Wind turbine blade lifting device
A new blade lifting device for lifting and handling wind turbine blades is described below. The blade lifting device may be used for both onshore and offshore applications, and may function as a yoke for supporting the wind turbine blade during transport, and during installation or replacement operations. Advantageously, the new blade lifting device may allow different types and sizes of blades to be lifted, whilst allowing the blade to be supported, for example, in a balanced horizontal position.
An illustrative embodiment of the blade lifting device according to this disclosure is shown in the Figures below, with Figure 1 showing a side view and Figure 2 showing an end on view.
The lifting device includes a blade gripper 1 which engages around the blade 10 near its root. In this embodiment, the blade gripper 1 comprises two sets of opposing clamping arms which can be closed to clamp around the body of the blade. The arms may include hinged members to adapt the geometry of various blades, and may be formed of steel, aluminium and/or carbon fibre, for example. In other embodiments different blade gripper arrangements may be provided. The blade gripper 1 forms a mechanical engagement, and applies a sufficient clamping force to frictionally retain the blade 10 in place and at the same time does not damage the blade. In this respect, the gripper 1 may be provided with sensors and a feedback system to control the pressure applied to the blade 10. The blade gripper 1 may be operated by, for example, hydraulic, pneumatic, or electrical actuators. The blade gripper 1 may therefore allow the blade to be interfaced directly from a trailer, vessel or a storage location without conflicting with existing equipment, such as existing transport equipment or storage structures. Replaceable interface pads may be provided on the blade gripper 1 to optimise the fit with specific blade types, when needed.
The blade gripper 1 connects to a longitudinal member 2 which is configured to align with the longitudinal axis of the blade when gripped by the blade gripper. The longitudinal member 2 may, for example, be formed of steel, aluminium and/or carbon fibre. The longitudinal member 2 forms a track for a moveable carriage or trolly 3 which is connected thereto. The moveable carriage 3 is controllably moveable along the longitudinal member 2, for example using a hydraulic or electrical actuator. The moveable carriage 3 allows the weight bearing point of the lifting device to be adjusted based on the centre of gravity of the blade 10. As such, the position of the moveable carriage may be adjusted to balance the blade. This allows, for example, different types of blades to be lifted and adjustments to be made for the tolerances between different individual blades. As such, the position of the blade 10 when suspended may be adjusted during the lifting operation by varying the balance point. A controller may be provided to make dynamic adjustments by controlling movement of the moveable carriage 3.
The upper surface of the moveable carriage 3 forms a controllable tether 4 for attachment to a lifting machine, such as a crane, arm, or ground transport device. The controllable tether 4 has four strands which, in this embodiment, are independently adjustable to allow the upper platform of the moveable carriage 3 to be tilted in lateral directions relative to the supporting attachment above. Each strand may be controlled by, for example, friction winches, or electrical or hydraulic actuators.
A power store may be provided on the device for powering the actuators, sensor and any control systems, where present.
In other embodiments, a tether-line system may additionally be provided for controlling horizontal movements of the device. For example, the longitudinal member 2 may be provided with tether points at each end, thereby allowing tether-lines to be connected for tethering the longitudinal member 2. Such tether-lines may be manually controlled, or connected to winches, traverse systems or drone system for controlling movements of the longitudinal member 2, and hence the blade connected thereto. For example, tether-line system may be used to restrict lateral and rotational movements during lifting operations.