Hollow Cycloidal Marine Propulsion for Easier Blade Maintenance
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Solution Overview
Problem
Cycloidal marine propulsion units face challenges in serviceability and reliability, particularly with complex structures and the need for improved maintenance access and reduced maintenance requirements due to their critical nature and new applications in marine vessels.
Innovation Solution
A hollow rotary casing design that encloses the blade shaft portions, allowing maintenance access from the hull, with a power transmission system engaging the outer circumference of the casing, and a main bearing arrangement that enables rotation and thrust transmission while allowing for servicing within the casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If conventional cycloidal propulsion units use a solid rotor structure with blades mounted on the perimeter, then structural strength is maintained, but maintenance access to critical blade components becomes difficult requiring vessel dry-docking
Solution Approach 1:
The patent applies nesting by placing the blade assembly and its support structure inside a hollow rotary casing. The hollow casing acts as a container that encloses the blade shaft portions and associated components, allowing maintenance personnel to access these critical parts from the interior of the casing without requiring vessel dry-docking. This nested configuration resolves the contradiction by providing easy maintenance access while maintaining structural integrity through the rigid hollow casing design.
2Reliability
If separate cooling systems are used for the rotor and bearing arrangements, then cooling effectiveness is improved, but the number of components and system complexity increases
Solution Approach 1:
The patent merges the cooling function into a single integrated seawater flow system that serves multiple components. Seawater flows through the hollow rotary casing to cool the rotor, then continues to cool the bearing arrangements, and finally exits through the support structure. This unified cooling approach maintains effective thermal management for all critical components while reducing system complexity by eliminating the need for separate cooling systems for the rotor and bearings.
3Duration of action of stationary object
If periodic maintenance of seals and lubricants is required, then component longevity is maintained, but operational downtime and maintenance requirements increase
Solution Approach 1:
The patent implements self-service through a sealed maintenance-free bearing arrangement that eliminates periodic maintenance requirements. The hollow rotary casing is equipped with seals that prevent water ingress into the bearing compartments, allowing the bearings to operate without periodic lubrication or maintenance for extended periods. This self-service design significantly reduces operational downtime and maintenance requirements while maintaining component longevity through protective sealing and proper lubrication containment.
Data Source
AI summary
A cycloidal marine propulsion unit, including a hollow rotary casing having a central axis and defining a central inner space with an opening at an axial end thereof. A mounting body rotatably supports the rotary casing on a hull of a marine vessel. A rotating arrangement is provided for rotating said hollow rotary casing, while a plurality of blades extend axially from the rotary casing away from the hull. Each blade is mounted for pivotal movement with respect to the rotary casing, about respective blade axes. The rotating arrangement is configured to rotate the rotary casing by a circumference thereof. A blade shaft portion of each blade is at least partly received within the central inner space so as to attach said blade to the rotary casing.