Torque Correction Table for Diesel Engine NOx Purification
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Solution Overview
Problem
Existing exhaust gas purifying systems using NOx storage-reduction catalysts face challenges in suppressing variations in engine torque, exhaust gas composition, and combustion noise during the transition from a lean to a rich state, particularly due to changes in intake air amount.
Innovation Solution
The system employs a NOx storage-reduction catalyst, a fuel injection apparatus, and a control apparatus that measures intake air using a MAF sensor to create a torque correction table, allowing for adjustments in fuel injection amount and timing to maintain engine torque stability during rich reduction states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the exhaust gas is switched from lean state to rich state for NOx reduction, then the NOx purification effect is improved, but the engine torque varies and combustion noise changes due to response delays between intake system and fuel system
Solution Approach 1:
The control apparatus performs preliminary correction of fuel injection amount and timing based on predicted intake air amount changes before the actual switching occurs. By calculating the expected variation in intake air amount and pre-adjusting the fuel injection parameters, the system compensates for the response delay between the intake system and fuel system, thereby maintaining engine torque stability during the transition to rich state for NOx reduction
Solution Approach 2:
The control apparatus continuously monitors the actual intake air amount using the air amount sensor and compares it with the predicted value. Based on the deviation between actual and predicted intake air amount, the control apparatus dynamically adjusts the fuel injection amount and timing corrections, creating a closed-loop feedback system that maintains torque stability while enabling effective NOx reduction through rich state switching
2Adaptability or versatility
If the intake air amount varies during rich state operation, then the system can adapt to different operating conditions, but the engine torque varies and exhaust gas composition deteriorates
Solution Approach 1:
The control apparatus dynamically adjusts the fuel injection amount and timing based on the actual intake air amount measured by the air amount sensor during rich state operation. By continuously updating the correction values according to varying operating conditions, the system maintains optimal exhaust gas composition and engine torque across different intake air amounts, transforming a static control approach into a dynamic adaptive system
Solution Approach 2:
The control apparatus changes the fuel injection parameters (amount and timing) in response to variations in intake air amount during rich state operation. By adjusting these critical parameters based on real-time sensor feedback, the system compensates for intake air variations and maintains stable exhaust gas composition and engine performance across different operating conditions
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 effectively suppresses engine torque variations, exhaust gas composition deterioration, and combustion noise changes by correcting fuel injection parameters based on intake air amount changes, ensuring consistent engine performance during rich reduction.
Implementation Method 1
an air amount sensor that measures an intake air amount
Implementation Method 2
a NOx storage-reduction catalyst that stores NOx when exhaust gas flowing through an exhaust passage of an engine is in a lean state
Implementation Method 3
reduces the stored NOx when the exhaust gas is in a rich state
Data Source
AI summary
A control apparatus (12): creates a torque correction table indicating a relationship between a change rate of an intake air amount, a change of the main injection amount and the main injection timing of a fuel injection apparatus (8) in the torque value of a diesel engine (1) in a lean state; measures an intake air amount in a rich state by using an MAF sensor (11); calculates a change rate of the measured intake air amount for the intake air amount in the lean state; obtains a correction value of the main injection amount and a correction value of the main injection timing of the fuel injection apparatus (8) based on the calculated change rate and the torque correction table; and performs an injection of the fuel in the rich state at the main injection amount and the main injection timing, corrected by the respective correction values.