Immersion-Cooled Drive Unit Layout for Compact Coil Cooling
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Solution Overview
Problem
Existing drive units for electric vehicles face challenges in achieving a compact upper-lower dimension while maintaining effective cooling efficiency for the coil.
Innovation Solution
The drive unit incorporates a stator immersed in a cooling fluid within a motor chamber, with a separator positioned between the cooling fluid discharge portion and the stator. This configuration allows the cooling fluid to flow through a communication space and be discharged efficiently, ensuring the coil is fully immersed and cooled effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cooling fluid discharge port is provided in the upper portion of the case protruding upward, then the cooling fluid can be discharged effectively, but the upper-lower dimension of the motor unit is increased
Solution Approach 1:
The cooling fluid discharge port is relocated from the upper portion (vertical dimension) to the front or rear wall (horizontal dimension). This dimensional shift allows the port to be positioned at a lower height, reducing the upper-lower dimension of the motor unit while maintaining effective cooling fluid discharge through the side walls rather than the top.
2Length of stationary object
If the cooling fluid discharge port is provided in the horizontal walls, then the upper-lower dimension is reduced, but the cooling fluid cannot be sufficiently discharged and coil cooling efficiency is lowered
Solution Approach 1:
A cooling fluid circulation path is introduced as an intermediary mechanism. The path includes a discharge port in the horizontal wall connected to a discharge passage that extends upward behind the partition wall to the upper interior space. This intermediary pathway allows the cooling fluid to be discharged horizontally at a low position while still reaching the upper cooling zone, thus maintaining cooling efficiency without increasing the external upper-lower dimension.
3Loss of energy
If a partition wall is introduced to separate cooling fluid and rotor, then energy loss is reduced, but the cooling fluid flow path becomes more complex
Solution Approach 1:
The partition wall is designed to serve multiple functions simultaneously: (1) separating the cooling fluid from the rotor to reduce energy loss, (2) providing structural support for the cooling fluid introduction and discharge ports, (3) creating defined flow paths for cooling fluid circulation, and (4) maintaining the air gap between rotor and stator. By consolidating these functions into a single structural element, the overall complexity is managed while achieving the desired separation and 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
This design enables a compact upper-lower dimension for the drive unit without compromising the cooling efficiency of the coil, allowing for efficient power transmission and reduced energy loss.
Implementation Method 1
the stator is immersed in the cooling fluid introduced into the motor chamber through the cooling fluid introduction portion to be cooled by the cooling fluid
Data Source
AI summary
A drive unit has a drive motor, and a drive unit case having a motor chamber accommodating the drive motor. The drive unit case has an introduction portion and a discharge portion of a cooling fluid. A stator of the drive motor is immersed in the cooling fluid introduced into the motor chamber. The discharge portion is provided in a wall oriented in a horizontal direction of the motor chamber. The motor chamber is provided with a separator at a position between the discharge portion and the stator. The separator extends in an upper-lower direction such that an upper end of the separator is positioned higher than an upper end of a coil of the drive motor. A communication space is formed between the upper end of the separator and the drive unit case. The cooling fluid is discharged to an outside of the motor chamber through the communication space.