Marine Drive Isolating Joint for Motor Noise and Vibration
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Solution Overview
Problem
Existing marine propulsion systems with electric motors generate prominent tonal noise and vibrations that travel through structures with minimal resistance, leading to poor sound quality and potential annoyance.
Innovation Solution
Incorporation of vibration isolating joints with elastomeric members and compression limiters to clamp the motor housing and supporting frame, limiting vibration transfer and preventing over-clamping during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid structural connections are used between motor housing and supporting frame, then structural strength and stability are improved, but noise and vibration transmission increase
Solution Approach 1:
The patent introduces elastomeric isolators as intermediary elements between the motor housing and supporting frame. These isolators serve as mediators that mechanically connect the two structures while simultaneously damping vibrations and reducing noise transmission through their elastic properties and inherent damping characteristics.
Solution Approach 2:
The patent employs composite material construction by combining rigid structural components (metal housing and frame) with flexible elastomeric materials. This composite approach allows the rigid parts to provide structural strength while the elastomeric isolators provide vibration isolation, achieving both strength and noise reduction simultaneously.
2Object-generated harmful factors
If elastomeric isolators are used to reduce vibration transfer, then noise transmission is reduced, but connection strength and rigidity decrease
Solution Approach 1:
The patent optimizes the elastomeric isolators by adjusting their physical parameters including durometer hardness, dimensions, and mounting configuration. These parameter changes allow the isolators to provide adequate vibration isolation while maintaining sufficient connection strength to support the motor housing and withstand operational loads.
Solution Approach 2:
The hybrid connection system combines the strength of rigid metal mounting brackets with the vibration-damping properties of elastomeric materials. This composite connection approach ensures that the overall assembly maintains structural integrity while effectively reducing noise transmission through the elastomeric components.
3Object-generated harmful factors
If multiple isolating joints are added to reduce vibrations, then noise isolation is improved, but device complexity increases
Solution Approach 1:
The patent applies vibration isolation at critical locations where vibration generation and transmission are most significant, rather than uniformly throughout the entire structure. By strategically placing elastomeric isolators at key mounting points between the motor housing and supporting frame, effective vibration isolation is achieved with a limited number of components.
Solution Approach 2:
The patent divides the marine drive system into distinct modular segments (motor housing, gearcase, supporting frame) and applies isolation joints at the interfaces between these segments. This segmentation approach allows vibration isolation to be implemented in a systematic and manageable way, reducing overall system complexity while maintaining effectiveness.
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
Reduces noise transmission and enhances sound quality by isolating vibrations, minimizing aquatic noise disturbance.
Implementation Method 1
an elastomeric member which is clamped between the extension leg and the supporting frame and configured to limit transfer of vibrations from the extension leg to the supporting frame
Implementation Method 2
configured to limit transfer of vibrations from the extension leg to the supporting frame
Data Source
AI summary
A marine drive is for propelling a marine vessel in a body of water. The marine drive has a motor housing, the motor housing having a first housing portion and a second housing portion which together define a motor cavity; an electric motor nested in the first housing portion, the electric motor being configured to cause rotation of an output shaft axially extending from the first housing portion; a propulsor coupled to the output shaft so that rotation of the output shaft causes rotation of the propulsor; and an elastomeric isolator located radially between the electric motor and the first housing portion. The elastomeric isolator is configured to isolate vibrations emanating from the electric motor and limit transfer of said vibrations to the first housing portion.