Patent Description:
Propulsion oriented devices, also known under the acronym "POD", are used for propulsion of ships, vessels or the like. A propulsion oriented device generally includes a gondola attached to a part of the vessel, for instance to the hull of the vessel. The gondola is mechanically linked to the vessel in such a way that it may pivot about an axis, generally substantially vertical.

The gondola accommodates a propulsion shaft which supports, for example, a propeller. The rotation of the propulsion shaft makes the propeller rotate and causes propulsion of the vessel.

In order to ensure the rotation of the propulsion shaft, some propulsion oriented devices include an electric motor accommodated inside the gondola. For instance, the electric motor may include a stator attached to the gondola and a rotor attached to the propulsion shaft.

Document <CIT> discloses a propulsion oriented device with an electric motor inside the gondola and an arrangement to cool it down which comprises a cooling rotating interface.

A drawback of such an arrangement is that the electric motor may generate an important amount of heat. To remedy to this drawback, it has been proposed a cooling system including an airflow generator mounted on the vessel, a cooler able to cool an airflow generated by the airflow generator, a duct to convey the cold airflow from the cooler to the electric motor and a duct to convey a warm airflow from the electric motor to the cooler. Since the airflows need to have a portion within the ship and a portion within the gondola, a cooling rotating interface is foreseen to pass the airflows over the boundary between the vessel to the gondola. To do so, a cooling rotating interface generally includes, in the referential of the vessel, a static air box and a rotating air diffuser. A dynamic sealing is implemented between the air box and the air diffuser, which isolates the cold and warm airflows from each other.

Although such cooling systems are generally considered satisfactory, it appears sometimes that the pressure drop inside the ducts of the cooling system depend on the steering angular position. As a result, the cooling performance of the electric motor depends on the steering angle of the propulsion oriented device. For a vessel equipped with more than one propulsion oriented device, angular orientation of some of the propulsion oriented devices may lead to performance power imbalance and/or derating.

The invention aims at overcoming the above-mentioned drawbacks.

More specifically, the invention aims at providing a cooling rotating interface which allows obtaining flow rates for the warm and cold fluid flows which do not depend on a steering angular position of a propulsion oriented device.

According to the invention, it is proposed a cooling rotating interface according to the features of current claim <NUM>.

In an embodiment, the inner cylinder has a circular axial cross section, the air box having a circular axial cross section, the axial cross section of the air box having a diameter equal to a diameter of the axial cross section of the inner cylinder multiplied by a factor within a range <NUM>,<NUM> to <NUM>,<NUM>.

Such an arrangement allows having an area for the cold air flow substantially equal to the area for the warm air flow, taking into account the presence of elements typically present in a cooling rotating interface of propulsion oriented devices, such as traverses or gratings, which obstruct partially the fluid flow inside the inner cylinder.

According to the invention, the main portion includes a truncated cone having a first smaller diameter circular end and a second larger diameter circular end, the first circular end being intended to be closer to the vessel than the second circular end.

Such an arrangement allows having a transition between a cooling rotating interface and an internal volume of the propulsion oriented device, in a particularly adapted manner for a part manufactured by boilermaking.

In an advantageous manner, the truncated cone includes an inner protrusion extending radially inwards from the second circular end.

The inner protrusion allows supporting a ring for sealing the first and second fluid paths from each other.

One may also foresee a peripheral portion radially surrounding the main portion and including an outer cylinder of revolution intended to be located radially outwards the air box, with reference to the axis of rotation.

Having a peripheral portion including a cylinder of revolution allows keeping the same area for the warm air flow substantially equal to the area for the cold air flow despise increase of the latter in the truncated cone, while reducing the volume of a closed space intended to contain oil for lubricating a steering assembly. In case the central channel is used for the warm air flow, the same advantages may be obtained.

Preferably, the outer cylinder has a circular axial cross-section, a diameter of the outer cylinder being equal to a diameter of the axial cross-section of the second circular end multiplied by a factor within a range <NUM>,<NUM> to <NUM>,<NUM>.

Such an arrangement allows increasing the diameter at the same level as the truncated cone while avoiding perturbation of the fluid flow due to excessive speed variations of the fluid on a short distance.

One may also foresee a plurality of radially extending joining parts attaching the peripheral portion to the main portion.

In an embodiment, the joining parts have a thickness along the tangential direction within a range <NUM> to <NUM>.

Preferably, the joining parts have a thickness along the tangential direction within a range <NUM> to <NUM>.

In another embodiment, the joining parts are regularly spread over the circumference of the main portion so that the angle between two adjacent joining parts taken among the plurality of joining parts is within <NUM>° and <NUM>°.

Such a plurality of joining parts allows attaching the main and peripheral portions to each other without excessively perturbating the fluid flow between the air diffuser and the air box.

In an embodiment, the peripheral portion includes a crown protruding radially outwards from the outer cylinder.

This crown allows attaching the air diffuser to an end cover attached to a slewing bearing or a steering arrangement of the propulsion oriented device.

One may also foresee at least one static seal ring chosen among a first static seal ring in axial contact with the crown and a second static seal ring in radial contact with the outer cylinder.

This static seal ring allows implementing a sealing at a contact location between the peripheral portion and the end cover, inter alia so as to seal the closed space intended to contain oil for lubricating the steering assembly.

In another embodiment, the peripheral portion includes a first collar extending radially inwards from a first end of the outer cylinder, the first end being intended to be proximate to the vessel, the peripheral portion including a cylindrical protrusion extending axially from an inner edge of the first collar and on a side of the first collar opposite to the side in which the outer cylinder is located.

The cylindrical protrusion allows supporting a dynamic seal ring between the peripheral portion and the steering top cover, inter alia so as to seal the closed space intended to contain oil for lubricating the steering assembly.

According to the invention, it is proposed a cooling rotating interface for a propulsion oriented device pivotable relative to a vessel around an axis of rotation, the cooling rotating interface including an air box intended to be attached to the vessel, a first fluid path for a cold fluid flow, a second fluid path for a warm fluid flow, and an air diffuser as defined above, wherein the air diffuser delimits the first and second fluid paths from each other.

Preferably, the air box includes a part of revolution coaxial to the main portion, the cooling rotating interface including a labyrinth seal located axially between the air diffuser and the part of revolution.

This labyrinth seal allows implementing a dynamic seal so as to isolate the airflows from each other.

The present invention and its advantages will be better understood by studying the detailed description of a specific embodiment given by way of nonlimiting examples and illustrated by the appended drawings on which:.

With reference to <FIG>, it is schematically depicted a cooling rotating interface <NUM>. The cooling rotating interface <NUM> is intended to be installed between a propulsion oriented device (not shown) and a part of a vessel, for instance the hull of the vessel (not shown). The vessel is located above the cooling rotating interface <NUM> whereas the propulsion oriented device is located below the cooling rotating interface <NUM>. The propulsion oriented device is pivotable relative to the vessel around an axis of rotation <NUM>.

The cooling rotating interface <NUM> is intended to lead a cold airflow from a cooler located inside the vessel into an electric motor located inside the propulsion oriented device, and to lead a warm airflow from the electric motor into the cooler. To that end, the cooling rotating interface <NUM> includes an air box <NUM> and an air diffuser <NUM>. The air box <NUM> is attached to the vessel whereas the air diffuser <NUM> is attached to the propulsion oriented device. Hence, the air diffuser <NUM> is able to rotate, with respect to the air box <NUM>, about the axis of rotation <NUM>.

It is defined an orthonormal direct vector basis <NUM> attached to the air box <NUM>. The basis <NUM> consist of a vector X, a vector Y and a vector Z. The vector Z is parallel to the axis of rotation <NUM>.

In the present application, the terms "axial", "radial", "tangential" and variations thereof will be understood as referring to the axis of rotation <NUM>. The words "cylinder" and "cylindrical" will be understood according to their common definition, being namely that a cylindrical surface is a surface consisting of all the points on all the lines which are parallel to a given line and which pass through a fixed plane curve in a plane not parallel to the given line. The words "up", "low", "down" and variations thereof will be understood as referring to the basis <NUM> when the cooling rotating interface <NUM> is normally installed on a vessel, that is assuming that the vector Z is substantially vertically upwardly directed.

Referring to <FIG>, the air box <NUM> includes an upper, flat plate <NUM> perpendicular to the vector Z.

The air box <NUM> further includes an upper cylinder of revolution <NUM> and a lower cylinder of revolution <NUM>. The cylinders <NUM> and <NUM> have a circular axial cross-section around the axis <NUM> and with respective diameters d<NUM>, d<NUM>. The diameter d<NUM> is strictly greater than the diameter d<NUM>. More specifically, the diameter d<NUM> is within a range <NUM> to <NUM> and the diameter d<NUM> is within a range <NUM> to <NUM>. A lower end of the cylinder <NUM> is linked to an upper end of the cylinder <NUM> by a flat, frontal surface <NUM> perpendicular to the vector Z. The upper plate <NUM> is linked to an upper end of the cylinder <NUM>.

On the lower end of the cylinder <NUM>, the air box <NUM> includes a collar <NUM>. The collar <NUM> extends radially outwards from the lower end of the cylinder <NUM>.

The air box <NUM> includes a plurality of, e.g. eleven (<NUM>) reinforcing ribs <NUM>. The reinforcing ribs <NUM> are intended to strengthen the fixation of the collar <NUM> to the cylinder <NUM>. The air box <NUM> further includes a plurality of, e.g. four (<NUM>) reinforcing ribs <NUM>. The reinforcing ribs <NUM> extend radially outwards from the cylinder <NUM>. The reinforcing ribs <NUM> extend axially between the upper plate <NUM> and the frontal surface <NUM>.

The air box <NUM> includes a rectangular hatch <NUM> arranged on the cylinder <NUM>. The hatch <NUM> is intended to allow a technician to access, from the vessel, to the inner volume of the propulsion oriented device.

The air box <NUM> further includes a hatch <NUM> arranged on the cylinder <NUM>, proximate to the collar <NUM>. The hatch <NUM> intends to allow implementing a maintenance of a seal ring installed proximate to the collar <NUM>, such as an air diffuser - steering top cover oil dynamic seal.

The air box <NUM> further includes an upper duct <NUM> with an upper port <NUM>, and a lower duct <NUM> with a lower port <NUM>. The ducts <NUM> and <NUM> are intended to be fluidly connected, via the respective ports <NUM> and <NUM>, with flexible tubes of a cooling system of the propulsion oriented device. More specifically, the upper duct <NUM> is intended to be connected to a flexible tube fluidly connected to an outlet of a cooler (not depicted) of the cooling system, whereas the lower duct <NUM> is intended to be fluidly connected to a flexible tube fluidly connected to the inlet of the cooler. An airflow generator, such as a fan (not depicted), is mounted on one of these flexible tubes.

Hence, through the air box <NUM>, a cold airflow coming from the cooler passes through the upper duct <NUM> whereas a warm airflow, directed towards the cooler, passes through the lower duct <NUM>.

Without departing from the scope of the invention, one may connect the upper duct <NUM> to the inlet of the cooler and connect the lower duct <NUM> with the outlet of the cooler. In such case, the cold air flow passes through the lower duct <NUM> whereas the warm air flow passes through the upper duct <NUM>.

Referring now to <FIG>, the air diffuser <NUM> includes a main portion <NUM> and a peripheral portion <NUM>. The peripheral portion <NUM> radially surrounds the main portion <NUM>. More specifically, the radial location of the peripheral portion <NUM> is outwards from the radial location of the cylinder <NUM> of the air box <NUM>, and the axial location of the peripheral portion <NUM> is right below the cylinder <NUM>. The main portion <NUM> is located radially inside the cylinder <NUM>. The main portion <NUM> includes a top end <NUM> axially located right below the cylinder <NUM>. The cylinder <NUM> includes a seal <NUM> and/or a labyrinth seal (not depicted) implementing a dynamic sealing between the cylinder <NUM> and the top end <NUM>.

The main portion <NUM> includes an upper cylinder of revolution <NUM> and a lower truncated cone <NUM>. The axis of revolution of the cylinder <NUM> and the axis of revolution of the truncated cone <NUM> are the same as the axis of rotation <NUM>. The angle α of the truncated cone <NUM> with reference to the direction of the vector Z is within <NUM>° and <NUM>°.

The axial cross-section of the cylinder <NUM> is circular around the axis of rotation <NUM> and has a diameter d<NUM> equal to the diameter d<NUM>. The truncated cone <NUM> includes an upper end <NUM> and a lower end <NUM>. The truncated cone <NUM> is joined to the cylinder <NUM> by its upper end <NUM>. The ends <NUM> and <NUM> are two circles around the axis of rotation <NUM>, having respective diameters d<NUM> and d<NUM>. The diameter d<NUM> equals the diameter d<NUM>. The diameter d<NUM> is strictly larger than the diameter d<NUM>. In the depicted embodiments, the diameter d<NUM> is within a range <NUM> to <NUM>.

Hence, the main portion <NUM> is a solid of revolution around the axis of rotation <NUM>. The main portion <NUM> delimits a first fluid path, being inside the cylinder <NUM> and the cone <NUM>, for the cold airflow delivered by the upper duct <NUM>, from a second fluid path, being between the cylinder <NUM> and the cylinder <NUM>, for the warm fluid flow collected by the lower duct <NUM>.

The main portion <NUM> includes a radial protrusion <NUM> extending radially inwards from the truncated cone <NUM>, at its lower end <NUM>. The main portion includes a plurality of, e.g. ten (<NUM>) reinforcing ribs <NUM> which strengthen the fixation of the protrusion <NUM> to the truncated cone <NUM>. The protrusion <NUM> intends to allow the fixation of a static seal ring (not depicted) located inside the inner volume of the propulsion oriented device.

The peripheral portion <NUM> includes a cylinder of revolution <NUM>. The cylinder <NUM> has a circular axial cross-section around the axis of rotation <NUM> with a diameter d<NUM> within a range <NUM><NUM> to <NUM><NUM>. The cylinder <NUM> includes a lower end <NUM> and an upper end <NUM>. The peripheral portion <NUM> includes a lower collar <NUM> extending radially inwards from the cylinder <NUM>, at its lower end <NUM>.

The peripheral portion <NUM> includes a crown <NUM> extending radially outwards from the cylinder <NUM>. The crown <NUM> includes a plurality of through bores <NUM> intended to allow the fixation of the air diffuser <NUM> to a part, e.g. a steering end cover of the propulsion oriented device.

With reference to <FIG>, it is depicted a seal arrangement <NUM> between the peripheral portion <NUM> and an end cover <NUM> of the propulsion oriented device. The end cover <NUM> may be attached to a mobile part of a steering arrangement of the propulsion oriented device. The seal arrangement <NUM> includes a static seal ring <NUM> received in a groove <NUM> of the end cover <NUM>, and a static seal ring <NUM> received in a groove <NUM> of the cylinder <NUM>. The seal ring <NUM> is in static axial contact with the crown <NUM> whereas the seal ring <NUM> is in static radial contact with a cylindrical surface of the end cover <NUM>. A plurality of screws <NUM> attach the end cover <NUM> and the crown <NUM> to each other.

The peripheral portion <NUM> includes an upper collar <NUM> extending radially inwards from the cylinder <NUM> at its upper end <NUM>. The upper collar <NUM> includes a radial inner edge <NUM> having the shape of a circle around the axis of rotation <NUM> and with a diameter d<NUM>. In the depicted embodiment, the diameter d<NUM> is within a range <NUM> to <NUM>.

The peripheral portion <NUM> includes a cylindrical protrusion <NUM> extending axially upwards from the edge <NUM>.

Hence, the collar <NUM>, the collar <NUM> and the cylindrical protrusion <NUM> allow the fixation of a dynamic seal arrangement between a steering top cover and the air diffuser <NUM>.

The air diffuser <NUM> further includes a plurality of, e.g. ten (<NUM>) attaching ribs <NUM>. The attaching ribs <NUM> extend radially outwards from the lower end of the cylinder <NUM> and from the truncated cone <NUM>. The attaching ribs <NUM> extend radially inwards from the cylinder <NUM> and axially downwards from the upper collar <NUM>. Hence, the attaching ribs <NUM> allow attaching the main portion <NUM> and the peripheral portion <NUM>.

The attaching ribs <NUM> are regularly spread over the circumference of the truncated cone <NUM>. Hence, the angle β between two adjacent ribs <NUM> is within a range to <NUM>° to <NUM>°. In the depicted embodiment, the angle between two adjacent ribs <NUM> is <NUM>°.

In the depicted embodiment, the ribs <NUM> have a thickness within a range <NUM> to <NUM>, and more specifically a thickness being equal to <NUM>.

Referring now to <FIG>, a dynamic seal arrangement <NUM> is depicted between a steering top cover <NUM> and the air diffuser <NUM>. Namely, the top cover <NUM> may be attached to a static part of the steering arrangement and the air box <NUM> may be attached to the top cover <NUM>. The seal arrangement <NUM> may include a first lip seal <NUM> and a second lip seal <NUM> attached to the cylindrical protrusion <NUM>. Using two lip seals for implementing dynamic sealing between the cylindrical protrusion <NUM> and the top cover <NUM> allows improving the sealing effect relative to the air flow passing through the cooling rotating interface, and relative to oil lubricating inside the steering arrangement.

Claim 1:
Cooling rotating interface (<NUM>) for a propulsion oriented device pivotable relative to a vessel around an axis of rotation (<NUM>), the cooling rotating interface (<NUM>) including an air box (<NUM>) intended to be attached to the vessel, and an air diffuser (<NUM>) intended to be attached to the propulsion oriented device, and including a main portion (<NUM>) being a solid of revolution around the axis of rotation (<NUM>) characterized in that the air box (<NUM>) comprises :
- an upper cylinder of revolution (<NUM>) and a lower cylinder of revolution (<NUM>), each having a circular axial cross-section around the axis of rotation (<NUM>), the diameter (d16) of the lower cylinder of revolution (<NUM>) being strictly greater than the diameter (d14) of the upper cylinder of revolution (<NUM>), and
- an upper duct (<NUM>) and a lower duct (<NUM>), in that the air diffuser (<NUM>) comprises :
- a peripheral portion (<NUM>) surrounding the main portion (<NUM>) and radially located outwards from the lower cylinder (<NUM>) and axially located right below said lower cylinder (<NUM>), the main portion (<NUM>) being located radially inside the lower cylinder (<NUM>), and comprising an inner cylinder of revolution (<NUM>) circular around the axis of rotation (<NUM>) and having a diameter (d42) equal to the diameter of the upper cylinder of revolution (<NUM>) and a truncated cone (<NUM>) having a first circular end (<NUM>) and a second circular end (<NUM>), the second circular end (<NUM>) having a larger diameter than the first circular end (<NUM>), the first circular end (<NUM>) being preferably intended to be closer to the vessel than the second circular end (<NUM>), and in that the main portion (<NUM>) delimits a first fluid path inside the inner cylinder of revolution (<NUM>) and the truncated cone (<NUM>) through the upper cylinder (<NUM>) and the upper duct (<NUM>) and a second fluid path, between the inner cylinder of revolution (<NUM>) and the lower cylinder of revolution (<NUM>) through the lower duct (<NUM>).