GM cryocooler and method of operating GM cryocooler
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Solution Overview
Problem
There is a lack of practical multi-cylinder type Gifford-McMahon (GM) cryocoolers suitable for practical use, particularly in the gas-driven category, which are rare and complex due to the need for multiple valves and intricate flow paths.
Innovation Solution
A multi-cylinder GM cryocooler design featuring two cold heads with shared valve units and bypass flow paths, allowing for simplified and compact drive units by using four valves to operate both cold heads in synchronized phases, and enabling easy detachment of cold heads for maintenance without disrupting cooling operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple valves and intricate flow paths are used to operate multi-cylinder GM cryocoolers, then the cooling capacity is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple valve functions into shared valve units. Specifically, the first and second intake valves are integrated into a single shared valve unit, as are the first and second exhaust valves. This merging reduces the total number of valves from eight to four, thereby reducing device complexity while maintaining the multi-cylinder cooling capability
Solution Approach 2:
The shared valve units perform multiple functions simultaneously. The first shared valve unit controls gas flow to both the first drive chamber and the second cylinder, while the second shared valve unit controls gas flow to both the second drive chamber and the first cylinder. This multi-functionality allows fewer valves to manage the complex multi-cylinder system
2Ease of repair
If cold heads are made detachable for maintenance, then the ease of repair is improved, but the reliability of continuous cooling operation deteriorates
Solution Approach 1:
The cryocooler system is segmented into independent cold heads that can be detached separately. Each cold head (first and second) can be removed from its respective cold head housing without affecting the other cold head's operation, enabling independent maintenance while preserving system functionality
Solution Approach 2:
Bypass flow paths act as intermediary routes that allow cooling gas to flow around detached cold heads. When a cold head is removed for maintenance, the bypass flow paths enable the other cold head to continue operating by providing alternative gas flow routes, thus maintaining continuous cooling capability
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
The design simplifies the drive unit, reduces the number of valves, and allows for continuous cooling during maintenance by bypassing gas flow, enhancing operational efficiency and reducing maintenance time.
Implementation Method 1
a first drive piston that drives the first displacer in the axial direction, and a first drive chamber that houses the first drive piston
Implementation Method 2
a first displacer that is reciprocable in an axial direction, a first cylinder that houses the first displacer
Data Source
AI summary
A GM cryocooler includes a first cold head including a first displacer that is reciprocable in an axial direction, a first drive piston that drives the first displacer in the axial direction, and a first drive chamber that houses the first drive piston; a second cold head including a second displacer that is reciprocable in the axial direction, and a second cylinder that houses the second displacer; a first intake valve that is connected to both the first drive chamber and the second cylinder so as to supply working gas in parallel to the first drive chamber and the second cylinder; and a first exhaust valve that is connected to both the first drive chamber and the second cylinder so as to collect the working gas in parallel from the first drive chamber and the second cylinder.