Shielded Rotation Transmission Shaft for High-Torque EMC Testing
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Solution Overview
Problem
Existing rotation transmission mechanisms face challenges in achieving high-speed rotation with high torque transmission while maintaining effective electromagnetic shielding, especially in EMC testing environments where long shafts are required and electromagnetic noise interception is crucial.
Innovation Solution
A rotation transmission device featuring a conductive rigid cylinder with bearings at both ends, supporting a shaft made of conductive fiber-reinforced plastic, which allows for high-speed rotation up to 16,000 rpm and high torque transmission, while maintaining electromagnetic shielding through conductive resin fiber brushes and electrical conduction between the shaft and the rigid cylinder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a long shaft is used to connect the motor inside the electromagnetic anechoic chamber to the load motor outside, then the mechanical connection requirement is met, but the shaft experiences skipping rope phenomenon and deflection at high rotation speeds
Solution Approach 1:
The patent employs a composite shaft structure consisting of an inner shaft and an outer shaft made of different materials with complementary properties. The inner shaft provides torsional rigidity while the outer shaft provides bending rigidity, allowing the long shaft to maintain stability at high rotation speeds without experiencing skipping rope phenomenon or excessive deflection.
2Power
If a metal shaft is used for rotation transmission, then high torque and high-speed rotation are achieved, but electromagnetic noise leaks through the shaft penetrating the anechoic chamber wall
Solution Approach 1:
The patent introduces electromagnetic shielding plates and shielding structures as intermediaries between the metal shaft and the external environment. These shielding components intercept electromagnetic noise generated by the motor inside the anechoic chamber, preventing it from leaking through the shaft penetration point while allowing mechanical torque transmission to continue uninterrupted.
3Ease of operation
If the shaft penetrates through the electromagnetic anechoic chamber wall, then mechanical connection between inside and outside motors is achieved, but electromagnetic wave shielding is compromised
Solution Approach 1:
The patent implements a nested shielding structure where multiple shielding components are arranged concentrically around the shaft penetration point. The shielding plates, conductive seals, and magnetic shielding layers are nested within each other, creating multiple barriers that collectively block electromagnetic waves while accommodating the shaft's mechanical connection function.
4Ease of manufacture
If conventional EMC testing is conducted with the motor in idle state, then testing simplicity is maintained, but the testing does not reflect actual automobile running conditions
Solution Approach 1:
The patent employs a dynamic test bench system that can adjust the rotation speed and load conditions of the motor under test to simulate various actual automobile running states. The test bench includes controllable loading mechanisms and variable speed drives, allowing researchers to transition from simple idle state testing to complex dynamic driving condition testing, thereby improving testing accuracy while maintaining operational simplicity through automated control.
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 enables accurate centering of the rotation shaft, prevents the skipping rope phenomenon, and effectively shields electromagnetic waves, allowing for high-speed, high-torque rotation transmission while adhering to international EMC testing standards.
Implementation Method 1
a shaft made of conductive fiber-reinforced plastic supported by the bearings, where the shaft length is 900 mm or longer, and high speed rotation of 16,000 revolutions per minute (r.p.m.) or more is achieved
Implementation Method 2
electromagnetic wave shielding is made by conductive resin fiber brushes which obstruct the space by being contact with the shaft periphery at both ends of the conductive rigid cylinder
Implementation Method 3
electrical conduction between the shaft and the rigid cylinder
Implementation Method 4
bearings provided at both ends parts of the conductive rigid cylinder
Data Source
AI summary
During EMC testing of electric motors, a rotation transmission device that penetrates a wall in an electromagnetic anechoic chamber has been unable to achieve high rotation and high torque, because of the skipping rope phenomenon. In order to achieve rotation transmission at high rotation and high torque, a fiber-reinforced plastic shaft is supported by a bearing inside a conductive housing; and a conductive brush that obstructs a space between the housing and the shaft surface is provided so as to provide electrical conduction between the housing and the shaft and prevent radio wave leakage. A plurality of bearings could be used, excluding at both ends, in order to achieve rotation transmission at high rotation and high torque.