Cryogenic refrigerator
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Solution Overview
Problem
Cryocoolers with multiple compressors in parallel face backflow issues when one compressor stops, leading to adverse effects on components and reduced cooling performance, and the addition of backflow countermeasures like check valves increases manufacturing costs.
Innovation Solution
Incorporating state detection sensors and a compressor control unit to detect the state of each compressor and synchronously stop the other compressor main bodies when one is halted, preventing backflow without the need for additional countermeasures like check valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a check valve is added to prevent backflow, then backflow can be prevented or mitigated, but pressure loss in forward flow increases and cooling performance decreases
Solution Approach 1:
The system uses state detection sensors to monitor compressor operation status and feeds this information back to the control unit. When backflow is detected (via compressor stop signal), the control unit automatically stops other compressors to prevent backflow without requiring mechanical check valves, thus avoiding pressure loss while maintaining backflow prevention.
Solution Approach 2:
The patent replaces the mechanical check valve system with an electronic control system that uses sensors and a control unit to prevent backflow. This substitution eliminates the pressure loss associated with mechanical check valves while achieving the same backflow prevention function through automated compressor shutdown.
2Reliability
If a check valve is added to prevent backflow, then backflow can be prevented or mitigated, but manufacturing costs increase
Solution Approach 1:
The state detection sensors and control unit serve multiple functions: they monitor compressor operation status for normal control purposes and simultaneously detect compressor stops to prevent backflow. This multi-functionality eliminates the need for separate backflow prevention components, reducing manufacturing costs while maintaining reliability.
Solution Approach 2:
The control system automatically detects compressor stop conditions and initiates the shutdown of other compressors without requiring additional backflow prevention components. The system uses its existing sensors and control logic to self-manage backflow prevention, avoiding extra manufacturing costs.
3Productivity
If multiple compressors operate in parallel, then high flow rate can be supplied to cold head, but backflow occurs when one compressor stops
Solution Approach 1:
The control unit continuously receives feedback from state detection sensors about each compressor's operation status. When one compressor stops, this feedback triggers the control unit to immediately stop other compressors, preventing backflow while allowing multiple compressors to operate in parallel during normal conditions to maintain high cooling capacity.
Solution Approach 2:
The system dynamically adjusts the number of operating compressors based on real-time conditions. During normal operation, multiple compressors run in parallel to provide high cooling capacity. When a compressor stops, the system dynamically transitions to stopping all compressors to prevent backflow, allowing flexible adaptation to changing conditions.
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 solution effectively mitigates backflow while maintaining cooling performance and reducing manufacturing costs by using existing components for state detection, such as motor current sensors, to promptly stop operating compressors when one fails.
Implementation Method 1
a plurality of state detection sensors that are provided to correspond to the plurality of compressor main bodies respectively and each detect a state of a corresponding compressor main body to output a state detection signal
Implementation Method 2
The compressor compresses a working gas of the cryocooler to a high pressure and supplies the working gas to the expander
Implementation Method 3
The working gas is expanded by the expander to generate cold. The expansion decreases a pressure of the working gas
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A cryocooler 10 includes a cold head 14, a plurality of compressor main bodies 16 that are connected to the cold head 14 in parallel, a plurality of state detection sensors 20 that are provided to correspond to the plurality of compressor main bodies 16 respectively, the plurality of state detection sensors 20 each detecting a state of the corresponding compressor main body 16 to output a state detection signal S1, and a compressor control unit 40 that is configured to, in a case where a state detection signal S1 from any one state detection sensor 20 of the plurality of state detection sensors 20 indicates that the corresponding compressor main body 16 is stopped, stop also the other compressor main body 16.