Torsional negative stiffness vibration isolation device based on pre-stretched spring

Abstract

The application discloses a torsional negative stiffness vibration isolation device based on pre-tensioned springs and belongs to the technical field of vibration isolation devices.The vibration isolation device can normally transmit the rated torsional motion of a system, reduces the torsional dynamic stiffness of the system, lowers the natural frequency, realizes the torsional vibration isolation of shaft system components under low-frequency and ultralow-frequency bands, and has a good vibration isolation effect.Two ends of two connecting rod devices are connected in a hinged manner on an inner part and corresponding sliding blocks respectively, the two sliding blocks are limited in displacement directions through sliding grooves fixed on the inner side of an outer part, and elastic elements generate acting forces on the two sliding blocks and apply torsional moments on the inner part through the two connecting rod devices.The application introduces a negative stiffness device, reduces the torsional dynamic stiffness of a shaft system structure, lowers the natural frequency of the system in the torsional direction, and realizes the vibration isolation function under low-frequency and ultralow-frequency bands.

Description

Technical Field

[0001] This invention belongs to the technical field of vibration isolation devices, specifically relating to a torsional vibration isolation device. Background Technology

[0002] Rotating machinery is widely used in aerospace, machining, energy, and rail transportation. Torsional vibration is a common dynamic phenomenon in rotating machinery systems, which can disrupt the smooth operation of mechanical equipment and even cause serious consequences such as damage to related components. In precision engineering, torsional vibration can affect the accuracy of precision instruments, and severe torsional vibration can also cause noise problems. Passive vibration isolation has advantages such as requiring no external energy input, simple structure, light weight, ease of implementation, and reliable performance, and has been widely used in traditional engineering fields. However, due to its own structural characteristics, its stability is poor, it lacks adjustability, and it cannot isolate torsional vibrations in the low-frequency or even ultra-low-frequency bands.

[0003] Traditional vibration isolation technology is not ideal for low-frequency, especially ultra-low-frequency vibration. Quasi-zero stiffness isolators have high static stiffness and low dynamic stiffness, which can effectively improve system stability and static load-bearing capacity, and have superior low-frequency vibration isolation performance, which has attracted widespread attention from scholars at home and abroad. The concept of high static stiffness and low dynamic stiffness was first proposed by British engineer Molyneux[1] in 1957. The so-called high static stiffness and low dynamic stiffness means that while having high static stiffness, it also has low dynamic stiffness. High static stiffness can ensure that the static deformation of the system is small; low dynamic stiffness reduces the natural frequency of the system, which can expand the vibration isolation range.

[0004] As for nonlinear torsional isolators that isolate low-frequency torsional vibrations, there are relatively few research results at home and abroad. Hou et al.[2] proposed a variety of functional joint mechanisms that can output constant torque and have potential applications in human joint rehabilitation equipment, but did not involve the application of the structure in the field of vibration isolation. Zhou Jiaxi et al. developed a torsional quasi-zero stiffness isolator by connecting a pre-compressed cam roller mechanism in parallel with vulcanized rubber with positive torsional stiffness (application publication number CN104455199A, application publication date 2015.03.25). However, its structure is relatively complex, the cam mechanism has high requirements for processability, and the pre-compressed spring structure naturally has shortcomings such as poor stability.

[0005] [1]Molyneux,WGThe Support of an Aircraft for Ground ResonanceTests:A Survey of Available Methods[J].Aircraft Engineering and AerospaceTechnology,1958,30(6):160-166.

[0006] [2]Hou CW,Lan C C.Functional joint mechanisms with constant-torqueoutputs[J].Mechanism&Machine Theory,2013,62:166-181. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention proposes a torsional negative stiffness vibration isolation device based on a pre-tensioned spring. While still transmitting the rated torsional motion of the system normally, it reduces the torsional dynamic stiffness of the system, thereby lowering the natural frequency. This achieves isolation of shaft components from torsional vibrations in the low-frequency and ultra-low-frequency bands, resulting in a better vibration isolation effect.

[0008] The technical solution adopted in this invention is: a torsional negative stiffness vibration isolation device based on a pre-tensioned spring, comprising an inner component, an outer component, an elastic element, two sliding grooves, two sliders, and two connecting rod devices; the two connecting rod devices are respectively hinged to the inner component and the corresponding sliders at both ends; the two sliders are restricted in their displacement direction by sliding grooves fixed to the inner side of the outer component; the elastic element generates a force on the two sliders and applies a torsional torque to the inner component through the two connecting rod devices.

[0009] Compared with the prior art, the present invention has the following advantages:

[0010] 1. This invention reduces the torsional dynamic stiffness of the shaft system by introducing a negative stiffness device, thereby reducing the natural frequency of the system in the torsional direction and achieving vibration isolation at low and even ultra-low frequencies.

[0011] 2. This invention has advantages in terms of improved performance, quality, precision and efficiency; savings in energy consumption, raw materials and processes; and ease of processing, operation, control and use. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating the installation and working principle of the present invention;

[0013] Figure 2 This is a longitudinal cross-sectional view of the present invention;

[0014] Figure 3 This is a side view of the present invention;

[0015] Figure 4 This is a schematic diagram of the structure of the vibration isolation device after rotation;

[0016] Figure 5 This is the curve showing the relationship between the restoring torque of this vibration isolation device and the rotation angle;

[0017] Figure 6 This is the curve showing the relationship between the torsional equivalent stiffness of this vibration isolation device and the rotation angle;

[0018] Figure 7 This is a schematic diagram of the fourth implementation method. Figure 1 ;

[0019] Figure 8 This is a schematic diagram of the fourth implementation method. Figure 2 ;

[0020] Figure 9 This is a schematic diagram of embodiment seven;

[0021] The components are: 1. Inner parts; 2. Slide groove; 3. Slider; 4. Elastic element; 5. Linkage device; 6. Outer parts. Detailed Implementation

[0022] Specific implementation method one: Refer to Figures 1 to 9 This embodiment provides a torsional negative stiffness vibration isolation device based on a pre-tensioned spring, including an inner component 1, an outer component 6, an elastic element 4, two sliding grooves 2, two sliders 3, and two connecting rod devices 5. The two connecting rod devices 5 are respectively hinged to the inner component 1 and the corresponding sliders 3. The displacement direction of the two sliders 3 is restricted by the sliding grooves 2 fixed inside the outer component 6. The elastic element 4 generates a force on the two sliders 3 and applies a torsional torque to the inner component 1 through the two connecting rod devices 5.

[0023] Specific Implementation Method Two: Refer to Figures 1 to 9 This embodiment further defines the first embodiment. In this embodiment, both slides 2 cause the slider 3 to move along the direction of approaching and moving away from the inner component 1. Other components and connection methods are the same as in the first embodiment.

[0024] Specific Implementation Method Three: Refer to Figures 1 to 4 This embodiment further defines Specific Embodiment Two. In this embodiment, the inner component 1 and the outer component 6 are concentrically arranged shaft components, serving as input and output connection shafts, respectively. Other components and connection methods are the same as in Specific Embodiment Two.

[0025] Specific implementation method four, refer to Figures 7 to 8 This embodiment further defines the second specific embodiment. In this embodiment, the inner component 1 and the outer component 6 are non-shaft components, which are the vibration isolation structure and the external structure, respectively.

[0026] The specific practical applications of this vibration isolation device are not limited to, for example... Figure 1The coupling shown can also be installed at the rotational connection of other torsional systems such as suspensions and gimbals. The inner component 1 and outer component 6 can be replaced with non-shaft structures. The two ends of the connecting rod device 5 and the sliding groove 2 can be installed on the vibration-isolated structure and the external structure, respectively. This vibration isolation device provides torsional negative stiffness to the structure, reducing the natural frequency corresponding to the system's rotational mode, and thus isolating vibrations in the rotational direction. Figure 7 As shown in Figure 8;

[0027] Specific Implementation Method Five: Refer to Figures 2 to 9 This embodiment further defines the elastic element 4 described in specific embodiments three or four. In this embodiment, the elastic element 4 adopts a pre-tensioned spring, a flexible beam structure, or other elastic structures. Other components and connection methods are the same as in specific embodiments three or four.

[0028] Specific Implementation Method Six: Refer to Figures 2 to 8 This embodiment further defines specific embodiment five. In this embodiment, there is one pretension spring, and both ends of the pretension spring are connected to two sliders 3. Other components and connection methods are the same as in specific embodiment five.

[0029] Compared with the existing pre-compression spring cam structure, the pre-tensioned spring has a simpler structure, saves costs, and has strong adjustability. The number of springs required for the vibration isolation structure is reduced from two to one, thus significantly improving the system reliability and providing better stability.

[0030] Specific Implementation Method Seven: Refer to Figure 9 This embodiment further defines specific embodiment five. In this embodiment, there are two pretension springs, and both ends of each pretension spring are connected to the outer component 6 and a corresponding slider 3. Other components and connection methods are the same as in specific embodiment five.

[0031] The slide 2 can be replaced by other limiting devices such as slide rails that restrict the movement of the slider in one direction;

[0032] Under the condition that the connection relationship of each structure remains unchanged, the relative installation position of the pretension spring and the connecting rod device 5 within the structure can be changed.

[0033] This vibration isolation device combines rigid rods, sliders, and springs to reduce torsional dynamic stiffness and achieve low-frequency vibration isolation of the system.

[0034] The working principle of vibration isolation device installation is as follows: Figure 1 As shown, it is installed between two rotating shafts, acting as a coupling. At the same time, through its internal nonlinear structure, it provides negative stiffness to the entire rotating shaft system, thus isolating the torsional disturbance transmitted into the system by the torque.

[0035] When inner component 1 and outer component 6 rotate relative to each other, the vibration isolation structure operates as follows: Figure 4 As shown, since the pre-tension spring has a pre-tension amount, a torque in the same direction of rotation will be applied to the inner part 1 through the connecting rod device 5.

[0036] Mechanical analysis of the vibration isolation structure reveals that, after relative rotation, the magnitude of the torque experienced by internal component 1 is:

[0037]

[0038] Differentiating the torque with respect to the rotation angle, we obtain the magnitude of the torsional equivalent rotational stiffness of the vibration isolation system as follows:

[0039]

[0040] Where θ is the relative rotation angle between the inner and outer shafts, φ is the rotation angle of the connecting rod, which can be derived from geometric relationships, k is the stiffness of the pre-tension spring, L0 is the original length of the pre-tension spring, L is the length of the connecting rod, and R is the radius of the inner shaft section.

[0041] Based on the torque and equivalent stiffness formula derived above, the curves showing the torsional restoring torque and equivalent torsional stiffness as a function of rotation angle can be plotted as follows: Figure 5 As shown in Figure 6, by Figure 5 It can be seen that the torque of the system near the static equilibrium position decreases with increasing rotation angle, indicating that the system has torsional negative stiffness characteristics. This characteristic is... Figure 6 The results can be observed and analyzed more intuitively. The results show that the present invention can reduce the torsional dynamic stiffness of shaft components, reduce the natural frequency of the overall system, and achieve the effect of low-frequency vibration isolation.

[0042] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A torsional negative stiffness vibration isolation device based on a pre-tensioned spring, characterized in that: It includes an inner component (1), an outer component (6), an elastic element (4), two sliding grooves (2), two sliders (3), and two connecting rod devices (5); the two connecting rod devices (5) are hinged to the inner component (1) and the corresponding sliders (3) respectively. The two sliders (3) are restricted in their displacement direction by the sliding grooves (2) fixed inside the outer component (6). The elastic element (4) exerts a force on the two sliders (3) and applies a torsional torque to the inner component (1) through the two connecting rod devices (5). The inner component (1) and the outer component (6) are concentrically arranged shaft components, which are respectively the input and output end connecting shafts. Alternatively, the inner component (1) and the outer component (6) are non-shaft components, which are respectively the vibration isolation structure and the external structure. Both slides (2) cause the slider (3) to move along the direction closer to and away from the inner component (1). The elastic element (4) is a pre-tensioned spring.

2. The torsional negative stiffness vibration isolation device based on a pre-tensioned spring according to claim 1, characterized in that: The number of pre-tensioned springs is one, and the two ends of the elastic element (4) are connected to the two sliders (3).

3. The torsional negative stiffness vibration isolation device based on a pre-tensioned spring according to claim 1, characterized in that: The number of pre-tension springs is two, and the two ends of each pre-tension spring are connected to the outer part (6) and a corresponding slider (3).

Images