Resonant Shield for Rotary Joint Stray Field Cancellation
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Solution Overview
Problem
Existing rotary joints for transferring electrical signals between rotating parts face challenges in achieving compactness, reliability, and affordability while minimizing electromagnetic interference and stray fields, which affect data transmission quality.
Innovation Solution
A compact rotary joint design incorporating inductive power transfer, capacitive data transfer, and resonant shielding with open ring structures to cancel stray fields, allowing for high data rate transmission and reduced interference, using magnetic cores with ferrite or iron materials and a galvanic slipring connection to minimize magnetic field interference with capacitive data links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a wide bandwidth shield is used to reduce stray fields from sensitive electronic components, then electromagnetic interference is reduced, but unwanted energy is not absorbed and may radiate signals from capacitive data links
Solution Approach 1:
The patent introduces resonant circuits that convert the harmful wide bandwidth shield into a beneficial frequency-selective structure. By tuning the resonant frequency to match the capacitive data link frequency, the shield structure absorbs unwanted energy at specific frequencies while maintaining transparency at other frequencies, thus converting the harmful radiation into beneficial energy absorption.
Solution Approach 2:
The patent changes the electrical parameters of the shield by incorporating resonant circuits with specific inductance and capacitance values. This transforms the shield from a passive wide bandwidth structure to an active frequency-selective structure that can differentiate between power transfer frequencies and data link frequencies, absorbing only the unwanted data link signals.
2Volume of moving object
If capacitive couplers are arranged partially within the magnetic cores to save space, then compactness is improved, but electromagnetic interference between power transfer and data transfer increases
Solution Approach 1:
The patent utilizes the magnetic core structure not only for power transfer but also incorporates resonant circuits within or around the magnetic cores to absorb stray fields. This converts the potentially harmful electromagnetic interference generated by the compact arrangement into beneficial field absorption, maintaining both compactness and electromagnetic compatibility.
Solution Approach 2:
The patent nests the capacitive couplers within the magnetic core structure, placing data transfer components inside or around the power transfer magnetic cores. This nested arrangement maximizes space utilization while the resonant circuits embedded in the same structure provide frequency-selective shielding to prevent interference between the nested 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
The solution effectively cancels over 50% of stray fields, ensuring reliable and efficient high-data-rate transmission with reduced electromagnetic interference, maintaining compactness and affordability.
Implementation Method 1
at least one resonant shield is provided outside the airgap of the magnetic core. Each resonant shield comprises an open ring shaped structure, having two open ends which are coupled to and connected by a capacitor to form a resonant circuit. The resonance frequency is determined by the inductance of the ring shaped structure and the capacitance. This resonant circuit may have a resonance frequency which is at an operation frequency of the first and second magnetic core or multiples thereof.
Implementation Method 2
The first magnetic core (210) may have a first winding (212), and the second magnetic core (310) may have a second winding (312). The first winding (212) and the second winding (312) may be magnetically coupled with each other through the first magnetic core (210) and the second magnetic core (310).
Implementation Method 3
The first part may have a first capacitive data link component (270), and the rotary joint may have a second capacitive data link component (370).
Data Source
AI summary
A rotary joint includes a first part and a second part configured to rotate around a rotation axis against the first part. The first part has a first magnetic core and a capacitive data link component. The second part has a second magnetic core for coupling power with the a first magnetic core and a second capacitive data link component to transfer data from and/or to the first capacitive data link component. To weaken magnetic stray fields from the magnetic core, a resonant shield is provided outside the airgap between the magnetic cores. The resonant shield comprises an open ring-shaped structure, having two open ends which are connected by a capacitor to form a resonant circuit.