Extended Surface Cooler for Electric Machine Internal Cooling
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Solution Overview
Problem
Existing electric machines, particularly those used as axle drives in vehicles, face challenges in efficiently dissipating heat due to complex and costly cooling systems, which are insufficient for high-power applications with limited installation space.
Innovation Solution
A structurally simple and cost-effective liquid cooling system is implemented using a ring segment-shaped extended surface cooler connected to the housing, allowing for direct cooling of internal components without additional heat-conducting elements, leveraging existing liquid cooling systems and enabling efficient heat dissipation through a ring-segment flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a jacket cooling system is used for the stator, then the stator can be cooled effectively, but the cooling of internal components becomes structurally complex
Solution Approach 1:
The housing wall serves dual functions: it provides structural support for the electric machine and acts as a heat conduction path for the extended surface cooler. By integrating the cooling function into the existing housing structure, the system achieves multi-functionality without adding separate cooling infrastructure, thereby reducing overall system complexity while maintaining effective cooling of both stator and internal components.
Solution Approach 2:
The cooling system is segmented into two distinct but integrated parts: the jacket cooling system for the stator and the extended surface cooler for internal components. This segmentation allows each cooling mechanism to be optimized for its specific target while sharing the common coolant infrastructure, reducing complexity compared to a fully integrated complex cooling system.
2Temperature
If additional heat-conducting elements are added for internal component cooling, then cooling effectiveness improves, but manufacturing cost and structural complexity increase
Solution Approach 1:
The extended surface cooler is merged with the housing wall to form an integrated cooling structure. The housing wall itself becomes the heat conduction element, eliminating the need for separate, complex heat-conducting components. This merging reduces manufacturing steps, lowers material costs, and simplifies assembly while achieving effective direct cooling of internal components like rotor windings and bearings.
Solution Approach 2:
The housing wall performs the dual service of providing structural support and acting as a heat conduction path for cooling. By utilizing the existing housing structure for cooling purposes, the system eliminates the need for additional dedicated heat-conducting elements, thereby reducing manufacturing complexity and cost while achieving effective cooling.
3Temperature
If a complex cooling system is used for high-power applications, then cooling effectiveness improves, but installation space requirements increase
Solution Approach 1:
The extended surface cooler utilizes the housing wall surface area as a two-dimensional heat conduction path, transforming the cooling approach from volumetric (requiring internal cooling channels) to surface-based. This dimensional change allows effective cooling of internal components without occupying additional installation space, as the cooling function is embedded in the existing housing structure rather than requiring separate volumetric cooling components.
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 solution effectively cools both the stator and internal components, such as rotor windings and bearings, by directly absorbing and dissipating heat, optimizing performance and reducing complexity and cost in electric machines used in vehicles.
Implementation Method 1
an extended surface cooler (10), or the like, which is connected to the liquid cooling via the housing wall, is provided in the interior of the housing for the direct cooling of components arranged in the interior of the housing
Implementation Method 2
a ring-segment flow in the interior of the housing around the rotor axis is made possible and, therefore, the surrounding components are effectively cooled
Implementation Method 3
the emitted heat is directly absorbed and particularly effectively dissipated by the coolant
Data Source
AI summary
An electric machine includes a stator (1) and a rotor (2), which are arranged in a housing (3). A liquid cooling jacket is configured for cooling the stator (1). At least one extended surface cooler (10), which is connected to the liquid cooling jacket via a housing wall, is provided in an interior of the housing (3) for direct cooling of components arranged in the interior of the housing (3). Moreover, an axle drive of a vehicle may include the electric machine.