Engine Controller Bypass Valve Logic for Intake Backflow
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Solution Overview
Problem
Existing internal combustion engine controllers with forced induction devices face challenges in preventing alternating backflow, which occurs when intake air has no place to flow due to throttle valve closure, leading to inaccurate air flow meter readings and potential surging issues, especially in regions with small pressure ratios and air flow amounts.
Innovation Solution
A controller that determines the opening condition for air bypass valves based on the decrease speed of the target throttle passage amount and pressure ratio, ensuring the valves open when the throttle valve is likely to be closed, thereby preventing alternating backflow by releasing intake air through bypasses, even at small pressure ratios or air flow amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the throttle valve is closed to control air flow, then the amount of intake air is reduced, but the intake air flows backward into the compressors causing alternating backflow
Solution Approach 1:
The controller opens the air bypass valve in advance when predicting that the throttle valve will be closed or the amount of intake air will be reduced. This preliminary action prevents alternating backflow by providing an escape path for compressed air before the throttle closure causes pressure buildup and reverse flow.
Solution Approach 2:
The air bypass valve acts as an intermediary component that provides an alternative path for intake air to escape when the throttle valve closes. This mediator prevents the direct harmful interaction between the closed throttle valve and the compressors, eliminating alternating backflow while maintaining engine control.
2Reliability
If the air bypass valves are opened to prevent alternating backflow, then the intake air is released, but the valves may open unnecessarily reducing engine efficiency
Solution Approach 1:
The controller continuously monitors the amount of intake air and pressure ratio, using this feedback to intelligently determine when to open or close the air bypass valve. This feedback mechanism ensures the valve opens only when necessary to prevent alternating backflow, maintaining engine efficiency by avoiding unnecessary openings.
Solution Approach 2:
The air bypass valve operates dynamically based on real-time engine conditions rather than remaining statically open or closed. The controller adjusts the valve state according to changing intake air amounts and pressure ratios, optimizing both alternating backflow prevention and engine efficiency across different operating conditions.
3Reliability
If the controller opens air bypass valves in regions with small pressure ratio, then alternating backflow is prevented, but the valves open more frequently than necessary
Solution Approach 1:
The controller uses feedback from pressure ratio and intake air amount sensors to make informed decisions about bypass valve operation. By considering both parameters together, the controller avoids unnecessary valve openings in small pressure ratio regions where alternating backflow is unlikely, reducing wasted operations while maintaining reliability.
Data Source
AI summary
A controller for an internal combustion engine includes an intake air amount obtaining unit, an open-closed determination unit, and an air bypass valve control unit. The intake air amount obtaining unit is configured to obtain, using a target torque of the internal combustion engine, a target throttle passage amount as a target value of an amount of intake air drawn through a throttle valve. The open-closed determination unit is configured to determine whether a valve opening condition for first and second air bypass valves is satisfied. The air bypass valve control unit is configured to open the first and second air bypass valves when the valve opening condition is satisfied. The open-closed determination unit is configured to determine that the valve opening condition is satisfied when a decrease speed of the target throttle passage amount is greater than a specified determination speed.