Soy-Based Foam Liner for Propeller Shaft Vibration Damping
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Solution Overview
Problem
Conventional dampeners for rotating tubular members, such as propeller shafts, fail to adequately reduce noise, vibration, and harshness (NVH) while also being too heavy, which is a concern for improving fuel economy and reducing rotational mass.
Innovation Solution
A propeller shaft assembly incorporating a viscoelastic, natural oil polyol-based foam liner, specifically a soy-based foam, is used to reduce vibration amplitudes and noise, offering improved damping and reduced mass compared to traditional foam liners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional foam liners are used to dampen propeller shaft vibrations, then vibration damping is achieved, but the weight of the shaft assembly increases significantly
Solution Approach 1:
The patent changes the material parameters of the foam liner by using a lower density foam (30-60 ppi cell structure) compared to conventional foams. This parameter change allows the foam to maintain vibration damping properties while reducing the mass of the liner and overall shaft assembly weight.
Solution Approach 2:
The patent employs a composite approach by combining the foam liner with the propeller shaft in a specific configuration. The foam material itself is a composite structure with controlled cell density and distribution, allowing optimization of both damping performance and weight reduction simultaneously.
2Reliability
If high density foam is used to reduce vibration, then damping performance improves, but the mass of the dampener increases
Solution Approach 1:
The patent specifically changes the density parameter of the foam material, using a lower density range (30-60 ppi) compared to conventional high density foams. This parameter optimization enables the foam to provide adequate damping performance with reduced material quantity and lower mass.
Solution Approach 2:
The patent applies foam with specific local characteristics - the cell structure and density are optimized for the specific damping requirements of the propeller shaft application. The foam is configured to provide adequate damping at critical locations without requiring uniform high density throughout, thus reducing overall mass.
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 soy-based foam liner effectively dissipates energy during vibrations, significantly reducing NVH and weight, outperforming conventional materials like cardboard and traditional foams in damping efficiency and mass reduction.
Implementation Method 1
The foam liner member is made of a viscoelastic, natural oil polyol-based foam, whereby the foam liner member is operable to reduce vibration amplitudes occurring within the propeller shaft member
Implementation Method 2
the foam liner member is operable to reduce vibration amplitudes occurring within the propeller shaft member relative to an undampened propeller shaft member
Data Source
Figure 1~3
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Figure 6A~6B
AI summary
A propeller shaft assembly having a propeller shaft member defining an inner volume. A foam liner member is disposed in at least a portion of the inner volume of the propeller shaft member. The foam liner member is made of a viscoelastic, natural oil polyol-based foam, whereby the foam liner member is operable to reduce vibration amplitudes occurring within the propeller shaft member relative to an undampened propeller shaft member.