Split Stern Pipe Liner Assembly for Faster Replacement

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Solution Overview

Problem

The existing stern tube sealing systems require significant labor and effort for replacing the liner due to its single-piece cylindrical design, necessitating the removal of surrounding parts.

Innovation Solution

A split-type tubular member composed of multiple components that can be easily assembled and disassembled by aligning grooves and through holes along the axial direction, with bar members joining the components to facilitate installation and removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single-piece cylindrical liner is used, then the structural integrity and sealing performance are improved, but the installation and removal require significant labor and time

Engineering Contradiction:
Improvesealing performanceVSAvoidinstallation and removal time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The liner is divided into multiple segments that can be assembled together to form a complete cylindrical structure. Each segment can be independently installed and removed, significantly reducing the time and labor required for maintenance while maintaining the sealing performance through proper joint design between segments

Inventive Principle:
Principle #1Segmentation

2Device complexity

If a single-piece cylindrical liner is used, then the structural simplicity is improved, but the ease of maintenance and replacement deteriorates

Engineering Contradiction:
Improvestructural simplicityVSAvoidease of replacement
Core Design Contradiction:
Device complexityVSEase of repair

Solution Approach 1:

The liner structure is segmented into multiple sections that can be easily assembled and disassembled. This segmentation allows for quick replacement of worn or damaged sections without requiring complete removal of the entire liner, greatly improving maintenance ease while keeping the overall structure relatively simple

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The liner incorporates movable or adjustable components that allow for dynamic assembly and disassembly during maintenance operations, enabling quick replacement without complex removal procedures while maintaining structural simplicity during normal operation

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If surrounding parts are removed for liner replacement, then access to the liner is improved, but the labor hours and effort increase significantly

Engineering Contradiction:
Improveaccess to linerVSAvoidreplacement efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The liner is designed as separable segments that can be accessed and removed independently without requiring complete disassembly of surrounding parts. This segmentation allows maintenance personnel to access specific sections of the liner quickly, improving both ease of operation and replacement efficiency

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The liner segments are pre-configured with connection features that allow for quick attachment and detachment from surrounding structures. This preliminary design of connection mechanisms enables rapid access and replacement without extensive removal of surrounding parts, significantly improving productivity

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4699928A1Cylindrical member, method for assembling cylindrical member, method for disassembling cylindrical member, liner, stern pipe sealing system, and ship
Publication Date: 2026.02.25 WARTSILA JAPAN
  • EP4699928A1 patent drawingFigure 1
  • EP4699928A1 patent drawingFigure 2
  • EP4699928A1 patent drawingFigure 3

AI summary

A liner as an example of a tubular member includes a split-type tubular body structured by combining, in a circumferential direction of a propeller shaft, two components that are split along an axial direction of the propeller shaft; a pair of grooves provided, at the two components, along the axial direction on two connecting surfaces which face each other in the circumferential direction and which are in contact with each other, and forming a through hole, with a direction of an axis of the through hole being the axial direction, by aligning openings thereof at the connecting surfaces when the two connecting surfaces come into contact; and at least one bar member formed so as to extend along the axial direction and joining the two components by being inserted into the through hole. Cross-sectional shapes, in a cross section orthogonal to the axial direction, of the grooves are formed such that widths at a bottom surface side are greater than widths of the openings at the connecting surfaces.