Energy collection type negative stiffness damper

Abstract

The utility model provides an energy collection type negative stiffness damper. The energy collection type negative stiffness damper comprises an electromagnetic damping unit, a negative stiffness unit and an accessory device. Wherein the electromagnetic damping unit comprises a coil combination and a permanent magnet combination and is used for providing electromagnetic damping and converting damping energy into electric energy; the negative stiffness unit comprises a fixed permanent magnet pair and a movable permanent magnet pair, and negative stiffness force is formed. The accessory device comprises a supporting shell and a middle frame. Under the action of external force, the supporting shell and the middle frame can move relatively. The coil combination of the electromagnetic damping unit is connected in series and fixed to the supporting shell, the permanent magnet combination is fixed to the middle frame, electromagnetic damping force is formed through relative movement of the coil combination and the permanent magnet combination, and meanwhile damping energy conversion is conducted. The device is novel and compact in structural form, and has the characteristics of negative rigidity, electromagnetic damping and energy collection at the same time.

Description

Technical Field

[0001] The utility model relates to the technical field of structural vibration control, and more specifically, to an energy harvesting negative stiffness damper. Background Art

[0002] Structural vibration control refers to reducing or suppressing the vibration of a structure under external excitations such as wind, earthquake, mechanical vibration, etc. through various techniques and methods, so as to ensure the safety, comfort and normal functioning of the structure. This control technology is widely applied in fields such as construction engineering, bridges, aerospace, and mechanical equipment. Structural vibration control can be divided into passive control, semi-active control, and active control. Among them, active control can achieve the optimal control effect. The linear quadratic regulator is one of the classical active control algorithms, and the corresponding active control force shows a negative stiffness characteristic with respect to the deformation. Based on this characteristic, a series of negative stiffness damper types have been proposed and verified numerically or experimentally. The current negative stiffness units can be constructed by prestressed springs, buckling beams, or magnet arrangements. However, its damping part usually needs to be combined with other damping mechanisms, including magnetorheological damping and viscous damping. On the other hand, the electromagnetic damper is a new damping mechanism that can provide electromagnetic damping and energy harvesting functions. Its damping force is approximately linear with the end velocity, which is convenient for design.

[0003] The characteristics of the negative stiffness damper and the electromagnetic damper have been verified separately in previous studies. In addition, it has been found that when the negative stiffness damper is used for the vibration control of bridge stay cables, it can cause the amplification of the local position response of the damper and simultaneously reduce the global vibration response of the stay cables, which means that its negative stiffness unit has the potential to improve the energy harvesting power on the premise of ensuring the global vibration control effect. However, currently, no literature has attempted to integrate negative stiffness, electromagnetic damping, and energy harvesting functions into a single damper. The energy harvesting negative stiffness damper of the utility model integrates a magnet-based negative stiffness unit and an electromagnetic damping unit into one body, with a compact and novel structural form. Compared with the traditional negative stiffness damper, the damper of the utility model provides a controllable electromagnetic damping force and can convert vibration energy into electric energy for harvesting; compared with the electromagnetic damper, the damper of the utility model combines a negative stiffness unit, can provide a negative stiffness force, and has the potential advantage of improving the energy harvesting power. The device of the utility model has a compact and novel structural form and simultaneously has the characteristics of negative stiffness, electromagnetic damping, and energy harvesting. Summary of the Utility Model

[0004] Aiming at the limitations of the prior art, the utility model proposes an energy harvesting negative stiffness damper, which ingeniously integrates an electromagnetic damping unit and a negative stiffness unit in the same device. While providing negative stiffness and electromagnetic damping forces, this solution can convert damping energy into electric energy.

[0005] The above object of the present utility model is achieved by the following technical solutions: An energy harvesting negative stiffness damper, comprising an electromagnetic damping unit, a negative stiffness unit and an accessory device; wherein, the electromagnetic damping unit includes a coil assembly and a permanent magnet assembly, providing electromagnetic damping and converting damping energy into electrical energy; the negative stiffness unit includes a fixed permanent magnet pair and a moving permanent magnet pair, forming a negative stiffness force; the accessory device includes a support housing and an intermediate frame; the support housing and the intermediate frame are respectively connected to the mounting shaft; under the action of an external force, the support housing and the intermediate frame can move relative to each other; the coil assembly of the electromagnetic damping unit is fixed to the support housing, and the permanent magnet assembly is fixed to the intermediate frame, and the relative movement of the coil assembly and the permanent magnet assembly forms an electromagnetic damping force while performing damping energy conversion.

[0006] Preferably, the middle part of the intermediate frame is hollowed out, and the permanent magnet assembly is arranged at the hollowed-out position.

[0007] Preferably, the mounting shaft includes a first mounting shaft and a second mounting shaft. The first mounting shaft is connected to the support housing and moves synchronously; the second mounting shaft is connected to the intermediate frame and moves synchronously.

[0008] Preferably, the coil assembly includes a plurality of coils, arranged at the hollowed-out position of the intermediate frame; the plurality of coils are connected in series and move with the movement of the support housing.

[0009] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0010] The energy harvesting negative stiffness damper of the present utility model is applied to structural vibration control. Compared with the traditional negative stiffness damper using other damping mechanisms, the electromagnetic damping force provided by the damper of the present utility model has an explicit relationship with the connected load resistance, with high controllability, an approximate linear relationship with the relative velocity at the end, and at the same time of providing the electromagnetic damping force, part of the damping energy can be harvested, and the harvested energy can be applied to power wireless sensors or semi-active control. Compared with the traditional electromagnetic damper, the damper of the present utility model combines the suction characteristics of magnets to provide a negative stiffness force. This damper has an important application prospect in structural vibration control. Description of the Drawings

[0011] Figure 1 is a structural cross-sectional view of the energy harvesting negative stiffness damper according to an embodiment of the present utility model;

[0012] Figure 2 is a schematic arrangement diagram of the permanent magnet assembly of the electromagnetic damping unit in the energy harvesting negative stiffness damper according to an embodiment of the present utility model;

[0013] Figure 3It is a schematic diagram of the position of the coil combination of the electromagnetic damping unit in the energy harvesting negative stiffness damper according to an embodiment of the present invention;

[0014] Figure 4 It is a schematic diagram of the arrangement of the fixed permanent magnet pairs and the moving permanent magnet pairs in the negative stiffness unit of the energy harvesting negative stiffness damper according to an embodiment of the present invention;

[0015] Figure 5 It is a three-dimensional design schematic diagram of the energy harvesting negative stiffness damper according to an embodiment of the present invention;

[0016] Figure 6 It is a result diagram of the negative stiffness force calculated through numerical simulation according to an embodiment of the present invention when the connected load resistance is equal to the internal resistance of the coil combination; the abscissa of the reference diagram represents the relative displacement at the end of the damper;

[0017] Figure 7 It is a result diagram of the electromagnetic damping force calculated through numerical simulation according to an embodiment of the present invention when the connected load resistance is equal to the internal resistance of the coil combination; the abscissa of the reference diagram represents the relative displacement at the end of the damper;

[0018] Figure 8 It is a result diagram of the overall control force of the damper calculated through numerical simulation according to an embodiment of the present invention when the connected load resistance is equal to the internal resistance of the coil combination; the abscissa of the reference diagram represents the relative displacement at the end of the damper;

[0019] Figure 9 It is a result diagram of the energy harvesting power calculated through numerical simulation in an embodiment of the present invention when the connected load resistance is equal to the internal resistance of the coil combination;

[0020] In the figure, 111 - the first permanent magnet pair; 112 - the second permanent magnet pair; 113 - the third permanent magnet pair; 114 - the fourth permanent magnet pair; 115 - the fifth permanent magnet pair; 116 - the sixth permanent magnet pair; 121 - the first coil; 122 - the second coil; 123 - the third coil; 124 - the fourth coil; 211 - the first fixed permanent magnet group; 212 - the second fixed permanent magnet group; 221 - the first moving permanent magnet group; 222 - the second moving permanent magnet group; 31 - the support housing; 32 - the intermediate frame; 331 - the first mounting shaft; 332 - the second mounting shaft; 34 - the limit bolt. Detailed implementation manners

[0021] Next, the accompanying drawings in the embodiments of the present invention will be combined to clearly and completely describe a certain embodiment of the present invention. Obviously, the described embodiment is not all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0022] As Figure 1 shown, this embodiment provides an energy harvesting negative stiffness damper, which includes an electromagnetic damping unit, a negative stiffness unit and an accessory device. The entire system can provide negative stiffness force, electromagnetic damping force and energy harvesting function.

[0023] The electromagnetic damping unit includes a permanent magnet combination and a coil combination. The permanent magnet combination includes a first permanent magnet pair 111, a second permanent magnet pair 112, a third permanent magnet pair 113, a fourth permanent magnet pair 114, a fifth permanent magnet pair 115, and a sixth permanent magnet pair 116. The coil combination includes a first coil 121, a second coil 122, a third coil 123, and a fourth coil 124. Each of the first permanent magnet pair 111, the second permanent magnet pair 112, the third permanent magnet pair 113, the fourth permanent magnet pair 114, the fifth permanent magnet pair 115, and the sixth permanent magnet pair 116 includes a pair of permanent magnets arranged with the same magnetization direction. The electromagnetic damping unit provides electromagnetic damping and converts the damping energy into electrical energy.

[0024] The negative stiffness unit includes a fixed permanent magnet pair and a moving permanent magnet pair. The fixed permanent magnet pair includes a first fixed permanent magnet group 211 and a second fixed permanent magnet group 212. The moving permanent magnet pair includes a first moving permanent magnet group 221 and a second moving permanent magnet group 222. The negative stiffness unit provides a negative stiffness force.

[0025] The accessory device includes a support housing 31, an intermediate frame 32, a mounting shaft 33 and a limit bolt 34.

[0026] The mounting shaft 33 includes a first mounting shaft 331 and a second mounting shaft 332. The first mounting shaft 331 is connected to the support housing 31 and moves synchronously; the second mounting shaft 332 is connected to the intermediate frame 32 and moves synchronously. The vibration of the external structure drives the movement of the first mounting shaft 331 and the second mounting shaft 332, thereby causing the relative movement between the support housing 31 and the intermediate frame 32. The relative response between the first mounting shaft 331 and the second mounting shaft 332 represents the relative response at the ends of the energy harvesting damper.

[0027] The coil combinations of the electromagnetic damping unit are connected in series and fixed in the middle of the support housing 31, and the permanent magnet combination is fixed to the intermediate frame 32. The relative movement between the coil combination and the permanent magnet combination forms an electromagnetic damping force, and at the same time, the damping energy is converted.

[0028] As Figure 2 shown, the middle of the intermediate frame 32 is hollowed out to fix the permanent magnet combination. Among them, the first permanent magnet pair 111, the second permanent magnet pair 112, and the third permanent magnet pair 113 are fixed to the upper half of the hollowed-out position in the middle of the intermediate frame 32. The fourth permanent magnet pair 114, the fifth permanent magnet pair 115, and the sixth permanent magnet pair 116 are fixed to the lower half of the hollowed-out position in the middle of the intermediate frame 32.

[0029] As Figure 3 and Figure 5 shown, the first coil 121 and the second coil 122 are fixed to the support housing 31, and their spatial positions at the equilibrium position are in the middle of the magnet pairs of the first permanent magnet pair 111, the second permanent magnet pair 112, and the third permanent magnet pair 113. The third coil 123 and the fourth coil 124 are fixed to the support housing 31, and their spatial positions at the equilibrium position are in the middle of the magnet pairs of the fourth permanent magnet pair 114, the fifth permanent magnet pair 115, and the sixth permanent magnet pair 116. The first coil 121, the second coil 122, the third coil 123, and the fourth coil 124 are connected in series.

[0030] As Figure 4 shown, the fixed permanent magnet pair of the negative stiffness unit is fixed to the end of the support housing 31, and the moving permanent magnet pair is fixed to the middle frame 32 through the limit bolt 34. Specifically, the fixed permanent magnet pair of the negative stiffness unit includes a first fixed permanent magnet group 211 and a second fixed permanent magnet group 212, which are respectively fixed to the ends of the support housing 31. The moving permanent magnet pair includes a first moving permanent magnet group 221 and a second moving permanent magnet group 222, which are respectively fixed to the ends of the middle frame 32 through the limit bolt 34. The first fixed permanent magnet group 211 and the first moving permanent magnet group 221 are located on the same side of the damper and have the same magnetization direction, forming an attractive magnetic force. The second fixed permanent magnet group 212 and the second moving permanent magnet group 222 are located on the other side of the damper and have the same magnetization direction, forming an attractive magnetic force.

[0031] The relative movement speed between the support housing 31 and the middle frame 32 is approximately equivalent to the relative movement speed between the permanent magnet combination and the coil combination; when the energy harvesting negative stiffness damper is connected to a load resistor, the electromagnetic damping force of the electromagnetic damping unit can be expressed by the following formula:

[0032] (1);

[0033] Wherein, F d represents the damping force provided by the electromagnetic damping unit, K eq represents the mechanical constant of the electromagnetic damping unit, c p represents the parasitic damping coefficient of the electromagnetic damping unit, R coil represents the internal resistance of the electromagnetic damping unit, that is, the internal resistance of the coil combination, R load represents the load resistor connected to the damper, vIt represents the relative movement speed of the coil combination and the permanent magnet combination, that is, the relative speed at the end of the energy harvesting negative stiffness damper. It should be understood that an equivalent resistance circuit and a load electrical appliance can replace the load resistor to achieve a similar damping force effect. Therefore, the scope of the utility model patent cannot be limited by this.

[0034] The electromagnetic damping unit can achieve the energy conversion function, and the voltage generated by it can be expressed by the following formula:

[0035] ;

[0036] Wherein, U represents the voltage generated by the electromagnetic damping unit. When the energy harvesting negative stiffness damper is connected to the load resistor, the energy harvesting power of the damper can be expressed by the following formula:

[0037] (3);

[0038] Wherein, P represents the energy harvesting power of the energy harvesting negative stiffness damper, η represents the energy transfer efficiency of the energy harvesting negative stiffness damper.

[0039] The negative stiffness force of the negative stiffness unit can be expressed as:

[0040] ;

[0041] Wherein, F 1 represents the magnet suction force generated by the first fixed permanent magnet group 211 and the first moving permanent magnet group 221, F 2 represents the magnet suction force generated by the second fixed permanent magnet group 212 and the second moving permanent magnet group 222. The suction force is related to the distance between the fixed permanent magnet group and the moving permanent magnet group on the same side, that is, related to the relative moving displacement x between the support housing 31 and the intermediate frame 32. k s represents the equivalent negative stiffness coefficient formed by the magnet suction forces at both ends.

[0042] The utility model is verified by numerical simulation. Among them, the permanent magnet sizes of the first permanent magnet pair 111, the second permanent magnet pair 112, the third permanent magnet pair 113, the fourth permanent magnet pair 114, the fifth permanent magnet pair 115, and the sixth permanent magnet pair 116 in the permanent magnet combination of the electromagnetic damping unit are all 12.5 × 70 × 50 mm, and rectangular neodymium iron boron permanent magnets are used. The permanent magnet sizes of the fixed permanent magnet pair and the moving permanent magnet pair of the negative stiffness unit are both 20 × 89 × 50 mm, and rectangular neodymium boron iron permanent magnets are used. The first coil 121, the second coil 122, the third coil 123, and the fourth coil 124 in the coil combination are connected in series, with a diameter of 0.8 mm and 153 turns. The internal resistance of the coil combination is 5 ohms. A motion with a frequency of 2 Hz and an amplitude of 20 mm is applied to the damping end, that is, the first mounting shaft 331 and the second mounting shaft 332.

[0043] Figure 6 It shows the negative stiffness force output in the numerical simulation when the externally connected load resistance is equal to the internal resistance of the coil combination. The abscissa is the relative displacement between the support housing 31 and the intermediate frame 32, that is, the relative displacement of the end of the energy harvesting negative stiffness damper, and the ordinate is the stiffness force. It can be seen from the figure that the stiffness force shows a negative slope with the relative displacement of the damper end, representing the negative stiffness characteristic.

[0044] Figure 7 It shows the damping force output in the numerical simulation when the externally connected load resistance is equal to the internal resistance of the coil combination. The abscissa is the relative displacement between the support housing 31 and the intermediate frame 32, that is, the relative displacement of the end of the energy harvesting negative stiffness damper, and the ordinate is the electromagnetic damping force. It can be seen from the figure that the electromagnetic damping unit in the damper presents an electromagnetic damping force.

[0045] Figure 8 It shows the overall control force of the damper output in the numerical simulation when the externally connected load resistance is equal to the internal resistance of the coil combination. It can be seen from the figure that the damper can present both negative stiffness force and electromagnetic damping force at the same time.

[0046] Figure 9 It shows the power diagram of the externally connected resistor in the numerical simulation when the externally connected load resistance is equal to the internal resistance of the coil combination. The abscissa is the relative displacement between the support housing 31 and the intermediate frame 32, that is, the relative displacement of the end of the energy harvesting negative stiffness damper, and the ordinate is the power of the externally connected resistor. It can be seen from the figure that the damper has an energy harvesting function.

[0047] In summary, the present utility model realizes the simultaneous negative stiffness force, electromagnetic damping force and energy harvesting function by orderly combining a magnet combination and a coil combination, with a compact and novel structural form. Existing negative stiffness dampers usually rely on additional damping mechanisms and do not have an energy harvesting function. The energy harvesting negative stiffness damper of the present utility model integrates an electromagnetic damping unit and a magnetic negative stiffness unit into one, with a simple and compact structure; its damping characteristics show a linear relationship with the deformation speed of the external structure, which is convenient for users to design; it can convert vibration energy into electrical energy, has an energy harvesting function, and can be applied to power wireless sensors or other electrical devices; its negative stiffness characteristics and deformation relationship are also simple and clear. This integrated energy harvesting negative stiffness damper has a broader application prospect.

[0048] It should be understood that the specific values involved in the above test results only represent a preferred embodiment. When the geometric parameters, quantity, model and arrangement of the permanent magnet combination, the diameter, number of turns and arrangement of the coil combination, the geometric parameters, quantity, model and arrangement of the fixed permanent magnet pair and the moving permanent magnet pair, and the dimensions of the support housing and the intermediate frame are changed, the control force and energy harvesting performance of the energy harvesting negative stiffness damper will change. Therefore, the scope of the patent of the present utility model cannot be limited by this. It should be understood that the layout of the permanent magnets and coil combinations of the electromagnetic damping unit inside the damper, the dimensions and forms of the mounting shafts, etc. depend on the requirements of the actual application conditions and cannot be used to limit the patent scope of the present utility model. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present utility model still fall within the scope covered by the utility model.

Claims

1. An energy-harvesting negative stiffness damper, characterized in that: It includes an electromagnetic damping unit, a negative stiffness unit and an auxiliary device; wherein the electromagnetic damping unit includes a coil combination and a permanent magnet combination, provides electromagnetic damping, and converts damping energy into electrical energy; the negative stiffness unit includes a fixed permanent magnet pair and a movable permanent magnet pair, forming a negative stiffness force; the auxiliary device includes a supporting shell and an intermediate frame; the supporting shell and the intermediate frame are respectively connected to the mounting shaft, and under the action of external force, the supporting shell and the intermediate frame can move relative to each other; the coil combination of the electromagnetic damping unit is fixed to the supporting shell, and the permanent magnet combination is fixed to the intermediate frame, and the relative movement of the coil combination and the permanent magnet combination forms an electromagnetic damping force, and simultaneously performs damping energy conversion.

2. An energy-harvesting negative stiffness damper according to claim 1, characterized in that: The permanent magnet combination of the electromagnetic damping unit includes a plurality of pairs of permanent magnets, each pair of permanent magnets has the same magnetization direction; the magnetic poles of adjacent pairs of permanent magnets are arranged alternately along the central axis direction of the supporting shell.

3. An energy-harvesting negative stiffness damper according to claim 1, characterized in that: The fixed permanent magnet pair of the negative stiffness unit is fixed to the end of the supporting shell, and the movable permanent magnet pair is fixed to the middle frame; the movable permanent magnet and the fixed permanent magnet arranged on the same side have the same magnetization direction to form a negative stiffness suction force.

4. An energy-harvesting negative stiffness damper according to claim 1, characterized in that: The middle portion of the intermediate frame is hollowed out, and the permanent magnet assembly is arranged at the hollowed-out position.

5. An energy-harvesting negative stiffness damper according to claim 4, characterized in that: The coil assembly comprises a plurality of coils arranged at the hollowed-out positions of the middle frame; the plurality of coils are connected in series and move along with the movement of the supporting shell.

6. An energy-harvesting negative stiffness damper according to claim 1, characterized in that: The installation shaft includes a first installation shaft and a second installation shaft; the first installation shaft is connected to the support shell and moves synchronously; the second installation shaft is connected to the middle frame and moves synchronously.

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