retractable thruster system

Abstract

A retractable propeller system for moving a propeller (1) on a vessel between an extended position in which the propeller extends below the bottom of the hull and at least one retracted position in which the propeller The propeller is located above the bottom of the hull, the system includes a tank (2) to which the propeller can be mounted, wherein the tank is configured to be in the bulkhead (3) of the ship's hull structure between an extended position and at least one retracted position movement, wherein a rack and pinion lifting system is configured to move the tank (3) in the enclosure (3) between an extended position and at least one retracted position, the lifting system comprising at least one rack (6) and pinion drive means (7) of at least one rack (6) fixedly connected to the vessel, the pinion drive comprising at least one pinion (8) configured to cooperate with the at least one rack (6), said pinion The transmission is connected to the tank (2).

Description

technical field [0001] The present invention relates to a retractable thruster system. Background technique [0002] Retractable thruster systems are widely used on ships, for example in propulsion systems and dynamic positioning systems, i.e. capable of keeping a ship above a given seafloor position and at a given position despite environmental forces acting on the ship. oriented system. These thrusters need to be retracted in certain situations to reduce the drag of the vessel, for example during high speed cruising or in shallow water, for example when entering a harbour. For care and maintenance reasons it is also possible to retract the propeller further and lift it into the hull or even onto the deck of the vessel. In addition, retractable thruster systems generally comprise a tank and a frame on which the thrusters are mounted, as disclosed eg in US 6,439,936 or WO2013 / 135858. The tank is vertically movable in the bulkhead of the vessel by an elevator mechanism con...

AI Technical Summary

Problems solved by technology

Such prior art retractable pusher systems have the problem that the securing system requires a large number of parts to perform the clamping of the tank in the enclosure, such as multiple pins, hydraulic motors and sometimes even very space consuming gearbox

Active control of the continuous powering and monitoring of the fixed system, for example of the actual position of the pin, thus becomes difficult, expensive and space consuming

Additionally, more active components increase the risk of system failure

Another problem with such existing systems is that the forces exerted by the pins or mandrels on the hull structure are static and do not account for hull deformations such as sag and mid-hog caused by waves and / or ship loads

Since this deformation can increase to about 5mm in the bulkhead of a tank for offshore dimensions, and since the pin is only statically loaded, this hull deformation can cause loss of contact

Another problem present in prior art retractable thruster systems is that if there is a very slight accidental displacement of the tank in the enclosure, relatively high forces may also be exerted on the lift mechanism, which may even be damaged

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