Dual-Flange Pipe Joint Sealing for CO2 Refrigeration
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Solution Overview
Problem
Refrigerating cycle systems using CO2 as a refrigerant face challenges with high-pressure sealing due to the inability of traditional rubber sealing members to maintain air tightness at low temperatures and prevent refrigerant leakage, as they are either distorted by external shocks or permeable to CO2.
Innovation Solution
A pipe connecting structure featuring a male and female flange block configuration with a dual-sealing mechanism, utilizing a soft metal inner sealing part and a high-elasticity rubber outer sealing part, along with beads and grooves for enhanced sealing, to increase the hardness and air tightness at joints, preventing refrigerant leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rubber sealing members (ACM or EPDM) are used in CO2 refrigerating cycle systems, then the sealing structure is simple and easy to manufacture, but the sealing members cannot bear high pressure, are distorted by external shocks at low temperatures, or suffer from CO2 permeation, leading to refrigerant leakage
Solution Approach 1:
The sealing member is constructed as a composite structure with an inner sealing part made of soft metal (such as lead, tin, zinc, or their alloys) and an outer sealing part made of high-elasticity rubber (such as polybutadiene, polyisoprene, or styrene-butadiene rubber). The soft metal inner sealing part provides resistance to high pressure and CO2 permeation, while the rubber outer sealing part provides high elasticity to absorb external shocks. This composite material approach resolves the contradiction by combining materials with complementary properties to achieve reliable sealing under high pressure and varying temperatures without requiring a complex multi-component structure.
Solution Approach 2:
The sealing member applies local quality by using different materials for different parts of the sealing structure. The inner sealing part that directly contacts the high-pressure CO2 refrigerant is made of soft metal to prevent permeation and withstand pressure, while the outer sealing part that faces external shocks is made of high-elasticity rubber to absorb impact. This localized material differentiation allows each part to perform its specific function optimally, achieving reliable sealing without overall structural complexity.
2Reliability
If rubber sealing members are used to provide elasticity at low temperatures, then the sealing structure is simple, but the sealing members are distorted by external shocks and cannot maintain air tightness
Solution Approach 1:
The sealing member combines soft metal inner sealing part with high-elasticity rubber outer sealing part to resolve the contradiction between air tightness and shock resistance. The soft metal provides dense, impermeable sealing that maintains air tightness, while the rubber outer layer provides elasticity to absorb external shocks without transmitting them to the inner sealing part. This composite structure ensures that air tightness is maintained even under external shock conditions.
Solution Approach 2:
The high-elasticity rubber outer sealing part acts as a cushioning layer that absorbs external shocks before they reach the inner sealing part. This beforehand cushioning prevents the soft metal inner sealing part from being distorted by external impacts, thereby maintaining air tightness. The rubber layer is specifically designed to be highly elastic to provide this protective cushioning effect.
3Reliability
If sealing members are designed to withstand high pressure, then the sealing structure becomes more robust, but the sealing members deform or create gaps under external shock at low temperatures
Solution Approach 1:
The sealing member uses a composite structure where the soft metal inner sealing part provides high pressure bearing capacity while the rubber outer sealing part provides shock absorption. The soft metal's density and impermeability allow it to withstand high CO2 pressure without deforming, while the rubber outer layer's elasticity absorbs external shocks, preventing them from transmitting to the inner sealing part. This division of functions maintains sealing member integrity under both high pressure and external shock conditions.
Solution Approach 2:
The sealing member applies local quality by making the inner sealing part dense and impermeable to withstand high pressure, while the outer sealing part is made highly elastic to absorb shocks. This localized functional differentiation allows the sealing member to simultaneously achieve high pressure bearing capacity and resistance to external shock without compromising overall integrity.
4Reliability
If EPDM rubber sealing members are used to prevent refrigerant leakage, then the sealing structure is simple, but CO2 permeation occurs causing refrigerant leakage
Solution Approach 1:
The sealing member replaces EPDM rubber with a composite structure where the inner sealing part is made of soft metal (such as lead, tin, zinc, or their alloys) that is impermeable to CO2. The soft metal's dense atomic structure prevents CO2 molecules from permeating through, eliminating the permeation issue inherent in rubber materials. The rubber outer sealing part maintains the simple sealing structure while the soft metal inner part provides the impermeable barrier.
Solution Approach 2:
The invention changes the material parameter of the inner sealing part from organic rubber (EPDM) to soft metal, fundamentally altering the permeability characteristic. The soft metal's much lower permeability to CO2 compared to rubber materials eliminates the harmful permeation effect while maintaining the sealing function. This parameter change in material density and molecular structure directly addresses the CO2 permeation problem.
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 solution effectively maintains air tightness under high pressures and varying temperatures without deforming the sealing members, preventing CO2 permeation and refrigerant leakage, while ensuring ease of assembly and durability.
Implementation Method 1
A pipe connecting structure featuring a male and female flange block configuration with a dual-sealing mechanism, utilizing a soft metal inner sealing part and a high-elasticity rubber outer sealing part
Implementation Method 2
high-elasticity rubber outer sealing part
Implementation Method 3
preventing CO2 permeation and refrigerant leakage
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention provides a pipe connecting structure including a male flange block (24) combined with a first pipe (22) and a female flange block (28) combined with a second pipe (26), which is fastened to the male flange block (24) by fastening means (30,32), where a protrusion (24a) having a hole (H1) that communicates with the first pipe (22) is formed through the male flange block (24), and an insert portion (28a) into which the protrusion (24a) is inserted is formed through the female flange block (28), and a sealing member (34) to closely contact with the end face (24b) of the protrusion (24a) is seated on the bottom (28b) inside the insert portion (28a), and the sealing member (34) includes an inner sealing part (34a) of soft metal and an outer sealing part (34b) of rubber tightly fitted around the outer circumference of the inner sealing part (34a). Therefore joints between pipes, a heat exchanger and a pipe, or two components can bear high pressures in a refrigerating cycle system using a CO2 refrigerant, air tightness can be maintained under low and high temperatures without changes in quality and shape of a sealing members, and it is possible to prevent and minimize leakage of the refrigerant by preventing permeation of CO2.