Compressor unit of a split stirling cryogenic refrigeration device
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Solution Overview
Problem
Existing cryogenic refrigeration devices, particularly Stirling cycle-based systems, face challenges in minimizing size and power consumption while reducing disruptive vibrations, especially when used in applications like infrared detectors, where they need to fit within constrained spaces and operate with limited power sources.
Innovation Solution
A split Stirling cryogenic refrigeration device with a compressor unit utilizing a linear electromagnetic actuator driven by a stator assembly with a driving coil and movable permanent magnets, allowing for efficient compression and decompression of a gaseous working agent, and a flexible transfer line connecting the compressor and expander units to manage vibrations and heat transfer effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional compressor is used in a cryogenic refrigeration device, then the compression function is achieved, but the device size becomes large and vibrations increase
Solution Approach 1:
The compressor is divided into separate functional modules: a vibration isolation platform for the compression chamber, a flexible transfer line connecting to the expansion chamber, and a separately mounted displacer. This segmentation isolates vibration sources from sensitive components while maintaining functional integration.
Solution Approach 2:
A flexible transfer line acts as an intermediary element between the compression chamber and expansion chamber, transmitting the gaseous working agent while mechanically decoupling the two chambers to prevent vibration transmission. The flexible nature of this intermediary absorbs and isolates vibrational energy.
2Volume of moving object
If the compressor size is reduced to fit in constrained spaces, then the device becomes more compact, but power consumption increases
Solution Approach 1:
The conventional mechanical drive system (crankshaft, connecting rods, valves) is replaced with a magnetically coupled piston system. Magnetic fields transmit force across a clearance gap without mechanical contact, eliminating the need for complex mechanical transmission components and reducing overall compressor size while improving efficiency.
Solution Approach 2:
The system operates by changing the magnetic field parameters (strength, frequency, phase) to control piston motion and gas compression. By adjusting magnetic field characteristics rather than mechanical dimensions, the system achieves compact size while maintaining efficient power utilization.
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 configuration enables efficient cooling of objects to cryogenic temperatures with reduced size and power consumption, minimizing vibrations and heat transfer disruptions, making it suitable for compact applications like infrared detectors.
Implementation Method 1
a linear electromagnetic actuator that is configured to drive the piston, the actuator including: a stator assembly that includes a driving coil that is wound about the longitudinal axis and that is enclosed within a toroidal back iron
Implementation Method 2
two movable permanent magnets that are located radially exteriorly to the stator assembly, the two movable permanent magnets being magnetically polarized parallel to the longitudinal axis and oppositely to one another such that an alternating electrical current that flows through the driving coil causes the movable assembly to move back and forth
Data Source
Figure 1~2
Figure 3
AI summary
A compressor unit (12) of a cryogenic refrigeration device includes a compression chamber (18) that is connectable via a transfer line to an expander unit. A piston (28) is configured to alternately compress and decompress a gaseous working agent in the compression chamber. An electromagnetic actuator (20) includes a stator assembly (24) with a driving coil (30) that is wound about the longitudinal axis and that is enclosed within a toroidal back iron (32) except for a coaxial cylindrical gap (34) in a radially outward facing surface. A movable assembly (26) connected to the piston includes two movable permanent magnets (40,42) separated by a ferromagnetic spacer (44) radially exterior to the stator assembly. The movable magnets are magnetized parallel to the longitudinal axis and opposite to one another such that an alternating electrical current in the driving coil causes the movable assembly to parallel to the longitudinal axis to periodically drive the piston into and out of the compression chamber.