Sterndrive Coupler Rebuildability With Polyurethane Dampers
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Solution Overview
Problem
Current sterndrive couplers are not repairable, prone to premature failure due to worn splines and rubber dampening material, and limited to 600 ft-lbs of torque, leading to costly replacements and potential propulsion loss.
Innovation Solution
A field-serviceable coupler with a splined central shaft and polyurethane dampening material, allowing for replacement of worn components like splines and dampeners, and an external indicator for maintenance needs, capable of handling at least 1,200 ft-lbs of torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welded construction is used for sterndrive coupler, then manufacturing strength is improved, but repairability deteriorates
Solution Approach 1:
The coupler is divided into separate modular components including a drive shaft, dampener assembly, and housing that can be independently replaced. This segmentation allows specific worn parts to be replaced without replacing the entire coupler, maintaining strength while enabling repairability.
Solution Approach 2:
The design allows individual components such as the dampener and drive shaft to be discarded and replaced independently when worn, while the main housing and other durable components are retained and reused, reducing overall replacement costs while maintaining coupler integrity.
2Object-generated harmful factors
If rubber dampening material is used, then vibration dampening is improved, but reliability deteriorates due to premature failure
Solution Approach 1:
The dampening material parameters are changed from rubber to polyurethane, which offers superior durability and resistance to premature failure while maintaining effective vibration dampening capabilities throughout the service life of the coupler.
Solution Approach 2:
The coupler employs polyurethane composite material for the dampener assembly, combining the benefits of vibration absorption with enhanced structural integrity and longevity, eliminating the premature failure issues associated with rubber materials.
3Power
If coupler is designed for high torque (1,200 ft-lbs), then power transmission capability is improved, but complexity of monitoring dampening integrity increases
Solution Approach 1:
The coupler incorporates a visual inspection feature where the integrity of the dampening material can be assessed through color changes or visual indicators, allowing users to monitor the condition of the high-performance polyurethane dampener without complex electronic monitoring systems.
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
Enables cost-effective rebuildability and extended durability, ensuring reliable propulsion with visual maintenance cues, reducing replacement costs and downtime.
Implementation Method 1
the invention uses polyurethane dampening material which is widely used in industrial and automotive dampening applications
Implementation Method 2
The torque load from the engine slightly deforms the polyurethane dampers 20 and provides the dampening effect for the coupler
Implementation Method 3
The center shaft 18 and dampener hub 24 assembly rides on two shaft bushings 32, 34 that are pressed into the backing plate 14 and billet aluminum housing 12 respectively
Implementation Method 4
The fingers 28 extend slightly beyond the perimeter of the upstanding legs 26 so that they are positioned between the housing 12 and the dampener hub 24 so that they are the sole interface that transfers the torque from the engine to the sterndrive
Data Source
AI summary
A marine engine coupler for connecting a sterndrive input shaft to an engine flywheel. A splined central shaft connects the sterndrive input shaft to the coupling. Polyurethane dampers interface between the engine to the sterndrive to reduce vibration. There is a visual indicator on the coupler to allow the user to assess the integrity of the dampening material and give the user an indication that the dampening materials needs to be replaced.