Butterfly Valve Vibration Detection for Stable Vacuum Pressure
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Solution Overview
Problem
Conventional butterfly valves in semiconductor manufacturing devices experience abnormal vibration due to mismatched control parameters and mechanical sliding resistance, leading to inefficient pressure control and potential breakage, which increases downtime and costs.
Innovation Solution
A butterfly valve with an integrated control unit and abnormal vibration detection program that analyzes the variation amount of the butterfly valve element's opening degree to distinguish between normal and abnormal vibrations, allowing for reliable detection without additional sensors, thus preventing unnecessary vibration and maintaining efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the servo motor gain is increased to accelerate reaction speed for faster pressure control, then the response speed of the servo motor increases, but the butterfly valve element becomes hard to stop and minute variation of the opening degree is unnecessarily repeated causing abnormal vibration
Solution Approach 1:
The control parameters of the servo motor are made dynamically adjustable based on operating conditions. The control unit switches between a first control parameter set (for fast response during pressure changes) and a second control parameter set (for stability during constant pressure), allowing the system to adapt its characteristics to current operational needs and avoid abnormal vibration while maintaining fast response when required
Solution Approach 2:
The invention changes the control parameters (gain, proportional band, integration time) of the servo motor based on the operating state of the vacuum chamber. When pressure is changing, parameters are optimized for fast response; when pressure is constant, parameters are adjusted to minimize vibration and ensure stable positioning, thus resolving the contradiction between speed and stability
2Reliability
If control parameters of the motor mismatch or mechanical sliding resistance increases due to assembling failure and aging degradation, then the motor may abnormally vibrate, but detecting this vibration requires additional sensors that increase cost
Solution Approach 1:
The control unit utilizes existing data from the pressure sensor and servo motor control system to detect abnormal vibration, rather than requiring separate vibration sensors. By monitoring the relationship between control commands and actual pressure changes, the system can identify abnormal conditions and self-diagnose problems, eliminating the need for additional detection components
Solution Approach 2:
The control unit is designed to perform multiple functions: it controls the servo motor to adjust the butterfly valve, monitors pressure changes in the vacuum chamber, and detects abnormal vibration conditions. This multi-functionality allows the system to use existing components for multiple purposes, avoiding the need for dedicated vibration sensors and reducing overall system complexity
Data Source
AI summary
A butterfly valve to be placed on a pipe between a vacuum chamber provided with a pressure sensor and a vacuum pump is configured to control the pressure in the vacuum chamber. The butterfly valve includes a servo motor, a butterfly valve element to be rotated about a rod connected to the servo motor in an opening or closing direction, and a control unit to adjust an opening degree of the butterfly valve element based on a pressure value of the vacuum chamber detected by the pressure sensor. The control unit is provided with an abnormal vibration detection program configured to whether or not abnormal vibration is occurring in the servo motor based on a variation amount of the opening degree of the butterfly valve element within a monitoring time while at least the pressure value of the vacuum chamber is stable.