The present invention relates to a structural vibration damper with a pendulum mass and an eddy current damper acting thereon, wherein the pendulum mass is designed in the manner of a carriage with at least two rolls and is mounted to be movable on at least one curved rail, wherein the pendulum mass is displaced from an equilibrium position along the at least one curved rail upon vibration excitation.

Structural vibration dampers (hereinafter also referred to as dampers or vibration dampers) are generally used in structures that tend to vibrate due to their shape, location or even a particular load, in order to reduce these vibrations. The structures can be of any type. Typically, however, they are tall and slender structures such as towers, chimneys or wind turbines. The vibrations of the structure in question can be the result of a wide variety of loads. They can result from excitation by wind, traffic or, in the case of offshore wind turbines, by waves.

Of course, dampers require installation space. Depending on the structure, this can be a problem. Wind turbines in particular offer little space for accommodating dampers. The generic structural vibration damper discussed here is a damper with a relatively compact design. This is because its pendulum mass is designed in the form of a carriage with rolls, which is mounted so that it can travel on curved rails. Compared with a classic vibration damper in the form of a rope pendulum, this form of dampers offers the advantage that no rope is used. This reduces the vertical dimension of the vibration damper. Furthermore, with rope-pendulum type vibration dampers there is the (theoretical) risk that the pendulum mass could fall down and damage the structure if the rope tears.

A generic vibration damper, i.e. one with a pendulum mass in the form of a movable carriage, is disclosed in EP 2 746 483 A1 , for example. In this case, the natural frequency of the vibration damper can be adapted to the respective structure by a specific arrangement of the curved rails and the rolls on the pendulum mass at different height levels. In addition, this vibration damper has an eddy current brake that reduces the displacement of the damper. However, a disadvantage of this known damper is that it still requires a relatively large amount of installation space, especially for large vibrations.

This is because in order to be able to damp vibrations of extreme events, even the generic structural vibration dampers require a lot of installation space, since the pendulum mass still functions in the manner of a pendulum and thus the at least one curved rail must be dimensioned as large that the maximum conceivable displacement of the pendulum dimensions still takes place safely on the rail. Otherwise, the mass would travel beyond the end of the rail, hit the structure, derail or alternatively bump against a frame of the damper. Such an impact must also be avoided urgently, since it would introduce an additional vibration into the structure.

In order to give a clear definition of what is to be understood by a vibration from a specific event or load case, reference shall be made here to the European Standard EN 1990. This standard regulates the basic principles and requirements for the structural safety, serviceability and durability of load-bearing structures of buildings. This is because structures are generally exposed to different loads during their working life. A distinction is made between everyday loads and extreme loads. The everyday loads are those loads that occur relatively frequently during use and that a structure must be able to withstand permanently for its designed working life. These everyday loads are those loads which, according to the understanding of EN 1990, occur up to the serviceability limit state. Generally, no visible damage to the structure may occur up to the serviceability limit state.

In addition, however, loads can also occur as a result of extreme events whose resulting loads exceed everyday or typical service load cases. According to the understanding of EN 1990, a structure must also be able to withstand such extreme loads up to a certain level before failure of the structure occurs. The condition just before the failure of the structure is referred to in EN 1990 as the ultimate limit state. The extreme events can be, for example, earthquakes, fires, explosions, storm surges or an impact against the structure. The limit states must be determined individually for each structure.

The invention is therefore based on the task of providing a structural vibration damper that has a more compact design and at the same time is also suitable for damping large vibrations as a result of extreme events.

The problem is solved with a generic structural vibration damper which, according to the invention, has a first displacement range and at least one second displacement range. The damping properties of the structural vibration damper differ in the first displacement range from those in the second displacement range. As a result, the damping properties in the first displacement range can be designed for vibrations up to the serviceability limit state, while the damping properties in the second displacement range can be designed for larger vibrations, for example up to the ultimate limit state.

Further, the structural vibration damper has at least a third displacement range, wherein the damping properties of the structural vibration damper in this displacement range differ from those of at least one other displacement range. In this way, an even finer adjustment of the damping properties can be made.

Further, the at least one curved rail has a different radius of curvature in at least one displacement range than in one of the other displacement ranges. For example, in the second displacement range, the incline of the at least one curved rail may be greater than in the first displacement range. Then, the pendulum mass must overcome a greater incline per distance when displacing into the second displacement range than in the first displacement range. This leads to a higher damping at larger displacements, as they occur at larger vibration excitations.

Expediently, the radii of curvature of the at least one curved rail vary in at least two displacement ranges. Thus, the radii of curvature are not constant in these two displacement ranges. For example, the clothoid-type radius of curvature may decrease toward the end of the curved rail so that the incline in the second displacement range increases toward the ends of the at least one curved rail. The damping then increases more strongly with greater displacement in the second displacement range.

Further, the eddy current damper has at least one magnet arranged on and/or in the pendulum mass and an electrical conductor arranged parallel to the at least one curved rail. With the arrangement of the magnet on and/or in the pendulum mass, the occupied installation space can be reduced in the vertical direction. Also, with such an arrangement, no electrical conductors need to be laid in the pendulum mass. This simplifies the construction of the pendulum mass and improves the operational reliability of the overall device, since there is no heavy load in the lines or cables due to the movement of the pendulum mass.

It has further been shown to be advantageous if the electrical conductor of the eddy current damper has a different, preferably larger, width in at least one displacement range than in the other displacement ranges. The different width of the electrical conductor in the displacement ranges changes the width of the air gap between the magnet of the pendulum mass and the electrical conductor. In the displacement range where the electrical conductor is wider and the air gap is consequently narrower, stronger eddy currents are induced within the electrical conductor. As a result, the displacement of the pendulum mass in this displacement range is damped more strongly than in a displacement range in which the electrical conductor has a smaller width. The change in width between the displacement ranges can also be continuous, thus avoiding a sudden increase or decrease in damping. Also, it can be expedient, if the width of the electrical conductor changes in a displacement range in which the at least one curved rail has a constant radius of curvature. In this way, the damping force of the eddy current damper can increase or decrease with a constant curved rail.

However, it is also conceivable that the width of the electrical conductor changes at a point where the radius of curvature of the at least one curved rail also changes. Thus, the damping force of the eddy current damper and the radius of curvature of the curved rail can change together, e.g. increase or decrease.

It may be useful for an end stop to be located at each end of the at least one curved rail. The end stop generates a stiffness force and/or a damping force on the pendulum mass upon contact with the pendulum mass. The end stop prevents the pendulum mass from displacing beyond the ends of the at least one curved rail in the event of large displacements and, for example, from falling off the rail, as a result of which the structural vibration damper would no longer fulfill its function and the structure would possibly be damaged. By generating a stiffness force and/or a damping force, the displacement of the pendulum mass is slowed down and not abruptly terminated, so that no additional vibrations are generated by the impact of the pendulum mass against the end stop.

Further, the structural vibration damper has a braking device with which the pendulum mass can be braked and/or blocked. This braking device is used, for example, to brake and block the pendulum mass in its equilibrium position in order to prevent displacement during maintenance work, for example, so as not to endanger the maintenance personnel.

Preferably, a controllable part of the braking device is arranged on a frame of the structural vibration damper and/or on the structure. This means that no controllable parts are required on the pendulum mass. Wiring of the controllable part on the pendulum mass can thus be omitted. This increases operational safety.

Further, the controllable part of the braking device has at least one actuator and at least one brake pad, which is arranged on a beam with which the actuator is operatively connected. The at least one brake pad can be brought into contact with at least one friction counterpart arranged on the pendulum mass for braking. The beam is movable in this case. The at least one brake pad, which is arranged on the beam in such a way that it can come into contact with the friction counterpart when the actuator moves the beam, can reliably brake and/or block the pendulum mass. The brake pad can be designed, for example, as a bare metal plate, a coated plate or a rubberized plate. Expediently, the beam is movably mounted on the structural vibration damper in such a way that it can be pivoted and/or displaced by the actuator for braking. For example, the beam can be movably mounted on both sides and moved by the actuator in such a way that the brake pad arranged on the beam can be brought into contact with the friction counterpart for braking.

Further, the beam can be lifted at least on one side by the actuator for braking. The beam can thus also be rotatably mounted on one side and moved by the actuator on the other side, so that the brake pad arranged on the beam comes into contact with the friction counterpart. Such an arrangement makes it possible to implement a braking device in a simple manner.

Alternatively or additionally, the beam can be pivoted and/or displaced by the actuator by means of an intermediate movable beam assembly. Due to the intermediate beam assembly the actuator is not directly connected to the beam. Thus, the actuator can be arranged with a different orientation or spaced from the beam and still be able to reliably pivot and/or move the beam. The intermediate beam assembly can thereby consist of several beams connected in an articulated manner, which form a toggle lever, for example. The intermediate beam assembly can be movably mounted on the structure, on the frame and/or on a separately provided support.

Further, the friction counterpart is attached to the pendulum mass via at least one spring or designed as a leaf spring. If the brake pad of the braking device is brought into contact with the friction counterpart, the springs or the friction counterpart designed as a leaf spring are compressed or deformed. The stiffness of the springs or the leaf spring allows the dimensioning of the contact force between the brake pad and the friction counterpart. Both the brake pad and the friction counterpart can be designed, for example, as a bare metal plate, a coated plate or a rubberized plate.

Further, the pendulum mass has a lower height on the outside than on the inside. The lower height on the outside of the pendulum mass means that it can be designed in such a way that the structural vibration damper has the smallest possible vertical dimension over the entire travel distance of the pendulum mass and does not collide with the structure. The structural vibration damper can thus be made more compact.

It can be useful that at least one guide roll is additionally arranged on the pendulum mass, which is arranged laterally and/or below the rail in such a way that a lurching of the pendulum mass is at least reduced. This improves the smooth running of the pendulum mass during travel on the at least one rail and reduces wear on the guide rolls due to reduced lurching. This increases the working life of the structural vibration damper. In the following, the invention is explained in more detail with the aid of examples of embodiments shown in drawings. These show schematically:

Fig. 1 A a section through a first embodiment of a structural vibration damper according to the invention with end stops with a pendulum mass in equilibrium position as well as an indicated pendulum mass in maximum displacement;

Fig. 1 B a top view of the structural vibration damper with end stops shown in Fig. 1A;

Fig. 2 a section through a second embodiment of a structural vibration damper according to the invention;

Fig. 3 a cross-section of a pendulum mass of a structural vibration damper according to the invention, with a first embodiment of a braking device arranged on the outside of the pendulum mass;

Fig. 4 a cross-section of a pendulum mass of a structural vibration damper according to the invention with a second embodiment of a braking device arranged within the pendulum mass;

Fig. 5 a side view of a pendulum mass of a structural vibration damper according to the invention with a third embodiment of a braking device arranged below the pendulum mass and having two vertically arranged actuators;

Fig. 6A a side view of a pendulum mass of a structural vibration damper according to the invention with a fourth embodiment of a braking device in the unbraked state, which is arranged below the pendulum mass and has a vertically arranged actuator;

Fig. 6B a side view of the pendulum mass shown in Fig. 6A with structural vibration damper according to the invention with a fourth embodiment of a braking device in the braked state;

Fig. 7 A a side view of a pendulum mass of a structural vibration damper according to the invention with a fifth embodiment of a braking device in the unbraked state, which is arranged below the pendulum mass and has a horizontally arranged actuator; Fig. 7B a side view of the pendulum mass shown in Fig. 7A with structural vibration damper according to the invention with a fifth embodiment of a braking device in the braked state;

Fig. 8A a side view of a pendulum mass of a structural vibration damper according to the invention with a sixth embodiment of a braking device in the unbraked state, which is arranged below the pendulum mass and has a horizontally arranged actuator coupled to a movable beam assembly; and

Fig. 8B a side view of the pendulum mass shown in Fig. 8A with structural vibration damper according to the invention with a sixth embodiment of a braking device in the braked state.

Alike components or elements are given the same reference signs within the figures.

Figs. 1A and 1 B show a structural vibration damper 1 of a first embodiment according to the invention, which has a pendulum mass 2 that is movably mounted on four rolls 4 on two curved rails 5. Inside the pendulum mass 2, a magnet 6 of an eddy current damper 3 is arranged adjacent to an electrical conductor 7 without contacting it. The electrical conductor 7 is not shown in Fig. 1 A for reasons of clarity. The electrical conductor 7 is arranged parallel and between the rails 5, so that the magnet 6 is spaced from the electrical conductor 7 with a defined air gap when the pendulum mass 2 is moved. Due to this arrangement of the eddy current damper 3, eddy currents are induced in the electrical conductor 7 when the pendulum mass 2 is displaced, which generate a magnetic field opposite to the magnetic field of the magnet 6 and thus damp the displacement of the pendulum mass 2.

According to the invention, the ends of the electric conductor 7 in Fig. 1 B are thicker in the displacement range s2 in the horizontal direction than in the displacement range s1 . As a result, the damping characteristics of the eddy current damper 3 in the displacement range s2 differ from those in the displacement range s1 , since a stronger damping effect occurs due to a reduction in the air gap between the magnet 6 and the electric conductor as a result of the thickening of the electric conductor 7. End stops 8 are arranged at the ends of the rails 5 so that the pendulum mass 2 cannot travel beyond the ends of the rails 5. In Fig. 1A, a pendulum mass 2 is shown with dash lines, which is in the outermost position and thus contacts the end stop 8. The contacted end stop 8 is thereby compressed. By compressing the end stop 8, kinetic energy of the pendulum mass 2 is converted so that the pendulum mass 2 is decelerated. A friction counterpart 16 is arranged on the underside of the pendulum mass 2, which a controllable part 10 of a braking device 9 can contact in order to brake or block the pendulum mass 2. The controllable part 10 is thereby arranged on the frame 11 of the structural vibration damper 1 , which is arranged on the structure 12. Electrical cables for controlling the controllable part 10 are thus attached to the frame 1 1 and/or to the structure 12.

Fig. 2 shows a structural vibration damper 1 of a second embodiment. Here, the electrical conductor 7 is not shown for reasons of clarity as well. In contrast to the first embodiment, the structural vibration damper 1 of the second embodiment has a different radius of curvature of the curved rail 5 in the second displacement range s2 than in the first displacement range s1. This also results in changed damping characteristics in the displacement range s2 compared to those in the displacement range s1 . In this case, the radius of curvature of the curved rail 5 is not constant in the second displacement range s2, but the incline of the curved rail 5 increases toward the ends. As a result, the displacement of the pendulum mass 2 is damped more strongly in the displacement range s2 than in the displacement range s1. No end stops 8 are arranged at the ends of the curved rail 5 in the second embodiment example. The incline prevents displacement beyond the end of the curved rail 5, so that no end stops 8 are necessary. The braking device 9 is arranged within the pendulum mass 2. The frame 11 of the structural vibration damper 1 is designed lower than in the first embodiment due to the smaller vertical dimension of the pendulum mass 2 with the braking device 9. The pendulum mass 2 is rounded on its underside such that the pendulum mass 2 does not come into contact with the structure 12 during travel on the rail 5.

Fig. 3 shows a cross-section of a pendulum mass 2 which is mounted on the rails 5 so that it can be moved by means of rolls 4. In addition, two guide rolls 18 are arranged on the pendulum mass 2, which contact the rails 5 laterally from the inside and thus reduce or prevent the pendulum mass 2 from lurching during displacement. A magnet s in the form of a horseshoe magnet is arranged inside the pendulum mass 2, the legs of which are arranged at a distance next to an electrical conductor 7 so that an air gap is formed between the legs of the magnet 6 and the electrical conductor 7. Two actuators 13 with brake pads 14 of a braking device 9 of a first embodiment attached thereto are arranged on the structure 12, which can contact two friction counterparts 16 provided on a recess of the pendulum mass 2.

The pendulum mass 2 shown in Fig. 4 differs from that shown in Fig. 3 primarily with regard to the location where the braking device 9 is arranged. The braking device 9 shown is a braking device of a second embodiment. Here, a friction counterpart 16 is arranged in a T-shape in a recess within the pendulum mass 2, which is located below the magnet 6 and the electrical conductor 7. Two actuators 13 arranged on the structure protrude into the recess of the pendulum mass 2 so that two brake pads 14, each arranged on one of the two actuators 13, can be brought into contact with the vertical part of the friction counterpart 16. A side view of a pendulum mass 2 with a third embodiment of a braking device 9 is shown in Fig. 5. A friction counterpart 16 is arranged via two springs 17 on the underside of the pendulum mass 2, which is movably mounted on a rail 5 by means of rolls 4. Two actuators 13 are arranged on the structure 12, on which a brake pad 14 is located, which can be brought into contact with the friction counterpart 16. If the brake pad 14 is pressed against the friction counterpart 16 via the two actuators 13, the pendulum mass 2 is braked. In the process, the two springs 17 are compressed and thus generate a force that presses the friction counterpart 16 against the brake pad 14.

Fig. 6A shows a side view of a pendulum mass 2 according to the invention with a fourth embodiment of a braking device 9 in the unbraked state. The braking device 9 shown differs from that shown in Fig. 5 in that a brake pad 14 is arranged on a beam 15, which is supported on one side by a movable beam assembly 19 and on the other side via an actuator 13. Both the movable beam assembly 19 and the actuator 13 are thereby arranged on the structure 12. The actuator 13 is in a retracted position, as a result of which the brake pad 14 arranged on the beam 15 does not come into contact with the friction counterpart 16.

Fig. 6B shows the pendulum mass according to the invention illustrated in Fig. 6A with a fourth embodiment of a braking device 9 in the braked state. Here, the actuator 13 is in an extended position. As a result, the beam 15 pivots in such a way that the brake pad 14 comes into contact with the friction counterpart 16. The pendulum mass 2 is thereby braked and/or blocked and the displacement thus reduced or prevented.

Fig. 7A shows a side view of a pendulum mass 2 with a fifth embodiment of a braking device 9 in the unbraked state. In the braking device 9 of the fifth embodiment, the friction counterpart 16 is designed as a leaf spring, which is arranged directly on the underside of the pendulum mass 2. By designing it as a leaf spring, additional installation space can be saved in the vertical direction, since the friction counterpart 16 can be arranged more closely to the pendulum mass 2. The actuator 13 is arranged horizontally and extended in the unbraked state. As a result, the beam 15, which is connected to the actuator 13 on one side and to the movable beam assembly 19 on the other side, is at an angle. Due to this inclined position, the brake pad 14, which is arranged on the beam 15, does not come into contact with the friction counterpart 16.

Fig. 7B shows the pendulum mass 2 according to the invention shown in Fig. 7A with a fifth embodiment of a braking device 9 in the braked state. In this case, the actuator 13 is in a retracted position, as a result of which the beam 15 has shifted and pivoted to a horizontal position. In the braked state, the brake pad 14 is in contact with the friction counterpart 16, so that the pendulum mass is braked and/or blocked. In the process, the friction counterpart 16, which is designed as a leaf spring, is deformed. The deformation of the friction counterpart 16 produces a counterforce that additionally presses the friction counterpart 16 against the brake pad 14.

Fig. 8A shows a side view of a pendulum mass 2 with a sixth embodiment of a braking device 9 in the unbraked state. Here, the friction counterpart 16 is designed as a leaf spring arranged on the underside of the pendulum mass as well. The brake pad 14 is arranged on the beam 15 in such a way that it can be brought into contact with the friction counterpart 16. The beam 15 is connected on one side to the movable beam assembly 19 and on the other side to an additional beam 20. The additional beam 20 is thereby fixedly connected to the structure 12. The actuator 13, which is arranged horizontally on the structure 12, is in a retracted position and connected to the movable beam assembly 19. The movable beam assembly 19 is thereby arranged on a support 21 , which is connected to the structure 12, in such a way that a horizontal movement of the actuator 13 is displaced so that the beam 15 pivots. In the unbraked state, the brake pad 14 does not come into contact with the friction counterpart 16.

Fig. 8B shows the pendulum mass 2 according to the invention illustrated in Fig. 8A with a sixth embodiment of a braking device in the braked state. Here, the actuator 13 is extended so that the brake pad 14 is pivoted with the beam 15. As a result, the brake pad 14 comes into contact with the friction counterpart 16, so that in the braked state the displacement of the pendulum mass 2 is braked and/or blocked.

REFERENCE SIGNS

Structural vibration damper

Pendulum mass

Eddy current damper

Driving roll

Curved rail

Magnet

Electrical conductor

End stop

Braking device

Controllable part

Frame

Structure

Actuator

Brake pad

Beam

Friction counterpart

Spring

Guide roll

Movable beam assembly

Additional beam

Support

First displacement range

Second displacement range