Boat Propulsion Cowling Support Portion Thickness Design
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Solution Overview
Problem
The existing boat propulsion devices face a drawback in the strength of the support portion due to its thin thickness, which is necessary to prevent dents from molding shrinkage, leading to potential structural weaknesses.
Innovation Solution
A boat propulsion device design featuring a support portion with a small thickness section and a large thickness section, where the large thickness section is continuous with the small thickness section and includes an attachment surface for the lock portion, enhancing the structural integrity while preventing dents from molding shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the support portion is entirely formed with a small thickness, then dents attributed to molding shrinkage are prevented in the bottom cowling, but the strength of the support portion itself is degraded
Solution Approach 1:
The support portion is designed with non-uniform thickness, featuring a thin section (first thickness) at the joint area to prevent molding shrinkage dents and a thick section (second thickness greater than the first) at the lock portion attachment area to provide structural strength. This local variation in thickness allows each region to optimize for its specific functional requirement.
2Strength
If the support portion has a large thickness, then the strength of the support portion is improved, but dents from molding shrinkage are more likely to be produced in the bottom cowling
Solution Approach 1:
The support portion incorporates a thick section (second thickness) specifically at the lock portion attachment area to provide the necessary structural strength and load-bearing capacity, while maintaining a thin section (first thickness) at the joint area to prevent molding shrinkage dents. This localized thickening ensures strength where needed without compromising the bottom cowling surface.
3Device complexity
If the support portion is made with uniform thin thickness, then manufacturing complexity is reduced, but the strength required for supporting the coupling mechanism is insufficient
Solution Approach 1:
The support portion features a non-uniform thickness design with a thin section (first thickness) at the joint area for easy molding and a thick section (second thickness) at the lock portion attachment area for structural strength. This design maintains manufacturing feasibility while providing the necessary strength to support the coupling mechanism.
Solution Approach 2:
The support portion is segmented into distinct functional zones with different thickness characteristics: a thin-section joint area for easy manufacturing and dent prevention, and a thick-section lock portion attachment area for structural strength. This segmentation allows each zone to be optimized independently for its specific function.
Data Source
AI summary
A boat propulsion device includes an engine including a crankshaft extending in an up-and-down direction and a cowling accommodating the engine. The cowling includes a first cowling portion preferably made of resin, a second cowling and a coupling mechanism configured to couple the first cowling portion to the second cowling portion. The coupling mechanism includes a first lock portion and a second lock portion. The first lock portion is attached to the first cowling portion. The second lock portion is attached to the second cowling portion and locks with the first lock portion. The first cowling portion includes a cowling main body and a support portion. The support portion preferably has a plate shape. The support portion is erected on an inner surface of the cowling main body, supports the first lock portion, and includes a small thickness section and a large thickness section.