Marine Drive Shaft Mechanical Seal with Water-Lubricated Flat Faces
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Solution Overview
Problem
Existing mechanical seal devices for drive shafts in vessels and watercrafts face issues with radial and angular misalignments, vibrations, corrosion of biasing means, complex assembly requirements, and potential leakage due to inadequate sealing and friction between annular sliding elements.
Innovation Solution
The mechanical seal device incorporates biasing means with springs on both stationary and rotary parts, housed in water-tight chambers with sealing rings for protection from seawater, and features calibrating pins for easy assembly, along with a centering sleeve for maintaining sealing and allowing drive shaft rotation in case of damage, and water circulation for lubrication and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If biasing means are exposed to seawater for long periods, then the mechanical seal device can maintain sealing pressure, but the biasing means suffer from corrosion
Solution Approach 1:
A corrosion-resistant intermediary component (corrosion-resistant biasing means or protective coating) is introduced between the biasing means and the seawater environment. This intermediary protects the biasing means from direct contact with corrosive seawater while maintaining the necessary sealing pressure function.
Solution Approach 2:
The biasing means are housed in a sealed, corrosion-resistant chamber or enclosure that creates a protected environment isolated from seawater. This inert environment prevents corrosion while allowing the biasing means to maintain sealing pressure on the sliding elements.
2Reliability
If annular sliding elements are tightly compressed to prevent leakage, then sealing improves, but friction and temperature increase leading to breaking risk
Solution Approach 1:
The compression parameter of the annular sliding elements is optimized to achieve the minimum necessary sealing pressure while avoiding excessive compression. This parameter adjustment balances sealing effectiveness with friction reduction, preventing temperature buildup and breaking risks.
Solution Approach 2:
A water lubrication system is introduced between the annular sliding elements to reduce friction. The hydraulic film of water allows the sliding elements to maintain contact for sealing while significantly reducing friction and heat generation, preventing breakdown.
3Strength
If annular sliding elements are insufficiently compressed to reduce friction, then breaking risk decreases, but separations occur causing leakage
Solution Approach 1:
A water lubrication and pressurization system is introduced to maintain optimal contact pressure between annular sliding elements. The hydraulic pressure ensures consistent sealing contact while the lubricating water film reduces friction, preventing both separations and excessive compression.
Solution Approach 2:
A feedback mechanism is implemented to monitor and adjust the compression force on annular sliding elements in real-time. This feedback system ensures the sliding elements maintain optimal contact pressure for sealing while preventing excessive compression that could lead to breaking.
4Manufacturing precision
If mechanical seal device uses complex assembly structure for proper positioning, then sealing precision improves, but assembly complexity and specialization requirements increase
Solution Approach 1:
Positioning features such as calibrated pins and guide elements are pre-installed or pre-positioned during manufacturing. This preliminary action ensures proper positioning of annular sliding elements is automatically achieved during assembly, reducing assembly complexity while maintaining positioning precision.
Solution Approach 2:
Standardized, modular components with uniform positioning features are used throughout the mechanical seal device. This homogenization of design allows for simplified assembly procedures while maintaining precise positioning, reducing the need for specialized workers.
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 ensures effective compensation for misalignments and vibrations, reduces corrosion, simplifies assembly, and enhances sealing and durability, preventing leakage and allowing the drive shaft to rotate even with minor damage.
Implementation Method 1
both said stationary part and said rotary part are provided with biasing means urging said stationary annular sliding element and said rotary annular sliding element respectively towards each other
Implementation Method 2
said biasing means are composed of one or more springs
Implementation Method 3
Said biasing means are contained into water-tight chambers formed by at least two sealing rings for each annular sliding element
Implementation Method 4
said at least two sealing rings are arranged so as to generate an elastic damping system
Implementation Method 5
said at least two sealing rings are arranged so as to generate an elastic damping system
Implementation Method 6
the two contact faces being in coplanar relationship and in contact with each other
Implementation Method 7
Water circulation for lubrication and cooling
Implementation Method 8
the annular sliding elements guarantee the sealing effect and the relative rotation between the two parts by means of the flat contact surfaces that slide one on each other
Data Source
Figure 1
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Figure 3
AI summary
A mechanical seal device for a drive shaft extending through an opening in the hull of a watercraft, said device being adapted to prevent leakage of water into said hull through said opening, which device comprises a stationary part (1) coupable to the hull and a rotary part (2), rotatably coupled to the stationary part (1) and integrally connected to the drive shaft. The stationary part (1) and the rotary part (2) are provided with a stationary annular sliding element (10) and a rotary annular sliding element (20) respectively, which annular sliding elements (10, 20) are each provided with a flat contact face (100, 200) the two contact faces (100, 200) being in coplanar relationship and in contact with each other. Both the stationary part (1) and the rotary part (2) are provided with biasing means for urging the stationary annular sliding element (10) and the rotary annular sliding element (20) respectively towards each other.