Vacuum Pump Speed Control for Noise Reduction
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Solution Overview
Problem
Vacuum pump systems used for evacuating lock chambers face a conflict between achieving short pump-out times and minimizing mechanical and thermal stress while maintaining low noise emission, as high rotational speeds required for quick evacuation lead to increased noise levels.
Innovation Solution
The system employs a controller to regulate the rotational speed of vacuum pumps by determining and evaluating cyclically occurring operating parameters such as motor current, inlet pressure, and temperature, reducing the rotational speed of vacuum pumps during valve opening to achieve noise reduction without compromising pump-out performance, and utilizes an energy storage or feedback unit to efficiently reuse braking energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high rotational speeds are used for quick evacuation, then pump-out time is reduced, but noise level increases
Solution Approach 1:
The controller reduces the rotational speed of the vacuum pump before the valve device is opened, based on predicted or detected valve opening events. This preliminary speed reduction prevents the noise surge that would occur during valve opening while maintaining quick pump-out capability after the valve opens.
Solution Approach 2:
The system dynamically adjusts the rotational speed of the vacuum pump based on operational conditions, specifically reducing speed during valve opening events and increasing it during active pumping phases. This dynamic control allows the system to optimize between noise reduction and pump-out performance in different operational states.
2Productivity
If high rotational speeds are maintained continuously, then pump-out performance is maximized, but mechanical and thermal stress increase
Solution Approach 1:
The controller reduces rotational speed in advance of valve opening events, which are periods of high mechanical stress. This preliminary action allows the pump to operate at lower speeds during stressful transitions, reducing mechanical and thermal stress while maintaining overall pump-out effectiveness through higher speeds during active pumping phases.
Solution Approach 2:
The system employs periodic cycles of high and low rotational speeds, matching the operational rhythm of valve openings and closings. During active pumping, high speeds maximize productivity; during valve transitions, reduced speeds minimize stress. This periodic modulation optimizes both performance and component longevity.
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 approach results in significant noise reduction, with rotational speed reductions of up to 80% during valve opening, while maintaining rapid pressure reduction in the lock chamber, and enhances energy efficiency by storing and reusing braking energy, thus addressing the noise and efficiency challenges of existing systems.
Implementation Method 1
A particularly suitable operating parameter is the motor current received by the electric motor driving the at least one vacuum pump
Implementation Method 2
utilizes an energy storage or feedback unit to efficiently reuse braking energy
Data Source
AI summary
A processing chamber is connected to a lock chamber. For evacuating the lock chamber and/or the processing chamber a vacuum pump system is provided. The latter comprises a vacuum pump equipment having at least one vacuum pump. Further, the vacuum pump system comprises a valve device for connection to the lock chamber as well as a controller. For noise reduction, a cyclically occurring operating parameter is determined by means of the controller. From said parameter it is determined at which point in time the valve is opened such that temporally before the opening of the valve the rotational speed of at least one of the vacuum pumps can be reduced. This results in a considerable noise reduction at continuing good pump-out times.