Shielding Plate Sandwich Assembly for Motor EMC Containment
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Solution Overview
Problem
Existing electric drive units in motor vehicles suffer from electromagnetic interference radiation (EMC) emitted by electronic circuit boards and brush contacts, which can disrupt other electronic functions, and existing solutions fail to effectively shield these interferences across various installation positions.
Innovation Solution
An electric machine with an integrated electrically conducting shielding plate that forms a Faraday cage, providing comprehensive EMC shielding by being attached to the rotor bearing and stator housing, and utilizing a sandwich component configuration with preassembled shielding plates to minimize installation space and adapt to different variants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electronic circuit board with electronic components is arranged radially outside the pole housing, then different electronic functions can be realized with adaptability to installation positions, but electromagnetic interference radiation is emitted which disrupts other electronic functions
Solution Approach 1:
An electrically conducting shielding plate is introduced as an intermediary component between the electronic circuit board and the surrounding environment. The shielding plate is attached to the pole housing and extends into the transmission housing, creating a Faraday cage that blocks electromagnetic interference radiation while allowing the electronic circuit board to maintain its adaptable positioning for different installation configurations
Solution Approach 2:
The shielding solution is segmented into multiple parts: a first shielding plate attached to the pole housing, a second shielding plate attached to the transmission housing, and connecting elements that join these plates. This segmentation allows the shielding structure to be adapted to different installation positions and configurations while maintaining continuous electromagnetic protection
2Reliability
If brush contacts are arranged in the intermediate frame, then electrical contact function is achieved, but interference radiation is emitted which penetrates through the plastic transmission housing
Solution Approach 1:
The shielding plate acts as an intermediary barrier between the brush contacts and the external environment. By extending the shielding plate into the transmission housing and connecting it to the brush holder, the system maintains reliable electrical contact function while the shielding plate blocks interference radiation from penetrating through the plastic transmission housing
Solution Approach 2:
The shielding structure is nested within the existing housing and component arrangement. The shielding plate is integrated with the pole housing and transmission housing, and the brush holder is positioned within the shielded region, creating a nested configuration where the shielding plate protects the brush contacts while maintaining compact integration
3Device complexity
If a shielding plate is integrated into the brush holder and bearing plate as a sandwich component, then installation space is minimized and assembly is simplified, but the shielding plate must be electrically conducting over the full surface area to achieve effective EMC shielding
Solution Approach 1:
The shielding plate is merged with the brush holder and bearing plate to form an integrated sandwich component. This combining of functions reduces the number of separate parts and assembly steps while the shielding plate maintains continuous electrical conductivity over its full surface area, achieving both assembly simplification and effective EMC shielding
Solution Approach 2:
The shielding plate is made from electrically conducting material that combines structural and electromagnetic shielding functions. This composite approach allows the shielding plate to serve multiple purposes: providing mechanical support as part of the sandwich component structure while simultaneously achieving uniform electrical conductivity across its surface for effective EMC protection
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
The solution effectively shields electromagnetic interference radiation up to high frequencies (3 GHz) while maintaining a compact and mechanically stable design, ensuring reliable operation across various installation configurations and customer-specific requirements.
Implementation Method 1
Together with the shielding plate, the stator housing forms a Faraday cage which, as an EMC shielding means, shields the electromagnetic interference radiation which is produced to the outside
Implementation Method 2
The shielding plate can be attached to the rotor bearing by means of a large electric ground contact over the full surface area
Data Source
AI summary
An electric machine (10), in particular for the adjustment of movable parts in the motor vehicle, includes a stator housing (22) which receives a stator (12) and a rotor (14), the rotor (14) having a rotor shaft (16), on which a commutator (18) is arranged and which can be energized by electric brushes (20), and the stator housing (22) having an axial opening (24), through which the rotor shaft (16) protrudes out of the stator housing (22), an electrically conducting shielding plate (29) being inserted axially between a brush holder plate (55) and a bearing plate (56) for the rotor shaft (16) in order to form a sandwich component (70), the sandwich component (70) extending transversely with respect to the rotor shaft (16) and covering substantially the entire opening (24).