Magnetic Rotor Position Feedback Across a Seal Partition
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Solution Overview
Problem
Existing position feedback systems for sealed robotic drives face challenges in ultra-high vacuum and aggressive environments, where electronic components within the sealed environment can corrode and optical sensors are prone to contamination and signal degradation due to exposure, leading to potential leaks and sensor failures.
Innovation Solution
A position feedback system that uses a magnetic sensor with a ferromagnetic flux loop and sensor air gap, where the sensor electronics are located outside the sealed environment, allowing for non-intrusive measurement of the motor rotor's position within the sealed environment without exposing electronic components to harsh conditions, using a seal partition to isolate the environments and prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic components are located within the sealed environment for position feedback, then position sensing can be achieved, but the electronic components are exposed to corrosion and contamination leading to sensor failure
Solution Approach 1:
The patent extracts the electronic components of the optical encoder from the sealed environment and places them in the unsealed environment. The only component remaining in the sealed environment is the optical scale attached to the rotor, which is passive and resistant to corrosion. This resolves the contradiction by enabling position sensing through the isolation wall while protecting all vulnerable electronic components from harsh conditions.
Solution Approach 2:
The patent introduces an optical isolation wall as an intermediary that allows optical signals to pass through while separating the sealed and unsealed environments. The optical scale in the sealed environment modulates light, and the sensors in the unsealed environment detect these modulated signals, enabling position feedback without direct exposure of electronics to the harsh environment.
2Ease of operation
If hermetically sealed connectors are used to route wires through the isolation wall, then electronic components can be connected, but leak sources are introduced compromising the sealed environment
Solution Approach 1:
The patent replaces the mechanical wire routing system with hermetically sealed connectors with an optical signal transmission system. Instead of passing electrical wires through the isolation wall, the system uses optical signals that pass through the isolation wall without requiring physical penetrations, thereby maintaining the integrity of the sealed environment while enabling electronic component connectivity.
3Measurement precision
If optical sensors are exposed to the sealed environment for position feedback, then position measurement can be performed, but contaminants are deposited on the feedback track leading to signal degradation
Solution Approach 1:
The patent extracts the optical sensors from the sealed environment and places them in the unsealed environment. Only the passive optical scale remains in the sealed environment, which is resistant to contaminant deposition. This eliminates the problem of contaminants being deposited on the feedback track while maintaining position measurement capability through optical signal transmission across the isolation wall.
4Measurement precision
If windows are provided through the isolation wall for sensor operation, then optical sensing can occur, but additional leak sources are created
Solution Approach 1:
The patent replaces the mechanical window penetration system with an optical transmission system through the isolation wall. The isolation wall is designed to be optically transparent, allowing light to pass through without requiring physical openings or windows. This maintains the integrity of the sealed environment while enabling optical sensing capability.
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 solution enables reliable and accurate position feedback in harsh environments without the need for hermetically sealed connectors, reducing the risk of leaks and contamination, and maintaining sensor integrity by keeping electronic components outside the sealed environment.
Implementation Method 1
a magnetic sensor with a ferromagnetic flux loop and sensor air gap
Implementation Method 2
a magnetic sensor with a ferromagnetic flux loop
Implementation Method 3
using a seal partition to isolate the environments and prevent contamination
Data Source
AI summary
A transport apparatus comprising a housing, a variable reluctance drive mounted to the housing, and at least one transport arm connected to the variable reluctance drive where the drive includes at least one rotor having salient poles of magnetic permeable material and disposed in an isolated environment, at least one stator having salient pole structures each defining a salient pole with corresponding coil units coiled around the respective salient pole structure and disposed outside the isolated environment where the at least one salient pole of the at least one stator and the at least one salient pole of the rotor form a closed magnetic flux circuit between the at least one rotor and the at least one stator, at least one seal partition configured to isolate the isolated environment; and at least one sensor including a magnetic sensor member connected to the housing, at least one sensor track connected to the at least one rotor, where the at least one seal partition is disposed between and separates the magnetic sensor member and the at least one sensor track so that the at least one sensor track is disposed in the isolated environment and the magnetic sensor member is disposed outside the isolated environment.