EGR Valve Full-Close Position Learning via Torque Peak Detection

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Solution Overview

Problem

Existing EGR systems for internal combustion engines face challenges in accurately determining the full-close position of the EGR valve, which is crucial for preventing EGR gas leakage, especially in gasoline engines where combustion stability sensitivity is high.

Innovation Solution

An EGR controller that utilizes a driving-torque-information detecting portion to learn the full-close position of the EGR valve by maximizing the driving torque, allowing for precise determination of the valve's opening degree when the torque becomes maximal, thereby ensuring accurate closure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods (oxygen sensor or intake pressure sensor) are used to detect EGR valve position, then the system can operate with simpler sensor configurations, but the full-close position learning accuracy is insufficient to prevent EGR gas leakage

Engineering Contradiction:

Improvefull-close position learning accuracyVSAvoidsensor configuration complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional sensor-based detection methods (oxygen sensor, intake pressure sensor) with a torque-based detection method. The EGR controller monitors the driving torque of the EGR valve motor and identifies the full-close position by detecting the torque peak, eliminating the need for additional sensors and achieving higher positioning accuracy through mechanical/electrical parameter analysis.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system uses the EGR valve motor's own torque characteristics to determine its position. By monitoring the torque output of the motor during valve operation, the system self-determines the full-close position without requiring external sensors or additional measurement devices, making the system self-diagnostic and more accurate.

Inventive Principle:

Principle #25Self-service

2Reliability

If the EGR valve is controlled to fully close the EGR passage, then EGR gas leakage is prevented, but the combustion stability in gasoline engines becomes sensitive to positioning accuracy

Engineering Contradiction:

ImproveEGR gas leakage preventionVSAvoidcombustion stability sensitivity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces conventional position control methods with torque-based position identification. By using the torque peak detection method, the system achieves more reliable and accurate full-close positioning, which is critical for preventing EGR gas leakage and maintaining combustion stability in gasoline engines.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system continuously monitors the torque output of the EGR valve motor and uses this feedback to identify the full-close position. This closed-loop approach ensures that the valve reaches the correct position consistently, improving both leakage prevention and combustion stability.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8960169B2EGR controller for internal combustion engine

Publication Date: 2015.02.24 DENSO CORP

AI summary

When a constant driving voltage is applied to a motor driving an EGR valve so that the EGR opening degree is varied, an angular speed of the EGR valve becomes minimal at a position where the driving torque of the EGR valve becomes maximal. In view of this, while an opening degree of the EGR valve is varied with a constant driving voltage applied to the motor, the EGR opening degree where the angular speed becomes minimal is learned as a full-close position.