Concentric Actuator Cryocooler Design for Vibration Reduction
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Solution Overview
Problem
Cryocoolers face challenges in compactly packaging and reducing the mass of dynamically balanced moving mechanisms, leading to increased exported forces and torques, particularly in pulse tube and Stirling coolers, which affects their size and efficiency.
Innovation Solution
The implementation of concentric moving mechanisms using electromagnetic actuators with voice coils and magnetic circuits, where a balance actuator reduces vibrations caused by the compressor piston, allowing for a compact and lightweight design by positioning the balancer mechanism concentrically with the compressor and displacer mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple independent moving mechanisms (compressor, displacer, balancer) are used to achieve dynamic balance and reduce vibrations, then vibration reduction is improved, but device complexity and mass increase
Solution Approach 1:
The patent combines the compressor and balancer mechanisms into a single integrated actuator assembly. The compressor piston and balancer piston share common components including the magnetic circuit, voice coil assembly, and housing structure. This merging eliminates the need for separate independent mechanisms while maintaining the dynamic balance function, thereby reducing device complexity and mass while still achieving vibration reduction.
2Volume of moving object
If multiple independent moving mechanisms are packaged compactly, then device size is reduced, but mass of the mechanisms remains high
Solution Approach 1:
The patent implements a nested configuration where the balancer piston is positioned concentrically within the compressor piston assembly. The balancer mechanism is nested inside the compressor actuator housing, with both pistons sharing the same cylindrical space. This nesting arrangement achieves compact packaging that reduces device volume while the shared structural components reduce overall mass compared to separate mechanisms.
Solution Approach 2:
By merging the compressor and balancer into a single actuator assembly with shared magnetic circuits, voice coils, and housing, the patent reduces the total mass of moving mechanisms. The integrated design eliminates redundant structural elements that would exist in separate mechanisms, achieving weight reduction while maintaining compact form factor.
3Weight of moving object
If an inline cooler architecture with fewer mechanisms is used, then device size and mass are reduced, but exported forces and torques increase
Solution Approach 1:
The patent employs the balancer piston as a counterweight mechanism that generates opposing forces to cancel the exported forces and torques from the compressor piston. The balancer is driven by a voice coil that produces forces equal and opposite to the compressor reactions, actively compensating for the increased EFT that would otherwise result from the simplified inline architecture. This allows mass reduction while maintaining low exported forces.
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 results in a more compact and lighter cryocooler design that effectively minimizes exported forces and torques, enhancing the efficiency and performance of cryocoolers by actively balancing the compressor piston's vibrations.
Implementation Method 1
The first actuator includes at least one first voice coil and at least one first magnetic circuit, the at least one first voice coil of the first actuator configured to drive a compressor piston
Implementation Method 2
The second actuator includes at least one second voice coil and at least one second magnetic circuit, the at least one second voice coil of the second actuator configured to reduce the vibrations to the housing
Data Source
AI summary
A cryogenic cooler includes a housing, and first, second, and third actuators. The first actuator includes at least one first voice coil and at least one first magnetic circuit, the at least one first voice coil of the first actuator configured to drive a compressor piston, the first actuator causing vibrations to the housing when driving the compressor piston. The second actuator includes at least one second voice coil and at least one second magnetic circuit, the at least one second voice coil of the second actuator configured to reduce the vibrations to the housing caused by driving the compressor piston. The third actuator includes at least one third voice coil and at least one third magnetic circuit, the third actuator configured to drive a displacer piston. The compressor piston, balance mechanism, and displacer piston are concentrically formed within the cryogenic cooler.