Exhaust System Shutdown Control for DEF Dosing Unit Durability
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Solution Overview
Problem
Exhaust system components, particularly the diesel exhaust fluid (DEF) dosing unit, are susceptible to damage during engine shutdown due to trapped high temperatures during diesel particulate filter (DPF) regeneration, leading to potential component failure.
Innovation Solution
A controlled engine shutdown method that monitors exhaust system temperature and delays shutdown when it exceeds a threshold, aborts processes affecting temperatures, and allows operators to override the delay, ensuring sufficient cooling of heat-sensitive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engine shutdown is delayed to allow cooling of the DEF dosing unit, then component durability is improved, but shutdown time is increased
Solution Approach 1:
The control system predicts when an engine shutdown is likely to occur based on monitored states (gear selection, activity intervals, geographic position, time of day, fluid levels) and takes preliminary action by aborting DPF regeneration processes before the shutdown occurs. This prevents the DEF dosing unit from being exposed to high temperatures during shutdown, thereby protecting the component without actually delaying the shutdown itself.
Solution Approach 2:
The system continuously monitors exhaust system temperature and compares it against a threshold. When the temperature exceeds the threshold and a shutdown is predicted, the system provides feedback by aborting the DPF regeneration process. This closed-loop control ensures the DEF dosing unit is protected from thermal damage while maintaining efficient shutdown timing.
2Temperature
If DPF regeneration is aborted to cool the exhaust system, then component temperature is reduced, but regeneration effectiveness is lost
Solution Approach 1:
The control system applies preliminary anti-action by aborting the DPF regeneration process when it predicts an upcoming shutdown and detects high exhaust temperatures. This prevents the harmful effect of thermal damage to the DEF dosing unit before it can occur, rather than trying to mitigate the damage after it happens. The system prioritizes component protection over regeneration completion in this specific scenario.
Data Source
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AI summary
A controlled engine shutdown method is disclosed that includes monitoring exhaust system temperature, monitoring operator shutdown commands, and delaying engine shutdown based on exhaust system temperature. The method can include inhibiting any process that affects exhaust temperatures, for example DPF regeneration. The method can use a shutdown timer, allow operator override of the shutdown delay, and display a delay notification message. The method can also include predicting when an engine shutdown is expected, and delaying or aborting any process that would affect exhaust temperatures when an engine shutdown is predicted. Predicting can include monitoring various machine states, determining an average activity interval for the machine, determining a geographic shutdown area, determining a shutdown time of day and/or monitoring a machine fluid level.