Air-Bypass Valve Control for Turbo Engine Stall Prevention
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Solution Overview
Problem
Existing engine control systems for supercharged engines with high-pressure fuel systems face delays in responding to abnormalities, leading to potential engine stalls due to the inertia of rotary components and longer diagnosis times in characteristic fuel pressure transitions, which can result in insufficient suppression of in-cylinder pressure.
Innovation Solution
An engine control device that includes an air-bypass valve control unit to increase the opening degree of the air-bypass valve in response to detected abnormalities in the high-pressure fuel system, combined with a waste gate valve control to reduce supercharging pressure, ensuring timely prevention of engine stalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If waste gate valve control is used to reduce supercharging pressure, then fuel injection can be maintained during abnormality, but response delay occurs due to inertia of rotary components
Solution Approach 1:
The patent divides the supercharging pressure control function into two separate systems: a waste gate valve system for gradual pressure reduction and an air-bypass valve system for immediate pressure reduction. This segmentation allows the system to select the appropriate response speed based on the severity and timing of abnormality detection, resolving the contradiction between reliable fuel injection maintenance and fast response time.
Solution Approach 2:
The air-bypass valve is positioned upstream of the compressor and can be opened in advance or immediately upon abnormality detection to prevent pressure buildup before it reaches critical levels. This preliminary action eliminates the response delay inherent in waste gate valve control, enabling the system to maintain fuel injection reliability without time loss.
2Measurement precision
If characteristic diagnosis of fuel pressure transition is performed, then accurate abnormality detection is achieved, but detection time is extended
Solution Approach 1:
The patent implements a dynamic diagnosis approach where the system continuously monitors fuel pressure transitions and adapts the diagnosis timing based on operating conditions. By using multiple judgment timings (first judgment before characteristic diagnosis, second judgment after), the system achieves accurate abnormality detection without excessive delay, balancing measurement precision with acceptable diagnosis time.
Solution Approach 2:
The system employs feedback mechanisms where the results of characteristic diagnosis feed back into the control strategy. When abnormality is detected through precise characteristic analysis, the air-bypass valve control is activated. This feedback loop ensures that accurate detection is achieved at the appropriate moment, minimizing unnecessary delay while maintaining high measurement precision.
3Speed
If air-bypass valve opening degree is increased, then supercharging pressure is reduced immediately, but intake air amount is affected
Solution Approach 1:
The patent changes the parameter of air-bypass valve opening degree dynamically based on the detected abnormality and current operating conditions. By adjusting the opening degree rather than simply opening or closing the valve, the system achieves immediate supercharging pressure reduction while minimizing the impact on intake air amount, thus resolving the contradiction between fast pressure reduction and maintaining adequate air supply.
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
The solution enables immediate reduction of supercharging pressure by opening the air-bypass valve, effectively preventing engine stalls even when abnormalities are detected during longer characteristic diagnosis times, compared to relying solely on waste gate valve control.
Implementation Method 1
an air-bypass valve provided in an air-bypass passage that allows fresh air to bypass the compressor
Implementation Method 2
a waste gate valve provided in a waste gate passage that allows the exhaust gas to bypass the turbine
Implementation Method 3
a turbo-supercharger that has a turbine to be driven by exhaust gas and a compressor to be driven by the turbine
Implementation Method 4
a high-pressure fuel pump configured to boost a pressure of fuel supplied from a feed pump
Data Source
AI summary
An engine control device controls an engine including a turbo-supercharger, a waste gate valve, an air-bypass valve, and a high-pressure fuel system. The engine control device includes: an air-bypass valve control unit and an abnormality detection unit. The air-bypass valve control unit controls the air-bypass valve. The abnormality detection unit detects an abnormality in the high-pressure fuel system. The air-bypass valve control unit increases an opening degree of the air-bypass valve in accordance with detection of the abnormality by the abnormality detection unit.