Propeller Shaft Seal Arrangement with Pressure Differential Control
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Solution Overview
Problem
Existing propeller shaft sealing arrangements for vessels are complex, require numerous components, and have limitations in ease of maintenance and redundancy, leading to inefficiencies and increased costs.
Innovation Solution
A simplified sealing arrangement using a water seal and an oil seal with an intermediate air-filled compartment, equipped with pressure sensors and an air pressure system to maintain a pressure lower than seawater pressure, allowing for the use of commercially available seals and enabling easy replacement and redundancy, reducing component count and operational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional multi-component sealing arrangement is used, then sealing reliability is improved, but device complexity increases and maintenance difficulty increases
Solution Approach 1:
The patent combines the water seal and oil seal functions into a single integrated sealing arrangement. The water seal and oil seal are positioned adjacent to each other within the same intermediate compartment, eliminating the need for separate housing units and reducing the overall number of components while maintaining both sealing functions simultaneously
Solution Approach 2:
The intermediate compartment serves multiple functions: it houses both the water seal and oil seal, provides a common chamber for pressure equalization, and facilitates easier maintenance access. This multi-functional design reduces the need for additional specialized components for each sealing function
2Reliability
If a traditional sealing arrangement with multiple housing units is used, then sealing reliability is improved, but ease of repair deteriorates
Solution Approach 1:
By housing both water and oil seals within a single intermediate compartment rather than separate housing units, the patent enables simultaneous access to both seal types during maintenance operations, significantly improving ease of repair while maintaining dual sealing functionality
3Reliability
If pressure equalization systems are added to reduce pumping phenomena, then operational reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines the pressure equalization function with the intermediate compartment that houses the seals. The compartment itself serves as the pressure equalization chamber, eliminating the need for separate pressure control systems or additional components while reducing pumping phenomena between the water seal and oil seal
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 solution reduces the number of components needed, minimizes pumping phenomena, facilitates easier maintenance, and provides redundancy, resulting in a more cost-effective and reliable sealing system that can maintain operation even in emergency situations.
Implementation Method 1
an air pressure system for producing a pressure to the air in the intermediate compartment, whereby the pressure of the air within the intermediate compartment is kept at a lower level compared to the pressure of the sea water acting on the propeller shaft
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The propeller shaft (31) supported with at least one bearing (41) extends through an opening (O1) in the hull of the vessel to the propeller (32). The seal arrangement comprises a water seal (100) positioned on the propeller shaft (31) adjacent to the opening (O1) and a first oil seal (200) positioned on the propeller shaft (31) at an axial (X-X) distance from the water seal (100) adjacent to the bearing (41). An intermediate compartment (300) surrounds the water seal (100) and the first oil seal (200). A first pressure sensor (91) measures the pressure of the sea water acting at the propeller shaft (31) and a second pressure sensor (92) measures the pressure within the intermediate compartment (300). An air pressure system (500) produces an air pressure into the intermediate compartment (300), whereby the air pressure within the intermediate compartment (300) is kept at a lower level compared to the pressure of the sea water acting on the propeller shaft (31).