Open Expansion Tank Venting for Traction Motor Cooling Pressure Stability
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Solution Overview
Problem
Existing cooling systems for electric traction machines in motor vehicles face issues with pressure fluctuations due to temperature changes, leading to impermissible high or low operating pressures, which can affect the efficiency and reliability of the cooling process.
Innovation Solution
The cooling system incorporates an open expansion tank that allows for gas exchange with the environment to compensate for volume changes in the coolant, using a semi-open design with a calming section and adsorption filters to manage pressure and prevent contamination, ensuring that pressure fluctuations remain within safe limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an expansion tank is provided to compensate for volume changes in the coolant, then pressure fluctuations are reduced, but the system complexity increases
Solution Approach 1:
The expansion tank is integrated into the existing cooling circuit as a combined component that serves multiple functions: it compensates for coolant volume changes, provides gas separation, and maintains system pressure. This merging approach allows the expansion tank to address pressure stability issues without requiring entirely separate compensation systems, thereby reducing overall system complexity while improving reliability.
2Reliability
If the expansion tank is designed open to the environment, then volume fluctuations are better compensated, but contamination risk increases
Solution Approach 1:
A breathing filter is introduced as an intermediary component between the expansion tank interior and the external environment. This filter allows air exchange necessary for volume compensation while simultaneously blocking contaminants, moisture, and debris from entering the system. The breathing filter thus mediates between the conflicting requirements of open design for volume compensation and closed design for contamination prevention.
3Reliability
If the gas outlet is directly open to the environment, then pressure relief is improved, but adsorption filters are overloaded
Solution Approach 1:
The gas outlet path is segmented into multiple functional zones: a breathing filter for initial filtration, a calming section for flow stabilization and droplet separation, and then discharge to the environment. This segmentation allows pressure relief to occur while distributing the filtration load appropriately, preventing overload of any single filter component while maintaining effective contamination barriers.
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 design effectively stabilizes pressure within the cooling system, enhancing the efficiency of heat dissipation and preventing damage from pressure extremes, while also reducing the load on adsorption filters and extending their service life.
Implementation Method 1
whereby preferably by means of the calming section, liquid can be separated from a gas stream passing through the calming section via a calming labyrinth
Implementation Method 2
liquid can be separated from a gas stream passing through the calming section via a calming labyrinth
Implementation Method 3
an adsorption filter for filtering passing air
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a cooling system (1) for an electric traction motor (2) for a motor vehicle (3), comprising at least the following components: - a circulating system (4) for conveying a first circulating coolant (5); - a circulating pump (6) for pumping the first coolant (5) in the circulating system (4) in a first circulating direction (7); - an expansion tank (8) which is at least partially filled with the first coolant (5) to be circulated in the circulating system (4) and at least partially filled with a gas (9); - a motor inlet connection (10) for fluidically connecting the circulating system (4) to an electric traction motor (2) to be cooled on the inlet side; - a motor outlet connection (11) for fluidically connecting the circulating system (4) to the electric traction motor (2) to be cooled on the outlet side;and - a first heat exchanger (12) for removing heat from and/or supplying heat to the first coolant (5) circulating in the circuit system (4). The cooling system (1) is characterized in particular by the fact that the expansion tank (8) is open to the environment (14) via an opening (13). Efficient venting of the coolant is possible with the expansion tank and cooling system proposed here.