Vehicle Cooling Loop Layout for Direct-Cooled E-Motor and Transmission
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Solution Overview
Problem
Existing motor vehicles face challenges in efficiently cooling both the electric machine and transmission while maintaining a compact design.
Innovation Solution
A cooling system with three interconnected loops: a first loop for directly cooling the electric machine using dielectric coolant, a second loop for cooling the transmission using transmission oil, and a third loop for cooling other components using a third coolant, with heat exchangers connecting the first and third loops and the second and third loops, and tandem pumps for efficient coolant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate cooling loops are used for the electric machine and transmission, then cooling efficiency is improved, but system complexity increases
Solution Approach 1:
The patent combines multiple cooling functions into a single integrated cooling loop that serves both the electric machine and transmission. The coolant flows through both components sequentially, allowing heat to be extracted from both sources without requiring separate closed-loop systems. This merging approach maintains effective cooling while significantly reducing system complexity compared to fully separate cooling loops.
Solution Approach 2:
The single cooling loop is designed to perform multiple functions: cooling the electric machine, cooling the transmission, and potentially cooling other components. The coolant circuit is configured to flow through multiple heat-generating components, allowing one cooling system to serve universal cooling needs across different powertrain components, thereby avoiding the complexity of multiple dedicated cooling systems.
2Volume of moving object
If a compact cooling system design is implemented, then vehicle space is reduced, but cooling effectiveness may be compromised
Solution Approach 1:
By merging the cooling of the electric machine and transmission into a single loop, the patent eliminates the need for separate coolant reservoirs, pumps, and routing for each component. This consolidation significantly reduces the overall volume required for the cooling system while maintaining the ability to effectively cool both components through optimized coolant flow paths.
3Device complexity
If the same coolant is used for both electric machine and transmission, then system complexity is reduced, but coolant compatibility issues arise
Solution Approach 1:
The patent specifies using a water-glycol mixture as the coolant, which has particular properties that make it suitable for both electric machine cooling and transmission cooling. By carefully selecting and specifying the coolant composition (parameter change), the system achieves compatibility across different components without requiring separate cooling systems, thus reducing complexity while maintaining reliability.
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
Enables efficient cooling of both the electric machine and transmission with a compact design, reducing cable lengths and improving heat dissipation.
Implementation Method 1
The first cooling loop and the third cooling loop are coupled via a first heat exchanger, and the second cooling loop and the third cooling loop are coupled via a second heat exchanger
Data Source
AI summary
A motor vehicle including a drive unit with an electric machine, wherein the electric machine is a directly cooled electric machine, a transmission, a first cooling loop for cooling assemblies of the directly cooled electric machine using a first dielectric coolant which flows directly around respective assemblies of the electric machine, a second cooling loop for cooling the transmission using a second coolant designed as a transmission oil, and a third cooling loop using a third coolant. The first cooling loop and the third cooling loop are coupled via a first heat exchanger, and the second cooling loop and the third cooling loop are coupled via a second heat exchanger.