Propeller Unit Damper Reinforcer for Bushing Wear Reduction
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Solution Overview
Problem
Existing outboard motor propeller units experience significant wear in bushings due to direct contact between protrusions, leading to increased vibration, unbalanced load on blades, and frequent replacement, especially in high-propulsion-force applications and vessels with unique hull shapes.
Innovation Solution
Incorporating a reinforcer made of a higher wear-resistant material, such as stainless steel, positioned between the bushing and propeller cylinder protrusions, which disperses friction and reduces direct contact wear, allowing for reduced wear and extended life of the bushing and damper components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bushing and propeller cylinder directly contact through protrusions, then rotational motion is transmitted effectively, but wear increases significantly due to rubbing and unbalanced loads
Solution Approach 1:
A reinforcer is introduced as an intermediary component between the bushing and propeller cylinder. This reinforcer absorbs and distributes the unbalanced loads and vibrations that occur during operation, preventing direct rubbing contact between the bushing and cylinder protrusions. The reinforcer acts as a mediator that maintains the functional connection while protecting the bushing from excessive wear.
Solution Approach 2:
The damper assembly uses composite construction with a bushing made of one material and a reinforcer made of a different material with superior wear resistance. This composite approach allows each component to be optimized for its specific function - the bushing for rotational movement and the reinforcer for load distribution and wear protection.
2Power
If protrusions contact directly to transmit rotational force, then power transmission is efficient, but friction causes increased wear and heat
Solution Approach 1:
The reinforcer serves as a mediator between the power transmission path of the protrusions and the bushing. It allows rotational force to be transmitted while distributing the frictional forces across a larger area, reducing the intensity of wear at any single contact point.
Solution Approach 2:
The reinforcer is pre-installed in position to intercept and manage frictional forces before they can cause significant wear to the bushing. It proactively handles the wear-generating contact, preserving the bushing for longer service life.
3Ease of manufacture
If bushing wears due to direct contact, then replacement is necessary, but frequent replacement increases maintenance time and cost
Solution Approach 1:
The reinforcer is designed as a sacrificial intermediary that protects the more expensive and time-consuming-to-replace bushing. By absorbing the wear, the reinforcer extends the maintenance interval significantly, reducing the frequency of service interruptions.
Solution Approach 2:
The reinforcer is designed as a consumable component with lower replacement cost and simpler installation compared to the bushing. It intentionally wears faster to protect the main bushing, acting as a disposable element that extends overall system life.
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 solution significantly reduces wear on bushing components, decreases the frequency of replacements, and enhances the mechanical strength and longevity of the damper, while maintaining performance by distributing friction and stress effectively.
Implementation Method 1
an elastic member disposed around a portion of the bushing different from the second pressing surface of the bushing in an axial direction and that elastically and deformably engages with the inner surface of the cylinder
Implementation Method 2
a reinforcer provided separately from the bushing and disposed between the first pressing surface and the second pressing surface
Data Source
AI summary
In an outboard motor, a damper includes a bushing fixed to a periphery of a propeller shaft. The damper includes a second pressing surface that presses a first pressing surface of an inner surface of a cylinder in a circumferential direction, an elastic member disposed around a portion of the bushing different from the second pressing surface of the bushing, and a reinforcer disposed between the first pressing surface and the second pressing surface.