Electric Traction Motor Cooling Circuit With Closed Pressure Equalization
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Solution Overview
Problem
Existing cooling systems for electric traction machines in motor vehicles experience impermissible pressure fluctuations due to temperature-induced volume changes in the coolant, leading to potential contamination from the environment.
Innovation Solution
A closed-loop cooling system with a gas-tight expansion tank connected to a volume equalization tank, which maintains pressure stability by allowing gas exchange without exposing the system to the environment, preventing contamination and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the cooling system is designed as a closed system with an expansion tank, then pressure stability is improved, but the system complexity increases due to additional components and connections
Solution Approach 1:
The cooling system is divided into two functionally independent parts: a closed cooling circuit for heat transfer and a separate gas-filled expansion tank for pressure equalization. This segmentation allows each component to perform its specific function optimally while minimizing interference between functions, thus improving pressure stability without requiring complex integration mechanisms.
Solution Approach 2:
The gas in the expansion tank serves as an intermediary element that absorbs pressure fluctuations from the closed cooling circuit. The compressible gas acts as a buffer between the coolant volume changes and the system pressure, equalizing pressure without requiring direct mechanical interaction between the coolant and external environment, thereby maintaining system simplicity.
2Stability of the object's composition
If the expansion tank is connected to the environment, then pressure equalization is improved, but contamination risk increases
Solution Approach 1:
The expansion tank is filled with an inert gas that creates a protective atmosphere, preventing contamination of the coolant while still allowing pressure equalization. The gas barrier isolates the coolant from external environmental contaminants while the gas itself remains compressible enough to perform pressure equalization functions.
Solution Approach 2:
The gas in the expansion tank acts as an intermediary medium that enables pressure equalization without direct contact between the coolant and the external environment. This intermediary layer prevents harmful factors from reaching the coolant while still allowing the system to respond to pressure changes.
3Productivity
If a dielectric coolant is used for direct cooling, then cooling efficiency is improved, but the risk of electrical insulation failure increases under high pressure conditions
Solution Approach 1:
The expansion tank with compressible gas provides beforehand cushioning against pressure fluctuations that could compromise the dielectric properties of the coolant. By absorbing pressure spikes before they reach critical levels, the system maintains the coolant's electrical insulation properties even during thermal expansion events, preventing insulation failure.
Solution Approach 2:
The system uses pneumatic principles with the gas-filled expansion tank to manage pressure in the hydraulic cooling circuit. The compressible gas provides a cushioning effect that protects the dielectric coolant from pressure-induced insulation breakdown while maintaining efficient heat transfer capabilities.
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 effectively manages pressure fluctuations and prevents coolant contamination, ensuring reliable temperature control and efficient heat dissipation in electric traction machines.
Implementation Method 1
an expansion tank (8) filled at least partially with the first coolant (5) to be circulated in the circuit system (4) and at least partially with a gas (9)... in which the coolant can carry out a volume equalization compared to a (slightly compressible) gas to equalize the pressure
Implementation Method 2
a first heat exchanger (12) for dissipating heat from and/or supplying heat to the first coolant (5) to be recirculated in the circuit system (4)
Data Source
AI summary
A cooling system for an electric traction machine for a motor vehicle includes a circuit system for conducting a first coolant to be circulated, a circulation pump for conveying the first coolant in the circuit system in a first circulation direction, and an expansion tank filled at least partially with the first coolant and at least partially with a gas. The cooling system also includes a motor input terminal for fluidically connecting the circuit system on an input side to the electric traction machine, a motor output terminal for fluidically connecting the circuit system on an output side to the electric traction machine, and a first heat exchanger for dissipating heat from and/or supplying heat to the first coolant. The expansion tank is exclusively connected on a gas side to at least one volume equalization tank which is closed gas-tight to an environment.