WO2023061606A1

WO2023061606A1 - Cyclorotors

Info

Publication number: WO2023061606A1
Application number: PCT/EP2021/078581
Authority: WO
Inventors: Lionel Julliand; Jorgen JORDE; Theo GRALL
Original assignee: Ge Energy Power Conversion Technology Ltd
Priority date: 2021-10-15
Filing date: 2021-10-15
Publication date: 2023-04-20
Also published as: CN118103292A; KR20240073101A

Abstract

A cyclorotor (1) is described that can be used as a propulsor for a marine vessel. The cyclorotor (1) includes a rotary housing (2) comprising a main body (18) and a plurality of blade modules (16a, 16b,..., 16f) arranged circumferentially around the main body (18). The cyclorotor (1) also includes a plurality of blade assemblies, each blade assembly being located in a respective blade module (16a, 16b,..., 16f) and having a blade (4a, 4b,..., 4f) extending from the rotary housing (2) with a blade axis about which it can be pivoted relative to the rotary housing. Each blade assembly is associated with a blade actuator comprising an electric motor and having a drive shaft, a driving gear mechanically connected to the drive shaft and a driven gear mechanically connected to the respective blade assembly for pivoting the respective blade (4a, 4b,..., 4f) about its blade axis. Each blade module (16a, 16b,..., 16f) is preferably adapted to be detached and removed from the main body (18).

Description

TITLE

Cyclorotors

DESCRIPTION

Technical Field

The present invention relates to cyclorotors, and in particular to cyclorotors that can be used as propulsors when mounted to the hull of a marine vessel. However, the cyclorotors can also be used as turbines such as wind turbines or water turbines.

Background Art

Known propulsors include a plurality of blades extending from a rotary housing, where each blade can be pivoted by a blade actuator about a respective blade axis to provide thrust in any direction normal to the axis of rotation of the rotary housing. Such propulsors are sometimes also referred to as cyclorotors, cycloidal propellers or propulsion units and Voi th- Schneider propellers operating in cycloidal or trochoidal modes.

Each blade actuator can use one or more of mechanical, hydraulic, pneumatic, and electric actuators, e.g., an electric motor, to pivot the respective blade about its blade axis.

Summary of the invention

The present invention provides a cyclorotor comprising: a rotary housing comprising a main body and a plurality of blade modules arranged circumferentially around the main body; a plurality of blade assemblies, each blade assembly being located in a respective blade module and having a blade extending from the rotary housing with a blade axis about which it can be pivoted relative to the rotary housing; and a plurality of blade actuators, each blade actuator being associated with a respective one of the blade assemblies; wherein each blade actuator comprises: an electric motor having a drive shaft; a driving gear mechanically connected to the drive shaft; and a driven gear mechanically connected to the driving gear and to the respective blade assembly for pivoting the respective blade about its blade axis.

Each blade actuator defines the angle of the respective blade relative to the rotary housing. For convenience, the term “driving gear” is used herein to refer to the gear that is mechanically connected to the drive shaft of the electric motor, and the term “driven gear” is used herein to refer to the gear that is mechanically connected to the respective blade assembly. This most accurately describes the situation where the drive shaft of the electric motor is being driven to rotate such that the driven gear is being mechanically driven by the driving gear to pivot the blade about its respective blade axis. However, it will be readily understood that during normal operation of the cyclorotor, there will also be situations where the driving gear is effectively being driven to rotate by the driven gear or where such rotation is being prevented by the driving gear to maintain a desired blade angle. The term “mechanically connected” is used herein to include both direct and indirect connection between the respective components unless otherwise indicated.

The blade modules can extend radially outwardly from the main body and are preferably adapted to be independently removable from the main body so that a blade module can be replaced by another blade module if necessary. In some arrangements, the blade modules are not removable from the main body. This might be the case for smaller cyclorotors, for example.

A structural part of each blade module defines an outer housing or casing with an interior in which the respective blade assembly is located. A structural part of the main body defines an outer housing or casing with an interior in which the electric motors of the blade actuators can be located. The electric motor of each blade actuator can also be located in the respective blade module. The components of each blade actuator can therefore all be located in the respective blade module, or they can be distributed between the respective blade module and the main body of the rotary housing.

The driving gear of each blade actuator can be disengagable from the drive shaft of the respective electric motor and/or disengagable from the driven gear. This allows for blade freewheeling. Blade freewheeling can also be possible if the respective electric motor is non-operational, provided that the electric motor is not a permanent magnet motor - i.e., an electric motor with a rotor where the rotor poles are defined by a plurality of permanent magnets instead of a rotor winding. Each electric motor can have any suitable construction.

The driving gear and the driven gear of each blade actuator can define a transmission gear located in the respective blade module for pivoting the respective blade about its blade axis. In other words, the teeth of the driving gear and the driven gear can be meshed with each other. In another arrangement, the driving gear and the driven gear of each blade actuator can be indirectly mechanically connected by means of a drivetrain. In other words, the teeth of the driving gear and the driven gear of each blade actuator do not need to be meshed with each other but can be mechanically connected by any suitable drivetrain such as one or more drive belts, drive chains or gear trains, for example. If the drivetrain includes a drive belt or drive chain, for example, it will be readily understood that the term “gear” can be considered to include other components such as pulleys, sprockets, platewheels etc. that are in suitable engagement with the drive belt or drive chain.

The driving gear of each blade actuator can be directly mechanically connected to the drive shaft of the respective electric motor. The driving gear of each blade actuator can be indirectly mechanically connected to the drive shaft of the respective electric motor by means of a drivetrain, e.g., one or more shafts, drive belts, drive chains or gear trains. In general terms, any suitable drivetrain(s) can be utilised to mechanically connect the drive shaft of each electric motor with the respective blade assembly so that rotation of the drive shaft results in pivoting of the blade about its blade axis.

If the electric motors are located in the main body of the rotary housing, a drivetrain of each blade actuator can extend through an opening that connects the interior of the main body with the interior of the respective blade module. Each drivetrain can be adapted to be selectively reconfigured so that it does not extend through or otherwise obstruct the opening. This allows the openings between the main body and the blade modules to be independently sealed for blade module removal and replacement as described in more detail below. It also means that the drivetrain does not extend across the interface along which the blade module will be detached from the main body. In other words, reconfiguring the drivetrain can involve mechanically disconnecting the drive shaft and the driving gear and/or the driving gear and the driven gear so that the blade module can be detached and removed from the main body if it needs to be replaced. Each drivetrain can be reconfigured in any suitable way and be capable of being repositioned so that it no longer extends through the opening or across the interface.

If a drivetrain of each blade actuator includes a drive belt or drive chain that extends through the respective opening or across the respective interface, the drive belt or drive chain can be disconnected and either removed or repositioned so that the opening is no longer obstructed. This can disengage the driving gear from the driven gear, for example.

Each drivetrain that mechanically connects the drive shaft of the respective electric motor with the driving gear can include one or more shafts that extend through the respective opening or across the interface. The one or more shafts can be used to engage and disengage transmission between the drive shaft and the driving gear. In one arrangement, one end of a shaft can be mechanically connected to the drive shaft of the respective electric motor and the other end of the shaft can be mechanically connected to the driving gear. The shaft can be releasably connected to one or both of the drive shaft and the driving gear by a suitable coupling, e.g., a pair of flanges that can be connected together by mechanical fixings such as bolts or screws or other suitable securing means. When the flanges are disconnected by untightening and removing or releasing the mechanical fixings, the shaft can be removed completely or moved to a position where it does not extend through the opening or across the interface. The shaft can be movable or repositionable relative to the drive shaft of the respective electric motor (e.g., it can be capable of being moved between a driving position where it is connected to the driving gear, and a retracted position where it is located in the main body or the blade module and does not extend through the opening or across the interface) or it can be fixed relative to the drive shaft. If the shaft is movable relative to the drive shaft of the electric motor, it might be able to slide on the drive shaft between the driving and retracted positions while remaining mechanically connected to it. If the shaft is fixed to the drive shaft of the electric motor, the drive shaft and the electric motor can be movable or repositionable - for example, they can be translated or rotated relative to the main body of the rotary housing - such that the shaft no longer extends through the opening or across the interface but is located entirely within the main body of the rotary housing. (The drive shaft and the electric motor can also be movable or repositionable such that the drive shaft no longer extends through the opening or across the interface if the drive shaft is releasably mechanically connected directly to the driving gear without the use of a drivetrain, for example.) This disengages the driving gear from the drive shaft of the respective electric motor. After a replacement blade module has been installed, the shaft can be mechanically reconnected to one or both of the drive shaft and the driving gear, e.g., by reinserting and tightening the mechanical fixings or other suitable securing means to reconnect the flanges. The shaft can be part of the replacement blade module and can be movable or repositionable relative to the drive shaft of the respective electric motor, e.g., between a retracted position during blade module replacement and a driving position where it extends through the respective opening or across the interface and can be mechanically connected to the drive shaft of the electric motor that is located in the main body of the rotary housing. This reengages the driving gear of the blade actuator with the drive shaft of the respective electric motor. In another arrangement, each drivetrain can include two or more shafts that can be used to engage and disengage transmission between the drive shaft and the driving gear. One shaft can be mechanically connected to the drive shaft of the respective electric motor and the other shaft can be mechanically connected to the driving gear. The shafts can be releasably connected together by a suitable coupling, e.g., a pair of flanges that can be connected together by mechanical fixings such as bolts or screws or other suitable securing means. When the flanges are disconnected by untightening and removing or releasing the mechanical fixings, at least one of the shafts can be moved to a position where the driveshaft does not extend through the opening or across the interface. This disengages the driving gear from the drive shaft of the respective electric motor. In one arrangement, one of the shafts can be fixed and the other can be movable or repositionable. The fixed shaft might typically be connected to the driving gear and can be mounted for rotation by one or more bearings. The fixed shaft might typically be located in the blade module and does not extend through the respective opening or cross the interface. The fixed shaft, bearings and driving gear are therefore part of the blade module and will be removed with the blade module if it needs to be replaced. The movable shaft can be movable or repositionable relative to the drive shaft (e.g., it can be capable of being moved between a driving position where it is connected to the fixed shaft, and a retracted position where it is located in the main body and does not extend through the opening or across the interface) or it can be fixed relative to the drive shaft. If the movable shaft is movable relative to the drive shaft, it might be able to slide on the drive shaft between the driving and retracted positions while remaining mechanically connected to it. If the movable shaft is fixed to the drive shaft, the drive shaft and the electric motor can be movable or repositionable - for example, translated or rotated relative to the main body of the rotary housing - such that the movable shaft no longer extends through the opening or across the interface but is located entirely within the main body of the rotary housing. After being disconnected from the other shaft, the shaft that is mechanically connected to the drive shaft can be completely removed from the drive shaft. After a replacement blade module has been installed, the movable shaft can be mechanically reconnected to the fixed shaft of the replacement blade module, e.g., by reinserting and tightening the mechanical fixings or other suitable securing means to reconnect the flanges. This reengages the driving gear of the blade actuator with the drive shaft of the respective electric motor.

Each blade assembly can comprise exactly one bearing assembly rotatably mounting the respective blade. Each bearing assembly (or “slewing bearing”) can include a stationary ring that is fixed to the blade module housing and a rotating ring that is fixed to a root part of the respective blade. The stationary ring of each bearing assembly can be fixed to the blade module housing by a plurality of mechanical fixings, e.g., bolts or screws, or other suitable securing means. The rotating ring of each bearing assembly can be fixed to the blade by a plurality of mechanical fixings, e.g., bolts or screws, or other suitable securing means.

The driven gear of each blade actuator can be formed as an integral part of the rotating ring of the bearing assembly or as a separate component that is fixed to the rotating ring so that they rotate together as a unitary rotating component of the bearing assembly. If the driven gear is formed as an integral part of the rotating ring of the bearing assembly, the teeth of the driven gear can be formed on a surface of the rotating ring. If the driven gear is formed as a separate component, the driven gear can be formed as a ring and the teeth of the driven gear are formed on a surface of the ring. The driven gear can be fixed to the rotating ring of the bearing assembly by a plurality of mechanical fixings, e.g., bolts or screws, or other suitable securing means.

If the driving gear and the driven gear of each blade actuator define a transmission gear, i.e., where the teeth are meshed with each other, the transmission gear can be a bevel gear. In this arrangement, the driven gear of each blade actuator can be a conical gear with an axis of rotation substantially parallel to the respective blade axis. The driving gear of each blade actuator can be a conical gear with an axis of rotation substantially perpendicular to the respective blade axis. The drive shaft and any optional drivetrain that mechanically connects the drive shaft to the driving gear can also have an axis of rotation substantially parallel to the respective blade axis. Such a construction provides physically compact blade assemblies. Any suitable type of conical gears can be used - e.g., mitre, straight, spiral etc.

If the driving gear and the driven gear are indirectly mechanically connected - e.g., by means of a drive belt or drive chain that is connected around the gears, or by one or more intermediate gears, the driving gear and the driven gear can have an axis of rotation substantially parallel to the respective blade axis. The driving gear can be directly mechanically connected to the drive shaft of the respective electric motor.

Each blade module can be removably connected to the main body of the rotary housing by a plurality of mechanical fixings (e.g., bolts or screws) or other suitable securing means. Each blade module is preferably a self-contained unit that includes a blade assembly and all of the mechanical components necessary for blade actuation apart from the electric motor in one arrangement. In this arrangement, a replacement blade module therefore only needs to be mechanically connected to the drive shaft of a respective electric motor that is positioned within the main body of the rotary housing in order to be fully operable. In another arrangement, all of mechanical components necessary for blade actuation, including the electric motor, are located in the replacement blade module. Both arrangements allow a faulty blade module to be easily removed and replaced as described in more detail below.

Each opening between the interior of the main body and the respective blade module is typically defined by a first opening formed in the structural part of the blade module and an aligned second opening formed in the adjacent structural part defining the main body. The interior of the rotary housing should be kept watertight if the cyclorotor is located in water during use - e.g., if it is mounted to the hull of a marine vessel or used as a water turbine. In this case, the blade modules are preferably removably secured to the main body in such a way as to maintain a watertight seal that prevents any water from entering the interior of the rotary housing. One or more seals can be provided between facing structural parts of each blade module and the main body and can extend around the opening. There will typically be different solutions for replacing a blade module depending on whether the cyclorotor interfaces are immersed in water or dry.

Both the first and second openings can be sealed by respective panels before the blade module is unsecured from the main body and replaced. A first panel can be used to temporarily seal the first opening in the structural part of the blade module so that water will not enter the interior of the blade module through the first opening when it is removed. A second panel can be used to temporarily seal the second opening in the structural part of the main body so that, when the blade module is removed, water will not enter the interior of the main body and the remaining blade modules through the second opening. This allows a faulty blade module to be removed and replaced without the need for dry dock facilities or ballasting, or without having to raise the water turbine. The first and second panels are preferably installed from inside the main body of the rotary housing. For example, the first opening can be slightly smaller than the second opening. The first opening can therefore be closed and sealed by securing the first panel to the structural part of the blade module to be replaced that surrounds the first opening and which is accessible through the larger second opening. The first panel can be fitted from inside the main body and is received through the larger second opening. Once the first panel has been secured, the second opening can be closed and sealed by securing the second panel to the structural part of the main body that surrounds the second opening. Engineer access can be provided into the interior of the main body so that the first and second panels can be installed.

Each panel can be removably secured to the respective structural part of the blade module or the main body by a plurality of mechanical fixings (e.g., bolts or screws) or some other suitable securing means.

One or more seals can be provided between the first panel and the structural part of the blade module to provide a watertight seal therebetween. One or more seals can be provided between the second panel and the structural part of the main body to provide a watertight seal therebetween. The one or more seals can extend around the respective opening.

Once the main body and the blade module to be replaced have been made watertight, the mechanical fixings or other securing means that are used to removably secure the blade module to the main body can be untightened and removed or released, preferably from inside the main body. Removing or releasing the mechanical fixings or other securing means must not compromise the watertightness of either the blade module to be replaced or the main body. For example, any openings in the structural part of the main body or blade module for receiving mechanical fixings can be filled with suitable plugs or caps, or watertight mechanical fixings can be used that include one or more seals between the fixing shaft and the inner surface of the respective opening and which are untightened or released but not fully removed from the opening.

Once the mechanical fixings or other securing means have been untightened and removed or released, the blade module is able to be detached from the rest of the rotary housing and can be moved away from the main body in a controlled manner.

If the cyclorotor is not located in water during blade module replacement, the mechanical fixings or other securing means can simply be untightened and removed or released without any steps being taken to temporarily seal the main body and the blade module to be replaced or make them watertight. This might be the case if the cyclorotor is mounted to the hull of a marine vessel in dry dock or ballasted to be above the waterline, for example. However, even if the cyclorotor is not located in water, it is normally still preferred that the first panel is secured to blade module to temporarily cover or seal the first opening before it is removed from the main body.

During blade module replacement, the weight of the blade module must normally be supported by a support structure. In one arrangement, the blade module is attached to winch cables that can be used to lower or lift the blade module after it has been detached from the main body. In another arrangement, the blade module might be supported from above or below by a cradle or other support structure. The process by which the blade module is detached from the main body will normally depend on how the blade module is structurally connected to the main body.

A replacement blade module can be lowered or lifted using attached winch cables (or some other support structure) until it is aligned with the main body. It can then be secured to the main body by inserting and tightening the mechanical fixings or other securing means. The replacement blade module can be sealed during the installation process - e.g., by a panel that is secured to temporarily cover or seal the opening in the structural part of the blade module. After the replacement blade module has been properly secured to the main body in a watertight manner, any panels that are secured to the main body and the blade module to temporarily seal the openings can be removed to unseal the opening that connects the interior of the main body with the interior of the replacement blade module. If the driving gear of the blade actuator of the replacement blade module is to be indirectly mechanically connected to the drive shaft of the respective electric motor by a drivetrain, the drivetrain can be reengaged so that it passes through the opening. This can include reconnecting one or more shaft couplings, for example. Alternatively, any drive belts or drive chains that were removed can also be reattached or reconnected so that they pass through the opening. This can reengage the driving gear with the driven gear, for example.

The present invention provides a method of repairing a cyclorotor as described above, the method comprising: sealing a first opening in a blade module to be replaced and optionally an aligned second opening in the main body; and removing the sealed blade module from the main body.

The method can further comprise disengaging the driving gear from one or both of the drive shaft of the respective electric motor and the respective driven gear prior to sealing. This can include reconfiguring a drivetrain so that it does not extend through or otherwise obstruct the first and second openings if the electric motor is located in the main body, for example.

The method can further comprise: securing a replacement sealed blade module to the main body; and unsealing a first opening in the replacement blade module and the aligned second opening in the main body if sealed.

The method can further comprise reengaging the driving gear with one or both of the drive shaft of the respective electric motor and the respective driven gear after unsealing. This can include reconnecting or repositioning a drivetrain so that it extends through the first and second openings.

The cyclorotor can be mounted to the hull of a marine vessel as a propulsor.

An access opening can be provided in the hull of the marine vessel through which winch cables can be attached to the blade module to be replaced from above. The access opening can be formed in an annular collar that surrounds the rotary housing and which forms a structural part of the hull of the marine vessel. The profile of the inner surface of the collar preferably conforms generally to the outer profile of the rotary housing and an annular gap or clearance is provided between the rotary housing and the collar to allow the rotary housing to rotate freely. The rotary housing can be rotated until the blade module to be removed is aligned with the access opening. In some arrangements, two or more access openings and appropriately spaced.

The cyclorotor can include a slewing bearing for rotatably mounting the rotary housing. The slewing bearing can comprise a rotating ring fixed to the rotary housing and a stationary ring. The stationary ring can be adapted to be fixed to the hull of the marine vessel, optionally directly or indirectly by means of a mounting plate or mounting structure. The cyclorotor can include a main electric machine (e.g., an electric motor or generator) with a drive shaft that is mechanically connected to the rotating ring of the slewing bearing. If the cyclorotor is used a propulsor for a marine vessel, the main electric machine can be operated as a motor to rotate the rotary housing to generate thrust. If the cyclorotor is used as a turbine, the main electric machine can be operated as a generator where rotation of the rotary housing, e.g., by moving air or water, will generate electrical power.

The present invention further provides a marine vessel comprising a cyclorotor as described above and an earthing assembly, wherein the earthing assembly comprises an earthing circuit between each blade assembly and an earthing connection provided on the hull of the marine vessel. If the marine vessel uses impressed current cathodic protection (ICCP) for corrosion protection, the earthing system is designed to prevent the blade assembly and other parts of the cyclorotor from being damaged by the circulating currents that protect the marine vessel against corrosion.

Drawings

Figure 1 is a perspective view of a propulsor according to the present invention;

Figure 2 is a perspective view of the propulsor shown in Figure 1 installed in the hull of a marine vessel;

Figure 3 is a cross section view of the installed propulsor shown in Figure 2;

Figures 4 to 7 are schematic views showing a blade module and blade actuator;

Figures 8 and 9 are schematic views showing first and second panels secured using mechanical fixings;

Figure 10 is a schematic view showing first and second panels secured using watertight mechanical fixings;

Figures 11 and 12 are schematic views of the propulsor shown in Figure 1 with a blade module removed;

Figure 13 is a schematic view of an earthing assembly for a propulsor according to the present invention; and Figure 14 is a schematic view of the propulsor according to the present invention installed in a marine vessel.

Although the following description describes a cyclorotor that is used as a propulsor for a marine vessel, it will be readily understood that the same principles can be applied to other types of cyclorotor, e.g., for wind or water turbines.

Referring to Figures 1 to 3, a propulsor 1 for a marine vessel includes a rotary housing 2. Six blades 4a, 4b, ..., 4f extend axially from the lower surface 2a of the rotary housing 2. Each blade 4a, 4b, ..., 4f has a respective blade axis 6 about which it can be pivoted relative to the rotary housing 2 by a blade actuator 8. The propulsor 1 includes six blade actuators 8. Each blade actuator 8 includes an electric motor 10, a drivetrain 12, and a transmission gear 14 for pivoting the respective blade. Each blade 4a, 4b, ..., 4f is mounted in a respective blade module 16a, 16b, ..., 16e, 16f that extends radially outwardly from a main body 18 and is mounted on a single bearing assembly 20 (or “slewing bearing”).

In Figure 3, two of the six blade actuators 8 and two of the six bearing assemblies 20 are shown schematically. Figures 4 to 6 show one of the blade modules 16d in more detail, and in particular the construction of the respective blade actuator 8 and the respective blade assembly including the bearing assembly 20. It will be readily understood that the other blade actuators and blade assemblies have the same construction. For the following description, it will be assumed that the blade module 16d is to be replaced, e.g., because it is faulty. But it will be readily understood that the same process can be used to replace any of the blade modules 16a, 16b, ..., 16f.

A structural part 22 of each blade module 16a, 16b, ..., 16f forms part of an outer housing and defines an interior in which the respective blade assembly 20 and part of the respective blade actuator 8 is located. Each bearing assembly 20 includes a stationary ring 24 that is fixed to the blade module housing - and in particular to a circular mounting ring - by mechanical fixings, e.g., bolts or screws, and a rotating ring 26 that is fixed to a root part of the respective blade 4a, 4b, 4f by mechanical fixings, e.g., bolts or screws.

A driven gear 28 is formed as a separate component that is fixed to the rotating ring 26 by mechanical fixings, e.g., bolts or screws, so that they rotate together as a unitary rotating component of the bearing assembly 20. The driven gear 28 is a conical gear with an axis of rotation substantially parallel to the respective blade axis 6.

A driving gear 30 is mechanically connected to the drive shaft 32 of the respective electric motor 10 by the drivetrain 12. The driving gear 30 of each blade actuator 8 is also a conical gear with an axis of rotation substantially perpendicular to the respective blade axis 6. The driven gear 28 and the driving gear 30 together define a bevel gear as a single-stage transmission gear 14 for pivoting the respective blade when the driving gear is rotated by the drive shaft 32 and the drivetrain 12.

The drivetrain 12 includes a first shaft 12a that is mechanically connected to the drive shaft 32 and a second shaft 12b that is mechanically connected to the driving gear 30 and supported for rotation by a pair of bearings 34. The second shaft 12b is located entirely within the blade module 16f and is fixed (apart from rotation).

The first shaft 12a includes a radial flange and the second shaft 12b includes a radial flange. The flanges together define a coupling with aligned openings that allow the flanges to be releasably connected together by mechanical fixings, e.g., bolts or screws. The coupling allows the driving gear 30 of each blade actuator 8 to be disengaged from the drive shaft 32 of the respective electric motor 10 as described in more detail below.

A structural part 36 of the main body 18 forms part of an outer housing and defines an interior in which the six electric motors 10 are located. In another arrangement, each electric motor can be located in a respective blade module. Each driving gear can be mechanically connected to the drive shaft of the respective electric motor and can be mechanically connected directly with the driven gear (i.e., as a single-stage transmission gear) or indirectly by means of a drive belt or drive chain, for example.

The rotary housing 2 includes six openings 38, each opening providing access from the interior of the main body 18 to the interior of a respective one of the blade modules 16a, 16b, ..., 16e, 16f. Each opening 38 is defined by a first opening 40 in the structural part 20 of the respective blade module and an aligned second opening 42 formed in the adjacent structural part 36 defining the main body 18.

During normal use, each drivetrain 12 extends through a respective opening 38 and mechanically connects the drive shaft 32 of the respective electric motor 10 to the driving gear 30. It will be readily understood that if the electric motors 10 are located in the main body 18 and the driving gears 30 are located in a respective blade module 16a, 16b, ..., 16f, each drivetrain 12 must cross an interface between the main body and the respective blade module, where each interface is effectively defined by the opening 38. If it is necessary to remove one of the blade modules 16a, 16b, ..., 16f, the respective opening 38 must often be sealed. In order to seal the respective opening, it is necessary to move or reposition the drivetrain 12 so that it does not extend through the opening or cross the interface along which the blade module will be detached from the main body 18.

The mechanical fixings used to connect the flanges of the first and second shafts 12a and 12b can be removed so that they are no longer connected. As shown in Figure 5, the electric motor 10 can then be moved backwards on its mounting so that the first shaft 12a is spaced apart from the second shaft 12b - which is fixed - and no longer extends through the respective opening 38. The second shaft 12b is now no longer mechanically connected to the drive shaft 32 of the respective electric motor 10 and the disconnected drivetrain 12 will not prevent the blade module 16d from being detached and removed from the main body 18 once the opening 38 is properly sealed. The first shaft 12a can subsequently be removed from the drive shaft 32 as shown in Figure 6. It will be readily understood that each drivetrain can also be reconfigurable in other ways so that it no longer extends through the opening or across the interface between the main body and the blade module to be replaced. It will also be readily understood that alternative drivetrains can be used, which might include one or more of drive belts, drive chains and gear trains, for example. Such drive belts or drive chains, for example, can be at least partly removed or disconnected if they extend through the opening or across the interface.

Once the drivetrain 12 no longer extends through the opening 38 between the interior of the main body and the interior of the blade module 16d to be replaced, the opening can be sealed. In particular, both the first and second openings 40 and 42 can be sealed by respective panels 44a and 44b (see Figure 7). A first panel 44a is used to temporarily seal the first opening 40 in the structural part 22 of the blade module 16d so that water will not enter the interior of the blade module through the first opening when it is removed. A second panel 44b is used to temporarily seal the second opening 42 in the structural part 38 of the main body 18 so that, when the blade module 16d is removed, water will not enter the interior of the main body and the remaining blade modules through the second opening. The first and second panels 44a and 44b are installed from inside the main body of the rotary housing. As shown schematically in Figures 8 to 10, the first opening 40 is slightly smaller than the second opening 42. The first opening 40 can therefore be closed and sealed by securing the first panel 44a to the structural part 22 of the blade module to be replaced that surrounds the first opening and which is accessible through the larger second opening 42. The first panel 44a can be fitted from inside the main body 18 and is received through the second opening 42. Once the first panel 44a has been secured, the second opening 42 can be closed and sealed by securing the second panel 44b to the structural part 36 of the main body 18 that surrounds the second opening 42. The first and second panels 44a and 44b are removably connected to the respective structural part of the blade module or the main body by a plurality of mechanical fixings, e.g., bolts or screws.

In Figures 8 and 9, only the mechanical fixings 46 that are used to secure the first panel 44a to the blade module 16d are shown. The mechanical fixings 46 are received through openings in the first panel 44a and are screwed into aligned openings in the structural part 22 of the blade module 16d to be removed. Figures 8 and 9 also show how the blade module 16d is removably connected to the main body 18 by a plurality of mechanical fixings 48, e.g., bolts or screws. The mechanical fixings 48 are received through openings 50 in the second panel 44b. Additional openings (not shown) in the second panel receive the mechanical fixings that secure the second panel to the structural part 36 of the main body 18. The mechanical fixings for securing the second panel 44b to the main body 18 are received through the openings in the second panel and are screwed into aligned openings in the structural part 36 of the main body. The openings 50 in the second panel 44b provide access to the mechanical fixings 48, which are received through openings 52 in the structural part 36 of the main body 18 and are screwed into aligned openings 54 in the structural part 22 of the blade module 16d.

Once the main body 18 and the blade module 16d to be replaced have been made watertight by securing the first and second panels 44a and 44b, the mechanical fixings 48 that secure the main body and the blade module together can be removed, preferably from inside the main body 18. The openings 52 in the structural part 36 of the main body 18 are then filled with plugs or caps 56 so that the main body remains watertight. Alternatively, as shown in Figure 10, watertight mechanical fixings 58 can be used. Such watertight mechanical fixings 58 are released from the structural part 22 of the blade module 16d but not removed from the structural part 36 of the main body 18. One or more o-ring seals 60 are provided between the shaft of each mechanical fixing 58 and the respective opening 52 in the structural part 22 of the main body 18 to maintain a watertight seal. In Figures 8 to 10, other o-rings are also shown that provide a watertight seal between facing surfaces.

Once the mechanical fixings 48 or 58 have been untightened and removed or released, the blade module 16d is able to be detached from the rest of the rotary housing and can be moved away from the main body 18 in a controlled manner. Figures 11 and 12 show the blade module 16d after being detached from the main body 18. Adjacent side plates can also be detached before the blade module 16d is detached as shown.

After a replacement blade module has been installed and secured to the main body 18 by inserting and tightening the mechanical fixings 48 or 58 from inside the main body, the first and second panels 44a and 44b can be removed by untightening and removing the mechanical fixings. It will be readily understood that the first panel 44a will have been secured to the replacement blade module to seal the opening in the casing or housing of the replacement blade module prior to it being installed in place of the removed blade module. The blade module is therefore maintained in a watertight condition during blade module replacement.

After the opening 38 between the interior of the main body 18 and the interior of the replacement blade module has been opened, the first shaft 12a can be reconnected to the drive shaft 32 and the electric motor 10 can be moved forwards on its mounting so that the flanges of the first and second shafts 12a and 12b are in abutment. The flanges can then be reconnected together such that the drive shaft 32 is mechanically connected to the driving gear 30 of the replacement blade module by the drivetrain 12. It will be readily understood that each drivetrain can also be reconfigurable in other ways so that it extends through the opening and mechanically connects the drive shaft with the driving gear.

As shown in Figure 3, the propulsor 1 includes a slewing bearing 62 for rotatably mounting the rotary housing 2. The slewing bearing 62 includes a rotating ring fixed to the rotary housing 2 and a stationary ring. The stationary ring is adapted to be fixed to the hull of the marine vessel by means of a mounting plate 64.

The slewing bearing 62 includes a driven gear that is fixed to the rotating ring. A plurality of rolling elements (not shown) are positioned between the driven and stationary rings.

Figures 2 and 3 show the propulsor 1 mounted within an annular collar H that forms a structural part of the hull of the marine vessel. The annular collar includes an upper annular surface Hl, a first inner cylindrical surface H2, an inner frustoconical surface H3, and a second inner cylindrical surface H4. The inner surface H2 is adjacent the slewing bearing 62 and the inner surfaces H3 and H4 define an inner profile of the collar that conforms generally to the outer profile of the rotary housing 2. The rotary housing 2 and the inner surfaces H3 and H4 of the collar are separated by a gap G that allows the rotary housing to rotate freely. The gap G has an open end at the lower surface 2a of the rotary housing 2 and a closed end adjacent the slewing bearing 62. One or more static or dynamic seals (not shown) can be provided at the closed end to provide a watertight seal and prevent the ingress of water into the interior of the rotary housing 2 past the slewing bearing 62.

During blade module replacement, the weight of the removed blade module 16d must be supported by a support structure (not shown). In one arrangement, the blade module 16d is attached to winch cables that can be used to lower or lift the blade module after it has been detached from the main body. Winch cables can also be used to lower or lift the replacement blade module. The winch cables can be secured to a suitable part of the blade module and can pass through an opening O in the annular collar H that surrounds the propulsor - see Figure 2. The propulsor 1 can be rotated so that the blade module 16d to be replaced is arranged underneath the opening O and the winch cables can be passed through the opening and secured to the blade module. It will be readily understood that other ways of supporting a blade module can also be used.

The mounting plate 64 is fixed to the collar H by means of an intermediate fixing structure (not shown) that is positioned between the lower surface of the mounting plate and the upper annular surface Hl of the collar. In an alternative arrangement, the stationary part of the slewing bearing 62 can be fixed directly to the hull of the marine vessel, e.g., to the inner surface H2 of the collar.

Two driving gears 66a and 66b (or “pinion gears”) are located radially inside the driven gear of the slewing bearing 62. The first driving gear 66a is mechanically connected to a drive shaft 68a of a first main electric motor 70a. The second driving gear 66b is mechanically connected to a drive shaft 68b of a second main electric motor 70b.

The driven gear of the slewing bearing 62 and the first driving gear 66a define a first single-stage transmission gear. The driven gear of the slewing bearing 62 and the second driving gear 66b define a second single-stage transmission gear in parallel with the first single-stage transmission gear.

The first and second main electric motors 70a and 70b are mounted on the mounting plate 64.

The drive shafts 68a and 68b of the first and second main electric motors 70a and 70b are aligned substantially parallel to the axis of rotation of the rotary housing 2.

Figure 13 shows an earthing assembly 100. The earthing assembly 100 provides an electrical earthing circuit 102 between each blade assembly 104 and the hull 106 of the marine vessel. (In Figure 13 only one blade assembly 104 is shown to be connected to an earthing connection 108 on the marine vessel by a respective earthing circuit 102, but it will be readily understood that all of the blade assemblies are preferably connected to the earthing connection in a similar manner.) Each earthing circuit 102 can include means such as a brush 110 for interfacing the fixed earthing circuit to the blade root which can pivot about the respective blade axis. The brush 110 may be in sliding contact with an annular track 112 on the blade root. A slip ring or other suitable coupling 114 can be used to connect the part of the earthing circuit that rotates with the rotary housing with the part of the earthing circuit that is stationary relative to the hull of the marine vessel. In Figure 13 a power unit P is shown for generating the circulating currents that protect the marine vessel as part of an impressed current cathodic protection (ICCP) system. The earthing assembly 100 provides a low impedance electrical path for these circulating currents from each blade assembly 104 to the earthing connection 108.

Claims

- 23 - CLAIMS

1. A cyclorotor (1) comprising: a rotary housing (2) comprising a main body (18) and a plurality of blade modules (16a, 16b, ..., 16f) arranged circumferentially around the main body (18); a plurality of blade assemblies, each blade assembly being located in a respective blade module and having a blade (4a, 4b, ..., 4f) extending from the rotary housing (2) with a blade axis (6) about which it can be pivoted relative to the rotary housing (2); and a plurality of blade actuators (8), each blade actuator (8) being associated with a respective one of the blade assemblies; wherein each blade actuator (8) comprises: an electric motor (10) having a drive shaft (32); a driving gear (30) mechanically connected to the drive shaft (32); and a driven gear (28) mechanically connected to the driving gear (30) and to the respective blade assembly for pivoting the respective blade (4a, 4b, ..., 4f) about its blade axis (6).

2. A cyclorotor (1) according to claim 1, wherein each blade assembly comprises exactly one bearing assembly (20) rotatably mounting the respective blade (4a, 4b, ..., 4f), wherein each bearing assembly (20) includes a stationary ring (24) that is fixed to a blade module housing and a rotating ring (26) that is fixed to a root part of the respective blade (4a, 4b, ..., 4f).

3. A cyclorotor according to claim 2, wherein the driven gear is formed as an integral part of the rotating ring of the respective bearing assembly and the teeth of the driven gear are formed on a surface of the rotating ring.

4. A cyclorotor (1) according to claim 2, wherein the driven gear (28) is formed as a separate component that is fixed to the rotating ring (26) of the respective bearing assembly (20).

5. A cyclorotor (1) according to claim 4, wherein the driven gear (28) is formed as a ring and the teeth of the driven gear (28) are formed on a surface of the ring.

6. A cyclorotor (1) according to any preceding claim, wherein the driving and driven gears (30, 28) of each blade actuator define a transmission gear (14) located in the respective blade module (16a, 16b, ..., 16f).

7. A cyclorotor (1) according to claim 6, wherein each transmission gear (14) is a bevel gear.

8. A cyclorotor (1) according to claim 7, wherein the driven gear (28) of each blade actuator (8) is a conical gear with an axis of rotation substantially parallel to the respective blade axis (6), and wherein the driving gear (30) of each blade actuator (8) is a conical gear with an axis of rotation substantially perpendicular to the respective blade axis (6).

9. A cyclorotor (1) according to any preceding claim, wherein the driving gear (30) of each blade actuator (8) is disengagable from the drive shaft (32) of the respective electric motor (10).

10. A cyclorotor (1) according to any preceding claim, wherein the driving gear (30) of each blade actuator (8) is disengagable from the driven gear (28).

11. A cyclorotor (1) according to any preceding claim, wherein the driving gear (30) of each blade actuator (8) is mechanically connected to one or both of the drive shaft (32) of the respective electric motor (10) and the respective driven gear (28) by a respective drivetrain (12).

12. A cyclorotor (1) according to any preceding claim, further comprising a plurality of openings (38), each opening providing access between the interior of the main body (18) and the interior of a respective one of the blade modules (16a, 16b, ..., 16f), wherein a drivetrain (12) of each blade actuator (8) extends through a respective opening (38) during normal use, and wherein the drivetrain (12) is adapted to be selectively reconfigured so that it does not extend through the opening (38) so that the opening (38) can be sealed for blade module replacement.

13. A cyclorotor (1) according to any of claims 1 to 11, further comprising a plurality of openings (38), each opening (38) providing access between the interior of the main body (18) and the interior of a respective one of the blade modules (16a, 16b, ..., 16f).

14. A cyclorotor (1) according to claim 13, wherein each opening (38) is defined by a first opening (40) formed in a structural part (22) of the blade module (16a, 16b, ..., 16f) and an aligned second opening (42) formed in an adjacent structural part (36) of the main body (18).

15. A cyclorotor (1) according to claim 14, further comprising a first panel (44a) removably connected to the structural part (22) of the blade module (16a, 16b, ..., 16f) for sealing the first opening (40), and a second panel (44b) removably connected to the structural part (36) of the main body (18) for sealing the second opening (42).

16. A cyclorotor according to claim 15, further comprising one or more seals between the first panel and the structural part of the blade module and extending around the first opening, and one or more seals between the second panel and the structural part of the main body and extending around the second opening.

17. A cyclorotor (1) according to any preceding claim, wherein each blade module (16a, 16b, ..., 16f) is removably connected to the main body (18) by a plurality of mechanical fixings (48; 58). - 26 -

18. A method of repairing a cyclorotor (1) according to any preceding claim, the method comprising: sealing a first opening (40) in a blade module (16d) to be replaced and optionally an aligned second opening (42) in the main body (18); and removing the sealed blade module (16d) from the main body (18).

19. A method according to claim 18, further comprising disengaging the driving gear (30) from one or both of the drive shaft (32) of the respective electric motor (10) and the respective driven gear (28) prior to sealing.

20. A method according to claim 18 or claim 19, further comprising: securing a replacement sealed blade module to the main body (18); and unsealing a first opening (40) in the replacement blade module and the aligned second opening (42) in the main body (18) if sealed.

21. A method according to any of claims 18 to 20, further comprising reengaging the driving gear (30) with one or both of the drive shaft (32) of the respective electric motor (10) and the respective driven gear (28) after unsealing.

22. A marine vessel comprising one or more cyclorotors (1) according to any of claims 1 to 17 mounted to the hull (H) of the marine vessel as a propulsor.

23. A marine vessel according to claim 22, wherein an access opening (O) is provided in the hull (H) of the marine vessel through which winch cables can be attached to a blade module to be replaced.

24. A marine vessel according to claim 23, wherein the access opening (O) is provided in an annular collar (H) that surrounds the rotary housing (2) and which forms a structural part of the hull of the marine vessel. - 27 -

25. A marine vessel according to any of claims 22 to 24, further comprising an earthing assembly (100), wherein the earthing assembly (100) comprises an earthing circuit (102) between each blade assembly (104) and an earthing connection (108) on the hull (106) of the marine vessel.