Magnetic-Preload Rotary Coupling for Error Motion Isolation
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Solution Overview
Problem
Conventional rotary couplings transmit unwanted error motions and heat directly from motors to rotary stages, affecting the precision and performance of sensitive components like diffraction gratings in optical systems.
Innovation Solution
A rotary coupling design featuring first and second coupling bodies with cylindrical elements and magnets, where the magnets provide a repulsive magnetic force to preload the cylindrical elements against each other at a single point of contact, isolating unwanted translations and rotations while allowing thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rigid binding is used between motor and rotary stage, then structural simplicity is improved, but error motions are directly transmitted to the rotary stage
Solution Approach 1:
The rigid direct connection between motor and rotary stage is segmented into multiple independent coupling bodies (first coupling body, second coupling body) connected through cylindrical elements. This segmentation allows each component to independently handle specific functions: the first cylindrical element transmits rotational motion while the second cylindrical element suppresses error motions, thereby resolving the contradiction between structural simplicity and precision.
Solution Approach 2:
Cylindrical elements serve as intermediary components between the motor and rotary stage. These intermediaries (first cylindrical element for motion transmission, second cylindrical element for error suppression) decouple the direct rigid connection, allowing the system to achieve both structural simplicity and high precision by mediating the interaction between motor and rotary stage.
2Ease of manufacture
If conventional rotary coupling is used, then ease of manufacture is improved, but heat is readily transferred from motor to rotary stage
Solution Approach 1:
The cylindrical elements act as thermal intermediaries with low thermal conductivity between the motor and rotary stage. This intermediary structure maintains the ease of manufacture of conventional couplings while significantly reducing heat transfer to the rotary stage and sensitive components, thereby resolving the contradiction between manufacturing simplicity and thermal isolation.
3Manufacturing precision
If magnetic preload is applied to preload cylindrical elements, then suppression of error motions is improved, but device complexity increases
Solution Approach 1:
Traditional mechanical preload mechanisms (such as springs or adjustment screws) are replaced with a magnetic preload system using permanent magnets. The magnetic field provides continuous preload force on the cylindrical elements without mechanical contact, achieving superior error motion suppression while reducing device complexity by eliminating mechanical preload components.
Solution Approach 2:
The magnetic preload system is self-regulating and requires no external adjustment or maintenance. The permanent magnets automatically maintain the optimal preload force on the cylindrical elements throughout operation, providing consistent error motion suppression without increasing device complexity or requiring additional control mechanisms.
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 design effectively transmits rotational motion while suppressing unwanted translations and rotations, maintaining precision and accommodating thermal distortion without degrading performance.
Implementation Method 1
The poles of the first and second magnets disposed at the gap have a same magnetic polarity such that a repulsive magnetic force is imparted on each of the first and second coupling bodies to thereby preload the first and second cylindrical elements against each other at a point of contact
Data Source
AI summary
Described is a rotary coupling that includes a pair of coupling bodies having parallel (preferably coincident) rotation axes, two cylindrical elements and a preload mechanism. A gap is provided between surfaces on the first and second coupling bodies. The first cylindrical element is disposed on the first coupling body and has a first cylinder axis, and the second cylindrical element is disposed on the second coupling body adjacent to the first cylindrical element and has a second cylinder axis that is perpendicular to the first cylinder axis. The preload mechanism imparts a force to each of the first and second coupling bodies and thereby preloads the first and second cylindrical elements against each other at a point of contact. One example of the preload mechanism includes a pair of magnets disposed opposite each other across the gap and another example of the preload mechanism includes an air bearing.