Cryopump Controller Cool-Down Mode
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Solution Overview
Problem
Cryopumps face challenges in shortening the cooling time, particularly when a large temperature difference is needed between the high and low temperature stages, leading to extended downtime during the cool-down process.
Innovation Solution
A cryopump system with a first and second stage cryopanel, utilizing a cryocooler with a first and second cooling stage, and a controller that selects a cool-down target temperature lower than the normal target temperature for the cool-down mode to expedite the cooling process, allowing the first stage cryopanel temperature to be controlled according to the selected target temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the cool-down target temperature is set to the normal target temperature (e.g., 80K), then the first stage cryopanel can be maintained at the appropriate temperature for normal operation, but the cooling time from room temperature is extended
Solution Approach 1:
The patent applies dynamics by making the target temperature adjustable based on operational requirements. The controller dynamically switches between cool-down mode (using lower target temperature of 60K) and normal operation mode (using normal target temperature of 80K), allowing the system to optimize for either speed or precision depending on the operational context.
Solution Approach 2:
The patent changes the temperature parameter during the cool-down process. By temporarily setting the target temperature to a lower value (60K) during cool-down and then switching to the normal target temperature (80K) for operation, the system achieves faster cooling while maintaining proper operational temperature.
2Productivity
If a large temperature difference is maintained between high and low temperature stages, then the cryopump can achieve better vacuum performance, but the cooling time is significantly extended
Solution Approach 1:
The patent applies preliminary action by pre-cooling the first stage cryopanel to a lower temperature (60K) before normal operation begins. This preliminary cooling creates a larger initial temperature difference that accelerates the cooling process, and the system then adjusts to the normal temperature difference (80K) once cooling is complete, ensuring both fast cool-down and good vacuum performance.
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 effectively shortens the cooling time of the cryopump by maintaining the first stage cryopanel at a lower temperature during the cool-down mode, enabling faster transition to the normal operating temperature, thus reducing downtime.
Implementation Method 1
a cryocooler with a first cooling stage and a second cooling stage
Implementation Method 2
cooling each of the first stage cryopanel and the second stage cryopanel from room temperature to the extremely low temperature region
Implementation Method 3
a first stage cryopanel...an extremely low temperature region
Implementation Method 4
a second stage cryopanel...an extremely low temperature region
Data Source
AI summary
A cryopump includes: a first-stage target temperature selection unit which includes a normal target temperature for a normal mode of maintaining each of a first stage cryopanel and a second stage cryopanel at an extremely low temperature region, and a cool-down target temperature lower than the normal target temperature, for a cool-down mode of cooling each of the first stage cryopanel and the second stage cryopanel from room temperature to the extremely low temperature region, and selects the normal target temperature as a first-stage target temperature in a case where a current operation mode is the normal mode, and at least temporarily selects the cool-down target temperature as the first-stage target temperature in a case where the current operation mode is the cool-down mode; and a first-stage temperature control unit which controls a first-stage cryopanel temperature according to the selected first-stage target temperature.