Cryopump Regeneration Control via Reversible Motor
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Solution Overview
Problem
The existing cryopump regenerating method is inefficient as it cannot independently control the temperature of the first and second stage cooling stages, leading to a longer regeneration time and potential overheating of the first stage cooling stage before the second stage reaches the target temperature.
Innovation Solution
The cryopump incorporates a reversible motor with first and second stage temperature detection parts to control the rotation direction based on detected temperatures, allowing for secure temperature control of both stages and preventing excessive temperature rise, thereby shortening regeneration time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cryogenic cooler operates in reverse to raise temperature for regenerating, then the temperature of the cooling stages increases, but the first stage cooling stage overheats before the second stage reaches target temperature
Solution Approach 1:
The temperature control system is segmented into two independent control loops, one for each cooling stage. Each stage has its own temperature detection part and control parameters, allowing independent monitoring and control of first and second stage temperatures during the regenerating process
Solution Approach 2:
Different control strategies are applied to different stages based on their specific thermal characteristics. The first stage uses a lower target temperature (e.g., 150K) while the second stage uses a higher target temperature (e.g., 300K), matching their respective thermal capacities and regeneration requirements
2Loss of time
If the reversible motor rotates at high speed to quickly raise temperature, then regeneration time is reduced, but temperature control precision deteriorates
Solution Approach 1:
The reversible motor operates dynamically with variable rotational speed controlled by an AC power supply. The control system adjusts the motor speed based on real-time temperature feedback from detection parts, enabling both rapid temperature rise when needed and precise control when approaching target temperatures
Solution Approach 2:
Temperature detection parts continuously monitor the temperature of each cooling stage and feed this information back to the control system. The control system uses this feedback to adjust the reversible motor speed and AC power supply output, creating a closed-loop control system that achieves both speed and precision
3Device complexity
If the cooling cycle is reversed for regenerating, then special heating equipment is eliminated, but independent temperature control of each stage is lost
Solution Approach 1:
The cryogenic cooler is designed to perform multiple functions: normal cooling operation and regenerating heating operation. By reversing the cooling cycle, the same cryogenic cooler structure provides heating functionality, eliminating the need for separate heating equipment while maintaining temperature control capability through the multi-functional design
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 ensures that both stages are securely raised to target temperatures without frequent speed changes of the reversible motor, reducing regeneration time and preventing overheating, thus enhancing the reliability and efficiency of the cryopump.
Implementation Method 1
a method for raising the temperature, for example, a method discussed in Japanese Patent No. 2567369 is known. In the method discussed in Japanese Patent No. 2567369, a temperature rising cycle is realized by reversing a cooling cycle of the cryogenic cooler and the cryogenic cooler itself is used as a heat source.
Implementation Method 2
first and second stage temperature detection parts to control the rotation direction based on detected temperatures
Implementation Method 3
first and second stage cooling stages being cooled by rotation in the forward direction of the reversible motor
Implementation Method 4
being heated by rotation in the reverse direction of the reversible motor
Data Source
AI summary
A cryopump and a regenerating method of the cryopump whereby temperatures of a first stage and a second stage can be securely increased to target temperatures and time required for regenerating can be shortened are provided. At the time of regenerating, the temperature of the second stage cooling stage is controlled based on the temperature detected by the second temperature detection part. In the case where the temperature of the first stage cooling stage reaches the limiting temperature, namely critical temperature, of the first stage displacer, the rotation in the reverse direction of the reversible motor is controlled or stopped and thereby the regenerating process is stopped for a while.