Ship Propulsion Unit Segmentation for Steering and Weight Balance
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Solution Overview
Problem
Conventional ship propulsion units face limitations in spacing and weight balance due to their configuration, which restricts the number of units that can be mounted and affects smooth maneuvering.
Innovation Solution
A ship propulsion unit design featuring a crankshaft extending in the front-rear direction, with a power transmission mechanism that includes a drive shaft and a rotation mechanism allowing the propeller shaft to rotate independently, reducing the distance between units and minimizing weight distribution disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the propulsion unit is configured to entirely swing around the axis of the steering shaft, then the steering operation is achieved, but the distance between adjacent propulsion units must be increased to prevent interference
Solution Approach 1:
The propulsion unit is divided into an upper case (containing the engine and upper power transmission mechanism) that remains fixed, and a lower case (containing the propeller shaft and lower power transmission mechanism) that rotates independently for steering. This segmentation allows the lower case to swing for steering while the upper case remains stationary, eliminating interference between adjacent units.
Solution Approach 2:
The lower case is designed to rotate dynamically relative to the upper case around the drive shaft extension axis, enabling the propeller shaft to change direction for steering operations while the engine and upper case remain fixed in position.
2Ease of operation
If the propulsion unit including a heavy-weight engine entirely swings during the steering operation, then the steering operation is achieved, but the weight balance of the ship is disturbed
Solution Approach 1:
The propulsion unit is segmented into a fixed upper case containing the heavy engine and a rotating lower case containing the propeller shaft. This allows only the lighter lower case to rotate during steering, while the heavy engine remains stationary, thereby minimizing disturbance to the ship's weight balance.
3Power
If the first transmission is disposed further rearward with the engine interposed therebetween, then the power transmission is achieved, but the center of gravity position shifts rearward
Solution Approach 1:
The power transmission mechanism is arranged in a vertical dimension with the drive shaft extending downward from the engine to the propeller shaft, rather than extending rearward horizontally. This vertical arrangement allows the engine to be positioned higher and forward, preventing rearward shift of the center of gravity while still achieving effective power transmission.
Data Source
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AI summary
A ship propulsion unit (10) includes: an engine (21) including a crankshaft (23) extending in a front-rear direction of a ship; a propeller shaft (51); a power transmission mechanism (60) configured to couple the crankshaft (23) and the propeller shaft (51); an upper case (30); and a lower case (40) accommodating the propeller shaft (51) and connected to the upper case (30). The power transmission mechanism (60) includes a drive shaft (65) extending from the upper case (30) toward the lower case (40). The upper case (30) and the engine (21) are fixed to a ship body (2). A connection portion between the upper case (30) and the lower case (40) is provided with a rotation mechanism (70) configured to rotate the lower case (40) around an axis of the drive shaft (65).