Proximity Sensor Rotor Stator Clearance Dry Vacuum Pump
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Solution Overview
Problem
Existing dry vacuum pumps in semiconductor manufacturing face challenges in accurately predicting failures or deviations from optimal operation due to wear and tear, as traditional monitoring methods like vacuum pressure drops can be caused by various issues, making it difficult to determine when maintenance is needed.
Innovation Solution
A sensor system mounted on the stator of the pump, connected to a processing circuit, measures the absolute distance between the rotor and stator surfaces, storing and analyzing these values to detect deviations and potential failures, providing real-time feedback and warnings for optimal clearance maintenance and predictive maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional vacuum pressure monitoring is used to detect pump performance degradation, then the monitoring system is simple, but it cannot accurately predict failures or distinguish between different causes of vacuum drops
Solution Approach 1:
The patent replaces traditional mechanical/vacuum-based monitoring with electromagnetic sensing technology. A proximity sensor using electromagnetic fields measures the air gap between rotor and stator non-contactually, substituting the mechanical vacuum pressure monitoring system with an electromagnetic measurement system that provides precise failure prediction capability.
Solution Approach 2:
The patent introduces a proximity sensor as an intermediary measurement device between the rotor-stator system and the monitoring system. This sensor acts as a mediator that converts physical air gap changes into electrical signals, enabling accurate detection of wear and potential failures without directly interfering with the pump operation.
2Productivity
If rotor and stator clearances are maintained within tight tolerances through design and manufacturing, then pump efficiency is optimized, but wear and thermal expansion cause clearance drift over time
Solution Approach 1:
The patent implements a feedback mechanism where the proximity sensor continuously monitors the air gap between rotor and stator, and this information is fed back to the control system. The controller processes the sensor signals and can trigger warnings or adjustments to maintain optimal clearances, creating a closed-loop system that compensates for wear and thermal effects.
Solution Approach 2:
The patent monitors changes in the air gap parameter over time to detect wear trends and predict failures. By tracking the evolution of clearance dimensions and comparing them against predetermined thresholds, the system adapts its monitoring strategy based on the actual state of the pump components.
3Temperature
If a proximity sensor is mounted to detect rotor axial thermal expansion, then thermal effects are compensated, but the system cannot detect radial wear or other failure modes
Solution Approach 1:
The patent divides the monitoring function into multiple independent sensor positions around the rotor-stator interface. By placing proximity sensors at different locations (radially and axially), each sensor monitors a specific aspect of the air gap, and the combined data provides comprehensive coverage of various failure modes including wear, thermal expansion, and vibrations.
Solution Approach 2:
The patent extends monitoring from a single axial measurement point to multiple dimensions by positioning sensors both radially and axially around the rotor-stator interface. This multi-dimensional measurement approach enables detection of wear patterns, thermal distortion, and vibrations that would be invisible to a single-point sensor.
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 allows for accurate and consistent determination of rotor-to-stator clearance, optimizing pump performance over its service life and enabling timely maintenance decisions based on precise analysis of wear and vibration data.
Implementation Method 1
a sensor mounted to the stator and having an output connected to a processing circuit, said circuit being arranged to analyse the output of the sensor to determine the absolute distance between a point on the surface of the rotor and the sensor
Data Source
Figure 1~2
Figure 3~4
AI summary
A dry vacuum pump comprises a stator (10) which defines an internal chamber (11) in which a rotor (12) is rotationally mounted. A sensor (18) is mounted to the stator (10) and having an output (26) connected to a processing circuit (27) arranged to analyse the output of the sensor (18) to determine the absolute distance between a point on the surface of the rotor (12) and internal stator surface (10). The rotor to stator clearance can thus be accurately determined in real time during operation of the pump, so that the pump performance can be optimised over its serviceable life.