Engine Cooling Fan Reverse Operation During Hot Soak
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Solution Overview
Problem
Existing engine cooling systems waste energy by operating the cooling fan after engine shutdown, as heat from the engine can still transfer to the fuel tank, leading to fuel vapor generation and canister overloading, especially when the vehicle is parked on an incline, where heat naturally rises away from the fuel tank.
Innovation Solution
The engine cooling fan is adjusted to operate in a reverse direction after shutdown based on the elevation of the fuel tank relative to the engine, blowing air away from the engine and fuel tank, and its operation is controlled by a controller that considers engine temperature and vehicle grade to prevent unnecessary energy use and fuel vapor generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the engine cooling fan is operated after engine shutdown to cool the engine, then engine cooling is improved, but energy is wasted when heat naturally rises away from the fuel tank due to vehicle grade
Solution Approach 1:
The cooling fan operation is made dynamic and conditional rather than static and continuous. The controller activates the fan only when specific conditions are met (engine temperature above threshold AND fuel tank elevation below threshold), allowing the system to adapt to varying vehicle grades and thermal conditions, thereby eliminating unnecessary energy consumption while maintaining effective cooling when needed.
Solution Approach 2:
The system monitors and responds to changes in key parameters (engine temperature, fuel tank elevation relative to engine) to determine fan operation. By evaluating the relationship between these parameters and the vehicle grade, the controller adjusts fan operation to match actual thermal transfer conditions, preventing energy waste when gravitational effects naturally prevent heat transfer to the fuel tank.
2Temperature
If the engine cooling fan operates in reverse direction to draw air through the engine bay, then heat rejection from engine components is improved, but fuel vapor generation increases when the fuel tank is positioned above the engine
Solution Approach 1:
The fan operation mode (forward, reverse, or off) is dynamically selected based on real-time evaluation of engine temperature and fuel tank elevation. When the fuel tank is positioned above the engine, the controller prevents reverse fan operation that would draw hot air toward the fuel tank, thereby avoiding fuel vapor generation while still allowing forward fan operation or shutdown based on cooling needs.
Solution Approach 2:
The system applies different cooling strategies to different spatial configurations. When the fuel tank is above the engine, the control logic recognizes that heat naturally rises away from the fuel tank location, so reverse fan operation is avoided in this specific spatial arrangement. The solution tailors the cooling approach to the local geometric relationship between components rather than applying a uniform strategy.
3Temperature
If the engine cooling fan is operated continuously after shutdown, then maximum cooling effect is achieved, but unnecessary energy consumption occurs when heat transfer to fuel tank is prevented by vehicle grade
Solution Approach 1:
Instead of applying full cooling capacity continuously, the system applies partial cooling action only when and where needed. The controller evaluates whether heat transfer to the fuel tank is actually occurring based on vehicle grade and component elevation, and activates the fan only to the extent necessary to prevent harmful thermal transfer, rather than maintaining maximum cooling capacity at all times.
Solution Approach 2:
The system uses the vehicle's existing geometric configuration (fuel tank elevation relative to engine) and natural thermal convection patterns to determine when active cooling is necessary. When the fuel tank is positioned above the engine, the natural rising of hot air already prevents heat transfer to the fuel tank, making active fan operation unnecessary. The system leverages these self-service conditions to avoid wasted energy consumption.
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 reduces fuel vapor production and prevents canister overloading by ensuring that engine heat is not transferred to the fuel tank, thereby minimizing energy expenditure and emissions, while maintaining optimal engine and fuel tank temperatures.
Implementation Method 1
an engine cooling fan to cool the engine when the vehicle is stopped... operating an engine cooling fan to cool the engine when the vehicle is stopped
Implementation Method 2
heat from the hot engine persists or even increases and can transfer to the fuel tank
Implementation Method 3
heat from the engine naturally rises away from the fuel tank
Implementation Method 4
a carbon canister to adsorb fuel vapors resulting from refueling, diurnal temperature swings, heat rejection following engine shutdown, and running loss
Data Source
AI summary
Methods and systems are provided for cooling an engine. In one example, a method for an engine, includes, after an engine shutdown request is received, adjusting an engine cooling fan based on an engine temperature and an elevation of a fuel tank relative to the engine. In this way, fuel vapor generation may be prevented during an engine hot soak.