EGR Valve Control Strategy for Pedal Tip-Out Stability
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Solution Overview
Problem
Existing EGR systems face challenges in managing exhaust gas recirculation during accelerator pedal tip-out transitions, balancing the need for reduced EGR flow to prevent engine instability while maintaining fuel economy and emission reduction benefits.
Innovation Solution
The method involves controlling the EGR valve based on the accelerator pedal position using a calibrated table for immediate closure and performing active torque management through throttle adjustment and fuel reduction to match driver-requested torque, distinguishing between slow and fast paths to stabilize engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the EGR rate is limited to a containable level during pedal tip-out, then engine stability is maintained, but fuel economy and emission reduction benefits are compromised
Solution Approach 1:
The EGR valve control system dynamically adjusts the EGR rate based on real-time accelerator pedal position and predefined closing limits. During pedal tip-out transitions, the system actively modulates the EGR valve to maintain stability while preserving beneficial EGR flow, rather than using a static limited approach.
Solution Approach 2:
The system changes the EGR valve closing limits parameter based on accelerator pedal position. By indexing a table of closing limits according to pedal position, the system adapts the EGR rate parameters to match driving conditions, enabling higher EGR rates during normal operation while maintaining controllability during tip-out transitions.
2Reliability
If the throttle is delayed in closing during pedal tip-out to allow recirculated exhaust gas to exit, then safety concerns are avoided, but engine combustion instability occurs
Solution Approach 1:
The control system continuously monitors accelerator pedal position and engine operating conditions, using this feedback to determine the appropriate EGR valve closing action. This closed-loop control enables the system to respond appropriately to pedal tip-out while maintaining combustion stability through active EGR management.
Solution Approach 2:
The system uses predefined EGR valve closing limits indexed by accelerator pedal position to prepare appropriate closing actions in advance. This preliminary structuring of control parameters allows the system to execute the correct EGR valve closing strategy without delay when pedal tip-out is detected.
3Stability of the object's composition
If the EGR valve closes immediately during pedal tip-out to prevent combustion instability, then combustion stability is maintained, but the response time and driver torque perception are delayed
Solution Approach 1:
The EGR valve control system dynamically adjusts the closing speed and timing based on the rate of change of accelerator pedal position. During rapid tip-out events, the system modulates the EGR valve closure to match the urgency of the driver's action, providing appropriate response time while maintaining combustion stability.
4Loss of energy
If high EGR rates are used during partial load operation, then fuel economy improves and emissions are reduced, but engine tolerance for EGR flow decreases at idle and during transitions
Solution Approach 1:
The system changes the EGR valve closing limits parameter based on accelerator pedal position and engine operating conditions. By indexing a table of closing limits according to pedal position, the system adapts the EGR rate parameters to match driving conditions, enabling higher EGR rates during partial load while maintaining appropriate limits during idle and transition periods.
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 approach enables faster EGR valve response and stable engine torque during pedal tip-out transitions, improving fuel efficiency and reducing emissions without compromising vehicle safety or drivability.
Implementation Method 1
In an EGR system, a portion of an engine's exhaust gas is recirculated back to the engine cylinders
Implementation Method 2
The introduction of vehicle exhaust into the combustion chamber has a number of consequences... This results in a chemical slowing and cooling of the combustion process by several hundred degrees Fahrenheit... The lower temperature leads to a reduced formation rate for nitrous oxide emissions
Implementation Method 3
controlling an exhaust gas recirculation valve based on a current position of a vehicle accelerator pedal and predetermined exhaust gas recirculation valve closing limits
Implementation Method 4
performing active torque management based on driver requested torque in a slow path and driver requested torque in a fast path
Data Source
AI summary
A method for controlling a vehicle's exhaust gas recirculation system. The method controls the exhaust gas recirculation system in a manner that is suitable for a pedal tip-out transition while also being optimized for normal operating situations.