Urea Water Supply System Thawing Control
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Solution Overview
Problem
The existing urea water supply system for selective reduction catalysts in engines delays the injection of urea water due to its reliance on engine rotation speed and thawing time, which hampers the purification of nitrogen oxides in exhaust gas.
Innovation Solution
A urea water supply system with a temperature raising device, state acquisition device, and control device that determines the thawing state of urea water and permits injection based on temperature and time criteria, allowing for early and reliable thawing by shortening the permission determination time upon system restart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system waits for engine rotation speed to reach threshold and thawing time to elapse before injection, then reliable thawing is ensured, but injection is delayed and nitrogen oxide purification is postponed
Solution Approach 1:
The control device performs preliminary thawing of urea water using the temperature raising device before injection is needed. By pre-raising the temperature of urea water in the tank above its freezing point, the system ensures that when injection is required, the urea water is already in a thawed state, eliminating the need to wait for thawing time to elapse after engine start.
Solution Approach 2:
The system uses the engine's own cooling water as the heating medium for the temperature raising device. The cooling water, which is already circulating through the engine at operating temperature, is directed through a heat exchange mechanism to warm the urea water tank, allowing the system to utilize its own thermal resources for thawing without external heating equipment.
2Productivity
If the determination time for injection permission is shortened upon system restart, then injection can start earlier, but the risk of injecting frozen urea water increases
Solution Approach 1:
The control device continuously monitors the temperature of urea water in the tank and uses this feedback information to determine whether injection permission should be granted. By reading the temperature data from the temperature sensor and comparing it against predetermined thresholds, the system can reliably determine thawing status and make informed injection decisions, even with shortened determination time.
Solution Approach 2:
The system performs preliminary temperature raising of urea water before injection is requested, so that when the system restarts after a stop period, the urea water is already in a thawed state. This preliminary action eliminates the need for lengthy thawing verification processes during restart, allowing faster injection permission determination while maintaining reliability.
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 enables the urea water to be injected at an earlier stage while ensuring it is reliably thawed, thereby reducing the time required for nitrogen oxide purification.
Implementation Method 1
a temperature raising device which raises a temperature of urea water
Implementation Method 2
when the urea water stored in a tank is supplied to a urea water injection valve by a pump
Data Source
AI summary
A urea water supply system which performs permission determination by a control device based on a first parameter includes a cooling water temperature sensor, and a control device is configured to be able to store a result of the permission determination, and when a system control is restarted after the system control is stopped and a stop period is elapsed, it performs a shortening setting to shorten a time required for the permission determination based on the determination result stored at a time when the system is stopped and a cooling water temperature immediately after restarting.