Ship's steering unit whose angular position is servo-controlled by an electric motor

Abstract

The ship's steering unit comprises a mounting which is part of the structure of the ship, and in which a rudder is pivotally mounted, the angular positioning of said rudder being servo-controlled by a motor. The motor is an electric motor comprising a stator rigidly fixed to said mounting, and a rotor rigidly fixed to said rudder. The steering motor is powered at variable frequency and at variable voltage, and it transmits the torque necessary for servo-controlling the rudder electromagnetically, i.e. without physical contact, thereby eliminating problems of wear. In addition, the steering unit is simplified by reducing the number of items of equipment making up said unit, thereby making it easier to install on board and contributing to making it more reliable.

Description

[0001] The invention relates to a ship's steering unit comprising a mounting which is part of the structure of the ship, and in which a rudder is pivotally mounted, the angular positioning of said rudder being servo-controlled by a motor. The invention applies more particularly to a large ship such as a cruise liner in which the servo-controlling of the position of the rudder is assisted by machinery.[0002] Conventionally, the rudder is constrained to move with at least two hydraulic motors that are fed with oil under pressure by a hydraulic power unit. The hydraulic power unit itself has two electric motors powered by an electricity network to provide redundancy in servo-controlling the rudder. More particularly, the top portion of the rudder, which is mounted to turn about a vertical axis, is provided with a toothed ring situated in a horizontal plane, and each hydraulic motor has an outlet gear meshed with said ring to transmit servo-control torque to the rudder. That solution ma...

AI Technical Summary

Benefits of technology

[0004] An object of the invention is to remedy those drawbacks by providing an electrically servo-controlled steering unit that is compact, and that requires only a minimal amount of maintenance.

[0005] To this end, the invention provides a ship's steering unit comprising a mounting which is part of the structure of the ship, and in which a rudder is pivotally mounted, the angular positioning of said rudder being servo-controlled by a motor, wherein said motor is an electric motor comprising a stator rigidly fixed to said mounting, and a rotor rigidly fixed to said rudder. This motor, which is a steering motor, transmits the torque necessary for servo-controlling the rudder electromagnetically, i.e. without physical contact, which eliminates problems of wear. A fixed position is thus held by means of a power supply adapted to the type of electric motor in use. In the case of a synchronous motor, blocking in position is performed by injecting direct current (DC) into the rotor / stator windings. In contrast, in the case of an asynchronous motor, blocking in position is performed by adjusting the power supply frequency to match the rotor slip frequency, i.e. by adjusting it to the same frequency, in such a manner as to zero the mechanical speed of the rotor. This configuration simplifies the steering unit by reducing the number of items of equipment that make up said unit, thereby making it easier to install on board and contributing to making it more reliable.

[0006] In a preferred embodiment of the invention, the rudder includes a steering cone pivotally mounted in said mounting, and the electric motor is mounted inside said steering cone. The steering unit of the invention is thus made even more compact. The rudder includes an underwater portion that may be in the form of a rudder blade, or else in the form of a pod enclosing a propulsion motor for propelling said ship. When it is in the form of an underwater pod enclosing a propulsion motor that is cooled by a ventilation system, the steering motor may be cooled by diverting some of the ventilation provided for the propulsion motor. It is thus not necessary to implement additional ventilation means dedicated specially to cooling the steering motor.

Problems solved by technology

That configuration suffers from the drawback of being less compact due to the need to have a larger number of motors equipped with gearboxes, and it requires regular maintenance of said gearboxes in order to keep them in satisfactory working order.

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