Vehicle Electric Machine Rotor Cooling With Separate Heat Path
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Solution Overview
Problem
Conventional electric machines face challenges in effectively cooling the rotor while maintaining structural integrity and controlling costs, as high thermal conductivity materials are expensive and require thick structures to handle bearing forces, which hinders heat dissipation.
Innovation Solution
The rotor is mounted directly on the housing end plates via a bearing device, allowing for a heat transmission body with thin walls and high thermal conductivity, separate from the housing parts, enabling efficient heat transfer and cost savings by using lower thermal conductivity materials for the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a structure with high thermal conductivity is used to take up heat from the rotor, then heat dissipation is improved, but production costs increase significantly
Solution Approach 1:
The housing is divided into two separate parts: the heat transmission body made of high thermal conductivity material and the housing parts made of lower thermal conductivity material. This segmentation allows each component to be optimized for its specific function while using appropriate materials, resolving the contradiction between heat dissipation performance and production costs.
2Strength
If the structure near the rotor is made solid to handle bearing forces, then structural integrity is improved, but heat dissipation capability deteriorates
Solution Approach 1:
The bearing support function and heat dissipation function are separated into different components. The housing parts provide structural support for bearing forces, while the separate heat transmission body provides the heat dissipation pathway. This functional segmentation resolves the contradiction between structural integrity and heat dissipation capability.
Solution Approach 2:
The heat transmission body acts as an intermediary component between the rotor and the housing parts. It receives heat from the rotor through direct contact and transfers it to the coolant, while the housing parts provide structural support. This intermediary structure allows both bearing force support and effective heat dissipation without requiring the structural components to have high thermal conductivity.
3Strength
If a thick-walled structure is used to support bearing forces, then mechanical strength is improved, but heat transmission efficiency deteriorates
Solution Approach 1:
The structural support function and heat transmission function are assigned to separate components with different wall thicknesses. The housing parts have thick walls for mechanical strength, while the heat transmission body has thin walls for high heat transmission efficiency. This segmentation resolves the contradiction between mechanical strength and heat transmission efficiency.
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 configuration enhances heat transfer efficiency and reduces production costs by allowing the use of less expensive materials for the housing while maintaining effective cooling of the rotor, avoiding overheating and material wastage.
Implementation Method 1
a heat transmission body which, in order to take up waste heat from the stator, is arranged between a coolant path which is provided in the housing—and can be embodied as a cooling duct, coolant collector or coolant collector—and the rotor in the housing interior
Data Source
AI summary
An electric machine for a vehicle is disclosed. The electric machine includes a stator and a rotor rotatable relative to the stator about a rotational axis that defines an axial direction. A housing at least partially surrounds a housing interior and includes a first housing part and a second housing part that bound the housing interior. The rotor is rotatably mounted on the first housing part and the second housing part via a bearing device. At least one heat transmission body is arranged along the axial direction between at least one of the first and second housing parts and the rotor. The heat transmission body bounds, together with the at least one of the first and second housing parts, a coolant space through which a coolant can flow.