Marine Propeller Hub Cap with Connection Ring
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Solution Overview
Problem
The large diameter of propeller hubs in marine vessels creates a hydrodynamically inefficient hub vortex, reducing thrust and increasing fuel consumption, and existing hub caps are difficult to install on controllable pitch propellers with hydraulic actuating means due to space constraints.
Innovation Solution
A novel hub cap design featuring a separate circular connection ring coaxial with the hub body, fastened to the hub cap using dowels and bolts, allowing for easy installation from outside the hub cap, and a method involving producing a connection ring with matching diameters and holes for secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a hub cap is arranged to cover the radial difference between the hub and hydraulic cylinder, then hydrodynamic efficiency is improved, but fastening from inside becomes impossible requiring external fastening
Solution Approach 1:
The hub cap assembly is segmented into multiple components: the hub cap itself, a separate connection ring, and external fastening elements (bolts/nuts). This segmentation allows the hub cap to be fastened from outside the propeller hub, solving the accessibility problem while maintaining the hydrodynamic efficiency gained from the streamlined design that covers the radial difference between hub and hydraulic cylinder.
2Strength
If the hub diameter is large to accommodate blade roots, then structural strength is improved, but hydrodynamic efficiency deteriorates due to hub vortex formation
Solution Approach 1:
The hub cap is designed with a streamlined, converging shape that transforms the harmful hub vortex into a beneficial flow pattern. By covering the radial difference between the hub and hydraulic cylinder with a smooth surface, the design converts the energy loss from vortex formation into improved hydrodynamic efficiency, reducing the adverse pressure gradient while maintaining the large hub diameter needed for structural strength.
3Productivity
If a streamlined hub cap design is used to improve hydrodynamics, then thrust efficiency is improved, but installation complexity increases due to space constraints
Solution Approach 1:
The hub cap assembly is divided into separate components (hub cap, connection ring, fastening elements) that can be manufactured independently and assembled externally. This segmentation simplifies installation by allowing workers to attach the hub cap from outside the propeller hub, avoiding the need to disassemble the tight internal space containing the hydraulic cylinder, thereby maintaining thrust efficiency while reducing installation complexity.
Solution Approach 2:
A separate connection ring is introduced as an intermediary component between the hub cap and the propeller hub. This connection ring provides a mounting interface that allows the streamlined hub cap to be securely fastened from outside the hub, simplifying the installation process while preserving the hydrodynamic benefits of the streamlined design.
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 solution results in a simple, lightweight, and cost-effective hub cap installation that enhances thrust efficiency and reduces fuel consumption by eliminating the hub vortex, while providing a modern and efficient fastening mechanism for existing propellers.
Implementation Method 1
fastening the connection ring to the hub cap by means of dowels pressed in coaxial radial holes in the hub cap and in the connection ring, respectively
Implementation Method 2
fastening the connection ring to the hub cap by means of dowels pressed in coaxial radial holes
Implementation Method 3
the hole in the hub cap has a threaded section and the hole is closed and sealed by means of a plug threaded in the threaded section of the hole
Implementation Method 4
the hole is closed and sealed by means of a plug threaded in the threaded section of the hole
Implementation Method 5
The problem relating to the hub vortex has been attempted to be solved by arranging a hub cap to the downstream end of the hub, and fins on the hub cap, both the hub cap and the fins rotating together with the propeller
Implementation Method 6
the hub cap may be a cylindrical extension of the hub, but normally it is a converging extension. The convergence may be either conical or curved
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The present invention relates to a novel propeller for a marine vessel and a method of installing the hub cap to the hub. More specifically, the present invention relates to hub caps for use in connection with both fixed pitch and controllable pitch propellers. The propeller of the invention comprises a hub with a hub body (42), propeller blades, and a hub cap (66), the hub cap (66) having an outer surface provided with fins, and being fastened to the aft end of the hub body (42) by means of a connection ring (72).