Cryopump Regeneration Valve Timing Control
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Solution Overview
Problem
The regeneration process of cryopumps is influenced by differences in pressure between multiple cryopumps, which complicates parallel regeneration and increases overall regeneration time.
Innovation Solution
A cryopump system with a common roughing pump and controller that manages the opening and closing of rough valves to introduce a delay between switching between cryopumps, allowing for synchronized regeneration by setting a delay time between closing one rough valve and opening another, thereby managing pressure differences and optimizing the regeneration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple cryopumps are regenerated in parallel using a common roughing pump, then regeneration time is reduced, but pressure differences between cryopumps complicate the process and increase overall regeneration time
Solution Approach 1:
The system performs preliminary actions by pre-cooling the roughing pump and preparing the rough valves before initiating the regeneration process. The controller pre-configures the timing sequence for valve operations, ensuring that all components are ready before parallel regeneration begins, thus simplifying the control process while maintaining high speed.
Solution Approach 2:
The controller implements periodic action by using timed cycles for opening and closing rough valves in a sequential pattern. Each valve operates in a predetermined time sequence, creating a rhythmic control pattern that simplifies the management of pressure differences while maintaining parallel regeneration efficiency.
2Loss of time
If rough valves are switched quickly between cryopumps, then regeneration time is reduced, but pressure differences cause disruptions and increase regeneration time
Solution Approach 1:
The controller performs preliminary timing calculations to determine the optimal delay period before switching rough valves between cryopumps. This preliminary action ensures that pressure equalization occurs before the next valve switches, preventing disruptions while minimizing total regeneration time.
Solution Approach 2:
The system incorporates a delay time as a cushioning mechanism between valve switching events. This time buffer allows pressure to equalize across the roughing pump, preventing sudden pressure shocks that would disrupt the regeneration process, while keeping the buffer as short as possible to maintain efficiency.
3Reliability
If a delay time is introduced between valve switching operations, then pressure differences are minimized, but regeneration time increases
Solution Approach 1:
The controller dynamically adjusts the delay time between valve switching operations based on real-time pressure measurements and the specific characteristics of each cryopump. This dynamic optimization ensures that each delay is precisely calibrated to equalize pressure without unnecessary waiting, achieving reliable pressure control while minimizing total regeneration time.
Solution Approach 2:
The system changes the timing parameter (delay time) between valve operations to optimize the balance between pressure control and regeneration speed. By adjusting this critical parameter based on system conditions, the controller achieves reliable pressure equalization while keeping the delay as short as possible to maintain high productivity.
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 reduces the overall regeneration time of multiple cryopumps by synchronizing the regeneration process and minimizing pressure-related disruptions, ensuring efficient operation in vacuum environments like semiconductor manufacturing.
Implementation Method 1
first rough-pumping a cryopump through the rough line; and second rough-pumping another cryopump through the rough line
Data Source
AI summary
A cryopump system includes: a plurality of cryopumps connected to a common roughing pump in a rough line and provided with a plurality of rough valves in the rough line, respectively; and a controller configured to control each of the rough valves for regenerating a corresponding one of the plurality of cryopumps. A delay time is set between closing of an open one of the plurality of rough valves and opening of a closed one of the plurality of rough valves. The controller applies the delay time uniformly upon closing of each of the rough valves.