Improved split pulse tube connecting line
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Solution Overview
Problem
Existing GM type pulse tube refrigerators experience losses and vibration transmission due to the connecting line separating the valve mechanism from the cold head, which affects cooling efficiency and vibration isolation, particularly at low temperatures and low speeds.
Innovation Solution
The connecting line is redesigned with a corrugated metal hose that allows bending at least 90 degrees, reduced internal void volume, and incorporates elastomer fillings and coatings to minimize void volume and absorb vibrations, along with a bendable tube and elastomer seals to prevent metal-to-metal contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a connecting line is used to separate the valve mechanism from the cold head, then vibration transmission is reduced, but cooling losses increase due to void volume and pressure drop
Solution Approach 1:
The patent employs a corrugated flexible hose instead of rigid tubing to connect the valve mechanism to the cold head. The corrugated structure provides flexibility that absorbs vibrations while maintaining a compact form factor with reduced internal void volume, thus minimizing both vibration transmission and cooling losses simultaneously.
Solution Approach 2:
The patent optimizes the geometric parameters of the corrugated hose, specifically the ratio of outside diameter to inside diameter (OD/ID ≥ 40% more), and controls the inner volume to be no greater than 33% of the core volume. These parameter changes reduce the void volume effect and pressure drop while maintaining vibration isolation capabilities.
2Adaptability or versatility
If a corrugated hose is used for the connecting line, then flexibility and vibration isolation are improved, but internal void volume increases causing greater losses
Solution Approach 1:
The corrugated flexible hose provides the necessary adaptability and vibration isolation while the optimized corrugation geometry (OD/ID ratio and convolution spacing) minimizes the internal void volume, reducing the trade-off between flexibility and cooling efficiency.
Solution Approach 2:
The connecting line uses a composite structure combining corrugated metal hose with elastomeric filler material. This composite design maintains flexibility and vibration isolation while the elastomer reduces the effective void volume, minimizing energy losses.
3Stability of the object's composition
If the connecting line is made rigid, then structural stability is improved, but vibration transmission increases
Solution Approach 1:
The corrugated flexible hose provides structural stability through its corrugated geometry and material properties while simultaneously isolating vibrations. The flexibility of the hose allows it to accommodate misalignments and movements without transmitting high-frequency vibrations to the cold head.
Solution Approach 2:
The corrugated hose acts as an intermediary element between the rigid valve mechanism and the cold head, providing both structural connectivity and vibration isolation. The flexible corrugated structure absorbs mechanical disturbances while maintaining the structural integrity of the connecting line.
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 design reduces losses and vibration transmission, maintaining cooling efficiency and improving vibration isolation, while allowing flexible mounting and reducing void volume and pressure drop.
Implementation Method 1
incorporates elastomer fillings and coatings to minimize void volume and absorb vibrations
Implementation Method 2
a bendable tube and elastomer seals to prevent metal-to-metal contact
Data Source
Figure 1
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Figure 4~5
AI summary
Losses in the connecting line between the Pressure Wave Generator and the cold head of a GM type pulse tube refrigerator, are reduced while maintaining or improving upon the desirable features of a standard corrugated hose connecting line including vibration isolation, separation distance, and mounting convenience. The basic means are to reduce the internal void volume of the convolutions in a corrugated hose in combination with reducing the number of corrugations, adding fillers to the void volumes, and vibration absorbing coatings.