DEF Injector Cooling System Post-Shutdown Thermal Management
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Solution Overview
Problem
High temperatures in diesel engine systems can damage or cause suboptimal performance of diesel exhaust fluid (DEF) injectors used in selective catalytic reduction (SCR) systems, as they are not effectively cooled.
Innovation Solution
A DEF injector cooling system comprising a mechanical pump, an electric pump, and a controller that powers the electric pump after engine shutdown based on ambient and exhaust temperatures to circulate coolant through the DEF injector, maintaining it below a damaging temperature threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only a mechanical pump driven by the engine is used to cool the DEF injector, then the cooling system is simple and energy-efficient during operation, but the DEF injector cannot be cooled after engine shutdown when temperatures remain high
Solution Approach 1:
The mechanical pump serves dual functions: it cools the DEF injector during engine operation by circulating coolant, and can be supplemented by an electric pump for post-shutdown cooling. This multi-functionality allows the system to address thermal protection needs across different operational states without requiring completely separate cooling systems for each mode.
Solution Approach 2:
A temperature sensor acts as an intermediary between the thermal environment and the control system. It monitors the DEF injector temperature and provides feedback to the controller, which then activates the electric pump when cooling is needed after shutdown. This intermediary enables automatic, condition-based cooling activation without complex direct temperature-to-control-linkage.
2Reliability
If an electric pump is added to provide post-shutdown cooling, then the DEF injector is effectively cooled after engine shutdown, but the system complexity and energy consumption increase
Solution Approach 1:
The electric pump operates periodically rather than continuously - it is activated only when the engine shuts down and the DEF injector temperature exceeds a threshold, and deactivated when the temperature drops below a threshold. This periodic operation significantly reduces energy consumption compared to continuous operation while still providing necessary cooling protection during the critical post-shutdown period.
Solution Approach 2:
The controller uses feedback from the temperature sensor to automatically control the electric pump operation. When the sensor detects high DEF injector temperature after shutdown, the controller activates the electric pump; when temperature drops to acceptable levels, the controller deactivates it. This feedback-based control ensures the pump runs only when necessary, minimizing energy consumption while maintaining reliable thermal protection.
3Reliability
If the electric pump runs continuously to ensure adequate cooling, then the DEF injector temperature is maintained below critical levels, but energy consumption and system complexity increase unnecessarily
Solution Approach 1:
The electric pump operates periodically rather than continuously - it is activated only when the engine shuts down and the DEF injector temperature exceeds a threshold, and deactivated when the temperature drops below a threshold. This periodic operation significantly reduces energy consumption compared to continuous operation while still providing necessary cooling protection during the critical post-shutdown period.
Solution Approach 2:
The controller uses feedback from the temperature sensor to automatically control the electric pump operation. When the sensor detects high DEF injector temperature after shutdown, the controller activates the electric pump; when temperature drops to acceptable levels, the controller deactivates it. This feedback-based control ensures the pump runs only when necessary, minimizing energy consumption while maintaining reliable thermal protection.
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
Effectively cools the DEF injector, preventing damage and ensuring optimal performance by maintaining the injector below a critical temperature, even after engine shutdown, thereby extending its lifespan and maintaining system efficiency.
Implementation Method 1
The mechanical pump may be fluidly connected to the engine, a DEF injector, and a heat exchanger, and configured to pump coolant through these components
Implementation Method 2
The electric pump may be fluidly connected to the DEF injector and configured to pump coolant through it
Implementation Method 3
The mechanical pump may be fluidly connected to the engine, a DEF injector, and a heat exchanger, and configured to pump coolant through these components
Data Source
AI summary
A DEF injector cooling system may include a mechanical pump, an electric pump, and a controller. The mechanical pump may be rotatably coupled to an engine so as to be driven by the engine. The mechanical pump may be fluidly connected to the engine, a DEF injector, and a heat exchanger, and configured to pump coolant through these components. The electric pump may be fluidly connected to the DEF injector and configured to pump coolant through it. The controller may be configured to receive an ambient temperature signal indicative of an ambient temperature and power the electric pump after a shutdown of the engine for a period of time, the duration of the period of time based on the ambient temperature signal.