Marine Propeller Hub Assembly With Pendulum Mass Torsional Damping
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Solution Overview
Problem
Existing solutions for reducing torsional vibrations in marine propeller hubs, such as passive rubber dampers, are not effective in filtering specific order-based vibrations and can lead to steering control and vessel handling problems.
Innovation Solution
A propeller hub assembly with a damper hub portion containing pendulum masses that oscillate to counteract torsional vibrations, allowing selective damping of particular orders without compromising steering and handling capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive rubber dampers are used to reduce torsional vibrations in marine propeller hubs, then vibration damping is provided, but steering control and vessel handling performance deteriorate
Solution Approach 1:
The patent applies local quality by making different parts of the hub assembly have different damping characteristics. The pendulum mass damper provides localized, frequency-specific damping at the hub, while the rest of the propulsion system maintains its natural vibration transmission characteristics for optimal steering and handling.
Solution Approach 2:
The patent changes the damping parameter from broad-spectrum passive rubber damper characteristics to frequency-selective pendulum damper characteristics. By adjusting the pendulum mass and suspension parameters, the system targets specific vibration orders while preserving handling qualities at other frequencies.
2Object-affected harmful factors
If passive rubber dampers are used to reduce torsional vibrations, then general vibration reduction is achieved, but specific order-based vibrations cannot be filtered
Solution Approach 1:
The patent applies local quality by making different parts of the hub assembly have different damping characteristics. The pendulum mass damper provides localized, frequency-specific damping at the hub, while the rest of the propulsion system maintains its natural vibration transmission characteristics for optimal steering and handling.
Solution Approach 2:
The patent changes the damping parameter from broad-spectrum passive rubber damper characteristics to frequency-selective pendulum damper characteristics. By adjusting the pendulum mass and suspension parameters, the system targets specific vibration orders while preserving handling qualities at other frequencies.
3Object-affected harmful factors
If a pendulum mass damper hub assembly is used to selectively dampen specific torsional vibrations, then noise and vibration are reduced, but device complexity increases
Solution Approach 1:
The patent merges the damper hub portion with the existing propeller hub structure, integrating the pendulum mass damper into the hub assembly rather than adding a separate external device. This combination reduces overall system complexity while maintaining selective vibration damping capabilities.
Solution Approach 2:
The damper hub portion serves multiple functions: it provides selective vibration damping, maintains structural integrity of the hub assembly, and allows free oscillation of pendulum masses. This multi-functionality reduces the need for additional separate components.
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 pendulum mass damper hub assembly effectively reduces noise and vibration, enhancing the operating environment for marine drive occupants by selectively damping specific torsional vibrations without degrading steering and handling performance.
Implementation Method 1
multiple pendulum masses located within the damper hub portion... Oscillations of the pendulum masses relative to the damper hub portion are configured to dampen torsional vibrations of the propeller hub assembly
Implementation Method 2
Oscillations of the pendulum masses relative to the damper hub portion are configured to dampen torsional vibrations of the propeller hub assembly
Data Source
AI summary
A propeller hub assembly for a marine drive having a propeller shaft is provided. The propeller hub assembly includes a first hub portion having a first main body and multiple propeller blades extending radially therefrom, a second hub portion, wherein the second hub portion is coupled to the first hub portion, and a damper hub portion, wherein the damper hub portion is coupled to the second hub portion. The propeller hub assembly further includes multiple pendulum masses located within the damper hub portion. The first hub portion, the second hub portion, and the damper hub portion are configured to engage the propeller shaft such that rotation of the propeller shaft causes rotation of the first hub portion, the second hub portion, and the damper hub portion. Oscillations of the pendulum masses relative to the damper hub portion are configured to dampen torsional vibrations of the propeller hub assembly.