Ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping

Abstract

The invention discloses an ultralow-frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping, which relates to the technical field of vibration isolators and comprises an involution disc spring group, a conical rubber spring and a variable stiffness and variable damping unit, conical rubber springs are arranged at the lower ends of the first bearing columns; the rigidity of the conical rubber spring is kept in a non-linear interval through the cushion block; the first bearing column is sleeved with the first folding disc spring set which is located in the upper cavity. The variable rigidity and variable damping unit is arranged in the first bearing column and is in contact with the cushion block; and the lower end of the second bearing column is connected with the top of the variable-rigidity and variable-damping unit. High static and low dynamic characteristics of quasi-zero stiffness and frequency shift vibration suppression of variable stiffness and variable damping are fused, and the effects of vibration isolation of large-range load change in the vertical direction and ultra-low frequency vibration isolation can be achieved by adjusting the current of excitation coils of an inner damper and an outer damper; semi-active vibration control in the vertical direction can be achieved, and passive vibration isolation can be achieved in the transverse direction and the longitudinal direction; the structure is compact, the bearing capacity is high, and the anti-interference capacity is high.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration isolators, and particularly to an ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping. Background Art

[0002] Vibration is a very common physical phenomenon in nature. While bringing us convenience, some vibrations can also cause various harms in engineering applications, such as shortening the service life of equipment, affecting processing accuracy, reducing the operating stability of equipment, and even causing accidents. Therefore, it is necessary to control the unwanted vibration within a suitable range through a vibration isolation device to avoid irreparable damage to equipment or personnel.

[0003] Ultra-low frequency vibration has always been a difficult problem in the field of vibration isolation. A linear vibration isolator can only achieve a vibration isolation effect when the excitation frequency is greater than √2 times the natural frequency of the system. Although reducing the stiffness of the vibration isolator can lower the natural frequency of the system, it will also sacrifice the load-bearing capacity of the system. The quasi-zero stiffness vibration isolator solves the contradiction between the natural frequency and the load-bearing capacity of the linear vibration isolator. By connecting a negative stiffness element in parallel on the basis of a positive stiffness vibration isolation element, the stiffness of the system tends to zero near the static equilibrium position without reducing the load-bearing capacity, making up for the deficiencies of the linear vibration isolator.

[0004] Most of the existing quasi-zero stiffness vibration isolators have a constant design load. When the load changes, the vibration isolation performance of the vibration isolator will drop sharply. Moreover, most of the existing quasi-zero stiffness vibration isolators have complex structures, large occupied spaces, and low load-bearing capacities, which all limit their applications in the actual engineering field. Summary of the Invention

[0005] The object of the present invention is to provide an ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping to solve the problem that the vibration isolation ability of traditional quasi-zero stiffness vibration isolators decreases when facing variable loads.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides an ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping, which includes a first load-bearing column, a first pair of conical disc springs, a conical rubber spring, a cushion block, a housing, a variable stiffness and variable damping unit, and a second load-bearing column; an upper cavity and a lower cavity are arranged inside the housing, and the lower end of the first load-bearing column penetrates through the upper cavity and extends into the lower cavity; the conical rubber spring is arranged between the outer side wall of the lower end of the first load-bearing column and the inner side wall of the lower cavity; the cushion block is arranged between the inner bottom of the lower cavity and the conical rubber spring, and the cushion block is used to keep the stiffness of the conical rubber spring in the non-linear range; the first pair of conical disc springs is sleeved on the first load-bearing column and is located inside the upper cavity; the first load-bearing column is a hollow column, and a cavity is arranged axially in the middle of the first load-bearing column; the variable stiffness and variable damping unit is arranged in the cavity, and the bottom of the variable stiffness and variable damping unit is in contact with the cushion block; the lower end of the second load-bearing column is connected to the top of the variable stiffness and variable damping unit.

[0008] Optionally, it further includes an adjusting nut, which is arranged on the first load-bearing column and above the first pair of conical disc spring sets, and the position of the adjusting nut on the first load-bearing column is adjusted according to the number of disc springs in the first pair of conical disc spring sets.

[0009] Optionally, the conical rubber spring includes a shaft core, a rubber layer, a spacer sleeve and an outer sleeve; the shaft core is arranged at the lower end of the first load-bearing column; the outer side of the outer sleeve is in contact with the inner side wall of the lower cavity, and at least one spacer sleeve is arranged between the shaft core and the outer sleeve, and a rubber layer is respectively arranged between the spacer sleeve and the shaft core, between the spacer sleeve and the outer sleeve, and between adjacent spacer sleeves.

[0010] Optionally, the shaft core is of a conical structure, and a through hole vertically penetrating is arranged at the center of the core shaft, and the through hole is used to accommodate the variable stiffness and variable damping unit.

[0011] Optionally, the outer side wall of the outer sleeve and the inner side wall of the lower cavity are both vertical walls, and the outer side wall of the outer sleeve is in contact with the inner side wall of the lower cavity, the inner side wall of the outer sleeve is a conical wall, the lower end of the conical wall is the end with a smaller inner diameter, and the upper end of the conical wall is the end with a larger inner diameter.

[0012] Optionally, the variable stiffness and variable damping unit includes a piston rod, an inner cylinder body, and an outer cylinder body that are arranged in sequence from the inside out; an inner excitation coil is arranged in the middle of the piston rod, and an outer excitation coil is arranged on the outer wall of the inner cylinder body; a magnetorheological fluid is filled between the inner cylinder body and the outer cylinder body; a piston head is arranged in the middle of the outer wall of the inner cylinder body, and an outer excitation coil is arranged on the piston head; a second pair of mating disc springs is arranged between the upper end of the piston rod and the second load-bearing column, and a helical spring is arranged between the lower end of the piston rod and the cushion block.

[0013] Optionally, a sealing end cover is arranged above the inner cylinder body and the outer cylinder body, and the sealing end cover is used to seal the upper ends of the inner cylinder body and the outer cylinder body.

[0014] Optionally, a guide frame is arranged above the sealing end cover, the second pair of mating disc springs is arranged in the guide frame, and the upper end of the piston rod passes through the guide frame and is connected to the second pair of mating disc springs.

[0015] Optionally, an end cover is arranged at the lower ends of the inner cylinder body and the outer cylinder body, and the end cover is used to seal the lower ends of the inner cylinder body and the outer cylinder body.

[0016] Optionally, a bottom cover is arranged below the end cover, the helical spring is arranged in the bottom cover, the lower end of the piston rod is in contact with the inner bottom surface of the bottom cover, and the outer bottom surface of the bottom cover is in contact with the cushion block.

[0017] The present invention has achieved the following technical effects compared with the prior art:

[0018] Based on the ultra-low frequency quasi-zero stiffness vibration isolator with variable stiffness and variable damping, the present invention combines the high static and low dynamic characteristics of quasi-zero stiffness with the frequency shift and vibration suppression of variable stiffness and variable damping. By adjusting the current of the excitation coils of the internal and external dampers, the vibration isolation effect of large-range load changes in the vertical direction and ultra-low frequency vibration isolation can be achieved; semi-active vibration control in the vertical direction can be realized, and passive vibration isolation can also be realized in the horizontal and longitudinal directions; the structure is compact, the load-bearing capacity is strong, and the anti-interference ability is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a cross-sectional view of the vibration isolator of the present invention;

[0021] Figure 2It is a cross-sectional view of a variable stiffness and variable damping unit;

[0022] Description of reference numerals: 1. First load-bearing column; 2. Adjusting nut; 3. First set of conjoined disc springs; 4. Tapered rubber spring; 401. Axle core; 402. Rubber layer; 403: Spacer sleeve; 404. Outer sleeve; 5. Pad block; 6. Outer shell; 7. Variable stiffness and variable damping unit; 701. Second set of conjoined disc springs; 702. Sealing end cover; 7031. Inner cylinder body; 7032. Outer cylinder body; 704. Outer excitation coil; 705. Piston head; 706. End shield; 707. Guide frame; 708. Magnetorheological fluid; 709. Inner excitation coil; 710. Piston rod; 711. Helical spring; 712. Bottom cover; 8. Second load-bearing column. Specific implementation manners

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] The purpose of the present invention is to provide a ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping, which includes two parts: a quasi-zero stiffness structure and a variable stiffness and variable damping structure. It improves the existing quasi-zero stiffness vibration isolator, combines the tapered rubber spring with non-linear positive stiffness and the conjoined disc spring group with non-linear negative stiffness in parallel, broadening the effective vibration isolation frequency band range of the vibration isolator; introducing the conjoined disc spring group into the variable stiffness and variable damping structure, when the load changes, by changing the current in the inner and outer excitation coils, the damping force and dynamic stiffness of the vibration isolator can be adjusted to always be in the quasi-zero stiffness interval, solving the problem that the vibration isolation ability of the traditional quasi-zero stiffness vibration isolator decreases when facing variable loads; at the same time, the structure of this vibration isolator is compact and has a strong load-bearing capacity, and is more suitable for complex engineering environments.

[0025] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0026] As Figure 1As shown in the figure, this embodiment provides a super-low-frequency quasi-zero stiffness isolator based on variable stiffness and variable damping, which includes a first load-bearing column 1, a first pair of mating disc spring groups 3, a conical rubber spring 4, a spacer 5, a housing 6, a variable stiffness and variable damping unit 7, and a second load-bearing column 8. An upper cavity and a lower cavity are arranged inside the housing 6, and the lower end of the first load-bearing column 1 penetrates through the upper cavity and extends into the lower cavity. A conical rubber spring 4 is arranged between the outer side wall of the lower end of the first load-bearing column 1 and the inner side wall of the lower cavity. A spacer 5 is arranged between the inner bottom of the lower cavity and the conical rubber spring 4, and the spacer 5 is used to keep the stiffness of the conical rubber spring 4 in the non-linear range. The first pair of mating disc spring groups 3 is sleeved on the first load-bearing column 1 and is located inside the upper cavity. The first load-bearing column 1 is a hollow column, and a cavity is arranged axially in the middle of the first load-bearing column 1. The variable stiffness and variable damping unit 7 is arranged in the cavity, and the bottom of the variable stiffness and variable damping unit 7 is in contact with the spacer 5. The lower end of the second load-bearing column 8 is connected to the top of the variable stiffness and variable damping unit 7.

[0027] In this specific embodiment, an adjusting nut 2 is further arranged on the first load-bearing column 1. The adjusting nut 2 is located above the first pair of mating disc spring groups 3. The position of the adjusting nut 2 on the first load-bearing column 1 is adjusted according to the number of disc springs in the first pair of mating disc spring groups 3. When there is no load on the first load-bearing column 1, the disc springs are kept fixed and will not shake randomly, so that when there is a load on the first load-bearing column 1, the disc springs in the first pair of mating disc spring groups 3 can deform in time to cope with the load change.

[0028] The conical rubber spring 4 includes a shaft core 401, a rubber layer 402, a spacer sleeve 403, and an outer sleeve 404. The shaft core 401 is sleeved on the lower end of the first load-bearing column 1. The outer side of the outer sleeve 404 is in contact with the inner side wall of the lower cavity. At least one spacer sleeve 403 is arranged between the shaft center and the outer sleeve 404. A rubber layer 402 is respectively arranged between the spacer sleeve 403 and the shaft core 401, between the spacer sleeve 403 and the outer sleeve 404, and between adjacent spacer sleeves 403.

[0029] According to the approximate change range of the load, a suitable conical rubber spring 4 is determined and an opening treatment is carried out on it, so as to achieve different radial stiffnesses in the transverse and longitudinal directions. Since the stiffness of the conical rubber spring 4 is approximately linear at the beginning and then presents non-linearity, in order to utilize its non-linear characteristics to expand the load change range of the isolator, by placing spacers 5 with different thicknesses between the conical rubber spring 4 and the base of the housing 6, different pre-compression amounts can be achieved, and then the stiffness of the conical rubber spring 4 can be in the required non-linear range.

[0030] In a more specific embodiment, the outer wall of the lower end of the first load-bearing column 1 is a conical structure, the lower end of the conical structure is the end with a smaller diameter, and the upper end of the conical structure is the end with a larger diameter; a conical hole is provided inside the shaft core 401, the conical hole matches the conical structure, and the outside of the shaft core 401 is arranged parallel to the inside of the core shaft. The outer side walls of the outer sleeve 404 and the inner side wall of the lower cavity are both vertical walls, and the outer side wall of the outer sleeve 404 is in contact with the inner side wall of the lower cavity. The inner side wall of the outer sleeve 404 is a conical wall, the lower end of the conical wall is the end with a smaller inner diameter, and the upper end of the conical wall is the end with a larger inner diameter.

[0031] When the first load-bearing column 1 bears the load and moves downward, the load is transmitted obliquely downward through the conical structure and the conical hole, compressing the rubber layer 402 to absorb the load and realizing passive vibration isolation in the horizontal and vertical directions.

[0032] The variable stiffness and variable damping unit 7 includes a piston rod 710, an inner cylinder body 7031, and an outer cylinder body 7032 arranged in sequence from the inside out; an inner excitation coil 709 is arranged in the middle of the piston rod 710, and an outer excitation coil 704 is arranged on the outer wall of the inner cylinder body 7031; a magnetorheological fluid 708 is filled between the inner cylinder body 7031 and the outer cylinder body 7032; a piston head 705 is arranged in the middle of the outer wall of the inner cylinder body 7031, and the outer excitation coil 704 is arranged on the piston head 705; a second pair of conical disc springs 701 is arranged between the upper end of the piston rod 710 and the second load-bearing column 8, and a helical spring 711 is arranged between the lower end of the piston rod 710 and the cushion block 5. By adjusting the current in the inner excitation coil 709, the equivalent damping of the vibration isolator can be changed; by adjusting the current in the outer excitation coil 704, the equivalent stiffness of the vibration isolator can be changed, reducing the natural frequency of the system and realizing the suppression of ultra-low frequency vibration.

[0033] In a more specific embodiment, a sealing end cover 702 is arranged above the inner cylinder body 7031 and the outer cylinder body 7032, and the sealing end cover 702 is used to seal the upper ends of the inner cylinder body 7031 and the outer cylinder body 7032. A guide frame 707 is arranged above the sealing end cover 702, the second pair of conical disc springs 701 is arranged in the guide frame 707, and the upper end of the piston rod 710 passes through the guide frame 707 and is connected to the second pair of conical disc springs 701. End covers are arranged at the lower ends of the inner cylinder body 7031 and the outer cylinder body 7032, and the end covers are used to seal the lower ends of the inner cylinder body 7031 and the outer cylinder body 7032. A bottom cover 712 is arranged below the end cover, the helical spring 711 is arranged in the bottom cover 712, the lower end of the piston rod 710 is in contact with the inner bottom surface of the bottom cover 712, and the outer bottom surface of the bottom cover 712 is in contact with the cushion block 5.

[0034] An end cover 706 is arranged between the bottom of the inner cylinder body 7031 and the bottom cover 712, and the lower end of the piston rod 710 extends into the end cover 706.

[0035] The provision of the guide frame 707 and the bottom cover 712 makes the variable stiffness and variable damping unit 7 a modular structure, facilitating the overall transportation and installation of the variable stiffness and variable damping unit 7. At the same time, it can form a sealed protection for the second pair of conical disc spring groups 701 and the helical spring 711, preventing foreign objects from entering and affecting the normal operation of the second pair of conical disc spring groups 701 and the helical spring 711, and improving the overall vibration isolation performance of the variable stiffness and variable damping unit 7.

[0036] In the ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping of the present invention, the quasi-zero stiffness technology and the variable stiffness and variable damping technology are skillfully integrated together to achieve the complementary advantages of the two. The conical rubber spring is connected in parallel with the first pair of conical disc spring groups, where the conical rubber spring provides non-linear positive stiffness and the first pair of conical disc spring groups provides non-linear negative stiffness, making the entire vibration isolator have the quasi-zero stiffness characteristic. The non-linearity of the spring stiffness expands the vibration isolation range of the vibration isolator. For the variable stiffness and variable damping unit, the helical spring is connected in parallel with the external damper and then connected in series with the second pair of conical disc spring groups, and then connected in parallel with the internal damper. When the piston rod vibrates up and down, the magnetorheological fluid has both shear flow and pressure difference flow in the inner and outer cylinders of the shear valve type damper, and the output damping force is the sum of the damping forces generated in the shear mode and the valve mode. When adjusting the current magnitude in the inner and outer excitation coils, the viscosity of the magnetorheological fluid will be changed, thereby achieving the control of the damping force.

[0037] It should be noted that for those skilled in the art, obviously the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention, and any reference signs in the claims should not be regarded as limiting the claims involved.

[0038] In this specification, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping, characterized in that, It includes a first load-bearing column, a first pair of combined disc springs, a conical rubber spring, a cushion block, a housing, a variable stiffness and variable damping unit, and a second load-bearing column; an upper cavity and a lower cavity are arranged inside the housing, and the lower end of the first load-bearing column penetrates through the upper cavity and extends into the lower cavity; the conical rubber spring is arranged between the outer side wall of the lower end of the first load-bearing column and the inner side wall of the lower cavity; the cushion block is arranged between the inner bottom of the lower cavity and the conical rubber spring, and the cushion block is used to keep the stiffness of the conical rubber spring in the non-linear range; the first pair of combined disc springs is sleeved on the first load-bearing column and is located inside the upper cavity; the first load-bearing column is a hollow column, and a cavity is arranged axially in the middle of the first load-bearing column; the variable stiffness and variable damping unit is arranged in the cavity, and the bottom of the variable stiffness and variable damping unit is in contact with the cushion block; the lower end of the second load-bearing column is connected to the top of the variable stiffness and variable damping unit.

2. The ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping according to claim 1, characterized in that It further includes an adjusting nut, the adjusting nut is arranged on the first load-bearing column and is located above the first pair of combined disc spring set, and the position of the adjusting nut on the first load-bearing column is adjusted according to the number of disc springs in the first pair of combined disc spring set.

3. The ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping according to claim 1, characterized in that The conical rubber spring includes a shaft core, a rubber layer, a spacer sleeve and an outer sleeve; the shaft core is arranged at the lower end of the first load-bearing column; the outer side of the outer sleeve is in contact with the inner side wall of the lower cavity, at least one spacer sleeve is arranged between the shaft center and the outer sleeve, and a rubber layer is respectively arranged between the spacer sleeve and the shaft core, between the spacer sleeve and the outer sleeve, and between adjacent spacer sleeves.

4. The ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping according to claim 3, characterized in that, The shaft core is a conical structure, and a through hole vertically penetrating is arranged at the center of the core shaft, and the through hole is used to accommodate the variable stiffness and variable damping unit.

5. The ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping according to claim 3 or 4, characterized in that, The outer side wall of the outer sleeve and the inner side wall of the lower cavity are both vertical walls, and the outer side wall of the outer sleeve is in contact with the inner side wall of the lower cavity, the inner side wall of the outer sleeve is a conical wall, the lower end of the conical wall is the end with a smaller inner diameter, and the upper end of the conical wall is the end with a larger inner diameter.

6. The ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping according to claim 1, characterized in that The variable stiffness and variable damping unit includes a piston rod, an inner cylinder body and an outer cylinder body which are arranged in sequence from inside to outside; an inner excitation coil is arranged in the middle of the piston rod, and an outer excitation coil is arranged on the outer wall of the inner cylinder body; a magnetorheological fluid is filled between the inner cylinder body and the outer cylinder body; a piston head is arranged in the middle of the outer wall of the inner cylinder body, and an outer excitation coil is arranged on the piston head; a second pair of combined disc springs is arranged between the upper end of the piston rod and the second load-bearing column, and a helical spring is arranged between the lower end of the piston rod and the cushion block.

7. The ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping according to claim 6, characterized in that, A sealing end cover is arranged above the inner cylinder body and the outer cylinder body, and the sealing end cover is used to seal the upper ends of the inner cylinder body and the outer cylinder body.

8. The ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping according to claim 7, characterized in that, A guide frame is arranged above the sealing end cover, the second pair of combined disc springs is arranged in the guide frame, and the upper end of the piston rod penetrates through the guide frame and is connected to the second pair of combined disc springs.

9. The ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping according to claim 6, characterized in that, An end cover is arranged at the lower ends of the inner cylinder body and the outer cylinder body, and the end cover is used to seal the lower ends of the inner cylinder body and the outer cylinder body.

10. The ultra-low frequency quasi-zero stiffness vibration isolator based on variable stiffness and variable damping according to claim 9, characterized in that, A bottom cover is provided below the end cover, the coil spring is provided in the bottom cover, the lower end of the piston rod contacts the inner bottom surface of the bottom cover, and the outer bottom surface of the bottom cover contacts the cushion block.

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