Battery Cooling via Drivetrain Oil Circulation
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Solution Overview
Problem
Conventional battery cooling systems require large refrigerant piping and compressors, leading to increased system size and inadequate heat exchange efficiency due to high thermal resistance between batteries and refrigerants.
Innovation Solution
A battery cooling system utilizing a drivetrain oil with electric insulation properties that circulates through a cooling circuit, directly exchanging heat with battery cells within a module case, eliminating the need for refrigerant piping and compressors, and enhancing cooling efficiency by optimizing flow pathways and component temperature management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If refrigerant piping is provided inside the sealed container to cool batteries, then cooling capability is provided, but the size of the sealed container increases
Solution Approach 1:
The invention extracts the cooling function from the sealed container by providing a separate cooling device with cooling fins that contact the outer surface of the container. This allows the container to maintain its original size while still achieving effective battery cooling through external heat dissipation structures.
Solution Approach 2:
The invention introduces a thermal coupling mechanism where cooling fins act as an intermediary between the battery container and the cooling medium. The fins transfer heat from the battery container surface to the cooling fluid or air, enabling efficient heat dissipation without requiring internal piping that would increase container size.
2Temperature
If refrigerant piping and compressor are used for battery cooling, then cooling function is achieved, but the entire system size increases
Solution Approach 1:
The invention extracts the complex refrigeration cycle components (compressor, refrigerant piping) and replaces them with a simplified cooling device that uses natural convection or simple fluid circulation. The cooling fins provide passive or active cooling without requiring bulky compression systems, significantly reducing overall system size.
Solution Approach 2:
The invention changes the cooling approach from active refrigerant-based cooling to a simpler heat exchange system using cooling fins and cooling fluid. This parameter change in the cooling mechanism eliminates the need for compressors and complex piping, reducing system size while maintaining cooling effectiveness.
3Temperature
If refrigerant flows through piping to exchange heat with batteries via silicon oil, then cooling is provided, but heat resistance is large and sufficient cooling capability is not achieved
Solution Approach 1:
The invention uses cooling fins as an intermediary structure that directly contacts the battery container surface, creating a large thermal contact area. This intermediary structure reduces thermal resistance by providing multiple heat transfer pathways from the battery surface to the cooling medium, significantly improving heat exchange efficiency and cooling capability.
Solution Approach 2:
The invention transitions from one-dimensional heat transfer through piping to three-dimensional heat dissipation using extended surface cooling fins. The fins create a large surface area in multiple dimensions, enabling more efficient heat exchange between the battery container and the cooling medium, thereby reducing thermal resistance and improving cooling performance.
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
The system achieves high cooling capability while reducing the size of the battery cooling system, effectively suppressing battery life degradation from heat and ensuring efficient cooling of both battery cells and power control units.
Implementation Method 1
The drivetrain oil flows through an inside of the module case and performs direct heat exchange with the battery cells
Implementation Method 2
a pump disposed in the cooling circuit, the pump supplying the drivetrain oil to the battery unit and circulating the drivetrain oil inside the cooling circuit
Implementation Method 3
a radiator disposed in the cooling circuit, the radiator releasing heat from the drivetrain oil flowing in the cooling circuit
Implementation Method 4
a radiator disposed in the cooling circuit, the radiator releasing heat from the drivetrain oil flowing in the cooling circuit
Data Source
AI summary
A battery cooling system includes: a cooling circuit; a power transmission device disposed in the cooling circuit, the power transmission device including a gear; a drivetrain oil having an electric insulating property and being used for lubrication of the gear, the drivetrain oil circulating in the cooling circuit; a battery unit disposed in the cooling circuit, the battery unit including a module case that houses a plurality of battery cells; a pump disposed in the cooling circuit; and a radiator disposed in the cooling circuit, the radiator releasing heat from the drivetrain oil flowing in the cooling circuit. The drivetrain oil performs direct heat exchange inside the power transmission device and flows through an inside of the module case and performs direct heat exchange with the battery cells.