Urea SCR Pipe Clogging Detection via Temperature and Pressure Analysis
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Solution Overview
Problem
Current urea SCR systems cannot accurately distinguish between clogging caused by foreign matter and freezing in the urea water piping, leading to incorrect determination of system abnormalities.
Innovation Solution
A urea water pipe clogging detection device that uses a combination of sensors (urea water temperature, pressure, and exhaust gas temperature sensors) and a clogging determination unit to differentiate between clogging due to foreign matter and freezing by performing startup and emptying control procedures, and utilizing a thawing unit to address freezing issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If abnormality determination is based on purification rate detection, then it is possible to detect whether clogging has occurred, but it cannot distinguish between catalyst abnormality and urea water spraying system abnormality
Solution Approach 1:
The patent segments the clogging detection function into multiple independent detection paths: one for detecting clogging occurrence via purification rate, and another for identifying the cause via temperature and pressure sensors. This allows the system to both detect clogging and distinguish its cause without conflating the two functions.
Solution Approach 2:
The patent introduces temperature sensors and pressure sensors as intermediary detection means that provide additional information about the system state. These intermediaries enable differentiation between freezing conditions (low temperature) and foreign matter clogging (normal temperature), resolving the information loss problem.
2Reliability
If the system waits for thawing before determining clogging, then freezing-related clogging is avoided, but the system cannot determine whether clogging is caused by foreign matter or freezing
Solution Approach 1:
The patent performs preliminary temperature and pressure measurements before clogging determination to identify the cause. By checking temperature and pressure conditions in advance, the system can distinguish between freezing and foreign matter clogging, allowing appropriate actions to be taken without waiting for thawing to occur.
Solution Approach 2:
The patent implements feedback loops where temperature and pressure sensor data continuously inform the clogging determination logic. This feedback mechanism allows the system to update its understanding of the clogging cause based on real-time sensor readings, improving reliability while maintaining cause identification capability.
3Measurement precision
If multiple sensors and control procedures are added to distinguish clogging causes, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent makes existing sensors (temperature and pressure sensors already present in the SCR system) serve the additional function of clogging cause identification. By utilizing sensors that already exist for other purposes, the system achieves improved detection accuracy without adding dedicated hardware specifically for clogging detection.
Solution Approach 2:
The system uses its own existing sensor network and control infrastructure to perform clogging diagnosis. The temperature and pressure sensors, along with the existing control unit, work together to automatically differentiate clogging causes without requiring external diagnostic equipment or complex additional subsystems.
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
Accurately detects clogging caused by foreign matter while differentiating it from freezing, ensuring proper system operation and preventing misinterpretation of freezing as a foreign matter clog.
Implementation Method 1
a urea water sensor configured to detect urea water temperature in the urea water tank
Implementation Method 2
a pressure sensor configured to detect pressure of the pressurized urea water feed line
Implementation Method 3
an exhaust gas temperature sensor disposed on an exhaust pipe upstream of the SCR device
Implementation Method 4
a supply pump configured to suck urea water from a urea water tank... perform startup control for driving the supply pump and increasing the pressure in the pipe segment
Implementation Method 5
drive a thawing unit for causing an engine cooling water to flow into the urea water tank and the dosing valve so as to thaw frozen urea
Data Source
AI summary
A clogging detection device includes a urea water sensor which detects temperature in a urea water tank, a pressure sensor which detects pressure in a urea water feed line, an exhaust gas temperature sensor disposed in an exhaust pipe upstream of a selective catalytic reduction device, and a determination unit. When a key switch is turned on, the determination unit performs a startup control to drive a supply pump and increase the pressure in a pipe segment extending to a dosing value. If a detection value of the exhaust gas temperature sensor is no greater than a predetermined temperature, and a detection value of the urea water sensor is no smaller than a freezing temperature, then the determination unit performs emptying control for returning the urea water from the pipe segment to the urea water tank to detect clogging of the pipe segment from the detection value of the pressure sensor.