Compact Direct-Drive Spindle With Stacked Sealed Motor Modules
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Solution Overview
Problem
Current vacuum robots face challenges in isolating motors and encoders from the vacuum environment effectively, particularly in spindle drives, where existing solutions like ferrofluidic or lip seals are inefficient, and the Brooks MAGNATRAN products place magnet rotors and encoders directly in the vacuum, leading to design limitations.
Innovation Solution
The implementation of an inverted drive design where stators are placed on a stationary inner post and the rotor is positioned outside, with shaftless motor configurations that include stacked drive motors with stators on a fixed post and rotors surrounding them, allowing for compact and efficient torque transmission while maintaining environmental isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferrofluidic or lip seals are used to isolate motors from vacuum, then environmental isolation is improved, but device complexity and reliability deteriorate due to seal inefficiency
Solution Approach 1:
The patent extracts the motor entirely from the vacuum environment by placing it in the atmospheric side, eliminating the need for any seals between the motor and vacuum chamber. The motor shaft extends through the vacuum chamber wall to directly drive the spindle, removing ferrofluidic or lip seals from the system and achieving reliable environmental isolation without complex sealing mechanisms.
Solution Approach 2:
The patent introduces a magnetic coupling mechanism as an intermediary between the atmospheric motor and the vacuum-side spindle. Magnetic fields penetrate the vacuum chamber wall to transmit rotational force without physical contact, serving as a mediator that transfers torque while maintaining vacuum integrity without requiring mechanical seals.
2Device complexity
If magnet rotors and encoders are placed directly in vacuum environment, then device complexity is reduced, but manufacturing precision and reliability deteriorate
Solution Approach 1:
The patent extracts both the magnet rotor and encoder from the vacuum environment by housing them within the atmospheric motor assembly. This placement protects sensitive encoder components from vacuum conditions that could affect manufacturing precision, while still enabling vacuum-compatible operation through the magnetic coupling mechanism.
3Volume of moving object
If shaftless motor configurations are used, then compactness is improved, but torque transmission efficiency worsens
Solution Approach 1:
The patent uses magnetic fields as an intermediary to transmit torque from the atmospheric motor to the vacuum-side spindle without mechanical shafts. This magnetic coupling mechanism achieves compact shaftless configuration while maintaining efficient torque transmission through direct magnetic interaction across the vacuum chamber wall, avoiding energy losses associated with mechanical seal interfaces.
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 enhances the compactness and torque efficiency of vacuum robot drives, improves environmental isolation, and allows for more flexible and effective operation within vacuum environments by decoupling the stator and rotor positions, addressing the inefficiencies of previous designs.
Implementation Method 1
a rotor surrounded by a stator, where the rotor is configured to rotate about a central axis. The rotor includes a plurality of magnets arranged in a circular pattern around the central axis. The stator includes a plurality of coils arranged in a circular pattern around the central axis
Implementation Method 2
The rotor includes a plurality of magnets arranged in a circular pattern around the central axis. The stator includes a plurality of coils arranged in a circular pattern around the central axis
Data Source
AI summary
A sealed actuator including stacked motor modules. Each motor module has a motor module housing, a motor stator attached to a respective motor module housing, a motor rotor in communication with a respective motor stator, and a stator seal disposed between the motor stator and motor rotor, surrounding the motor rotor and having a sealing surface interface, that interfaces with a respective sealing housing surface of the motor module housing, facing the motor rotor to seal the motor stator from the motor rotor. The motor module housings are stacked against each other and the sealing housing surface interfaced, at the sealing surface interface facing the rotors, to the respective stacked stator seals of the motor module housings forms a substantially continuous seal interface of the stacked motor modules sealed by the stacked stator seals to form a continuous barrier seal between the motor rotors and the motor stators.