Abstract
The invention relates to a tuned mass damper or vibration damper which, with the aid of an assembly (2) of a plurality of stacked, specially shaped or bent leaf springs (2.1), can be adapted over a certain range to the disturbance frequencies acting on a component to be damped or of the vibration system to be damped, the position of the damper mass (1, 34) being changed essentially only slightly. The invention relates in particular to one- and two-dimensionally effective tuned mass dampers. The tuned mass dampers according to the invention are suitable in particular for installations, vehicles and machines that undergo frequent changes in rotational speed, resulting frequently in disturbance frequencies that become noticeable, in particular, in the form of structure-borne sound, or other vibrations.
Claims
1. A one- or two-dimensionally effective tuned mass damper for a vibration system, which can be adapted to disturbance frequencies, comprising a machine, a vehicle, or an installation, which is exposed to said disturbance frequencies to be damped, essentially comprising (i) a damper mass, (ii) at least one leaf-spring assembly capable of vibrating in case of force flows, which assembly is firmly connected directly or indirectly to a support unit of said machine or installation and directly or indirectly to the damper mass and has a predetermined stiffness, and (iii) a device for changing the predetermined stiffness of the leaf-spring assembly and thus for adjusting the frequency of the vibration system to the disturbance frequencies, the device being connected both to the leaf-spring assembly as well as to the support device of the vibration system, wherein (iv) the at least one leaf-spring assembly has one or more leaf-springs stacked in parallel, which are pre-bent about their transverse axis in a force-free state, the longitudinal axis of the leaf-springs or the leaf-spring assembly being defined by the direction of the force applied during operation, (v) the two end or clamping regions of the individual leaf-springs or the leaf-spring assembly are deflected or offset relative to one another by a defined, preset amount with respect to their position in relation to the longitudinal axis, said predetermined deflection corresponding to a specific stiffness of the leaf-spring assembly and thus to a specific frequency of the vibration system connected to the leaf-spring assembly, and (vi) the device comprises a displacement device, a rotary device, a piezo element, or a bimetallic element, the device or element being designed and arranged such that it allows a reversible bending of the pre-bent leaf-spring assembly in the direction perpendicular to the longitudinal axis, and thus, depending on the direction of displacement or rotation by the device, an increase or decrease in the preset deflection of the pre-bent leaf-spring assembly is achieved, whereby the predetermined stiffness of the leaf-spring assembly can be changed along its longitudinal axis and the frequency of the vibration system can thus be adapted to a changed disturbance frequency.
2. The adaptive tuned mass damper according to claim 1, wherein the leaf-spring assembly or the leaf-springs formed from it are in an S-shape.
3. The adaptive tuned mass damper according to claim 2, wherein the leaf-spring assembly or the leaf-springs are bent symmetrically in an S-shape in the central region.
4. The adaptive tuned mass damper according to claim 1, wherein the two end or clamping regions of the individual leaf-springs or the leaf-spring assembly are arranged parallel to one another.
5. The adaptive tuned mass damper of claim 1, wherein the leaf-spring assembly has at least two leaf-springs.
6. The adaptive tuned mass damper of according to claim 1, wherein the stacked leaf-springs of the leaf-spring assembly have a distance from one another of <2 mm or lie directly on top of one another, as a result of which the vibration system experiences additional friction damping.
7. The adaptive tuned mass damper according to claim 6, wherein the stacked leaf-springs of the leaf-spring assembly are separated from one another by elastic layers having a thickness of >0 and <2 mm.
8. The adaptive tuned mass damper according to claim 1, wherein the leaf-spring assembly in the force-free state has a deflection of 15-30% of the free spring length in the direction of the longitudinal axis or in the load direction.
9. The adaptive tuned mass damper according to claim 8, wherein the free spring length is 50-500 mm.
10. The adaptive tuned mass damper according to claim 1, wherein the leaf-springs of the leaf-spring assembly have a round or oval bore in the central region for influencing the spring dynamic natural frequency.
11. The adaptive one-dimensionally effective tuned mass damper according to claim 1, wherein the damper mass is composed of one or more plates packed together and is laterally delimited at opposite points by at least two parallel leaf-spring assemblies, which is firmly connected through their first end or clamping region with the damper mass and through their second end or clamping region to the support unit respectively, the damper mass being able to vibrate in a direction which corresponds to the longitudinal axis or loading direction of the leaf-spring assemblies.
12. The adaptive tuned mass damper according to claim 11, wherein the device for changing the predetermined stiffness of the leaf-spring assembly is a mechanical, hydraulic, pneumatic, or electrical displacement device which is arranged on the support unit above or below the damper mass and the leaf-spring assemblies.
13. The adaptive tuned mass damper according to claim 12, wherein the damper mass is guided and held parallel to the displacement direction by guide springs during its movement in the displacement direction caused by the changed deflection of the leaf-spring assemblies.
14. The adaptive, two-dimensionally effective tuned mass damper according to claim 1, wherein the damper mass is arranged in a ring around the concentrically mounted support unit in such a way that it is able to vibrate in a plane radially to the support unit, and is connected therewith through three to eight leaf-spring assemblies which are arranged in a star shape and at a selected same or different distance angle from one another within the mass ring and are connected to the mass via their first end or clamping region and to said concentrically mounted support unit via their second end or clamping region.
15. The adaptive tuned mass damper according to claim 14, wherein the device for changing the predetermined stiffness of the leaf-spring assemblies comprises a mechanically, hydraulically, pneumatically, or electrically operated, concentrically mounted rotating device, with the aid of which a rotating of the concentric damper mass relative to the concentrically mounted support unit can be carried out, so that a change in the predetermined deflection of all radially arranged leaf-spring assemblies is achieved.
16. An adaptive torsionally effective tuned mass damper according to claim 1, wherein the damper mass is arranged in a ring around the concentrically mounted support unit of the machine, which executes circular vibrations when excited, and the ring-shaped damper mass consists of at least two or three segments of a circle, which are connected by a corresponding number of leaf-spring assemblies, said leaf-spring assemblies being arranged tangentially with respect to their longitudinal axis in such a way that they have a dampening effect in the event of rotational vibrations of the support unit or the machine.
17. The adaptive tuned mass damper according to claim 1, wherein when force is applied, the ratio of the vibration travel of the damper mass to the initiated vibration travel of the vibration system to be damped is >100-400 in the undamped state.
18. The adaptive tuned mass damper according to claim 1, wherein with further deflection of the leaf-spring assembly by 30% of the original deflection in the direction which increases the stiffness of the leaf-spring assembly under load, a double to threefold increase in frequency is achieved.
19. The adaptive tuned mass damper according to claim 1, wherein with further deflection of the pre-bent leaf-spring assembly by 30% of the original deflection in the direction which reduces the stiffness of the leaf-spring assembly under load, the frequency is reduced by 20-50%.
20. The adaptive tuned mass damper according to claim 1, wherein it has one or more additional damping elements.
21. A use of a tuned mass damper according to claim 1, to reduce or eliminate disturbance frequencies in a machine, a vehicle, or an installation, which are caused by rotating components of a transmission, generator, a drive train or of rotor blades or rotor hubs.
22. A wind power plant comprising a tuned mass damper according to claim 1.
Description
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0035] FIG. 1 (a), (b) shows two different perspective views of an inventive, one-dimensional effective tuned mass damper. The damper mass (1) consists of several interconnected rectangular plates, the number and mass of which can be selected according to requirements. The package of mass plates (1) is delimited on the two lateral surfaces by two leaf-spring assemblies (2) which are composed of several leaf-springs (2.1) stacked on top of one another, in this case five of them. The leaf-springs are pre-bent centrally and in the same direction in an S-shape, with their two (upper and lower) end or clamping regions being aligned parallel but offset to one another. In this embodiment, the individual leaf-springs are separated from one another by a small distance/gap (<2 mm). Each of the two leaf-spring assemblies is arranged in such a way that the upper end region (2.1.1) of the arrangement is attached to the side of the damper mass plates (1), while the lower end or clamping region (2.1.1) is firmly connected to the support unit (11) of the vibration system (system, machine, etc.). The support unit (11) has two fastening surfaces (10) for the vibration system to be damped. FIG. 1 (a) also shows an upper guide spring (3) which is firmly connected at one position to the package of mass plates (1) and which causes the mass plates, which vibrate in the vertical direction (9) during operation, to prevent jamming or breaking due to a force. The guide spring (3) is connected to a lower guide spring (4) via a support plate (7) (not shown here), which is attached to the underside of the damper mass (1) and has the same task as the upper guide spring (3). FIG. 2 (a) shows the view from above of the tuned mass damper according to the invention, as described in FIG. 1. The guide spring plate (3) is held by two guide spring support plates (7) so that the mass unit (1) cannot move in the transverse direction (13, vertical double arrow) when force is applied. The direction (8) is also shown, in which the damper mass moves when the displacement device is moved (5)(6) (not shown) by bending the leaf-spring assemblies (2). FIG. 2 (b) shows a side view of the tuned mass damper according to the invention from FIG. 1. In this case the two leaf-spring assemblies are arranged on the outside, and are bent in an S-shape and consist of several individual leaf-springs that are separate from one another. In its upper end it has the attachment with the damper mass (1). In the lower end region, the spring assemblies are firmly connected to the support device (11). A displacement device is mounted on the support device and can be displaced in the direction (8) along the transverse connection of the support device. In the embodiment shown, this displacement device is equipped with a drive system (6): These are: (6.1): drive motor, (6.2): displacement spindle, (6.3): spindle nut. The displacement device can be operated manually, pneumatically, hydraulically or pneumatically. The displacement unit (5), which can be slid back and forth along the direction (8), is connected to the support device (1) of the guide springs (3)(4) on the left-hand side. When the device (5) is moved to the right (8), the damper mass (1) is also moved to the right, as a result of which the leaf-spring assemblies (2) on both sides are bent further up compared to their original bending or are deflected further in the direction (8) (enlargement of the original “S-shape”). This reduces their stiffness in relation to the perpendicularly (9) effective vibration forces, which results in a drop in the frequency of the system. Consequently, when shifted to the left, the original deflection of the leaf-springs is reduced (reduction of the “S-shape”), which leads to increased stiffness and a higher frequency.
[0036] FIG. 3 (a) (b) shows details of a single leaf-spring (2.1) according to the invention, which is preferably used as a package of several such leaf-springs in the tuned mass damper according to the invention. FIG. 3(a) represents the side view of such a spring in a force-free state (continuous line). (2.1.1) represents the end region to which the spring is clamped or fastened. The marked dimension (2.1.2) represents the original pre-bent deflection of the spring, corresponding to the form of the S-shape of the spring. The dimension 2.1.6 indicates the direction of the additional or reduced deflection of the spring when the mass is displaced in the direction (2.1.6) compared to the initial deflection (2.1.2). The corresponding springs are drawn accordingly (dash-dot lines). With a swinging mass (1), the leaf-springs are resiliently bent in the load direction (2.1.3). Furthermore, the free spring length (2.1.5) is shown for the three spring states. FIG. 3(b) shows several perspective views of the leaf-spring of FIG. 3(a) for clarity. In a special further embodiment, such a leaf-spring or leaf-spring assembly has a central recess (2.1.4). which can be useful for the dynamic natural frequency change of the spring.
[0037] FIGS. 4, 5 and 6 show an embodiment of the damper according to the invention, which is two-dimensional, i.e. effective in a selected plane. FIG. 4(a) shows a perspective view of such an embodiment. FIG. 4(b) shows the view from above and below, respectively, and FIG. 4(c) shows the view in a side view. (1) represents the damper mass, which preferably has a ring shape and is rotatably mounted about an imaginary axis in the center of the circular shape formed by the mass perpendicular to the plane of the ring. However, any other geometric shape can also be chosen, such as a triangle, square, rectangle or any polygon. It is essential that there is free space for the leaf-springs within the mass body 1. The support unit (11) with connection surfaces (10) for the vibration system is also arranged concentrically. The mass ring is connected to said concentrically mounted support unit (11) via several, in the shown case six pre-bent S-shaped leaf-spring assemblies (2), in this specific case evenly distributed and arranged in a star shape, (the leaf-spring assemblies can also be unevenly distributed, if different frequencies should be damped in different directions). One end or clamping region (2.1.1) of the leaf-spring assembly is connected to the mass ring (1), and the second end or clamping region is connected to the support unit. The support unit can be rotated in relation to the mass ring via rotatable adjusting levers and a drive (6), as a result of which all existing leaf-spring assemblies (2) bend to a greater or lesser extent, depending on the direction of rotation, compared to their initial bending. The stiffness of the damper can thus be easily adjusted and adapted to the disturbance frequencies of the vibration system. FIG. 5 (a) (b) shows details of the rotating unit (14-18) in the center of the damper. (14) represents an adjusting lever, (15) a torsion lever, (16) the pivot bearing, (17) a torque tube, and (18) a torsion bar. In order to enable the required freedom of movement of the mass (1), the sequential connection of the torsion tube (17) with the torsion bar (18) is provided. Together these form an easily bendable torsion bar. In order to achieve the lowest possible radial stiffness influence of the pivot bearing on the overall system, even at low frequencies, it is also possible to arrange several tubes in a meandering configuration. FIG. 6 shows the same embodiment as in FIGS. 4 and 5. (2.1) represents the leaf-spring assemblies before the start of the adjustment, while (2.1.a) shows the same leaf-spring assembly after rotation relative to the concentrically mounted support unit in the indicated direction of the arrow (19), which leads to greater bending (deflection) of the individual leaf-spring assemblies and thus to a reduced stiffness and consequently a shift towards low frequencies.
[0038] FIG. 7 shows a typical characteristic curve (frequency change of the vibration system with respect to axial displacement of the leaf-spring) of three leaf-spring assemblies with different initial stiffness. The initial stiffness is generally determined, among other things, by the number of individual springs, the thickness of the individual springs, the free spring length and the original pre-bending in the S-shape. The central solid line represents the characteristic curve of a leaf-spring assembly with a specific stiffness. The upper dashed characteristic curve depicts the curve for a leaf-spring assembly with comparatively higher stiffness, while the lower dashed characteristic curve represents the corresponding relationship for a comparatively soft spring arrangement. The X-axis value indicates the percent of positive or negative displacement or rotation versus the force-free pre-bent spring (0%). It can be seen that with a positive shift (0 to +50%) the leaf-spring orientation becomes steeper, which leads to a significant increase in frequency. A negative shift (0 to −50%) leads to a flatter leaf-spring alignment and thus to a lower frequency. It can be seen from all three curves that with an additional deflection/bending of the springs, the frequency of the absorber system decreases and increases with a reduction in the deflection/bending. Here, when the reduced deflection is +20% compared to the original deflection, the frequency increases by about 100% compared to the original frequency. With +30% relative reduced deflection/bending, a frequency increase of 150-200% is already achieved, and with an additional reduction in deflection of +40% compared to the initial deflection, the frequency change already increases by up to 400%. If, on the other hand, the original deflection/bending is increased compared to the initial value (negative values on the X-axis) by corresponding displacement or rotation then reduces the stiffness of the leaf-springs, which leads to a lowering of the frequency. With a 20% increase (−20%) of the deflection, the frequency decreases by about 20%, with a 30% increase in the deflection (−30%), the frequency decreases by about 40%, and with a 40% increase in the deflection (−40%) by about 50%. Further increases in the deflection only have a very small influence on the frequency.
[0039] FIG. 8 (a) (b) shows an embodiment of the tuned mass damper according to the invention with a circular or tangential arrangement of the leaf-spring assemblies. This allows rotating components to be adaptively damped. A damper mass (34) is coupled to the circularly vibrating machine or a support part of this machine via tangentially arranged packages of leaf-spring assemblies (2). In the specific case, four (but it can also be three to eight) preferably evenly distributed packages of leaf-spring assemblies (2) (comprising 20-40 individual bent leaf-springs) are attached to the damper mass. The damper mass itself comprises corresponding, preferably circular segments, which are connected to one another via the said leaf-spring assemblies. As described, the leaf-spring assemblies are equipped with the appropriate displacement devices (6) for adjusting the spring stiffness. The frequency of the system is thus adjusted by moving the spring units (2) along their direction of displacement (8) change in the curved S-shape). The damper mass segments (34) are also connected to the rotating support unit (30) or to the rotating machine itself via correspondingly arranged guide springs (31)(33).
[0040] FIG. 9 shows a wind power plant with a gear in which a circular tuned mass damper according to the invention as shown in FIG. 8 is installed (2)(5(9(6)(31)(32(34). The damper is built into the transmission in such a way that it can absorb torsional vibrations from the transmission. Instead of an annular tuned mass damper according to the invention, individual absorbers arranged in a correspondingly circular manner according to FIG. 1 or 2 can also be used. Positions (40) and (41) represent attachment points on the wind turbine. The tuned mass damper according to the invention can also be connected to the rotor hub.
[0041] FIG. 10 shows a direct drive wind turbine (without gearbox) using a circular tuned mass damper according to FIG. 8. The circular tuned mass damper according to the invention can be mounted both in the stator and in the rotor of the generator. Otherwise, the same conditions apply as for the system with gearbox as described above.
[0042] FIG. 11 shows a modified embodiment of the damper according to the invention according to FIGS. 4-6 in a perspective view. (a) shows a half-side section through the ring shape of the damper, while (b) shows the complete ring shape. In this embodiment, two stars made of leaf-springs or leaf spring packages are connected together with a ring-shaped mass (1). There is a front stack of leaf-springs (51) and a rear stack of leaf-springs (50) in the shape of a star. Both are arranged in opposite directions to each other and can be moved, so that both stars experience the same radial stiffness changes when they rotate in relation to one another. The hub (52) and the bolt (53) are turned against each other with a flanged gear drive or a lever and a force element in order to set the desired stiffness.
