Vacuum Pump Sensor Detecting Deposit Thickness via Capacitance Rate
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vacuum pumps face challenges in accurately detecting the accumulation of deposits to a prescribed thickness in the flow path, especially when the chemical composition of the deposits is unknown, leading to potential damage from blockages between the rotating and stator portions.
Innovation Solution
A vacuum pump design featuring a main sensor with a pair of electrodes spaced one to two times the interval between the rotating and stator portions, equipped with a capacitance detection circuit, which detects the accumulation by monitoring the change in capacitance increase rate, allowing for precise detection of deposit thickness regardless of chemical composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitance type film thickness sensor is used to detect deposit thickness, then the sensor can measure film thickness based on capacitance changes, but the measurement accuracy deteriorates when the chemical composition of the deposit is unknown or variable
Solution Approach 1:
The patent changes the detection parameter from absolute capacitance value to capacitance increase rate (rate of change). By monitoring how the capacitance changes over time rather than its absolute value, the system can detect when the deposit reaches a predetermined thickness regardless of the deposit's chemical composition or relative permittivity characteristics.
Solution Approach 2:
The patent creates a universal detection method that works across different chemical compositions. By using the capacitance increase rate rather than absolute capacitance values, the same sensor system can accurately detect deposit thickness for various materials without requiring composition-specific calibration or identification.
2Measurement precision
If the electrode interval is made smaller to improve detection sensitivity, then the detection precision improves, but the risk of damage from deposit collision increases
Solution Approach 1:
The patent performs preliminary detection by monitoring the capacitance increase rate before the deposit reaches critical thickness. The system detects when the deposit is approaching the electrode interval and triggers maintenance or cleaning operations in advance, preventing the deposit from accumulating to a level that would cause mechanical damage to the rotating portion.
Solution Approach 2:
The patent implements continuous monitoring of the capacitance increase rate to provide real-time feedback on deposit accumulation. This feedback mechanism allows the system to track deposit growth dynamically and take corrective action before the deposit reaches a dangerous thickness, balancing detection sensitivity with equipment protection.
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 enables reliable detection of deposit accumulation before it blocks the space between the rotating and stator portions, preventing damage and ensuring smooth operation by accurately estimating the deposit thickness based on capacitance changes.
Implementation Method 1
a capacitance detection circuit which is connected to the pair of electrodes and which detects a capacitance between the pair of electrodes
Implementation Method 2
the reactive substance and the like are deposited on a wall surface of the flow path
Implementation Method 3
the capacitance between the electrodes varies in accordance with a relative permittivity of the deposit
Data Source
Figure 1
Figure 2
Figure 3
AI summary
To provide a vacuum pump which includes a sensor capable of detecting that, even when a chemical composition of a deposit inside a flow path cannot be specified, the deposit has accumulated to a prescribed thickness in the flow path. A vacuum pump 1 includes: a rotating portion and a stator portion between which an internal flow path is formed; an exhaust mechanism which sends gas from a suction port toward an outlet port through the internal flow path; and a main sensor 42 for detecting that a deposited material has reached a prescribed thickness at a detection object position of the internal flow path, wherein the main sensor 42 includes at least a pair of electrodes 54 and 56 disposed in the internal flow path at an interval corresponding to the prescribed thickness, and a capacitance detection circuit 46 which is connected to the pair of electrodes 54 and 56 and which detects a capacitance between the pair of electrodes 54 and 56, and the capacitance detection circuit 46 detects that a deposited material in the internal flow path has reached the prescribed thickness on the basis of a drop in an increase rate of the capacitance.