Vacuum Pump Deposited Material Sensor for Rotating Wall Thickness Detection
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Solution Overview
Problem
It is challenging to detect the thickness of deposited material in a vacuum pump's flow path before it causes operational disruption, especially when one wall surface is rotating or when using capacitance sensors, which also face difficulties in accurately measuring thickness based on pressure variations.
Innovation Solution
A vacuum pump design that includes a deposited material sensor arranged on the upstream or downstream side of a predetermined flow path position, where the sensor detects the presence or absence of deposited material, allowing for timely maintenance by changing its detection state from absent to present, enabling detection of the material's thickness just before it causes a disruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitance film thickness sensor is used to measure deposited material thickness, then maintenance can be executed before operation disruption occurs, but it is difficult to detect the thickness just before the cause of disruption occurs at rotating wall surfaces
Solution Approach 1:
The patent introduces a mediator substance (deposited material with different dielectric properties) between the capacitor electrode and the rotating wall surface. By measuring the capacitance change caused by this intermediate layer, the system can indirectly detect the thickness of deposited material on rotating surfaces without direct contact, solving the measurement difficulty while maintaining operational reliability
Solution Approach 2:
The patent replaces direct mechanical contact measurement methods with a non-contact capacitive sensing system. The capacitor electrode measures deposited material thickness through electrical field interaction rather than physical contact, enabling continuous monitoring of rotating surfaces without mechanical interference, thus improving both measurement capability and operational reliability
2Measurement precision
If electrodes are installed at two opposing positions on the wall surface to detect thickness vertically, then thickness measurement is possible, but it becomes difficult to install electrodes when one wall surface is rotating
Solution Approach 1:
The patent segments the measurement function into a stationary capacitor electrode and a rotating wall surface, allowing the sensing element to remain fixed while the object being measured rotates. This segmentation eliminates the need to install electrodes on rotating surfaces, simplifying manufacturing and installation while maintaining measurement precision through the capacitive field that spans the gap between stationary electrode and rotating surface
3Measurement precision
If spacing between electrode plates is widened to measure larger thickness with good sensitivity, then measurement sensitivity improves, but the size of the sensor increases making it difficult to arrange inside the flow path
Solution Approach 1:
The patent changes the measurement parameter from direct geometric spacing to electrical property (capacitance) measurement. By utilizing the relationship between capacitance and deposited material thickness through dielectric properties, the system achieves high measurement sensitivity without requiring large physical spacing between electrodes, thus maintaining compact sensor dimensions suitable for flow path installation
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 allows for the detection of deposited material thickness at a flow path position where a disruption is likely to occur, enabling maintenance to be performed before operational issues arise, thus reducing maintenance frequency and ensuring continuous pump operation.
Implementation Method 1
a thickness of such deposited material is measured by a capacitance film thickness sensor and, based on a sensor output value of the film thickness sensor
Data Source
AI summary
A deposited material sensor is arranged, in a flow path of a gas from an inlet port to an outlet port, on an upstream side or a downstream side of a predetermined flow path position where a cause of disruption to operation of the vacuum pump is to occur. In addition, the deposited material sensor detects a presence or absence of deposited material at the arrangement position of the deposited material sensor, and the arrangement position of the deposited material sensor is a position where a thickness of the deposited material at the predetermined flow path position assumes a predetermined thickness that corresponds to a maintenance time of maintenance for suppressing the cause when a detection state of the deposited material sensor changes from deposited material absent to deposited material present.