Compliant Shaft Enclosure Support for Propeller Shaft Flexing
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Solution Overview
Problem
The existing anti-rotation mechanisms for oil distribution boxes in icebreakers fail due to flexing of the propeller shaft under heavy ice-breaking loads, leading to frequent repairs and operational interruptions.
Innovation Solution
A compliant shaft enclosure support system that includes a bar with slidably coupled longitudinal members and a link mechanism, allowing the oil distribution box to displace while limiting rotation of the propeller shaft, thereby absorbing flexing without constraining the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid anti-rotation bar is used to prevent rotation of the shaft enclosure, then rotation limitation is achieved, but the system fails under heavy ice-breaking loads due to shaft flexing
Solution Approach 1:
The patent transforms the static rigid anti-rotation bar into a dynamic system with multiple degrees of freedom. The bar can now rotate about its longitudinal axis and the connection points can pivot, allowing the structure to adapt to shaft flexing while maintaining anti-rotation functionality. This dynamic capability enables the system to accommodate large displacements without failure.
Solution Approach 2:
The patent changes the rotational parameters of the connection mechanisms. By allowing rotation about the longitudinal axis of the bar and pivoting at connection points, the system modifies its geometric parameters to accommodate shaft flexing. This parameter change enables the anti-rotation mechanism to remain effective while adapting to varying shaft positions under ice-breaking loads.
2Reliability
If the shaft enclosure is constrained to prevent rotation, then anti-rotation is achieved, but large displacements from shaft flexing cause failure
Solution Approach 1:
The system introduces dynamic movement capabilities to the anti-rotation bar through rotational joints and pivoting connections. This allows the bar to absorb and accommodate large displacements from shaft flexing without experiencing excessive stresses that would lead to failure, thereby maintaining system reliability under ice loads.
Solution Approach 2:
The patent designs the connection mechanisms with inherent movement capacity before loads are applied. The ability of the bar to rotate and connections to pivot acts as a pre-built cushioning mechanism that absorbs the shock and stress of ice-breaking loads, preventing catastrophic failure of the anti-rotation bar.
3Ease of operation
If a rigid connection system is used to limit rotation, then rotation control is precise, but the system requires frequent repairs due to failure under heavy loads
Solution Approach 1:
The dynamic design with rotational joints and pivoting connections allows the anti-rotation system to continuously operate under varying ice-breaking conditions. The mechanism adapts to shaft flexing in real-time, preventing failure and eliminating the need for frequent repairs, thereby improving ease of operation and continuous operation capability.
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 compliant system effectively minimizes the risk of damage to the anti-rotation bar and other components, reducing the need for repairs and maintaining continuous operation by absorbing large displacements caused by heavy ice-breaking loads.
Implementation Method 1
a bar having a first longitudinal member slidably coupled to a second longitudinal member
Implementation Method 2
the first longitudinal member having a first bar end of the bar configured to be rotatably connected to the shaft enclosure at a first connection to be rotatable relative to the shaft enclosure around the roll axis and around the pitch axis
Data Source
AI summary
In an example, a compliant shaft enclosure support system for coupling to a shaft enclosure surrounding a shaft includes a bar having a first member slidably coupled to a second member. The bar is oriented along the pitch axis of the shaft. A first bar end of the bar is rotatably connected, around the roll axis and pitch axis of the shaft, to the shaft enclosure at a first connection. A second bar end of the bar is rotatably connected, around the roll axis and pitch axis, to the structure at a second connection. A link is rotatably connected, around the roll axis, at a first link end to the bar, at an intermediate location spaced from the first and second bar ends. The link is rotatably connected, around the pitch axis, at a second link end to the shaft enclosure at a third connection spaced from the first connection.