MARINE CONTROLLABLE-PITCH PROPELLER, PROPELLER SYSTEM FOR A BOAT AND BOAT INCLUDING THE SAME

Abstract

A marine controllable-pitch propeller is mounted on a drive shaft. The marine controllable-pitch propeller has a propeller blade comprising an offset pitch interface, a pitch adjusting member that is adapted to be linearly movably mounted on the drive shaft and connected to the offset pitch interface, such that a linear motion of the pitch adjusting member along the drive shaft results in a pitch adjustment of the propeller blade, a rotary actuator, a linear actuator operationally arranged between the rotary actuator and the pitch adjusting member, and translation means for translating a rotary motion of the rotary actuator about the drive shaft into a linear motion of the linear actuator along the drive shaft. The pitch adjusting member is rotationally fixed to the propeller blade.

Claims

1. A marine controllable-pitch propeller to be mounted on a drive shaft, the marine controllable-pitch propeller comprising a propeller blade comprising an offset pitch interface, a pitch adjusting member that is adapted to be linearly movably mounted on the drive shaft and connected to the offset pitch interface such that a linear motion of the pitch adjusting member along the drive shaft results in a pitch adjustment of the propeller blade, a rotary actuator, a linear actuator operationally arranged between the rotary actuator and the pitch adjusting member, and translation means for translating a rotary motion of the rotary actuator about the drive shaft into a linear motion of the linear actuator along the drive shaft, wherein the pitch adjusting member is rotationally fixed to the propeller blade

2. The marine controllable-pitch propeller of claim 1, wherein the translation means is configured such the angular difference between end positions of the rotatory actuator is at least 90 degrees.

3. The marine controllable-pitch propeller of claim 1, wherein the translation means is configured such that the angular difference between end positions of the rotatory actuator is at least 180 degrees.

4. The marine controllable-pitch propeller of claim 1, wherein the translation means comprise thread means.

5. The marine controllable-pitch propeller of claim 1, wherein the translation means comprise an internal thread arranged on the rotary actuator and an external thread arranged on the linear actuator.

6. The marine controllable-pitch propeller of claim 5, wherein the linear actuator is arranged radially internally the rotary actuator.

7. The marine controllable-pitch propeller of claim 4, wherein the thread pitch of the thread means is selected such the angular difference between end positions of the rotatory actuator is at least 90 degrees.

8. The marine controllable-pitch propeller claim 1, wherein the offset pitch interface and the pitch adjusting member are configured to engage in a positive fit.

9. The marine controllable-pitch propeller of claim 1, wherein a bearing is arranged between the linear actuator and the pitch adjusting member.

10. The marine controllable-pitch propeller of claim 1, wherein the linear actuator and the pitch adjusting member are linearly fixed to one another.

11. The marine controllable-pitch propeller claim 1, wherein the linear actuator comprises a rotation blocking interface that is adapted to be engaged by a stationary member to rotationally fix the linear actuator.

12. The marine controllable-pitch propeller of claim 1 comprising a movable housing, which is rotationally fixed to the drive shaft, and a stationary housing, wherein the linear actuator is rotationally fixed to the stationary housing and the rotary actuator is rotatable with respect to the stationary housing for pitch adjustment of the propeller blade.

13. A propeller system comprising the marine controllable-pitch propeller of claim 1 as a front propeller and a counter-rotating secondary propeller as a rear propeller, the secondary propeller comprising secondary blades each being rotatable around a respective folding axis perpendicular to the drive shaft between a deployed orientation and a folded orientation.

14. A propeller system for a boat comprising: a shaft assembly, coaxial with a propeller axis of the propeller system, wherein the shaft assembly comprises the drive shaft; a primary propeller, comprising primary blades carried by the shaft assembly driven in rotation by the shaft assembly around the propeller axis, each primary blade being rotatable relative to the shaft assembly, around a respective pitch axis perpendicular to the propeller axis and extending along said primary blade, between a first pitch orientation and a second pitch orientation, wherein the primary propeller is a marine controllable-pitch propeller of claim 1; and a secondary propeller, comprising secondary blades carried by the shaft assembly, driven in rotation by the shaft assembly around the propeller axis, each secondary blade being rotatable relative to the shaft assembly, around a respective folding axis perpendicular to the propeller axis and to said secondary blade between a deployed orientation and a folded orientation.

15. The propeller system according to claim 14, wherein the propeller system comprises a motor, operatively coupled to the shaft assembly, via a front shaft end of the shaft assembly, for driving the primary propeller and the secondary propeller in rotation around the propeller axis, by driving the shaft assembly, wherein the primary propeller is positioned between the front shaft end and the secondary propeller.

16. The propeller system according to claim 15, wherein the motor is an electric motor configured to drive the shaft assembly in rotation for propelling the boat and to be driven in rotation by the shaft assembly for generating electrical power.

17. The propeller system according to claim 14, wherein the primary blades may be oriented to a feathering pitch orientation.

18. The propeller system according to claim 14, wherein the propeller system comprises a differential planetary gear by means of which the electrical motor is operatively connected to the primary propeller and to the secondary propeller.

19. The propeller system according to claim 18, wherein the propeller system comprises a brake for immobilizing or at least braking the secondary propeller relative to the primary propeller in rotation around the propeller axis and/or for immobilizing or at least braking the secondary propeller in rotation around the propeller axis relative to a stator of the electric motor or to a hull of the boat or to a stern of the boat.

20. The propeller system according to claim 14, wherein the shaft assembly comprises: an outer hub, coaxial with the propeller axis the primary propeller being carried and driven by the outer hub; and an inner shaft, coaxial with the propeller axis rotatably received in the outer hub the secondary propeller being carried and driven by the inner shaft.

21. The propeller system according to claim 14, wherein the primary blades and the secondary blades are mechanically coupled to each other by a mechanical coupling so that the orientation of the primary blades around the pitch axes and the orientation of the secondary blades around the folding axes are dependent from each other.

22. The propeller system according to claim 14, wherein the shaft assembly comprises an axial bearing interposed between the primary propeller and the secondary propeller.

23. A boat including at least one propeller system according to claim 14.

24. The boat according to claim 23, wherein the boat is a sailboat.

25. The boat according to claim 23, wherein the boat is a motor boat devoid of sail.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The above, as well as additional objects, features and advantages, will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments, wherein

[0064] FIG. 1 is an isometric view of a marine controllable-pitch propeller,

[0065] FIG. 2 is an axial cross-section through the marine controllable-pitch propeller of FIG. 1,

[0066] FIG. 3 is an exemplary schematic view of a boat including a propeller system according to one example, and

[0067] FIG. 4 is a longitudinal section view of a part of the propeller system of FIG. 3.

DETAILED DESCRIPTION

[0068] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness. Like reference characters refer to like elements throughout the description.

[0069] FIGS. 1 and 2 illustrate an example marine controllable-pitch propeller 1 (hereinafter propeller). The propeller 1 is mounted on a drive shaft d, the ultimate end of which is shown in FIGS. 1 and 2. The propeller 1 typically comprises two to six propeller blades, one propeller blade 10 being illustrated herein. As is shown in FIG. 1, the propeller blade 10 comprises an offset pitch interface 11.

[0070] The propeller 1 further comprises a pitch adjusting member 20, a rotary actuator 30, a linear actuator 40 and translation means 31, 41.

[0071] The offset pitch interface 11 (not shown in FIG. 2) is in this embodiment a protruding member that extends parallel to and at a distance from a pitch axis of the propeller blade. The protruding member is embodied as a pin. The pin is of circular cross-section.

[0072] The pitch adjusting member 20 is adapted to be linearly movably mounted on the drive shaft d. In other words, the pitch adjusting member 20 may be free to slide axially along the drive shaft d. The present pitch adjusting member 20 comprises a through-opening of circular cross-section through which the drive shaft d passes. The pitch adjusting member 20 is preferably not rotationally fixed directly to the drive shaft d, such that the pitch adjusting member 20 may easily slide along the drive shaft d.

[0073] As is apprehended from FIG. 1, a linear motion A (along the drive shaft d, as indicated in FIG. 1) of the pitch adjusting member 20 results in a pitch adjustment of the propeller blade 10. This because the pitch adjusting member 20 is connected to the offset pitch interface 11. Similarly, in U.S. Pat. No. 3,567,340A a linear motion of the bearing ring (item 20) results in a rotation of the propeller blades (item 11). A pitch adjustment P of the propeller blade 10 corresponds to a rotation (as indicated in FIG. 1) of the propeller blade 10 around its pitch axis. The pitch axis extends longitudinally and centrally through the propeller blade 10.

[0074] The pitch adjusting member 20 is rotationally fixed to the propeller blade 10. In the present embodiment, the pitch adjusting member 20 comprises a receiving opening 21 that is adapted to receive the protruding member (offset pitch interface 11). The receiving opening is embodied as a recess in an outer surface of the pitch adjusting member 20. The receiving opening 21 may e.g. be of circular or square cross-section.

[0075] As is illustrated, the propeller blade 10 is rotationally journalled and when the pitch adjusting member 20 is moved axially A along the drive shaft d, the offset pitch interface 11 is moved with respect to the pitch axis of the propeller blade 10. The propeller blade 10 is thereby forced to rotate or pivot P around its pitch axis as the offset pitch interface 11 is distanced from the pitch axis.

[0076] The pitch adjusting member 20 may comprise a first portion 22, a second portion 23 and a third portion 24. The first portion 22 may, as is illustrated, extend into the linear actuator 40. The first portion 22 may be sleeve-shaped. The second, or central, portion 23 may comprise the receiving opening(s) 21 and may be essentially box-shaped. In more detail, the second portion 23 may comprise a number (here four) of side faces wherein some (here two) or all comprise receiving openings 21. The third portion 24 may be disc-shaped and may have a larger radial extension than the first 22 and second 23 portions.

[0077] The linear actuator 40 is arranged to linearly move the pitch adjusting member 20, in other words axially move the latter along the drive shaft d. The linear actuator is embodied as a hollow circular cylinder. As is described below, the cylinder may comprise external threads 41. The linear actuator 40 is adapted to be linearly movably mounted on the drive shaft d. The present linear actuator 40 comprises a through-opening of circular cross-section through which the drive shaft d passes. The linear actuator 40 is not rotationally fixed to the drive shaft d.

[0078] In the present embodiment, the linear actuator 40 is arranged adjacent the pitch adjusting member 20 and may push the latter in one axial direction along the drive shaft d. Referring in particular to FIG. 2, the linear actuator 40 may push the pitch adjusting member 20 towards the propeller blade 10, i.e. to the right in FIG. 2. The linear actuator 40 may be arranged directly adjacent the pitch adjusting member 20, or there may be a bearing (not shown) between the linear actuator 40 and the pitch adjusting member 20.

[0079] The rotary actuator 30 is controllable, more precisely rotatable R (as indicated in FIG. 1), to adjust the pitch of the propeller blade 10. The rotary actuator 30 may be referred to as an input actuator. The rotary actuator 30 may, as is disclosed, comprise a control interface 32, or control input interface, that may be configured to interact with an external control device. Preferably, the control interface 32 is adapted for forming a positive fit with the external control device. The control interface 32 may, as shown, be embodied as teeth on the outer surface of the rotary actuator 30. The teeth 32 may be engaged by a chain (not shown) or a gear (not shown) forming part of the external control device. Alternatively, a belt connection or another connection may be provided between the external control device and the rotary actuator 30, and the latter may be configured accordingly.

[0080] The present linear actuator 40 comprises a rotation blocking interface 43 that is engaged by at least one stationary member (not shown) to rotationally fix the linear actuator 40. The rotation blocking interface 43 is in the present case a recess (see FIG. 2) in the radially outer surface of the linear actuator 40. In other embodiments, the rotation blocking interface 43 may be one or more through-holes made in the linear actuator 40, each engaged by a stationary member. The stationary member may be fixed to the stationary housing 3 (described below).

[0081] The stationary member may extend through the rotary actuator 30 and in parallel with the drive shaft d and through the recess 43 (or through-hole). Thus, the rotary actuator 30 need not comprise a closed outer side wall (left in the figures) but may be at least partly open such that the stationary member may extend there through.

[0082] The translation means 31, 41 are configured to translate, in other words or convert or transform, a rotary motion of the rotary actuator 30 into a linear motion of the linear actuator 40. In the present embodiment, the translation means comprise thread means. The thread pitch may be selected such the angular difference between end positions of the rotatory actuator 30 is at least 90 degrees, at least 180 degrees, or such that the rotary actuator 30 may be rotated several turns between its end positions.

[0083] The translation means 31, 41 is here embodied as an integral part of the rotary actuator 30 and the linear actuator 40. As is illustrated in FIG. 2, the rotary actuator 30 may comprise an internal thread 31 that that cooperates with an external thread 41 on the linear actuator 40.

[0084] The present propeller 1 comprises a movable housing 2 and a stationary housing 3 (only partly and schematically illustrated). The movable housing 2 is rotationally fixed to the drive shaft d. In the present example, the movable housing 2 is fixed, i.e. rotationally fixed, to the drive shaft d at the right hand end of the movable housing 2. When the propeller blade(s) 10 is rotated by the drive shaft d, the movable housing 2 rotates with the drive shaft d whereas the stationary housing 3 does not. The rotary motion is in the present embodiment transferred from the drive shaft d to the movable housing 2, and then via the propeller blade 10 to the pitch adjusting member 20.

[0085] Next, a use or operation of the propeller 1 will be described. When an operator or a control system of a marine vehicle demands a pitch adjustment of the propeller blade(s) 10, the rotary actuator 30 is rotated (for example by the external control device). Before being brought to rotate, the rotary actuator 30 is stationary. The rotary actuator 30 may for example be attached to the stationary housing 3. Hence, the rotary actuator 30 is not rotationally fixed to the drive shaft d. During pitch adjustment, the rotary actuator 30 may be rotated with respect to the stationary housing 3. During pitch adjustment, the rotary actuator 30 is rotated with respect to the linear actuator 40.

[0086] The rotation of the rotary actuator 30 with respect to the linear actuator 40 is translated into a linear (right) movement of the linear actuator 40, by means of the respective threads 31, 41 described above. The linear actuator 40 is brought to move linearly along the drive shaft d. The linear actuator 40 does not rotate, as has been describe above (stationary member and rotation blocking interface 43). The linear actuator 40 may be enclosed within the rotary actuator 30 as the linear actuator 40 travels axially inside the rotary actuator 30.

[0087] The linear movement of the linear actuator 40 causes the pitch adjusting member 20 move linearly (to the right) along the drive shaft d. The movement of the linear actuator 40 along the drive shaft d rotates the propeller blade(s) 10 such that the pitch is adjusted, as has been described. The blade pitch may be controlled in idle condition, when the drive shaft d brings the blades 10 to rotate, and when the blades 10 bring the drive shaft d to rotate.

[0088] When the pitch of the propeller blade(s) 10 is to be adjusted in the opposite direction, the pitch adjusting member 20 is moved linearly (to the left) along the drive shaft d in the opposite direction. The pitch adjusting member 20 may be moved in both directions by the rotary actuator 30 being rotated, or spring means (not shown) may be arranged to push the pitch adjusting member 20 towards the linear actuator 40 for the return movement. For example, a compression spring may be positioned between the pitch adjusting member 20 and the movable housing 2. More precisely, the compression spring may be positioned between the third portion 24 of the pitch adjusting member 20 and a surface of the movable housing 2 that faces the third portion 24. Such possible spring location 25 is indicated in FIG. 2.

[0089] FIG. 3 shows, in a schematic manner, a hull 102 of a boat 100, equipped with a propeller system 103, which is a duo propeller system. The boat 100 may be a sailboat, or a motor boat devoid of sail. In the present example, the propeller system 103 may comprise: an electric motor 105 with a stator 106 and a rotor 107; a differential planetary gear 120, with a sun gear 121, a planetary carrier 122 and a ring 123; a brake 125; a shaft assembly 130, with an inner shaft 131, an outer hub 132 and an axial bearing 136; a primary propeller 140, with primary blades 141; a secondary propeller 150 with secondary blades 151; a mechanical coupling 160, with a slider 161, a primary mechanism 162 and a secondary mechanism 163. However, some of these components may be omitted, modified or replaced.

[0090] The illustrated example concerns a straight shaft propeller system. However, the propeller system may be implemented for other types of drive systems, such as a stern-drive drive system or an outboard drive system.

[0091] FIG. 4 shows, in a more detailed manner, the shaft assembly 130, with the inner shaft 131, the outer hub 132 and the axial bearing 136; the primary propeller 140, with the primary blades 141; the secondary propeller 150 with the secondary blades 151; the mechanical coupling 160, with the slider 161, the primary mechanism 162 and the secondary mechanism 163.

[0092] As explained below, the propeller system 103 is configured to be operated in a forward mode, in a dragging mode and in a power generation mode. In FIG. 3, the boat 100 floats in water 109.

[0093] In the illustrated example, the propeller system 103 defines propeller axis X130, fixed relative to the stator 106 and/or the hull 102 and to which the shaft assembly 130 and the propellers 140 and 150 are coaxial. The propeller axis X130 may be horizontal or slightly inclined when the boat 100 is in use in water 109, as in FIG. 3.

[0094] In case of a stern drive, the axis X130 may be fixed relative to the stern instead of the hull. In case of an outboard drive, the axis X130 may be fixed relative to the outboard motor casing instead of the hull.

[0095] The boat 100 defines a forward direction X100, oriented from the stern to the bow.

[0096] In the illustrated example, the stator 106 of the motor 105 is attached to the hull 102 of the boat 100. The rotor 107 may be coaxial with axis X130, as shown, and operatively connected to the shaft assembly 130, here via the differential planetary gear 120, or may be positioned otherwise, and operatively connected to the shaft assembly via additional angled gears (not shown), which connect said rotor 107 to the differential planetary gear 120.

[0097] In the case of a stern-drive system, the stator 106 may be attached to a stern instead of being attached to the hull.

[0098] In the case of an outboard system, the stator 106 may be attached to an outboard motor casing instead of the hull.

[0099] The rotor 107 may be driven in rotation relative to the stator 106 under electromagnetic interaction between the rotor 107 and the stator 106 when the motor 105 is electrically powered. The rotor 107 may also be driven in rotation by the shaft assembly 130, as explained below, so that the rotation of the rotor 107 relative to the stator 106 generates electrical power for the boat 100, by electromagnetic interaction in the motor 105.

[0100] In the illustrated example, the rotation of the rotor 107 is operated about axis X130, but could be operated around a different rotor axis, depending on the configuration of the motor relative to the shaft assembly 130.

[0101] In the present example, the outer hub 132 and the inner shaft 131 of the shaft assembly 130 is coaxial with the propeller axis X130. The inner shaft 131 is received in the outer hub 132, i.e. may rotate relative to the outer hub 132 and to the stator 106, about axis X130. The outer hub 132 may also rotate relative to the inner shaft 131 and to the stator 106 about the axis X130.

[0102] In the example, the primary propeller 140 is arranged frontwards, i.e. in the direction X100 relative to the secondary propeller 150. The propeller 140 is a front propeller and the propeller 150 is a rear propeller.

[0103] The primary propeller 140 is attached to the outer hub 132, so that the outer hub 132 carries the primary propeller 140, and may drive the propeller 140 in rotation around the axis X130, when the shaft assembly 130 is driven by the motor 105. The propeller 140 may also drive the outer hub 132 in rotation about the axis X130, in dragging mode and in power generation mode.

[0104] The secondary propeller 150 is attached to the inner shaft 131, so that the inner shaft 131 carries the secondary propeller 150, and may drive the propeller 150 in rotation around the axis X130, when the shaft assembly 130 is driven by the motor 105. The propeller 150 may also drive the inner shaft 131 in rotation about the axis X130, in dragging mode. For carrying the propeller 150, the inner shaft 131 may protrude from the outer hub 132 in a direction opposite to direction X100. The secondary propeller 150 is preferably attached to the protruding part of the inner shaft 131. To this end, the shaft assembly preferably comprises a secondary hub 135, fixedly attached to the shaft 131, at the protruding part thereof. The secondary hub 135 is arranged adjacent to the outer hub 132, along axis X130. The outer hub 132 is positioned in direction X100 relative to the secondary hub 135.

[0105] In the illustrated example, the axial bearing 136 is interposed between the propellers 140 and 150, parallel to the axis X130. As shown in FIG. 3 and FIG. 4, the axial bearing 136 may be positioned around the inner shaft 131, and axially bear against the outer hub 132 and the secondary hub 135.

[0106] The shaft assembly 130 is connected to the rotor 107 via the differential planetary gear 120, so that the motor 105 may drive the shaft assembly 130 in rotation for propelling the boat 100 in the forward mode via the differential planetary gear 120, or may be driven in rotation by the shaft assembly 130 in power generation mode via the differential planetary gear 120, the motor 105 thereby generating electrical power. Preferably, the differential planetary gear 120 is coaxial with axis X130, i.e. the sun gear 121, the planetary carrier 122 and the ring 123 are coaxial with axis X130 and may rotate relative to axis X130. In the present example, the sun gear 121 is fixedly attached to the rotor 107, the planetary carrier 122 is fixedly attached the inner shaft 131 of the shaft assembly 130 and the ring 123 is fixedly attached to the outer hub 132 of the shaft assembly 130. In particular, the carrier 122 is fixedly attached to a front shaft end 137 of the shaft 131, the front shaft end 137 being opposite to the protruding part of the shaft 131 along axis X31. In a manner known per se, the carrier 122 carries one or more planet gears 24 which are rotatable around a respective planet axis relative to the carrier 122, each planet axis being parallel to the axis X130 and fixed relative to the carrier 122, the planet gears 24 being meshed, inwardly, with the sun gear 121, and, outwardly, with the ring 123. To this end, the sun gear 121 has teeth oriented outwardly, and the ring 123 has teeth oriented inwardly.

[0107] The differential planetary gear 120 adaptively and automatically distributes the torque imparted by the rotor 107, between the propeller 140, via the outer hub 132, and to the propeller 150, via the inner shaft 131, depending on the hydrodynamic efforts that may oppose to the rotation of the propellers 140 and 150 around the axis X130. In other words, a first portion of the torque generated at the rotor 107 is transmitted to the propeller 140 and a second portion is transmitted to the propeller 150, and the ratio between the first portion and the second portion may vary depending on the ratio of the efforts respectively opposing the rotation of the propellers 140 and 150. In other words, the differential planetary gear 120 automatically and adaptively balances the ratio of the respective torques produced by the propellers 140 and 150, when the motor 105 powers the rotation of the rotor 107. More precisely, the differential planetary gear 120 adaptively changes the rotation speed of the propellers to fulfill a torque ratio between the propellers 140 and 150, the ratio depending on the design of the planetary gear 120 (in particular, depending on the respective number of teeth for the sun gear 121, planetary gears 24 and ring 123).

[0108] In the event one of the propellers 140 and 150 is completely prevented from rotating around axis X130, then the other of the propellers 140 and 150 may rotate and benefit from all the torque imparted by the motor 105, through the differential planetary gear 120. The differential planetary gear 120 is mechanically reversible, which means that if one of the propellers, such as the propeller 140, is rotated, the torque is distributed to the motor 105 and to the other propeller, for example the propeller 150, via the differential planetary gear 120. If the propeller 150 is prevented from rotating and the propeller 140 is rotated, then all the torque of the propeller 140 is transmitted to the motor 105 via the differential planetary gear 120.

[0109] The brake 125 is configured for, when applied, immobilizing or at least braking the secondary propeller 150, in rotation around the propeller axis X130 relative to the stator 106. For the illustrated case where the stator 106 is fixed relative to the hull 102, the propeller 150 is immobilized or at least slowed in rotation about axis X130 relative to the hull 102. In other cases where the stator 106 is mobile relative to the hull 102 (such as, for outboard drive systems), the propeller 150 is immobilized or at least slowed in rotation about axis X130 relative to the stator 106. In other cases where the axis X130 is mobile relative to the stator 106 and the hull 102 (such as, for stern drive systems), the propeller 150 is immobilized in rotation around axis X130 relative to the stern. When released, the rotation of the propeller 150 around axis X130 relative to the stator 106 is enabled. The brake 125 may comprise a slider, which may slide along axis X130, between a release position shown in FIG. 3, and an applied position where the brake 125 is coupled with the carrier 122, or applies braking pressure to the carrier, thus preventing the carrier 122 to rotate, in that the carrier 122 is fixed relative to the hull 102 via the brake 125.

[0110] In this case, when the brake 125 is applied, the torque generated by the motor 105 is entirely transmitted to the propeller 140 through the differential planetary gear 120, while the propeller 150 does not rotate. When the brake 125 is applied, a rotation of the propeller 140, obtained by hydrodynamic forces applied to the propeller, is entirely transmitted to the motor 105 via the differential planetary gear 120 while the propeller 150 does not rotate.

[0111] Alternatively or additionally, a brake may immobilize or at least brake the propellers 140 and 150 in rotation around the axis X130, so that the propellers 140 and 150 always rotate at the same rotation speed around the axis X130 relative to the hull 102, when the brake is applied. In this case, the brake synchronizes the rotation of the propellers 140 and 150.

[0112] Since the carrier 122 is attached to the shaft 131 at the front shaft end 137 thereof and since the ring 123 is connected to the outer hub 132, the motor 105 is coupled to the shaft assembly 130 via the front shaft 137 end and the outer hub 132 for driving the propellers 140 and 150 in rotation around the axis X130. Since the propeller 140 is a front propeller and the propeller 150 is a rear propeller, the primary propeller 140 is positioned between the front shaft end 137 and the secondary propeller 150, and between the differential planetary gear 120 and the secondary propeller 150.

[0113] Each primary blade 141 is carried by the shaft assembly 130, in particular by the outer hub 132, so as to rotate together with the outer hub 132 around axis X130. Each blade 141 is oriented radially relative to the axis X130. Preferably, the primary blades 141 are equally distributed around the axis X130. A number of primary blades 141 such as two, three, four or more primary blades 141 may be provided. Each primary blade 41 has a helical profile, i.e. is cambered, so that the blades 141 generate a propelling force directed parallel to the axis X130 when the propeller 140, and thus the blades 141, are rotated by the motor 105 through the shaft assembly 130, in particular through the outer hub 132. Thanks to their helical profile, each blade 41 may also be driven in rotation by the water 109, i.e. by hydrodynamic forces applied to the blades 141, when the propeller 140 is dragged in the water 109 along the axis X130. In this case, the propeller 140 may actuate the rotation of the rotor 107 through the differential planetary gear 120, provided the brake 125 is applied and prevents, or reduces, the rotation of the propeller 150.

[0114] Each primary blade 141 is individually rotatable relative to the shaft assembly 130, in particular to the outer hub 132, around a respective pitch axis R141, between a first pitch orientation and a second pitch orientation. In other words, the primary propeller 140 is of variable pitch. Each pitch axis R141 is perpendicular to the propeller axis X130, preferably radial to the propeller axis X130, and extends along the concerned blade 41, as shown in FIG. 3 and FIG. 4.

[0115] For example, the first pitch orientation is a regeneration pitch orientation, which may be used in power generation mode or in a backward mode. In the regeneration pitch orientation, the primary blades 141 are oriented with a front side thereof directed opposite to direction X100. In the power generation mode, the regeneration pitch orientation is most appropriate for the propeller 140 for being rotated by hydrodynamic forces when dragged as the boat 100 moves in direction X100. In the backward mode, the regeneration pitch orientation is most appropriate for propelling the boat backwards, i.e. opposite to direction X100.

[0116] For example, the second pitch orientation, shown in FIG. 3, is a forward drive pitch orientation, that may be used in forward mode, where the blades 141 are oriented with their front side directed in direction X100, most appropriate for propelling the boat in the direction X100.

[0117] Preferably, the pitch orientation of the primary blades 141 is adjustable, in that each primary blade 141 is configured to be positioned in at least one desired pitch orientation between the first pitch orientation and the second pitch orientation. In the present example, the blades 141 continuously rotate from the first to the second pitch orientation, so that any desired pitch orientation between the first and second pitch orientations may be adopted by the blades 141. In particular, the blades 141 may reach a feather pitch orientation, shown in FIG. 4, between the first and second pitch orientations. In the feather pitch orientation, each blade 141 is oriented so that their sides are substantially parallel to the axis X130, i.e. oriented sideways, so that the drag of the blades 141 parallel to axis X130 is reduced. When the blades 141 are in feather pitch orientation, their drag is maximal in an orthoradial direction, i.e. in a rotational direction around axis X130, thereby tending to prevent the propeller 140 from rotating around axis X130 due to rotational hydrodynamic forces.

[0118] Each secondary blade 151 is carried by the shaft assembly 130, in particular by the inner shaft 131, via the secondary hub 135, so as to rotate together with the inner shaft 131 around axis X130. Preferably, the secondary blades 151 are equally distributed around the axis X130. A number of secondary blades 151 such as two, three, four or more secondary blades 151 may be provided. Each secondary blade 151 has a helical profile, i.e. is cambered, so that the blades 151 generate a propelling force directed parallel to the axis X130 when the propeller 150, and thus the blades 151, are rotated by the motor 105 through the shaft assembly 130, in particular through the inner shaft 131. Thanks to their helical profile, each blade 151 may also be driven in rotation by the water 109, i.e. by hydrodynamic forces applied to the blades 151, when the propeller 150 is dragged in the water 109 along the axis X130.

[0119] Each secondary blade 151 is individually rotatable relative to the shaft assembly 130, in particular to the inner shaft 131, around a respective folding axis R151, between a deployed orientation, shown in FIG. 3 at references 151, and a folded orientation, shown in FIG. 3 at references 151. In other words, the secondary propeller 150 is foldable. Each folding axis R151 is perpendicular to the propeller axis X130 and to the concerned blade 151, and crosses through a proximal end of the blade 151 by which the blade 151 is attached to the shaft assembly 130, in particular to the secondary hub 135. In the deployed orientation, the blades 151 may be oriented radially to the axis X130, whereas in the folded orientation, the blades 151 may be oriented parallel to the axis X130. In folded orientation, the blades 151 are preferably directed opposite to the direction X100, i.e. a respective free end of the blades 151 is directed opposite to the direction X100.

[0120] For example, the deployed orientation, shown in FIG. 3 at references 151, may be used in forward mode or in backward mode, where the blades 151 are oriented radially relative to the axis X130 with their front side directed in direction X100.

[0121] For example, the folded orientation, shown in FIG. 3 at references 151, may be used in dragging mode, where the blades 151 are less subject to drag along axis X130.

[0122] Preferably, the folding orientation of the secondary blades 151 is adjustable, in that each secondary blade 151 is configured to be positioned in at least one desired folding orientation between the deployed orientation and the folded orientation. In the present example, the blades 151 continuously rotate from the deployed to the folded orientation, so that any desired folding orientation between the deployed and folded orientations may be adopted by the blades 151. In particular, the blades 151 may reach an intermediate orientation, shown in FIG. 4, between the deployed and the folded orientations. The intermediate orientation may be considered as a half-folded or partially-folded orientation, where the drag of the blades 151 is reduced compared to the deployed orientation, as the blades 151 are almost parallel to the axis X130, or at least are oriented between a radial and an axial orientations. The intermediate orientation may be used in the power generation mode. In other examples, the folded orientation used in power generation mode, instead of the intermediate orientation.

[0123] Preferably, the blades 141 are mechanically coupled for being at the same pitch orientation, i.e. are synchronized for their pitch orientation. Preferably, the blades 151 are mechanically coupled for being at the same folding orientation, i.e. are synchronized for their folding orientation.

[0124] Preferably, the primary blades 141 and the secondary blades 151 are mechanically coupled to each other via the mechanical coupling 160, so that the pitch orientation of the primary blades 141 around the pitch axes R141 and the folding orientation of the secondary blades 151 around the folding axes R151 are dependent from each other, i.e. are synchronized. Preferably, by means of the mechanical coupling 160, the primary blades 141 are in the forward drive pitch orientation when the secondary blades 151 are in the deployed orientation, the primary blades 141 are in the feathering pitch orientation when the secondary blades 151 are in the intermediate orientation, and the primary blades 141 are in the regeneration pitch orientation when the secondary blades 151 are in the folded orientation.

[0125] The slider 161 is configured for sliding parallel to axis X130. To this end, the slider is for example formed by a sleeve, mounted around the inner shaft 131 and inside the outer hub 132, and, if implemented, inside the secondary hub 135. Preferably, said sleeve comprises a primary sleeve part 165, in the secondary hub 135, and a secondary sleeve part 166 around the protruding part of the inner shaft 131. The parts 165 and 166 slide together along the axis X130, but are enabled to rotate relative to each other around axis X130. When not sliding, the part 166 rotates with the inner shaft 131 and the propeller 150 around the axis X130. When not sliding, the part 165 rotates with the hub 132 and the propeller 140 around the axis X130.

[0126] Preferably, the slider 161 comprises an axial bearing 167 connecting the sleeve part 165 to the sleeve part 166.

[0127] The primary mechanism 162 synchronizes the rotation of the blades 141 around their respective pitch axes R141 with the sliding of the slider 161 along axis X130, in particular with the sliding of the sleeve part 165. To that end, the primary mechanism 162 may comprise crankshafts actuated by the slider 161, as visible in FIG. 4 and/or a rack and pinion system, coupling the blades 141 to the slider 161.

[0128] The secondary mechanism 163 synchronizes the rotation of the blades 151 around their respective folding axes R151 with the sliding of the slider 161 along axis X130, in particular with the sleeve part 166. To that end, the secondary mechanism 163 may comprise crankshafts and/or conical gears, coupling the blades 151 with the slider 161.

[0129] Thus, the orientation of the blades 141 around their pitch axes R141 is synchronized with the orientation of the blades 151 around their folding axes R151, via the mechanisms 162 and 163 and via the slider.

[0130] In use, the blades 151 may be actuated in rotation about their axes R151, without the need of a folding actuator, by centrifugal effect, when the propeller 150 rotates, and by hydrodynamic forces, when the propeller 150 is dragged. By centrifugal effect, the blades 151 tend to reach the deployed orientation. By dragging in the direction X100, the hydrodynamic forces tend to fold the blades 151 back to the folded orientation, since the blades 151 are oriented opposite to the direction X100 when in the folded orientation.

[0131] In use, the blades 141 may be actuated in rotation about their axes R141, without the need of a pitching actuator, by actuation of the blades 151 about their axes R151, via the mechanical coupling 160. Thus, no pitch or folding actor is necessary.

[0132] In the forward drive mode, where the motor 105 actuates the shaft assembly 130 in rotation about the axis X130 and the brake 125 is released, the blades 151 are put and maintained to deployed orientation by centrifugal effect, and thus put and maintain the blades 141 in forward drive pitch orientation via the coupling 160.

[0133] In dragging mode, where the motor 105 does not actuate the shaft assembly 130, the brake 125 is released and the boat 100 is propelled by other means, such as sails or other propellers, the blades 151 are put to an intermediate orientation by the hydrodynamic forces caused by the dragging in direction X100. Thus, the blades 151 put the blades 141 in feathering pitch orientation via the coupling 160. The blades 141 being oriented in feathering pitch orientation, they tend to prevent rotation of the propeller 140. The motor 105 is not actuated by the propellers 140 and 150 since they do not rotate, or is actuated very slowly since the rotation of the propeller 140 and 150 is slow. Thus, no brake, or only a weaker brake, is required for immobilizing the rotor 107 in dragging mode.

[0134] In power generation mode, where the motor 105 does not actuate the shaft assembly 130, the brake 125 is applied and the boat 100 is propelled by other means, such as sails or other propellers, the blades 151 are put to a folded orientation, due to the absence of centrifugal effect since they are prevented from rotating about the axis X130 by the brake, and due to hydrodynamic forces caused by dragging. Thus, the blades 151 put the blades 141 in regeneration pitch orientation via the coupling 160, so that the propeller 140 is rotated by the hydrodynamic forces caused by the dragging. The rotation of the propeller 140 drives the motor through the differential planetary gear 120, thereby producing electrical power.

[0135] The primary propeller 140 described with reference to FIGS. 3 and 4 may be a marine controllable-pitch propeller 1 described with reference to FIGS. 1 and 2. The pitch adjusting member 20 may be connected to, or formed in one piece with, the slider 161. The pitch adjusting member 20 described with reference to FIGS. 1 and 2 may be connected to the primary sleeve part 165 described with reference to FIGS. 3 and 4. Thus, a linear movement, or sliding, of the pitch adjusting member 20 may cause a linear movement of the primary sleeve part 165 and vice versa.

[0136] Also disclosed are examples according to the following clauses:

[0137] Clause 1. A marine controllable-pitch propeller (1) to be mounted on a drive shaft (d), the marine controllable-pitch propeller (1) comprising [0138] a propeller blade (10) comprising an offset pitch interface (11), [0139] a pitch adjusting member (20) that is adapted to be linearly movably mounted on the drive shaft (d) and connected to the offset pitch interface (11), such that a linear motion (A) of the pitch adjusting member (20) along the drive shaft (d) results in a pitch adjustment (P) of the propeller blade (10), [0140] a rotary actuator (30), [0141] a linear actuator (40) operationally arranged between the rotary actuator (30) and the pitch adjusting member (20), and [0142] translation means (31, 41) for translating a rotary motion (R) of the rotary actuator (30) about the drive shaft (d) into a linear motion (A) of the linear actuator (40) along the drive shaft (d), wherein the pitch adjusting member (20) is rotationally fixed to the propeller blade (10).

[0143] Clause 2. The marine controllable-pitch propeller (1) of clause 1, wherein the translation means (31, 41) is configured such the angular difference between end positions of the rotatory actuator (30) is at least 90 degrees.

[0144] Clause 3. The marine controllable-pitch propeller (1) of clause 1, wherein the translation means (31, 41) is configured such that the angular difference between end positions of the rotatory actuator (30) is at least 180 degrees.

[0145] Clause 4. The marine controllable-pitch propeller (1) of any preceding clause, wherein the translation means (31, 41) comprise thread means.

[0146] Clause 5. The marine controllable-pitch propeller (1) of any preceding clause, wherein the translation means (31, 41) comprise an internal thread (31) arranged on the rotary actuator (30) and an external thread (41) arranged on the linear actuator (40).

[0147] Clause 6. The marine controllable-pitch propeller (1) of clause 5, wherein the linear actuator (40) is arranged radially internally the rotary actuator (30).

[0148] Clause 7. The marine controllable-pitch propeller (1) of any one of clauses 4 to 6, wherein the thread pitch of the thread means is selected such the angular difference between end positions of the rotatory actuator (30) is at least 90 degrees.

[0149] Clause 8. The marine controllable-pitch propeller (1) of any preceding clause, wherein the offset pitch interface (11) and the pitch adjusting member (20) are configured to engage in a positive fit.

[0150] Clause 9. The marine controllable-pitch propeller (1) of any preceding clause, wherein the offset pitch interface (11) comprises a protruding member that extends parallel to and at a distance from a pitch axis of the propeller blade (10).

[0151] Clause 10. The marine controllable-pitch propeller (1) of clause 9, wherein the pitch adjusting member (20) comprises a receiving opening (21) that is adapted to receive the protruding member.

[0152] Clause 11. The marine controllable-pitch propeller (1) of clause 10, wherein the pitch adjusting member (20) comprises a number of separate receiving openings (21).

[0153] Clause 12. The marine controllable-pitch propeller (1) of any preceding clause, wherein a bearing is arranged between the linear actuator (40) and the pitch adjusting member (20).

[0154] Clause 13. The marine controllable-pitch propeller (1) of any preceding clause, wherein the linear actuator (40) and the pitch adjusting member (20) are linearly fixed to one another.

[0155] Clause 14. The marine controllable-pitch propeller (1) of any preceding clause, wherein the linear actuator (40) comprises a rotation blocking interface (43) that is adapted to be engaged by a stationary member to rotationally fix the linear actuator (40).

[0156] Clause 15. The marine controllable-pitch propeller (1) of any preceding clause comprising a movable housing (2), which is rotationally fixed to the drive shaft (d), and a stationary housing (3), wherein the linear actuator (40) is rotationally fixed to the stationary housing (3) and the rotary actuator (30) is rotatable with respect to the stationary housing (3) for pitch adjustment of the propeller blade (10).

[0157] Clause 16. The marine controllable-pitch propeller (1) of any preceding clause configured such that the pitch adjusting member (20) rotates together with the propeller blade (10).

[0158] Clause 17. The marine controllable-pitch propeller (1) of any preceding clause, wherein the pitch adjusting member (20) is rotationally fixed to the propeller blade (10) regarding rotation around the length axis of the drive shaft (d).

[0159] Clause 18. A propeller system (103) for a boat (100), comprising: [0160] a shaft assembly (130), coaxial with a propeller axis (X130) of the propeller system (103); [0161] a primary propeller (140), comprising primary blades (141) carried by the shaft assembly (130), driven in rotation by the shaft assembly (130) around the propeller axis (X130), each primary blade (141) being rotatable relative to the shaft assembly (130), around a respective pitch axis (R141) perpendicular to the propeller axis (X130) and extending along said primary blade (141), between a first pitch orientation and a second pitch orientation; and [0162] a secondary propeller (150), comprising secondary blades (151) carried by the shaft assembly (130), driven in rotation by the shaft assembly (130) around the propeller axis (X130), each secondary blade (151) being rotatable relative to the shaft assembly (130), around a respective folding axis (R151) perpendicular to the propeller axis (X130) and to said secondary blade (151), between a deployed orientation and a folded orientation.

[0163] Clause 19. The propeller system (103) according to clause 18, wherein the propeller system (103) comprises a motor (105), operatively coupled to the shaft assembly (130), via a front shaft end (137) of the shaft assembly (130), for driving the primary propeller (140) and the secondary propeller (150) in rotation around the propeller axis (X130), by driving the shaft assembly (130), wherein the primary propeller (140) is positioned between the front shaft end (137) and the secondary propeller (150).

[0164] Clause 20. The propeller system (103) according to clause 19, wherein the motor (105) is an electric motor (105) configured to drive the shaft assembly (130) in rotation for propelling the boat (100) and to be driven in rotation by the shaft assembly (130) for generating electrical power.

[0165] Clause 21. The propeller system (103) according to any one of the preceding clauses, wherein the pitch orientation of said primary blades (141) is adjustable, in that each primary blade (141) is configured to be positioned in at least one desired pitch orientation between the first pitch orientation and the second pitch orientation.

[0166] Clause 22. The propeller system (103) according to any one of the preceding clauses, wherein the primary blades (141) may be oriented to a feathering pitch orientation.

[0167] Clause 23. The propeller system (103) according to any one of the preceding clauses, wherein the propeller system (103) comprises a differential planetary gear (120) by means of which the electrical motor (105) is operatively connected to the primary propeller (140) and to the secondary propeller (150).

[0168] Clause 24. The propeller system (103) according to clause 23, wherein the propeller system (103) comprises a brake (125) for immobilizing or at least braking the secondary propeller (150) relative to the primary propeller (140), in rotation around the propeller axis (X130) and/or for immobilizing or at least braking the secondary propeller (150), in rotation around the propeller axis (X130), relative to a stator (106) of the electric motor (105) or to a hull (102) of the boat (100) or to a stern of the boat (100).

[0169] Clause 25. The propeller system (103) according to any one of the preceding clauses, wherein the shaft assembly (130) comprises: [0170] an outer hub (132), coaxial with the propeller axis (X130), the primary propeller (140) being carried and driven by the outer hub (132); and [0171] an inner shaft (131), coaxial with the propeller axis (X130), rotatably received in the outer hub (132), the secondary propeller (150) being carried and driven by the inner shaft (131).

[0172] Clause 26. The propeller system (103) according to any one of the preceding clauses, wherein the primary blades (141) and the secondary blades (151) are mechanically coupled to each other by a mechanical coupling (160), so that the orientation of the primary blades (141) around the pitch axes (R141) and the orientation of the secondary blades (151) around the folding axes (R151) are dependent from each other.

[0173] Clause 27. The propeller system (103) according to any one of the preceding clauses, wherein the shaft assembly (130) comprises an axial bearing (136) interposed between the primary propeller (140) and the secondary propeller (150).

[0174] Clause 28. The propeller system (103) according to any one of the preceding clauses, wherein the shaft assembly (130) according to any one of clauses 18 to 27 comprises the drive shaft (d) according to any one of clauses 1 to 17 and the primary propeller (140) according to any one of clauses 18 to 27 is a marine controllable-pitch propeller according to any one of clauses 1 to 17.

[0175] Clause 29. A boat (100) including at least one propeller system (103) according to any one of clauses 87 to 28.

[0176] Clause 30. The boat (100) according to claim 29, wherein the boat (100) is a sailboat.

[0177] Clause 31. The boat (100) according to claim 29, wherein the boat (100) is a motor boat devoid of sail.

[0178] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms a, an, and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term and/or includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms comprises, comprising, includes, and/or including when used herein specify the presence of 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.

[0179] It will 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, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0180] Relative terms such as below or above or upper or lower or horizontal or vertical may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being connected or coupled to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being directly connected or directly coupled to another element, there are no intervening elements present.

[0181] 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 will be further understood that 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 will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0182] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the inventive concepts being set forth in the following claims.