Booster Pump Speed Control for Vacuum Chamber Noise Reduction
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Solution Overview
Problem
Vacuum pumping systems in industrial applications, such as semiconductor and solar manufacturing, experience high noise levels due to rapid deceleration of booster pumps when exposed to sudden increases in inlet pressure during the evacuation of loadlock chambers, which can lead to increased noise and operational inefficiencies.
Innovation Solution
Implementing a method to reduce the speed of the booster pump before it is exposed to high gas loads, allowing it to decelerate more gradually and then accelerate back to rated speed when the high gas load is established, using a variable speed motor and control unit to manage the rotor speed based on pressure changes and sensor inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the booster pump operates at rated speed during normal evacuation, then the evacuation efficiency is maximized, but the noise level increases significantly when exposed to sudden high gas loads
Solution Approach 1:
The booster pump's rotational speed is made dynamically adjustable rather than fixed at rated speed. The control system continuously monitors inlet pressure and adjusts the motor speed accordingly - maintaining rated speed during normal evacuation for maximum efficiency, and reducing speed when high gas loads are detected to minimize noise. This dynamic adaptation resolves the contradiction between productivity and noise control.
Solution Approach 2:
The operating parameters of the booster pump, specifically the rotational speed, are changed based on operating conditions. By varying the speed parameter in response to inlet pressure changes, the system optimizes performance across different operating states - high speed for evacuation efficiency and low speed for noise reduction during high gas load conditions.
2Object-affected harmful factors
If the booster pump speed is reduced to minimize noise, then the noise level decreases, but the evacuation rate and productivity are reduced
Solution Approach 1:
The booster pump operates in periodic cycles, alternating between high-speed evacuation mode and low-speed noise-reduction mode. The control system detects periodic patterns in gas load and adjusts speed accordingly, maintaining high productivity during evacuation phases while minimizing noise during high gas load phases, thus resolving the contradiction between noise control and evacuation rate.
3Speed
If the booster pump rapidly decelerates in response to high gas load, then the response time is minimized, but the mechanical stress and operational wear increase
Solution Approach 1:
The control system anticipates high gas load conditions by monitoring inlet pressure and proactively reduces booster pump speed before the full impact of the gas load occurs. This cushioning approach prevents rapid deceleration and associated mechanical stress, thereby protecting the pump's mechanical components while still maintaining rapid response to changing conditions.
Solution Approach 2:
The control system takes preliminary action by detecting pressure changes and adjusting the booster pump speed in advance of the actual high gas load condition. This preliminary speed adjustment prevents the need for rapid deceleration, reducing mechanical stress on the pump components while maintaining effective response to operating conditions.
Data Source
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AI summary
A method and apparatus for reducing undesirable noise generated by a vacuum pumping system is disclosed. The vacuum system operates to reduce the pressure in chamber to a first pressure value. The system then detects that the pressure at the vacuum pump systems inlet is about to change to a second higher pressure and, in response, the speed of a booster pump in the vacuum pump system is reduced below the rated speed for the pump. When the pressure at the vacuum pumps inlet is above second pressure, the speed of the booster pump is increased to the rated speed. Thus, the booster pump is slowed down prior the pump system becoming exposed to a rapid increase in inlet pressure. This has been found to reduce noise levels to a more acceptable level.