Concentric Cryocooler Flexure Suspension for Compact Sag Resistance
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Solution Overview
Problem
Cryogenic coolers face inefficiencies in packaging and mass due to the need for significant spacing between flexure stacks to prevent sag of cantilevered masses, which increases the overall size and volume of the system.
Innovation Solution
The system splits two independent flexure systems across a single magnetic structure, using concentrically oriented flexure connecting shafts and connectors to reduce the space between flexure stacks, allowing the motor's magnetic circuit to occupy the unused space and maintain mechanical advantage against sag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If flexure stacks are spaced apart to prevent sag of cantilevered masses, then radial stiffness is sufficient, but package volume and length increase significantly
Solution Approach 1:
The patent places the first and second flexure stacks concentrically, with the first flexure stack positioned inside the second flexure stack. This nesting arrangement allows both flexure stacks to be closely spaced while maintaining sufficient radial stiffness to prevent sag of the cantilevered compressor and expander masses, thereby reducing the overall package volume compared to traditional spaced arrangements.
Solution Approach 2:
The patent transitions from a linear spacing arrangement to a concentric/circular arrangement of flexure stacks. By positioning the flexure stacks in different radial dimensions rather than linearly along a single axis, the system achieves the necessary mechanical advantage against sag while minimizing the longitudinal length and overall package volume of the cryocooler.
2Stability of the object's composition
If flexure stacks are spaced apart to provide mechanical advantage, then cantilevered masses are supported, but device complexity and packaging efficiency worsen
Solution Approach 1:
The patent combines the suspension functions of multiple flexure stacks into a unified concentric arrangement around a single magnetic structure. This merging of suspension functions reduces the number of separate suspension subassemblies needed and simplifies the overall device complexity while maintaining alignment stability for the compressor and expander pistons.
Solution Approach 2:
The concentric flexure stack arrangement serves multiple functions simultaneously: it provides radial stiffness to prevent sag, maintains alignment stability for multiple moving masses, and enables compact packaging around the magnetic structure. This multi-functionality reduces the need for separate dedicated components, thereby reducing device complexity.
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 reduces the package size while maintaining resistance to cantilevered mass sag, offering simpler and more stable alignment procedures compared to traditional designs.
Implementation Method 1
a first mechanism coupled to the element at a first end thereof for maintaining alignment of the element; a second mechanism for maintaining alignment of the element
Implementation Method 2
a single magnetic structure to drive both the compressor and Stirling displacer pistons
Data Source
AI summary
A cryocooler in which two independently moving flexure systems are split across a single magnetic structure, decreasing package size and increasing resistance to cantilevered mass sag due to external forces. A series of concentrically oriented flexure coupling shafts are provided that allow two independently moving flexure assemblies to be split across a single motor. A series of connectors are included on the forward side of the motor that pass through the outer shaft and allow the inner connecting shaft to be mounted to its flexures without interference. A series of close-out connections are included on the aft flexure stacks that makes assembly possible, providing firm mechanical connections without interference.