Water-Surface Propulsion Device With Split Bearings for Ring-Gear Loads
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Solution Overview
Problem
Existing propulsion devices for water-surface movable bodies face challenges in withstanding the reaction force of ring gears while maintaining compact size and improving energy efficiency, as large bearings are required to handle the torque, leading to increased device size.
Innovation Solution
A propulsion device design featuring a planetary deceleration mechanism and steering deceleration mechanism with bearings arranged to distribute the reaction force of the ring gear, utilizing a turning portion with an enlarged diameter and refrigerant supply mechanism positioned below the enlarged diameter to reduce bearing size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bearings are enlarged to increase their strength, then the propulsion device becomes large
Solution Approach 1:
The bearing support structure is segmented into upper and lower bearings arranged vertically at different radial positions. This segmentation allows each bearing to handle a portion of the reaction force, enabling the use of smaller individual bearings while collectively withstanding the total load from the ring gear.
Solution Approach 2:
The bearing arrangement transitions from a single-plane configuration to a multi-dimensional configuration by positioning bearings both axially (upper and lower) and radially (different distances from turning axis). This dimensional change distributes the reaction force across multiple spatial locations, reducing the size requirement for each bearing.
2Volume of moving object
If bearings are made compact, then the propulsion device becomes compact, but the reaction force of the ring gear cannot be sufficiently withstood
Solution Approach 1:
Multiple compact bearings (upper and lower) are merged in their load-bearing function to collectively withstand the reaction force. While each individual bearing remains compact, their combined support structure achieves the necessary total load capacity to handle the ring gear reaction force.
3Strength
If large bearings are used to withstand the reaction force, then the load is sufficient, but the propulsion device weight increases
Solution Approach 1:
The weight burden is segmented across multiple smaller bearings rather than concentrated in one large bearing. This segmentation maintains the total load capacity while reducing the overall weight, as multiple compact bearings weigh less than a single large bearing providing equivalent support.
Data Source
AI summary
A propulsion device for a water-surface movable body includes an upper case, a propulsion motor accommodated in the upper case, a lower case supported by the upper case, a propulsor supported by the lower case, a planetary deceleration mechanism configured to decelerate rotation of the propulsion motor, a steering motor accommodated in the upper case, and a steering deceleration mechanism configured to decelerate rotation of the steering motor. The lower case includes a turning portion having a cylindrical shape, the planetary deceleration mechanism is arranged on an inner circumference of the turning portion, the lower case is supported by the upper case via an upper bearing and a lower bearing, and the steering deceleration mechanism includes a ring gear arranged between the upper bearing and the lower bearing and coupled to an outer circumferential surface of the turning portion.