Method of mounting a tower mountable crane to a tower of a wind turbine

Abstract

A method for mounting a tower mountable crane (TMC) to a tower of an wind turbine, for example an offshore wind turbine, said tower having a central axis extending along a length of the tower in a vertical direction, said TMC comprising a base portion which is arranged to be connectable to a tower of a wind turbine, a boom having a base end pivotally connected to the base portion and a tip end arranged distally from the base end and a lifting hook connected to a tip end of the boom via a cable controlled by a winch, the method comprising: lifting a hoist block and mounting the hoist block to an upper portion of the tower, connecting the cable between the TMC and the hoist block such that the cable extends from the TMC to the hoist block and back to the TMC, lifting the TMC using a lifting wire of an external crane, tensioning the cable extending between the hoist block and the TMC to partially support the TMC via said cable; increasing the tension in the cable until the TMC is completely supported by said cable; and disconnecting the lifting wire of the external crane from the TMC. In this way, the TMC can be safely and easily transferred to the tower.

Description

[0001] Method of mounting a tower mountable crane to a tower of a wind turbine

[0002] Technical Field of the invention

[0003] The current invention generally concerns tower mountable cranes. More particularly, the invention relates to a method of installing a tower mountable crane onto a tower of an offshore wind turbine and a tower mountable crane configured to facilitate an installation, a maintenance and / or a repair of a wind turbine.

[0004] The current specification also discloses additional inventions related to systems comprising a tower mounted crane as well as methods involving the use of a tower mounted crane as well as supporting equipment for using a tower mounted crane.

[0005] For the sake of this specification the term “TMC” will be used to refer to a Tower Mountable Crane.

[0006] Furthermore, according to this specification, the term “Tower Mountable Crane” or “TMC” should be understood as a crane which is connected or connectable to a wind turbine, such that the crane is or can be supported by the wind turbine itself. In certain embodiments, the wind turbine mounted crane is connected to the tower of the wind turbine, at a location somewhere below the nacelle of the wind turbine. These types of cranes could also be called tower mounted cranes or wind turbine tower mounted cranes, but are still considered TMCs for the sake of this specification. In other embodiments, the TMC could be connected to the nacelle of the wind turbine or to a fixture arranged in the nacelle of the wind turbine. This is sometimes called a nacelle mounted crane or an up tower crane, but are also considered TMCs according to this specification. The term “tower mountable crane” is used to differentiate from a “free standing crane” or “external crane” which is located separate from the wind turbine tower, for example a crane which is arranged on the ground next to the wind turbine or floating next to a wind turbine tower on a barge or other floating vessel in an offshore application. In this specification the term “external crane” is used to describe cranes which are not wind turbine mounted cranes. External cranes are sometimes assembled on a crane base foundation arranged on the ground, for example a concrete foundation built on / in the ground. Other examples of external cranes are cranes which are driven or sailed to the wind turbine location.

[0007] Background of the invention

[0008] Tower mountable cranes (TMC) have been used in the past. However, in most cases, the TMCs are used in onshore applications where the wind turbine tower is mounted to a fixed ground foundation where the tower moves less than in offshore applications. Furthermore, often the TMC can be hoisted directly from the ground via a ground-based winch. As such, there is no external crane which moves relative to the tower. Hence, installation in onshore applications is easier and safer.

[0009] Summary of the first invention

[0010] It is therefore a first aspect of the current invention to provide a method and a system for installing a TMC on a tower of a wind turbine which is more suitable for offshore applications. A second aspect of the current invention is to provide a tower mountable crane which is more suitable for offshore applications.

[0011] These aspects are provided by a method for mounting a tower mountable crane (TMC) to a tower of a wind turbine, for example an offshore wind turbine, said tower having a central axis extending along a length of the tower in a vertical direction, said TMC comprising a base portion which is arranged to be connectable to a tower of a wind turbine, a boom having a base end pivotally connected to the base portion and a tip end arranged distally from the base end and a lifting hook connected to a tip end of the boom via a cable controlled by a winch, the method comprising: a. lifting a hoist block and mounting the hoist block to an upper portion of the tower, b. connecting the cable between the TMC and the hoist block such that the cable extends from the TMC to the hoist block and back to the TMC, c. lifting the TMC using a lifting wire of an external crane, d. tensioning the cable extending between the hoist block and the TMC to partially support the TMC via said cable; e. increasing the tension in the cable until the TMC is completely supported by said cable; and f. disconnecting the lifting wire of the external crane from the TMC.

[0012] In some embodiments, the hoist block is lifted using a lifting wire of an external crane. In some embodiments, the cable is installed prior to lifting the hoist block. In some embodiments, the cable is installed after mounting the hoist block to the upper portion of the tower. In some embodiments, the TMC is lifted from a deck of a waterborne vessel. In some embodiments, the boom is connected to the base portion of the TMC so that the boom is pivotable about a vertical axis and / or a horizontal axis when the TMC is mounted on a tower of a wind turbine. It should be noted that the term “cable” and “wire” should be broadly interpreted and include flexible elongated members such as wires, cables, ropes, etc as will be known to the person skilled in the art of cranes. In some embodiments, the winch is attached to the TMC. In some embodiments the winch is located apart from the TMC, for example on the ground or on a platform. In some embodiments, the method includes the steps of: after disconnecting the lifting wire of the external crane from the TMC, lifting the TMC by operating the cable, until the TMC is at a desired position, fastening the TMC to the tower, and tilting the boom of the TMC to position the boom of the TMC in a vertically upward position, wherein at the vertically upward position the tip end of the boom is arranged above the base portion of the TMC.

[0013] In some embodiments, the horizontal distance between the TMC and the tower is controllable by increasing or decreasing the tension on the cable and / or decreasing or increasing respectively a tension of the lifting wire of the external crane.

[0014] In some embodiments, the method includes engaging a sliding element connected to the TMC with an outer surface of the tower before disconnecting the lifting wire of the external crane from the TMC.

[0015] In some embodiments, the sliding element is at least one wheel or roller. In some embodiments, the sliding element is attached to the boom of the TMC. In some embodiments, the sliding element is arranged on a portion of the boom which faces away from the lifting hook of the TMC. In some embodiments, the sliding element is arranged on a portion of the boom which is between the base portion of the TMC and the tip portion of the boom. In some embodiments, the sliding element is located closer to the tip of the boom than the base portion of the TMC. In some embodiments, the method includes engaging a bumper of the TMC with an outer surface of the tower when the TMC is partly supported by the cable and partly supported by the lifting wire of the external crane.

[0016] In some embodiments, the bumper is arranged to allow the base portion of the TMC to displace relative to the tower in a direction which is parallel to the central axis of the tower. In some embodiments, the bumper is provided with sliding elements to allow the bumper to displace relative to the tower. In some embodiments, the TMC and the bumper is provided with a displacement mechanism arranged between the base portion of the TMC and the bumper to allow the bumper to displace relative to the base portion of the TMC.

[0017] In some embodiments, the bumper is movably connected to the base portion of the TMC and arranged to be extended and retracted relative to the base portion in a direction having a vector component which is perpendicular to the central axis of the tower to control the contact of the bumper with the surface of the tower. In some embodiments, the TMC comprises a displacement mechanism to extend and retract the bumper relative to the base portion in a direction substantially perpendicular to a central axis of the tower. In some embodiments, the method comprises the steps of controlling the extension and retraction of the bumper to keep the bumper engaged with the tower even when the external crane is moving relative to the tower.

[0018] In some embodiments, after the bumper is engaged with the outer surface of the tower, the bumper is extended further from the base portion of the TMC to push the TMC away from the outer surface of the tower.

[0019] In some embodiments, the TMC is lifted from the deck with the boom of the TMC arranged in a horizontal position. In some embodiments, when the TMC is resting on the deck prior to being lifted, the boom extends in a direction which would be perpendicular to the central axis of the tower were the base portion of the TMC connected to the tower. In some embodiments, the method further comprises tilting the boom of the TMC to a vertically downward position during lifting of the TMC with the lifting wire of the external crane, wherein in the vertically downward position the tip end of the boom is arranged downwardly of the base portion of the TMC.

[0020] A tower mountable crane (TMC) adapted to be mounted to a tower of a wind turbine, said tower having a central axis extending along a length of the tower in a vertical direction, the TMC comprising a. a base portion; and b. a boom having a base end pivotally connected to the base portion and a tip end arranged distally from the base portion and a lifting hook connected to a tip end of the boom via a cable and where c. the TMC further comprises a bumper movably connected to the base portion and arranged to be displaced between an extended position and a retracted position in a radial direction relative to a central axis of the tower to control a contact of the bumper with the tower and / or a position of the bumper relative to the tower and / or a position of the base portion of the TMC relative to the tower.

[0021] In some embodiments, the TMC includes an actuator connected between the base portion of the TMC and the bumper and configured to displace the bumper between the extended position and the retracted position.

[0022] It should be noted that the current specification discloses multiple inventions which could be the subject of multiple divisional applications. The claim set attached to this specification discloses claims directed to a first invention. Additional inventions are described in the specification via examples defined below. Note that Ex. 1 refers to example 1 , Ex. 2 refers to example 2, etc... Summary of the second invention

[0023] In the prior art type Tower Mountable Cranes (TMCs), the TMC is transferred to the tower in a more precise manner and therefore the connection between the TMC and the tower can be performed more securely. In offshore applications, it is more dangerous to attach a TMC to a tower. Hence, it is a first aspect of the second invention to provide a TMC which is able to connect to a tower in a more secure manner.

[0024] This aspect is provided via a TMC as defined by the examples below.

[0025] Ex. 1 . A tower mountable crane (TMC) adapted to be mounted to a tower of a wind turbine, for example an offshore wind turbine, said tower having a central axis extending along a length of the tower in a vertical direction, the TMC comprising: a. a base portion; and b. a boom having a base end pivotally connected to the base portion and a tip end arranged distally from the base portion and a lifting hook connected to a tip end of the boom via a cable characterized in that c. the TMC further comprises a bumper movably connected to the base portion and arranged to be displaced between an extended position and a retracted position in a radial direction relative to a central axis of the tower to control a contact of the bumper with the tower and / or a position of the bumper relative to the tower and / or a position of the base portion of the TMC relative to the tower. Ex. 2. The TMC according to example 1 , characterized in that the bumper is arranged to be able to slide along the tower when the bumper is in contact with the tower.

[0026] Ex. 3. The TMC according to example 1 or 2, characterized in that the bumper includes at least one wheel or roller adapted to contact the tower and slide along the tower. In some embodiments, the at least one wheel or roller comprises at least a pair of wheels.

[0027] Ex. 4. The TMC according to any one of the preceding examples, characterized in that the TMC includes an actuator connected between the base portion of the TMC and the bumper and configured to displace the bumper between the extended position and the retracted position.

[0028] Ex. 5. The TMC according to example 4, characterized in that TMC includes a. a sensor to detect a movement of the tower relative to the base portion of the TMC in the radial direction relative to the central axis of the tower; and b. a controller connected to the sensor and the actuator and configured to operate the actuator based on input from the sensor to extend and retract the bumper to control the contact of the bumper with the tower. In some embodiments, the TMC comprises sensors to detect a movement of the tower relative to the external crane in the radial direction relative to the central axis of the tower and a controlled connected to the sensor and the actuator and configured to operate the actuate based on input the sensor to extend and retract the bumper to maintain the connection between the bumper and the tower. Ex. 6. The TMC according to any one of the preceding examples, characterized in that the TMC includes a damping mechanism arranged between the bumper and the base portion to dampen the relative motion between the bumper and the base portion in a direction parallel and / or perpendicular to the central axis of the tower. In some embodiments, the damping mechanism is a passive damping mechanism. In some embodiments, the damping mechanism is an active damping mechanism.

[0029] Ex. 7. The TMC according to any one of the preceding examples, wherein the boom is arranged to pivot between a vertically upward position and a vertically downward position, wherein a. in the vertically upward position, the tip end of the boom is arranged upwardly of the base portion, and b. in the vertically downward position, the tip end of boom is arranged downwardly of the base portion. In some embodiments, the angle between a vector joining the tip end and the base end of the boom in the vertically upward position and a vector joining the tip end and the base end of the boom in the vertically downward position is at least 120 degrees, at least 140 degrees or at least 160 degrees.

[0030] Ex. 8. The TMC according to any one of the preceding examples, characterized in that the bumper is arranged to prevent motion of the TMC perpendicular to a plane comprising the central axis of the tower and passing through a centre of the base portion of the TMC.

[0031] Ex. 9. The TMC according to example 8, characterized in that the bumper comprises at least two wheels arranged one on either side of the plane comprising the central axis of the tower and passing through the centre of the base portion of the TMC, when the bumper is engaged with the tower.

[0032] Summary of the third invention

[0033] In the prior art type Tower Mountable Cranes (TMCs), the TMC is transferred to the tower in a more precise manner and therefore the connection between the TMC and the tower can be performed more securely. In offshore applications, it is more dangerous to attach a TMC to a tower. Hence, it is a first aspect of the third invention to provide a TMC which is able to connect to a tower in a more secure manner.

[0034] This aspect is provided via a TMC as defined by the examples below.

[0035] Ex. 11 .A tower mountable crane (TMC) adapted to be mounted to a tower of wind turbine, for example an offshore wind turbine, said tower having a central axis extending along a length of the tower in a vertical direction the TMC comprising: a. a base portion, b. a boom having a base end pivotally connected to the base and a tip end arranged distally from the base, c. and a lifting hook connected to a tip end of the boom via a cable characterized in that d. the TMC includes a bumper connected to the base and arranged to contact an outer surface of the tower and in that the bumper is arranged such that the base portion of the TMC can move relative to the tower along a direction which is parallel to the central axis of the tower, when the bumper is in contact with the tower. Ex. 12. The TMC according to example 11 , characterized in that the bumper includes a sliding mechanism adapted to contact the tower and slide along the tower. In some embodiments, the sliding mechanism comprises at least one wheel or roller. In some embodiments, the sliding mechanism comprises a pair of wheels. In some embodiments, the sliding mechanism comprises a pair of wheels, at least one wheel of the pair of wheels arranged on either side of a plane comprising the central axis of the tower and passing through the centre portion of the TMC when the bumper is in contact with the tower.

[0036] Ex. 13. The TMC according to example 11 , characterized in that the bumper is displaceably connected to the base portion, such that the bumper can displace relative to the base portion along a direction which is parallel to the central axis of the tower when the bumper is in contact with the tower.

[0037] Ex. 14. The TMC according to any one of the examples 11 to 13, characterized in that the bumper is movably connected to the base portion and arranged to be displaced between an extended position and a retracted position in a radial direction relative to the central axis of the tower to maintain a contact of the bumper with the tower.

[0038] Ex. 15. The TMC according to example 14, characterized in that the TMC includes an actuator connected to the base portion and the bumper and configured to displace the bumper between the extended position and the retracted position.

[0039] Ex. 16. The TMC according to example 15, characterized in that the

[0040] TMC includes a. a sensor to detect a movement of the tower in the radial direction relative to the central axis of the tower; and b. a controller connected to the sensor and the actuator and configured to operate the actuator based on input from the sensor to extend and retract the bumper to control the contact of the bumper with the tower.

[0041] Ex. 17. The TMC according to any one of the examples 11 to 16, characterized in that the TMC includes damping means arranged between the bumper and the base portion to dampen relative motion between the bumper and the base portion in a direction parallel to the central axis of the tower.

[0042] Ex. 18. The TMC according to any one of the examples 11 to 17, characterized in that the TMC includes at least one damper arranged between the bumper and base portion to dampen the relative motion between the bumper and the base portion in a direction perpendicular to the central axis of the tower.

[0043] Ex. 19. The TMC according to any one of the examples 11 to 18, characterized in that the boom is arranged to pivot between a vertically upward position and a vertically downward position, wherein a. in the vertically upward position, the tip end of the boom is arranged upwardly of the base portion, and b. in the vertically downward position, the tip end of boom is arranged downwardly of the base portion. In some embodiments, the angle between a vector joining the tip end and the base end of the boom in the vertically upward position and a vector joining the tip end and the base end of the boom in the vertically downward position is at least 120 degrees, at least 140 degrees or at least 160 degrees. Ex. 20. The TMC according to any one of the examples 11 to 19, characterized in that the bumper mechanism is arranged to prevent motion of the TMC perpendicular to a plane comprising the central axis of the tower and passing through the centre of the base portion.

[0044] Summary of the fourth invention

[0045] In the prior art type Tower Mountable Cranes (TMCs), the TMC is transferred to the tower in a more precise manner and therefore the connection between the TMC and the tower can be performed more securely. In offshore applications, it is more dangerous to attach a TMC to a tower. Hence, it is a first aspect of the fourth invention to provide a TMC which is able to connect to a tower in a more secure manner.

[0046] This aspect is provided via a TMC as defined by the examples below.

[0047] Ex. 21 .A tower mountable crane (TMC) adapted to be mounted to a tower of a wind turbine, for example an offshore wind turbine, said tower having a central axis extending along a length of the tower in a vertical direction, the TMC comprising: a. a base portion; b. a boom having a base end pivotally connected to the base and a tip end arranged distally from the base, and c. a lifting hook connected to a tip end of the boom via a cable d. and where the boom is arranged to pivot about a horizontal axis between a vertically upward position and a vertically downward position, wherein in the vertically upward position, the tip end is arranged upwardly of the base portion, while in the vertically downward position, the tip end is arranged downwardly of the base portion, characterized in that e. the TMC includes a sliding element connected to the boom, wherein the sliding element is arranged to contact and slide along an outer surface of the tower when the boom is arranged in the vertically downward position and the TMC is being lifted along the tower.

[0048] Ex. 22. The TMC according to example 21 , characterized in that the sliding element is at least one wheel or roller.

[0049] Ex. 23. The TMC according to example 21 or 22, characterized in that the sliding element comprises at least two wheels, at least one wheel arranged on either side of a plane comprising the central axis of the tower when the sliding element is in contact with the tower.

[0050] Ex. 24. The TMC according to any one of the examples 21 to 23, characterized in that the sliding element is arranged on the side of the boom which is opposite to the lifting hook in the position which the boom would be in when connected to the tower and in the vertically upwards position.

[0051] Ex. 25. The TMC according to any one of the examples 21 to 24, characterized in that the sliding element is arranged between the base end and the tip end of the boom.

[0052] Ex. 26. The TMC according to example 25, characterized in that the sliding element is arranged closer to the tip end than the base end.

[0053] Ex. 27. The TMC according to any one of examples 21 to 26, characterized in that the sliding element is arranged at an offset to a line joining the tip end and the base end of the boom. Ex. 28. The TMC according to example 27, characterized in that the offset is greater than 5% of the length of said line. In some embodiments, the offset is greater than 10%, greater than 15% or greater than 20% of the length of said line.

[0054] Ex. 29. The TMC according to any one of the examples 21 to 28, characterized in that the sliding element is arranged to prevent motion of the boom perpendicular to a plane comprising the central axis of the tower and a centre of the base portion of the TMC. of the fifth invention

[0055] In the prior art type Tower Mountable Cranes (TMCs), the TMC is lifted along the tower via a hoist block which is connected to the top of the tower. In the prior art type systems, the hoist block is able to be installed on the tower in a more precise manner and therefore the connection between the hoist block and the tower can be performed more securely. In offshore applications, it is more dangerous to attach a hoist block to a tower, especially since it needs to be connected to the top of the tower, where the relative motions between the tower and the external crane will be maximized. Hence, it is a first aspect of the fifth invention to provide a hoist block which is able to connect to a tower in a more secure manner.

[0056] This aspect is provided via a hoist block as defined by the examples below.

[0057] Ex. 31. A hoist block for use in a method for lifting a tower mountable crane (TMC) to a tower of a wind turbine, for example an offshore wind turbine, the hoist block comprising: a. a frame, b. a connection element which is connectable to a lifting wire of a crane, and c. at least one tower connection element coupled to the frame and configured to attach the hoist block to the tower, characterized in that d. the hoist block includes a bumper structure connected to the frame, said bumper structure comprising a tower contact surface having at least an upper and a lower portion spaced apart from each other in the vertical direction, said at least upper and lower portions being arranged to contact an outer surface of the tower when the hoist block is being mounted to the tower and when the hoist block is mounted to the tower.

[0058] Ex. 32. The hoist block according to example 31 , characterized in that the bumper structure is arranged below the at least one tower connection element.

[0059] Ex. 33. The hoist block according to example 31 or 32, characterized in that the tower contact surface includes a main contact portion which is arranged to contact an area of the surface of the tower, said main contact portion having a main contact surface with a main contact vector A which is arranged perpendicular to the main contact surface, said bumper structure further comprises a first side contact portion and a second side contact portion, said first side contact portion is arranged to contact another area of the surface of the tower, said first side contact portion being located offset from the main contact surface in a direction both along the main contact vector and to the side of the main contact vector and said second side contact portion being arranged to contact another area of the surface of the tower located offset from the main contact surface in a direction both along the main contact vector ahead and to the opposite side of the main contact portion. In this way, the position of the hoist block can be held in place relative to the tower in a horizontal plane when the bumper structure is in contact with the tower.

[0060] Ex. 34. The hoist block according to example 33, characterized in that the main contact portion, the first side contact portion and the second side contact portion are portions of a curved structure configured to wrap around a portion of the outer surface of the tower.

[0061] Ex. 35. The hoist block according to any one of the examples 31 to 34, characterized in that the hoist block includes a hoist pulley block having at least one sheeve and a cable of the TMC extending around the at least one sheeve to enable the lifting of the TMC. In some embodiments the hoist pulley block comprises at least two, four or eight sheeves. In some embodiments, the hoist pulley block is arranged above the tower connection element.

[0062] Ex. 36. The hoist block according to any one of the examples 31 to 35, characterized in that the at least one tower connection element includes a block extending outwardly of the frame and comprising a downwardly extending protrusion which is adapted to be inserted inside an upwardly open recess of a flange of the tower to engage and secure the hoist block to the tower. In some embodiments, the downwardly extending protrusion is a protruding flange. In some embodiments, the protruding flange is curved in a horizontal plane.

[0063] Ex. 37. Hoist block according to any one of the examples 31 to 36 characterized in that a Centre of Gravity (COG) of the hoist block is arranged such that when the hoist block is hanging from a lifting wire of a crane, the tower contact surface of the bumper structure is arranged such that the lower contact portion will contact the tower surface before or at the same time as the upper contact portion.

[0064] Ex. 38. Hoist block according to example 37, characterized in that the COG of the hoist block is further arranged such that when the upper and lower contact portions of the tower contact surface are engaged with the tower surface, the Centre of Gravity of the hoist block will exert a moment about the upper contact portion which pushes the lower contact portion towards the tower surface.

[0065] Ex. 39. Hoist block according to example 38, characterized in that the moment exerted about the upper contact portion is arranged such that the angle of a lifting wire of a crane lifting the hoist block at the position where the upper and lower contact surfaces first contact the surface of the tower can be increased by at least 2 degrees in a direction towards the centre of the tower without the bottom contact surface leaving the surface of the tower. In some embodiments, the angle of the lifting wire can be increased by at least 3 degrees, at least 4 degrees or at least 5 degrees. nmary of the sixth invention

[0066] In the prior art type Tower Mountable Cranes (TMCs), the TMC is lifted along the tower via a hoist block which is connected to the top of the tower. In the prior art type systems, the hoist block is able to be installed on the tower in a specific position which is typically determined by the installation site and access to the tower. In offshore applications, it is typical that the tower can be approached from many directions. However, the wind in offshore locations can often be stronger than on onshore locations. Furthermore, waves in offshore locations can make hoist block installations more difficult. It is therefore more dangerous to attach a hoist block to a tower, especially since it needs to be connected to the top of the tower, where the relative motions between the tower and the external crane will be maximized. Hence, it is a first aspect of the sixth invention to provide a tower section for a tower which allows a hoist block to connect to the tower in a more secure and a more flexible manner.

[0067] This aspect is provided via a tower section as defined by the examples below.

[0068] Ex. 41. A tower section for a tower of a wind turbine, the tower section comprising: a. a cylindrical body having an upper end and a lower end; and b. a hoist block connection element arranged proximate to the upper end and integrally formed with or fastened to the cylindrical body and extending radially outwardly from an outer surface of the cylindrical body characterized in that c. the hoist block connection element is configured to engage with a tower connection element of a hoist block to secure the hoist block to the tower at different possible positions arranged 360 degrees around a central axis of the tower section.

[0069] Ex. 42. The tower section according to example 41 , characterized in that the hoist block connection element is a flange extending outwardly from the outer surface of the cylindrical body of the tower section.

[0070] Ex. 43. The tower section according to example 41 or 42, characterized in that hoist block connection element includes a groove arranged 360 degrees around a central axis of the tower section. Ex. 44. The tower section according to example 41 or 42, characterized in that the hoist block connection element includes a plurality of recesses, for example holes or slots, arrayed circularly around a central axis of the tower section.

[0071] Ex. 45. The tower section according to any one of the examples 41 to 44, characterized in that the tower section comprises a crane connection element arranged proximate to the upper end and integrally formed with or fastened to the cylindrical body and extending radially outwardly from an outer surface of the cylindrical body, said crane connection element being configured to engage with a tower connection element of a crane to secure the crane to the tower at different possible positions arranged 360 degrees around a central axis of the tower section.

[0072] Ex. 46. The tower section according to example 45 characterized in that the crane connection element and the hoist block connection element are the same element and in that the tower connection element of the crane and the tower connection element of the hoist block engage with the same element at different locations around the central axis of the tower section. of the seventh invention

[0073] In the prior art type Tower Mountable Cranes (TMCs), the TMC is lifted along the tower via a hoist block which is connected to the top of the tower. In the prior art type systems, the hoist block is typically removed at the end of the TMC operation via a small crane on the wind turbine itself. In offshore applications, an external crane can be used to remove the hoist block from the tower. However, due to the position of the hoist block relative to the nacelle of the wind turbine, it is not possible for a lifting wire of an external crane to connect to the hoist block. Hence, it is a first aspect of the seventh invention to provide a method for removing a hoist block from a tower which is able to be used by an external crane when the nacelle is in place at the top of the tower.

[0074] This aspect is provided via a method as defined by the examples below.

[0075] Ex. 51 .A method for removing a hoist block from a tower of a wind turbine having a nacelle mounted on the tower, the method comprising: a. lifting a counterweight tool using an external crane, wherein the counterweight tool includes an elongated portion having a first end and second end, a sliding element attached to the first end of the elongated portion, a connector, for example a hook, connected to a wire attached near the first end of the elongated portion, and a counterweight attached to the second end of the elongated portion, and a connection structure arranged between the first end and the second end, wherein the external crane is connected to the connection structure; b. positioning the connector of the counterweight tool upwardly of the hoist block; c. engaging the connector with the hoist block; d. moving the counterweight tool towards the tower such that the sliding element contacts an outer surface of the tower and e. disengaging the hoist block from the tower by lifting the counterweight tool using the external crane while keeping the sliding element in contact with the tower.

[0076] Ex. 52. The method according to example 51 , characterized in that the method further includes a. moving the hoist block away from the tower by operating the external crane upon disengagement of the hoist block from the tower, and b. lowering the hoist block by lowering the counterweight tool using the external crane upon moving the hoist block away from the tower.

[0077] Ex. 53. The method according to example 51 or 52, characterized in that the counterweight tool is arranged such that when the sliding element is in contact with the tower and the connector is connected to the hoist block, the wire connecting the connector to the elongated portion is arranged at an angle to the vertical.

[0078] Ex. 54. The method according to any one of examples 51 to 53, characterized in that the sliding element is a wheel.

[0079] Ex. 55. The method according to any one of examples 51 to 54, characterized in that the sliding element comprises a shock absorbing element to reduce the force of contact between the sliding element and the tower.

[0080] Ex. 56. The method according to any one of examples 51 to 55, characterized in that the sliding element is arranged to prevent motion of the sliding element relative to the tower in the horizontal plane when the sliding element is in contact with the tower.

[0081] Summary of the eight invention

[0082] In the prior art type Tower Mountable Cranes (TMCs), the TMC is lifted along the tower via a hoist block which is connected to the top of the tower. In the prior art type systems, the hoist block is typically installed via a small crane on the wind turbine itself. In offshore applications, an external crane can be used to install the hoist block on the tower. However, due to the position of the hoist block relative to the nacelle of the wind turbine, it is not possible for a lifting wire of an external crane to connect to the hoist block when the nacelle is present on the top of the tower. Hence, it is a first aspect of the eighth invention to provide a method for installing a hoist block on a tower which is able to be used by an external crane when the nacelle is in place at the top of the tower. This is for example relevant in maintenance / service operations.

[0083] This aspect is provided via a method as defined by the examples below.

[0084] Ex. 61. A method for installing a hoist block on a tower of a wind turbine having a nacelle mounted on the tower, the method comprising: a. engaging a counterweight tool to an external crane, wherein the counterweight tool includes an elongated portion having a first end and second end, a sliding element attached to the first end of the elongated portion, a connector, for example a hook, connected to a wire attached near the first end of the elongated portion, and a counterweight attached to the second end of the elongated portion, and a connection structure arranged between the first end and the second end, wherein the external crane is engaged to the connection structure; b. attaching the connector of the counterweight tool to the hoist block, and lifting the hoist block by operating the external crane; c. positioning the sliding element of the counterweight tool upwardly of a flange of the tower and contacting an outer surface of the tower such that a tower connection element of the hoist block is arranged upwardly of the flange of the tower; d. engaging the tower connection element of the hoist block with the flange by moving the counterweight tool downwardly, keeping the sliding element in contact with the tower; and e. disengaging the connector of the counterweight tool from the hoist block.

[0085] Ex. 62. The method according to example 61 , characterized in that the method further comprises moving the sliding element away from the tower before disengaging the connector from the hoist block.

[0086] Ex. 63. The method according to example 61 or 62, characterized in that the method further includes a. moving the counterweight tool away from the hoist block by operating the external crane upon disengagement of the hoist block from the tower, and b. lowering the counterweight tool by operating the external crane.

[0087] Ex. 64. The method according to any one of examples 61 to 63, characterized in that the counterweight tool is arranged such that when the sliding element is engaged with the tower and the connector is connected to the hoist block, the wire is arranged at an angle to the vertical. of the ninth invention

[0088] In the prior art type Tower Mountable Cranes (TMCs), the TMC is lifted along the tower via a hoist block which is connected to the top of the tower. In the prior art type systems, the hoist block is typically installed and removed via a small crane on the wind turbine itself. In offshore applications, an external crane can be used to install and remove the hoist block on the tower. However, due to the position of the hoist block relative to the nacelle of the wind turbine, it is not possible for a lifting wire of an external crane to connect to the hoist block when the nacelle is present on the top of the tower. Hence, it is a first aspect of the ninth invention to provide a hoist block assembly for installing and / or removing a hoist block on a tower which is able to be used by an external crane when the nacelle is in place at the top of the tower.

[0089] This aspect is provided via a hoist block assembly as defined by the examples below.

[0090] Ex. 71. A hoist block assembly for a tower mountable crane (TMC), the hoist block assembly comprising: a. a hoist block adapted to be mounted to a tower and including a hoist pulley block to receive a cable of the TMC and a connection element arranged proximate to an upper end of the hoist block; and b. a counterweight tool having i. an elongated portion, ii. a sliding element attached to a first end of the elongated portion, iii. a connector attached proximate to the first end of the elongated portion and adapted to be removably engaged with the connection element of the hoist block, iv. a counterweight arranged at a second end of the elongated portion, and v. a connection structure attached to the elongated portion and arranged between the first end and the second end, wherein an external crane is connected to the connection structure to enable a lifting of the counterbalance structure, c. wherein the counterweight tool facilitates an installation and / or removal of the hoist block from the tower using an external crane.

[0091] Ex. 72. The hoist block assembly according to example 71 characterized in that the sliding element is a wheel which is arranged to rotate relative to the elongated portion.

[0092] Ex. 73. The hoist block assembly according to example 71 or 72, characterized in that the counterweight is removably attached to the elongated portion.

[0093] Ex. 74. The hoist block assembly according to any one of the examples 71 to 73, characterized in that the counterweight is integral to the elongated portion.

[0094] Ex. 75. The hoist block assembly according to any one of the examples 71 to 74, characterized in that the counterweight is arranged to slide along a longitudinal axis of the elongated portion between the connection structure and the second end of the lever.

[0095] Ex. 76. The hoist block assembly according to any one of the examples 71 to 75, characterized in that the connector is connected to the elongated portion via an elongated flexible element. Some examples of a suitable elongated flexible element include a wire, cable, sling, rope, chain, etc..

[0096] Ex. 77. The hoist block assembly according to any one of the examples 71 to 76, characterized in that the counterweight is a variable weight counterweight. Ex. 78. The hoist block assembly according to any one of the examples 71 to 77 characterized in that the hoist block further comprises a bumper structure having a tower contact surface, the tower contact surface of the hoist block and the sliding element of the counterweight tool being arranged such that the tower contact surface contacts the tower prior to the sliding element when the hoist block assembly is moved towards the tower. of the tenth invention

[0097] In the prior art type Tower Mountable Cranes (TMCs), the TMC is lifted along the tower via a hoist block which is connected to the top of the tower. In the prior art type systems, the hoist block is typically installed via a small crane on the wind turbine itself. In offshore applications, an external crane can be used to install the hoist block on the tower. However, due to the motion of the external crane relative to the tower, the installation of the hoist block can be more dangerous and difficult. Hence, it is a first aspect of the tenth invention to provide a method of installing a hoist block which allows for a more secure and easy installation of the hoist block on a tower.

[0098] This aspect is provided via a method as defined by the examples below.

[0099] Ex. 81 . Method of installing a hoist block on a tower of a wind turbine, said method comprising the steps of: a. attaching a lifting wire of a crane to a connection element of the hoist block, b. lifting the hoist block via the lifting wire of the crane, c. lifting the hoist block to a position near the top of the tower such that a tower connection element of the hoist block is arranged above a hoist block connection element on the tower and such that the tower connection element is spaced away from the hoist block connection element in the horizontal direction, d. moving the hoist block via the lifting wire of the crane towards the tower until a bumper structure of the hoist block engages with an outer surface of the tower located below the hoist block connection element, e. moving the crane such that the lifting wire forms an angle to the vertical, and f. lowering the hoist block such that the tower engaging portion of the hoist block engages with the hoist block connection element of the tower.

[0100] Ex. 82. Method according to example 81 , characterized in that the tip portion of the crane is moved to a position which is arranged at least 10% of the diameter of the top section of the tower away from the outer surface of the tower towards the centre of the tower.

[0101] Ex. 83. Method according to example 82, characterized in that the tip portion is moved such that the lifting wire lifting the hoist block is arranged at an angle of at least 2 degrees to the vertical.

[0102] Ex. 84. Method according to any one of the examples 81 to 83, characterized in that the bumper structure of the hoist block is arranged to lock the position of the hoist block relative to the tower in a horizontal plane when the bumper structure is in contact with the outer surface of the tower.

[0103] Ex. 85. Method according to example 84, characterized in that the bumper structure of the hoist block is arranged to allow motion of the hoist block relative to the tower in a direction which is parallel to the central axis of the tower when the bumper structure is in contact with the tower.

[0104] Ex. 86. Method according to any one of the examples 81 to 85, characterized in that the centre of gravity of the hoist block is arranged relative to the connection element of the hoist block such that when the hoist block is hanging via the connection element, then the bumper structure will come into contact with the outer surface of the tower before the tower connection element of the hoist block when the hoist block is moved towards the tower.

[0105] Ex. 87. Method according to any one of the examples 81 to 86, characterized in that the centre of gravity of the hoist block is arranged relative to the connection element of the hoist block such that when the hoist block is hanging via the connection element, then a lower portion of the bumper structure will come into contact with the outer surface of the tower before or at the same time as an upper portion of the bumper structure. of the eleventh invention

[0106] In the prior art type Tower Mountable Cranes (TMCs), the TMC is attached to the tower near the top of the tower. In some prior art solutions, the TMC is clamped to a flange. In other cases the TMC is connected to the tower via straps around the surface of the tower. It is a first aspect of the eleventh invention to provide a TMC which connects to the tower in an alternative manner.

[0107] This aspect is provided via a TMC as defined by the examples below. Ex. 91. Tower mountable crane (TMC) comprising a base portion, a first inward tower engaging element, a second inward tower engaging element, a first outer tower engaging element and a second outer tower engaging element, the first and second inward tower engaging elements comprising downwardly extending elements which are arranged to be inserted into an upwardly facing groove of a proximal crane connection element extending from an outer surface of the tower and the first and second outer tower engaging elements comprising upwardly facing engaging elements which engage with a downwardly facing surface of a distal crane connection element of the tower.

[0108] Ex. 92. TMC according to example 91 , characterized in that the first and second outer tower engaging elements are arranged further away from the base portion of the TMC than the first and second inner tower engaging elements.

[0109] Ex. 93. TMC according to any one of the examples 91 to 92, characterized in that the first and second inner tower engaging elements and the first and second outer tower engaging elements are connected to the same crane connection element. In some embodiments, the crane connection element is a flange extending outwardly from the surface of the tower.

[0110] Ex. 94. TMC according to any one of examples 91 to 93, characterized in that the TMC comprises a first arm extending outwardly from the base portion and a second arm extending outwardly from the base portion, the first inner tower engaging element being connected to the first arm and the second inner tower engaging element being connected to the second arm. Ex. 95. TMC according to example 94, characterized in that the first arm is pivotably connected to the base portion about a first vertical axis and the second arm is pivotably connected to the base portion about a second vertical axis.

[0111] Ex. 96. TMC according to example 94 or 95, characterized in that the TMC comprises a third arm and a fourth arm, said first outer tower engaging element being connected to the third arm and the second outer tower engaging element being connected to the fourth arm.

[0112] Ex. 97. TMC according to example 96, characterized in that the third arm is connected to the first arm and the fourth arm is connected to the second arm.

[0113] Ex. 98. TMC according to example 97, characterized in that the third arm is pivotably connected to the first arm about a third vertical axis and the fourth arm is pivotably connected to the second arm about a fourth vertical axis.

[0114] Ex. 99. TMC according to any one of the examples 91 to 98, characterized in that the TMC is arranged to be pivotable about a horizontal axis relative to the tower when supported by the cable of the TMC, such that TMC can be arranged in a first position where the first and second inner engaging elements are arranged above the proximal crane connection element of the tower and the first and second outer engaging elements are arranged below the distal crane connection element of the tower and in a second position where the first and second inner engaging elements are engaging an upper surface of the proximal crane connection element of the tower and where the first and second outer engaging elements are engaging a lower surface of the distal crane connection element. It should be emphasized that the term "comprises / comprising / comprised of" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0115] It should also be noted that the numbering of the features in the product claims / examples and the numbering of the steps in the method claims / examples do not indicate a defined order of the features or steps unless specifically mentioned, but are just used to format the claims / examples and make the features / steps easily identifiable.

[0116] Brief description of the drawings

[0117] In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

[0118] Figure 1 shows a perspective view of a step in a process of mounting a TMC to a tower of an offshore wind turbine, where a hoist block is lifted by using an external crane proximate to an upper portion of the tower to connect the hoist block to the tower, the external crane and the cable of the TMC is removed for simplicity.

[0119] FIG. 2 shows a side view of a step of the process where the hoist block is mounted to a flange of the tower and the cables extend downwardly from the hoist block. Figure 3 shows a sectional side view of the upper portion of the tower depicting the flange having a groove as a hoist block connection element and extending 360 degrees around a central axis of the tower.

[0120] Figures 4-6 show sectional side views of portion of the tower and a portion of the hoist block depicting relative positioning of the tower connection element of the hoist block and the hoist block connection element of the tower during connection of the hoist block with the tower.

[0121] Figure 7 shows a side view of a further step in the process of mounting the TMC to the tower, where the TMC is lifted from a deck of a waterborne vessel via an external crane with boom arranged at a horizontal position.

[0122] Figure 8 shows a side view of another step where the boom of the TMC is tilted downwardly of a base portion of the TMC with the weight of the TMC fully supported on the external crane.

[0123] Figure 9 shows a side view of another step where the boom of the TMC is further tilted to move the boom to a vertically downward position while the TMC is fully supported on the external crane.

[0124] Figure 10 shows a side view of another step where a small part of the weight of TMC is supported on the TMC’s own cable and the remaining weight of the TMC is supported on the external cable.

[0125] Figure 11 shows a side view of another step where a major part of the weight of the TMC is supported on the TMC’s own cable and remaining weight is supported on the external crane, where the tower is arranged between the two arms of the TMC and a bumper of the TMC is engaged with the tower. Figure 12 shows a side view of another step where the TMC is fully supported on the TMC’s own cable and the boom is further tilted downwardly to engage a sliding element of the TMC with an outer surface of the tower before disconnecting the external crane from the TMC.

[0126] Figure 13 shows a top view of the TMC with arms arranged around the tower and disengaged from the tower and the bumper arranged in a retracted position.

[0127] Figure 14 shows a top view of the TMC with bumper arranged in contact of the outer surface of the tower and disposed in an extended position, where the bumper is engaged with the tower before fully supporting the TMC on its own cable.

[0128] Figure 15 shows a top perspective view of the TMC arranged supported on its own cables and the boom arrange in a horizontal orientation depicting various components of the TMC.

[0129] Figure 16 shows an enlarged view of a portion of the TMC of figures 9-15 with tower removed and depicting the structural details of the bumper of the TMC.

[0130] Figure 17 shows an enlarged perspective view depicting the hoist block connected to an upper portion of the tower, the TMC arranged above the deck and supported on its own cable as well as the external crane with the boom of the TMC disposed at the vertically downward position.

[0131] Figure 18-22 show various steps of a process of removal of the hoist block using a counterweight tool from the tower with a nacelle mounted on top of the tower. Figure 23 shows a perspective view of the TMC located near the top of the tower, ready to be connected to the crane connection flange of the tower.

[0132] Figure 24 shows a closeup view of the clamps of one of the arms of the TMC as defined by the circle marked with XXIV in figure 23.

[0133] Figure 25 shows a side view of the TMC with one arm and the tower section removed.

[0134] Figure 26 shows a perspective view showing the inner clamping mechanisms of the TMC engaged with the crane connection flange of the tower.

[0135] Figure 27 shows a perspective and partial cross sectional view of the inner clamping mechanism engaged with the crane connection flange of the tower.

[0136] Figure 28 shows a perspective view showing both the inner and outer clamping mechanisms of the TMC engaged with the crane connection flange of the tower.

[0137] Figure 29 shows a perspective and partial cross-sectional view of the outer clamping mechanism engaged with the crane connection flange of the tower.

[0138] Detailed description of the embodiments

[0139] Figures 1 to 29 show various details of a tower mountable crane (TMC) 100 as well as various steps of a method for mounting a TMC 100 to a tower 200 of an offshore wind turbine. It should be noted that in the current specification, the embodiments are described in an offshore setting where the current inventions are especially suitable, however, the inventions according to the current specification can also be used in non-offshore applications. In the current embodiment, the tower 200 is a tower of an offshore wind turbine mounted to a seabed or floating on a platform in a manner which is known in the art. A base of the tower 200 is typically bolted to a foundation element (not shown) as is known in the art with an upper portion of the tower extending upwardly from the sea surface. In certain cases, the wind turbine tower comprises a single tower section. In other cases, a first tower section is erected on the foundation element in an initial operation, after which one or more additional tower sections are mounted on top of the first tower section. In the current embodiment, the tower comprises a main tower section and a shorter tower section mounted on top of the main tower section.

[0140] When the tower is fully erected, a nacelle is placed on top of the uppermost tower section and then the rotor with the hub and blades are installed as is known in the art. When using a tower mountable crane, the first tower section is erected via an external crane. Then a TMC is typically transferred to the tower section via the external crane so that the TMC can lift the additional tower sections (if any), the nacelle and the rotor into position. The use of a TMC for lifting components, both in an installation operation or a maintenance / service operation is known in the art and will not be described in detail in this specification. This specification is mainly related to the method of transferring the TMC to and from the tower of the wind turbine.

[0141] The first step of installing the TMC, is to install a hoist block near the top of the tower. The hoist block 300 is lifted to the top of the tower 200 via an external crane and connected to a flange near an upper portion 202 of the tower 200, as shown in FIG. 1 and FIG. 2. For lifting the hoist block 300, the hoist block 300 comprises a connection element 301 which is connected to a lifting wire 402 of an external crane 400 arranged on an offshore vessel and then lifted by operating a winch of the external crane 400. As the wind turbine is an offshore turbine, the tower 200 is mounted on the seabed or floating on a floating platform, and extends upwardly away from the seawater surface. Due to the waves of the sea as well as the wind, the tower 200 as well as the external crane 400 can move back and forth and / or up and down. Since the tower and the external crane are independent structures, during installation and removal of the hoist block 300, the tower and the external crane can move relative to each other and therefore the hoist block 300 may also move relative to the tower during the lifting operation. Due to this relative movement, if unchecked, the hoist block 300 may hit the tower 200 repeatedly during installation and removal which not only may damage the tower 200, but also creates challenges in mounting the hoist block 300 to the tower 200. The same issues occur when removing the hoist block 300 from the tower 200 at the end of the TMC operation. To counter this, the hoist block comprises a bumper structure 350 as described in more detail below.

[0142] As shown in figures 1 and 2, the hoist block 300 includes a frame 352 having an upper end 354 and a lower end 356, and at least one tower connection element 310 connected to the frame 352 and arranged between the upper end 354 and the lower end 356 of the frame. In the current embodiment, the tower connection element 310 includes at least one curved block 312 attached to the frame 352 and extending outwardly of the frame 352. The curved block comprises a downwardly extending curved projection 313 which is arranged to engage with an upwardly open curved groove 210 of a flange 202 connected to the upper portion of the tower. The hoist block also comprise a hoist pulley block 304 arranged proximate to the upper end 354 and above of the tower connection element 310. The hoist pulley block is connected to cables 102 which are connected to the TMC and are used to lift the TMC to the upper portion of the tower later on in the procedure. To protect the tower 200 and the hoist block 300 from the above described impacts, to make installation of the hoist block easier and to provide extra support during the lifting of the TMC as described later on, the hoist block 300 includes a bumper structure 350 arranged at a lower portion of the hoist block 300 below the tower connection element 310 of the hoist block 300. The bumper structure comprises a stiff frame structure covered by a relatively soft covering material which is in contact with the tower surface. The soft covering material is a pliable material known in the art which can absorb the forces and distribute them over a larger area.

[0143] In the embodiment, the bumper structure 350 and the at least one tower connection element 310 are arranged on the same side of a vertical plane passing through the connection element 301 when the hoist block is hanging from the external crane. The bumper structure 350 includes a curved portion 360 configured to wrap around a curved outer surface 208 of the tower 200, as shown in FIG. 2. In the illustrated embodiment, the bumper structure 350 includes an upper C shaped member 362 and a lower C shaped member 364 arranged vertically offset from each other and connected to the frame 352. A plurality of vertically extending rods 366 are connected to and extend between the two C-shaped members 362, 364. The C-shaped members 362, 364 are arranged to wrap around an arcuate portion of the outer surface 208 of the tower 200. The vertically extending rods 366 form a tower contact surface. As mentioned above, the tower contact surface is covered with a soft pliable material to reduce the effect of impact of the hoist block 300 with the tower 200.

[0144] Due to the shape of the bumper structure which wraps around the tower, when the tower contact surface of the bumper structure is in contact with the tower surface, the hoist block 300 is secured with respect to the tower 200 in a horizontal plane. In more detail, the C-shaped form of the bumper structure comprises a central portion 370 which will absorb most of the loads between the tower surface and the bumper structure. The bumper structure also has two side portions 372 which will engage with side portions of the tower surface which are arranged on either side of the central portion of the bumper structure. The side portions 372 will absorb forces acting to move the hoist block sideways with respect to the tower and thereby lock the hoist block in the sideways direction.

[0145] The hoist block is lifted by an external crane via a lifting wire 303 connected to a connection element 301 on the hoist block. The hoist block should be arranged such that when the hoist block is hanging freely from the lifting wire, the tower contact surface of the bumper structure is arranged parallel to or slightly tilted away from the tower surface such that the upper portion of the tower contact surface is slightly further from the tower surface than the lower portion of the tower contact surface. In this way, as the hoist block is moved towards the tower, a lower portion of the bumper structure will engage with the tower surface first. The external crane is then moved further in over the tower such that the lifting wire is arranged at a slight angle to the vertical (for example 5 degrees) with the top of the lifting wire being closer to the centre of the tower than the connection element 301 of the hoist block. In this way, the upper portion of the hoist block is pushed more towards the tower until the entire tower contact surface of the hoist block is engaged with the tower surface. The hoist block will then be fully locked in position in the horizontal plane, and further motion of the external crane in the horizontal plane will not cause any motion of the hoist block in the horizontal plane.

[0146] In the shown embodiment, the hoist block is arranged such that the tower contact surface is arranged essentially vertically when the hoist block is hanging freely from the lifting wire of the external crane. Since the tower section typically tapers slightly, when the bumper structure approaches the tower section, a lower portion of the bumper structure will contact the tower surface first, as also described above. It should be noted that the angle of the tower contact surface of the bumper structure is determined by the Centre of Gravity (COG) (357) of the hoist block relative to the connection element 301 of the hoist block. The COG of the hoist block in the current embodiment can be tuned via a counterweight element 358 attached to a lower portion of the frame element. The counterweight element can be moved to different locations and / or the weight of the counterweight element can be changed to ensure that the tower contact surface of the bumper structure has the desired angle.

[0147] The hoist block is furthermore arranged such that when bumper structure is in full contact with the tower surface, the tower connection element of the hoist block will be arranged above the flange of the tower. The external crane can then lower the hoist block slowly and the bumper structure will slide along the tower surface until the tower connection element engages with the flange on the tower.

[0148] It should also be noted that when the hoist block is in place and when tension is applied to the cables connected to the hoist block, a moment will be applied to the hoist block about the tower connection element of the hoist block since the cables are attached to the hoist block above the tower connection element. Without any counter forces, the hoist block would rotate about the tower connection element in a clockwise direction in the orientation shown in the figures. The necessary counter forces are provided by the bumper structure which is designed to be pressed up against the outer surface of the tower to hold the hoist block in place without damaging the outer surface of the tower. Due to the large surface area of the bumper structure, the forces are distributed over a large area of the tower surface.

[0149] Once the hoist block is in place on the tower, a TMC can lift itself up via cables connected between the hoist block and the TMC. In this embodiment a TMC is provided with two parallel wire systems, one connected to the left side of the TMC and one connected to the right side of the TMC. Likewise, the hoist block has two wire systems, one on the left side and one on the right side of the hoist block. However, it will be clear to the person skilled in the art of cranes, that in some cases, a TMC could be provided with only a single wire system.

[0150] It should also be noted that in the current embodiment the cable 102 of the TMC 100 is connected to the hoist block 300 before lifting the hoist block 300. In this case, during lifting of the hoist block 300, at least one winch 104 associated with the cable 102 is operated in accordance with the lifting of the hoist block 300 such that the cable 102 remains slack as the hoist block is lifted. In another embodiment, the winch 104 is freewheeled so that the cable 102 is pulled out of the winch 104 during the lifting motion of the hoist block 300. In other embodiments, not shown, the cable(s) 102 of the TMC 100 could be connected to the hoist block 300 after mounting the hoist block 300 to the upper portion 202 of the tower 200. In such a case, the cables could be lifted to the hoist block using the external crane.

[0151] In this embodiment, the cable 102 is connected to the hoist block 300 by routing the cable 102 from the at least one winch 104 of the TMC 100 to at least one sheave 302 of the hoist pulley block 304 and then back to a pulley system (not shown) mounted to a base portion 110 of the TMC 100. The cable 102 then runs from the pulley system up to a boom 112 of the TMC 100 and to a lifting hook 114. Many different options of routing the cable are possible. One example embodiment of a routing of the cable 102 and pulley system of the TMC 100 is explained in detail in applicant’s co-pending application (PCT / EP2024 / 061324). In the prior application, the cables are connected to ground based cable drums, while in this particular embodiment, cable drums are arranged on the base portion 110 of the TMC 100 itself. However, the basic wire routing is similar in the prior art application and in the current embodiment.

[0152] In the illustrated embodiment, the at winches 104 are mounted to the base portion 110 of the TMC 100. However, it may be appreciated that at least one winch 104 may be arranged on a deck of a waterborne vessel or a ground surface as in applicant’s co-pending application. The free end of the cable 102, after passing through the winch 104 is rolled up onto at least one cable drum (not shown in the current figures).

[0153] To facilitate the mounting of the hoist block 300 and the TMC 100 to tower 200, the tower 200 includes a crane connection flange 202, shown in FIG. 1 and FIG. 2, arranged proximate to a top end of the tower 200 and integrally attached to a cylindrical body 204 of the tower 200. In this embodiment, the crane connection flange is arranged spaced apart from the top of the tower. In this way, the TMC can be connected to the crane connection flange and a nacelle of the wind turbine can be connected to a nacelle connection flange arranged at the top of the tower.

[0154] The crane connection flange 202 extends circularly around a central axis 206 of the tower 200 and extends radially outwardly of an outer surface 208 of the cylindrical body 204 of the tower. The flange 202 includes a hoist block connection element 210, best shown in FIGS. 3 to 6, to receive and engage with at least one tower connection element 310, shown in FIGS. 4 to 6, of the hoist block 300. In the embodiment shown in figures 3 to 6, the hoist block connection element 210 is a groove 212 extending from an upper surface of the flange 202 towards a lower surface of the flange 202, and arranged circularly around the central axis 206 the tower 200, while the tower connection element 310 on the hoist block 300 is a block 312 having a downwardly extending curved flange adapted to extend inside the groove 212. As the hoist block connection element 310 is arranged 360 degrees around the central axis 206 of the tower 200, there is no need for positioning the hoist block 300 and the tower connection element 310 at a certain predefined location around the tower 200, rather the hoist block 300 can be positioned at any location around the tower 200. The position can therefore be chosen depending on wind direction, wind speed, wave characteristics, etc.

[0155] In other embodiments, the hoist block connection element 210 may include a plurality of grooves arrayed circularly around a central axis of the flange 202 and extending through the thickness of the flange 202. In other embodiments, the hoist block connection element 210 may include a plurality of pins arrayed circularly around the central axis of the flange and the tower connection element 310 could include at least one hole to receive the at least one pin to engage the hoist block 300 with the flange 202 of the tower 200.

[0156] In the current embodiment, for connecting the hoist block 300 to the tower 200, the curved flanges 312 are inserted inside the groove 212 of the flange 202, as shown in FIGS. 4 to 6. After mounting the hoist block 300 to the tower 200 and connecting the cable 102 to the hoist block 300, the lifting wire 402 of the external crane 400 is attached to the TMC (TMC) 100, and the TMC 100 is lifted from the deck of the waterborne vessel by operating the external crane 400.

[0157] In this embodiment, referring to FIGS. 13 to 17, the TMC 100 comprises a base portion that includes a first base 122, a second base 124 that is rotatably connected to the first base 122 and configured to rotate about a vertical axis relative to the first base 122 (when the TMC is connected to the tower), and a third base 126 pivotally connected to the second base 124 about a horizontal axis. To pivot the third base 126 relative to the second base 124, the TMC 100 includes a first hydraulic cylinder 128 arranged connected to the second base 124 and the third base 126. The details of the base portion 110 of the TMC 100 are not discussed in the specification as the base portion 110 is similar to the base portion of applicant’s co-pending application (PCT / EP2024 / 061327).

[0158] Further, the TMC 100 includes two arms 130, 132 pivotably connected to the base portion 110 i.e. , the first base 122. The two arms 130, 132 are arranged to pivot around vertical axes so that they can be pivoted into connection with the crane connection flange 202 on the tower 200or pivoted away from the tower 200 to release the TMC 100 from the tower 200. The arms 130, 132 are provided with flange engaging elements 134 which secure the arms 130, 132 with the flange 202 on the tower 202 to thereby securely mount the TMC 100 to the tower 200. The details of the arms 130, 132 and the clamps 134 are discussed in a bit more detail in this specification with regards to Figures 23-25 below. However, it should be noted that many of the inventions claimed in this application are not dependent on the type of connection between the tower 200 and the TMC 100. Applicant’s co-pending application PCT / EP2024 / 061324 discloses details of an alternative suitable mechanism for securing the arms of the TMC to a flange on a tower.

[0159] The TMC 100 further comprises a boom 112 including a lower / bottom portion 140 pivotally connected to the base portion 110 i.e., second base 124 and a tip portion 142 arranged distally from the base portion 110 of the TMC 100. The second base portion is pivotably connected to the base portion about a vertical axis (when the TMC is attached to the tower). A second hydraulic cylinder 144 is connected to the boom 112 and the third base 126 to pivot the boom 112 about a horizontal axis 146. More details of the TMC are provided in applicant’s co-pending application PCT / EP2024 / 061324. Accordingly, by operating the first and second hydraulic actuators / cylinders 128, 144, the boom 112 can be pivoted between a vertically upward position and a vertically downward position. In the vertically downward position, the tip portion 142 is arranged below the base portion 110 of the TMC 100, and a vector connecting a lower end of the lower portion 140 of the boom 112 and an outer end of the tip portion 142 of the boom 112 forms an angle, in a vertical plane, of more than 80 degrees relative to a horizontal axis arranged in the vertical plane and passing through the base portion 110. In the vertically upward position, the tip portion 142 is arranged above the base portion 110 of the TMC 100, and the vector connecting the lower end of the lower portion 140 of the boom 112 and the outer end of the tip portion 142 of the boom 112 forms an angle, in the vertical plane, of more than 80 degrees relative to the horizontal axis passing through the base portion 110. It should be noted that these angles are defined when the base portion 110 is in the orientation which would be its normal operating position when the TMC 100 is mounted to the tower 200. The lifting hook 114 is displaceably connected to the tip portion 142 of the boom 112 via a cable and is configured to facilitate a lifting of a load by the TMC 100.

[0160] Furthermore, the TMC 100 in this embodiment also comprises a cable and pulley system (not shown) comprising at least two cables and a number of pulleys. The cable and pulley system has two purposes. The first purpose is to act as a lifting system to lift loads with the TMC 100 via the lifting hook 114 when the TMC 100 is in its operating position. The second purpose is to lift the TMC 100 itself so that the TMC 100 can move up and down the tower 200. The cable 102 is mainly controlled via the winches 104 mounted to the base portion 102. The wire and pulley system is not discussed in detail in the specification, and is similar to the co-pending application (PCT / EP2024 / 061327) of the same applicant.

[0161] Figures 7-12 show further steps in the mounting procedure. To simplify the drawings, only a single cable is shown extending between the hoist block and the TMC. In real life, there will be a left and a right cable system and each cable system will have multiple wires running back and forth between the hoist block and the TMC as will be known to the person skilled in the art. To transport the TMC 100 on the deck of the waterborne vessel, the boom 112 is arranged in a substantially horizontally position, as shown in FIG. 7. Accordingly, when the TMC 100 is lifted from the deck, the boom 112 is initially arranged in a horizontal position or orientation. However, the TMC 110 may be lifted from the deck with the boom 112 arranged in another orientation if desired.

[0162] During lifting of the TMC 100 from the deck, the boom 112 is pivoted relative to the base portion 110 and is moved to the vertically downward position, as shown in FIGS. 8-9. The tilting of the boom 112 downwardly of the base portion 110 is performed to arrange a centre of gravity of the TMC 100 below the base portion 110 to stabilize the TMC 100 during lifting. Upon lifting the TMC 100 to an appropriate height, the external crane moves the TMC closer to the tower either by moving the external crane and / or moving a vessel on which the external crane is arranged. When the TMC is close to the tower, but not yet in contact with the tower, the winch 104 of the TMC is operated to apply tension to the cable 102 such that a portion of the weight of the TMC 102 is supported by the TMC’s own cable 102, while the remaining portion of the weight of the TMC 100 is still supported by the lifting wire of the external crane 400, as shown in FIG. 10. Subsequently, the tension of the TMC’s own cable 102 is increased gradually, thereby transferring more and more of the TMC’s weight to the TMC’s own cable 102, thereby causing the tension of the lifting wire 402 of the external crane 400 to decrease gradually. As the tension of the cable 102 is increased and / or the tension in the lifting wire 402 of the external crane 400 is decreased, a horizontal distance between the base portion 110 of TMC 100 and the outer surface 208 of the tower 200 is decreased, as shown in FIGS. 10 and 11.. In this scenario, the horizontal distance between the base portion 110 of the TMC 100 and the outer surface 208 of the tower 200 is reduced so much that the arms 130, 132 of the TMC 100 are arranged around the tower 200 with the tower 200 arranged between the pair of arms 130, 132, as shown in FIGS. 13 and 14. It may be noted that during lifting of the TMC 100, the arms 130, 132 remain away from the outer surface 208 of the tower 200 and remains disengaged from the tower 200.

[0163] When the TMC is arranged a slight distance from the tower, and while some of the load of the TMC is still supported by the lifting wire of the external TMC, a bumper 150 of the TMC 100 is extended away from the TMC and engaged with an outer surface of the tower 200 to secure and provide a support to the TMC 100, as shown in FIG. 14. Referring to FIGS. 13, 14, and 16, the bumper 150 is connected to the base portion 110 i.e., the first base 122, and is arranged between the pair of arms 130, 132. In the embodiment, shown in FIGS. 13, 14, and 16, the bumper 150 includes a body portion 152 attached to the first base 122 and extending outwardly from the first base 122 in a direction of the extension of the arms 130, 132 from the base portion 110. As shown, the body portion 152 is arranged between the two arms 130, 132 and includes a pair of elongated rods 154, 156 extending in the direction of extension of the arms 130, 132 from the base portion 110 i.e., the first base 122, and arranged spaced apart from each other. Moreover, the body portion 152 includes a cross-rod 158 extending between the two elongated rods 154, 156 and connected to the elongated rods 154, 156. As shown, the cross-rod 158 is arranged inwardly of the free ends of the elongated rods 154, 156. Further, the bumper 150 includes a pair of wheels 160, 162 attached to the free ends of the elongated rods 152, 154. The wheels 160, 162 are arranged to contact the outer surface 208 of the tower 200 and slide along the outer surface 200 in a direction substantially parallel to the central axis 206 (i.e., longitudinal axis 206) of the tower 200.

[0164] Further, the bumper 150 is movably coupled to the base portion 110 of the TMC 100, and is arranged to extend and retract relative to the base portion 110 along a direction substantially perpendicular to the longitudinal axis 208 of the tower 200. Accordingly, by extending and retracting the bumper 150, the bumper 150 can be moved towards the tower 200 or away from the tower 200. In this embodiment, as the weight of the TMC 100 supported by the cable 102 is gradually increased while decreasing the weight of the TMC 100 supported by the external crane 400, the TMC 100 moves towards the tower 200. However, when the TMC is arranged at a close, but still safe distance from the tower, the motion of the TMC is stopped and the bumper 150 is slowly extended away from the base portion of the TMC by actuating an actuator 164, for example, the hydraulic cylinder, that enables extension and retraction of the bumper 150 relative to the base portion. The bumper is then pushed into the tower 200 such that the bumper contacts the outer surface 208 of the tower 200 in a controlled manner, as shown in FIG. 14.

[0165] Upon contact of the bumper 150 with the tower 200, the TMC 100 is pushed outwards by extending the bumper 152 relative to the base portion 110 even more. As the bumper pushes the TMC outwards away from the tower, the cable of the TMC and the lifting wire of the external crane will pivot outwardly, thereby creating a force which pushes the TMC 100 into the tower 200 via the bumper 152. Therefore, the motions of the external crane 400 in the horizontal plane are not transferred to the TMC 100 in the same way as before. In some embodiments, the TMC 100 may include a sensor that may be connected to the tower 200 and / or the TMC 100 to determine the first contact of the bumper 150 with the tower 200, and accordingly a controller of the TMC 100 may operate the actuator 164, based on input received from the sensor, to extend the bumper to suitably position the base portion 112 from the tower and operate the bumper 150 to maintain the contact of the bumper 152 with the tower 200 depending upon the oscillation of the external crane 400.

[0166] In other embodiments, the extension and retraction of the bumper 152 helps in keeping the bumper 152, i.e. , the wheels 160, 162 engaged with the tower 100 and prevents the disengagement of the bumper 150 due to small movements of the tower 100 and / or the TMC 100 due to sea waves and / or wind.

[0167] FIG 12. shows a further step in the mounting procedure. In this step, the load supported by the lifting wire of the external crane is reduced even further. This causes the TMC to tilt about the connection between the bumper mechanism and the tower, thereby causing the boom 112 to pivot further towards the surface of the tower thereby engaging a sliding element 170 attached to the boom 112 with the outer surface 208 of the tower 200. In this embodiment, the pivoting of the boom is provided by transferring the weight of the TMC from the external crane more to the TMC’s own cables. However, in another embodiment, the pivoting could also be provided by activating the hydraulic cylinders of the boom itself. The sliding element 170 is arranged on a side of the boom 112 that is opposite to that of the lifting hook 114. In this embodiment, the sliding element 170 is a wheel 172 that slides or rolls against the outer surface 208 of the tower 200. The sliding element 170 exerts a force on the tower 200 which in turn helps in reducing the movements of the TMC 100 relative to the tower due to wind acting on the TMC or other tower motion due to wind or waves as the TMC 100 is further lifted using the cable 102.

[0168] Once the sliding element of the boom is engaged with the tower surface, the tension in the lifting wire of the external crane is further reduced, such that entire weight of the TMC is supported by the TMC’s own cable. During this weight transfer, the base portion 112 will move away from the tower 200, causing the disengagement of the bumper 150 from the tower 200. Upon disengagement of the bumper 150 from the tower 200 the bumper 152 is fully retracted into the base portion of the TMC.

[0169] Upon fully supporting the TMC 100 on the TMC’s own cable 102 and connecting the sliding element 170 with the outer surface 208 of the tower 200, the external crane 400 is disconnected from the TMC 100, and the TMC 100 is further lifted to the desired position by operating the winch 104 of the TMC. Once the base portion 112 reaches the desired position i.e., proximate to the crane connection flange near the top end of the tower 200, the arms 130, 132 are secured to the flange 202 of the tower 200 by rotating / pivoting the arms 130, 132 inwardly towards the tower 200 relative to the base portion 112. This is described in more detail with respect to figures 19-22.

[0170] Upon engaging the arms 130, 132 with the tower 200 to secure the TMC 100 to the tower 200, the boom 112 is moved to the vertically upward position such that the tip end 142 of the boom 112 is arranged above the base portion 110.

[0171] The TMC 100 has now been moved to the top of the tower 200 and is firmly connected to the tower 200 via the arms 130, 132. Thereafter, various components of the wind turbine such as, nacelles hubs, blades, etc. are lifted and installed with the help of the TMC 100. Upon completion of mounting and installing the components of the wind turbine, the TMC 100 is lowered back to the vessel in a similar, but reversed procedure. For so doing, the boom 112 is first pivoted to the vertically downward position relative to the base portion 110 with the arms 130, 132 of the TMC 100 being still engaged to the tower 200. Subsequently, the arms 130, 132 are pivoted out relative to base portion 110 to disengage the arms 130, 132 from the tower 200. In this position, the TMC 100 is supported by the cable 102 only. To lower the TMC the winch 104 is operated.

[0172] Once the TMC 100 is lowered a certain amount, the external crane 400 connects to the TMC 100. As the tension in the lifting wire of the external crane is increased, the TMC will start to pivot such that the base portion comes closer to the tower section. At this point, the bumper 150 is extended such that it engages with the tower 200. As the external crane takes more of the load of the TMC, the base portion will be pressed more into the tower and the boom of the TMC will slowly move away from the tower 200. As the TMC 100 is more fully supported by the external crane 400, the base portion of the TMC 100 will move away from the tower. When the TMC is spaced away from the tower, the bumper portion can be retracted and the TMC can be lowered to the vessel.

[0173] Once the TMC 100 is secured on the vessel, the hoist block 300 can be removed by the external crane 400. Due to the presence of the nacelle, it is not possible for the external crane 400 to easily get into contact with the hoist block 300, since the hoist block will be arranged underneath the nacelle, close to the tower surface. As such, a counterweight tool 500 is used to remove the hoist block 300. This is described in more detail below.

[0174] Referring to FIGS. 18-22, a method for removing the hoist block 300 from the tower 200 after attaching the nacelle to the tower 200 of the wind turbine is now described. For removing the hoist block 300 from the tower 200, the counterweight tool 500 is lifted from the ground using the external crane 400. As shown in FIGS. 18-22, the counterweight tool 500 includes an elongated portion 502 having a first end 504 and second end 506, a wheel 508 attached to the first end 504, a hook 510 connected to a wire 512 attached near the first end 504, and a counterweight 514 attached to the second end 506. Moreover, the counterweight tool 500 includes a connection structure 520 arranged between the first end 504 and the second end 506. The lifting wire 402 of the external crane 400 is connected to the connection structure 520 to lift the counterweight tool 500. A weight of the counterweight 514 attached to the second end 506 of the elongated portion 502 is selected such that a moment about the connection structure 520 due to the counterweight 514 is balanced by a moment created by the hoist block 300 about the connection structure 520 when the counterweight tool is lifting the hoist block. Accordingly, depending upon the weight of the hoist block 300, the weight of the counterweight 514 is adjusted.

[0175] It may be noted that the during the lifting of the counterweight tool 500 using the external crane 400, before the hoist block is being lifted, the elongated portion 502 is tilted from a horizontal position with the hook 510 being arranged above the connection structure 520 and the counterweight 514 being arranged below the connection structure 520, see FIG. 19. The counterweight tool 500 is then lifted such that the hook 510 is arranged proximate to the tower 200 and the counterweight 514 is arranged distally to the tower 200 in the horizontal direction.

[0176] After suitably lifting the counterweight tool 500 via the external crane and positioning the hook 510 and the wheel 508 above the hoist block 300, as shown in FIG. 20, the external crane 400 is operated to move the counterweight tool 500 towards the tower 200 in the horizontal direction. As the hook 510 is positioned more forward than the wheel, the hook will be arranged above the connection element 301 of the hoist block before the wheel contacts the tower surface. The hook is then engaged with the hoist y lowering the counterweight tool. The structure of the connection element 301 is such that as the hook 510 is moved downwardly and contacts the connection element of the hoist block 300, the engagement structure 300 securely engages with the hook 510. It may be noted that the engagement structure is a quick connect coupling known in the art. The engagement structure can be remotely controlled, as is known in the art of crane connections. The external crane then moves the counterweight tool more towards the tower and the wheel 508 is positioned such that it is contacting the outer surface 208 of the tower 200 while still being arranged above the hoist block 300, as shown in FIG. 21. It should be noted that as before, the wire which is lifting the hoist block is again arranged at a slight angle to the vertical (in this case 5 degrees) to push the hoist block in towards the tower. When the wheel contacts the tower surface, the external crane moves closer to the tower, thereby pushing the wheel more into the surface of the tower. This causes the lifting wire 402 of the external crane to make an angle to the vertical. In this embodiment, the angle is roughly 2 degrees. Due to this push towards the tower, movements of the external crane relative to the tower in a horizontal plane will not be transferred to the counterweight tool.

[0177] When the hook is properly engaged with the hoist block 300 and the wheel is in good contact with the tower surface, the external crane 400 is operated to lift the hook 510 along with the hoist block 300 upwardly.

[0178] As the external crane is operated to lift the hook 510 upwardly after engagement with the hoist block 300, the elongated portion 502 pivots from the tilted position to a substantially horizontal position, as shown in FIG. 22, due to the weight of the hoist block 300. It may be noted that the tower connection element 310 of the hoist block 300 disengages from the hoist block connection element 210 of the flange 202 as the counterweight tool 500 is further moved upwardly by the external crane 400. In this manner, the hoist block 300 is disengaged from the tower 200, and the load of the hoist block 300 is handled completely by the external crane 400. Again due to the form of the bumper structure of the hoist block, the hoist block moves upwardly with the bumper structure sliding along the surface of the tower.

[0179] Thereafter, the external crane 400 is operated to move the wheel 508 away from tower 200 in the horizontal direction without further lifting the counterweight tool 500 upwardly. It may be noted that the counterweight tool 500 during the entire process of removal of the hoist block 300 from the tower 200 is kept below the nacelle to prevent any interference of the external crane 400 or the counterweight tool 500 with the nacelle. Once the counterweight tool 500 has been moved in the horizontal direction such that the hoist block 300 is arranged at a horizontal distance from the tower 200, the counterweight tool 500 along with the hoist block 300 is lowered via the external crane 400. In this manner, the hoist block 300 can be lowered easily and without interfering with the nacelle.

[0180] A method for installation of the hoist block 300 to the top portion of the tower 200 when the nacelle is mounted to the tower 200 is now described (not shown). This is relevant when the TMC needs to be used during a maintenance operation. For example, if a gearbox or a blade needs to be replaced, then a hoist block can be attached to the upper flange and a TMC can be hoisted to the flange. The TMC can then do the maintenance work after which the TMC and the hoist block can be lowered again. However, due to the presence of the nacelle, it is not possible to mount the hoist block using the previously described procedure.

[0181] Hence, for mounting the hoist block 300 when the nacelle is in place, the counterweight tool is used. The lifting wire 402 of the external crane 400 is attached to the connection structure 520 of the counterweight tool 500. Thereafter, the external crane 400 is operated to vertically lift the counterweight tool. The hoist block 300 is then connected to the counterweight tool 500 by engaging the hook 510 of the counterweight tool 500 with the connection element of the hoist block 300. The hoist block 300 along with the counterweight tool 500 is then lifted to a vertical position at which the tower connection element 310 of the hoist block 300 is arranged above the flange 200 of the tower 200. It may be noted that as the hoist block 300 and the counterweight tool 500 is lifted, the elongated portion 502 is arranged substantially horizontal due to weight of the counterweight 514 at the second end 506 and the weight of the hoist block 300 at the first end 504 of the elongated portion 502. The hoist block 300 and the counterweight tool 500 are lifted with the hoist block 300 arranged proximate to the tower 200 and the counterweight 520 arranged distally from the tower 200 in the horizontal direction.

[0182] Upon lifting the hoist block 300 to the suitable vertical position, the user moves the external crane 400 to move the counterweight tool 500 and hence the hoist block 300 in the horizontal direction towards the tower 200 such that the bumper portion of the hoist block engages with the outer surface of the tower. The external crane continues to move the counterweight tool towards the tower until the wheel 508 of the counterweight tool 500 contacts the outer surface 208 of the tower 200. As the counterweight tool moves in, the hoist block moves against the tower until the tower connection element of the hoist block is arranged about the flange of the tower. As before, to reduce the effect of relative motion between the tower and the external crane, the external crane moves in further towards the tower, applying an angle to the lifting wire of the external crane. Subsequently, the external crane 400 is operated to lower the hoist block 300 keeping the wheel 508 in contact with the outer surface 208 of the tower 200. As the hoist block 300 is lowered, the tower connection element 310 of the hoist block 300 is engaged with the hoist block connection element 210 of the flange 202 of the tower 200. In this manner, the hoist block 300 is installed onto the tower 200. Subsequent to the engagement of the tower connection element 310 with the hoist block connection element 210, the operator operates the external crane 400 to move the wheel 508 away from the tower 200 and also lowers the counterweight tool. This causes the elongated portion 503 to tilt and move the counterweight 514 vertically downwards. When the elongated portion achieves a balance, the hook 510 of the counterweight tool can be disengaged from the hoist block 300. Upon disengagement of the hook 510 from the hoist block 300, the counterweight tool 500 is moved away from the tower 200 in the horizontal direction and is then lowered by operating the external crane 400. Figures 23 to 29 show some additional details of how the TMC 100 is connected to the tower 200. It should be noted that an alternative TMC is disclosed in applicant’s co-pending application PCT / EP2024 / 061324.

[0183] In the current embodiment, when the TMC 100 is being lifted, the arms 130, 132 of the TMC 100 are pivoted outwardly i.e. , away from each other so that there is room for the TMC 100 to be lifted along the tower 200. When the TMC 100 arrives at the crane connection flange 202 of the tower 200, see figure 23, the TMC 200 is positioned such that the arms 130, 132 are arranged on either side of the crane connection flange 202 of the tower.

[0184] As shown in FIGS. 23 to 29, each of the arms 130, 132 includes two portions, an inner arm portion 180 pivotally attached to the base portion 110 and an outer arm portion 182 pivotally attached to the inner arm portion 180. The inner arms portions 180 are configured to pivot towards each other and away from each other about vertical axes relative to the base portion 110 of the TMC 100. Similarly, the outer arm portions 182 are arranged to pivot towards and away from each other relative to the inner arm portions 180 about the vertical axes. Moreover, an inner clamp 134a of the clamps 134 is pivotally attached to the inner arm portion 180, while an outer clamp 134b of the clamps is pivotally attached to the outer arm portion 182.

[0185] The inner clamps 134a are arranged to pivot about a vertical axis 184, shown in FIG. 25, as well as a horizontal axis 186, shown in FIG. 24 relative to the inner arm portions 180. Similarly, the outer clamps 134b are arranged to pivot about a horizontal axis 188, shown in FIG. 24, and a vertical axis 189, shown in FIG. 25, relative to the outer arm portions 182. The pivoting of the clamps 134 relative to the associated arm portions 180, 182 facilitates in distributing the load of the TMC 100 on a larger area of the flange 202 when supported on the crane connection flange 202. It should be noted that the clamps 134 shown in the current invention are shown rather schematically and simplified. Depending on the size of the TMC and the weight of the load carried by the TMC, the clamps can be provided with additional weight distribution mechanisms, as described in applicant’s co-pending application PCT / EP2024 / 061324.

[0186] Further, to facilitate the engagement of the inner clamps 134a with the crane connection flange 200, each inner clamp 134a includes a downwardly extending protrusion 190, shown in FIGS. 24 and 27, adapted to be inserted inside the groove 212 of the crane connection flange 202. Also, each of the outer clamps 134b includes an upwardly facing surface 192, shown in FIG. 24, adapted to be arranged underneath the crane connection flange 202 and abutting a downward facing surface 250 of the crane connection flange 202.

[0187] For connecting the TMC 100 to the crane connection flange 202, upon positioning the arms 130, 132 on either side of the crane connection flange 202, the TMC 100 is tilted slightly so that the upwardly facing surfaces 192 of the outer clamps 134b are arranged underneath a horizontal plane including a downwardly facing surface of the flange 202 and the protrusions 190 of the inner clamps 134a are arranged above a horizontal plan including a upwards facing surface of the flange 202. However, the arms are still arranged awayf from the tower. This is shown in Figures 23 to 25 where one of the arms 130, 132 and the tower 200 have been removed so that the orientation of the TMC 100 can be seen relative to the crane connection flange 202 (shown schematically in dashed lines) of the tower 200. The TMC 100 is tilted by operating the hydraulic cylinders 128, 144 of the boom 112. By extending or retracting the boom cylinders, the base portion 110 of the TMC is tilted as desired.

[0188] When the arms 130, 132 and the base portion 110 are arranged in the correct position, the inner arm portions 180 are pivoted inwardly so that the downwardly extending protrusions 190 of the inner clamps 134a are arranged above the groove 212 of the crane connection flange 202. The TMC 100 is then lowered until the downwardly extending protrusions 190 are inserted into the groove 212 of the crane connection flange 200, as shown in Figures 26 and 27. Once the TMC 100 has been lowered so that a significant portion of the TMC’s weight is supported by the crane connection flange 200, the outer arm portions 182 of the arms 130, 132 are pivoted inwardly so that the upwardly facing surface 192 of the outer clamps 134b are arranged below the crane connection flange 202.

[0189] The base portion 110 of the TMC 100 is then again tilted, this time by retracting the boom cylinder and / or by further lowering the TMC 100 relative to the tower 200 to transfer more weight to the crane connection flange 202. This causes the outer clamps 134b to pivot upwardly relative of the outer arm portions 134b until the upwardly facing surfaces 192 of the outer clamps 182 engage with the downwards facing surface 250 of the crane connection flange 202, shown in Figures 28 and 29. In this way, the TMC 100 is engaged and supported on the crane connection flange 202 by a downwards force on a portion of the crane connection flange 202 located proximal to the TMC and an upward force on a portion of the crane connection flange 202 located distally to the TMC. In this position the TMC is completely supported by the crane connection flange 202 of the tower 200.

[0190] Furthermore, in this embodiment of the TMC 100, the clamps 134 comprise oppositely engaging surfaces to more securely engage with the crane connection flange 202. The inner clamps 134a have lower clamping engaging surfaces which displace upwardly to engage the downward facing surface 250 of the crane connection flange 202. Similarly, the outer clamps 134b have downwardly displacing engaging surfaces which displace downwardly to engage an upward facing surface of the crane connection flange 202. In most cases, the forces exerted by the oppositely engaging surfaces will be much lower than forces exerted by the “main” engaging surfaces. However, depending on the position of the boom 112 and the weight of the load carried by the boom 112, in certain cases, the loads can change. Oppositely engaging surfaces are disclosed in applicant’s copending application PCT / EP2024 / 061324.

[0191] In general, it should be noted that the figures have shown the example embodiments in a simplified manner so that the main invention concepts disclosed in the current specification could be illustrated. For example, the details of the wire routing systems, the number of loops of wire, the details of the wires, the details of the boom adjusting mechanism, the clamping mechanisms, etc have been simplified to make the current specification and figures easier to read and understand. However, we maintain that the person skilled in the art of cranes will be able to supply the missing details based on his or her technical knowledge.

Claims

Claims1 . A method for mounting a tower mountable crane (TMC) to a tower of an wind turbine, for example an offshore wind turbine, said tower having a central axis extending along a length of the tower in a vertical direction, said TMC comprising a base portion which is arranged to be connectable to a tower of a wind turbine, a boom having a base end pivotally connected to the base portion and a tip end arranged distally from the base end and a lifting hook connected to a tip end of the boom via a cable controlled by a winch, the method comprising: a. lifting a hoist block and mounting the hoist block to an upper portion of the tower, b. connecting the cable between the TMC and the hoist block such that the cable extends from the TMC to the hoist block and back to the TMC, c. lifting the TMC using a lifting wire of an external crane, d. tensioning the cable extending between the hoist block and the TMC to partially support the TMC via said cable; e. increasing the tension in the cable until the TMC is completely supported by said cable; and f. disconnecting the lifting wire of the external crane from the TMC.

2. The method of claim 1 , characterized in that the horizontal distance between the TMC and the tower is controllable by increasing or decreasing the tension on the cable and / or decreasing or increasing respectively a tension of the lifting wire of the external crane.

3. The method of any one of claims 1 to 2, characterized in that the method includes engaging a sliding element connected to the TMCwith an outer surface of the tower before disconnecting the lifting wire of the external crane from the TMC.

4. The method of any one of claims 1 to 3, characterized in that the method includes engaging a bumper of the TMC with an outer surface of the tower when the TMC is partly supported by the cable and partly supported by the lifting wire of the external crane.

5. The method of claim 4, characterized in that the bumper is arranged to allow the base portion of the TMC to displace relative to the tower in a direction which is parallel to the central axis of the tower.

6. The method of claim 4 or 5, characterized in that the bumper is movably connected to the base portion of the TMC and arranged to be extended and retracted relative to the base portion in a direction having a vector component which is perpendicular to the central axis of the tower to control the contact of the bumper with the surface of the tower.

7. The method of claim 6, characterized in that after the bumper is engaged with the outer surface of the tower, the bumper is extended further from the base portion of the TMC to push the TMC away from the outer surface of the tower.

8. The method of any one of the preceding claims, characterized in that the TMC is lifted from the deck with the boom of the TMC arranged in a horizontal position.

9. A tower mountable crane (TMC) adapted to be mounted to a tower of a wind turbine, said tower having a central axis extending along a length of the tower in a vertical direction, the TMC comprisinga. a base portion; and b. a boom having a base end pivotally connected to the base portion and a tip end arranged distally from the base portion and a lifting hook connected to a tip end of the boom via a cable, characterized in that c. the TMC further comprises a bumper movably connected to the base portion and arranged to be displaced between an extended position and a retracted position in a radial direction relative to a central axis of the tower to control a contact of the bumper with the tower and / or a position of the bumper relative to the tower and / or a position of the base portion of the TMC relative to the tower.

10. The TMC according to claim 9, characterized in that the TMC includes an actuator connected between the base portion of the TMC and the bumper and configured to displace the bumper between the extended position and the retracted position.11 .The TMC according to claim 9 or 10, characterized in that the bumper is arranged to be able to slide along the tower when the bumper is in contact with the tower.

12. The TMC according to any one of claims 9-11 characterized in that the bumper includes at least one wheel or roller adapted to contact the tower and slide along the tower.

13. The TMC according to any one of claims 9-12, characterized in that the bumper is arranged to prevent motion of the TMC perpendicular toa plane comprising the central axis of the tower and passing through a centre of the base portion of the TMC.

14. A tower mountable crane (TMC) adapted to be mounted to a tower of wind turbine, for example an offshore wind turbine, said tower having a central axis extending along a length of the tower in a vertical direction, the TMC comprising: a. a base portion, b. a boom having a base end pivotally connected to the base and a tip end arranged distally from the base, c. and a lifting hook connected to a tip end of the boom via a cable characterized in that d. the TMC includes a bumper connected to the base and arranged to contact an outer surface of the tower and in that the bumper is arranged such that the base portion of the TMC can move relative to the tower along a direction which is parallel to the central axis of the tower, when the bumper is in contact with the tower.

15. A tower mountable crane (TMC) adapted to be mounted to a tower of a wind turbine, for example an offshore wind turbine, said tower having a central axis extending along a length of the tower in a vertical direction, the TMC comprising: a. a base portion; b. a boom having a base end pivotally connected to the base and a tip end arranged distally from the base, and c. a lifting hook connected to a tip end of the boom via a cable d. and where the boom is arranged to pivot about a horizontal axis between a vertically upward position and a vertically downward position, wherein in the vertically upward position, the tip end isarranged upwardly of the base portion, while in the vertically downward position, the tip end is arranged downwardly of the base portion, characterized in that e. the TMC includes a sliding element connected to the boom, wherein the sliding element is arranged to contact and slide along an outer surface of the tower when the boom is arranged in the vertically downward position and the TMC is being lifted along the tower.

16. The TMC according to claim 15, characterized in that the sliding element is at least one wheel or roller.

17. The TMC according to claim 15 or 16, characterized in that the sliding element comprises at least two wheels, at least one wheel arranged on either side of a plane comprising the central axis of the tower when the sliding element is in contact with the tower.

18. The TMC according to any one of the claims 15 to 17, characterized in that the sliding element is arranged on the side of the boom which is opposite to the lifting hook in the position which the boom would be in when connected to the tower and in the vertically upwards position.

19. The TMC according to any one of the claims 15 to 18, characterized in that the sliding element is arranged between the base end and the tip end of the boom.

20. The TMC according to claim 19, characterized in that the sliding element is arranged closer to the tip end than the base end.

21. The TMC according to any one of claims 15 to 20, characterized in that the sliding element is arranged at an offset to a line joining the tip end and the base end of the boom.

22. The TMC according to claim 21 , characterized in that the offset is greater than 5% of the length of said line.

23. The TMC according to any one of the claims 15 to 22, characterized in that the sliding element is arranged to prevent motion of the boom perpendicular to a plane comprising the central axis of the tower and a centre of the base portion of the TMC.

24. A hoist block for use in a method for lifting a tower mountable crane (TMC) to a tower of a wind turbine, for example an offshore wind turbine, the hoist block comprising: a. a frame, b. a connection element which is connectable to a lifting wire of a crane, and c. at least one tower connection element coupled to the frame and configured to attach the hoist block to the tower, characterized in that d. the hoist block includes a bumper structure connected to the frame, said bumper structure comprising a tower contact surface having at least an upper and a lower portion spaced apart from each other in the vertical direction, said at least upper and lower portions being arranged to contact an outer surface of the tower when the hoist block is being mounted to the tower and when the hoist block is mounted to the tower.

25. The hoist block according to claim 24, characterized in that the bumper structure is arranged below the at least one tower connection element.

26. The hoist block according to claim 24 or 25, characterized in that the tower contact surface includes a main contact portion which is arranged to contact an area of the surface of the tower, said main contact portion having a main contact surface with a main contact vector A which is arranged perpendicular to the main contact surface, said bumper structure further comprises a first side contact portion and a second side contact portion, said first side contact portion is arranged to contact another area of the surface of the tower, said first side contact portion being located offset from the main contact surface in a direction both along the main contact vector and to the side of the main contact vector and said second side contact portion being arranged to contact another area of the surface of the tower located offset from the main contact surface in a direction both along the main contact vector ahead and to the opposite side of the main contact portion.

27. Hoist block according to any one of the claims 24 to 26 characterized in that a Centre of Gravity (COG) of the hoist block is arranged such that when the hoist block is hanging from a lifting wire of a crane, the tower contact surface of the bumper structure is arranged such that the lower contact portion will contact the tower surface before or at the same time as the upper contact portion.

28. Hoist block according to claim 27, characterized in that the COG of the hoist block is further arranged such that when the upper and lower contact portions of the tower contact surface are engaged with the tower surface, the Centre of Gravity of the hoist block will exert amoment about the upper contact portion which pushes the lower contact portion towards the tower surface.

29. Hoist block according to claim 28, characterized in that the moment exerted about the upper contact portion is arranged such that the angle of a lifting wire of a crane lifting the hoist block at the position where the upper and lower contact surfaces first contact the surface of the tower can be increased by at least 2 degrees in a direction towards the centre of the tower without the bottom contact surface leaving the surface of the tower.

30. A method for removing a hoist block from a tower of a wind turbine having a nacelle mounted on the tower, the method comprising: a. lifting a counterweight tool using an external crane, wherein the counterweight tool includes an elongated portion having a first end and second end, a sliding element attached to the first end of the elongated portion, a connector, for example a hook, connected to a wire attached near the first end of the elongated portion, and a counterweight attached to the second end of the elongated portion, and a connection structure arranged between the first end and the second end, wherein the external crane is connected to the connection structure; b. positioning the connector of the counterweight tool upwardly of the hoist block; c. engaging the connector with the hoist block; d. moving the counterweight tool towards the tower such that the sliding element contacts an outer surface of the tower and e. disengaging the hoist block from the tower by lifting the counterweight tool using the external crane while keeping the sliding element in contact with the tower.

31. The method according to claim 30, characterized in that the method further includes a. moving the hoist block away from the tower by operating the external crane upon disengagement of the hoist block from the tower, and b. lowering the hoist block by lowering the counterweight tool using the external crane upon moving the hoist block away from the tower.

32. The method according to claim 30 or 31 , characterized in that the counterweight tool is arranged such that when the sliding element is in contact with the tower and the connector is connected to the hoist block, the wire connecting the connector to the elongated portion is arranged at an angle to the vertical.

33. The method according to any one of claims 30 to 32, characterized in that the sliding element is a wheel.

34. The method according to any one of claims 30 to 33, characterized in that the sliding element comprises a shock absorbing element to reduce the force of contact between the sliding element and the tower.

35. The method according to any one of claims 30 to 34, characterized in that the sliding element is arranged to prevent motion of the sliding element relative to the tower in the horizontal plane when the sliding element is in contact with the tower.

36. Tower mountable crane (TMC) comprising a base portion, a first inward tower engaging element, a second inward tower engaging element, a first outer tower engaging element and a second outer tower engaging element, the first and second inward tower engagingelements comprising downwardly extending elements which are arranged to be inserted into an upwardly facing groove of a proximal crane connection element extending from an outer surface of the tower and the first and second outer tower engaging elements comprising upwardly facing engaging elements which engage with a downwardly facing surface of a distal crane connection element of the tower.37.TMC according to claim 36, characterized in that the first and second outer tower engaging elements are arranged further away from the base portion of the TMC than the first and second inner tower engaging elements.

38. TMC according to claim 36 or 37, characterized in that the TMC comprises a first arm extending outwardly from the base portion and a second arm extending outwardly from the base portion, the first inner tower engaging element being connected to the first arm and the second inner tower engaging element being connected to the second arm.

39. TMC according to claim 38, characterized in that the first arm is pivotably connected to the base portion about a first vertical axis and the second arm is pivotably connected to the base portion about a second vertical axis.

40. TMC according to claim 38 or 39, characterized in that the TMC comprises a third arm and a fourth arm, said first outer tower engaging element being connected to the third arm and the second outer tower engaging element being connected to the fourth arm.7041. TMC according to claim 40, characterized in that the third arm is connected to the first arm and the fourth arm is connected to the second arm.42.TMC according to claim 41 , characterized in that the third arm is pivotably connected to the first arm about a third vertical axis and the fourth arm is pivotably connected to the second arm about a fourth vertical axis.43.TMC according to any one of the claims 36 to 42, characterized in that the TMC is arranged to be pivotable about a horizontal axis relative to the tower when supported by the cable of the TMC, such that TMC can be arranged in a first position where the first and second inner engaging elements are arranged above the proximal crane connection element of the tower and the first and second outer engaging elements are arranged below the distal crane connection element of the tower and in a second position where the first and second inner engaging elements are engaging an upper surface of the proximal crane connection element of the tower and where the first and second outer engaging elements are engaging a lower surface of the distal crane connection element.

Images