Ship Propulsion Device with Counter Rotation and Coupling Unit
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Solution Overview
Problem
Conventional ship propulsion devices with single propellers suffer from energy loss and are difficult to manufacture and maintain, while counter rotating propeller systems require complex counter rotation units and high technical standards, necessitating a simpler and more reliable power transmission system.
Innovation Solution
A propulsion device featuring a rotational shaft with a rear propeller and a front propeller, a counter rotation unit with gears for reversing rotation, a coupling unit to disconnect power transmission, and a rotation preventing unit to stop the front propeller in case of breakdown, allowing for easy manufacturing, installation, and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a counter rotating propeller type propulsion device is used to acquire propulsive force from rotational energy of water streams, then propulsion performance is improved, but device complexity and manufacturing difficulty increase due to the counter rotation unit
Solution Approach 1:
The counter rotation unit is segmented into modular components: a counter rotation mechanism with bevel gears for reversing rotation direction, a coupling unit with friction members for selective engagement/disengagement, and a rotation preventing unit with brakes. This modular segmentation reduces manufacturing complexity while maintaining the ability to recover rotational energy from water streams.
Solution Approach 2:
A coupling unit with friction members acts as an intermediary between the rotational shaft and the counter rotation unit. This intermediary allows controlled power transmission and easy disengagement, simplifying the overall system by providing a straightforward mechanism to connect or disconnect the counter rotation unit without complex mechanical linkages.
2Stability of the object's composition
If a counter rotation unit with hollow shaft is used to reverse rotation of propellers, then counter rotation is achieved, but ease of manufacture and installation deteriorates
Solution Approach 1:
The counter rotation unit is divided into separate components: a counter rotation mechanism with bevel gears mounted on a solid shaft, a coupling unit, and a rotation preventing unit. This segmentation eliminates the need for complex hollow shaft structures while maintaining stable counter rotation through the gear mechanism.
Solution Approach 2:
The counter rotation function is extracted from the shaft structure and implemented through a separate bevel gear mechanism. This extraction simplifies manufacturing by using standard gear components rather than requiring precision-machined hollow shafts with internal rotation mechanisms.
3Reliability
If a separate unit for emergency operation is added to operate ship with remaining propeller during breakdown, then reliability is improved, but device complexity increases
Solution Approach 1:
The coupling unit serves multiple functions: it transmits power during normal operation, enables emergency operation by disconnecting the counter rotation unit when friction members slip, and prevents rotation of the front propeller through the rotation preventing unit. This multi-functionality eliminates the need for separate emergency operation mechanisms.
Solution Approach 2:
The friction members in the coupling unit automatically slip when excessive torque is applied during counter rotation, automatically disengaging the counter rotation unit and enabling emergency operation with the rear propeller alone. This self-service mechanism provides reliability without adding complex control 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
The solution enables stable counter rotation of propellers, simplifies the power transmission system, allows for automatic power cutoff, and prevents damage to the counter rotation unit during emergencies, facilitating easier maintenance and installation.
Implementation Method 1
The coupling unit may include a friction member disposed between the rotational shaft and the counter rotation unit to prevent slippage.
Data Source
AI summary
Disclosed are a propulsion device for a ship and a ship having the same. The propulsion device may include a rotational shaft, a rear propeller fixed to the rotational shaft, a front propeller rotatably supported by the drive shaft in front of the rear propeller, a counter rotation unit disposed in an installation space of a stern of a ship body and including a plurality of gears configured to reverse rotation of the rotational shaft and transmit the reversed rotation to the front propeller and a gear box configured to receive the plurality of gears, a coupling unit configured to separably connect the rotational shaft with the counter rotation unit and cut off power transmission from the rotational shaft to the counter rotation unit upon disconnection therebetween, and a rotation preventing unit configured to prevent rotation of the front propeller when the coupling unit is separated.