Intake Control System for Maintaining EGR Valve Differential Pressure
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Solution Overview
Problem
Conventional intake control systems for internal combustion engines, when used in gasoline engines burning a stoichiometric air-fuel mixture, reduce fresh air intake and engine torque, leading to degraded drivability due to the method of ensuring differential pressure across the EGR valve.
Innovation Solution
An intake control system that adjusts the throttle valve and EGR valve to maintain required differential pressure across the EGR valve, ensuring accurate EGR control while maintaining fresh air intake, using operating condition detection and ECU-based calculations to set target air and EGR amounts, and feedback corrections to stabilize recirculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the intake throttle valve is throttled to increase the differential pressure across the EGR valve, then the differential pressure across the EGR valve is ensured and EGR control accuracy is improved, but the fresh air amount is reduced and engine torque is reduced, degrading drivability
Solution Approach 1:
The system dynamically adjusts the EGR valve opening degree based on the detected differential pressure across the valve. When the differential pressure is insufficient, the EGR valve opening is reduced to increase the pressure difference, thereby improving EGR control accuracy without maintaining a fixed throttle position that would continuously reduce torque
Solution Approach 2:
The control system changes the operating parameters by adjusting the EGR valve opening degree in response to differential pressure conditions. This parameter adjustment allows the system to optimize EGR control accuracy by modifying the valve opening to ensure adequate differential pressure, rather than relying on throttle valve adjustment that would reduce fresh air intake and torque
2Reliability
If the intake throttle valve is throttled to ensure differential pressure across the EGR valve, then the differential pressure is maintained for stable EGR recirculation, but the fresh air intake is reduced, making it impossible to meet driver torque demand
Solution Approach 1:
The system uses dynamic control of the EGR valve opening degree based on real-time differential pressure detection. This dynamic adjustment ensures that the EGR valve operates under stable recirculation conditions by maintaining adequate differential pressure across the valve, while avoiding the need for continuous throttle valve restriction that would degrade drivability
Solution Approach 2:
The control system implements feedback control by detecting the differential pressure across the EGR valve and adjusting the EGR valve opening degree accordingly. This feedback mechanism ensures stable EGR recirculation by maintaining the necessary pressure differential, while preserving fresh air intake and torque output through proper EGR valve modulation rather than throttle restriction
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
This system ensures high accuracy in EGR control and maintains engine drivability by stabilizing differential pressure across the EGR valve, preventing torque reduction and ensuring the required differential pressure is met, even in stoichiometric air-fuel ratios.
Implementation Method 1
a differential pressure across the EGR valve is calculated, and if the calculated across-valve differential pressure is not more than a predetermined value, the intake throttle valve is throttled to thereby increase the across-valve differential pressure
Implementation Method 2
an intake throttle valve that is disposed in an intake passage, for adjusting an amount of fresh air drawn into a combustion chamber
Implementation Method 3
an EGR passage that is connected to an exhaust passage and a portion of the intake passage downstream of the intake throttle valve, for recirculating part of exhaust gases discharged into the exhaust passage
Data Source
AI summary
An intake control system for an internal combustion engine is capable of ensuring a differential pressure across an EGR valve, and controlling an EGR amount with high accuracy. A target fresh air amount is set based on a demanded torque calculated according to operating conditions of the engine. A differential pressure across an EGR valve is set as a target differential pressure. When it is determined that the across-valve differential pressure is not in a state in which the target differential pressure can be ensured, an opening degree of the EGR valve is controlled to limit an EGR amount. An opening degree of a throttle valve is controlled based on the target fresh air amount, so as to ensure the target differential pressure.