Electric Drive Module Dual Sump Layout for Lower Gear Drag
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Solution Overview
Problem
Conventional thermal systems in battery electric vehicles (BEVs) inadequately manage coolant flow, leading to insufficient cooling and lubrication of electric drive modules (EDMs), resulting in higher operating temperatures, reduced efficiency, and increased aeration and foaming, which affect motoring performance and reliability.
Innovation Solution
A dual sump arrangement with a transfer gear mechanism that moves oil from a low sump to a high sump, reducing oil level in the gearbox and minimizing drag losses, combined with a controller to optimize coolant delivery based on motor speed and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional thermal system uses a single sump with high oil level to ensure sufficient cooling and lubrication, then cooling and lubrication are improved, but drag losses increase and aeration/foaming occurs
Solution Approach 1:
The single sump is divided into two separate sums: a first sump in the motor housing and a second sump in the gearbox housing. This segmentation allows independent oil level management in each region, enabling the gearbox to have reduced oil levels (lowering drag losses) while the motor housing maintains sufficient oil levels for adequate cooling and lubrication.
2Reliability
If a conventional thermal system uses a single sump with high oil level to ensure sufficient cooling and lubrication, then cooling and lubrication are improved, but aeration and foaming increase
Solution Approach 1:
By segmenting the single sump into two separate sums, the system isolates the gear meshing area (second sump) from the pump suction area (first sump). The reduced oil level in the second sump minimizes gear immersion and aeration, while the first sump maintains adequate oil levels for pump operation and cooling, thereby reducing overall aeration and foaming.
3Productivity
If the oil volume is set based on maximum flow rate requirement to ensure pump performance, then pump flow is improved, but unnecessary oil turnover causes excessive aeration and foaming
Solution Approach 1:
The segmentation allows the first sump to be optimized for pump suction with adequate oil levels for maximum flow rate requirements, while the second sump is optimized for minimal oil levels to reduce gear drag and aeration. This separate optimization enables the pump to achieve maximum flow rate without requiring excessive total oil volume that would cause aeration and foaming.
4Device complexity
If a single sump arrangement is used to simplify the system, then device complexity is reduced, but thermal management efficiency decreases
Solution Approach 1:
While the dual sump arrangement increases structural complexity compared to a single sump, it significantly improves thermal management efficiency by enabling independent optimization of oil levels in the motor housing and gearbox. The first sump ensures adequate cooling for the motor, while the second sump minimizes drag losses in the gearbox, achieving superior overall thermal management 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 dual sump configuration reduces drag losses and foaming, enhancing thermal management efficiency and performance by optimizing coolant flow, thereby improving motoring performance and reliability.
Implementation Method 1
Rotation of the transfer gear causes oil disposed in the second sump to be urged from the second sump, along the baffle and to the first sump
Implementation Method 2
Rotation of the transfer gear causes oil disposed in the second sump to be urged from the second sump, along the baffle and to the first sump effectively reducing an oil level in the gearbox housing and thereby reducing drag losses in the gearbox housing
Implementation Method 3
EDMs have electric motors that are cooled by thermal systems to prevent overheating
Implementation Method 4
a pump that delivers the coolant through a hydraulic circuit to the EDM
Data Source
AI summary
A thermal management system for an electric drive module (EDM) in an electric vehicle is provided. The system includes a motor housing, a gearbox housing, a sump and a baffle. The motor housing has an electric motor. The gearbox housing houses gears that receive an input from the electric motor and transfer the drive torque to the driveline. The sump collectively comprises a first sump and a second sump. The first sump is defined by first walls of the motor housing. The second sump is defined by second walls of the gearbox housing. The baffle is disposed in the sump. Rotation of a transfer gear causes oil disposed in the second sump to be urged from the second sump, along the baffle and to the first sump effectively reducing an oil level in the gearbox housing and thereby reducing drag losses in the gearbox housing.