Air-Bypass Valve Control for Turbocharged Engine Surge Prevention
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Solution Overview
Problem
Existing air-bypass valve control systems for turbocharged engines fail to prevent compressor surge without deteriorating drivability, particularly due to inappropriate control leading to unnecessary valve opening and delayed response during re-acceleration.
Innovation Solution
An air-bypass valve control device that temporarily opens the air-bypass valve when the intake air amount is equal to or larger than a predetermined value and extends the valve open period based on increased intake air amount and decreased engine rotational speed, while maintaining the valve closed during non-travel states and high throttle opening degrees.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air-bypass valve is opened to prevent compressor surge, then compressor surge is inhibited, but the response time during re-acceleration is delayed
Solution Approach 1:
The controller predicts the occurrence of compressor surge by monitoring current operating parameters (intake air amount, throttle valve opening degree, engine rotational speed) before surge actually occurs. By taking preliminary action to close the air-bypass valve in advance based on prediction, the system prevents surge without maintaining unnecessary valve opening that would delay re-acceleration response.
Solution Approach 2:
The control system dynamically adjusts the air-bypass valve opening/closing timing and duration based on real-time operating conditions. The valve is opened only for the minimum necessary duration to prevent surge, and closed promptly when protection is no longer needed, optimizing both surge prevention and re-acceleration response characteristics.
2Reliability
If the air-bypass valve is opened frequently to ensure surge prevention, then compressor reliability is improved, but drivability deteriorates due to actuation noise and timing delays
Solution Approach 1:
By predicting surge occurrence before it happens, the system can prepare the air-bypass valve in advance, reducing the need for frequent emergency openings. This preliminary prediction-based control minimizes unnecessary valve actuations that generate noise and improve drivability while maintaining reliable surge protection.
Solution Approach 2:
The controller continuously monitors operating parameters and uses feedback from the engine management system (including accelerator pedal position and engine load) to intelligently determine when valve actuation is truly necessary. This feedback mechanism reduces unnecessary actuations that create noise while ensuring protection when actually needed.
Data Source
AI summary
An air-bypass valve control device is disposed in an engine. The engine includes an intake passage, a compressor, a throttle valve, an air-bypass passage and the air-bypass valve. The air-bypass valve control device includes an intake air amount detector, a controller. The intake air amount detector detects an intake air amount of the engine. The controller configured to temporarily bring the air-bypass valve into an opened state in the case where the intake air amount of the engine immediately before a decrease in an opening degree of the throttle valve is equal to or larger than a predetermined value when the opening degree of the throttle valve decreases at a predetermined speed or higher.