Intake Air Flow Rate Detection with Bypass Valve Recirculation
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Solution Overview
Problem
Existing supercharging internal combustion engines face precision issues in detecting intake air flow rates during vehicle deceleration due to recirculation of air, leading to inappropriate control based on engine operating conditions.
Innovation Solution
The system employs a bypass valve and controller to calculate intake air flow rates using engine rotation speed and pressure sensors, adjusting fuel injection based on bypass valve opening to maintain precision, even when air recirculates back to the air flow meter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If air recirculation is used to control supercharging pressure, then supercharging pressure can be maintained within appropriate ranges, but intake air flow rate detection precision deteriorates when circulated air flows back to the air flow meter
Solution Approach 1:
The patent introduces a bypass valve as an intermediary component that provides an alternative path for circulated air to return to the intake passage upstream of the air flow meter. This mediator prevents the direct backflow of circulated air to the air flow meter, thereby maintaining detection precision while still enabling air recirculation for supercharging pressure control
Solution Approach 2:
The patent segments the air circulation path by creating a bypass passage that is separate from the main intake passage. This segmentation allows circulated air to be diverted through the bypass valve and returned to the intake passage at a location upstream of the air flow meter, preventing contamination of the detection zone while maintaining the recirculation function
2Measurement precision
If air flow meter output is limited to predetermined range during vehicle deceleration, then detection precision deterioration is suppressed, but control is not always performed appropriately in accordance with engine operating condition
Solution Approach 1:
The patent implements a dynamic control strategy where the bypass valve opening is adjusted based on real-time detection of circulation air flow rate. The controller continuously monitors the actual operating conditions and adapts the bypass valve position accordingly, enabling appropriate control across varying engine operating conditions rather than applying fixed limitation ranges
3Stress or pressure
If bypass valve opens to circulate air, then supercharging pressure increase is suppressed, but intake air flow rate detection becomes inaccurate due to backflow to air flow meter
Solution Approach 1:
The bypass valve acts as an intermediary that redirects circulated air through a separate bypass passage to return to the intake passage upstream of the air flow meter. This intermediary mechanism enables supercharging pressure control through air circulation while preventing the circulated air from contaminating the air flow meter detection zone, thereby maintaining detection accuracy
Data Source
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AI summary
An intake air flow rate detection device for an internal combustion engine (100), including a sensor (61, 63) that detects an operating condition of the internal combustion engine (100), an air flow meter (21) that disposed in the intake passage (20) upstream of the supercharging device (41), and a programmable controller (60) programmed to calculate a measured intake air flow rate from a detection value of the air flow meter (21), calculate a calculated intake air flow rate from the operating condition of the internal combustion engine (100), and employ either the measured intake air flow rate or the calculated intake air flow rate as an intake air flow rate of the intake passage (20) on the basis of an air flow rate of air that is circulated to the intake passage (20) between the air flow meter (21) and the supercharging device (41) through the bypass passage (51).