Dynamic prestress controllable magnetostriction active variable stiffness shock absorber and method

Abstract

The invention relates to a magnetostriction active variable stiffness shock absorber with controllable dynamic prestress and a method, in the shock absorber, a cylindrical shell is fixedly connected with a top cover and a base; an output rod is connected with a top cover through a disc spring, and the lower end of the output rod is fixedly connected with the top end of a rhombic pre-pressing mechanism. A permanent magnet and a giant magnetostrictive material rod are arranged in an inner cavity of the rhombic pre-pressing mechanism, and an exciting coil and a coil framework surround the outer sides of the permanent magnet and the giant magnetostrictive material rod; the bottom of the rhombic pre-pressing mechanism is fixedly connected with a force sensor through a threaded rod, and the force sensor monitors changes of external exciting force borne by the shock absorber in real time. The magnetic field intensity applied to the interior of the giant magnetostrictive material rod is changed by adjusting the current of the excitation coil, so that the elastic modulus of the magnetostrictive material is changed, the material rigidity and damping of the giant magnetostrictive material rod are changed, the overall structural rigidity and damping of the shock absorber are further changed, and the change of the resonant frequency of the shock absorber is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration control of precision mechanical equipment, and in particular to a magnetostrictive active variable stiffness vibration absorber with controllable dynamic prestress and a control method thereof. Background Art

[0002] When a vibration system is subjected to external forces, it will produce a vibration response, and the system stiffness will affect the natural frequency and mode shape of the structure. Variable stiffness vibration control adjusts the system's natural frequency by changing the structural stiffness, keeping it away from the external excitation frequency and avoiding resonance. It is widely used in aerospace, precision machining and other fields. In variable stiffness vibration control technology, semi-active variable stiffness control has limited adjustment capabilities and cannot fully achieve arbitrary stiffness changes. Passive variable stiffness control lacks adaptability and has difficulty coping with complex and changing vibration environments. Active variable stiffness control uses external energy and control systems to drive actuators to change structural stiffness based on the structural response and external excitation information monitored by sensors, effectively suppressing vibrations of different frequencies. However, traditional active variable stiffness control systems rely on external energy and complex control systems, are complex in structure, and are costly. Their reliability is affected by system stability and sensor accuracy. Summary of the Invention

[0003] In order to overcome the problems existing in the prior art, the purpose of the present invention is to provide a magnetostrictive active variable stiffness vibration damper and method with dynamic prestress controllable, which has dynamically adjustable stiffness, simple structure, and easy installation, can effectively reduce the harm of resonance to equipment, and can be conveniently applied to the field of vibration reduction control of precision mechanical equipment.

[0004] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0005] A dynamic prestressed and controllable magnetostrictive active variable stiffness vibration damper, comprising a top cover 1, a cylindrical shell 2, a diamond-shaped preloading mechanism 3, an output rod 4, a disc spring 5, an excitation coil 6, a coil skeleton 7, a giant magnetostrictive material rod 8, a permanent magnet 9, a force sensor 11 and a base 12; wherein the top end of the cylindrical shell 2 is fixedly connected to the top cover 1 by a thread, and the bottom end of the cylindrical shell 2 is fixedly connected to the base 12 by a bolt; a notch is left on the side wall of the cylindrical shell 2, and a cut is left at the bottom of the cylindrical shell 2 for connecting the lead wire of the force sensor 11; the threaded rod at the top of the output rod 4 passes through the through hole in the center of the top cover 1, the output rod 4 is connected to the top cover 1 by the disc spring 5, and the bottom end of the output rod 4 is fixedly connected to the base 12 by a bolt; The top of the diamond preloading mechanism 3 is fixedly connected to the threaded hole at the top of the diamond preloading mechanism 3 by a thread; arched beams are symmetrically arranged on both sides of the diamond preloading mechanism 3; a plurality of giant magnetostrictive material rods 8 and permanent magnets 9 are installed in sequence from top to bottom in the inner cavity of the diamond preloading mechanism 3 by interference fit, wherein the arched beams symmetrically arranged on both sides of the diamond preloading mechanism 3 are in contact with the permanent magnets 9; a coil skeleton 7 is installed on the outside of the giant magnetostrictive material rods 8 and the permanent magnet 9; an excitation coil 6 is wound around each coil skeleton 7; the bottom of the diamond preloading mechanism 3 is fixedly connected to the threaded hole in the center of the force sensor 11 by a threaded rod 10; the force sensor 11 is fixed to the bottom of the inner cavity of the cylindrical shell 2 through the bottom cover 12.

[0006] A groove is provided at the bottom of the top permanent magnet, a groove is provided at the top of the bottom permanent magnet, and grooves are provided at both the top and bottom of the middle permanent magnet. The top and bottom of the giant magnetostrictive material rod 8 fit into the grooves at the top and / or bottom of the permanent magnet 9, so that the magnetic flux passing through the interior of the magnetostrictive material rod 8 is reduced in leakage and diffusion.

[0007] The permanent magnets 9 are made of neodymium iron boron (NdFeB) and are magnetized from bottom to top, with an N pole at the top and an S pole at the bottom. Magnetic flux flows from the N pole of the top permanent magnet into the diamond-shaped preloading mechanism 3, then along the flexible beams on either side of the mechanism and back to the S pole of the bottom permanent magnet. This closed magnetic circuit, combined with the preloading mechanism, improves space utilization and reduces structural complexity.

[0008] The diamond-shaped pre-stressing mechanism 3 is made of a magnetic conductive material with a high elastic modulus, which provides high structural rigidity and realizes magnetic circuit closure.

[0009] The magnetic conductive material with high elastic modulus is made of spring steel, silicon steel or alloy structural steel.

[0010] The top cover 1, cylindrical shell 3, output rod 4, disc spring 5 and base 12 are made of non-magnetic conductive materials.

[0011] There are three giant magnetostrictive material rods 8, namely, a first giant magnetostrictive material rod 8-1, a second giant magnetostrictive material rod 8-2, and a third giant magnetostrictive material rod 8-3; there are four permanent magnets 9, namely, a first permanent magnet 9-1, a second permanent magnet 9-2, a third permanent magnet 9-3, and a fourth permanent magnet 9-4; there are three coil skeletons 7, namely, a first coil skeleton 7-1, a second coil skeleton 7-2, and a third coil skeleton 7-3, and the corresponding number of excitation coils 6 is also three, namely, a first excitation coil 6-1, a second excitation coil 6-2, and a third excitation coil 6-3. The present invention adopts a segmented structure, dividing the coil 6, giant magnetostrictive material rod 8, and permanent magnet 9 into multiple sections. This improves the uniformity of the magnetic field inside the giant magnetostrictive material rod 8 while ensuring the rigidity of the structure. By changing the excitation current of the coils 6-1 and 6-3, the bias magnetic field strength of the giant magnetostrictive material rods 8-1 and 8-3 can be flexibly controlled, thereby facilitating the adjustment of the prestress applied to the ends of the giant magnetostrictive material rod 8-2.

[0012] The control method of the dynamic prestressed controllable magnetostrictive active variable stiffness shock absorber is as follows: the output rod 4 is connected to the external device; when the external device is vibrated to generate an excitation force, the excitation force is transmitted along the output rod 4 of the shock absorber, passes through the diamond preloading mechanism 3, the giant magnetostrictive material rod 8, and the permanent magnet 9, and is transmitted to the force sensor 11; the force sensor 11 sends the external excitation force signal monitored in real time to the controller, and the controller calculates and outputs two sets of drive currents, one of which is output to the excitation coils at both ends to adjust the internal magnetic field state of the giant magnetostrictive material rods at both ends, so that the output forces generated by the giant magnetostrictive material rods at both ends respectively affect the giant magnetostrictive material rod in the middle. The magnetostrictive material rod forms a prestress; the current intensity is changed to dynamically adjust the prestress of the giant magnetostrictive material rod in the middle; another set of driving currents is output to the middle excitation coil; by adjusting the current of the middle excitation coil, the magnetic field intensity in the middle giant magnetostrictive material rod is changed, so that the elastic modulus of the middle giant magnetostrictive material rod is changed, thereby changing the material stiffness and damping of the middle giant magnetostrictive material rod, further changing the overall structural stiffness and damping of the shock absorber, and realizing the change of the shock absorber resonant frequency, so that the overall system composed of the external device and the shock absorber avoids the excitation frequency of the external vibration source, reducing the risk of resonance of the overall system.

[0013] Compared with existing technologies, this invention offers the following advantages: Based on the magnetostrictive effect, it dynamically adjusts the prestress of the magnetostrictive material rod, enabling a wide range of dynamic adjustment of the rod's elastic modulus. This effectively suppresses vibrations of varying frequencies and improves the system's vibration resistance over a wide frequency band. The integration of the magnetic flux loop structure and the prestressing mechanism results in a more compact structure, reducing structural complexity, effectively reducing the size of the vibration damper, and improving the equipment's space utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the structure of the shock absorber of the present invention.

[0015] Figure 2 It is a cross-sectional view of the shock absorber structure of the present invention.

[0016] Figure 3 Schematic diagram of the giant magnetostrictive material rod structure of the present invention.

[0017] Figure 4 Schematic diagram of the magnetic flux circuit of the present invention.

[0018] Figure 5 This is a cross-sectional view of the excitation coil and skeleton structure of the present invention.

[0019] Figure 6 It is a schematic diagram of the cylindrical shell structure of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the accompanying drawings and specific implementations.

[0021] like Figure 1 and Figure 2As shown, a magnetostrictive active variable stiffness vibration damper with dynamic prestress and controllable structure according to the present invention includes a top cover 1, a cylindrical housing 2, a diamond-shaped preloading mechanism 3, an output rod 4, a disc spring 5, an excitation coil 6, a coil bobbin 7, giant magnetostrictive material rods 8 (this embodiment uses three giant magnetostrictive material rods, namely a first giant magnetostrictive material rod 8-1, a second giant magnetostrictive material rod 8-2, and a third giant magnetostrictive material rod 8-3), permanent magnets 9 (this embodiment uses four permanent magnets, namely a first permanent magnet 9-1, a second permanent magnet 9-2, a third permanent magnet 9-3, and a fourth permanent magnet 9-4) 9-1 to 9-4, a force sensor 11, and a base 12. The top end of the cylindrical housing 2 is fixedly connected to the top cover 1 by threads, and the bottom end of the cylindrical housing 2 is fixedly connected to the base 12 by bolts. A rectangular notch is provided in the side wall of the cylindrical housing 2, and a cutout is provided at the bottom of the cylindrical housing 2 for connecting leads to the force sensor 11. The threaded rod at the top of the output rod 4 passes through the through-hole in the center of the top cover 1. The output rod 4 is connected to the top cover 1 via a disc spring 5. The bottom of the output rod 4 is fixedly connected to the threaded hole at the top of the diamond-shaped preloading mechanism 3 via threads. Arched beams are symmetrically arranged on both sides of the diamond-shaped preloading mechanism 3. The inner cavity of the diamond-shaped preloading mechanism 3 is installed, from top to bottom, using an interference fit. The first permanent magnet 9-1, the first giant magnetostrictive material rod 8-1, the second permanent magnet 9-2, the second giant magnetostrictive material rod 8-2, the third permanent magnet 9-3, the third giant magnetostrictive material rod 8-3, and the fourth permanent magnet 9-4 are installed. The coil bobbins 7 (three coil bobbins in this embodiment: the first coil bobbin 7-1, the second coil bobbin 7-2, and the third coil bobbin 7-3) are wound around the first excitation coil 6-1, the second excitation coil 6-2, and the third excitation coil 6-3, respectively. The bottom of the diamond-shaped preloading mechanism 3 is fixedly connected to the threaded hole in the center of the force sensor 11 through a threaded rod 10. The force sensor 11 is fixed to the bottom of the inner cavity of the cylindrical housing 2 through a bottom cover 12.

[0022] like Figure 3 and Figure 4As shown, the present invention discloses a magnetostrictive active variable stiffness vibration damper with dynamic prestress and controllable force. The top of the first giant magnetostrictive material rod 8-1 mates with the groove at the bottom of the first permanent magnet 9-1, and the bottom of the first giant magnetostrictive material rod 8-1 mates with the groove at the top of the second permanent magnet 9-2. Following this, the second giant magnetostrictive material rod 8-2, the third permanent magnet 9-3, the third giant magnetostrictive material rod 8-3, and the fourth permanent magnet 9-4 are arranged in descending order. The first permanent magnet 9-1, the second permanent magnet 9-2, the third permanent magnet 9-3, and the fourth permanent magnet 9-4 are made of neodymium iron boron material. Their magnetization direction is from bottom to top, with the north pole at the top and the south pole at the bottom. Magnetic flux flows from the north pole of the first permanent magnet 9-1 into the diamond-shaped prestressing mechanism 3, along the flexible beams on both sides of the diamond-shaped prestressing mechanism 3, and returns to the south pole of the fourth permanent magnet 9-4.

[0023] As a preferred embodiment of the present invention, the diamond-shaped preloading mechanism 3 uses a magnetic conductive material with a high elastic modulus, such as spring steel, silicon steel or alloy structural steel, which can provide high structural rigidity and achieve magnetic circuit closure.

[0024] As a preferred embodiment of the present invention, the top cover 1, the cylindrical shell 3, the output rod 4, the disc spring 5, and the base 12 are made of non-magnetic materials.

[0025] The operating principle of the present invention is as follows: the output rod 4 is connected to an external device. When the external device is subjected to vibration, an excitation force is generated. This excitation force is transmitted along the output rod 4 of the vibration damper, through the diamond-shaped preload mechanism 3, and then to the three giant magnetostrictive rods 8-1 to 8-3 and the four permanent magnets 9-1 to 9-4, before being transmitted to the force sensor 11. The force sensor 11 transmits the real-time external excitation force signal to the controller, which calculates and outputs two sets of drive currents. One set of drive currents is output to the first excitation coil 6-1 and the third excitation coil 6-3, adjusting the internal magnetic field states of the first and third giant magnetostrictive rods 8-1 and 8-3, respectively. This causes the output forces generated by the first and third giant magnetostrictive rods 8-1 and 8-3 to preload the second giant magnetostrictive rod 8-2. By varying the current intensity, the prestress applied to the second giant magnetostrictive rod 8-2 can be dynamically adjusted. The other set of drive currents is output to the second excitation coil 6-2. By adjusting the current of the second excitation coil 6-2, the magnetic field strength in the second giant magnetostrictive material rod 8-2 is changed, so that the elastic modulus of the second giant magnetostrictive material rod 8-2 is changed, thereby changing the material stiffness and damping of the second giant magnetostrictive material rod 8-2, and further changing the overall structural stiffness and damping of the vibration absorber, thereby achieving a change in the resonance frequency of the vibration absorber, so that the overall system composed of the external device and the vibration absorber avoids the excitation frequency of the external vibration source, reducing the risk of resonance of the overall system.

[0026] The invention has the characteristics of compact structure, fast frequency response, low driving voltage, easy installation, etc. It is suitable for active and passive vibration control fields such as aerospace and precision mechanical equipment vibration reduction.

Claims

1. A magnetostrictive active variable stiffness vibration absorber with controllable dynamic prestress, characterized by: The invention comprises a top cover (1), a cylindrical shell (2), a diamond-shaped pre-stressing mechanism (3), an output rod (4), a disc spring (5), an excitation coil (6), a coil skeleton (7), a giant magnetostrictive material rod (8), a permanent magnet (9), a force sensor (11) and a base (12); wherein the top end of the cylindrical shell (2) is fixedly connected to the top cover (1) by a thread, and the bottom end of the cylindrical shell (2) is fixedly connected to the base (12) by a bolt; a notch is left on the side wall of the cylindrical shell (2), and a cut is left on the bottom of the cylindrical shell (2) for connecting a lead wire to the force sensor (11); the top threaded rod of the output rod (4) passes through the through hole in the center of the top cover (1), the output rod (4) is connected to the top cover (1) by the disc spring (5), and the bottom end of the output rod (4) is fixedly connected by a thread The invention relates to a diamond pre-pressing mechanism (3) and a plurality of magnetostrictive material rods (8) and permanent magnets (9) which are fixedly connected to the threaded holes at the top of the diamond pre-pressing mechanism (3); arched beams are symmetrically arranged on both sides of the diamond pre-pressing mechanism (3); a plurality of magnetostrictive material rods (8) and permanent magnets (9) are sequentially installed in the inner cavity of the diamond pre-pressing mechanism (3) from top to bottom through interference fit, wherein the arched beams symmetrically arranged on both sides of the diamond pre-pressing mechanism (3) are in contact with the permanent magnets (9); a coil skeleton (7) is installed outside the magnetostrictive material rods (8) and the permanent magnets (9); an excitation coil (6) is respectively wound around each coil skeleton (7); the bottom of the diamond pre-pressing mechanism (3) is fixedly connected to the threaded hole at the center of the force sensor (11) through a threaded rod (10); and the force sensor (11) is fixed to the bottom of the inner cavity of the cylindrical shell (2) through a bottom cover (12).

2. The magnetostrictive active variable stiffness vibration absorber with controllable dynamic prestress according to claim 1, characterized in that: The top permanent magnet has a groove at its bottom, the bottom permanent magnet has a groove at its top, and the middle permanent magnet has grooves at its top and bottom. The top and bottom of the giant magnetostrictive material rod (8) fit the grooves at the top and / or bottom of the permanent magnet (9).

3. The magnetostrictive active variable stiffness vibration absorber with controllable dynamic prestress according to claim 1, characterized in that: The permanent magnet (9) is made of neodymium iron boron material, and its magnetization direction is from bottom to top, with the top being the N pole and the bottom being the S pole; the magnetic flux flows out from the N pole of the permanent magnet at the top and enters the rhombus preloading mechanism (3), along the flexible beams on both sides of the rhombus preloading mechanism (3) and returns to the S pole of the permanent magnet at the bottom.

4. The magnetostrictive active variable stiffness vibration absorber with controllable dynamic prestress according to claim 1, characterized in that: The diamond-shaped pre-pressing mechanism (3) adopts a magnetic conductive material with a high elastic modulus, provides high structural rigidity, and realizes magnetic circuit closure.

5. The magnetostrictive active variable stiffness vibration absorber with controllable dynamic prestress according to claim 4, characterized in that: The magnetic conductive material with high elastic modulus is made of spring steel, silicon steel or alloy structural steel.

6. The magnetostrictive active variable stiffness vibration absorber with controllable dynamic prestress according to claim 1, characterized in that: The top cover (1), cylindrical shell (3), output rod (4), disc spring (5) and base (12) are made of non-magnetic conductive materials.

7. The magnetostrictive active variable stiffness vibration absorber with controllable dynamic prestress according to claim 1, characterized in that: The number of the giant magnetostrictive material rods (8) is three, namely a first giant magnetostrictive material rod (8-1), a second giant magnetostrictive material rod (8-2), and a third giant magnetostrictive material rod (8-3); the number of the permanent magnets (9) is four, namely a first permanent magnet (9-1), a second permanent magnet (9-2), a third permanent magnet (9-3), and a fourth permanent magnet (9-4); the number of the coil skeletons (7) is three, namely a first coil skeleton (7-1), a second coil skeleton (7-2), and a third coil skeleton (7-3); and the number of the corresponding excitation coils (6) is also three, namely a first excitation coil (6-1), a second excitation coil (6-2), and a third excitation coil (6-3).

8. The control method of a magnetostrictive active variable stiffness vibration absorber with controllable dynamic prestressing force according to any one of claims 1 to 7, characterized in that: The output rod (4) is connected to an external device. When the external device is vibrated to generate an exciting force, the exciting force is transmitted along the output rod (4) of the shock absorber, passes through the diamond preload mechanism (3), the giant magnetostrictive material rod (8), and the permanent magnet (9), and is transmitted to the force sensor (11); the force sensor (11) sends the external exciting force signal monitored in real time to the controller, and the controller calculates and outputs two groups of driving currents, one of which is output to the excitation coils at both ends to adjust the internal magnetic field state of the giant magnetostrictive material rods at both ends, so that the output forces generated by the giant magnetostrictive material rods at both ends form a magnetic field on the giant magnetostrictive material rod in the middle. prestressing; changing the current intensity to dynamically adjust the prestress of the giant magnetostrictive material rod in the middle; another set of driving currents is output to the middle excitation coil; by adjusting the current of the middle excitation coil, the magnetic field intensity in the middle giant magnetostrictive material rod is changed, so that the elastic modulus of the middle giant magnetostrictive material rod is changed, thereby changing the material stiffness and damping of the middle giant magnetostrictive material rod, further changing the overall structural stiffness and damping of the shock absorber, realizing the change of the shock absorber resonant frequency, so that the overall system composed of the external device and the shock absorber avoids the excitation frequency of the external vibration source, and reduces the risk of resonance of the overall system.

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