An extendable wind turbine blade for being extended in length during operation thereof, the wind turbine blade having an exterior surface with a root region and an airfoil region and comprising a first blade segment including a first portion of the exterior surface, a second blade segment including a second portion of the exterior surface, and a connection mechanism connecting the blade segments, and being configured to bring the wind turbine blade to a retracted state, in which the portions of the exterior surface are flush and adjoining, when the wind turbine blade operates above a threshold rotational speed and to bring the wind turbine blade to an extended state, in which the portions of the exterior surface are disconnected and the blade length is at least 101% of the blade length in the retracted state, when the wind turbine blade operates below the threshold rotational speed.

An actuator device for a wind turbine, in particular for a rotor blade of a wind turbine, and also to an associated wind turbine and a method of assembly, with an actuator component and a control component, wherein the actuator component has at least one actuator layer with a preferential direction and, substantially parallel to the actuator layer, at least one exciting layer, wherein the actuator layer comprises a photoactuator, wherein the photoactuator is designed to change a strain and/or stress of the actuator layer in the preferential direction on the basis of excitation light, wherein the exciting layer is designed to guide excitation light into the actuator layer, wherein the control component comprises a light source and a light guide, wherein the light source is arranged away from the exciting layer and is connected to the exciting layer by means of the light guide and wherein the light guide runs in different directions through the exciting layer.

A wind-turbine rotor blade, comprising a blade root and a blade tip, a flange arranged on the blade root side for fastening the rotor blade to a rotor hub of a wind turbine, and a pitch bearing for adjusting the angle of attack of the rotor blade. The rotor blade has a non-pitched carrier, on which the flange is embodied, wherein the pitch bearing is fastened to the carrier and is spaced apart from the flange toward the blade tip.

An actuator device for a wind turbine, in particular for a rotor blade of a wind turbine, and also to an associated wind turbine and a method of assembly, with an actuator component and a control component, wherein the actuator component has at least one actuator layer with a preferential direction and, substantially parallel to the actuator layer, at least one exciting layer, wherein the actuator layer comprises a photoactuator, wherein the photoactuator is designed to change a strain and/or stress of the actuator layer in the preferential direction on the basis of excitation light, wherein the exciting layer is designed to guide excitation light into the actuator layer, wherein the control component comprises a light source and a light guide, wherein the light source is arranged away from the exciting layer and is connected to the exciting layer by means of the light guide and wherein the light guide runs in different directions through the exciting layer.

A synchronizing assembly including: a synchronizing ring having a countersunk orifice; and a bumper assembly comprising: a bumper at least partially enclosing a cavity, the bumper comprising an outward side, an inward side opposite the outward side, a first side extending between the outward side and the inward side, a first opening on the outward side extending into the bumper to define a first portion of the cavity; and a second opening on the first side extending into the bumper to define a second portion of the cavity; and a bolt comprising a bolt head and a bolt shank, wherein the bolt shank extends through the first opening and the bolt head is secured within the second portion of the cavity, wherein the bumper further comprises a raised boss extending away from the outward surface, the raised boss configured to mate with the countersunk orifice of the synchronizing ring.

A synchronizing assembly including: a synchronizing ring having a countersunk orifice; and a bumper assembly comprising: a bumper at least partially enclosing a cavity, the bumper comprising an outward side, an inward side opposite the outward side, a first side extending between the outward side and the inward side, a first opening on the outward side extending into the bumper to define a first portion of the cavity; and a second opening on the first side extending into the bumper to define a second portion of the cavity; and a bolt comprising a bolt head and a bolt shank, wherein the bolt shank extends through the first opening and the bolt head is secured within the second portion of the cavity, wherein the bumper further comprises a raised boss extending away from the outward surface, the raised boss configured to mate with the countersunk orifice of the synchronizing ring.

A wind-turbine rotor blade, comprising a blade root and a blade tip, a flange arranged on the blade root side for fastening the rotor blade to a rotor hub of a wind turbine, and a pitch bearing for adjusting the angle of attack of the rotor blade. The rotor blade has a non-pitched carrier, on which the flange is embodied, wherein the pitch bearing is fastened to the carrier and is spaced apart from the flange toward the blade tip.

A pitch actuator for a wind turbine pitch system, the pitch actuator having an actuator rod, a drive end of which is defined by a clevis fork arrangement having first fork member and a second fork member that extend in a direction along a rod axis and terminate at a tip end. The first and second fork members define respective clevis openings for receiving a clevis pin therethrough, said clevis openings each having an opening perimeter profile comprising: a first perimeter section defined by a leading circular arc that is centred on the rod axis and oriented in the direction of the tip end of the fork members, the circular arc defining a nominal radius and a central angle of less than 120 degrees, and second and third flared perimeter sections that flank respective sides of the first perimeter section, each of which define an enlarged clearance zone with respect to at least part of an imaginary circle defined by the nominal radius of the first perimeter section. A benefit of the invention is that the enlarged clearance zones defined by the flared perimeter sections create an area where there is no contact between the perimeter of the openings and the outer surface of the clevis pin. This provides a stress relieving function since deformation of the openings in use, due to force applied along the axis of the actuator rod, does not create a point of stress combined with sliding or rubbing movement with the sides of the clevis pin, thereby reducing wear and fatigue. The invention extends to a pitch system including such a pitch actuator and a wind turbine incorporating such a pitch system.

A pitch actuator for a wind turbine pitch system, the pitch actuator having an actuator rod, a drive end of which is defined by a clevis fork arrangement having first fork member and a second fork member that extend in a direction along a rod axis and terminate at a tip end. The first and second fork members define respective clevis openings for receiving a clevis pin therethrough, said clevis openings each having an opening perimeter profile comprising: a first perimeter section defined by a leading circular arc that is centred on the rod axis and oriented in the direction of the tip end of the fork members, the circular arc defining a nominal radius and a central angle of less than 120 degrees, and second and third flared perimeter sections that flank respective sides of the first perimeter section, each of which define an enlarged clearance zone with respect to at least part of an imaginary circle defined by the nominal radius of the first perimeter section. A benefit of the invention is that the enlarged clearance zones defined by the flared perimeter sections create an area where there is no contact between the perimeter of the openings and the outer surface of the clevis pin. This provides a stress relieving function since deformation of the openings in use, due to force applied along the axis of the actuator rod, does not create a point of stress combined with sliding or rubbing movement with the sides of the clevis pin, thereby reducing wear and fatigue. The invention extends to a pitch system including such a pitch actuator and a wind turbine incorporating such a pitch system.