Propeller Hub Interference Fit for Compact Underwater Drive
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Solution Overview
Problem
Conventional propeller drives require larger propeller hubs due to the need for feet on propeller blades, limiting the number of blades that can be accommodated or the size of the hub, which is a disadvantage in compact designs such as those for underwater vehicles.
Innovation Solution
The propeller blades are attached to the propeller hub using cap screws from the inside, eliminating the need for external feet and allowing for a smaller hub diameter or more blades with the same hub size, with a pressurized oil interference fit between the hub and sleeve for torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If propeller blades are attached from the outside with feet protruding beyond the outer contour, then the screw connection can be made, but the propeller hub outer diameter becomes large
Solution Approach 1:
The patent inverts the conventional attachment approach by screwing propeller blades to the propeller hub from the inside rather than from the outside. The fastening elements are introduced through the drive shaft and propeller hub from the interior side, eliminating the need for feet protruding beyond the outer contour of the propeller blade. This inversion allows the propeller hub to have a smaller outer diameter while maintaining secure blade attachment.
2Length of stationary object
If the propeller hub outer diameter is reduced, then compactness is improved, but the number of propeller blades that can be accommodated is limited
Solution Approach 1:
By inverting the attachment direction to screw from the inside, the patent enables a smaller propeller hub outer diameter to accommodate the same number of propeller blades or more blades with the same hub size, resolving the contradiction between compactness and blade capacity.
Solution Approach 2:
The patent changes the dimensional approach by utilizing the interior space of the propeller hub and drive shaft for the fastening operation. Instead of extending outward in the radial dimension with feet, the attachment mechanism operates from the interior, effectively using the axial and radial space inside the hub to achieve secure blade fixation without increasing the outer diameter.
3Ease of manufacture
If feet protrude beyond the outer contour of the propeller blade, then screw attachment is enabled, but the propeller hub requires larger dimensions
Solution Approach 1:
The patent eliminates the need for protruding feet by inverting the attachment approach. Fastening elements are introduced from the inside of the propeller hub through the drive shaft, securing the propeller blades without requiring additional volume outside the hub contour. This maintains blade attachment capability while reducing overall hub volume.
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 design enables a smaller propeller hub or more blades with the same hub size, enhancing compactness and torque transmission reliability, particularly suitable for underwater vehicles.
Implementation Method 1
a pressurized oil interference fit between the hub and sleeve for torque transmission
Implementation Method 2
pressurized oil interference fit
Implementation Method 3
The head screws are guided from the inside of the propeller hub through the through holes formed in the propeller hub and screwed into the blind holes formed in the propeller blades
Data Source
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AI summary
The invention relates to a drive device equipped with a drive shaft and a propeller which is arranged on said drive shaft. The propeller comprises a propeller hub connected to the drive shaft, and at least two propeller vanes that are detachably secured to said propeller hub. These are screwed to the propeller hub, proceeding from a propeller hub inner side which faces the drive shaft, using cap screws.