Exhaust Gas Purification Device Multistage Injection Low Temperature
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Solution Overview
Problem
Existing exhaust gas purification devices face challenges in low temperature conditions, leading to unstable combustion, filter clogging, and reduced NOx reduction efficiency, especially during idling and low load operations, where fuel injection at low temperatures results in fuel adherence and smoke generation.
Innovation Solution
An exhaust gas purification device with an upstream fuel injection system, including a first catalyst for thermal decomposition and a second catalyst for maintaining catalyst temperatures above 200°C, along with an exhaust gas temperature estimator and regeneration control unit, performs a multistage injection to ensure efficient thermal decomposition and regeneration, even at low temperatures, using an electric heater if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multistage injection is performed to raise exhaust gas temperature during low temperature operations, then fuel thermal decomposition is improved and smoke generation is reduced, but combustion becomes concentrated in expansion stroke causing unstable combustion and deteriorated drivability
Solution Approach 1:
The injection process is divided into multiple stages: a first injection before compression stroke to raise exhaust gas temperature, and a second injection during compression stroke to maintain stable combustion. This segmentation allows each injection to serve its specific function without compromising overall combustion stability.
Solution Approach 2:
The first injection is performed preliminarily before the compression stroke to pre-heat the exhaust gas and raise the temperature of the decomposition catalyst. This preliminary action ensures that when the second injection occurs, the conditions are already favorable for stable combustion and effective fuel decomposition.
2Ease of operation
If normal injection is performed in low load region, then drivability is maintained, but exhaust gas temperature decreases causing fuel adherence to exhaust pipe and smoke generation
Solution Approach 1:
The system periodically monitors exhaust gas temperature and switches between normal injection and multistage injection modes based on temperature conditions. This periodic action ensures that fuel injection timing is adjusted appropriately to prevent adherence while maintaining drivability.
Solution Approach 2:
The injection timing and pattern parameters are changed based on exhaust gas temperature conditions. When temperature is low, the system transitions to multistage injection with specific timing adjustments to raise temperature and prevent fuel adherence, while restoring normal injection parameters when temperature is sufficient.
3Productivity
If in-exhaust pipe injection is performed at low exhaust gas temperature, then regeneration can be initiated, but fuel arrives at catalysts before thermal decomposition causing filter clogging and reduced NOx reduction efficiency
Solution Approach 1:
The first injection stage performs preliminary heating of the exhaust gas and catalyst before the main fuel injection for regeneration. This ensures the catalyst reaches the necessary temperature for effective thermal decomposition before large amounts of fuel are introduced, preventing clogging and ensuring proper regeneration.
Solution Approach 2:
The decomposition catalyst acts as an intermediary that must reach a specific temperature before fuel can be effectively decomposed. The first injection stage serves as a mediator to bring the catalyst to the required temperature, enabling the second stage to proceed without causing clogging or reducing efficiency.
4Temperature
If multistage injection with retarded timing is used, then exhaust gas temperature increases, but air-fuel ratio decreases and in-cylinder pressure reduces causing acceleration failure
Solution Approach 1:
The injection process is segmented into two distinct stages with different timing characteristics. The first stage uses retarded timing to raise exhaust gas temperature, while the second stage uses appropriate timing to maintain in-cylinder pressure and acceleration performance, thus resolving the contradiction between temperature increase and pressure maintenance.
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 configuration enhances low-temperature performance, increases NOx reduction efficiency, reduces smoke generation, and stabilizes combustion, thereby improving drivability and reducing manufacturing costs by maintaining catalyst temperatures and controlling fuel injection patterns effectively.
Implementation Method 1
a first catalyst provided in the exhaust passage on an upstream side of the exhaust passage fuel injecting means
Implementation Method 2
a second catalyst provided in the exhaust passage between the exhaust passage fuel injecting means and the exhaust gas post-processing device in order to perform thermal decomposition on fuel injected by the exhaust passage fuel injecting means
Implementation Method 3
using an electric heater if necessary
Implementation Method 4
raises the temperatures of the respective catalysts through combustion of HC and CO
Data Source
AI summary
The exhaust gas purification device includes an exhaust gas post-processing device 30 provided in an exhaust passage 11 of an engine 10, an exhaust injection valve 22, a first catalyst 35, a second catalyst 36 for thermally decomposing fuel injected by the exhaust injection valve 22, an exhaust temperature estimation unit 41 for estimating an exhaust temperature, an engine injection control unit 42 for controlling fuel injection in the engine 10, and regeneration control units 43, 44 for controlling regeneration of the exhaust gas post-processing device 30. When an output value output by the exhaust gas temperature estimation unit 41 is equal to or lower than a threshold during regeneration by the regeneration control units 43, 44, the engine injection control unit 42 controls fuel injection in the engine by performing a multistage injection, which includes a post injection for supplying fuel to the first catalyst 35.