Pipe Fitting Sealing with C-Shaped Metal Seal and O-Rings
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Solution Overview
Problem
Conventional pipe joints for car air-conditioner compressors experience gas leakage when using carbon dioxide as refrigerant due to O-ring failure, and replacing O-rings with metal seals requires excessive tightening force, complicating the fixing operation.
Innovation Solution
A pipe joint design featuring a metal seal with a C-shaped cross-section, a first O-ring between the fitting and flange, and a second O-ring between the flange and body, along with a projecting portion on the flange, allows for secure sealing with reduced tightening force, preventing gas leakage and facilitating easy material compatibility and installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal seal is used instead of an O-ring to prevent gas leakage, then sealing reliability is improved, but the tightening force required increases and fixing operation becomes more complex
Solution Approach 1:
The sealing function is segmented into two independent components: an O-ring for external sealing and a metal seal for internal sealing. This segmentation allows each sealing component to be optimized for its specific function without requiring excessive tightening force, as the O-ring handles the primary sealing task while the metal seal provides reinforcement.
Solution Approach 2:
The O-ring acts as an intermediary element between the fitting and flange, providing a compliant sealing interface that reduces the tightening force needed to seat the metal seal. This intermediary soft seal allows the metal seal to be installed without requiring excessive clamping force that would complicate the fixing operation.
2Reliability
If a metal seal is used to seal high-pressure gas, then gas leakage prevention is improved, but more than two bolts are required increasing the number of man-hours
Solution Approach 1:
The sealing system is divided into external sealing (O-ring) and internal sealing (metal seal) functions. The O-ring handles the majority of the sealing requirement, allowing the metal seal to be a simpler component that can be secured with minimal fasteners, thus reducing assembly time and man-hours.
Solution Approach 2:
The O-ring serves as a simple, replaceable component that provides sufficient sealing for the application. By using this simpler sealing element in conjunction with the metal seal, the overall assembly time is reduced as the O-ring can be quickly installed and removed without requiring complex fastening procedures.
3Reliability
If a metal seal is used instead of an O-ring, then high-pressure gas sealing is improved, but the tightening force required deteriorates fixing operation
Solution Approach 1:
The sealing task is divided between the O-ring which handles external sealing with minimal tightening force, and the metal seal which provides internal sealing reinforcement. This segmentation allows the tightening operation to be performed with standard torque values, maintaining ease of operation while achieving high-pressure gas sealing.
Solution Approach 2:
The sealing mechanism transitions from relying solely on high tightening force (metal seal only) to a dual机制 where the O-ring provides sealing at lower contact pressures. This parameter change in the sealing approach allows the metal seal to be installed with standard tightening forces, preserving ease of operation.
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 design effectively prevents high-pressure gas leakage and enhances operational workability by using a metal seal that accumulates resilient repulsion force, allowing for secure sealing with minimal tightening force and preventing material corrosion.
Implementation Method 1
a metal seal is composed of a ring member having a 'C' shaped cross section, which includes an opening groove in an inner circumference; said O-ring comprises a first O-ring provided between said fitting and said flange, and a second O-ring provided between said flange and said body
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A pipe joint 1 comprises a fitting 10 connected with a hose 2, a flange 20 pressingly holding the fitting 10 inserted into a through hole 21 toward a block 3, a bolt 30 for fixing tightly the flange 20 to the block 3, a metal seal 40 having "C" cross section so as to seal a joined portion of a communication passage 11 and a connection opening 3a externally, and a first and a second O-rings 50, 60 so as to seal a contact portion of the fitting 10 and the block 3. A projecting portion 24 is formed on a lower face 23 of the flange 20, the projection portion 24 is formed at an area opposite to an area where the insertion hole 21 is formed with respect to a center axis of the through hole 21, the project portion 24 projects from other portion of the flange towards the block 3. A tip of the fitting 10 inserted into the through hole 21 projects towards the block 3 from the lower face 23 of the flange 20.