In-ship Retractable Thruster with Magnetic Detachment
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Solution Overview
Problem
Conventional thruster systems for drilling ships require complex and costly maintenance, especially in deep-water environments, as they need to be lifted and inspected, often necessitating heavy-duty lifting devices and underwater operations that are difficult and weather-dependent.
Innovation Solution
A retractable thruster apparatus with a locking device that allows the thruster to be easily detached and reattached above the water surface, using a power transmission shaft or wedge mechanism to secure the thruster in place, eliminating the need for heavy lifting devices and underwater operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the thruster is detached underwater by divers, then the thruster can be replaced outside the ship, but the operation becomes difficult and time-consuming due to complex wire handling and coupling metal fittings
Solution Approach 1:
The patent replaces the conventional mechanical detachment system (wires, coupling metal fittings) with a magnetic coupling system. The magnetic coupling allows the thruster to be held and detached through magnetic attraction and repulsion forces, eliminating the need for complex mechanical wire handling and coupling operations underwater. The magnetic coupling device includes a magnetic coupling member on the thruster and a corresponding magnetic coupling member on the ship, enabling simple attachment and detachment operations.
2Ease of repair
If heavy-duty lifting devices are used to lift the thruster above the water surface, then the thruster can be inspected and maintained on land, but the device complexity and cost increase significantly
Solution Approach 1:
The patent uses magnetic attraction forces to counteract the weight of the thruster during lifting operations. The magnetic coupling member on the ship generates sufficient magnetic attraction to hold and lift the thruster above the water surface without requiring heavy-duty mechanical lifting devices. This magnetic counterweight system replaces complex mechanical lifting equipment with a simpler magnetic field-based system.
3Ease of repair
If the thruster is detached underwater, then replacement is possible, but the operation is restricted by marine weather conditions
Solution Approach 1:
By replacing underwater mechanical detachment operations with magnetic coupling that can operate from above the water surface, the system eliminates weather-dependent underwater operations. The magnetic coupling allows thruster detachment and attachment to be performed in dry conditions on the ship deck, making operations independent of marine weather conditions.
4Weight of moving object
If the entire tubular body including the thruster is lifted up and lowered by rack & pinion or hydraulic cylinder systems, then the thruster can be positioned above the draft surface, but the weight to be lifted becomes extremely large requiring special heavy-weight lifting devices
Solution Approach 1:
The patent segments the lifting operation into two independent parts: (1) magnetic coupling for holding and lifting the thruster, and (2) simple wire-based lift-up device for final positioning. This segmentation allows the heavy lifting to be done by magnetic attraction, while only light positioning requires mechanical intervention, eliminating the need for complex rack & pinion or hydraulic cylinder systems that would need to handle the entire thruster weight.
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
Enables efficient and cost-effective inspection and maintenance of thrusters without the need for heavy lifting equipment, allowing for quick and weather-independent operations, reducing the complexity and cost of maintenance.
Implementation Method 1
a magnetic coupling member configured to attract or repel the magnetic coupling member of the thruster with a magnetic coupling force
Implementation Method 2
a magnetic coupling member configured to attract or repel the magnetic coupling member of the thruster with a magnetic coupling force
Implementation Method 3
each of the wedge seat and the engagement surface of the locking piece is formed to have an inclination angle equal to or smaller than a friction angle by which a wedge effect is maintained
Data Source
Figure 1
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AI summary
A thruster apparatus (1) includes: a thruster arrangement portion (10) provided at a hull and configured to open in an upper-lower direction; a storage seat (20) by which a thruster (3) projecting downward from a thruster arrangement portion (10) is stored in the thruster arrangement portion (10); an attachment seat (15) provided at a position, to which the storage seat (20) is fixed, of the hull; and fixing bolts that fix the storage seat (20) to the attachment seat (15). The thruster arrangement portion (10) is surrounded by wall surfaces (13) constituting a part of a hull structure. Locking devices (30) configured to hold the storage seat (20) at the attachment seat (15) when the fixing by the fixing bolts is released are provided at the wall surfaces (13). Locked states of the locking devices (30) can be activated or released from an upper portion of the thruster arrangement portion (10). With this, the thruster of a drilling ship or the like can be detached at a position above a draft surface in the ship by a simple handling device such that the thruster can be inspected or repaired at an offshore operating site.