Urea Injection Valve Anti-Clogging Control
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Solution Overview
Problem
The exhaust gas purification system faces issues with clogging of the reducing agent injection valve due to solidified urea aqueous solution when the engine is stopped, leading to decreased purification efficiency.
Innovation Solution
Incorporating a condition satisfaction determination section to assess the likelihood of urea aqueous solution solidification and an internal-combustion engine stop prevention section to maintain cooling water circulation, preventing the engine from stopping if solidification is detected, thus avoiding clogging and maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is stopped to save energy, then energy consumption is reduced, but the cooling water circulation stops causing urea aqueous solution to solidify and clog the injection valve
Solution Approach 1:
The control device predicts the temperature change of the reducing agent injection valve when the engine is stopped, and determines in advance whether the urea aqueous solution will solidify. Based on this prediction, the system decides whether to maintain cooling water circulation or to purge the urea solution before stopping, preventing solidification clogging while avoiding unnecessary energy consumption.
Solution Approach 2:
The system uses the engine's own cooling water circulation system to prevent solidification of the urea aqueous solution in the injection valve. By maintaining cooling water flow during engine operation and using it to cool the injection valve, the system leverages existing resources to solve the solidification problem without requiring separate heating or insulation systems.
2Reliability
If cooling water circulation is maintained after engine stop to prevent solidification, then injection valve reliability is improved, but energy consumption increases
Solution Approach 1:
The control device continuously monitors the engine operation state and temperature conditions, and adjusts the cooling water circulation and urea supply accordingly. When the engine is stopped, the system determines based on predicted temperature changes whether to maintain cooling, purge urea, or both, optimizing energy usage while preventing solidification.
Solution Approach 2:
The system changes the operational parameters of the cooling water circulation system and urea supply system based on engine state. During engine operation, cooling water circulates and urea is supplied; when stopped, the system adjusts these parameters dynamically - either maintaining cooling for a period, purging the urea solution, or both - to prevent solidification while minimizing energy consumption.
3Productivity
If urea aqueous solution concentration is increased to improve purification efficiency, then NOx purification efficiency is improved, but the solidification temperature increases causing clogging risk
Solution Approach 1:
The system manages the concentration parameter of the urea aqueous solution by controlling the urea supply amount and timing. By adjusting when and how much urea is supplied, the system maintains the necessary concentration for effective NOx purification while preventing the solution from becoming too concentrated and solidifying in the injection valve during engine stop 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
Prevents clogging of the reducing agent injection valve and maintains exhaust gas purification efficiency by ensuring the urea aqueous solution does not solidify, even after the engine is stopped.
Implementation Method 1
a heating section for heating the urea aqueous solution in the reducing agent injection valve
Implementation Method 2
the heat dissipation function of the reducing agent injection valve, such as circulation of cooling water, stops, causing the temperature of the reducing agent injection valve to increase
Implementation Method 3
water contained in the urea aqueous solution left in the reducing agent injection valve decreases due to evaporation, causing the concentration of the urea aqueous solution to increase
Implementation Method 4
the temperature of the urea aqueous solution decreases as the temperature of the exhaust pipe and the ambient temperature decrease, but, since the concentration has become higher than usual, the solidification temperature has also become higher, which may cause the urea aqueous solution to be solidified
Data Source
AI summary
An exhaust gas purification system capable of preventing clogging of a reducing agent injection valve due to solidified urea aqueous solution to prevent a decrease in the exhaust gas purification efficiency of an internal-combustion engine. The exhaust gas purification system includes a diesel particulate filter, a reducing agent injection valve and an SCR catalyst in this order from the exhaust upstream side. A condition satisfaction determination section determines whether or not urea aqueous solution is likely to be solidified when detecting that an ignition switch is turned off, and an internal-combustion engine stop prevention section prevents the internal-combustion engine from being stopped, based on a determination by the condition satisfaction determination section.