A space cam type multi-stage quasi-zero stiffness ultra-low frequency vibration isolator capable of capturing high-entropy energy

Abstract

A space cam type multi-stage quasi-zero stiffness ultra-low frequency vibration isolator capable of capturing high-entropy energy belongs to the technical field of vibration isolation and vibration energy capture. The problem that traditional quasi-zero stiffness vibration isolation devices are difficult to adapt to multi-stage vibration isolation load due to structural limitations is solved, and sensor self-power supply and intelligent detection are realized. The bottom of the positive stiffness spring and guide beam assembly is connected to the base through a bolt and nut, the sliding end is connected to the load platform through a bolt and nut, four groups of negative stiffness piezoelectric beam assemblies are installed on the support in clockwise order, the vertical guide rail of each negative stiffness piezoelectric beam assembly is connected to the load platform through a bolt and nut, four moving cam sliding grooves are connected to the load platform through a bolt and nut in clockwise order, and the deep groove ball bearing in the negative stiffness piezoelectric beam assembly slides into the corresponding cam sliding groove to form a cam pair. The present application can realize multi-stage load quality vibration isolation and sensor self-power supply, and has the advantages of novel structure, low frequency vibration isolation, wide frequency energy capture and flexible design.

Description

Technical Field

[0001] This invention relates to a piezoelectric self-powered multi-stage quasi-zero stiffness vibration isolation device, specifically to a spatial cam-type multi-stage quasi-zero stiffness ultra-low frequency vibration isolator capable of capturing high-entropy energy, belonging to the field of vibration isolation and vibration energy harvesting technology. Background Technology

[0002] Vibration in engineering systems can severely affect the accuracy of precision equipment and reduce the lifespan of instruments. Furthermore, in environments where manual operation and external power supply are inconvenient, powering small sensors monitoring vibration signals to enable signal transmission is a significant challenge. Most quasi-zero stiffness isolators can only isolate a specific load mass, failing to adapt to multiple load masses, greatly reducing their practicality and adaptability. Currently, there are two methods to achieve multi-stage quasi-zero stiffness vibration isolation: one is based on parallel connection of positive and negative stiffness to obtain quasi-zero stiffness by connecting positive stiffness with structures having multiple segments of negative stiffness; the other combines metamaterial design concepts, assembling quasi-zero stiffness units with different load-bearing capacities into multi-layer metamaterials to achieve multi-stage quasi-zero stiffness. During isolator operation, piezoelectric materials are used to collect the energy generated by the deformation of quasi-zero stiffness elements to power the sensor function. The nonlinear widening of the energy harvesting bandwidth introduced by quasi-zero stiffness is a new research hotspot.

[0003] However, in existing technologies, multilayer metamaterial structures are fabricated using additive manufacturing of non-metallic materials. When used for vibration isolation, these structures undergo plastic deformation, disrupting their original quasi-zero stiffness characteristics and resulting in unstable performance. A typical parallel structure is the cam-spring structure, as seen in the literature "Li Y, Wu Z, Peng Y, Yao S, Zhou J, Full-band vibrationisolation of multi-step quasi-zero stiffness systems, Int. J. Mech. Sci.2024;274:109277.", where the negative stiffness is actually provided by a horizontal spring.

[0004] Secondly, current piezoelectric energy harvesting devices have limited maximum output power under optimal operating conditions. For example, in the literature "Wang M, Xia Y, Pu H, Sun Y, Ding J, Luo J, Xie S, Peng Y, Zhang Q, Li Z, Piezoelectric Energy Harvesting from Suspension Structures with Piezoelectric Layers, Sensors 2020," ordinary planar structures can only effectively harvest energy at a certain resonant frequency. Furthermore, the maximum strain of the piezoelectric material is limited, resulting in poor output performance and failing to meet the self-powered monitoring requirements of sensors. Summary of the Invention

[0005] The purpose of this invention is to provide a spatial cam-type multi-stage quasi-zero stiffness ultra-low frequency vibration isolator that can capture high-entropy energy, so as to solve the problem that traditional quasi-zero stiffness vibration isolation devices are limited by structure and difficult to adapt to multi-stage vibration isolation loads. At the same time, piezoelectric materials are added to collect vibration energy, so as to realize the self-powered sensor and intelligent detection.

[0006] A spatial cam-type multi-stage quasi-zero stiffness ultra-low frequency vibration isolator capable of capturing high-entropy energy includes a base, a bracket, a negative stiffness piezoelectric beam assembly, a movable cam slide, a loading platform, a positive stiffness spring, and a guide beam assembly.

[0007] The bottom of the positive stiffness spring and guide beam assembly is connected to the base with bolts and nuts. The four sets of negative stiffness piezoelectric beam assemblies are installed on the bracket according to the corresponding mounting holes in a clockwise order and tightened with bolts and nuts. The vertical guide rail of each negative stiffness piezoelectric beam assembly is connected to the loading platform with bolts and nuts. The four moving cam slides are connected to the loading platform with bolts and nuts in a clockwise order. At the same time, the deep groove ball bearing in the negative stiffness piezoelectric beam assembly slides into the corresponding cam slide to form a cam pair.

[0008] Preferred configuration: The vertical linear guide rail is installed onto the loading platform using bolts and nuts, and the cam slides are installed onto the corresponding positions on the loading platform using bolts and nuts in a circumferential array.

[0009] Preferred: The positive stiffness spring and guide beam assembly includes a guide rod fixing seat, a vertical guide rod, a spring, a linear bearing, and a linear bearing support seat. The guide rod fixing seat is installed onto the base using bolts and nuts, and the linear bearing support seat and the loading platform are fixed together using bolts and nuts. The spring provides positive stiffness, such as... Figure 2 The positive stiffness curve shown is a linear function.

[0010] Preferred: The negative stiffness piezoelectric beam assembly includes an elastic matrix, a piezoelectric material, and a fixed support. The piezoelectric material is pasted at the negative Poisson's ratio position of the elastic matrix and the two are of equal width. The elastic matrix has a threaded hole at its end. Bolts and nuts are used to fix the two ends of the elastic matrix to the piezoelectric beam mounting base and the piezoelectric beam sliding support, respectively, through the threaded hole at the end of the elastic matrix.

[0011] Preferably, a hexagonal copper stud, a deep groove ball bearing, and a set screw constitute the follower of the cam pair. The follower is screwed into the threaded hole of the piezoelectric beam sliding support via the hexagonal copper stud. The cam slide is fixed to the platform with bolts and nuts. The deep groove ball bearing cooperates with the cam slide to form a cam pair, achieving negative stiffness through force decomposition. Figure 2 The negative stiffness curve shown is a periodic function.

[0012] Compared with existing products, the present invention has the following advantages:

[0013] 1. A spatial cam-type multi-stage quasi-zero stiffness ultra-low frequency vibration isolator capable of capturing high-entropy energy, which obtains negative stiffness through force decomposition, significantly different from the traditional spring cam structure. The cam groove can be extended and designed into different curve shapes, such as constant acceleration and deceleration motion curves, cosine acceleration curves, and polynomial motion curves. Furthermore, multiple negative stiffness ranges can be obtained through the periodic change of the cam curve, which can then be coupled with a positive stiffness spring to obtain multi-stage quasi-zero stiffness. Therefore, this invention has the advantages of novel structure, adaptability to multi-stage loads, and serializability.

[0014] 2. The negative stiffness piezoelectric beam assembly of the present invention provides negative stiffness while cooperating with the cam groove, and can capture vibration energy through the deformation of the elastic matrix. Due to the nonlinear effect introduced by the quasi-zero stiffness, the energy capture bandwidth is expanded, and high entropy energy can be captured in a lower frequency band. Therefore, the present invention has the advantage of being able to perform low-frequency energy capture in a wider frequency band.

[0015] 3. The piezoelectric beam elastic matrix of the present invention has negative Poisson's ratio structural characteristics. The axial and radial stresses on the elastic matrix always have the same sign, which increases the total stress on the piezoelectric material compared to the traditional positive Poisson's ratio beam piezoelectric matrix. 31 The piezoelectric mode of this invention is d. 31 and d 32 The invention utilizes a composite energy harvesting method, thus contributing to improved energy harvesting efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a space cam-type multi-stage quasi-zero stiffness ultra-low frequency vibration isolator that can capture high-entropy energy.

[0017] Figure 2 Positive / negative stiffness components and their superimposed force-displacement curves;

[0018] Figure 3 Exploded view of the relative positions of the base and the support;

[0019] Figure 4 This is an exploded view of the installation method of the positive stiffness spring, guide beam assembly, and base;

[0020] Figure 5 This is an exploded diagram illustrating the installation method of the cam slide, vertical linear guide rail, and loading platform.

[0021] Figure 6 This is a schematic diagram of an explosion of a negative stiffness piezoelectric beam assembly;

[0022] Figure 7 This is an exploded view showing the relative positions of the negative stiffness piezoelectric beam assembly and its support.

[0023] In the diagram: 1—Base, 2—Bracket, 3—Negative stiffness piezoelectric beam assembly, 4—Moving cam slide, 5—Loading platform, 6—Positive stiffness spring and guide beam assembly, 7—Bracket mounting hole, 8—Guide rod fixing seat, 9—Spring, 10—Vertical guide rod, 11—Linear bearing support seat, 12—Linear bearing, 13—Linear bearing mounting hole, 14—Linear bearing fixing hole, 15—Guide rod locking hole, 16—Support fixing hole, 17—Support mounting hole, 18—Vertical slider, 19—Vertical linear guide rail, 20—Bearing support mounting hole, 21—Bearing support fixing hole 22—Cam slide mounting hole; 23—Fixed hole; 24—Vertical guide rail mounting hole; 25—Piezoelectric beam rear fixing plate; 26—Piezoelectric material; 27—Elastic matrix; 28—Piezoelectric beam mounting seat; 29—Vertical slider fixing seat; 30—Piezoelectric beam sliding support; 31—Threaded hole; 32—Hexagonal copper stud; 33—Set screw; 34—Deep groove ball bearing; 35—Horizontal linear guide rail; 36—Horizontal slider; 37—Piezoelectric beam front fixing plate; 38—Piezoelectric beam assembly mounting hole; 39—Vertical guide rail support mounting hole; 40—Horizontal guide rail mounting hole. Detailed Implementation

[0024] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0025] like Figures 1 to 7 As shown, the spatial cam-type multi-stage quasi-zero stiffness ultra-low frequency vibration isolator that can capture high-entropy energy according to the present invention includes a base 1, a bracket 2, a negative stiffness piezoelectric beam assembly 3, a movable cam slide 4, a loading platform 5, and a positive stiffness spring and guide beam assembly 6.

[0026] The stiffness spring and guide beam assembly 6 includes a guide rod fixing seat 8, a spring 9, a vertical guide rod 10, a linear bearing support seat 11, and a linear bearing 12. Its connection structure is as follows: The bracket 2 is installed onto the base 1 according to the position of the bracket mounting hole 7 using bolts and nuts. The vertical guide rod 10 is inserted into the corresponding shaft hole of the guide rod fixing seat 8 and locked at the bottom using bolts and nuts through the guide rod locking hole 15. The vertical guide rod 10 passes through the spring 9. The linear bearing 12 is placed into the linear bearing mounting hole 13 of the linear bearing support seat 11. The linear bearing 12 is positioned and tightened using bolts and nuts through the linear bearing fixing hole 14. The guide rod fixing seat 8 is installed onto the base 1 according to the corresponding positions of the support fixing hole 16 and the support mounting hole 17 using bolts and nuts.

[0027] Further: Slide the vertical slider 18 into the vertical linear guide rail 19, and use machine screws and nuts to fix the four sets of linear guide rails to the loading platform 5 according to the position of the vertical guide rail mounting hole 24. Use bolts and nuts to install the four moving cam slides 4 in a circular array to the loading platform 5 according to the position of the cam slide hole 22. Tighten the loading platform 5 and the linear bearing support 11 with bolts and nuts according to the position of the bearing support mounting hole 20 and the bearing support fixing hole 21.

[0028] Further: The negative stiffness piezoelectric beam assembly 3 includes a piezoelectric beam rear fixing plate 25, piezoelectric material 26, elastic matrix 27, piezoelectric beam fixing seat 28, piezoelectric beam sliding support 30, deep groove ball bearing 34, set screw 33, horizontal linear guide rail 35, horizontal slider 36, and piezoelectric beam front fixing plate 37. The connection structure is as follows: the piezoelectric material 26 is pasted on the part of the elastic substrate 27 with a negative Poisson's ratio at the root. The rear fixing plate 25 of the piezoelectric beam, the piezoelectric beam fixing seat 28 and the elastic substrate 27 with pasted piezoelectric material are fastened with bolts and nuts according to the corresponding mounting holes. The hexagonal copper stud 32 is screwed into the threaded hole 31 of the piezoelectric beam sliding support 30 and tightened. The set screw 33 is inserted into the deep groove ball bearing 34 and screwed into the hexagonal copper stud 32. The front fixing plate 37 of the piezoelectric beam, the piezoelectric beam sliding support 30 and the elastic substrate 27 with pasted piezoelectric material are fastened with bolts and nuts according to the corresponding mounting holes. The horizontal slider 36 is slid into the horizontal linear guide 35 and the horizontal slider 36 is installed at the corresponding position at the bottom of the piezoelectric beam sliding support 30 with machine screws.

[0029] Further: The vertical slider fixing seat 29 is installed on the bracket 2 according to the position of the vertical guide rail support mounting hole 39 by bolts and nuts, and the negative stiffness piezoelectric beam assembly 3 is installed on the bracket 2 according to the position of the piezoelectric beam assembly mounting hole 38 and the horizontal guide rail mounting hole 40.

[0030] Further: Following a clockwise sequence, use bolts and nuts to install the remaining three sets of negative stiffness piezoelectric beam assemblies 3 and vertical slider fixing seats 29 to their corresponding positions on the bracket 2.

[0031] Further: Use machine screws to install the vertical slider 18 and the vertical slider fixing seat 29 together, and put the deep groove ball bearing 34 into the groove of the movable cam slide 4 to complete the cam pair engagement.

[0032] The shape of the negative Poisson's ratio area of ​​the elastic matrix 27 is not limited, and can be in the form of an internal hexagonal array, a chiral structure, or a rotating rigid body negative Poisson's ratio structure, etc.

[0033] The cam pair causes the moving cam slide 4 to move up and down reciprocally with the loading platform 5, which is converted into alternating stress and strain on the negative stiffness piezoelectric beam assembly 3. Due to the positive piezoelectric effect of the piezoelectric material 26, its mechanical energy is converted into electrical energy and supplied to the power-consuming equipment through the wire.

[0034] The motion mode of the negative stiffness piezoelectric beam assembly 3 is affected by the curve of the moving cam groove 4. The shape of the moving cam groove is not limited and can be a constant acceleration and deceleration motion curve, a cosine acceleration curve, or a polynomial motion curve.

[0035] This embodiment is merely an exemplary description of this patent and does not limit its scope of protection. Those skilled in the art can make partial changes to it, as long as they do not exceed the spirit and essence of this patent and are all within the scope of protection of this patent.

Claims

1. A spatial cam-type multi-stage quasi-zero stiffness ultra-low frequency vibration isolator capable of capturing high-entropy energy, characterized in that: It includes a base (1), a bracket (2), a negative stiffness piezoelectric beam assembly (3), a moving cam slide (4), a loading platform (5), and a positive stiffness spring and guide beam assembly (6). The positive stiffness spring and guide beam assembly (6) includes a guide rod fixing seat (8), a spring (9), a vertical guide rod (10), a linear bearing support seat (11), and a linear bearing (12); its connection structure is as follows: the bracket (2) is installed on the base (1) according to the position of the bracket mounting hole (7) by bolts and nuts, the vertical guide rod (10) is inserted into the corresponding shaft hole of the guide rod fixing seat (8) and the bottom of the vertical guide rod is locked by bolts and nuts through the guide rod locking hole (15), the vertical guide rod (10) is inserted into the spring (9), the linear bearing (12) is placed in the linear bearing mounting hole (13) of the linear bearing support seat (11), the linear bearing (12) is positioned and tightened by bolts and nuts through the linear bearing fixing hole (14), and the guide rod fixing seat (8) is installed on the base (1) according to the corresponding position of the support fixing hole (16) and the support mounting hole (17) by bolts and nuts; The vertical slider (18) slides into the vertical linear guide (19). The four sets of linear guides are fixed to the loading platform (5) according to the position of the vertical guide mounting hole (24) using machine screws and nuts. The four movable cam slides (4) are installed on the loading platform (5) in a circular array according to the position of the cam slide mounting hole (22) using bolts and nuts. The loading platform (5) and the linear bearing support (11) are fastened with bolts and nuts according to the position of the bearing support mounting hole (20) and the bearing support fixing hole (21). The negative stiffness piezoelectric beam assembly (3) includes a rear fixing plate (25) for the piezoelectric beam, piezoelectric material (26), an elastic matrix (27), a piezoelectric beam fixing seat (28), a piezoelectric beam sliding support (30), a deep groove ball bearing (34), a set screw (33), a horizontal linear guide (35), a horizontal slider (36), and a front fixing plate (37) for the piezoelectric beam. Its connection structure is as follows: the piezoelectric material (26) is pasted onto the part of the elastic matrix (27) at the root where a negative Poisson's ratio is present. The rear fixing plate (25), the piezoelectric beam fixing seat (28), and the elastic matrix (27) with the pasted piezoelectric material are then connected using bolts and nuts. Tighten the corresponding mounting holes, screw the hexagonal copper stud (32) into the threaded hole (31) of the piezoelectric beam sliding support (30) and tighten it. Insert the set screw (33) into the deep groove ball bearing (34) and screw the set screw (33) into the hexagonal copper stud (32). Tighten the front fixing plate (37), the piezoelectric beam sliding support (30) and the elastic substrate (27) with the piezoelectric material pasted on according to the corresponding mounting holes with bolts and nuts. Slide the horizontal slider (36) into the horizontal linear guide (35) and install the horizontal slider (36) at the corresponding position at the bottom of the piezoelectric beam sliding support (30) with machine screws. The vertical slider fixing seat (29) is installed on the bracket (2) according to the position of the vertical guide rail support mounting hole (39) by bolts and nuts. The negative stiffness piezoelectric beam assembly (3) is installed on the bracket (2) according to the position of the piezoelectric beam assembly mounting hole (38) and the horizontal guide rail mounting hole (40). In a clockwise order, the remaining three sets of negative stiffness piezoelectric beam assemblies (3) and vertical slider fixing seat (29) are installed on the corresponding positions of the bracket (2) by bolts and nuts. The vertical slider (18) and vertical slider fixing seat (29) are installed together by machine screws. The deep groove ball bearing (34) is placed in the groove of the moving cam slide (4) to complete the cam pair engagement.

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