Lifting device and method for lifting longitudinally bendable structure such as wind turbine blade

Abstract

A lifting device (10) for lifting a longitudinally bendable structure, such as a wind turbine blade, said lifting device (10) comprising-a longitudinal beam (12) comprising one or more segments and one or more rigging elements (14); -a plurality of attachment units (20) positioned along the longitudinal beams; the attachment unit (20) comprises: a vacuum gripper (22) for gripping a portion of the longitudinally bendable structure; -a displaceable arm (24) connected to the vacuum gripper (22), said displaceable arm (24) being linearly displaced between a retracted position and an extended position; -a power transmission unit (26) configured for displacing the displaceable arm (24) between a retracted position and an extended position; -a global power transmission system in fluid communication with the power transmission unit (26), the global power transmission system configured for balancing the power transmission unit (26).

Description

Technical Field

[0001] The present invention relates to a lifting device and method for lifting longitudinally bendable structures such as wind turbine blades. Background Art

[0002] As part of the green transition, wind turbines have been rapidly installed globally, and during the production and installation of wind turbines, it is necessary to lift wind turbine blades. However, wind turbine blades are flexible, and the flexibility increases gradually from the root to the tip of the blade. This flexibility significantly complicates the lifting process and also significantly complicates the requirements for lifting devices.

[0003] Current lifting methods and devices are typically configured to grip the wind turbine blade at two positions, either at the two ends of the wind turbine blade or in the middle of the wind turbine blade. The problem with these lifting methods and devices is that they cannot adapt to the bending that occurs at the tip of the wind turbine blade during the lifting process. This can lead to excessive bending and flexing of the wind turbine blade, which may cause damage to the wind turbine blade and even, in the worst case, cause the blade to fall.

[0004] Other existing methods and devices use multiple suction cups to attach the wind turbine blade to the lifting device. The problem with these methods and devices is that they cannot adapt to the bending that occurs at the tip of the wind turbine blade during the lifting process. Thus, when the wind turbine blade bends or flexes, the blade may detach itself from one or more suction cups, resulting in the wind turbine blade falling. Another drawback is that, to avoid the wind turbine blade falling, an oversized lifting device is required to cope with the loss of adhesion that occurs when the suction cups lose their gripping force.

[0005] The prior art requires a lifting device and method for lifting wind turbine blades that can adapt to the bending of the wind turbine blade tip without losing the grip on the wind turbine blade, thereby ensuring controllability during the lifting process and minimizing the risk of damage and falling of the wind turbine blade.

[0006] Object of the Invention

[0007] The object of the present invention is to provide a device and method for lifting longitudinally bendable structures such as wind turbine blades, which can adapt to the bending and flexing of the longitudinally bendable structure without losing the grip on the longitudinally bendable structure, thereby ensuring controllability of the entire lifting process. Summary of the Invention

[0008] The object of the present invention is achieved by a lifting device for lifting a longitudinally bendable structure, such as a wind turbine blade. The lifting device comprises:

[0009] - A longitudinal beam, which includes one or more segments and one or more rigging elements;

[0010] - A plurality of attachment units positioned along the longitudinal beam; the attachment unit includes:

[0011] - A vacuum gripper for gripping a part of a longitudinally bendable structure;

[0012] - A displaceable arm connected to the vacuum gripper, which can be linearly displaced between a retracted position and an extended position;

[0013] - A power transmission unit configured to displace the displaceable arm between the retracted position and the extended position;

[0014] - A global power transmission system in fluid communication with the power transmission unit, which is configured to balance the power transmission unit.

[0015] The lifting device is a lifting device for lifting a longitudinally bendable structure, such as a wind turbine blade, where a part or the whole wind turbine blade can be lifted. Compared with the more flexible tip of the wind turbine blade, the more rigid root end of the wind turbine blade is easier to grip. Therefore, the prior art can lift the root end of the wind turbine blade rather than the tip. The present invention can lift the whole blade, but is usually used in combination with the prior art, where the prior art lifts the root end and the present invention lifts the tip of the wind turbine blade.

[0016] In some embodiments, the lifting device can be lifted by a crane or other means well-known to those skilled in the art.

[0017] The longitudinally bendable structure can be any long and heavy bendable object, such as an aircraft wing or a roof, or a curved object, such as a wind turbine blade. Therefore, it is necessary to provide a lifting device that can adapt to, for example, a curved bendable structure.

[0018] The longitudinal beam can be positioned substantially parallel to and above the longitudinally bendable structure to be lifted by the lifting device, thereby achieving balanced and stable lifting of the longitudinally bendable structure.

[0019] In some embodiments, the longitudinal beam can include four segments and one or more rigging elements.

[0020] The plurality of attachment units can be evenly distributed along the longitudinal beam, thereby obtaining vacuum grippers evenly distributed along the longitudinal beam. The advantage of this is to ensure uniform gripping force along the entire longitudinally bendable structure.

[0021] In some embodiments, the end segments of the longitudinal beam can include more attachment units than the middle segments.

[0022] In some embodiments, the middle section of the longitudinal beam may include more attachment units than the end sections.

[0023] In some embodiments, all sections of the longitudinal beam may include the same number of attachment units.

[0024] The vacuum gripper may be a suction plate or a suction cup configured to grip a portion of the longitudinally bendable structure.

[0025] A displaceable arm substantially orthogonal to the longitudinal beam (along the direction of the longitudinally bendable structure) linearly displaces between a retracted position and an extended position. Since the displaceable arm is connected to the vacuum gripper, the displacement of the displaceable arm causes the vacuum gripper to displace between the retracted position and the extended position.

[0026] The displacement of the vacuum gripper may be a displacement to any position between the retracted position and the extended position.

[0027] In the retracted position, the displaceable arm may cause the vacuum gripper to retract towards the longitudinal beam and away from the longitudinally bendable structure.

[0028] In the extended position, the displaceable arm may cause the vacuum gripper to extend towards the longitudinally bendable structure and away from the longitudinal beam.

[0029] The advantage of this is that the position of each vacuum gripper can be adjusted to fit the shape of the longitudinally bendable structure, such as a curved wind turbine blade, thereby supporting its original shape when lifting the longitudinally bendable structure.

[0030] A vacuum can be formed at the vacuum gripper by one or more vacuum pumps connected to the vacuum gripper to provide suction. Each vacuum gripper may have one vacuum pump, or two or more vacuum grippers may have a common vacuum pump. In Figure 5 the illustrated embodiment, one vacuum pump is used to provide suction for all the vacuum grippers shown in Figure 5 the figure.

[0031] The displaceable arm is displaced between the retracted position and the extended position by a power transmission unit. The power transmission unit may be pneumatic or hydraulic. When hydraulic fluid or pneumatic fluid flows into the power transmission unit, the displaceable arm may be displaced towards the extended position, and when the hydraulic fluid or pneumatic fluid flows out of the power transmission unit, the displaceable arm may be displaced towards the retracted position. Thereby, a single vacuum gripper is adjusted to different displacement positions to fit the shape of the longitudinally bendable structure along the longitudinal beam.

[0032] A plurality of power transmission units included in the plurality of attachment units are in fluid communication with a global power transmission system, where the fluid can be an inert gas, air, water, or oil. During the clamping process, the global power transmission system can allow the position of the power transmission unit to the longitudinally bendable structure to be adjusted individually without affecting other power transmission units. This ensures a strong clamping and optimal contact between the vacuum gripper and the longitudinally bendable structure.

[0033] The global power transmission system can include a fluid pump for controlling the flow rate in the global power transmission system. The fluid pump can be configured to increase or decrease the flow rate in the global power transmission system.

[0034] During the lifting process, the global power transmission system can form an internal interdependence between the power transmission units. When the longitudinally bendable structure bends during the lifting process, it causes the displaceable arm connected to the vacuum gripper at the bending point to displace in the direction of the bend. This displacement can displace the displaceable arm through a change in the fluid volume of the power transmission unit. To counteract the bending movement on the longitudinally bendable structure to prevent the vacuum gripper from losing its clamping force, the remaining displaceable arms can be displaced in the direction to counteract the displacement caused by the bend and to the extent to counteract the displacement caused by the bend. Thus, the global power transmission system balances the power transmission units, enabling the vacuum gripper to follow the bending movement of the longitudinally bendable structure and preventing the loss of clamping force resulting in the longitudinally bendable structure from falling.

[0035] On one aspect of the lifting device, the power transmission unit can be pneumatic or hydraulic.

[0036] In some embodiments, the power transmission unit can be pneumatic, where the fluid can be an inert gas or air.

[0037] In some embodiments, the power transmission unit can be hydraulic, where the fluid can be a suitable hydraulic oil.

[0038] On one aspect of the lifting device, the global power transmission system and the power transmission unit can share a common fluid tank.

[0039] The common fluid tank can be in fluid communication with the global power transmission system and the power transmission unit, where the fluid volume can be adjustable or fixed. The adjustable fluid volume allows for individual and independent displacement of the power transmission unit, while the fixed fluid volume provides an interdependence between the power transmission units, where the displacement of one power transmission unit is balanced by the other power transmission units.

[0040] The fluid flowing in and out of the common fluid tank can be controlled by a valve included in the global power transmission system. The valve is displaced between an open state and a closed state, in which in the open state the fluid flows in and out of the common fluid tank, and in the closed state the fluid flow from the common fluid tank is blocked. The valve can be placed between the fluid pump and the common fluid tank or after the fluid pump, and the effect will be the same. In some embodiments, when the valve is positioned downstream of the fluid pump, due to the possible presence of forward flow and backflow, the valve will be two valves.

[0041] Thus, when the valve is in the open state, the fluid volume is adjustable, while when the valve is in the closed state, the fluid volume is fixed.

[0042] The entire fluid system consisting of the common fluid tank, the global power transmission system, and the power transmission unit includes a constant and fixed total fluid volume. The fixed total fluid volume is divided into a first fluid volume and a second fluid volume. The first fluid volume is located between the common fluid tank and the valve, and the second fluid volume is located between the valve and the power transmission unit positioned downstream. Thus, when the valve is open, the fluid flows freely between the first fluid volume and the second fluid volume, which results in the first fluid volume and the second fluid volume being adjustable; while when the valve is closed, the fluid flow between the first fluid volume and the second fluid volume is blocked, which results in the first fluid volume and the second fluid volume being fixed.

[0043] In some embodiments, the fluid connecting each power transmission unit can be controlled by a local fluid pump configured to control the fluid flowing in and out of the power transmission unit. Thus, the displacement of the displaceable arm can be controlled.

[0044] In one aspect of the lifting device, the global power transmission system can change between two states:

[0045] - A connected state, in which the fluid volume in the common fluid tank is adjustable, thereby enabling the power transmission unit to be controlled individually; and

[0046] - A lifting state, in which the fluid volume in the common fluid tank is fixed, thereby enabling the power transmission unit to achieve self - balance by contracting and / or extending the displaceable arm.

[0047] In the connected state, the fluid volume is adjustable, which allows adjusting the position of an individual vacuum gripper relative to the longitudinally bendable structure because fluid can flow into and out of a common fluid tank. The position of the vacuum gripper is controlled by fluid flowing into the power transmission unit to extend the displaceable arm towards the longitudinally bendable structure, or by fluid flowing out of the power transmission unit to retract the displaceable arm away from the longitudinally bendable structure. Since the fluid volume is adjustable, the volume of fluid flowing into and out of each individual power transmission unit is independent of that in other power transmission units.

[0048] Thus, each individual vacuum gripper can be adjusted to a different displacement position without affecting the positions of other vacuum grippers to accommodate the shape of the longitudinally bendable structure that is generally parallel to and below the longitudinal beam.

[0049] The advantage of this is to achieve a strong grip and optimal contact between the vacuum gripper and the longitudinally bendable structure.

[0050] In the lifting state, the fluid volume is fixed, which creates an internal interdependence between the power transmission units. Because all power transmission units are in fluid communication with each other through a global power transmission system, a fixed common fluid tank causes a change in the fluid volume in one power transmission unit to result in a reverse compensatory change in the fluid volume of other power transmission units. Therefore, when the longitudinally bendable structure bends during lifting, the vacuum gripper located at the bend undergoes displacement in the bending direction. That is, if the longitudinally bendable structure bends away from the longitudinal beam, the displaceable arm connected to the vacuum gripper located at the bend can extend; if the longitudinally bendable structure bends towards the longitudinal beam, the displaceable arm connected to the vacuum gripper located at the bend can retract. To accommodate the change in the fluid volume of the power transmission unit located at the bend, the other transmission units will displace in the direction and to the extent that offsets the displacement caused by the bending.

[0051] The global power transmission system automatically adjusts the displacement of the fluid in the power transmission unit according to the degree of bending of the longitudinally bendable structure. Thus, the global power transmission system can balance the power transmission units automatically, enabling the displaceable arms to follow the bending movement of the longitudinally bendable structure.

[0052] The advantage of this is to prevent one or more vacuum grippers from losing their gripping force due to the bending movement of the longitudinally bendable structure. This is a very significant advantage because losing the gripping force may cause the longitudinally bendable structure to fall.

[0053] The advantage of the self - balancing of the power transmission units is that there is no need to control individual power transmission units during lifting.

[0054] On one aspect of the lifting device, the global power transmission system may include a valve downstream of the common fluid tank and upstream of the power transmission unit. The valve is open in the connected state and closed in the lifted state.

[0055] The state of the global power transmission system can be controlled by the displacement of the valve included in the global power transmission system, as the valve controls the inflow and outflow of fluid from the common fluid tank. In the connected state, when the valve is open, fluid can flow in and out of the common fluid tank, while in the lifted state, when the valve is closed, the inflow and outflow of fluid from the common fluid tank are blocked, and the total fluid volume of the power transmission unit is constant.

[0056] Thus, when the valve is in the connected state, the fluid volume is adjustable, while when the valve is in the lifted state, the fluid volume is fixed.

[0057] On one aspect of the lifting device, one or more vacuum grippers can be attached to one or more displaceable arms in a tiltable manner.

[0058] This allows adjustment of the vacuum gripper to adapt to the surface curvature of the longitudinally bendable structure, and thus achieves an optimal contact between the vacuum gripper and the longitudinally bendable structure, resulting in a strong clamping force.

[0059] On one aspect of the lifting device, the attachment unit may include a local vacuum tank.

[0060] The local vacuum tank creates a negative pressure between the vacuum gripper and the surface of the longitudinally bendable structure, thereby adsorbing the vacuum gripper to the surface of the longitudinally bendable structure. The local vacuum tank also ensures that suction can be provided even in the event of power loss, so that the one or more vacuum pumps can no longer provide suction and the clamping force will not be immediately lost. In addition, it is not necessary for the one or more vacuum pumps to operate continuously, as the local vacuum tank will act as a buffer.

[0061] In some embodiments, each attachment unit may include a vacuum pump, thereby creating an effective vacuum at each vacuum gripper.

[0062] In some embodiments, a common vacuum pump can be connected to one or more common vacuum tanks, and the volume of the common vacuum tank is 5 times, or 10 times, or 25 times larger than that of a single local vacuum tank. The one or more common vacuum tanks are in fluid communication with the local vacuum tanks. Subsequently, the one or more vacuum pumps pump the one or more common vacuum tanks to create a vacuum in the one or more common vacuum tanks, which then provides the suction force of the one or more local vacuum tanks, and in turn provides the suction force for the vacuum grippers. This ensures a negative pressure between the vacuum gripper and the surface of the longitudinally bendable structure, which forms a strong and continuous adsorption during the lifting process.

[0063] In some embodiments, the lifting device may include two common vacuum tanks.

[0064] The advantage of providing a common vacuum pump is energy conservation and the formation of a uniform and constant vacuum between the vacuum gripper and the surface of the longitudinally bendable structure.

[0065] The advantage of the local and common vacuum tanks is that if the vacuum pump loses power, the vacuum stored in the vacuum tanks maintains the negative pressure between the vacuum gripper and the surface of the longitudinally bendable structure. This prevents the longitudinally bendable structure from falling during a short power shortage.

[0066] In one aspect of the lifting device, the longitudinal beam may include a beam having a length in the range of 5 m to 150 m, or 10 m to 125 m, or 25 to 100 m, such as a 40 m or 60 m beam.

[0067] In some embodiments, the length of the longitudinal beam may be approximately equal to or longer than the length of the longitudinally bendable structure.

[0068] The object of the present invention is achieved by a method for lifting a longitudinally bendable structure, such as a wind turbine blade. The method includes the steps of:

[0069] - providing a lifting device according to one or more of claims 1 to 7;

[0070] - positioning the lifting device along the longitudinally bendable structure;

[0071] - displacing the displaceable arm using a power transmission unit such that the vacuum gripper engages with the surface of the longitudinally bendable structure;

[0072] - lifting the longitudinally bendable structure while using a global power transmission system to balance the power transmission unit.

[0073] The longitudinally bendable structure can be any long and heavy bendable object, such as an aircraft wing or a roof, and it can be a curved object, such as a wind turbine blade. Thus, it is necessary to provide a method for lifting a longitudinally bendable structure that can adapt to, for example, a curved longitudinally bendable structure.

[0074] The step of providing may be the step of providing a lifting device for lifting a longitudinally bendable structure, such as a wind turbine blade, where a part of the wind turbine blade or the entire wind turbine blade can be lifted.

[0075] The step of positioning may be the step of positioning the longitudinal beam of the lifting device substantially parallel to and substantially above the longitudinally bendable structure to be lifted by this method, thereby achieving a balanced and stable lift of the longitudinally bendable structure.

[0076] The step of displacement can be a step of linearly displacing a displaceable arm that is substantially orthogonal to the longitudinal beam (in the direction of the longitudinally bendable structure) between a retracted position and an extended position. The displacement of the displaceable arm connected to the vacuum gripper causes the vacuum gripper to displace between a retracted position and an extended position. The vacuum gripper can be displaced to any position between the retracted position and the extended position.

[0077] The advantage of this is that the position of each vacuum gripper can be adjusted to fit the shape of the longitudinally bendable structure, such as a curved wind turbine blade, thereby supporting its original shape when lifting the longitudinally bendable structure.

[0078] The power transmission unit displaces the displaceable arm between a retracted position and an extended position. The power transmission unit can be pneumatic or hydraulic. When hydraulic fluid or pneumatic fluid flows into the power transmission unit, the power transmission unit displaces the displaceable arm towards the extended position. When hydraulic fluid or pneumatic fluid flows out of the power transmission unit, the power transmission unit displaces the displaceable arm towards the retracted position. Thus, a single vacuum gripper is adjusted to different displacement positions to engage with the surface of the longitudinally bendable structure.

[0079] The step of displacement can also be a step of displacing the individual displaceable arms connected to the vacuum gripper independently of each other.

[0080] The advantage of this is that each vacuum gripper can be adjusted to fit the shape of the longitudinally bendable structure along the longitudinal beam, achieving an optimal contact between the vacuum gripper and the longitudinally bendable structure, which results in a strong clamping force.

[0081] The power transmission unit is in fluid communication with the global power transmission system. During the step of lifting, the global power transmission system can form an internal interdependence between the power transmission units. When the longitudinally bendable structure bends during lifting, it causes the displaceable arms connected to the vacuum grippers located at the bend to displace along the bending direction. This displacement can displace the displaceable arm through a change in the fluid volume of the power transmission unit. To counteract the bending movement on the longitudinally bendable structure to prevent the vacuum grippers from losing the clamping force, the remaining displaceable arms can be displaced in the direction and to the extent that offsets the displacement caused by the bending. Thus, the global power transmission system balances the power transmission units, enabling the vacuum grippers to follow the bending movement of the longitudinally bendable structure and preventing the loss of the clamping force that would cause the longitudinally bendable structure to drop.

[0082] In one aspect of the method, the step of displacement can be performed when the global power transmission system is in a connected state, while the step of lifting is performed when the global power transmission system is in a lifting state.

[0083] During the displacement step, the global power transmission system can be in a connected state where the fluid volume is adjustable. The adjustable fluid volume allows the fluid volume flowing in and out of each individual power transmission unit to be independent of the fluid volume flowing in and out of other power transmission units. Thus, each individual vacuum gripper can be adjusted to different displacement positions between the retracted position and the extended position without affecting the positions of other vacuum grippers. This adapts the position of the vacuum grippers to the shape of the longitudinally bendable structure that is generally parallel to and below the longitudinal beam.

[0084] Such an advantage is that it achieves a strong grip and optimal contact between the vacuum grippers and the longitudinally bendable structure.

[0085] During the lifting step, the global power transmission system can be in a lifting state where the fluid volume is fixed. The fixed fluid volume can create an internal interdependence between the power transmission units because all the power transmission units are fluidly connected to each other through the global power transmission system. A change in the fluid volume in one power transmission unit causes a reverse compensatory change in the fluid volume of other power transmission units. Therefore, when the longitudinally bendable structure bends during lifting, the vacuum grippers located at the bend displace in the direction of the bend, and to accommodate these changes in the fluid volume of the power transmission units, the other transmission units displace in the direction and to the extent that offsets the displacement caused by the bend.

[0086] Thus, during the lifting step, the global power transmission system automatically adjusts the displacement of the fluid within the power transmission units according to the degree of bending of the longitudinally bendable structure. Thus, the global power transmission system can balance the power transmission units, enabling the displaceable arm to follow the bending movement of the longitudinally bendable structure.

[0087] Such an advantage is that it prevents one or more vacuum grippers from losing their gripping force due to the bending movement of the longitudinally bendable structure during the lifting step. This is a very significant advantage because losing the gripping force may cause the longitudinally bendable structure to drop. Brief Description of the Drawings

[0088] Figure 1 The attachment unit is shown.

[0089] Figure 2 A front view and an enlarged view of the lifting device for lifting the longitudinally bendable structure are shown.

[0090] Figure 3 A top view and an enlarged view of the lifting device for lifting the longitudinally bendable structure are shown.

[0091] Figure 4Shows the fluid communication between a common fluid tank, a global power transmission system, and a power transmission unit.

[0092] Figure 5 Shows a side view of a lifting device for lifting a longitudinally bendable structure.

[0093] Figure 6 Shows a front perspective view of a lifting device for lifting a longitudinally bendable structure and two enlarged views.

[0094] Figure 7 Shows a method for lifting a longitudinally bendable structure.

[0095] Lifting device 10 Longitudinal beam 12 Sling element 14 Attachment unit 20 Vacuum gripper 22 Displaceable arm 24 Power transmission unit 26 Common fluid tank 30 Fluid pump 32 Valve 34 Local vacuum tank 40 Vacuum pump 42 Common vacuum tank 50 Connection state 130 Lifting state 140 Method 1000 Provide 1100 Position 1200 Displacement 1300 Lift 1400 Detailed Description

[0096] Figure 1 Shows an attachment unit 20, where a vacuum gripper 22 is configured to grip a portion of a longitudinally bendable structure. The vacuum gripper 22 is connected to a displaceable arm 24, which is substantially orthogonal to the longitudinal beam 12 (along the direction of the longitudinally bendable structure) Figures 2 - 5 ) The displaceable arm 24 of the ( ) linearly displaces between a retracted position and an extended position. Thereby, the displacement of the displaceable arm 24 causes the displacement of the vacuum gripper 22 between the retracted position and the extended position. The displacement of the vacuum gripper 22 can be to any position between the retracted position and the extended position.

[0097] In the retracted position, the displaceable arm 24 can retract the vacuum gripper 22 towards the longitudinal beam 12 and away from the longitudinally bendable structure.

[0098] In the extended position, the displaceable arm 24 can extend the vacuum gripper 22 towards the longitudinally bendable structure and away from the longitudinal beam 12.

[0099] Thereby, the position of the vacuum gripper 22 can be adjusted to adapt to the shape of the longitudinally bendable structure, such as a curved wind turbine blade.

[0100] The vacuum gripper 22 can also be attached to the displaceable arm 24 in a tiltable manner. This allows the adjustment of the vacuum gripper 22 to adapt to the surface curvature of the longitudinally bendable structure, thereby achieving an optimal engagement between the vacuum gripper 22 and the longitudinally bendable structure.

[0101] The vacuum gripper 22 can be a suction plate or a suction cup, which is configured to grip a portion of the longitudinally bendable structure.

[0102] The displaceable arm 24 is displaced between a retracted position and an extended position by a power transmission unit 26. The power transmission unit 26 can be pneumatic or hydraulic. When hydraulic fluid or pneumatic fluid flows into the power transmission unit 26, the displaceable arm 24 can be displaced towards the extended position, and when the hydraulic fluid or pneumatic fluid flows out of the power transmission unit 26, the displaceable arm 24 can be displaced towards the retracted position. Thus, the position of the vacuum gripper 22 can be adjusted to fit the shape of any part of the longitudinally bendable structure.

[0103] In some embodiments, the power transmission unit 26 can be pneumatic, where the fluid can be an inert gas or air.

[0104] In some embodiments, the power transmission unit 26 can be hydraulic, where the fluid can be a suitable hydraulic oil.

[0105] A vacuum can be formed at the vacuum gripper 22 by a vacuum pump 42 (not shown) connected to the vacuum gripper 22 to provide suction. The vacuum pump 42 can be connected to a local vacuum tank 40 to form a negative pressure between the vacuum gripper 22 and the surface of the longitudinally bendable structure, thereby adsorbing the vacuum gripper 22 to the surface of the longitudinally bendable structure. The local vacuum tank 40 can also ensure that suction can be provided even when power is lost, so that the clamping force will not be immediately lost even if the vacuum pump 42 can no longer provide suction. In addition, it is not necessary for the vacuum pump 42 to operate continuously because the local vacuum tank 40 will act as a buffer.

[0106] Figure 2 A shows a front view of a lifting device 10 for lifting a longitudinally bendable structure, such as a wind turbine blade. Figure 2 B is an enlarged view of a part of the lifting device 10.

[0107] The longitudinally bendable structure (not shown) can be any long and heavy bendable object, such as an aircraft wing or a roof, or a curved object, such as a wind turbine blade.

[0108] The lifting device 10 includes a longitudinal beam 12, the longitudinal beam including one or more segments and one or more rigging elements 14, wherein the longitudinal beam 12 can be positioned generally parallel to and above the longitudinally bendable structure to be lifted by the lifting device 10, thereby achieving balanced and stable lifting of the longitudinally bendable structure.

[0109] In some embodiments, the longitudinal beam 12 can include four segments and one or more rigging elements.

[0110] The longitudinal beam 12 may include beams with a length ranging from 5 m to 150 m, or from 10 m to 125 m, or from 25 m to 100 m, such as a beam of 40 m or 60 m. In some embodiments, the length of the longitudinal beam may be approximately equal to or longer than the length of the longitudinally bendable structure.

[0111] A plurality of attachment units 20( Figure 1 ) may be evenly distributed along the longitudinal beam 12, thereby obtaining a vacuum gripper 22 evenly distributed along the longitudinal beam.

[0112] In some embodiments, the end segments of the longitudinal beam 12 may include more attachment units 20 than the middle segment.

[0113] In some embodiments, the middle segment of the longitudinal beam 12 may include more attachment units 20 than the end segments.

[0114] In some embodiments, all segments of the longitudinal beam 12 may include the same number of attachment units 20.

[0115] By one or more vacuum pumps 42 connected to the vacuum gripper 22( Figure 3 and Figure 5 ) a vacuum can be formed at the vacuum gripper 22 to provide suction. Each vacuum gripper 22 may have one vacuum pump 42, or two or more vacuum grippers 22 may have a common vacuum pump 42. In Figure 5 the illustrated embodiment, a single vacuum pump 42 is used to provide suction for all the vacuum grippers 22 shown in Figure 5 .

[0116] One or more vacuum pumps 42 may be connected to a local vacuum tank 40 to create a negative pressure between the vacuum gripper 22 and the surface of the longitudinally bendable structure, thereby adsorbing the vacuum gripper 22 to the surface of the longitudinally bendable structure. The local vacuum tank 40 can also ensure that suction can be provided even when power is lost, so that the gripping force will not be immediately lost even if one or more vacuum pumps 42 are no longer able to provide suction. In addition, it is not necessary for one or more vacuum pumps 42 to operate continuously because the local vacuum tank 40 will act as a buffer.

[0117] In some embodiments, each attachment unit 20 may include a vacuum pump 42, thereby forming an effective vacuum at each vacuum gripper 22.

[0118] In some embodiments, a common vacuum pump 42 may be connected to one or more common vacuum tanks 50, the volume of the common vacuum tank 50 being 5 times, or 10 times, or 25 times larger than that of a single local vacuum tank 40. One or more common vacuum tanks 50 are in fluid communication with the local vacuum tanks 40. Subsequently, one or more vacuum pumps 42 pump the one or more common vacuum tanks 50 to create a vacuum in the one or more common vacuum tanks 50, which subsequently provides suction for the one or more local vacuum tanks 40, which in turn creates suction for the vacuum gripper 22. This ensures a negative pressure between the vacuum gripper 22 and the surface of the longitudinally bendable structure, which creates a strong and continuous adsorption during the lifting process.

[0119] Therefore, if the vacuum pump 42 loses power, the vacuum stored in the vacuum tanks 40, 50 maintains the negative pressure between the vacuum gripper 22 and the surface of the longitudinally bendable structure. This prevents the longitudinally bendable structure from falling during a short power outage.

[0120] In some embodiments, the lifting device 10 may include two common vacuum tanks 50.

[0121] The plurality of attachment units 20 includes a plurality of power transmission units 26, the power transmission units 26 being in fluid communication with the global power transmission system, where the fluid may be an inert gas, air, water, or oil.

[0122] The global power transmission system may include a fluid pump 32 for controlling the amount of fluid in the global power transmission system. The fluid pump 32 may be configured to increase or decrease the flow rate in the global power transmission system.

[0123] The global power transmission system and the power transmission units 26 may be in fluid communication through a common fluid tank, where the fluid volume may be adjustable or fixed. The adjustable fluid volume allows for the individual and independent displacement of the power transmission units 26, while the fixed fluid volume provides an interdependence between the power transmission units 26, where the displacement of one power transmission unit 26 is balanced by the other power transmission units 26.

[0124] The inflow and outflow of fluid from the common fluid tank 30 may be controlled by a valve 34 included in the global power transmission system. The valve 34 is displaced between an open state and a closed state, where in the open state, fluid flows into and out of the common fluid tank 30, and in the closed state, the inflow and outflow of fluid from the common fluid tank 30 is blocked. The valve 34 may be placed between the fluid pump 32 and the common fluid tank 30 or after the fluid pump 32, with the same effect. In some embodiments, in the case where the valve 34 is positioned downstream of the fluid pump 32, due to the possible presence of forward flow and backflow, the valve 34 will be two valves 34.

[0125] Thus, when the valve is in the open state, the fluid volume is adjustable, while when the valve is in the closed state, the fluid volume is fixed.

[0126] The entire fluid system consisting of the common fluid tank 30, the global power transmission system, and the power transmission unit 26 includes a constant and fixed total fluid volume. The fixed total fluid volume is divided into a first fluid volume and a second fluid volume. The first fluid volume is located between the common fluid tank 30 and the valve 34, and the second fluid volume is located between the valve 34 and the downstream-located power transmission unit 26. Thus, when the valve 34 is open, the fluid flows freely between the first fluid volume and the second fluid volume, which results in the first fluid volume and the second fluid volume being adjustable; while when the valve 34 is closed, the fluid flow between the first fluid volume and the second fluid volume is blocked, which results in the first fluid volume and the second fluid volume being fixed.

[0127] The global power transmission system can vary between two states. The connected state 130, in which the fluid volume is adjustable, and the lifted state 140, in which the fluid volume is fixed.

[0128] In the connected state 130, the fluid volume is adjustable, which allows the adjustment of the position of an individual vacuum gripper to the longitudinally bendable structure. The position of the vacuum gripper 22 can be controlled by the fluid flowing into the power transmission unit 26 to extend the displaceable arm 24 towards the longitudinally bendable structure, or by the fluid flowing out of the power transmission unit 26 to retract the displaceable arm away from the longitudinally bendable structure. Since the fluid volume is adjustable, the fluid volume flowing into and out of each individual power transmission unit 26 is independent of the fluid volume flowing into and out of other power transmission units 26. Therefore, each individual vacuum gripper 22 can be adjusted to a different displacement position without affecting the position of other vacuum grippers 22.

[0129] In the lifted state 140, the fluid volume is fixed, which creates an internal interdependence between the power transmission units 26 because all the power transmission units 26 are fluidly connected to each other through the global power transmission system. The fixed fluid volume causes a change in the fluid volume in one power transmission unit 26 to result in a reverse compensatory change in the fluid volume of other power transmission units 26.

[0130] When the longitudinally bendable structure bends during lifting, the vacuum gripper 22 located at the bending position is displaced in the bending direction. That is, if the longitudinally bendable structure bends away from the longitudinal beam 12, the displaceable arm 24 connected to the vacuum gripper 22 located at the bending position can extend; if the longitudinally bendable structure bends towards the longitudinal beam 12, the displaceable arm 24 connected to the vacuum gripper 22 located at the bending position can retract. The displacement causes a change in the fluid volume of the power transmission unit 26 located at the bending position, and this volume change causes other power transmission units 26 to be displaced in the direction to counteract the displacement caused by the bending and to the extent to counteract the displacement caused by the bending.

[0131] In the lifting state 140, the global power transmission system automatically adjusts the displacement of the fluid in the power transmission unit 26 according to the degree of bending of the longitudinally bendable structure. Thus, the global power transmission system can self-balance the power transmission unit 26, enabling the displaceable arm 24 to follow the bending movement of the longitudinally bendable structure.

[0132] The state of the global power transmission system can be controlled by the displacement of the valve 34 included in the global power transmission system, because the valve 34 controls the inflow and outflow of fluid from the common fluid tank 30 ( Figure 4 ). In the connected state 130, when the valve 34 is open, the fluid can flow in and out of the common fluid tank 30, while in the lifting state 140, when the valve 34 is closed, the inflow and outflow of fluid from the common fluid tank 30 are blocked, and the total fluid volume of the power transmission unit 26 is constant.

[0133] Thus, when the valve 34 is in the connected state 130, the fluid volume is adjustable, and when the valve 34 is in the lifting state 140, the fluid volume is fixed.

[0134] Figure 3 A shows a top view of the lifting device 10 for lifting a longitudinally bendable structure, such as a wind turbine blade. Figure 2 B is an enlarged view of a part of the lifting device 10, as Figure 2 shown and described.

[0135] Figure 3 C is an enlarged view of a part of the lifting device 10, which may include a fluid pump 32 connected to the common fluid tank 30. The fluid flowing in and out of the common fluid tank 30 can be controlled by the displacement of the valve 34 ( Figure 4 ) included in the global power transmission system. The valve 34 is displaced between the connected state 130 and the lifting state 140.

[0136] The valve 34 can be in a connected state 130, in which the valve 34 is open and fluid flows into and out of the common fluid tank 30, and in a raised state 140, in which the valve 34 is closed and blocks fluid from flowing into and out of the common fluid tank 30.

[0137] Thus, when the valve 34 is in the connected state 130, the fluid volume is adjustable, and when the valve 34 is in the raised state, the fluid volume is fixed.

[0138] Figure 4 The fluid communication between the common fluid tank 30, the global power transmission system, and the power transmission unit 26 is shown.

[0139] The entire fluid system composed of the common fluid tank 30, the global power transmission system, and the power transmission unit 26 includes a constant and fixed total fluid volume. The fixed total fluid volume is divided into a first fluid volume and a second fluid volume. The first fluid volume is located between the common fluid tank 30 and the valve 34, and the second fluid volume is located between the valve 34 and the power transmission unit 26 positioned downstream. Thus, when the valve 34 is open, the fluid flows freely between the first fluid volume and the second fluid volume, which results in the first fluid volume and the second fluid volume being adjustable; while when the valve 34 is closed, the fluid flow between the first fluid volume and the second fluid volume is blocked, which results in the first fluid volume and the second fluid volume being fixed.

[0140] The common fluid tank 30 can be in fluid communication with the global power transmission system and the power transmission unit 26, where the fluid volume can be adjustable or fixed. The inflow and outflow of fluid from the common fluid tank 30 can be controlled by the displacement of the valve 34 included in the global power transmission system. The valve 34 can be displaced between a connected state 130 and a raised state 140. In the connected state 130, the valve 34 is open and fluid flows into and out of the common fluid tank 30. In the raised state 140, the valve 34 is closed and blocks fluid from flowing into and out of the common fluid tank 30. The valve 34 can be placed between the fluid pump 32 and the common fluid tank 30 or after the fluid pump 32, and the effect is the same. In some embodiments, when the valve 34 is positioned downstream of the fluid pump 32, due to the possible presence of forward flow and reverse flow, the valve 34 will be two valves 34.

[0141] Thus, when the valve 34 is in the connected state 130, the fluid volume is adjustable, and when the valve 34 is in the raised state 140, the fluid volume is fixed.

[0142] In some embodiments, the fluid communication of each power transmission unit 26 can be controlled by a local fluid pump configured to control the inflow and outflow of fluid from the power transmission unit 26. Thus, the displacement of the displaceable arm 24 can be controlled.

[0143] In the connection state 130, the valve 34 can be opened and the fluid volume can be adjustable. This allows fluid to flow into and out of the global power transmission system and the power transmission unit 26, where the fluid flowing into the power transmission unit 26 causes the displaceable arm 24 to extend towards the longitudinally bendable structure, or the fluid flowing out of the power transmission unit 26 causes the displaceable arm 24 to retract away from the longitudinally bendable structure.

[0144] Since the fluid volume is adjustable, the fluid volume flowing into and out of each individual power transmission unit 26 is independent of the fluid volume flowing into and out of other power transmission units 26.

[0145] In the lifting state 140, the valve 34 can be closed and the fluid volume is fixed. This creates an internal interdependence between the power transmission units 26 because all the power transmission units 26 are fluidly connected to each other through the global power transmission system. The fixed fluid volume causes a change in the fluid volume in one power transmission unit 26 to result in a reverse compensatory change in the fluid volume of other power transmission units 26. Therefore, when the longitudinally bendable structure bends during lifting, the displaceable arm 24 located at the bend is displaced in the direction of the bend. That is, if the longitudinally bendable structure bends away from the longitudinal beam 12, the displaceable arm 24 located at the bend can extend; if the longitudinally bendable structure bends towards the longitudinal beam 12, the displaceable arm 24 located at the bend can retract. To accommodate the change in the fluid volume of the power transmission unit 26 located at the bend, a corresponding fluid volume can flow into or out of other power transmission units, causing the other power transmission units 26 to be displaced in the direction and to the extent that offsets the displacement caused by the bend.

[0146] Figure 5 and 6 show different perspective views of the lifting device 10 for lifting a longitudinally bendable structure, such as a wind turbine blade, as Figure 2 and Figure 3 shown and described.

[0147] Figure 6 shows a method 1000 for lifting a longitudinally bendable structure, such as a wind turbine blade. The method 1000 includes the step of providing 1100 the lifting device 10 ( Figures 1 - 5 ). During the positioning 1200 step, the lifting device 10 is positioned along the longitudinally bendable structure, where the longitudinal beam 12 of the lifting device 10 is positioned generally parallel to and above the longitudinally bendable structure.

[0148] The step of positioning 1200 is followed by the step of displacement 1300, in which a displaceable arm 24 that is substantially orthogonal to the longitudinal beam 12 (along the direction of the longitudinally bendable structure) linearly displaces between a retracted position and an extended position. The displacement of the displaceable arm 24 connected to the vacuum gripper 22 causes the vacuum gripper 22 to displace between a retracted position and an extended position.

[0149] The vacuum gripper 22 can be displaced to any position between a retracted position and an extended position.

[0150] The power transmission unit 26 displaces the displaceable arm 24, and the power transmission unit 26 can be pneumatic or hydraulic. When hydraulic or pneumatic fluid flows into the power transmission unit 26, the power transmission unit 26 displaces the displaceable arm 24 towards the extended position, and when hydraulic or pneumatic fluid flows out of the power transmission unit 26, the power transmission unit 26 displaces the displaceable arm 24 towards the retracted position.

[0151] The step of displacement 1300 can be a step of displacing 1300 the individual displaceable arms 24 connected to the vacuum gripper 22 independently of each other.

[0152] During the step of displacement 1300, the global power transmission system can be in a connected state 130, where the volume of the common fluid tank 30 is adjustable. The adjustable volume of the common fluid tank 30 allows the volume of fluid flowing into and out of each individual power transmission unit 26 to be independent of the volume of fluid flowing into and out of the other power transmission units 26. Thus, each individual vacuum gripper 22 can be adjusted to a different displacement position between a retracted position and an extended position without affecting the position of the other vacuum grippers 22. The step of displacement 1300 can adjust the vacuum gripper 22 to conform to the shape of the longitudinally bendable structure and engage with the surface of the longitudinally bendable structure, which is placed substantially parallel to the longitudinal beam 12 and below the longitudinal beam 12.

[0153] The method 1000 further includes the step of lifting 1400, in which the lifting device 10 lifts the longitudinally bendable structure. During the step of lifting 1400, the global power transmission system can form an internal interdependence between the power transmission units 26, where during lifting, the bending of the longitudinally bendable structure causes the displaceable arm 24 connected to the vacuum gripper 22 located at the bending site to displace in the direction of the bend. The displacement can be a displacement of the displaceable arm caused by a change in the volume of fluid in the power transmission unit 26. To counteract the bending movement of the entire longitudinally bendable structure to prevent the vacuum gripper 22 from losing its gripping force, the remaining displaceable arms 24 can displace in the direction and to the extent that offsets the displacement caused by the bend. The global power transmission system thus balances the power transmission units 26 such that the vacuum gripper 22 follows the bending movement of the longitudinally bendable structure.

[0154] During the 1400-step lifting process, the global power transmission system can be in the lifting state 140, where the volume of the common fluid tank 30 is fixed. The fixed volume of the common fluid tank 30 can form an internal interdependence among the power transmission units 26 because all the power transmission units 26 are fluidly connected to each other through the global power transmission system.

[0155] A change in the fluid volume in one power transmission unit 26 can cause a reverse compensatory change in the fluid volume of the other power transmission units 26. Therefore, when the longitudinally flexible structure bends during lifting, the vacuum gripper 22 located at the bend undergoes displacement in the bending direction. To accommodate the changes in the fluid volume of these power transmission units 26, the other transmission units 26 can undergo displacement in the direction that cancels out the displacement caused by the bending and to the extent that cancels out the displacement caused by the bending. Thus, during the 1400-step lifting process, the global power transmission system automatically adjusts the displacement of the fluid within the power transmission units 26 according to the degree of bending of the longitudinally flexible structure. Thereby, the global power transmission system can enable the power transmission units 26 to self-balance, allowing the displaceable arm 24 to follow the bending movement of the longitudinally flexible structure.

Claims

1. A lifting device (10) for lifting a longitudinally bendable structure, such as a wind turbine blade, the lifting device (10) comprising: - A longitudinal beam (12), the longitudinal beam (12) comprising one or more segments and one or more rigging elements (14); - A plurality of attachment units (20) positioned along the longitudinal beam; the attachment units (20) comprising: - A vacuum gripper (22) for gripping a portion of the longitudinally bendable structure; - A displaceable arm (24) connected to the vacuum gripper (22), the displaceable arm (24) being linearly displaceable between a retracted position and an extended position; - A power transmission unit (26) configured to displace the displaceable arm (24) between the retracted position and the extended position; - A global power transmission system in fluid communication with the power transmission unit (26), the global power transmission system being configured to balance the power transmission unit (26).

2. The lifting device (10) according to claim 1, characterized in that, The power transmission unit is pneumatic or hydraulic.

3. The lifting device (10) according to claim 1 or 2, characterized in that, The global power transmission system and the power transmission unit (26) share a common fluid tank (30).

4. The lifting device (10) according to claim 3, characterized in that, The global power transmission system varies between two states: - A connection state (130), in which the fluid volume in the common fluid tank (30) is adjustable, thereby enabling individual control of the power transmission unit (26); and - A lifting state (140), in which the fluid volume in the common fluid tank (30) is fixed, thereby enabling the power transmission unit (26) to self-balance by contracting and / or extending the displaceable arm (24).

5. The lifting device (10) according to claim 4, characterized in that, The global power transmission system may include a valve (34) downstream of the common fluid tank (30) and upstream of the power transmission unit (26), wherein the valve (34) is open when in the connection state (130) and closed when in the lifting state (140).

6. The lifting device (10) according to any one of claims 1 to 5, characterized in that, One or more vacuum grippers (22) may be attached to one or more displaceable arms (24) in an inclined manner.

7. The lifting device (10) according to any one of claims 1 to 6, characterized in that, The attachment unit (20) includes a local vacuum tank (40).

8. The lifting device (10) according to any one of claims 1 to 7, characterized in that, The longitudinal beam (12) includes a beam with a length ranging from 5 m to 150 m, or 10 m to 125 m, or 25 to 100 m, such as a 40 m or 60 m beam.

9. A method (1000) for lifting a longitudinally bendable structure, such as a wind turbine blade, the method (1000) comprising the steps of: - Providing (1100) a lifting device (10) according to one or more of claims 1 to 7; - Positioning (1200) the lifting device (10) along the longitudinally bendable structure; - Displacing (1300) the displaceable arm (24) using the power transmission unit (26) such that the vacuum gripper (22) engages with the surface of the longitudinally bendable structure; - Lifting (1400) the longitudinally bendable structure while using the global power transmission system to balance the power transmission unit (26).

10. The method (1000) according to claim 9, characterized in that, The step of displacement (1300) is performed when the global power transmission system is in the connection state (130), while the step of lifting (1400) is performed when the global power transmission system is in the lifting state (140).

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