Propeller system for ship and ship comprising propeller system

Abstract

A propeller system (3) for a ship (1) comprises: a shaft assembly (30), the shaft assembly (30) being coaxial with a propeller axis (X30); a main propeller (40) comprising main blades (41) carried by the shaft assembly (30), each main blade (41) being rotatable relative to the shaft assembly (30) about a respective pitch axis (R41) extending along said main blade (41) between a first pitch orientation and a second pitch orientation; and an auxiliary propeller (50) comprising auxiliary blades (51) carried by the shaft assembly (30), each auxiliary blade (51) being rotatable relative to the shaft assembly (30) about a respective folding axis (R51) perpendicular to the propeller axis (X30) and said auxiliary blade (51) between a deployed orientation and a folded orientation.

Description

Technical Field

[0001] The present disclosure generally relates to marine propulsion. In particular aspects, the present disclosure relates to a propeller system for a vessel and a vessel including the propeller system.

[0002] The present disclosure may be applied to vessels equipped with one or more propeller systems with or without sails. Background Art

[0003] Generally, sailing vessels include a motorized propulsion member, which may include a straight shaft, an S-drive, or an outboard propeller system. Some of these motorized propulsion members sometimes have a single propeller that is fixed, foldable, or feathered. Some feathering propellers may also adjust the pitch not only to reduce drag in the feathered mode but also to optimize performance by adjusting the pitch in the forward mode. Summary of the Invention

[0004] The present invention aims to solve the disadvantages of the prior art in the following way: providing a propeller system for a vessel, so as to reduce both the drag of the propeller system in the towing mode and optimize the performance in the forward mode.

[0005] According to an aspect of the present disclosure, a propeller system for a vessel includes: a shaft assembly coaxial with a propeller axis of the propeller system; a main propeller including main blades carried by the shaft assembly and driven by the shaft assembly to rotate about the propeller axis, each main blade being rotatable relative to the shaft assembly between a first pitch orientation and a second pitch orientation about a respective pitch axis perpendicular to the propeller axis and extending along the main blade; and an auxiliary propeller including auxiliary blades carried by the shaft assembly and driven by the shaft assembly to rotate about the propeller axis, each auxiliary blade being rotatable relative to the shaft assembly between a deployed orientation and a folded orientation about a respective folding axis perpendicular to the propeller axis and the auxiliary blade.

[0006] Accordingly, the technical effects include that the propulsion system is both versatile and optimized for different situations. Accordingly, the technical effects include obtaining a twin-propeller system with low drag.

[0007] For example, in the forward mode in which the propulsion system is rotated by, for example, a motor of a vessel, the main blades may be placed in the second pitch orientation, which may be a forward drive pitch orientation in which the pitch is high. The forward drive pitch orientation may be adjusted depending on the desired speed and / or torque. In the forward mode, the auxiliary blades may be placed in the deployed orientation, which enables the auxiliary propeller to impart hydrodynamic torque when rotated.

[0008] For example, drag of the propeller system can be reduced in a towing mode, in which the boat is propelled by other components (such as sails or another motorized propulsion system similar to or different from the motorized propulsion system discussed above) other than the propulsion system. To this end, the main blades can be placed in a feather pitch orientation, which can be the first pitch orientation or a pitch orientation between the first pitch orientation and the second pitch orientation. Also to reduce drag in the towing mode, the auxiliary blades can be placed in a folded orientation or at least in an intermediate orientation between the deployed orientation and the folded orientation.

[0009] For example, in a power generation mode in which the boat is propelled by other components (such as sails or other propulsion components) and in which the propulsion system drives an energy generator, the main blades can be placed in a regenerative pitch orientation, which can be the first pitch orientation or a pitch orientation between the first pitch orientation and the second pitch orientation. Again here, the regenerative pitch orientation can be adjusted to obtain the most efficient power generation and / or minimize drag. In the power generation mode, the auxiliary blades can be placed in a folded orientation to reduce drag.

[0010] In some examples, the propeller system includes a motor that is operatively coupled to a shaft assembly via a front shaft end of the shaft assembly to drive a main propeller and an auxiliary propeller to rotate about a propeller axis by driving the shaft assembly, wherein the main propeller is positioned between the front shaft end and the auxiliary propeller.

[0011] Accordingly, a technical effect is that the propeller system can enable the auxiliary blades to be folded to the greatest extent.

[0012] In some examples, the motor is an electric motor that is configured to drive the shaft assembly to rotate to propel the boat and is driven by the shaft assembly to rotate to generate electricity.

[0013] Accordingly, a technical effect is that the same motor can perform two functions of driving the propeller system (e.g., in the forward mode) and generating energy (e.g., in the power generation mode), in which the propeller system is driven to rotate by drag, and the boat is propelled by other components other than the propeller system.

[0014] In other examples, a drive motor can be provided to drive the shaft assembly in a drive mode, and a separate generator can be provided to be driven by the shaft assembly in a power generation mode.

[0015] In some examples, the pitch of the main blades is adjustable because each main blade is configured to be positioned at at least one desired pitch orientation between the first pitch orientation and the second pitch orientation.

[0016] Accordingly, the technical effects include optimizing the pitch of the main propeller depending on the intended use, such as optimizing the performance for forward propulsion, reverse propulsion, high speed, low speed, or propulsion using the main propeller for power generation.

[0017] In some examples, the first pitch orientation is the feathering orientation.

[0018] Accordingly, the technical effects include that the main propeller can be oriented in the feathering orientation to reduce drag, particularly in the towing mode, in which the vessel is propelled by other components than the propeller system.

[0019] In some examples, the propeller system includes a differential planetary gear by means of which an electric motor is operatively connected to the main propeller and the auxiliary propeller. In some examples, the front propeller is connected to the ring gear of the differential planetary gear, and the rear propeller is connected to the planet carrier of the planetary gear. In some examples, the differential planetary gear can be compound or can be a two-pinion planetary gear.

[0020] Accordingly, the technical effects are that the differential planetary gear adaptively and automatically distributes the torque imparted by the motor between the front propeller and the rear propeller depending on the current hydrodynamic conditions applied to each of the main propeller and the auxiliary propeller. In some examples, the differential planetary gear can be useful for automatically and adaptively balancing the ratio of the respective torques generated by the main propeller and the auxiliary propeller. In use, the differential planetary gear always strives to achieve the torque ratio it is designed for. Another technical effect includes that the planetary gear can have a high gear ratio such that, in order to obtain a given rotational speed of the main propeller and the auxiliary propeller, the motor can have a high rotational speed. Thus, the motor can generate the torque required to drive the main propeller and the auxiliary propeller while remaining relatively compact. Another technical effect includes that when used in the power generation mode, the front propeller can drive the motor at a high rotational speed through the differential planetary gear such that a generator or an electric motor is efficiently driven to generate electricity. Another technical effect includes that the planetary gear can be configured to cause the main propeller and the auxiliary propeller to rotate in opposite directions or to cause the propellers to rotate in the same rotational direction.

[0021] In some examples, the propeller system includes a brake for fixing or at least braking the rotation of the auxiliary propeller relative to the main propeller about the propeller axis.

[0022] Accordingly, the technical effects include obtaining direct drive of the main propeller and the auxiliary propeller.

[0023] In some examples, the propeller system includes a brake for fixing or at least braking the rotation of the auxiliary propeller relative to the stator of the electric motor or the hull of the vessel or the stern of the vessel about the propeller axis.

[0024] Accordingly, the technical effect includes stopping or slowing the rotation of the auxiliary propeller relative to the hull of the ship.

[0025] In some examples, the main blade and the auxiliary blade are mechanically coupled to each other by a mechanical coupling such that the orientation of the main blade about the pitch axis and the orientation of the auxiliary blade about the folding axis are dependent on each other, i.e., are synchronized. Preferably, however, the mechanical coupling enables independent rotation of the main propeller and the auxiliary propeller about the propeller axis. For example, by the mechanical coupling of the main blade and the auxiliary blade, it can be provided that when the auxiliary blade is in the folded orientation, the main blade is in the regeneration pitch orientation, when the auxiliary blade is in the deployed orientation, the main blade is in the forward drive pitch orientation, and when the auxiliary blade is in an intermediate orientation between the deployed orientation and the folded orientation, the main blade is in the feathering pitch orientation.

[0026] In some examples, the main blade does not have an actuator for being rotated about the pitch axis, and the auxiliary blade does not have an actuator for being rotated about the folding axis, and the main blade and the auxiliary blade are actuated only by dynamic effects applied to the blades (such as by centrifugal effects and / or hydrodynamic forces applied to the main propeller and / or the auxiliary propeller). The centrifugal effect and the hydrodynamic force can place the auxiliary blade in the deployed orientation when the shaft assembly is driven by a motor to rotate. When the shaft assembly is towed with the auxiliary propeller not being driven to rotate about the propeller axis, the towing pulls the auxiliary blade to the folded orientation.

[0027] In some examples, when the propeller system is towed as the ship is driven forward by other components (such as sails), any brakes (if provided) are preferably released. In this configuration, since the centrifugal effect is weak or zero, the auxiliary blade can be pulled by the hydrodynamic force applied to the auxiliary blade to an intermediate orientation between the folded orientation and the deployed orientation. By being mechanically coupled to the auxiliary blade, the main blade is placed in the feathering pitch orientation. Thereby, the overall drag of the propeller system is minimized, and the feathering pitch orientation causes the main blade to tend to prevent the rotation of the first propeller. This reduces the need to provide a brake for securing the shaft assembly in the towing mode.

[0028] In some examples, when the propeller system is driven by a motor to rotate, any brakes (if provided) are preferably released. In this configuration, the auxiliary blade can be placed in the deployed orientation due to the centrifugal effect. By being mechanically coupled to the auxiliary blade, the main blade is placed in the forward drive pitch orientation.

[0029] In some examples in which the propeller system includes a brake for fixing or at least braking the auxiliary propeller relative to the stator, the hull of the ship, or the stern of the ship, the brake can be applied to obtain a power generation mode. When the brake is applied, the auxiliary propeller is prevented from rotating or is slowed down so that the centrifugal force applied to the auxiliary propeller can reach zero or at least be reduced. The auxiliary blades can be rotated to a folded orientation under the hydrodynamic forces caused by towing. The main blades can be rotated to a regenerative pitch orientation by mechanical coupling with the auxiliary blades. Thus, applying the brake automatically places the propeller system in the power generation mode. In this case, the main propeller drives a motor through a differential planetary gear, while the auxiliary propeller remains stationary and is folded.

[0030] In other examples, the orientation of the main blades and / or the auxiliary blades is actuated by one or more pitch actuators and / or folding / unfolding actuators.

[0031] In some examples, the shaft assembly includes: an outer hub coaxial with the propeller axis, the main propeller being carried and driven by the outer hub; and an inner shaft coaxial with the propeller axis, the inner shaft being rotatably received in the outer hub, the auxiliary propeller being carried and driven by the inner shaft.

[0032] Accordingly, the technical effects include that the lateral and longitudinal bodies of the propeller system are optimized, and the rotational speeds and directions of the main propeller and the auxiliary propeller can be different relative to each other.

[0033] In some examples, the shaft assembly includes an axial bearing inserted between the main propeller and the auxiliary propeller.

[0034] Accordingly, the technical effects include that the main propeller can rotate at a speed very different from the rotational speed of the auxiliary propeller, for example when the auxiliary propeller is stopped from rotating and only the main propeller rotates. It can also be provided that the main propeller and the auxiliary propeller rotate in opposite directions, that is, rotate along opposite rotational directions.

[0035] According to another aspect of the present disclosure, a ship includes at least one propeller system as defined above.

[0036] In some examples, the ship is a sailboat.

[0037] In some examples, the ship is a motorboat without sails.

[0038] Additional features and advantages are disclosed in the following description, claims, and drawings, and will be partly apparent to those skilled in the art or will be recognized by practicing the present disclosure as described herein. Also disclosed herein are a control unit, a computer-readable medium, and a computer program product associated with the technical benefits and corresponding advantages discussed above. Description of the Drawings

[0039] Aspects of the present disclosure cited as examples will be described in more detail below with reference to the accompanying drawings.

[0040] Figure 1 is an exemplary schematic view of a ship including a propeller system according to one example.

[0041] Figure 2 is Figure 1 a longitudinal sectional view of a part of the propeller system of Detailed Description

[0042] The aspects set forth below represent the necessary information that enables a person skilled in the art to practice the present disclosure.

[0043] Figure 1 The hull 2 of a ship 1 equipped with a propeller system 3, which is a twin-propeller system, is shown schematically. The ship 1 can be a sailboat or a motorboat without sails. In the present example, the propeller system 3 can include: an electric motor 5 having a stator 6 and a rotor 7; a differential planetary gear 20 having a sun gear 21, a planetary gear carrier 22, and a ring gear 23; a brake 25; a shaft assembly 30 having an inner shaft 31, an outer hub 32, and an axial bearing 36; a main propeller 40 having main blades 41; an auxiliary propeller 50 having auxiliary blades 51; and a mechanical coupling 60 having a slider 61, a main mechanism 62, and an auxiliary mechanism 63. However, some of these components can be omitted, modified, or replaced.

[0044] The example shown relates to a straight-shaft propeller system. However, the propeller system can be implemented for other types of drive systems, such as inboard drive systems or outboard drive systems.

[0045] Figure 2 The shaft assembly 30 having an inner shaft 31, an outer hub 32, and an axial bearing 36; the main propeller 40 having main blades 41; the auxiliary propeller 50 having auxiliary blades 51; and the mechanical coupling 60 having a slider 61, a main mechanism 62, and an auxiliary mechanism 63 are shown in more detail.

[0046] As explained below, the propeller system 3 is configured to operate in a forward mode, a towing mode, and a power generation mode. In Figure 1 the ship 1 floats in water 9.

[0047] In the example shown, the propeller system 3 defines a propeller axis X30, which is fixed relative to the stator 6 and / or the hull 2, and the shaft assembly 30 and the propellers 40 and 50 are coaxial with the propeller axis. When the ship 1 is used in water 9, the propeller axis X30 can be horizontal or slightly inclined, as in Figure 1 the

[0048] In the case of a stern drive, the axis X30 can be fixed relative to the stern rather than the hull. In the case of an outboard drive, the axis X30 can be fixed relative to the outboard motor housing rather than the hull.

[0049] The ship 1 defines a forward direction X1 oriented from the stern to the bow.

[0050] In the illustrated example, the stator 6 of the motor 5 is attached to the hull 2 of the ship 1. The rotor 7 can be coaxial with the axis X30, as shown, and operatively connected to the shaft assembly 30 (here via the differential planetary gear 20), or can be otherwise positioned and operatively connected to the shaft assembly via an additional angular gear (not shown) that connects the rotor 7 to the differential planetary gear 20.

[0051] In the case of a stern drive system, the stator 6 can be attached to the stern rather than to the hull.

[0052] In the case of an outboard system, the stator 6 can be attached to the outboard motor housing rather than the hull.

[0053] When the motor 5 is powered, the rotor 7 can be driven to rotate relative to the stator 6 under the electromagnetic interaction between the rotor 7 and the stator 6. The rotor 7 can also be driven to rotate by the shaft assembly 30, as explained below, such that the rotation of the rotor 7 relative to the stator 6 generates electricity for the ship 1 through the electromagnetic interaction in the motor 5.

[0054] In the illustrated example, the rotation of the rotor 7 operates about the axis X30, but depending on the configuration of the motor relative to the shaft assembly 30, it can operate about a different rotor axis.

[0055] In this example, the outer hub 32 and the inner shaft 31 of the shaft assembly 30 are coaxial with the propeller axis X30. The inner shaft 31 is received in the outer hub 32, i.e., can rotate relative to the outer hub 32 and the stator 6 about the axis X30. The outer hub 32 can also rotate relative to the inner shaft 31 and the stator 6 about the axis X30.

[0056] In the example, the main propeller 40 is arranged forward, i.e., in the direction X1 relative to the auxiliary propeller 50. The propeller 40 is the forward propeller, and the propeller 50 is the rear propeller.

[0057] The main propeller 40 is attached to the outer hub 32 such that the outer hub 32 carries the main propeller 40, and when the shaft assembly 30 is driven by the motor 5, the propeller 40 can be driven to rotate about the axis X30. In the towing mode and the power generation mode, the propeller 40 can also drive the outer hub 32 to rotate about the axis X30.

[0058] The auxiliary propeller 50 is attached to the inner shaft 31 such that the inner shaft 31 carries the auxiliary propeller 50 and, when the shaft assembly 30 is driven by the motor 5, the propeller 50 can be driven to rotate about the axis X30. In the towing mode, the propeller 50 can also drive the inner shaft 31 to rotate about the axis X30. To carry the propeller 50, the inner shaft 31 can project from the outer hub 32 in a direction opposite to the direction X1. The auxiliary propeller 50 is preferably attached to the projecting portion of the inner shaft 31. For this purpose, the shaft assembly preferably includes an auxiliary hub 35 fixedly attached to the shaft 31 at the projecting portion of the shaft 31. The auxiliary hub 35 is arranged along the axis X30 adjacent to the outer hub 32. The outer hub 32 is positioned relative to the auxiliary hub 35 in the direction X1.

[0059] In the illustrated example, an axial bearing 36 is inserted between the propellers 40 and 50 parallel to the axis X30. As Figure 1 and Figure 2 shown, the axial bearing 36 can be positioned around the inner shaft 31 and axially abuts against the outer hub 32 and the auxiliary hub 35.

[0060] The shaft assembly 30 is connected to the rotor 7 via a differential planetary gear 20 such that the motor 5 can drive the shaft assembly 30 to rotate via the differential planetary gear 20 in the forward mode to propel the boat 1, or can be driven to rotate by the shaft assembly 30 via the differential planetary gear 20 in the power generation mode, and the motor 5 thus generates electricity. Preferably, the differential planetary gear 20 is coaxial with the axis X30, that is, the sun gear 21, the planet carrier 22, and the ring gear 23 are coaxial with the axis X30 and can rotate relative to the axis X30. In this example, the sun gear 21 is fixedly attached to the rotor 7, the planet carrier 22 is fixedly attached to the inner shaft 31 of the shaft assembly 30, and the ring gear 23 is fixedly attached to the outer hub 32 of the shaft assembly 30. In particular, the planet carrier 22 is fixedly attached to the front shaft end 37 of the shaft 31, and the front shaft end 37 is opposed to the projecting portion of the shaft 31 along the axis X31. In a manner known per se, the planet carrier 22 carries one or more planet gears 24 that can rotate relative to the planet carrier 22 about respective planet axes, each planet axis being parallel to the axis X30 and fixed relative to the planet carrier 22, and the planet gears 24 mesh inwardly with the sun gear 21 and outwardly with the ring gear 23. For this purpose, the sun gear 21 has outwardly oriented teeth, and the ring gear 23 has inwardly oriented teeth.

[0061] Depending on the hydrodynamic effects that may impede the rotation of the propellers 40 and 50 about the axis X30, the differential planetary gear 20 adaptively and automatically distributes the torque imparted by the rotor 7 between the propeller 40 (via the outer hub 32) and the propeller 50 (via the inner shaft 31). In other words, a first portion of the torque generated at the rotor 7 is transmitted to the propeller 40, and a second portion is transmitted to the propeller 50, and the ratio between the first portion and the second portion can vary depending on the ratio of the effects respectively impeding the rotation of the propellers 40 and 50. In other words, when the motor 5 powers the rotation of the rotor 7, the differential planetary gear 20 automatically and adaptively balances the ratio of the respective torques generated by the propellers 40 and 50. More precisely, the differential planetary gear 20 adaptively changes the rotational speed of the propellers to satisfy the torque ratio between the propellers 40 and 50, which depends on the design of the planetary gear 20 (specifically, on the respective number of teeth of the sun gear 21, the planetary gears 24, and the ring gear 23).

[0062] If one of the propellers 40 and 50 is completely prevented from rotating about the axis X30, the other of the propellers 40 and 50 can rotate and benefit from all of the torque imparted by the motor 5 via the differential planetary gear 20. The differential planetary gear 20 is mechanically reversible, which means that if one of the propellers (such as the propeller 40) is rotated, the torque is distributed via the differential planetary gear 20 to the motor 5 and the other propeller (such as the propeller 50). If the propeller 50 is prevented from rotating and the propeller 40 is rotated, all of the torque of the propeller 40 is transmitted to the motor 5 via the differential planetary gear 20.

[0063] The brake 25 is configured to fix or at least brake the rotation of the auxiliary propeller 50 relative to the stator 6 about the propeller axis X30 when applied. For the case shown in which the stator 6 is fixed relative to the hull 2, the rotation of the propeller 50 about the axis X30 relative to the hull 2 is fixed or at least slowed down. In other cases in which the stator 6 is movable relative to the hull 2 (such as, for an outboard drive system), the rotation of the propeller 50 about the axis X30 relative to the stator 6 is fixed or at least slowed down. In other cases in which the axis X30 is movable relative to the stator 6 and the hull 2 (such as, for an inboard drive system), the rotation of the propeller 50 about the axis X30 relative to the stern is fixed. When released, it enables the rotation of the propeller 50 about the axis X30 relative to the stator 6. The brake 25 can include a slider that can slide along the axis X30 between Figure 1 the shown release position and the applied position, in the applied position, the brake 25 is coupled to or applies a braking pressure to the gear carrier 22, thereby preventing the gear carrier 22 from rotating since the gear carrier 22 is fixed relative to the hull 2 via the brake 25.

[0064] In this case, when the brake 25 is applied, the torque generated by the motor 5 is fully transmitted to the propeller 40 via the differential planetary gear 20, and the propeller 50 does not rotate. When the brake 25 is applied, the rotation of the propeller 40 obtained by the hydrodynamic force applied to the propeller is fully transmitted to the motor 5 via the differential planetary gear 20, and the propeller 50 does not rotate.

[0065] Alternatively or additionally, the brake can immobilize or at least brake the rotation of the propellers 40 and 50 about the axis X30 such that when the brake is applied, the propellers 40 and 50 always rotate at the same rotational speed relative to the hull 2 about the axis X30. In this case, the brake synchronizes the rotation of the propellers 40 and 50.

[0066] Since the carrier 22 is attached to the shaft 31 at the front shaft end 37 of the shaft 31 and since the ring gear 23 is connected to the outer hub 32, the motor 5 is coupled to the shaft assembly 30 via the front shaft end 37 and the outer hub 32 to drive the propellers 40 and 50 to rotate about the axis X30. Since the propeller 40 is a front propeller and the propeller 50 is a rear propeller, the main propeller 40 is positioned between the front shaft end 37 and the auxiliary propeller 50 and between the differential planetary gear 20 and the auxiliary propeller 50.

[0067] Each main blade 41 is carried by the shaft assembly 30, particularly by the outer hub 32, so as to rotate about the axis X30 together with the outer hub 32. Each blade 41 is radially oriented with respect to the axis X30. Preferably, the main blades 41 are evenly distributed about the axis X30. A plurality of main blades 41, such as two, three, four or more main blades 41, may be provided. Each main blade 41 has a helical profile, i.e., is arched, such that when the propeller 40 and thus the blade 41 are rotated by the motor 5 via the shaft assembly 30, particularly by the outer hub 32, the blade 41 generates a propulsive force directed parallel to the axis X30. Due to the helical profile of the blade, when the propeller 40 is towed in the water 9 along the axis X30, each blade 41 can also be driven to rotate by the water 9 (i.e., by the hydrodynamic force applied to the blade 41). In this case, the propeller 40 can actuate the rotation of the rotor 7 via the differential planetary gear 20 provided that the brake 25 is applied and the rotation of the propeller 50 is blocked or reduced.

[0068] Each main blade 41 can rotate individually relative to the shaft assembly 30, particularly relative to the outer hub 32, between a first pitch orientation and a second pitch orientation about a respective pitch axis R41. In other words, the main propeller 40 has a variable pitch. Each pitch axis R41 is perpendicular to the propeller axis X30, preferably radially of the propeller axis X30, and extends along the associated blade 41, as Figure 1 andFigure 2 as shown

[0069] For example, the first pitch orientation is a regenerative pitch orientation that can be used in a power generation mode or a reverse mode. In the regenerative pitch orientation, the main blade 41 is oriented such that its front side points in a direction opposite to the direction X1. In the power generation mode, the regenerative pitch orientation is most suitable for the propeller 40 to be rotated by hydrodynamic forces when being towed as the ship 1 moves along the direction X1. In the reverse mode, the regenerative pitch orientation is most suitable for propelling the ship backward (i.e., in a direction opposite to the direction X1).

[0070] For example, Figure 1 the second pitch orientation as shown is a forward drive pitch orientation that can be used in a forward mode, in which the blades 41 are oriented such that their front sides point in the direction X1, and is most suitable for propelling the ship along the direction X1.

[0071] Preferably, the pitch orientation of the main blade 41 is adjustable because each main blade 41 is configured to be positioned at at least one desired pitch orientation between the first pitch orientation and the second pitch orientation. In this example, the blade 41 continuously rotates from the first pitch orientation to the second pitch orientation such that the blade 41 can assume any desired pitch orientation between the first pitch orientation and the second pitch orientation. In particular, the blade 41 can reach Figure 2 the feathering pitch orientation between the first pitch orientation and the second pitch orientation as shown. In the feathering pitch orientation, each blade 41 is oriented such that their sides are substantially parallel to the axis X30, i.e., a lateral orientation, such that the drag of the blade 41 parallel to the axis X30 is reduced. When the blades 41 are in the feathering pitch orientation, their drag is maximum in the orthogonal radial direction (i.e., in the rotational direction around the axis X30), thereby tending to prevent the propeller 40 from rotating around the axis X30 due to rotational hydrodynamic forces.

[0072] Each auxiliary blade 51 is carried by the shaft assembly 30, particularly by the inner shaft 31 via the auxiliary hub 35, so as to rotate around the axis X30 together with the inner shaft 31. Preferably, the auxiliary blades 51 are evenly distributed around the axis X30. A number of auxiliary blades 51 can be provided, such as two, three, four or more auxiliary blades 51. Each auxiliary blade 51 has a helical profile, i.e., is arched, such that when the propeller 50 and thus the blade 51 are rotated by the motor 5 through the shaft assembly 30, particularly through the inner shaft 31, the blade 51 generates a propulsive force pointing parallel to the axis X30. Due to the helical profile of the blade, when the propeller 50 is towed in the water 9 along the axis X30, each blade 51 can also be driven to rotate by the water 9 (i.e., by the hydrodynamic forces applied to the blade 51).

[0073] Each auxiliary blade 51 can be individually rotated relative to the shaft assembly 30, particularly relative to the inner shaft 31, about a respective folding axis R51 between an unfolded orientation (shown in Figure 1 with reference numeral 51) and a folded orientation (shown in Figure 1 with reference numeral 51’). In other words, the auxiliary propeller 50 is foldable. Each folding axis R51 is perpendicular to the propeller axis X30 and the associated blade 51, and passes through the proximal end of the blade 51 by which the blade 51 is attached to the shaft assembly 30, particularly to the auxiliary hub 35. In the unfolded orientation, the blades 51 can be oriented radially with respect to the axis X30, while in the folded orientation, the blades 51 can be oriented parallel to the axis X30. In the folded orientation, the blades 51 preferably point in a direction opposite to the direction X1, i.e., the respective free ends of the blades 51 point in a direction opposite to the direction X1.

[0074] For example, Figure 1 the unfolded orientation shown with reference numeral 51 can be used in a forward mode or a backward mode, in which the blades 51 are radially oriented with respect to the axis X30 such that their front sides point in the direction X1.

[0075] For example, Figure 1 the folded orientation shown with reference numeral 51’ can be used in a towing mode, in which the blades 51 are subject to less drag along the axis X30.

[0076] Preferably, the folded orientation of the auxiliary blades 51 is adjustable, since each auxiliary blade 51 is configured to be positioned at at least one desired folded orientation between the unfolded orientation and the folded orientation. In the present example, the blades 51 rotate continuously from the unfolded orientation to the folded orientation such that the blades 51 can assume any desired folded orientation between the unfolded orientation and the folded orientation. In particular, the blades 51 can reach Figure 2 the intermediate orientation shown between the unfolded orientation and the folded orientation. The intermediate orientation can be considered a semi-folded or partially folded orientation, in which the drag of the blades 51 is reduced compared to the unfolded orientation, since the blades 51 are nearly parallel to the axis X30, or at least oriented between the radial orientation and the axial orientation. The intermediate orientation can be used in a power generation mode. In other examples, the folded orientation rather than the intermediate orientation is used in the power generation mode.

[0077] Preferably, the blades 41 are mechanically coupled to be in the same pitch orientation, i.e., they are synchronized with respect to their pitch orientation. Preferably, the blades 51 are mechanically coupled to be in the same folded orientation. That is, they are synchronized with respect to their folded orientation.

[0078] Preferably, the main blade 41 and the auxiliary blade 51 are mechanically coupled to each other via a mechanical coupling 60 such that the pitch orientation of the main blade 41 about the pitch axis R41 and the folding orientation of the auxiliary blade 51 about the folding axis R51 are dependent on each other, i.e., are synchronized. Preferably, by means of the mechanical coupling 60, when the auxiliary blade 51 is in the deployed orientation, the main blade 41 is in the forward drive pitch orientation, when the auxiliary blade 51 is in the intermediate orientation, the main blade 41 is in the feather pitch orientation, and when the auxiliary blade 51 is in the folded orientation, the main blade 41 is in the regeneration pitch orientation.

[0079] The slider 61 is configured to slide parallel to the axis X30. For this purpose, the slider is formed, for example, by a sleeve, mounted around the inner shaft 31 and inside the outer hub 32, and if implemented, inside the auxiliary hub 35. Preferably, the sleeve includes a main sleeve portion 65 in the auxiliary hub 35 and an auxiliary sleeve portion 66 around the protruding portion of the inner shaft 31. The portions 65 and 66 slide together along the axis X30, but are enabled to rotate relative to each other about the axis X30. When not sliding, the portion 66 rotates with the inner shaft 31 and the propeller 50 about the axis X30. When not sliding, the portion 65 rotates with the hub 32 and the propeller 40 about the axis X30. Preferably, the slider 61 includes an axial bearing 67 connecting the sleeve portion 65 to the sleeve portion 66.

[0080] The main mechanism 62 synchronizes the rotation of the blades 41 about their respective pitch axes R41 with the sliding of the slider 61 along the axis X30, in particular with the sliding of the sleeve portion 65. For this purpose, the main mechanism 62 can include a crankshaft actuated by the slider 61, as Figure 2 can be seen, and / or a rack and pinion system coupling the blades 41 to the slider 61.

[0081] The auxiliary mechanism 63 synchronizes the rotation of the blades 51 about their respective folding axes R51 with the sliding of the slider 61 along the axis X30, in particular with the sleeve portion 66. For this purpose, the auxiliary mechanism 63 can include a crankshaft and / or bevel gears coupling the blades 51 to the slider 61.

[0082] Thus, the orientation of the blades 41 about their pitch axes R41 is synchronized via the mechanisms 62 and 63 and via the slider with the orientation of the blades 51 about their folding axes R51.

[0083] In use, the blades 51 can be actuated to rotate about their axis R51 by centrifugal effects when the propeller 50 is rotating and by hydrodynamic forces when the propeller 50 is towed, without the need for a folding actuator. By centrifugal effects, the blades 51 tend to reach the deployed orientation. By towing in the direction X1, the hydrodynamic forces tend to fold the blades 51 back to the folded orientation because when in the folded orientation, the blades 51 are oriented opposite to the direction X1.

[0084] In use, the blades 41 can be actuated to rotate about their axis R41 by actuation of the blades 51 about their axis R51 via the mechanical coupling 60, without the need for a pitch actuator. Thus, no pitch or folding actuators are required.

[0085] In the forward drive mode in which the motor 5 actuates the shaft assembly 30 to rotate about the axis X30 and the brake 25 is released, the blades 51 are placed and maintained in the deployed orientation by centrifugal effects and thus the blades 41 are placed and maintained in the forward drive pitch orientation via the coupling 60.

[0086] In the tow mode in which the motor 5 does not actuate the shaft assembly 30, the brake 25 is released and the vessel 1 is propelled by other means (such as sails or other propellers), the blades 51 are placed in the intermediate orientation by hydrodynamic forces resulting from towing in the direction X1. Thus, the blades 51 place the blades 41 in the feathered pitch orientation via the coupling 60. The blades 41 are oriented in the feathered pitch orientation and they tend to prevent rotation of the propeller 40. The motor 5 is not actuated by the propeller because the propellers 40 and 50 are not rotating, or is actuated very slowly because the rotation of the propellers 40 and 50 is slowed down. Thus, no brake or only a weak brake is required to hold the rotor 7 in the tow mode.

[0087] In the power generation mode in which the motor 5 does not actuate the shaft assembly 30, the brake 25 is applied and the vessel 1 is propelled by other means (such as sails or other propellers), the blades 51 are placed in the folded orientation due to the absence of centrifugal effects (because they are prevented from rotating about the axis X30 by the brake) and due to hydrodynamic forces resulting from towing. Thus, the blades 51 place the blades 41 in the regenerative pitch orientation via the coupling 60 such that the propeller 40 rotates by hydrodynamic forces resulting from towing. The rotation of the propeller 40 drives the motor via the differential planetary gear 20, thereby generating electricity.

[0088] The terms used herein are for the purpose of describing particular aspects only and are not intended to limit the disclosure. As used herein, unless the context clearly dictates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms as well. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It should also be understood that when used herein, the terms "comprises" and / or "comprising" specify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0089] It should be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the disclosure, a first element may be termed a second element, and similarly, a second element may be termed a first element.

[0090] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe the relationship of one element to another, as shown in the figures. It should be understood that these terms, as well as those discussed above, are intended to cover different device orientations in addition to the orientation depicted in the figures. It should be understood that when an element is referred to as "connected" or "coupled" to another element, the element may be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as "directly connected" or "directly coupled" to another element, no intervening elements are present.

[0091] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It should also be understood that unless clearly defined herein, the terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense.

[0092] It should be understood that the disclosure is not limited to the aspects described above and shown in the figures; rather, those skilled in the art will recognize that many changes and modifications can be made within the scope of the disclosure and the appended claims. In the figures and the specification, the aspects have been disclosed for illustrative purposes only and not for purposes of limitation, and the scope of the inventive concept is set forth in the appended claims.

Claims

1. A propeller system (3) for a boat (1), comprising: - a shaft assembly (30) coaxial with a propeller axis (X30) of the propeller system (3); - a main propeller (40) including main blades (41) carried by the shaft assembly (30) and driven by the shaft assembly (30) to rotate about the propeller axis (X30), each main blade (41) being capable of rotating relative to the shaft assembly (30) between a first pitch orientation and a second pitch orientation about a respective pitch axis (R41) perpendicular to the propeller axis (X30) and extending along the main blade (41); and - an auxiliary propeller (50) including auxiliary blades (51) carried by the shaft assembly (30) and driven by the shaft assembly (30) to rotate about the propeller axis (X30), each auxiliary blade (51) being capable of rotating relative to the shaft assembly (30) between a deployed orientation and a folded orientation about a respective folding axis (R51) perpendicular to the propeller axis (X30) and the auxiliary blade (51).

2. The propeller system (3) according to claim 1, wherein the propeller system (3) includes a motor (5) operatively coupled to the shaft assembly (30) via a front shaft end (37) of the shaft assembly (30) to drive the main propeller (40) and the auxiliary propeller (50) to rotate about the propeller axis (X30) by driving the shaft assembly (30), wherein the main propeller (40) is positioned between the front shaft end (37) and the auxiliary propeller (50).

3. The propeller system (3) according to claim 2, wherein the motor (5) is an electric motor (5) configured to drive the shaft assembly (30) to rotate to propel the boat (1) and driven by the shaft assembly (30) to rotate to generate electricity.

4. The propeller system (3) according to any one of the preceding claims, wherein the pitch orientation of the main blade (41) is adjustable in that each main blade (41) is configured to be positioned at at least one desired pitch orientation between the first pitch orientation and the second pitch orientation.

5. The propeller system (3) according to any one of the preceding claims, wherein the main blade (41) can be oriented in a feather pitch orientation.

6. The propeller system (3) according to any one of the preceding claims, wherein the propeller system (3) includes a differential planetary gear (20) by means of which the electric motor (5) is operatively connected to the main propeller (40) and the auxiliary propeller (50).

7. The propeller system (3) according to claim 6, wherein the propeller system (3) comprises a brake (25) for immobilizing or at least braking the rotation of the auxiliary propeller (50) relative to the main propeller (40) about the propeller axis (X30) and / or for immobilizing or at least braking the rotation of the auxiliary propeller (50) relative to the stator (6) of the electric motor (5) or the hull (2) of the vessel (1) or the stern of the vessel (1) about the propeller axis (X30).

8. The propeller system (3) according to any one of the preceding claims, wherein the shaft assembly (30) comprises: - an outer hub (32) coaxial with the propeller axis (X30), the main propeller (40) being carried and driven by the outer hub (32); and - an inner shaft (31) coaxial with the propeller axis (X30), rotatably received in the outer hub (32), the auxiliary propeller (50) being carried and driven by the inner shaft (31).

9. The propeller system (3) according to any one of the preceding claims, wherein the main blade (41) and the auxiliary blade (51) are mechanically coupled to each other by a mechanical coupling (60) such that the orientation of the main blade (41) about the pitch axis (R41) and the orientation of the auxiliary blade (51) about the folding axis (R51) are dependent on each other.

10. The propeller system (3) according to any one of the preceding claims, wherein the shaft assembly (30) comprises an axial bearing (36) inserted between the main propeller (40) and the auxiliary propeller (50).

11. A vessel (1) comprising at least one propeller system (3) according to any one of the preceding claims.

12. The vessel (1) according to claim 11, wherein the vessel (1) is a sailing vessel.

13. The vessel (1) according to claim 11, wherein the vessel (1) is a motor vessel without sails.

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