Patent Description:
<CIT>) discloses a tool for handling wind turbine rotor blades. The tool comprises a connecting arrangement having means for connection to a wire connected to a crane or hoist for hoisting the tool and a rotor blade held by the tool. The tool further comprises gripping means for engagement of the blade surface, wherein the gripping means has two cooperating claw-shaped sets of gripping organs driven by actuators, where each set of gripping organs comprises a first claw shaped organ and a second claw shaped organ, which together in engaged position encloses the blade surface around the entire circumference of the blade. However, as the cradle support extends beyond the structural core of the rotor blade into the more fragile area near its trailing edge, any mishandling is more likely to cause blade damage.

<CIT>) discloses a rotor blade clamping tool having a first clamping element adapted to be arranged at a first side of the rotor blade and a second clamping element adapted to be arranged at a second side of the rotor blade. Each one of the first and second clamping elements includes a first balancing lever and a second balancing lever, each balancing lever being arranged pivotally about a pivot axis and having a first end flexibly connected with a corresponding first rotor blade contacting surface and a second end flexibly connected with a corresponding second rotor blade contacting surface, wherein the first and second rotor blade contacting surfaces are arranged end to end and form a common rectangular elongated rotor contacting surface. The first and second balancing levers of each clamping element are arranged side by side in parallel configuration, but mutually slightly angled about their longitudinal axes so that the common rectangular elongated rotor contacting surfaces of the respective first and second balancing levers may contact the respective side of the rotor blade surface on different positions along the chord line and conform to the angle of the surface at that particular position.

<CIT> discloses a clamp for clamping a blade for a wind turbine. The clamp comprises a first contact surface adapted to contact a portion of a back surface of the blade and a second contact surface adapted to contact a portion of a front face of the blade. The first and second contact surfaces of the clamp may be displaced relative to each other to allow removably receiving a blade therebetween. The first and second contact surfaces have an elongated rectangular shape and are each formed on a levelling piece having a wedge shaped form so that the contact surfaces may conform to the tapering shape of the rotor blade. However, it may be a disadvantage that the wedge shaped form of the levelling pieces has to be adapted to the specific shape of the rotor blades in question. As many different shapes of rotor blades exist, many different levelling pieces may have to be produced.

<CIT> A discloses a C-gripper for arranging at a cross-member or at a suspension element and a cross-member having at least one such C-gripper for transporting loads. The height of the C-gripper is adjustable.

The object of the present invention is to provide a rotor blade clamping tool better suitable for handling heavy rotor blades of many different shapes.

In view of this object, the at least one of the first and second clamping elements includes a main balancing lever being arranged pivotally about a main pivot axis and having a first end on which the corresponding first balancing lever is arranged pivotally about a corresponding first pivot axis and a second end on which the corresponding second balancing lever is arranged pivotally about a corresponding second pivot axis, and first and second balancing levers arranged on the same main balancing lever are aligned in their longitudinal direction.

In this way, by clamping the rotor blade exclusively in the lengthwise direction of the blade by means of four separate rotor blade contacting surfaces arranged successively in the lengthwise direction and by automatically adapting the angle of each single rotor blade contacting surface to the angle of the rotor blade surface at the respective particular position, the clamping tool may carry the rotor blade directly on the spar cap/shear web and thereby avoid the more fragile areas away from the structural core of the rotor blade. Thereby, very heavy rotor blades of different shapes may be handled by the clamping tool.

In an embodiment, the four separate rotor blade contacting surfaces of the at least one of the first and second clamping elements are adapted to be arranged successively in the lengthwise direction of the rotor blade.

In an embodiment, the clamping tool is provided with a hoisting attachment arranged so that, during hoisting, the first clamping element is adapted to be arranged at a generally upward side of the rotor blade, and the second clamping element is adapted to be arranged at a generally downward side of the rotor blade, and the distance between the first and second pivot axes of the main balancing lever of the second clamping element is longer than, preferably at least <NUM> times, more preferred at least <NUM> times, and most preferred about <NUM> times, the distance between the first and second pivot axes of the main balancing lever of the first clamping element. Thereby, the support on the lower side of the rotor blade may be distributed over a longer part of the rotor blade, and thereby the rotor blade may be supported in an even more stable way.

In an embodiment, the first clamping element includes the main balancing lever arranged pivotally about the main pivot axis, the second clamping element includes a crossbar arranged on the clamping mechanism and having a first end on which a corresponding first balancing lever is arranged pivotally about a corresponding first pivot axis and a second end on which a corresponding second balancing lever is arranged pivotally about a corresponding second pivot axis, the first and second balancing levers arranged on the crossbar are aligned in their longitudinal direction, and the crossbar is fixed against rotation in relation to the clamping mechanism about any axis extending at least substantially in parallel with the main pivot axis of the first clamping element. Because the crossbar is fixed against rotation in relation to the clamping mechanism about any axis more or less parallel with the main pivot axis of the first clamping element, the wind turbine blade may be held in a fixed orientation in relation to the rotor blade clamping tool. Thereby, the handling of the wind turbine blade by means of the clamping tool may be facilitated.

In an embodiment, the clamping tool is provided with a hoisting attachment arranged so that, during hoisting, the first clamping element is adapted to be arranged at a generally upward side of the rotor blade, and the second clamping element is adapted to be arranged at a generally downward side of the rotor blade.

In an embodiment, the first rotor blade contacting surface and the second rotor blade contacting surface of each balancing lever has the form of respective longitudinal contact elements being aligned in their longitudinal direction and being arranged at least substantially end to end, but with enough clearance to allow mutual movement, thereby forming a total rotor blade contacting surface of the respective balancing lever.

In an embodiment, on the first clamping element, the total rotor blade contacting surface of the first balancing lever and the total rotor blade contacting surface of the second balancing lever are arranged at least substantially end to end, but with enough clearance to allow mutual movement, and, on the second clamping element, the total rotor blade contacting surface of the first balancing lever and the total rotor blade contacting surface of the second balancing lever are spaced at a distance being greater than the length of the total rotor blade contacting surface of the first or second balancing lever of the first clamping element, and preferably greater than <NUM> per cent of, more preferred greater than <NUM> per cent of, and most preferred greater than <NUM> per cent of the combined length, on the first clamping element, of the total rotor blade contacting surface of the first balancing lever and the total rotor blade contacting surface of the second balancing lever. Thereby, the support on the lower side of the rotor blade may be distributed over a longer part of the rotor blade, and thereby the rotor blade may be supported in an even more stable way.

In a structurally particularly advantageous embodiment, the main balancing lever of the first clamping element includes a first and a second lever wall arranged in spaced and parallel configuration and being fixed to each other by means of a top plate and a bottom plate, and the corresponding first and second balancing levers extend at least partly between the first and second lever wall.

In another embodiment, each main balancing lever of the first and second clamping elements include a first and a second lever wall arranged in spaced and parallel configuration and being fixed to each other by means of a top plate and a bottom plate, and the corresponding first and second balancing levers extend at least partly between the first and second lever wall.

According to the invention, the clamping mechanism connecting the first clamping element and the second clamping element includes a rigid C-formed bracket having a first leg and a second leg. In an embodiment, a main bearing bracket for the main balancing lever of the first clamping element is hinged to the first leg of the C-formed bracket and is pivotal in relation to the first leg by means of a clamping actuator, and a main bearing for the main balancing lever of the second clamping element is arranged directly on the second leg of the C-formed bracket. Thereby, the clamping forces between the first clamping element and the second clamping element may be supported by means of a single rigid C-formed bracket which may be designed to a maximum load which may be determined based on the rotor blade to be carried. In this way, it may be avoided that the load is distributed over different brackets which each may have to be designed to a maximum load which may vary according to the way the rotor blade could be handled and therefore may have to be set relatively high.

In an embodiment, a main bearing bracket for a main balancing lever of the first clamping element is hinged to the first leg of the C-formed bracket and is pivotal in relation to the first leg by means of a clamping actuator, and the crossbar of the second clamping element is arranged on the second leg of the C-formed bracket by means of an exchangeable adapter piece bolted to the crossbar and arranged to maintain a certain angle between a longitudinal direction of the crossbar and an intermediate part of the rigid C-formed bracket connecting the first and second legs of the rigid C-formed bracket. Thereby, as for the embodiment mentioned above, the clamping forces between the first clamping element and the second clamping element may be supported by means of a single rigid C-formed bracket which may be designed to a maximum load which may be determined based on the rotor blade to be carried. In this way, it may be avoided that the load is distributed over different brackets which each may have to be designed to a maximum load which may vary according to the way the rotor blade could be handled and therefore may have to be set relatively high. Furthermore, by means of the exchangeable adapter piece bolted to the crossbar, an angle suitable for the specific wind turbine blade to be handled may be obtained between a longitudinal direction of the crossbar and an intermediate part of the rigid C-formed bracket. Thereby, the rigid C-formed bracket may for instance be handled with its intermediate part extending in an at least substantially vertical direction. Thereby, handling of the wind turbine blade may be facilitated.

In an embodiment, the exchangeable adapter piece is connected to the second leg of the C-formed bracket by means of a hinge having a hinge axis extending in the longitudinal direction of the crossbar so that the second clamping element is swingable between an insertion position for insertion of the rotor blade between the first and second clamping elements and a clamping position suitable for clamping the rotor blade between the first and second clamping elements. Thereby, insertion of the rotor blade between the first and second clamping elements may be facilitated.

In an embodiment, the second clamping element is swingable between the insertion position and the clamping position by means of a hydraulic actuator. Thereby, operation of the rotor blade clamping tool may be facilitated.

In an embodiment, the exchangeable adapter piece is adapted to be locked in the clamping position by means of a locking arrangement connecting the exchangeable adapter piece to the second leg of the C-formed bracket. Thereby, a hydraulic actuator for swinging the second clamping element between the insertion position and the clamping position may be dispensed with or such hydraulic actuator may not need to be dimensioned for carrying the clamping force of the rotor blade clamping tool.

In an embodiment, the intermediate part of the rigid C-formed bracket is provided with a transverse bar having opposed ends each being provided with a supporting piece adapted to support a leading edge or a trailing edge of a wind turbine blade held by the rotor blade clamping tool. Thereby, it may further be ensured that the rotor blade is held in a stable position by the clamping tool.

In an embodiment, the clamping tool is provided with a hoisting attachment in the form of a hoisting arm having a first end being connected to the clamping mechanism by means of a pivot element and a second end adapted to connect to a cable of a hoisting crane or the like, the pivot element allows pivotal movement of the hoisting arm in relation to the clamping tool about two different axes being at right angles to each other, and the hoisting arm is pivotal about said axes by means of a respective first and second hoist actuator. Thereby, the angle of the clamping tool and thereby the angle of the rotor blade carried by the tool may be varied during handling of the rotor blade so that, for instance, the blade may be positioned correctly in relation to the wind turbine hub when the blade is to be mounted thereon.

In a structurally particularly advantageous embodiment, the first leg of the C-formed bracket forms a fork element having a first leg and a second leg carrying a hinge axis therebetween on which the first clamping element is hinged to the first leg of the C-formed bracket, the first end of the hoisting arm is connected to the first leg of the fork element by means of the pivot element, the first hoist actuator is arranged between the second leg of the fork element and the hoisting arm, and the second hoist actuator is arranged between the first leg of the C-formed bracket or a central part of the fork element and the hoisting arm.

The invention will now be explained in more detail below by means of examples of embodiments with reference to the very schematic drawing, in which.

<FIG> and <FIG> show an embodiment of a rotor blade clamping tool <NUM> according to the present invention, for lifting a wind turbine rotor blade <NUM>. <FIG> illustrate another embodiment of the rotor blade clamping tool <NUM> according to the present invention. The clamping tool includes a first clamping element <NUM> adapted to be arranged at a first side <NUM> of the rotor blade <NUM> and a second clamping element <NUM> adapted to be arranged at a second side <NUM> of the rotor blade, as illustrated in <FIG>. A clamping mechanism <NUM> connects the first clamping element <NUM> and the second clamping element <NUM> and is adapted to open the clamping tool <NUM> for insertion of the rotor blade <NUM> between the first and second clamping elements <NUM>, <NUM> and close the clamping tool <NUM> for clamping the rotor blade <NUM> between the first and second clamping elements <NUM>, <NUM>.

In this embodiment, each one of the first and second clamping elements <NUM>, <NUM> includes a main balancing lever <NUM>, <NUM> being arranged pivotally about a main pivot axis <NUM>, <NUM> and having a first end <NUM> on which a corresponding first balancing lever <NUM> is arranged pivotally about a corresponding first pivot axis <NUM> and a second end <NUM> on which a corresponding second balancing lever <NUM> is arranged pivotally about a corresponding second pivot axis <NUM>. Each balancing lever <NUM>, <NUM> has a first end <NUM> flexibly connected with a corresponding first rotor blade contacting surface <NUM> and a second end <NUM> flexibly connected with a corresponding second rotor blade contacting surface <NUM>. As seen, those first and second balancing levers <NUM>, <NUM> which arranged on the same main balancing lever <NUM>, <NUM> are aligned in their longitudinal direction.

As illustrated in <FIG>, <FIG>, the flexible connection between each end <NUM>, <NUM> of the balancing levers <NUM>, <NUM> and the corresponding rotor blade contacting surface <NUM>, <NUM> has the form of a ball joint <NUM> with limited movement. The ball joint <NUM> is formed by a connection element <NUM> having a partly spherical head <NUM> arranged in a cylindrical bore <NUM> having a conical bottom <NUM>. A shaft <NUM> of the connection element <NUM> is arranged in a cylindrical bore <NUM> formed in the corresponding end <NUM>, <NUM> of the corresponding balancing lever <NUM>, <NUM>, and the cylindrical bore <NUM> in which the partly spherical head <NUM> of the connection element <NUM> is arranged is formed on the corresponding first or second longitudinal contact element <NUM>, <NUM> forming the corresponding rotor blade contacting surface <NUM>, <NUM>. The shaft <NUM> of the connection element <NUM> is adjustable in the longitudinal direction of the cylindrical bore <NUM> of the corresponding balancing lever <NUM>, <NUM> by means of a not shown screw inserted into a threaded hole <NUM> in the end of the shaft <NUM> of the connection element <NUM>. Furthermore, rotation of the shaft <NUM> of the connection element <NUM> in the cylindrical bore <NUM> is prevented by means of a key <NUM> fitting corresponding keyways of the shaft <NUM> of the connection element <NUM> and the cylindrical bore <NUM>. The partly spherical head <NUM> is maintained flexibly in the cylindrical bore <NUM> against the conical bottom <NUM> by means of a rubber ring <NUM> arranged above the head <NUM>. Furthermore, the movement of the ball joint <NUM> is limited by means of a pin <NUM> inserted through a corresponding bore extending through the partly spherical head <NUM>. The ends of the pin <NUM> are arranged in corresponding opposite grooves <NUM> formed longitudinally in the wall of the cylindrical bore <NUM> formed in the corresponding first or second longitudinal contact element <NUM>, <NUM> so that the pin <NUM> extends generally in the longitudinal direction of the corresponding longitudinal contact element <NUM>, <NUM>. In this way, the rotation of the ball joint <NUM> is limited to certain angles of rotation about the longitudinal axis of the shaft <NUM> and about an axis extending at right angles to the longitudinal axis of the shaft <NUM> and extending at right angles to the longitudinal direction of the corresponding longitudinal contact element <NUM>, <NUM>.

As seen in <FIG>, <FIG> and <FIG>, the clamping tool <NUM> is provided with a hoisting attachment <NUM> arranged so that, during hoisting, the first clamping element <NUM> is arranged at a generally upward side <NUM> of the rotor blade <NUM>, and the second clamping element <NUM> is arranged at a generally downward side <NUM> of the rotor blade <NUM>. Generally, according to the present invention, the four separate rotor blade contacting surfaces <NUM>, <NUM> of the first and second clamping elements <NUM>, <NUM> are adapted to be arranged successively in the lengthwise direction of the rotor blade. As seen, in the embodiment illustrated in <FIG> and <FIG>, the distance between the first and second pivot axes <NUM>, <NUM> of the main balancing lever <NUM> of the second clamping element <NUM> is longer than the distance between the first and second pivot axes <NUM>, <NUM> of the main balancing lever <NUM> of the first clamping element <NUM>. Preferably, the distance between the first and second pivot axes <NUM>, <NUM> of the main balancing lever <NUM> of the second clamping element <NUM> is at least <NUM> times, more preferred at least <NUM> times, and most preferred about <NUM> times, the distance between the first and second pivot axes <NUM>, <NUM> of the main balancing lever <NUM> of the first clamping element <NUM>.

As seen in <FIG>, the first rotor blade contacting surface <NUM> and the second rotor blade contacting surface <NUM> of each balancing lever <NUM>, <NUM> has the form of respective longitudinal contact elements <NUM>, <NUM> being aligned in their longitudinal direction and being arranged substantially end to end, but with enough clearance to allow mutual movement, thereby forming a total rotor blade contacting surface <NUM>, <NUM> of the respective balancing lever <NUM>, <NUM>. Each longitudinal contact element <NUM>, <NUM> is provided with a contact surface formed by a suitable material, such as rubber or the like, for achieving a suitably high friction between the longitudinal contact element <NUM>, <NUM> and the surface of the rotor blade. Alternatively, the contact surface may in fact by formed by one piece of flexible material extending over all contact elements <NUM>, <NUM> belonging to the respective main balancing lever <NUM>, <NUM>. Said contact surface may suitably be formed with ribs and/or grooves or the like therein in order to obtain better grip.

In the embodiment illustrated in <FIG>, the first clamping element <NUM> includes a main balancing lever <NUM> arranged pivotally about the main pivot axis <NUM> just as in the embodiment illustrated in <FIG>. However, in the embodiment illustrated in <FIG>, the second clamping element <NUM> includes a crossbar <NUM> arranged on the clamping mechanism <NUM> and having a first end <NUM> on which a corresponding first balancing lever <NUM> is arranged pivotally about a corresponding first pivot axis <NUM> and a second end <NUM> on which a corresponding second balancing lever <NUM> is arranged pivotally about a corresponding second pivot axis <NUM>. The first and second balancing levers <NUM>, <NUM> arranged on the crossbar <NUM> are aligned in their longitudinal direction. Furthermore, the crossbar <NUM> is fixed against rotation in relation to the clamping mechanism <NUM> about any axis extending at least substantially in parallel with the main pivot axis <NUM> of the first clamping element <NUM>. Because the crossbar <NUM> is fixed against rotation in relation to the clamping mechanism <NUM> about any axis more or less parallel with the main pivot axis <NUM> of the first clamping element <NUM>, the wind turbine blade may be held in a fixed orientation in relation to the rotor blade clamping tool <NUM>. Thereby, the handling of the wind turbine blade by means of the clamping tool <NUM> may be facilitated.

The clamping tool <NUM> illustrated in <FIG> is provided with a hoisting attachment <NUM> arranged so that, during hoisting, the first clamping element <NUM> is adapted to be arranged at a generally upward side <NUM> of the rotor blade <NUM>, and the second clamping element <NUM> is adapted to be arranged at a generally downward side <NUM> of the rotor blade <NUM>.

Furthermore, as seen in <FIG>, <FIG>, <FIG> and <FIG>, on the first clamping element <NUM>, the total rotor blade contacting surface <NUM> of the first balancing lever <NUM> and the total rotor blade contacting surface <NUM> of the second balancing <NUM> lever are arranged substantially end to end, but with enough clearance to allow mutual movement, whereas, on the second clamping element <NUM>, the total rotor blade contacting surface <NUM> of the first balancing lever <NUM> and the total rotor blade contacting surface <NUM> of the second balancing lever <NUM> are spaced at a distance D indicated in <FIG>. As further indicated, the total rotor blade contacting surface <NUM>, <NUM> of the first or second balancing lever <NUM>, <NUM> of the first clamping element <NUM> has a length L. In the illustrated embodiment, D is approximately <NUM>/<NUM> x L. Furthermore, as seen, the combined length, on the first clamping element <NUM>, of the total rotor blade contacting surface <NUM> of the first balancing lever <NUM> and the total rotor blade contacting surface <NUM> of the second balancing lever <NUM> is slightly more than <NUM>. According to the invention, it is preferred that D is greater than <NUM> per cent of, more preferred greater than <NUM> per cent of, and most preferred greater than <NUM> per cent of said combined length of <NUM>.

As seen in <FIG>, the main balancing lever <NUM> of the first clamping element <NUM> includes a first and a second lever wall <NUM>, <NUM> arranged in spaced and parallel configuration and being fixed to each other by means of a top plate <NUM> and a bottom plate <NUM>, and the corresponding first and second balancing levers <NUM>, <NUM> extend at least partly between the first and second lever wall <NUM>, <NUM>.

As seen in <FIG>, the clamping mechanism <NUM> connecting the first clamping element <NUM> and the second clamping element <NUM> includes a rigid C-formed bracket <NUM> having a first leg <NUM> and a second leg <NUM>. A main bearing bracket <NUM> for the main balancing lever <NUM> of the first clamping element <NUM> is hinged to the first leg <NUM> of the C-formed bracket <NUM> and is pivotal in relation to the first leg <NUM> by means of a clamping actuator <NUM>. A main bearing <NUM> for the main balancing lever <NUM> of the second clamping element <NUM> is arranged directly on the second leg <NUM> of the C-formed bracket <NUM>.

In the embodiment illustrated in <FIG>, the clamping mechanism <NUM> connecting the first clamping element <NUM> and the second clamping element <NUM> includes a rigid C-formed bracket <NUM> having a first leg <NUM> and a second leg <NUM>. A main bearing bracket <NUM> for a main balancing lever <NUM> of the first clamping element <NUM> is hinged to the first leg <NUM> of the C-formed bracket <NUM> and is pivotal in relation to the first leg <NUM> by means of a clamping actuator <NUM>. The crossbar <NUM> of the second clamping element <NUM> is arranged on the second leg <NUM> of the C-formed bracket <NUM> by means of an exchangeable adapter piece <NUM> bolted to the crossbar <NUM> and arranged to maintain a certain angle between a longitudinal direction of the crossbar <NUM> and an intermediate part <NUM> of the rigid C-formed bracket <NUM> connecting the first and second legs <NUM>, <NUM> of the rigid C-formed bracket <NUM>. The exchangeable adapter piece <NUM> is bolted to the crossbar <NUM> in that the exchangeable adapter piece <NUM> is provided with a number of bolt holes <NUM> on a flange <NUM> of the exchangeable adapter piece <NUM> corresponding to bolt holes <NUM> of the crossbar <NUM>. The flange <NUM> is further provided with a protrusion <NUM> matching a not shown corresponding recess of the crossbar <NUM>.

The exchangeable adapter piece <NUM> is connected to the second leg <NUM> of the C-formed bracket <NUM> by means of a hinge <NUM> having a hinge axis extending in the longitudinal direction of the crossbar <NUM> so that the second clamping element <NUM> is swingable between an insertion position for insertion of the rotor blade <NUM> between the first and second clamping elements <NUM>, <NUM> as illustrated in <FIG>, <FIG>, <FIG> and <FIG> and a clamping position suitable for clamping the rotor blade <NUM> between the first and second clamping elements <NUM>, <NUM> as illustrated in <FIG>, <FIG>, <FIG> and <FIG>. The hinge <NUM> is formed by insertion of a hinge pin <NUM> into hinge holes <NUM> of the second leg <NUM> of the C-formed bracket <NUM> and of the exchangeable adapter piece <NUM>, respectively.

The exchangeable adapter piece <NUM> is illustrated in further details in <FIG>.

In a not illustrated embodiment, the second clamping element <NUM> is swingable between the insertion position and the clamping position by means of a hydraulic actuator.

In the embodiment illustrated in <FIG>, the exchangeable adapter piece <NUM> is adapted to be locked in the clamping position by means of a locking arrangement <NUM> in the form of a locking pin <NUM> insertable into a locking hole <NUM> of the exchangeable adapter piece and a corresponding locking hole <NUM> of the second leg <NUM> of the C-formed bracket <NUM> and thereby connecting the exchangeable adapter piece <NUM> to the second leg <NUM> of the C-formed bracket <NUM>.

In the embodiment illustrated in <FIG>, the intermediate part <NUM> of the rigid C-formed bracket <NUM> is provided with a transverse bar <NUM> having opposed ends <NUM> each being provided with a supporting piece <NUM> adapted to support a leading edge or a trailing edge of a wind turbine blade held by the rotor blade clamping tool <NUM>.

By means of the exchangeable adapter piece <NUM> bolted to the crossbar <NUM>, an angle suitable for the specific wind turbine blade to be handled may be obtained between a longitudinal direction of the crossbar <NUM> and the intermediate part <NUM> of the rigid C-formed bracket <NUM>. Thereby, the rigid C-formed bracket <NUM> may for instance be handled with its intermediate part <NUM> extending in an at least substantially vertical direction as best illustrated in <FIG> and <FIG>. Thereby, handling of the wind turbine blade may be facilitated.

In the embodiments illustrated in <FIG> and in <FIG>, the clamping tool <NUM> is provided with a hoisting attachment <NUM> in the form of a hoisting arm <NUM> having a first end <NUM> being connected to the clamping mechanism <NUM> by means of a pivot element <NUM> and a second end <NUM> adapted to connect to a cable of a hoisting crane or the like by means of an eyebolt <NUM>. The pivot element <NUM> allows pivotal movement of the hoisting arm <NUM> in relation to the clamping tool <NUM> about two different axes <NUM>, <NUM> being at right angles to each other, and the hoisting arm <NUM> is pivotal about said axes by means of a respective first and second hoist actuator <NUM>, <NUM>. Thereby, the angle of the clamping tool <NUM> and thereby the angle of the rotor blade <NUM> carried by the tool <NUM> may be varied during handling of the rotor blade so that, for instance, the blade may be positioned correctly in relation to the wind turbine hub when the blade <NUM> is to be mounted thereon.

The first leg <NUM> of the C-formed bracket <NUM> forms a fork element <NUM> having a first leg <NUM> and a second leg <NUM> carrying a hinge axis <NUM> therebetween on which the first clamping element <NUM> is hinged to the first leg <NUM> of the C-formed bracket <NUM>. The first end <NUM> of the hoisting arm <NUM> is connected to the first leg <NUM> of the fork element <NUM> by means of the pivot element <NUM>, the first hoist actuator <NUM> is arranged between the second leg <NUM> of the fork element <NUM> and the hoisting arm <NUM>, and the second hoist actuator <NUM> is arranged between a central part <NUM> of the fork element <NUM> and the hoisting arm <NUM>.

In an alternative embodiment of the clamping tool <NUM> illustrated in <FIG> and in <FIG>, the clamping tool <NUM> may be adapted to be used in a not shown rotor blade hoisting system for installation and/or deinstallation of a rotor blade on a hub of a wind turbine, wherein the rotor blade hoisting system includes an upper cable support system adapted to be mounted on a top end of the wind turbine, a lower cable support system adapted to be arranged at a lower end of the wind turbine at a distance from the wind turbine, and at least a left and a right cable both adapted to be extended, in spaced relationship, between the upper cable support system and the lower cable support system. In this alternative embodiment of the clamping tool <NUM> according to the invention, the clamping tool <NUM> may be adapted to be arranged with the central part of the C-formed bracket <NUM> above the rotor blade <NUM>, the first leg <NUM> of the C-formed bracket to the left, at a first pressure or suction side of the rotor blade, and the second leg <NUM> of the C-formed bracket to the right, at a second pressure or suction side of the rotor blade. The hoisting attachment <NUM> may therefore be replaced by means of a left climbing system arranged on the first leg <NUM> of the C-formed bracket and adapted to climb on the left cable and a right climbing system arranged on the second leg <NUM> of the C-formed bracket and adapted to climb on the right cable, each of the left and the right climbing systems including at least a first and a second roller adapted to roll on the respective cable and adapted to, when the clamping system is clamped onto the rotor blade, be spaced in a longitudinal direction of the rotor blade so that the first rollers are placed nearer a root end of the rotor blade than the second rollers, and wherein at least one of the first and second rollers of each of the left and the right climbing systems is a motor driven roller. In this alternative embodiment of the clamping tool <NUM>, it may be preferred that, on both the first and second clamping elements <NUM>, <NUM>, the total rotor blade contacting surface <NUM> of the first balancing lever <NUM> and the total rotor blade contacting surface <NUM> of the second balancing lever <NUM> are spaced at a distance D indicated in <FIG>.

Claim 1:
A rotor blade clamping tool (<NUM>) for lifting a wind turbine rotor blade (<NUM>), the clamping tool consisting of a first clamping element (<NUM>) adapted to be arranged at a first side (<NUM>) of the rotor blade (<NUM>), a second clamping element (<NUM>) adapted to be arranged at a second side (<NUM>) of the rotor blade, and a clamping mechanism (<NUM>) connecting the first clamping element (<NUM>) and the second clamping element (<NUM>) and being adapted to open the clamping tool (<NUM>) for insertion of the rotor blade (<NUM>) between the first and second clamping elements (<NUM>, <NUM>) and close the clamping tool (<NUM>) for clamping the rotor blade (<NUM>) between the first and second clamping elements (<NUM>, <NUM>), the clamping mechanism (<NUM>) connecting the first clamping element (<NUM>) and the second clamping element (<NUM>) includes a rigid C-formed bracket (<NUM>) having a first leg (<NUM>) and a second leg (<NUM>), at least one of the first and second clamping elements (<NUM>, <NUM>) including a first balancing lever (<NUM>) and a second balancing lever (<NUM>), each balancing lever being arranged pivotally about a pivot axis (<NUM>, <NUM>) and having a first end (<NUM>) flexibly connected with a corresponding first rotor blade contacting surface (<NUM>) and a second end (<NUM>) flexibly connected with a corresponding second rotor blade contacting surface (<NUM>), and where at least one of the first and second clamping elements (<NUM>, <NUM>) includes a main balancing lever (<NUM>, <NUM>) being arranged pivotally about a main pivot axis (<NUM>, <NUM>) and having a first end (<NUM>) on which the corresponding first balancing lever (<NUM>) is arranged pivotally about a corresponding first pivot axis (<NUM>) and a second end (<NUM>) on which the corresponding second balancing lever (<NUM>) is arranged pivotally about a corresponding second pivot axis (<NUM>), in that first and second balancing levers (<NUM>, <NUM>) arranged on the same main balancing lever (<NUM>, <NUM>) are aligned in their longitudinal direction, and in that the four separate rotor blade contacting surfaces (<NUM>, <NUM>) of the at least one of the first and second clamping elements (<NUM>, <NUM>) are adapted to be arranged successively in the lengthwise direction of the rotor blade.