Vacuum Pump Contact Cause Estimation Using Displacement Thresholds
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Solution Overview
Problem
Existing vacuum pump technologies, such as turbomolecular pumps, face challenges in accurately distinguishing between contact caused by physical contact between the rotating body and stator due to unbalance, external impacts, or product accumulation, leading to potential defects and maintenance timing issues.
Innovation Solution
A vacuum pump system that includes displacement and physical quantity detection means, with set thresholds, allows for the estimation of contact causes without the need for vibration sensors, using stored displacement and physical quantity signals to determine the timing and nature of contact, enabling proper maintenance actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vibration sensors such as acceleration pickup are used to detect contact between rotating body and stator, then contact detection accuracy is improved, but device complexity and cost increase due to need for band-pass filter and elastic member fixing method
Solution Approach 1:
The invention extracts the contact detection function from the vibration sensor system and implements it using the displacement sensor that is already present in the turbomolecular pump. By utilizing the displacement sensor's output to detect contact through threshold comparison, the patent eliminates the need for additional vibration sensors, band-pass filters, and elastic member fixing methods, thereby reducing device complexity while maintaining contact detection capability
Solution Approach 2:
The displacement sensor, originally designed for monitoring rotating body position, is made multi-functional by also enabling contact detection between the rotating body and stator. The control unit analyzes the displacement sensor output to determine contact occurrence, allowing a single sensor to serve both position monitoring and contact detection functions, thus avoiding additional hardware requirements
2Duration of action of moving object
If maintenance timing is predicted using conventional techniques, then maintenance scheduling is established, but inability to discriminate between different causes of vibration amplitude increase leads to inaccurate maintenance timing
Solution Approach 1:
Instead of using vibration sensors to detect contact and then inferring causes, the invention inverts the approach by using the displacement sensor output directly to detect contact and determine its causes. By analyzing whether the displacement sensor signal exceeds predetermined thresholds during rotation, the system can distinguish between contact caused by product accumulation versus other causes, enabling accurate maintenance timing prediction
Solution Approach 2:
The control unit continuously monitors the displacement sensor output and provides feedback by comparing it against predetermined thresholds. When the displacement exceeds the threshold, the system identifies contact occurrence and determines its cause, enabling real-time adjustment of maintenance scheduling based on actual contact conditions rather than fixed time intervals
Data Source
AI summary
Provided are a vacuum pump and a method for the vacuum pump in which, when contact between a rotating body and a stator is sensed, the cause of the contact can be analyzed. Contact determination is made using a threshold for rotating body contact determination for a displacement signal and a threshold for rotating body contact determination for an acceleration signal. The amount of unbalance of a rotating body is determined using a threshold for amount-of-unbalance increase determination for the displacement signal and a threshold for amount-of-unbalance increase determination for the acceleration signal. When, in one of the displacement signal and the acceleration signal, the threshold for amount-of-unbalance increase determination or the threshold for amount-of-unbalance increase determination is exceeded within a predetermined time before determination of an estimated time point of contact, the contact is determined not to be caused by an increase in accumulation of products.