Cryocooler Link Flexure for Misalignment and Vibration Reduction
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Solution Overview
Problem
Cryocooler systems experience vibrations and noise due to piston drive couplings, which degrade image quality and lead to mechanical failures and reduced cooling capacity, as tight mechanical tolerances exacerbate misalignment-induced bending stresses and frictional heat buildup.
Innovation Solution
A cryocooler link flexure with flattened opposing faces orthogonal to the longitudinal axis of connecting pins accommodates misalignment between the motor shaft and regenerator piston, allowing for tight clearances while minimizing stress and friction through flexibility, using materials like titanium for enhanced vibration and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical joint fit tolerances are tightened to reduce excess play and noise, then vibration and noise are reduced, but bending stresses increase due to misalignment leading to link failure
Solution Approach 1:
The regenerator link is designed with a flexible section comprising a thin-walled tubular structure that can bend to accommodate misalignment between the motor shaft and regenerator piston. This flexible section acts like a thin-walled shell that absorbs misalignment stresses through elastic deformation, preventing catastrophic link failure while maintaining tight mechanical tolerances for reducing vibration and noise.
Solution Approach 2:
The link geometry is changed by introducing a flexible section with specific dimensional parameters (reduced wall thickness, optimized length-to-diameter ratio) that allow controlled bending. This parameter change enables the link to tolerate misalignment-induced stresses without exceeding material strength limits, resolving the contradiction between tight tolerances and stress resistance.
2Reliability
If mechanical joint fit tolerances are tightened to reduce excess play, then coupling looseness is reduced, but misalignment-induced bending stresses increase causing material fatigue
Solution Approach 1:
The flexible section of the regenerator link uses a thin-walled tubular structure that provides both coupling stability (through tight tolerances) and fatigue resistance (through elastic compliance). The flexible section absorbs misalignment stresses through repeated elastic deformation cycles, preventing material fatigue and extending link service life while maintaining reliable coupling.
Solution Approach 2:
The flexible section acts as a pre-designed stress-absorbing element that cushions against misalignment-induced bending stresses before they can cause material fatigue. By incorporating this compliant element in advance, the design protects the rigid link sections from fatigue loading, extending the overall service life of the coupling mechanism.
3Object-affected harmful factors
If tight clearances are used in mechanical couplings, then excess play is reduced, but frictional heat buildup increases due to cylinder wall rubbing
Solution Approach 1:
The flexible section of the regenerator link acts as a compliant coupling that accommodates misalignment without transmitting it to the expander displacer. By absorbing misalignment through elastic bending, the flexible section prevents the displacer from rubbing against cylinder walls, eliminating frictional heat buildup and maintaining cold end temperature despite tight clearances in the coupling joints.
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 flexible link design reduces noise, minimizes heat buildup, and enhances cooling capacity by accommodating misalignment without inducing excessive stress, leading to improved reliability and reduced vibration-induced failures.
Implementation Method 1
a link flexure having a proximal end coupled by a first pin to the drive coupler and having a distal end coupled by a second pin to the regenerator piston
Data Source
AI summary
A cryocooler is provided that includes: a regenerator piston; a drive coupler; and a link flexure having a proximal end coupled by a first pin to the drive coupler and having a distal end coupled by a second pin to the regenerator piston, where the link flexure forms a vane having flattened opposing faces that are orthogonal to a longitudinal axis for the first and second pin.