Electric Machine Wet-Dry Seal via Composite Connection
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Solution Overview
Problem
Existing electric machines for motor vehicle drive trains face challenges in achieving safe and cost-effective electrical and mechanical contact between wet and dry sides, particularly in high-power density applications, where hydraulic fluids are used for cooling, leading to limitations in both electrical conductivity and mechanical load-bearing capacity.
Innovation Solution
The electric machine design incorporates an electric connection element with a contacting body and a receiving sleeve, where the contacting body, made of a material with higher mechanical strength, supports clamping forces, and the receiving sleeve, made of a softer material with higher specific electrical conductivity, facilitates current flow, ensuring effective sealing and assembly through a press fit and additional sealing elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single material is used for the electric connection element to provide both mechanical strength and electrical conductivity, then the structure is simple, but the performance is limited due to the trade-off between mechanical load-bearing capacity and electrical conductivity
Solution Approach 1:
The electric connection element is designed as a composite structure consisting of a contacting body and a receiving sleeve made of different materials. The contacting body is made of a material with higher mechanical strength to support clamping forces, while the receiving sleeve is made of a softer material with higher specific electrical conductivity to facilitate current flow. This composite material approach resolves the contradiction by allowing each component to be optimized for its primary function.
Solution Approach 2:
The electric connection element is segmented into two distinct components: a contacting body and a receiving sleeve. This segmentation allows each part to be made from materials optimized for its specific function - the contacting body for mechanical strength and the receiving sleeve for electrical conductivity. The segmented structure enables independent optimization of each component's material properties.
2Temperature
If hydraulic fluid is used for cooling in high-power density applications, then cooling capacity is improved, but the complexity of maintaining safe electrical and mechanical contact between wet and dry sides increases
Solution Approach 1:
The electric connection element serves as an intermediary component that bridges the wet side (hydraulic fluid side) and the dry side (electrical side). The receiving sleeve with its sealing function acts as a mediator that allows hydraulic fluid to cool the stator winding while preventing fluid leakage and maintaining electrical isolation. This intermediary structure enables effective cooling while managing the complexity of interfacing between fluid and electrical systems.
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 provides a robust and efficient electrical and mechanical connection, enhancing the power density and reliability of the electric machine while maintaining a high level of electrical conductivity and mechanical strength, thus addressing the limitations of existing technologies.
Implementation Method 1
the softer material is elastically and plastically deformed so that the sealing effect is sufficient
Implementation Method 2
the softer material is elastically and plastically deformed so that the sealing effect is sufficient
Data Source
AI summary
An electric machine, for an electric drive train in a motor vehicle, includes a rotor rotatably mounted relative to a stator, the stator having a first stator member with a first stator winding arranged within a first chamber, at least part of which is enclosed by a delimiting first casing component. The first casing component contains an electric connection element with a contacting member and a reception sleeve which extend therethrough such that a first portion of the reception sleeve protrudes into the first chamber and a second portion of the contacting member is contactable from the side of the first casing component facing away from the first chamber. The contacting member is secured in the reception sleeve, which is accommodated in the first casing component. The contacting body is fixed in the receiving sleeve, which is received in the first housing component.