CCV Stuck-Open Fault Detection via DEF-Ambient Temperature Divergence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Diesel engines with Selective Catalytic Reduction (SCR) systems face challenges in quickly thawing Diesel Emissions Fluid (DEF) during cold weather without exposing the Urea Quality Sensor (UQS) and DEF to elevated temperatures, especially when the Coolant Control Valve (CCV) becomes stuck open or partially open, failing to trigger a fault at the standard 75°C threshold.
Innovation Solution
Implementing a control logic that monitors the divergence between ambient and DEF tank temperatures, triggering a CCV stuck open fault when the temperature difference exceeds a set threshold for a specific period, ensuring controlled thawing and protecting the UQS and DEF from excessive heat, even if the DEF tank temperature does not reach 75°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the Coolant Control Valve (CCV) remains open during cold weather thawing, then the DEF tank temperature increases and thawing speed improves, but the UQS and DEF are exposed to elevated temperatures causing accelerated aging and decomposition
Solution Approach 1:
The control module continuously monitors DEF tank temperature and compares it against a threshold (e.g., 60°C or 65°C) that is lower than the traditional 75°C stuck-open threshold. When the temperature exceeds this lower threshold, the system triggers a stuck-open fault condition, closing the CCV to prevent further temperature rise and protect the UQS from thermal degradation
Solution Approach 2:
The system proactively triggers a stuck-open fault condition before the DEF temperature reaches levels that would cause significant UQS degradation. By using a lower temperature threshold (60-65°C) compared to the traditional 75°C, the system prevents harmful thermal effects on the UQS and DEF before they can occur, rather than waiting for damage to manifest
2Reliability
If the CCV stuck open threshold is set at 75°C, then false positives are reduced, but the UQS is still exposed to temperatures between 60-75°C causing accelerated aging without triggering a fault
Solution Approach 1:
The system changes the temperature parameter threshold from the traditional 75°C to a lower value (60°C or 65°C) that better protects the UQS. This parameter adjustment creates a new operational boundary that prevents thermal degradation while maintaining reliable fault detection through continuous monitoring and comparison against the updated threshold
3Reliability
If the CCV is closed to maintain low DEF temperature, then UQS protection is improved, but the thawing time increases significantly in cold weather
Solution Approach 1:
The CCV operates dynamically with different positions during different phases of operation: fully open during initial thawing to maximize heat transfer and reduce thawing time, and fully closed when the DEF temperature approaches the threshold to prevent overheating. This dynamic control optimizes both thawing speed and UQS protection throughout the operational cycle
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 extends the life of the UQS by preventing accelerated aging due to elevated temperatures and reduces DEF degradation, ensuring efficient SCR system operation by maintaining optimal DEF temperatures.
Implementation Method 1
heat from the engine, often by way of engine coolant passing through a heat exchanger in the DEF tank
Implementation Method 2
the frozen DEF in the DEF tank must be melted in as short time as possible
Data Source
AI summary
A Diesel Emissions Fluid (DEF) Thawing arrangement and method is provided for use with a vehicle having an engine, an Engine Control Module (ECM), an exhaust system, and a Selective Catalyst Reduction (SCR) catalytic device. A DEF injection system is connected to the exhaust system and to the ECM. A DEF tank is connected to the DEF injection system, and is provided with a Urea Quality Sensor (UQS). A coolant loop is connected to the engine and has a Coolant Control Valve (CCV) connected to a control module, and a coolant to DEF heat exchanger. A DEF temperature sensor and an ambient temperature sensor are connected to the control module. The control module is configured to trigger a CCV stuck open fault when the DEF tank temperature exceeds the ambient temperature by a threshold amount for a period of time.