, which can cause joint member bending and erroneous position learning.
Innovation Solution
A control apparatus and method that calculates a target supercharging pressure, required opening, and opening correction amount, determines the actual opening of the wastegate valve based on its fully closed position, and updates the fully closed position only when the actual operating position is not decreasing at a preset rate, ensuring accurate learning of the wastegate valve's fully closed position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the fully closed position of the wastegate valve is learned based on the position sensor output when the target opening is the fully closed position, then the learning process is simple, but the learned position may be erroneous due to actuator driving force causing joint member bending
Solution Approach 1:
The control apparatus performs preliminary action by determining whether the wastegate valve has reached the fully closed state before learning the position. The learning process is executed only after confirming the valve is fully closed, preventing erroneous learning caused by joint member bending during the closing process. This preliminary verification step ensures accurate position learning without increasing overall system complexity.
2Speed
If feedback control is performed by setting a target having a smaller opening than the stopper position, then the wastegate valve closes forcefully, but the actuator driving force increases causing joint member bending
Solution Approach 1:
The control apparatus uses feedback control by monitoring the actual opening of the wastegate valve via the position sensor and comparing it with the target opening. The feedback loop adjusts the actuator driving force to achieve the target opening without excessive force, preventing joint member bending while maintaining adequate closing speed. The feedback mechanism ensures the valve closes smoothly without requiring oversized driving force.
3Reliability
If the fully closed position is learned when the internal combustion engine is warm, then temperature variation effects are minimized, but the learning can only be performed under specific operating conditions
Solution Approach 1:
The control apparatus applies local quality by determining the fully closed position under specific local conditions (when the engine is warm) where temperature effects are minimized. This localized learning approach ensures high reliability for the learned position. The system compensates for the limited learning conditions by using this reliable baseline position for control calculations across all operating conditions, including cold starts.
Data Source
AI summary
A required opening correction amount is calculated based on a target supercharging pressure and an actual supercharging pressure, a target opening is calculated based on a required opening and the required opening correction amount, an actual operating position of a wastegate valve is determined to correspond to a fully closed position when the wastegate valve is in a fully closed condition, an actual opening of the wastegate valve is calculated based on the fully closed position and the actual operating position, an operation amount of an actuator for aligning the target opening with the actual opening is calculated based on the target opening and the actual opening, and when the target opening corresponds to the fully closed condition and the actual operating position is not decreased at or above a prescribed rate, the fully closed position is updated to the actual operating position.