Patent Description:
Watercrafts or boats are moved across water by a thrust force generated by a powering system or propulsion system. The powering system may include a motor, e.g. a diesel motor and/or an electric motor. Depending on the arrangement of the powering system, the powering system may be an inboard powering system, an outboard powering system or a sterndrive powering system.

Inboard powering systems include a motor situated and supported within the hull of the watercraft. Therefore, a significant space within the hull is required for arranging the motor, which limits the available space to be utilized for other purposes such as cabin space, storage, etc. In addition, as the motor is located inside the hull in a limited space, the accessibility of the motor for maintenance operations is hindered.

The motor of inboard powering systems generally drives a single propeller shaft having a first end coupled to the motor and a second end coupled to a propeller. The propeller shaft extends along the stern of the watercraft and rotates about the axis of the propeller shaft. The propeller shaft generally forms a fixed angle with the hull of the watercraft which cannot be adjusted or modified with respect to the water level. The position of the propeller is thus fixed relative to the watercraft, allowing incrustation of algae and mollusks onto the propeller shaft and the propeller. Therefore, no tilting operations, i.e. lifting the motor, are available. The hull comprises an aperture for passing the propeller shaft through the hull to connect the motor to the propeller. Although this aperture may be sealed, water and moisture may enter into the hull and may come into direct contact with the inboard powering system. This may result in corrosion and wear may increase. In addition, a precise alignment of the propeller shaft is required to prevent excessive vibrations and/or noise. Therefore, installation of inboard powering systems may involve a labor-intensive process.

Furthermore, inboard powering systems cannot rotate about a vertical direction to steer the watercraft. One or more rudders located behind the propeller are used for steering the watercraft which may adversely increase the draft of the watercraft.

In outboard powering systems, the motor is arranged outside the hull of the watercraft. Outboard powering systems typically include an upper structure supporting the motor, a vertical input shaft and a lower structure supporting a horizontal propeller shaft.

Outboard powering systems are typically attached to a transom of the watercraft. The entire outboard powering system can be rotated about the vertical axis to steer the watercraft. In addition, the entire outboard powering system can be pivoted about an axis extending parallel to the port - starboard direction of the watercraft so as to perform tilting operations, i.e. lifting the outboard powering system above the water level, and/or trimming operations, i.e. slightly adjust the thrust angle of the propeller shaft relative to the hull. Transoms may be subjected to wear which may increase the risk of detaching the outboard powering system from the transom. In addition, transoms may be subjected to high loads since the entire outboard powering system is moved for e.g. steering, tilting, and/or trimming. To withstand these high loads, structural reinforcements of the transom may be required. This may increase the size and/or weight of the transom which may limit the available space within the hull. As the whole outboard powering system can be moved, large actuators are usually required.

In addition, dimensions of the motor used in outboard powering systems is typically constrained by the forces required to move the outboard powering system with respect to the watercraft (e.g. tilting, trimming, and/or steering). Accordingly, employing larger motors is typically avoided.

Furthermore, the weight of outboard powering systems using an electric motor increases since the electric motor and the batteries are typically integrated within the outboard powering system. This generates higher loads when the powering system is moved relative to the watercraft. For this reason, powerful electric motors are not typically used in outboard powering systems.

Sterndrive powering systems include a motor arranged inside the hull of the watercraft and a drive system projecting from the hull coupled to the propeller.

Therefore, similarly to inboard powering systems, valuable space inside the hull is used, and accessibility to the motor for maintenance operations is hindered.

The drive system of a sterndrive powering system generally comprises a horizontal input shaft having a first end coupled to the motor and a second end coupled to a vertical intermediate shaft. This vertical intermediate shaft is connected to the propeller through a horizontal propeller shaft. The horizontal input shaft, the vertical intermediate shaft and the horizontal propeller shaft are typically enclosed and supported by a supporting structure extending outwardly from the hull of the watercraft.

In addition, the hull comprises an aperture for passing the horizontal input shaft through the hull to connect the motor with the vertical intermediate shaft. Although this aperture may be sealed, water and moisture may enter into the hull and may come into direct contact with the motor of the sterndrive powering system. This may result in corrosion and increased wear.

In some examples, the supporting structure extending outwardly from the hull may allow trimming operations, i.e. slightly adjust the thrust angle of the propeller shaft with the hull. However, steering movements (i.e. to navigate through a desired direction) and/or tilting movements (i.e. lifting the supporting structure above the water level), are generally restricted by the dimensions of the supporting structure. Only limited steering and/or trimming operations or movement can thus be performed. This may result in incrustation of algae and mollusks onto a portion of the supporting structure below a water level. Wear of the components below the water lever may consequently be increased.

As explained before, motors can be electric motors. Electric motors typically rotate at an electric motor revolutions per minute which is typically higher than the propeller revolutions per minute. Reductors may thus be used to adapt the electric motor revolutions per minute to the propeller revolutions per minute. These reductors may require a large space. Integrating an electric motor in any of the above-mentioned powering systems may thus be challenging.

<CIT> shows a powering system for a watercraft according to the preamble of claim <NUM>.

Examples of the present disclosure seek to at least partially reduce one or more of the aforementioned problems.

In a first aspect, a powering system for a watercraft is provided. The powering system for a watercraft comprises a propeller, an electric motor, and a gearbox coupled to the electric motor. The powering system for a watercraft further comprises an input shaft, an intermediate shaft, and a propeller shaft.

The input shaft has a first end coupled to the gearbox and a second end rotatably coupled to the intermediate shaft. The input shaft extends from the first end to the second end in a first direction. The intermediate shaft has a first end rotatably coupled to the input shaft and a second end rotatably coupled to the propeller shaft. The intermediate shaft comprises an upper portion and a lower portion, the lower portion being rotatably coupled to the upper portion. The upper portion of the intermediate shaft extends in a second direction. The propeller shaft has a first end rotatably coupled to the intermediate shaft and a second end coupled to the propeller. The propeller shaft extends from the first end to the second end in a third direction. The first direction is perpendicular to the second direction and substantially parallel to the third direction.

Additionally, the powering system for a watercraft comprises an upper supporting and a lower supporting structure. The upper supporting structure supports the electric motor and the gearbox. The upper supporting structure is configured to be tiltable coupled to a watercraft. The lower supporting structure supports the propeller and the propeller shaft. The lower supporting structure is rotatably coupled to the upper supporting structure to rotate about the second direction.

In this aspect, a powering system with an electric motor for moving a watercraft across water by a thrust force is provided. A compact powering system with an electric motor is thus provided. Any suitable electric motor may be used in the powering system according to the present disclosure.

The entire powering system, i.e. from the electric motor to the propeller, is arranged outside the hull of the watercraft. Therefore, the powering system may save space inside the hull. Furthermore, problems related to water entering into the hull may be avoided.

In addition, the entire powering system may be manufactured independent from the watercraft. For example, the powering system may be manufactured in a factory and then installed to the watercraft at a boat dealer. Manufacturing and logistics may thus be improved. In addition, less labor-intensive processes are required for installing the powering system into watercraft at the boat dealer. Efficiency and versatility of mounting the powering system in the watercraft may consequently be increased. Furthermore, maintenance operations may be simplified. For example, the entire power system can be detached from the watercraft and maintenance operations can be more easily performed. Therefore, any portion of the powering system may be easily accessed. Cost and time for replacing a failed component may be reduced.

The electric motor drives the gearbox which is connected to the input shaft. The input shaft extends and is configured to rotate about the first direction. In use, the first direction is substantially horizontal and extends substantially parallel to a bow to stern direction. The rotation of the input shaft about the first direction drives the rotation of the intermediate shaft about the second direction. The input shaft and the intermediate shaft are substantially perpendicular. An input shaft gear may be arranged at the second end of the input shaft to mesh a first intermediate shaft gear arranged at the first end of the intermediate shaft. These gears may be bevel and/or helical gears to transmit power in a perpendicular direction.

The rotation of the intermediate shaft about the second direction drives the rotation of the propeller shaft about the third direction to rotate the propeller to move the watercraft. Since the third direction and the first direction are substantially parallel, the intermediate shaft and the propeller shaft are substantially perpendicular. A gear associated with the second end of the intermediate shaft may mesh with a gear associated with the first end of the intermediate shaft. For example, these gears may be bevel and/or helical gears.

The configuration of these shafts allows to efficiently transmit power from the electric motor to the propeller in a compact way. In addition, the rotational speed provided by the electric motor may be adapted to a rotational speed of the propeller. Consequently, the electric motor revolutions per minute provided by the electric motor may be reduced to the propeller shaft revolutions per minute to match the range of revolutions per minute of the propeller. For example, the change of direction of the shafts, e.g. from the input shaft to the intermediate shaft, may be used to reduce the rotational speed.

In some examples, the electric motor is configured to rotate at an electric motor revolutions per minute and the gearbox is configured to reduce the electric motor revolutions per minute to an input shaft revolutions per minute. Different configurations of gearbox may be used to reduce the rotational speed from the electric motor revolutions per minute to the input shaft revolutions per minute.

In some examples, the second end of the input shaft and the first end of the intermediate shaft may be configured to reduce an input shaft revolutions per minute to an intermediate shaft revolutions per minute. A pair of gears, each of them associated with one of the input shaft and the intermediate shaft may be used to reduce the rotational speed and to change the direction of the shafts.

In some examples, the second end of the intermediate shaft and the first end of the propeller shaft may be configured to reduce an intermediate shaft revolutions per minute to a propeller shaft revolutions per minute. For example, a second intermediate shaft gear arranged at the second end of the intermediate shaft may mesh a propeller shaft gear to reduce the revolutions per minute.

According to the present disclosure, the upper supporting structure may be tilted with respect to the watercraft such that the upper supporting structure and the lower supporting structure may be positioned above a water level. The powering system may thus be tilted with respect to the watercraft as a single unit. Consequently, the electric motor, the gearbox, the shafts, and propeller may be easily accessed to perform maintenance operations. Moreover, tilting the powering system above the water level may prevent water from coming into direct contact with the powering system. Consequently, infiltration of moisture or water to internal critical areas of the powering system may be avoided and thus, corrosion and wear may be reduced. Furthermore, tilting the powering system above the water level may prevent the incrustation of algae and mollusks onto the powering system. Wear may thus be reduced, and performance of the powering system may be improved.

As the lower supporting structure is rotatably coupled to the upper supporting structure, the propeller may rotate relative to the upper structure. Accordingly, only the rotation of the lower structure may be required to perform steering operations. Consequently, loads required to steer the propeller may be decreased. In addition, drag may be reduced and loads required to maintain a predetermined steering angle or steering direction may be decreased.

In some examples, the powering system may further comprise a bearing rotatably coupling the lower supporting structure to the upper supporting structure. Examples of suitable bearings may be roller bearings and gliding pad bearings.

To allow the lower supporting structure to rotate relative to the upper supporting structure, the intermediate shaft comprises an upper portion that can rotate relative to the lower portion about the second direction. The lower portion may thus be driven by the upper portion and rotate with respect to the upper portion about the second direction. Axis of rotation of the lower portion and of the upper portion are thus parallel to the second direction. In some examples, the intermediate shaft may comprise a universal joint rotatably coupling the upper portion to the lower portion of the intermediate shaft.

In some examples, the powering system may further comprise a steering system to rotate the lower supporting structure about the upper supporting structure. The steering system orientates the lower supporting structure to position the propeller at a predetermined direction, i.e. the steering angle. The steering system may comprise an actuator to cause the rotation of the lower support structure about the upper support structure. The actuator may have a first end coupled to the upper supporting structure and a second end coupled to the lower supporting structure. When the actuator changes its length, the actuator may push or pull its second end coupled to the lower supporting structure. As the lower supporting structure is rotatably coupled to the upper supporting structure, the actuator by changing its length rotates the lower supporting structure about the upper supporting structure. Since the steering system may only rotate the lower supporting structure, loads required to rotate may be reduced. Accordingly, relatively small actuators may be used.

In a further aspect, a watercraft comprising a hull and the powering system according to any of examples herein disclosed is provided. The hull extends from a port side to a starboard side along a port - starboard direction and from a bow to a stern along a bow - stern direction, the hull comprising a coupling portion. In this aspect, the upper supporting structure of the powering system is tiltable coupled to the coupling portion of the hull.

Advantages derived from this second aspect may be similar to those mentioned regarding the powering system of the first aspect. Namely, saving space inside the hull, simplifying the installation of the powering system, improving maintenance, and decreasing loads required to maintain the steering angle. Furthermore, corrosion and wear may be prevented, e.g. when the powering system is tilted above the water level.

In some examples, the coupling portion may be integrated within the hull. In further examples, the coupling portion may be attached to the hull, e.g. to the stern side of the hull.

In some examples, the watercraft comprises a positioning system to position the power system relative to the water level. The positioning system may thus tilt the powering system with respect to the hull. The positioning system may be arranged at the hull of the watercraft. In some examples, the positioning system may be fixedly coupled to the hull of the watercraft. Alternatively, the positioning system may be placed on the hull when tilting the powering system is required. Rotatory actuators and/or linear actuators may be used to rotate the powering system about an axis parallel to the port - starboard direction, i.e. for tilting the powering system.

In some examples, the upper supporting structure may comprise a mounting bracket to support a connecting member for connecting the upper supporting structure to the watercraft. The connecting member may connect the coupling portion of the hull to the mounting bracket of the upper supporting structure. The connecting member may be rotatably coupled to the coupling portion of the hull to allow the upper supporting structure to tilt about the watercraft.

In some of these examples, the mounting bracket may be fixedly connected to the connecting member which extends in a direction parallel to the port-starboard direction. A rotatory actuator may be employed to rotate the connecting member so as to rotate rotating the powering system about an axis parallel to the port - starboard direction.

Alternatively, the connecting member comprises a first end rotatably coupled to the coupling portion of the hull and a second end rotatably coupled to the mounting bracket of the upper supporting structure. The connecting member may rotate with respect to the coupling portion about a connecting member first end axis and with respect to the mounting bracket about a connecting member second end axis. The connecting member first end axis and the connecting member second end axis may be substantially parallel to the port - starboard direction. Furthermore, the connecting member first end axis may be spaced apart a distance from the connecting member second end axis. Accordingly, the upper supporting structure may rotate about the connecting member first end axis and about the connecting member second end axis. The connecting member first end axis and the connecting member second end axis are separated by a distance substantially corresponding to the length of the connecting member. This increases the precision of the height of the propeller relative to the water level. For example, this arrangement allows performing large tilting and/or trimming operations Therefore, the position of the propeller shaft relative to the watercraft may be modified or adjusted to the water level.

In these figures the same reference signs have been used to designate matching elements.

<FIG> illustrates a simplified view of one example of a powering system <NUM> comprising an electric motor <NUM> and a gearbox <NUM> coupled to the electric motor <NUM>. The electric motor <NUM> converts electrical energy into mechanical energy. The electric motor <NUM> may be an alternating current (AC) motor (e.g. asynchronous motor, synchronous motor) comprising a rotor encircled by a stator. The stator is a stationary element, and the rotor is the rotating element. The rotor may be rotatably mounted on the stator through a bearing so that the rotor may rotate relative to the stator around an axis. On the one hand, the stator comprises slots for receiving winding which passes through the slots of the stator. On the other hand, the rotor comprises an electric motor shaft <NUM>. When an AC current passes through the winding of the stator, a rotating magnetic field is generated. As a result, current is induced in the rotor which results in an induced magnetic field around the rotor. The interaction of the rotating magnetic field and the induced magnetic field results in the rotation of the rotor about the axis of the electric motor shaft <NUM>. Therefore, the electric motor <NUM> may be configured to rotate the electric motor shaft <NUM> at an electric motor revolutions per minute.

The electric motor revolutions per minute may be understood as the number of turns of the electric motor shaft <NUM> in one minute.

The gearbox <NUM> is coupled to the electric motor shaft <NUM> of the electric motor <NUM> through a shaft coupling. The gearbox <NUM> may be a reduction gearbox arranged to reduce the electric motor revolutions per minute.

In some examples, the gearbox <NUM> may be a reduction gearbox comprising epicyclic gearing. The epicyclic gearing may include a sun gear, one or more planet gears, a ring gear, and a carrier element supporting the planet gears.

The sun gear may be coupled to the electric motor shaft <NUM> such that the rotation of the electric motor shaft <NUM> may be transferred to the sun gear. The sun gear may rotate about a sun gear axis at the electric motor revolutions per minute.

The sun gear may engage the planet gears. The sun gear and the planets gears may include gear teeth such that the gear teeth of the sun gear mesh with the gear teeth of the planet gears.

The planet gears may be arranged between the sun gear and an inner surface of the ring gear. The inner surface of the ring gear may include gear teeth configured to mesh with the gear teeth of the planet gears.

Upon rotation of the sun gear, the planet gears may rotate concentrically about the sun gear axis and revolve externally of the sun gear and internally of the ring gear. Thus, rotation of the planet gears may rotate the carrier element about the sun gear axis.

The gear ratio e.g. sun gear relative to the planet gears, sun gear relative to the ring gear, may be selected to reduce the electric motor revolution per minute to predetermined revolutions per minute.

In this example, the ring gear is stationary (i.e. the ring gear does not rotate about the axis of the sun gear). During operation of the gearbox of the <FIG>, the sun gear may be rotated by the electric motor shaft rotating at the electric motor revolutions per minute. In this example, the sun gear meshes with the planet gears and the planet gears rotates concentrically about the axis of the sun gear which in turn rotates the carrier element fixed to the planet gears. As a result, the output of the gearbox <NUM> with epicyclic gearing may rotate at a decreased revolutions per minute than the electric motor revolutions per minute.

The powering system further comprises an input shaft <NUM>, an intermediate shaft <NUM> and a propeller shaft <NUM>. The input shaft <NUM> extends from a first end <NUM> to a second end <NUM> in a first direction <NUM>.

The first end <NUM> of the input shaft is coupled to the gearbox <NUM>. Thus, the gearbox <NUM> may reduce the rotational speed of the electric motor revolutions per minute to an input shaft revolutions per minute. The input shaft revolutions per minute may be understood as the number of turns of the input shaft <NUM> in one minute. Therefore, the input shaft <NUM> coupled to gearbox through the first end <NUM> may perform a number of turns in one minute that is lower to the number of turns of the electric motor shaft in one minute.

In this example, the electric motor <NUM> rotates at an electric motor revolutions per minute and the gearbox <NUM> reduces the electric motor revolutions per minute to an input shaft revolutions per minute.

In this figure, the intermediate shaft <NUM> comprises a first end <NUM> and a second end <NUM>. The intermediate shaft <NUM> further comprises an upper portion <NUM> and a lower portion <NUM>. The upper portion <NUM> extends in a second direction <NUM> and the propeller shaft <NUM> extends from a first end <NUM> to a second end <NUM> in a third direction <NUM>.

The first direction <NUM> is perpendicular to the second direction <NUM> and parallel to the third direction <NUM>. Consequently, the input shaft <NUM> is substantially perpendicular to the intermediate shaft <NUM>. Furthermore, the input shaft <NUM> is substantially parallel to the propeller shaft <NUM>.

The first end <NUM> of the intermediate shaft <NUM> is rotatably coupled to the second end <NUM> of the input shaft <NUM> through a first coupling mechanism <NUM>.

The first coupling mechanism <NUM> may comprise an input shaft gear and a first intermediate shaft gear. The input shaft gear may mesh with the first intermediate shaft gear (not visible in <FIG>). The second end <NUM> of the input shaft <NUM> may comprise the input shaft gear and the first end <NUM> of the intermediate shaft <NUM> may comprise the first intermediate shaft gear.

In some examples, the input shaft gear and the first intermediate shaft gear may be e.g. bevel gears, helical bears, and/or worm gear for changing the direction of the input shaft extending in the first direction <NUM> to the direction of the upper portion of the intermediate shaft extending in the second direction <NUM>.

The gear ratio of the input shaft gear and the first intermediate shaft gear may be suitable to reduce the rotational speed of the input shaft revolution per minute to a specific intermediate shaft revolutions per minute, i.e. the number of turns of the intermediate shaft <NUM> in one minute.

Therefore, the second end <NUM> of the input shaft <NUM> and the first end <NUM> of the intermediate shaft <NUM> may be configured to reduce an input shaft revolutions per minute to an intermediate shaft revolutions per minute.

As herein before mentioned, the intermediate shaft <NUM> comprises the upper portion <NUM> and the lower portion <NUM>. In this example, the lower portion <NUM> is rotatably coupled to the upper portion <NUM> through a universal joint <NUM>. The universal joint <NUM> permits the rotation of the lower portion <NUM> relative to the upper portion <NUM> about the second direction <NUM>. A torque and/or rotary motion may be transmitted from the upper portion <NUM> to the lower portion <NUM>.

In some examples, the universal joint <NUM> may be a variable velocity joint e.g. cardan joint, cross joint, ball and trunnion joint for transmitting torque and/or rotary motion from the upper portion <NUM> to the lower portion <NUM> through a variable angle at a variable rotational speed.

Alternatively, the universal joint <NUM> may be a constant velocity joint e.g. double cardan joint, Tracta joint, Rzeppa joint, Birfield joint, Weiss joint, tripod joint, Malpezzi joint, and/or Thompson joint.

In addition, the universal joint <NUM> may allow small angle variations between the upper portion <NUM> and the lower portion <NUM>. The upper portion <NUM> extends along an upper portion axis <NUM>. The upper portion axis <NUM> may be substantially parallel to the second direction <NUM>. Similarly, the lower portion <NUM> extends along a lower portion axis <NUM>. In this figure, the lower portion axis <NUM> may be substantially parallel to the upper portion axis <NUM> and/or to the second direction <NUM>.

In some examples, the lower portion axis <NUM> may form an angle with the upper portion axis <NUM>. This angle may adopt an angle between +<NUM>° and +<NUM>°. Consequently, the input shaft <NUM> extending in the first direction <NUM> is substantially parallel to the propeller shaft <NUM> extending in the third direction <NUM>.

In this figure, the first end <NUM> of the propeller shaft <NUM> is rotatably coupled to the second end <NUM> of the intermediate shaft <NUM> through a second coupling mechanism <NUM>.

The second coupling mechanism <NUM> may comprise a second intermediate shaft gear arranged at the second end <NUM> of the intermediate shaft <NUM> meshing with a propeller shaft gear arranged at the first end <NUM> of the propeller shaft <NUM> (not visible in <FIG>).

The second intermediate shaft gear and the propeller shaft gear may be e.g. bevel gears, helical bears, and/or worm gear for changing the direction of the intermediate shaft extending in the second direction <NUM> to the direction of the propeller shaft extending in the third direction <NUM>.

The gear ratio of the second intermediate shaft gear and the propeller gear may be selected to reduce the rotational speed of the intermediate shaft revolution per minute. As a result, the second intermediate shaft gear and the propeller gear may reduce the intermediate shaft revolutions per minute to a propeller shaft revolutions per minute, e.g. the number of turns of the propeller shaft <NUM> in one minute.

Therefore, the second end <NUM> of the intermediate shaft <NUM> and the first end <NUM> of the propeller shaft <NUM> may be configured to reduce an intermediate shaft revolutions per minute to a propeller shaft revolutions per minute.

The second end <NUM> of the propeller shaft <NUM> is coupled to a propeller assembly <NUM> of the powering system <NUM>. In this example, the propeller assembly <NUM> comprises a first propeller <NUM> and a second propeller <NUM>. The second end <NUM> of the propeller shaft <NUM> may be coupled to a first propeller <NUM>. A shaft may connect the first propeller <NUM> to the second propeller <NUM>. The propeller shaft <NUM> may be coupled to a propeller assembly <NUM> such as the electric motor revolutions per minute may be reduced to the propeller shaft revolutions per minute to match the range of revolutions per minute of the propeller.

In some examples, the propeller shaft <NUM> may be coupled to the first propeller <NUM> and/or the second propeller <NUM>.

Furthermore, the powering system <NUM> comprises an upper supporting structure <NUM> and a lower supporting structure <NUM>.

The lower supporting structure <NUM> may be substantially cylindrical or comprising a hollow interior with an inner surface. The inner surface of the lower supporting structure <NUM> may comprise supports for supporting and receiving the propeller shaft <NUM> and the propeller assembly <NUM> such that the inner surface of the lower supporting structure supports the propeller shaft <NUM> and the propeller assembly <NUM>.

The lower supporting structure <NUM> thus supports the propeller shaft <NUM> and the propeller <NUM>. In some examples, the second coupling mechanism <NUM> is also supported by the lower supporting structure <NUM>, i.e. the lower supporting structure <NUM> may further support the second end <NUM> of the intermediate shaft <NUM> and the first end <NUM> of the propeller shaft <NUM>.

As explained before, the lower supporting structure <NUM> is rotatably coupled to the upper supporting structure <NUM> to rotate about the second direction <NUM>. In some examples, a bearing may be arranged to rotatably coupling the lower supporting structure <NUM> to the upper supporting structure <NUM>.

In some of these examples, the bearing comprises a first bearing component and a second bearing component. The first bearing component may be coupled to the lower supporting structure <NUM> whereas the second bearing component may be coupled to the upper supporting structure120. A bearing element may be arranged between the first bearing component and the second bearing component; such that the first bearing component may be configured to rotate with respect to the second bearing component.

The bearing element may comprise e.g. a gliding pad, and/or a rolling element. The gliding pad may reduce the friction between the first bearing component and the second bearing component. Alternatively, or additionally, a rolling element or a plurality of rolling elements may be arranged between the first and the second components to allow the rotation of the lower supporting structure about the second direction.

The upper supporting structure <NUM> may be substantially cylindrical or comprising a hollow interior. The inner surface of the upper supporting structure <NUM> may comprise supports for holding the electric motor <NUM> and the gearbox <NUM> such that the inner surface of the upper supporting structure supports the electric motor <NUM> and the gearbox <NUM>.

The upper supporting structure <NUM> thus supports the electric motor <NUM> and the gearbox <NUM>. In some examples, the upper supporting structure <NUM> may further support the input shaft <NUM> and the upper portion <NUM> of the intermediate shaft <NUM>.

In addition, additional components may be supported by the upper supporting structure <NUM>, e.g. the first coupling mechanism <NUM>, the input shaft gear and/or the first intermediate shaft gear.

In this example, the upper supporting structure <NUM> houses and covers the electric motor <NUM>, the gearbox <NUM>, the input shaft <NUM> and the upper portion <NUM> of the intermediate shaft <NUM>. The lower supporting structure <NUM> of this figure, houses and covers the lower portion <NUM> of the intermediate shaft and the propeller shaft <NUM>. These components are thus respectively protected by the upper supporting structure <NUM> and the lower supporting structure <NUM>. In addition, the lower supporting structure <NUM> supports the propeller assembly <NUM>.

In some examples, the lower supporting structure may further support e.g. the second coupling mechanism <NUM>, the second intermediate shaft gear and/or the propeller shaft gear.

A sealing member may be arranged between the upper supporting structure <NUM> and the lower supporting structure to prevent water from entering inside these supporting structures.

In <FIG>, the upper supporting structure <NUM> comprises a mounting bracket <NUM> to support a connecting member for connecting the upper supporting structure <NUM> to a watercraft. Thus, a connection between the upper supporting structure <NUM> and the watercraft may be established. This connection allows the upper supporting structure to be tiltable coupled to the watercraft. The upper supporting structure <NUM> may be tilted such that the upper supporting structure <NUM> and the lower supporting structure <NUM> may be positioned above a water level. Thus, the electric motor, the gearbox, the shafts, and propeller may be easily accessed to perform maintenance.

<FIG> shows a watercraft <NUM> comprising a powering system <NUM> according to any of the examples herein disclosed. The watercraft <NUM> comprises a hull <NUM> extending from a port side <NUM> to a starboard side <NUM> along a port - starboard direction <NUM> and from a bow <NUM> to a stern <NUM> along a bow -stern direction <NUM>. The powering system <NUM> is tiltable coupled to a coupling portion <NUM> of the hull <NUM>.

The powering system may be coupled to the coupling portion of the hull according to any of the examples herein disclosed. In this example, the length of the watercraft may be between <NUM> and <NUM> meters. In some examples, the length of the watercraft may be comprised between <NUM> and <NUM> meters.

<FIG> respectively shows a top side view of a powering system <NUM> according to one example of the present disclosure at different steering angles. <FIG> illustrate a steering system <NUM> for steering operations i.e. rotating the lower supporting structure <NUM> about the upper supporting structure <NUM>.

In this example, the steering system <NUM> comprises a pair of actuators, a port side actuator <NUM> and a starboard side actuator <NUM>. However, in other examples, the steering system may comprise a single actuator. Each of the actuators <NUM>, <NUM> of these figures has a first end <NUM>, <NUM> coupled to the upper supporting structure <NUM> and a second end <NUM>, <NUM> coupled to the lower supporting structure <NUM>.

A length may be defined for each of the actuators between from the corresponding first end <NUM>, <NUM> to the corresponding second end <NUM>, <NUM>. The length of these actuators may be changed, i.e. extended or reduced. By controlling the length of each of the two actuators <NUM>, <NUM> of these figures, the lower supporting structure <NUM> rotates about the second direction. The actuators <NUM>, <NUM> may thus push or pull its respective second ends <NUM>, <NUM> to rotate the lower supporting structure <NUM> relative to the upper supporting structure <NUM>.

The steering angle <NUM> may be defined as the angle defined by the first direction <NUM> and the third direction <NUM>. The steering angle <NUM> is the angle adopted by the propeller assembly <NUM> to steer or to guide the watercraft. In <FIG> the steering angle <NUM> is about <NUM>° and in <FIG> about -<NUM>°. The steering angle <NUM> may be varied to steer the watercraft to a specific direction. The steering angle may adopt an angle between +<NUM>° and - <NUM>°, optionally between +<NUM>° and - <NUM>°.

In <FIG>, the port side actuator <NUM> is extended and the starboard side actuator <NUM> is compressed to cause the rotation of the lower supporting structure <NUM> in counterclockwise direction. Contrary, in <FIG> the port side actuator <NUM> is compressed and the starboard side actuator <NUM> is extended to rotate the lower supporting structure <NUM> in clockwise direction.

Therefore, the actuators <NUM>, <NUM> may be configured to change its length to cause the rotation of the lower supporting structure <NUM> about the upper supporting structure <NUM>, enabling steering operations. Loads require for steering operations may be reduced as the steering system <NUM> of these figures only rotates the lower supporting structure <NUM>. This may allow using relatively small actuators.

The actuators <NUM>, <NUM> of these figures are linear actuators, e.g. hydraulic and/or pneumatic actuators. However, other suitable actuators may also be used.

In some examples, the steering system <NUM> may comprise a rotary actuator, and a circular rack and pinion system. In this example the rotary actuator may comprise a body fixedly coupled to the upper supporting structure and a rotary actuator shaft coupled to the pinion. The pinion may engage the circular rack coupled to the lower supporting structure. The rotary actuator may be configured to rotate the circular rack through the pinion to cause the rotation of the lower supporting structure about the upper supporting structure, enabling steering operations. In this example, the steering angle may adopt an angle between +<NUM>° and - <NUM>°.

In this figure, the upper supporting structure <NUM> includes a mounting bracket <NUM>. The mounting bracket <NUM> comprises a port side bracket <NUM> and a starboard side bracket <NUM>, situated at opposite sides of the upper supporting structure <NUM>. In this example, the mounting bracket <NUM> receives a connecting member <NUM> to be coupled to the watercraft.

In some examples, like this figure, the connecting member <NUM> extends in a direction parallel to the port - starboard direction. The connecting member <NUM> of this example comprises a tubular shape. In this figure, the connecting member <NUM> is fixedly attached to the mounting bracket <NUM>. The connecting member <NUM> may be connected to the port side bracket <NUM> and to the starboard side bracket <NUM>. Welding, bolting, using poke yoke elements or shrinking the tube in a through-hole of the brackets may be used to connect the connecting member <NUM> to the brackets.

Alternatively, the connecting member <NUM> may extend in a direction substantially parallel to the bow-stern direction.

<FIG> show a side view of a powering system coupled to a watercraft at different positions. The powering system of these figures may comprise a steering system according to any of the examples herein disclosed. The powering system <NUM> of these figures is rotatably coupled to the hull <NUM> of the watercraft. The axis of the propeller (parallel to the third direction <NUM>) is substantially parallel to the water level <NUM> in <FIG> and forms an angle <NUM> with the water level <NUM>. The powering system <NUM> of these figures rotates about an axis parallel to the port - starboard direction.

In <FIG>, the powering system <NUM> is coupled to the hull <NUM> such that the distance between the stern <NUM> of the hull <NUM> and intermediate shaft (not shown in this figure) is greater than <NUM>, optionally, between <NUM> and <NUM>.

The powering system <NUM> of <FIG> is in a trimmed position. The inclination of propeller shaft is thus adjusted to the water level <NUM> to navigate under specific conditions. In <FIG> the angle <NUM> is about <NUM>°. In <FIG>, the powering system is a tilted position. The powering system is lifted above the water level as a single unit. In this position, the propeller assembly is not in contact with the water level. As a result, infiltration of moisture or water to internal critical areas of the powering system <NUM> may be avoided and thus, corrosion and wear may be reduced. Furthermore, when the powering system is lifted above the water level as a single unit, incrustation of algae and mollusks onto the powering system <NUM> may be avoided. Wear may thus be reduced, and performance of the powering system <NUM> may be improved. The angle <NUM> of <FIG> is about <NUM>°. In these figures, the angle <NUM> may be varied between - <NUM>° to + <NUM>°. This range allows performing trimming and tilting operations.

In these figures, the hull <NUM> comprises a coupling portion <NUM>. The powering system <NUM> is coupled to the hull <NUM> through the connecting member <NUM>. The connecting member <NUM> connects the coupling portion <NUM> of the hull <NUM> to the mounting bracket of the upper supporting structure <NUM> of the powering system <NUM>. In these figures, the connecting member <NUM> extends in a direction parallel to the port-starboard direction and is fixedly connected to the mounting bracket, e.g. welded or bolted. The rotation of the connecting member allows the upper supporting structure to tilt about the watercraft. Therefore, the entire powering system <NUM> can be tilted to the hull <NUM>. The powering system is thus hingedly connected to the watercraft.

In these figures, the coupling portion <NUM> of the hull <NUM> comprises a pair of plates, each of them having a through-hole to receive the connecting member <NUM>. The connecting member can thus be rotated about these through-holes. The plates may be of any suitable material to reinforce the coupling portion <NUM>.

The connecting member <NUM> of these figures may be a single tubular shaft extending from one side to the opposite side of the powering system. However, in further examples, the connecting member may comprise a port side connecting member extending from the port side of the powering system and a starboard side connecting member extending from the starboard side of the powering system.

The powering system of these figures comprises a positioning system <NUM> to position the powering system <NUM> relative to the water level <NUM>. The positioning system <NUM> of these figures may perform tilting operations such as in <FIG>; and/or trimming operations such as in <FIG>.

In these figures, the positioning system <NUM> comprises a linear actuator <NUM> that changes its length to cause the rotation of the powering system about an axis parallel to the port - starboard direction. The linear actuator <NUM> comprises a first end <NUM> and a second end <NUM>. One end <NUM> of the linear actuator <NUM> is attached to the hull <NUM> and the other end <NUM> is attached to the upper supporting structure. When the actuator <NUM> changes its length, the actuator may push or pull its second end <NUM> coupled to the upper supporting structure. Therefore, the linear actuator <NUM> is configured to change its length to rotate the powering system <NUM> about an axis parallel to the port - starboard direction. The length of the linear actuator <NUM> thus defines the angle <NUM>.

Alternatively, or additionally, the positioning system may comprise a rotatory actuator engaging the connecting member <NUM>. The rotation of the rotatory actuator induces the rotation of the connecting member <NUM>. When the connecting member is rigidly attached to the powering system <NUM>, the rotation of the connecting member induces the rotation of the entire powering system <NUM>.

The positioning system may comprise a controller to control the operation of the actuator(s). For example, the controller may control the length of the linear actuator so as to position the powering system at a predetermined angle.

<FIG> respectively shows a side view of a powering system coupled to a watercraft according to one example of the present disclosure at different positions. These figures also include a zoom-in view of the connecting member <NUM>. The powering system of these figures may be similar to the powering system depicted in <FIG>. However, in <FIG>, the connecting member <NUM> is rotatably connected to the upper supporting structure.

In these figures, the connecting member <NUM> extends from a connecting member first end <NUM> to a connecting member second end <NUM>. The connecting member of these figures is substantially bar shaped. The connecting member <NUM> of these figures comprises port side connecting member and a starboard connecting member. In these figures only the port side connecting member is illustrated. The connecting member first end <NUM> is rotatably coupled to the coupling portion <NUM> of the hull <NUM> to rotate about a connecting member first end axis <NUM>. A hinged connection is thus formed between the connecting member first end <NUM> and coupling portion <NUM> of the hull <NUM>.

The connecting member second end <NUM> is rotatably coupled to the mounting bracket of the upper supporting structure <NUM> of the powering system <NUM> forming a hinge connection that allows the connecting member <NUM> to rotate about a connecting member second end axis <NUM>. The connecting member first end axis <NUM> and connecting member second end axis <NUM> are substantially parallel to the port - starboard direction. The connecting member first end axis <NUM> may be substantially parallel to the port - starboard direction. These axes are spaced apart.

The connecting member <NUM> of these figures increases the number of possible positions of the powering system relative to the watercraft and to the water level. As in other examples, the whole powering system may be rotated about the watercraft. In addition, in these figures the distance between the powering system and the stern may adjusted. Furthermore, the height of the powering system relative to the watercraft may be adjusted to the type of navigation, as illustrated in <FIG> and <FIG>.

In <FIG> and <FIG> the third direction <NUM> is substantially parallel to the water level <NUM>. However, the height, i.e. the vertical distance, of the powering system with respect to the watercraft is greater in <FIG> than in <FIG>. The powering system of <FIG> is raised when compared to the powering system of <FIG>. In <FIG> the connecting member <NUM> extends substantially parallel to the first direction having the connecting member second end <NUM> above the connecting member first end <NUM>. This position may be used to navigate at relative low speeds.

In <FIG>, the connecting member <NUM> is inclined. The connecting member first end <NUM> is above the connecting member second end <NUM>. This allows adjusting the vertical position of the propeller assembly. This arrangement may be allow using foils in an efficient way.

A plurality of foils may be provided at the hull <NUM> of the watercraft may comprise, for example at the port side and/or the starboard side.

A foil may be understood as a lifting surface that operates in water. As the watercraft moves through the water, the foils deflect the flow of water, which exerts an upward force on the foil lifting the hull above the water level <NUM>. The position of figure 4d allows maintaining the propeller assembly below the water level <NUM>. Therefore, a sufficient thrust force may be maintained. The lifting effect of the foils may thus be compensated by the capacity of the propeller system to adjust the vertical position of the propeller assembly.

In this <FIG>, the water level <NUM> is below the hull. In this figure, a foil coupled to the hull lifts the hull above the water level <NUM>. However, in some examples, depending on navigation conditions the lowest side of the hull may be below the water level <NUM>.

The powering system <NUM> of <FIG> is in a trimmed position in which the inclination of the propeller shaft is adjusted to navigated under specific conditions. Similar to <FIG>, the angle <NUM> is about <NUM>°. As in <FIG>, the powering system <NUM> of <FIG> is in a tilted position with an angle <NUM> about <NUM>°. The angle <NUM> may vary between - <NUM>° to + <NUM>°.

In this <FIG>, the lowest side of the hull is below the water level <NUM>. However, in some examples, depending on navigation conditions, the water level <NUM> may be below the hull.

The powering system <NUM> of these figures comprises positioning system <NUM> comprising a linear actuator <NUM> and a rotatory actuator (not shown in these figures). The rotatory actuator is configured to control the rotation of the connecting member first end <NUM> about the connecting member first axis <NUM>. The rotatory actuator may comprise a motor arranged at the watercraft driven a shaft that is rigidly connected to the connecting member first end <NUM>. The motor thus caused the rotation of the connecting member <NUM> about the connecting member first axis <NUM>.

The linear actuator <NUM> comprises a first end <NUM> coupled to the hull and a second end <NUM> coupled to the upper supporting structure. The linear actuator may change the length between the two ends. A change of the length of the linear actuator may cause the rotation of the powering system relative to the watercraft.

In these figures, the positioning system <NUM> comprises a controller to control the operation of the linear actuator <NUM> and the rotatory actuator.

The controller may be configured to selectively operate the rotatory actuator to rotate the connecting member <NUM> about the connecting member first end axis <NUM> and selectively operate the linear actuator <NUM> to change its length to rotate the upper supporting structure about the connecting member second end axis <NUM>. By controlling the operation of these two types of actuators, a plurality of precise positions may be reached as shown in <FIG>.

For example, the controller may maintain the rotatory actuator at a fixed position, i.e. not rotating, and increase the length of the linear actuator. In this way, the connecting member <NUM> only rotates about the connecting member second axis <NUM> due to the action of the linear actuator. Or, if the linear actuator is not actuated, i.e. its length is not changed, but the rotatory actuator rotates the connecting member first end <NUM>, the entire powering system is rotated about the connecting member first axis <NUM>.

The controller may also rotate the rotatory actuator and actuate the linear actuator. The powering system may be rotated about the connecting member first axis <NUM> and about the connecting member second axis <NUM> from a first position to a second position.

<FIG> shows a cross-sectional view of a powering system <NUM> according to an example of the present disclosure. The powering system <NUM> of <FIG> may be according to any of the examples herein disclosed. For example, the powering system <NUM> may comprise the connecting member and/or the steering system according to any of the examples herein disclosed.

In this figure, the powering system <NUM> comprises an electric motor <NUM> and a gearbox <NUM>. The electric motor <NUM> of this figure is an asynchronous motor, however, in other examples, other suitable electric motors may be employed. The gearbox <NUM> of this example is an epicyclic gearing.

In this figure, the powering system <NUM> further comprises the input shaft <NUM>, the intermediate shaft <NUM>, a first propeller shaft <NUM> having a first end <NUM>, and a second propeller shaft <NUM> having a first end <NUM>. The first propeller shaft <NUM> and the second propeller shaft <NUM> extends in the third direction.

The first end <NUM> of the input shaft <NUM> is coupled to the gearbox and is surrounded by a first input shaft support element <NUM>. The second end <NUM> of the input shaft <NUM> is rotatably coupled to the first end <NUM> of the intermediate shaft <NUM>.

The first input shaft support element <NUM> and the second input shaft support element <NUM> support the input shaft <NUM>. The first input shaft support element <NUM> and the second input shaft support element <NUM> comprise a bearing having an outer ring and an inner ring. The outer ring is connected to the inner surface of the upper supporting structure <NUM> and the inner ring is respectively connected to the first end <NUM> and to the second end <NUM> of the input shaft <NUM>.

An input shaft gear <NUM> is arranged at the second end <NUM> of the input shaft. The input shaft gear <NUM> meshes with a first intermediate shaft gear <NUM>. The first intermediate shaft gear <NUM> may additionally mesh with a first intermediate shaft gear support element <NUM>. The first intermediate shaft gear support element <NUM> comprises a gear that meshes with the first intermediate shaft gear <NUM>. The first intermediate shaft gear support element <NUM> comprises a bearing that allows the gear to rotate about the first direction. The first intermediate shaft gear <NUM> of this figure is arranged between the input shaft gear <NUM> and the first intermediate shaft gear support element <NUM>. Misalignments of the upper portion <NUM> intermediate shaft are thus prevented.

In addition, the powering system of this figure comprises a first intermediate shaft support element <NUM> to rotatably support the upper portion <NUM> of the intermediate shaft. This support element comprises a bearing having an inner ring connected to the end of the upper portion <NUM> of the intermediate shaft and an outer ring connected to the upper supporting structure.

Between the upper portion <NUM> and the lower portion <NUM> of the intermediate shaft a double cardan joint <NUM> is provided. In other examples, the upper portion <NUM> and the lower portion <NUM> may be coupled according to any of the examples herein disclosed.

The double cardan joint <NUM> allows the lower portion <NUM> to rotate about the upper portion <NUM> of the intermediate shaft. In this figure, a bearing <NUM> connects the upper supporting structure <NUM> with the lower supporting structure <NUM>.

The lower portion <NUM> of the intermediate shaft is rotatably coupled to the first end <NUM> of the first propeller shaft <NUM>. A second intermediate shaft support element <NUM> supports and aligns the lower portion <NUM> of the intermediate shaft.

A second intermediate shaft gear <NUM> is arranged at the end of the lower portion <NUM> of the intermediate shaft and meshes with a first propeller shaft gear <NUM> arranged at the first end <NUM> of the first propeller shaft <NUM>. In this figure, the second intermediate shaft gear <NUM> meshes with a second propeller shaft gear <NUM>. The second propeller shaft gear <NUM> is arranged at the first end <NUM> of the second propeller shaft <NUM>. The second propeller shaft gear <NUM> comprises a gear that rotates about the third direction and meshes with the second intermediate shaft gear <NUM>. The second intermediate shaft gear <NUM> of this figure is thus arranged between the second propeller shaft gear <NUM> and the first propeller shaft gear <NUM> such that the first propeller shaft <NUM> and the second propeller shaft <NUM> rotate about the third direction in opposite directions.

In this figure, the first propeller shaft <NUM> is mounted concentrically around the second propeller shaft <NUM>. The first propeller shaft <NUM> and the second propeller shaft <NUM> are coupled for rotation in opposite directions. In this figure, the second propeller shaft <NUM> is positioned inside the first propeller shaft that has a hollow portion arranged for receiving the second propeller shaft <NUM>. In other examples, a different configuration may be employed, for example, a single propeller shaft may be used.

In this figure, the first propeller shaft is coupled to the first propeller <NUM> and the second propeller shaft is coupled to the second propeller.

The first end <NUM> of the first propeller shaft <NUM> passes through a propeller shaft support element <NUM>. The propeller shaft support element <NUM> comprises a bearing having an outer ring and an inner ring. The outer ring is connected to the inner surface of the lower supporting structure <NUM> and the inner ring is connected to the first end <NUM> of the first propeller shaft <NUM>.

The first input shaft support element <NUM>, the second input shaft support element <NUM>, the first intermediate shaft support element <NUM>, the first intermediate shaft gear support element <NUM>, the second intermediate shaft gear support element <NUM> and/or the propeller shaft support element <NUM> may provide support and proper alignment to their respective shaft and/or shaft gear. The gears according to this example, are bevelled gears. In other examples, other types of gears may also be suitable.

<FIG> shows a watercraft <NUM> comprising a powering system <NUM> according to any of the examples herein disclosed. For example, the powering system <NUM> may comprise the connecting member and/or the steering system according to any of the examples herein disclosed. The powering system <NUM> is tiltable coupled to a coupling portion <NUM>.

In this figure, the coupling portion <NUM> is attached to the hull <NUM>. This may allow using different materials for the coupling portion <NUM> and for the hull <NUM>. In other examples, the coupling portion <NUM> may be integrated within the hull <NUM>.

In some examples, the coupling portion <NUM> may comprise a coupling structure e.g. arms, brackets and/or a cast structure.

The coupling portion of <FIG> includes two arms <NUM>, <NUM> extending from the stern <NUM> of the watercraft to a through-hole <NUM> of the coupling portion <NUM>. which is fixedly coupled to the hull <NUM>.

In this figure, the through-hole <NUM> is arranged such that at least one portion of the connecting member <NUM> passes through the coupling portion <NUM>.

Welding, bolting, using poke yoke elements, or shrinking the tube may be used to fixedly couple the arms <NUM>, <NUM> to the stern <NUM>.

The connecting member <NUM> extends in a direction parallel to the port - starboard direction. The connecting member <NUM> of this example comprises a tubular shape. In this figure, the connecting member <NUM> is fixedly attached to the mounting bracket <NUM>. Welding, bolting, using poke yoke elements, or shrinking the tube in a through-hole of the brackets may be used to connect the connecting member <NUM> to the brackets.

Claim 1:
A powering system (<NUM>) for a watercraft comprising:
a propeller;
an electric motor (<NUM>);
a gearbox (<NUM>) coupled to the electric motor (<NUM>);
an input shaft (<NUM>), an intermediate shaft (<NUM>), and a propeller shaft (<NUM>);
the input shaft (<NUM>) having a first end (<NUM>) coupled to the gearbox (<NUM>) and a second end (<NUM>) rotatably coupled to the intermediate shaft (<NUM>), wherein the input shaft (<NUM>) extends from the first end (<NUM>) to the second end (<NUM>) in a first direction (<NUM>);
the intermediate shaft (<NUM>) having a first end (<NUM>) rotatably coupled to the input shaft (<NUM>) and a second end (<NUM>) rotatably coupled to the propeller shaft (<NUM>), wherein the intermediate shaft (<NUM>) comprises an upper portion (<NUM>) and a lower portion (<NUM>), and wherein the upper portion (<NUM>) extends in a second direction (<NUM>);
the propeller shaft (<NUM>) having a first end (<NUM>) rotatably coupled to the intermediate shaft (<NUM>) and a second end (<NUM>) coupled to the propeller, wherein the propeller shaft (<NUM>) extends from the first end (<NUM>) to the second end (<NUM>) in a third direction (<NUM>);
wherein the first direction (<NUM>) is perpendicular to the second direction (<NUM>) and substantially parallel to the third direction (<NUM>); and
an upper supporting structure (<NUM>) supporting the electric motor (<NUM>) and the gearbox (<NUM>), wherein the upper supporting structure (<NUM>) is configured to be tiltable coupled to a watercraft; and
a lower supporting structure (<NUM>) supporting the propeller and the propeller shaft (<NUM>), the powering system being characterized in that:
the lower portion (<NUM>) of the intermediate shaft (<NUM>) is rotatably coupled to the upper portion (<NUM>) of the intermediate shaft and in that the lower supporting structure (<NUM>) is rotatably coupled to the upper supporting structure (<NUM>) to rotate about the second direction (<NUM>).