Watercraft Propulsion Mounting Structure for Propulsor Vibration Control
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Solution Overview
Problem
Existing propulsion devices for water-surface movable bodies using electric motors face significant vibrations due to the propulsor, despite reduced vibrations from the electric motor itself, necessitating a solution to effectively reduce these vibrations.
Innovation Solution
A mounting structure for the propulsion device that includes a fixed member attached to the hull, a support member, and a plurality of mounting members arranged on opposite sides of a virtual line passing through the electric motor's center, with specific positioning and spring constants to stabilize the case, reducing vibrations by aligning the elastic center with the device's center of gravity and using a support member to sandwich the case from above and below.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electric motor is used as driving source, then CO2 emissions are reduced and energy efficiency is improved, but vibrations from propulsor become more noticeable
Solution Approach 1:
The mounting members act as intermediary elements between the propulsion device and the support member. These mounting members include vibration reduction mechanisms that absorb and dampen vibrations from the propulsor before they are transmitted to the hull, thus mediating the harmful vibration effect while maintaining the energy efficiency benefits of the electric motor
Solution Approach 2:
The vibration reduction mechanism converts the harmful vibrations from the propulsor into beneficial damping effects. By using elastic elements and vibration isolation structures, the system transforms the vibrational energy into heat through internal friction, thereby reducing the transmission of harmful vibrations to the hull while maintaining propulsive effectiveness
2Stability of the object's composition
If mounting members are arranged on opposite side of hull with virtual line interposed, then support stability is improved, but device complexity increases
Solution Approach 1:
The mounting structure is segmented into multiple independent mounting members arranged on opposite sides of the virtual line. Each mounting member can be independently designed and positioned, allowing for optimized vibration reduction while maintaining overall structural stability. This segmentation enables modular assembly and simplifies manufacturing despite the distributed configuration
Solution Approach 2:
The mounting members are positioned asymmetrically relative to the virtual line passing through the electric motor center, with specific arrangements that create balanced support forces. This asymmetric positioning optimizes the distribution of vibrational forces and improves stability without requiring symmetric complexity in all directions
Data Source
AI summary
A mounting structure of a propulsion device for a water-surface movable body. The propulsion device includes a case, an electric motor accommodated in the case, and a propulsor supported by the case and configured to rotate by a driving force of the electric motor. The mounting structure includes a fixed member fixed to a hull of the water-surface movable body, a support member attached to the fixed member via an attachment shaft and supporting the case, and a plurality of mounting members arranged between the support member and the case. In a plan view or a bottom view, the plurality of mounting members is arranged on an opposite side of the hull with a virtual line interposed therebetween, the virtual line passing through a center of an output shaft of the electric motor and being parallel to the attachment shaft.