Exhaust Gas Purification System Air Flow Control Warm-Up
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Solution Overview
Problem
Existing exhaust gas purification systems for internal combustion engines face challenges in raising the temperature of exhaust gas purifiers, such as SCR units, during engine warm-up, which can lead to unstable combustion and increased HC emissions, especially when air flow control is initiated too early.
Innovation Solution
An exhaust gas purification system that includes an air flow control unit and an activation timing control unit, which reduces the air flow rate to the engine while controlling the timing of air flow control activation to maintain stable combustion, using methods like calculating a prescribed time based on engine rotation speed and fuel injection amount, or activating the air flow control after the engine has reached specific temperature thresholds, ensuring the combustion state remains stable during warm-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air flow rate is reduced to raise exhaust gas purifier temperature, then purifier temperature increases, but combustion stability deteriorates
Solution Approach 1:
The system performs preliminary actions (fuel injection timing control, EGR rate control) before reducing air flow rate to prepare the combustion system for the upcoming change, ensuring that combustion stability is maintained even when air flow is reduced for purifier heating
Solution Approach 2:
The system changes multiple parameters simultaneously (air flow rate, fuel injection timing, EGR rate) in a coordinated manner, where the adjustment of fuel injection timing and EGR rate compensates for the destabilizing effect of reduced air flow, thereby maintaining combustion stability while raising purifier temperature
2Loss of time
If air flow control is activated early to raise purifier temperature, then purifier activation is accelerated, but HC emissions increase due to unstable combustion
Solution Approach 1:
The system determines the optimal activation timing by assessing engine conditions in advance (rotation speed, fuel injection amount, temperature) and prepares the combustion parameters before activating air flow control, ensuring that combustion remains stable and HC emissions are suppressed even during early warm-up phase
Solution Approach 2:
The system uses feedback from engine sensors (rotation speed, temperature, pressure) to dynamically adjust the activation timing and control parameters, ensuring that air flow control is activated only when combustion conditions are suitable, thereby preventing HC emission increases while accelerating purifier activation
3Stability of the object's composition
If fuel injection timing is advanced to raise cylinder temperature, then combustion stability improves, but purifier temperature increase is delayed
Solution Approach 1:
The system merges multiple control functions (fuel injection timing control, EGR rate control, air flow control) into a coordinated control strategy that achieves both combustion stability and purifier temperature increase simultaneously, rather than treating them as separate conflicting objectives
Solution Approach 2:
The system dynamically adjusts multiple parameters (fuel injection timing, EGR rate, air flow rate) in a coordinated sequence, where initial fuel timing advancement stabilizes combustion, followed by EGR and air flow adjustments that maintain stability while directing sufficient heat to the purifier for temperature increase
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
The system effectively raises the temperature of exhaust gas purifiers while preventing unstable combustion and reducing HC emissions, ensuring stable engine operation and efficient exhaust gas purification during the warm-up phase.
Implementation Method 1
reducing a flow rate of air to be supplied to the engine so as to raise a temperature of exhaust gas exhausted from the engine
Data Source
Figure 1
Figure 2~3B
Figure 4A~4C
AI summary
It is intended to provide an exhaust gas purification system for an internal combustion engine, which is capable of suppressing HC emission increase and raising the temperature of an exhaust gas purifier at an early stage while maintaining stable combustion during the warm-up operation such as immediately after the engine starting. The system is provided with: an air flow control unit 50 for reducing a flow rate of air supplied to the engine 1 to raise a temperature of the exhaust gas exhausted from the engine 1; and an activation timing control unit 52 for controlling a timing of activating the air flow control unit 50, and the activation timing control unit is configured to control the timing of activating the air flow control unit 50 so that a combustion state in the engine 1 does not become unstable when the air flow control unit 50 is activated and the air to be supplied to the engine 1 is reduced.