Multi-Stage Seal Structure for Lubricating Oil Leak Containment
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Solution Overview
Problem
The existing seal devices for rotating machines, such as those in ship propulsion systems, face issues where high-pressure lubricating oil can leak out due to failure of seal rings, leading to contamination and inefficiency in preventing external fluids from entering the system.
Innovation Solution
A seal device with an intermediate seal part and a gas chamber, where a gas with higher pressure than the external fluid is supplied between the first and intermediate seal parts, and a lower-pressure gas is supplied between the intermediate and second seal parts, allowing the sealed fluid to be stored in the intermediate chamber in case of failure, preventing leakage and facilitating collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-pressure lubricating oil is supplied to the secondary annular chamber to blow out air and maintain sealing, then the response to seawater pressure fluctuations is improved, but the risk of lubricating oil leakage to the outside increases upon seal ring failure
Solution Approach 1:
The sealing system is divided into multiple independent seal rings (first, second, and third seal rings) arranged in sequence, with each seal ring forming a separate sealing stage. The pressure chambers are also segmented into first and second pressure chambers with different pressure levels, allowing isolation of leakage risks to specific segments rather than system-wide failure.
Solution Approach 2:
A low-pressure gas chamber is introduced as an intermediary between the high-pressure lubricating oil chamber and the external environment. This intermediate pressure zone acts as a buffer that prevents direct communication between the high-pressure sealed fluid and the external atmosphere, thereby containing potential leakage within the intermediate zone.
2Reliability
If the internal pressure in the secondary annular chamber is constantly adjusted to be higher than the primary annular chamber, then prevention of seawater entry is improved, but the severity of lubricating oil leakage worsens upon seal failure
Solution Approach 1:
The pressure control system is segmented into multiple pressure zones with different pressure levels. The first pressure chamber maintains high pressure for seawater exclusion, while the second pressure chamber operates at lower pressure, creating staged pressure reduction that limits the driving force for lubricating oil leakage to specific localized zones rather than enabling system-wide leakage.
Solution Approach 2:
The low-pressure gas chamber serves as an intermediary pressure zone between the high-pressure lubricating oil environment and atmospheric pressure. This intermediate zone reduces the pressure differential that drives leakage, thereby minimizing lubricating oil loss while still maintaining effective sealing against external fluids.
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 effectively prevents leakage of sealed fluids by maintaining differential pressures and allows for easy collection of any fluid that enters the intermediate chamber, ensuring reliable sealing and reducing the risk of contamination.
Implementation Method 1
a gas chamber is formed between the first seal part and the intermediate seal part, to which a gas having a higher pressure than the external fluid is supplied
Implementation Method 2
an intermediate chamber is formed between the intermediate seal part and the second seal part, to which a gas having a lower pressure than the gas supplied to the gas chamber and having a lower pressure than the sealed fluid is supplied
Data Source
AI summary
A seal device 1 includes first seal part facing an external fluid and second seal part arranged in parallel to the first seal part and facing a sealed fluid in an interior of equipment to prevent entry of the external fluid and leakage of a sealed fluid. Intermediate seal part is arranged in parallel to the first seal part and the second seal part between the first seal part and the second seal part. A gas chamber is formed between the first seal part and the intermediate seal part, to which a gas having a higher pressure than the external fluid is supplied. An intermediate chamber is formed between the intermediate seal part and the second seal part, to which a gas having a lower pressure than the gas supplied to the gas chamber and having lower pressure than the sealed fluid is supplied.