Adaptive tuned mass damper for damping low excitation frequencies

Abstract

The invention relates to a new type of tuned mass damper which is suitable in particular for damping oscillations of a low frequency, and can thus be used preferably as a construction damper when building or siting high, narrow structures, such as wind-turbine towers. The invention relates in particular to a pendulum oscillation damper having a first pendulum, to which the mass is attached, and a second pendulum, which is formed by a spring-like support device of a different design and is operated using a gas-air volume such that, with the aid thereof, the frequency of the oscillation system can be adapted and adjusted.

Claims

1. An adaptive pendulum-tuned mass damper for adaptable damping of occurring oscillations of low frequencies <2 Hz in high, narrow structures, comprising: at least one first pendulum rod, which has a length, is arranged perpendicularly in the idle state, and is connected at one end via a joint directly or via a carrier element to a structure to be damped; at least one second pendulum rod, which has a length, is arranged perpendicularly in the idle state, is arranged entirely or partially below or above the first pendulum rod, and is connected at one end via a joint directly or via the carrier element to the structure to be damped; wherein said first pendulum rod has a free end that is connected via a freely movable joint directly or indirectly to a free end of the second pendulum rod; an oscillation mass, which is attached to the first pendulum rod and connected via the freely movable joint to the second pendulum rod such that the first and the second pendulum rods are moved together when force acts on the oscillation mass; and a pressure-controlled support device configured to increase or reduce a weight of the oscillation mass by relieving or loading such that frequency changes are selectively achieved, wherein the support device is an integral component of the second pendulum rod.

2. The adaptive pendulum-tuned mass damper according to claim 1, wherein the support device is operated with a gas/air volume which is under a pressure that brings about a change in the weight of the oscillation mass, wherein said gas/air volume is provided in a gas/air container, which is completely an integral component of the support device or is partially mounted separately therefrom.

3. The adaptive pendulum-tuned mass damper according to claim 2, wherein the gas/air volume is selected such that less than 10% of the volume is displaced or shifted by the support device during a pendulum movement of the tuned mass damper.

4. The adaptive pendulum-tuned mass damper according to claim 1, wherein the support device is an air spring element or a pneumatic cylinder.

5. The adaptive pendulum-tuned mass damper according to claim 4, wherein the air spring element is an elastic bellows or an arrangement of several elastic bellows stacked one above the other, a roller bellows, or an arrangement of roller bellows arranged one behind the other.

6. The adaptive pendulum-tuned mass damper according to claim 5, wherein the elastic bellows or the arrangement of elastic bellows has a small cross-section in relation to the gas volume.

7. The adaptive pendulum-tuned mass damper according to claim 1, wherein the length of the at least one first pendulum rod is different from the length of the second pendulum rod.

8. The adaptive pendulum-tuned mass damper according to claim 7, wherein the at least one first pendulum rod is 50-100% shorter or longer than the at least second pendulum rod.

9. The adaptive pendulum-tuned mass damper according to claim 1, wherein the at least first pendulum rod entirely or partially constitutes an upper pendulum, and the at least second pendulum rod entirely or partially constitutes a lower pendulum, and the two pendulum rods are interconnected via a common joint.

10. The adaptive pendulum-tuned mass damper according to claim 1, wherein the at least first pendulum rod entirely or partially constitutes a lower pendulum, and the at least second pendulum rod entirely or partially constitutes an upper pendulum, and the two pendulum rods are interconnected via a common joint.

11. The adaptive pendulum-tuned mass damper according to claim 1, wherein the joint is a Cardan joint.

12. The adaptive pendulum-tuned mass damper according to claim 1, wherein the joint is a ball joint.

13. The adaptive pendulum-tuned mass damper according to claim 1, wherein the support device has a guide rod.

14. The adaptive pendulum-tuned mass damper according to claim 1, further comprising a pressure-regulating unit which compensates for pressure fluctuations, which are caused by changed external conditions during operation, by increasing or lowering the pressure of the gas/air volume via a port when preset limit values are reached.

15. The adaptive pendulum-tuned mass damper according to claim 1, wherein the oscillation mass is attached to the first pendulum rod such that a center of gravity of the oscillation mass is in proximity to the freely movable joint or is identical thereto.

16. The adaptive pendulum-tuned mass damper according to claim 15, wherein the oscillation mass is three-dimensionally designed such that there is a correspondingly-shaped free space, into which the second pendulum rod at least partially extends with its joint, and space for pendulum movements in the operating state is provided.

17. The adaptive pendulum-tuned mass damper according to claim 1 is configured as a two-dimensional transverse damper, wherein the oscillation mass is connected via two or more joints to the same number of first pendulum rods of equal length and via the freely movable joint connected to the second pendulum rod so that the oscillation mass is movable in the horizontal plane.

18. The adaptive pendulum-tuned mass damper according to claim 1, further comprising at least one further damping unit, which is mounted on the joint of the first pendulum rod and/or on a circumference of the oscillation mass.

19. The adaptive pendulum-tuned mass damper according to claim 18, wherein the at least one further damping unit is a rotational damper.

20. The adaptive pendulum-tuned mass damper according to claim 1, wherein the adaptive pendulum-tuned mass damper is mounted on a mobile carrier structure, which is reversibly attached to a structure during erection or deconstruction of the structure.

21. A wind turbine comprising a nacelle, a rotor, and a tower, wherein the wind turbine has an adaptive pendulum-tuned mass damper according to claim 1, which is permanently or temporarily attached outside or inside, in or to the tower or to or in the nacelle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, the invention is explained with reference to the example embodiments illustrated in the figures, which show:

(2) FIG. 1a: a side view of a pendulum-tuned mass damper according to an embodiment the invention;

(3) FIG. 1b: a side view of the embodiment according to FIG. 1a rotated by 90?;

(4) FIG. 1b1: a top plan view of FIG. 1b;

(5) FIGS. 1c, 1c1: further details of a support device according to the embodiment of FIG. 1a;

(6) FIGS. 1d, 1d1: a further embodiment of a pendulum-tuned mass damper according to the invention including an elastic bellows;

(7) FIG. 1e: a further embodiment of the pendulum-tuned mass damper according to the invention including a pneumatic cylinder;

(8) FIGS. 2a-2c: show various perspective views of the embodiment of the pendulum-tuned mass damper according to FIG. 1 with an air spring unit;

(9) FIGS. 3a-3c: show various views of a further embodiment of the pendulum-tuned mass damper according to the invention;

(10) FIG. 4a: shows another embodiment of the damper according to FIG. 3;

(11) FIG. 4b: a side view of the pendulum-tuned mass damper according to FIG. 4a;

(12) FIG. 4c: shows a sectional view of embodiment of the pendulum-tuned mass damper according to FIG. 4a;

(13) FIG. 4d: shows a perspectival view of the embodiment of the pendulum-tuned mass damper according to FIG. 4c;

(14) FIG. 5: shows an embodiment of the pendulum-tuned mass damper according to the invention with a pneumatic cylinder; and

(15) FIG. 6: shows an embodiment of the pendulum-tuned mass damper according to the invention with an air spring unit.

DETAILS OF THE INVENTION AND DESCRIPTION OF THE EMBODIMENTS

(16) As already explained in the introduction, it is necessary to raise or relieve the mass continuously over the entire oscillation path, with only minimal influence of other forces, in order to, for example, reduce the weight of a specific pendulum mass and thus the frequency. This is accomplished according to the invention by a counter pendulum (5) which acts on the mass from below, for example. This counter pendulum is conceived and designed as a support device (7) or at least as an air spring unit (7.1).

(17) The use of an air spring unit (7.1) in the form of an air-filled elastic bellows or of a package made of stacked elastic bellows (7.1.1), or as a pneumatic cylinder (7.1.2), is suitable here. However, a spring unit made of steel bellows can also be used.

(18) However, it should be noted that, when a closed bellows filled with gas (for example, air) is used, the force changes during the oscillation path, which is similar to a spring, as a result of which the oscillating frequency is increased again to the same extent.

(19) According to the invention, an appropriate air spring is therefore used, which is connected to an air or gas volume and can be compressed by supplying gas/air. If the air volume is large enough in comparison to the volume of the air spring unit, the compression of the air no longer has any considerable influence.

(20) If the entire air volume V of the supporting spring unit, which is composed of the volume of the gas reservoir V1 and the volume V2 displaced by the air spring, is quite large in comparison to the displaced volume V2, the quotient (V1+V2)/V1 approaches the number 1 such that the compression of the air has no or only a small influence on the existing stiffness of the supporting spring. With the same V2, the quotient assumes smaller values by increasing V1. If, for example, 4 L are displaced by the pendulum movement, and the content of the tank is 80 L, (V1+V2)/V1=84/80=1.05, which corresponds to a sufficiently small force amplitude. If V1 is increased to 100 L, a value of 1.04 is achieved. This means that, during a pendulum movement, 5 or 4% of the total gas volume is displaced by the air spring unit (7.2).

(21) Ideally, the gas storage tank (7.5) is integrated into the lower pendulum rod. However, a separate additional tank, co-oscillating or stationary, can also be used to receive the air volume. This additional tank must then be connected by means of an appropriate pipeline to the air spring unit (7.1). In the case of a co-oscillating reservoir, this can be a fixed pipeline. In the case of a separately mounted reservoir, a flexible tube (7.10) is required.

(22) With a large force application to or relief of the mass (1) by the lower pendulum rod (5), for example, the mass tends to evade the force, which results in a circular movement of the pendulum, and thus in turn in an increase in frequency which is undesirable here. It is therefore advantageous to keep the first pendulum rod (4) significantly shorter or longer than the second pendulum rod (5). The pendulum restoring force of the first pendulum rod is thus greater than that produced by the force of the transverse component occurring on the second pendulum rod, so that a linear oscillating movement is again achieved. It has now been shown that it is advantageous to design the second pendulum rod (5) with the support device (7), for example, to be longer by a factor of 1.5 to 2 than the upper pendulum rod (4). However, it is also possible to make the second pendulum rod (5) correspondingly shorter.

(23) The natural frequency of the system is reduced by raising or relieving the mass via the gas pressure. If the bellows becomes pressure-less, the frequency of the first (short) pendulum (4) is achieved. With 0.8 m pendulum length (4.1), for example, the pressure-less frequency of the system is approximately 0.56 Hz. This frequency can be reduced by injecting gas (air) into the system. For example, a frequency of 0.1 Hz can be achieved at a pressure having the effect of approximately 70% of the weight of the pendulum. The frequency can also be influenced by the pendulum length (4.1). Thus, the system can be used as a frequency-adaptive damper.

(24) In specific embodiments of the support device (7), e.g., with the pneumatic cylinder (7.2), it is, conversely, also possible, by means of pressure against the oscillation mass (1), to increase the weight thereof relatively, which leads to a (relative) increase in the natural frequency of the oscillation of the pendulum. The oscillation system can thus be adjusted in terms of frequency to both higher and lower values.

(25) In the case of oscillations with variable frequency, such as wave excitation by wind turbines or also ships and other offshore constructions, the frequency of the excitation can be measured by sensors, and the system can also be adapted, proportionally to this frequency, to the disturbance frequency by varying the air pressure in the support devices (7).

(26) FIGS. 1 (a-e) show various embodiments of the invention, which each have a (first) upper pendulum rod and a second (lower) pendulum rod (5), wherein the support device is designed as part of the second (lower) pendulum rod, and has either an air spring unit (7.1), in the form of an elastic bellows (7.1.1) or roller bellows (7.1.2), or, alternatively, a pneumatic cylinder (7.2).

(27) FIG. 1(a) is a side view of the pendulum-tuned mass damper according to the invention. The oscillation mass (1) is on an upper first pendulum rod. The joint (4.3)(5.2) connects the first pendulum rod to a second, lower pendulum rod (5) having the length (5.1). The oscillation mass (1) is in this case designed on its underside such that it not only surrounds the upper part of the supporting spring unit (7) but also leaves such a large amount of free space (8) that it can participate in the pendulum movements without abutting. For this purpose, a corresponding bore or recess can be provided in the mass, but the mass can also be joined together from correspondingly shaped and arranged individual elements around the free space (8).

(28) The upper pendulum rod (4) with the length (4.1) has an upper joint (4.2), via which it is connected to the carrier unit of the system (not shown). In this embodiment, the upper joint is a Cardan joint, into which a rotational damper (3) is additionally integrated. Such a damper joint is known, for example, from WO 2019/201471. In principle, however, simple and undamped joints, such as ball joints, can also be used (FIG. 2). The upper pendulum is formed by the length between the rotational axes of the Cardan joint and the center of gravity (2) of the mass (1), which center of gravity is preferably located in proximity to the joint (4.3)(5.2) or is identical thereto. The lower pendulum rod (5) having the length (5.1) is represented by the support device (7). The support device in this case comprises an air spring unit (7.1) with integrated gas/air containers (7.5), in which a gas/air mixture (7.6)(7.6.1) is located. The container (7.5) is tapered in the upper part (7.5.1) so that this part can be inserted more or less deeply into the free space (8) of the mass (1) and is freely movable there together with the pendulum rod (5). The pendulum rod (5) ends in the upper part with the joint (5.2)(4.3). In the optimal case, the position of this joint should be at the center of gravity (2) of the mass.

(29) The support device (7), as an integral component of the lower pendulum rod (5), has, at the lower end, a further jointpreferably a ball jointwhich establishes the connection to the structure to be damped or to the carrier element (6) of the structure. However, the connection to the carrier unit is not shown here.

(30) The different lengths (4.1)(5.1) of the pendulum rods (4) and (5) also emerge from the drawing.

(31) FIG. 1(b) is a side view, rotated by 90?, of the embodiment of FIG. 1(a).

(32) In addition, a carrier arrangement or a carrier frame (6) is shown here, which is connected via the joints (4.2) and (5.3) to the complete pendulum-tuned mass damper according to the invention.

(33) FIG. 1(b1) is a plan view of FIG. 1(b), and specifically a Cardan joint with connection to a carrier structure (6), wherein the Cardan joint is equipped with two rotational damper units (3) which are arranged offset to one another at a 90? angle.

(34) FIG. 1(c)(c1) shows further details of the support device (7) according to the invention of FIG. 1(a). The component is composed of the container or reservoir (7.5) for receiving a gas or air volume (7.6) via an inlet/outlet device (7.10). The container (7.5) is divided here into an upper, narrower container part (7.5.1) with a corresponding volume (7.6.1) and a larger, lower container part (7.5) with the volume (7.6). The two container parts are interconnected in terms of pressure via a gas passage (7.7.1). Instead of the division into an upper, small and a lower, larger compartment, it is also possible to use a single continuous, but upwardly tapered container in order to have sufficient space in the free space (8) in the region of the mass (1).

(35) Arranged in the lower region of the support device (7) is the air spring unit (7.1), which is connected in terms of pressure by a lower gas passage (7.7)(7.7.2) to the container (7.5) or via an upper gas passage (7.7)(7.7.1) to the additional container (7.5.1). In this variant, the air spring unit (7.1) comprises three elastic bellows (7.1.1) which, when pressure changes in the containers (7.5)(7.5.1), expand or are compressed correspondingly in the vertical direction, and thus cause the weight of the mass (1) (not shown here) positioned above and attached to the pendulum rod (4) to change correspondingly.

(36) Usually, 1 to 15, and preferably 3 to 10, such bellows stacked on top of one another are used, to enable the required reduction in the weight of the mass (1). Ultimately, this depends upon the mass, the volumes (7.6)(7.6.1), and the volume displaced by the elastic bellows.

(37) The lower end of the support device (7) in turn has a ball joint (5.3), which is connected to the carrier structure of the oscillation system (not shown here).

(38) In this embodiment, the support device (7) conceived as a supporting spring unit also has a guide rod (7.4), which serves to provide sufficient stability to the component, since it would otherwise bend in the region of the bellows under load. The guide rod (7.4) is preferably guided in sliding bearings (7.3)(7.7), wherein, in the specific case, an upper sliding bearing (7.3.1) between lower container (7.5) and upper container (7.5.1) and a lower sliding bearing (7.3.2) between air spring unit (7.1.1) and lower container (7.5) are used.

(39) The air port (7.10) can be connected in any position of the air-filled or gas-filled space (7.6)(7.6.1). It is advantageous to mount it in the lower region of the supporting spring unit, in which little movement takes place. At the same time, a further container for increasing the volume can be connected by means of a tube or a pipe connection. A further inlet/outlet device (7.10), which has a regulating unit (7.11), is provided at the lower end of the supporting spring unit. In the simplest case, this is a regulating valve.

(40) The supporting spring unit described here functions in such a way that, by a vertical change of the volume of the elastic bellows (7.1.1), the part of the superjacent unit with the gas/air container (7.5)(7.5.1) is pushed along the guide rod (7.4) in the direction of the joint (5.2). Since the joint (5.2), which is preferably designed as a ball joint, is here identical to the joint (4.3) of the upper first pendulum rod (4) to which the oscillation mass (1) is attached, the corresponding compressive or tensile force is thus exerted on the oscillation mass (1), so that a targeted frequency adaptation to the oscillation system can thereby be carried out.

(41) Another possibility is to install an automatic pressure-regulating unit, with the aid of which the preset pressure in the spring system (7) can be adapted manually or automatically, and possibly with the aid of sensors, to the changed natural frequency when the external conditions in the oscillation system change. On the one hand, this has the advantage that pressure changes caused by possible temperature fluctuations, for example, can be compensated for. Furthermore, the natural frequency of the tuned mass damper can be continuously adapted to the requirements via such a regulating device (adaptive operation). The pressure-regulating unit for maintaining a constant air pressure can, for example, consist of a pressure sensor, a three-way servo valve, and a compressor. The pressure sensor continuously monitors the pressure in the container (7.5)(7.5.1). The control advantageously takes into account only the maximum pressure which is produced whenever upper and lower pendulum rods are in line with one another, and thus the smallest air volume in the movement sequence is used for regulating. It is also recommended that the adaptation be carried out automatically only if specific maximum or minimum limit values are exceeded or undershot. The regulation compares this pressure to the predetermined setpoint value and opens or closes the valve accordingly in order to increase or decrease the gas pressure in the container via a compressor or via compressed-air reservoirs. The specified setpoint value is either a fixedly adjustable variable, or it is specified for an adaptive operation by a control unit.

(42) The oscillation frequency of the tower is detected by an acceleration sensor. The signal is relayed to a computing unit. The air pressure of the system required to achieve the respective frequencies is calculated in a previously determined frequency-pressure curve of the system. The resulting signal is relayed to the pressure-regulating valve as a setpoint value.

(43) FIG. 1(d)(d1) shows a further embodiment of the invention. Instead of the air spring unit (7.1) designed as an arrangement of elastic bellows (7.1.1), a roller bellows (7.1.2) is now used, which has the advantage that its cross-section does not change significantly during operation. Otherwise, all other features and functions correspond to those of FIG. 1(c)(c1).

(44) FIG. 1(e) shows a further embodiment of the invention, viz., a pneumatic cylinder (7.2) as a component of a lower pendulum rod (5) of the pendulum-tuned mass damper according to the invention. The upper pendulum rod (4) with the oscillation mass (1) is not shown. The pendulum rod (5) has an upper joint (5.2) which is designed as a ball joint. The joint is at the same time the lower joint (4.3) of the upper pendulum rod (4). The pneumatic cylinder (7.2) comprises a piston (7.2.3) which divides the cylinder space into an upper cylinder chamber (7.2.1) and a lower cylinder chamber (7.2.2). The piston (7.2.3) is moved by piston rod (7.2.4). The vertical movement of the piston takes place by means of the pressure-controlled gas/air volume (7.6). Since the cylinder space is too small, an air/gas container (7.5) outside the component is required, to ensure the functionality of the pneumatic cylinder in the sense of a selective and accurate frequency adaptation. Depending upon the requirement, the gas volume in the container (7.5) is fed into either the lower or the upper chamber of the cylinder under pressure. Corresponding valves (7.13)(7.16) and feed and discharge lines (7.10) (7.14) (7.15) (7.17) (7.18) are provided and, here as well, a regulating and control unit (7.11)(7.12) for the gas/air volume (7.6).

(45) During operation, the piston rod (7.2.4) is pushed vertically upwards or downwards by the corresponding gas pressure, as a result of which the oscillation mass (1) on the pendulum rod (4) is relieved or loaded via the ball joint (5.2). Generally, the pneumatic cylinder (7.2) can work in the pull direction and in the push direction. The chamber 7.2.2 is loaded for push, and the chamber 7.2.1 is loaded for pull.

(46) FIGS. 2(a-c) show, from various perspectives, the embodiment of the tuned mass damper according to the invention with an air spring unit (7.1) of FIG. 1 integrated into the carrier structure (6). In contrast thereto, the joint (4.2) of the pendulum rod (4) is a simple ball joint without damping units (3). For this purpose, the latter are installed in duplicate and at a 90? angle to one another between the mass (1) and the carrier structure (6). Rotational dampers are again provided as damping units here, but linear dampers based upon magnets, hydraulic dampers, or other dampers according to the prior art can also be used.

(47) FIGS. 3(a-c) show three different views of another embodiment of the damper according to the invention, viz., a transverse pendulum damper. The mass (1) is here suspended on three pendulum rods (4). Each pendulum rod (4) has an upper (4.2) and a lower joint (4.3)preferably a ball joint (4.3). The pendulum rods are connected by means of the upper joints to the carrier structure (6) and by means of the lower joints to the mass (1) in such a way that the mass can move exclusively horizontally during oscillation. The damping elements (3) are mounted here between the mass (1) and the carrier structure (6) and, in the specific example, are again designed as rotational dampers, but can also be other dampers of the prior art. For a circumferentially uniform damping, two damping elements (3) are sufficient in this embodiment, with three pendulum rods (4) and six joints (4.2)(4.3) in the upper suspension. However, three and more such dampers can also be used.

(48) FIGS. 4(a-d) show four different views of another embodiment of the transverse damper according to FIG. 3. In the case of the transverse pendulum, the support device (7) conceived as a supporting spring or air spring unit does not necessarily, or at least desirably, have to act at the center of gravity of the mass or in close proximity thereto. It is thus possible to allow it to act above the mass and thus to pass it through the mass; this results in a lower height of the component, which in turn reduces the required installation space.

(49) FIG. 4(a) shows how the supporting spring unit (7) is guided through an opening of the mass (1). The upper joint (5.2) of the pendulum rod (5), which is identical here to the support device (7), is now arranged above the oscillation mass (1) and attached to a holder (6.1), which in turn is connected to the mass. The opening in the mass is designed such that it allows sufficient free space for the movement of the lower pendulum (5) or the supporting spring unit (7). In this embodiment as well, it can be seen that the upper pendulum rods (4) have a significantly smaller length (4.1) in comparison to the length (5.1) of the lower pendulum rod (5).

(50) FIG. 4(b) shows a side view of the tuned mass damper according to the invention according to FIG. 4(a). In addition, a rotational damper unit (3) with three rotary disks can also be seen, which is attached to the mass and is effective in the case of oscillating movement thereof.

(51) FIG. 4(c) shows a sectional view of a tuned mass damper according to FIG. 4(a).

(52) FIG. 4(d) shows a perspectival view of the component according to FIG. 4(c).

(53) In FIGS. 2-4, the support device (7) in each case comprises an air spring element (7.1) according to the invention. However, it is provided that the same embodiments as shown and described be used, but with a pneumatic cylinder (7.2) according to FIG. 1(e).

(54) FIG. 5 shows a pendulum-tuned mass damper according to the invention with a pneumatic cylinder (7.2) as the core piece of the support device (7). In contrast to FIG. 1(e), which shows only the second (lower) pendulum rod (5) with the pneumatic cylinder (7.2), the second pendulum rod (5) in this embodiment with a corresponding pneumatic cylinder (7.2) is provided as an upper pendulum rod (5), and the first pendulum rod (4) with the oscillation mass (1) is provided as a lower pendulum rod (4). A ball or Cardan joint (4.2) with a rotational damping element (3) is correspondingly arranged at the lower end of the carrier structure (6), while a freely-movable joint (5.3) now closes the support device upwards and is connected there to the carrier structure. The shape and arrangement of the oscillation mass (1) on the pendulum rod (4) in relation to the arrangement of the pendulum rod (5) corresponds approximately to the corresponding part of FIG. 4.

(55) FIG. 6 in principle shows the same arrangement of a pendulum-tuned mass damper according to the invention according to FIG. 5, but the pneumatic cylinder (7.2) is here replaced by an air spring unit (7.1)in particular, a roller bellows (7.1.2). The latter transmits the force, via the components (7.1.3) movable relative to one another, to the mass (1) on the lower first pendulum rod (4).