The subject of the following invention is the vertical axis wind turbine brake, high-powered, ensuring safe braking of the rotor in every condition, especially in situations of emergency and putting the rotor out of action.

High-powered vertical axis wind turbines are characterized by long moments of inertia (M.I.) of the rotation movement, which is mainly due to large masses of airfoils located at large distances from the rotation axis. Safety of operation in conditions of such high kinetic energy requires specific solutions in the range of rotor bearing which usually consists in an additional (apart from shaft bearing in the turbine column) rolling rotor support directed axially with rollers located on the larger diameter. There are many solutions of this type. Some of them are described in patent specifications, i.e. US 4168439, US 20110176919, and in the Polish invention specification P-390976. In these solutions, the rotor is provided with at least two, vertically oriented blades spaced circumferentially at equal central angles connected with lower ends or in the centre of gravity zones where they are connected to the turbine shaft by horizontal arms. The blades or the arms are rigidly connected to the rotor shaft through a coaxial ring raceway, wherein the raceway is supported on at least three rollers spaced apart with an equal central angle. In solution P-390976, the lower and upper wings are radially swept - externally and at an angle from the rotation axis. The upper and lower wings are connected to the shaft through arms attached at the centre of gravity of the airfoil. The arms are connected with each other through a ring raceway with a horizontal rolling surface and an airfoil attachment diameter ranging from 0.1 up to 0.9. At least three roller assemblies, mounted on the support structure anchored to the ground over at least three tower columns, mate with the raceway. The structure of high-powered wind turbines includes disc brakes. This is presented in detail in solutions according to patent specifications PL168561 , US 20110299975 and KR 20120097131. In these solutions, brake shoes are pressed against the horizontal surfaces of the discs or the vertical surfaces of the ring using pads.

According to the invention, the wind turbine brake is adapted to a turbine whose rotor has substantially vertical blades mounted to the ends of the horizontal arms connected to the rotor shaft at an equal central angle spacing. The arms are rigidly connected to the rotor shaft with a horizontal coaxial ring raceway which connects the arms in zones located at approximately half their length. The raceway is supported on at least three rollers spaced in relation to an equal central angle. The essence of the invention lies in the fact that the rollers are attached to rotor supports using lifting mechanisms. On the supports there are brake pads directed towards the rolling surface of the raceway.

It is beneficial if the structure of rotor arms is flexible and deformable in a vertical direction with specifically chosen parameters - in the conditions of a maximum speed of the rotor and rollers lowered to the non-contact position with the raceway - the bending stress pattern in the arms corresponds to the pressure force of the ring raceway on the brake pads - the value of the pressure force makes the total moment of torque larger than the moment of wind pressure on the rotor blades.

Apart from taking advantage of arm elasticity when braking, it is also preferred to apply a solution in which the arms are connected to the shaft through joints in the horizontal plane perpendicular to the shaft axis and oriented perpendicularly to the radii of the centres of gravity of each blade set and an arm connected to it.

In the next preferred solution, the rotor supports are brackets rigidly connected to the turbine tower.

In a solution according to the invention, rotor braking occurs as a result of one-sided pressure of the ring raceway against the brake pads. If the rollers are lowered to the non-contact position with the raceway, the pressure and the required braking torque are obtained as a result of an elastic deformation of the arms loaded with a component of the resultant force of the rotor weight, the centrifugal force and the wind pressure or only under the effect of this component force and a swept-down deflection of the arms mounted to the shaft using joints. The obtained moment of torque, whose value is higher than the value of wind pressure exerted on the rotor blades, allows for an emergency deceleration of the rotor under conditions of approaching the maximum rotary speed and putting the turbine out of action.

According to the invention, the brake is explained in the description of two model realizations in a schematic view shown in the figure. According to the first realization, the brake with its arms rigidly connected to the shaft is shown in Figures 1 up to 4. Figure 1 shows a side view of the turbine, Figure 2 - top view, Figures 3 and 4 - cross sections according to lines AA and BB in Figure 2 for the situations of propelling and braking. The second model realization of the brake with its arms connected to the shaft through joints is shown in Figures 5, 6 and 7 which show, respectively: Figure 5 - a top view, Figure 6 - a side view of one of the arms, Figure 7 - a perspective view of the connection of the arms with the turbine shaft using joints.

According to the first realization, the turbine has three blades (1 ) spaced at the central angle of 120° where each blade (1 ) has a shape formed of two wings radially swept-externally at an angle up and down. Blades (1) in the middle between the wings and in the horizontal plane passing through their centres of gravity are connected to the turbine shaft (3) using two horizontal arms (2). On approximately half of their length, the arms (2) are rigidly connected to the rotor shaft (2) with the coaxial ring raceway (4). The raceway (4) is supported on four rollers (5) mounted using lifting mechanisms (9) on supports (6) in a form of brackets rigidly connected to the turbine tower (7). The lifting mechanisms (9) have a kinematic rocker system propelled with an in-built piston hydraulic actuator (Fig. 3) which can be located under the support (6) as well (Fig. 4). The rollers (5) are installed inside the supports (6) which have the shape of channel arms directed upwards. The top edges of each arm of the supports (6) have brake pads (8) mounted. The lifting mechanism (9) extends the rollers (5) in the top position over the working surfaces of the brake pads (8). This allows for the rolling operation of the rollers (5) with the ring raceway (4) according to Figure 3. In the lower position, the rollers (5) are lowered below the surface of the brake pads (8) (Fig. 4) and as a result of the elastic deformation of the arms (2) the raceway (4) is lowered and its pressure on the brake pads (8) occurs. The structure of the rotor arms (2) is elastically deformed in a vertical direction. The stiffness of the arms (2) is specifically selected - in the conditions of the maximum speed of the rotor n _max with rollers (5) lowered to the lower position, the bending stress pattern in the arms (2) corresponds to pressure force N of the ring raceway (4) on the brake pads (8) with a value making the total moment of torque Mt greater than the moment of pressure M _p of wind on the rotor blades (1 ).

In the second model brake realization according to the invention, shown in Figures 5, 6 and 7, the rotor arms (2) are connected to the shaft (3) using joints (10) whose axes are located in the horizontal plane Pp which is perpendicular to the shaft axis (3) and are oriented perpendicularly to the radii of the centres of gravity C of each blade set (1 ) and an arm (2) connected to it. The situation in the first realization is identical. The arms (2) on a radius sized approximately half the length of the arms (2) are rigidly connected to the horizontal ring raceway (4), which is coaxial with the rotor shaft (2). The lower rolling surface Pt of the raceway (4) is swept-externally downwards from the horizontal plane at an angle a with its vertex in the joint axis (10). The raceway (4) is also supported on four rollers (5) attached using the lifting mechanisms (9) to supports (6) in a form of brackets rigidly connected to the turbine tower (7) on the upper edges of which there are mounted brake pads (8). The upper torque surface of the brake pads (8) is inclined at an angle that ensures adhesion to the lower rolling surface Pt of the raceway (4) of the arms (2) swept-downwards in relation to the joint axis (10). After lowering the rollers (5), the required braking torque of a value higher than the value of wind pressure on the blades (1 ) is obtained through downward inclination of the arms (2) under the weight of the rotor and the pressure of the lower rolling surface Pt of the raceway (4) on the brake pads (8).