A time-varying stiffness vibration isolator based on active control

Abstract

The application discloses a time-varying stiffness vibration isolator based on active control, which is supported as a whole by a base, and a PID controller actively controls a driving mechanism to drive a negative stiffness adjusting mechanism to generate corresponding adaptive negative stiffness according to the change of a vibration environment and actual demand, so that the stiffness of the vibration isolator can be adaptively adjusted, thereby realizing vibration isolation in multiple working conditions. In addition, the vibration isolator can also perform low-frequency vibration isolation and has the advantages of high static and low dynamic.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of vibration isolators, and particularly relates to a time-varying stiffness vibration isolator based on active control. BACKGROUND

[0002] In the field of aerospace, the aircraft is affected by the harsh environment, and unnecessary vibration often occurs, which not only affects the precision of the instrument, but also can cause damage to the structure of the aircraft, thereby causing disastrous consequences, so it is necessary to design an efficient vibration isolation device.

[0003] Now passive vibration isolation is widely used in various fields, and passive vibration isolation has the advantages of simple structure, reliable work, and no need for additional energy input, but passive vibration isolation also has the disadvantages of difficulty in low-frequency resonance suppression, and the parameters of passive vibration isolation devices are not easy to adjust.

[0004] Therefore, whether an active control type vibration isolator can be developed to solve the above problems has become a problem that people urgently need to solve. SUMMARY

[0005] In view of this, the present application provides a time-varying stiffness vibration isolator based on active control to solve the problems of difficulty in low-frequency resonance suppression and difficulty in adjusting the parameters of passive vibration isolation devices.

[0006] The technical scheme provided by the present application is a time-varying stiffness vibration isolator based on active control, which comprises a base, a driving mechanism, a negative stiffness adjusting mechanism, a positive stiffness mechanism, a fixed connecting piece, a vibration sensor and a PID controller.

[0007] The base comprises a base plate, a first support column and a second support column.

[0008] The first support column and the second support column are respectively arranged at two ends of the base plate, and the bottom surface of the first support column and the bottom surface of the second support column are fixedly connected with the upper surface of the base plate.

[0009] The driving mechanism comprises a door-shaped support frame, a piezoelectric driver and a pre-tightening device.

[0010] The door-shaped support frame is fixedly installed on the base plate and located between the first support column and the second support column.

[0011] The piezoelectric driver is installed above the door-shaped support frame.

[0012] The pre-tightening device is installed above the second support column, and the pre-tightening device is connected with one end of the piezoelectric driver.

[0013] The negative stiffness adjusting mechanism is fixedly connected with one end of the first supporting column and located above the door-shaped supporting frame, and the end located above the door-shaped supporting frame abuts against the other end of the piezoelectric driver, and the negative stiffness adjusting mechanism generates negative stiffness under the driving of the piezoelectric driver, and a through upper and lower mounting hole is arranged on the negative stiffness adjusting mechanism;

[0014] The positive stiffness mechanism is mounted on the substrate and located below the negative stiffness adjusting mechanism;

[0015] The lower end of the fixed connecting piece is mounted in the positive stiffness mechanism to vertically transmit positive stiffness, and the upper end of the fixed connecting piece passes through the mounting hole on the negative stiffness adjusting mechanism to be connected with the vibration isolation object;

[0016] The control end of the PID controller is connected with the control end of the piezoelectric driver, and the PID controller actively controls the action of the piezoelectric driver according to the change of the vibration environment and the actual demand to drive the negative stiffness adjusting mechanism to generate corresponding negative stiffness.

[0017] Preferably, the upper surface of the first supporting column is provided with an L-shaped step, the bottom surface of the end of the negative stiffness adjusting mechanism fixedly connected with the first supporting column is fixedly connected with the lower step in the L-shaped step, and the end surface abuts against the side wall of the upper step in the L-shaped step.

[0018] Further preferably, the negative stiffness adjusting mechanism is a buckling beam.

[0019] Further preferably, the negative stiffness adjusting mechanism comprises two elastic steel plates, two end fixed blocks and one middle fixed block.

[0020] The two elastic steel plates are arranged in an upper and lower interval to form an elastic steel plate group, and a through upper and lower mounting hole is arranged in the center of each elastic steel plate.

[0021] The two end fixed blocks are arranged at two ends of the elastic steel plate group respectively and located between the two elastic steel plates, and the upper and lower surfaces of each end fixed block are fixedly connected with the adjacent elastic steel plate respectively.

[0022] The middle fixed block is fixedly mounted in the center of the elastic steel plate group and located between the two elastic steel plates, a through upper and lower mounting hole is arranged on the middle fixed block, and the mounting hole on the middle fixed block is coaxially arranged with the mounting holes on the two elastic steel plates.

[0023] Further preferably, the positive stiffness mechanism comprises a shell, a cover, a pressing plate, a first spiral spring and a second spiral spring.

[0024] The upper end of the shell is open;

[0025] The cover is buckled at the open upper end of the shell and is screwed with the shell, and an installation space is formed between the cover and the shell, and a through hole is arranged on the top surface of the cover;

[0026] The first and second spiral springs are arranged in the installation space formed between the cover and the shell in a stacked manner;

[0027] The lower end of the fixed connecting piece is located between the first and second spiral springs.

[0028] Further preferably, the fixed connecting piece comprises a longitudinal threaded rod and a bottom base plate.

[0029] The bottom base plate is installed in the installation space formed between the cover and the shell, and the lower surface of the bottom base plate abuts against the second spiral spring, and the upper surface of the bottom base plate abuts against the first spiral spring.

[0030] The lower end of the longitudinal threaded rod is fixedly connected with the upper surface of the bottom base plate, and the upper end of the longitudinal threaded rod sequentially penetrates through the first spiral spring, the through hole on the cover and the installation hole in the negative stiffness adjusting mechanism, and is used for being connected with a vibration isolation object.

[0031] The active control based time-varying stiffness vibration isolator provided by the application takes a base as a whole support, and a PID controller actively controls a driving mechanism to drive a negative stiffness adjusting mechanism to generate corresponding adaptive negative stiffness according to changes in a vibration environment and actual requirements, and a fixed connecting piece is used to transmit and abut the positive stiffness of the positive stiffness mechanism and the negative stiffness of the negative stiffness adjusting mechanism, so as to achieve the purpose of vibration isolation.

[0032] The active control based time-varying stiffness vibration isolator provided by the application can realize real-time control of the driving mechanism by the PID controller, so that the stiffness of the vibration isolator can be adaptively adjusted, thereby realizing vibration isolation in multiple working conditions. In addition, the vibration isolator can also perform low-frequency vibration isolation and has the advantages of high static and low dynamic.

[0033] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the disclosure of the application. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings incorporated in the specification and constituting a part hereof illustrate embodiments consistent with the application and, together with the specification, serve to explain the principles of the application.

[0035] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or the prior art description will be briefly introduced. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0036] Figure 1 A structure schematic diagram of a time-varying stiffness vibration isolator based on active control provided for the disclosed embodiments of the present application;

[0037] Figure 2 A structure schematic diagram of a positive stiffness mechanism in a time-varying stiffness vibration isolator based on active control provided for the disclosed embodiments of the present application. DETAILED DESCRIPTION

[0038] The exemplary embodiments will be described in detail herein with reference to the drawings. Unless otherwise specified, the same numbers in different drawings indicate the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they only represent examples of devices consistent with some aspects of the present application, as detailed in the appended claims.

[0039] In order to solve the problems of low-frequency resonance suppression difficulty of the prior passive vibration isolation, and the difficulty of adjusting the parameters of the passive vibration isolation device, the present embodiment provides a time-varying stiffness vibration isolator based on active control, as shown in Figure 1The vibration isolator mainly comprises a base 1, a driving mechanism 2, a negative stiffness adjusting mechanism 3, a positive stiffness mechanism 4, a fixed connecting piece 5, a vibration sensor and a PID controller 6. The base 1 mainly comprises a base plate 11, a first supporting column 12 and a second supporting column 13. The first supporting column 12 and the second supporting column 13 are arranged at two ends of the base plate 11 respectively. The first supporting column 12 and the second supporting column 13 are arranged perpendicularly relative to the base plate 11. The bottom surface of the first supporting column 12 and the bottom surface of the second supporting column 13 are fixedly connected with the upper surface of the base plate 11. The driving mechanism 2 comprises a door-shaped supporting frame 21, a piezoelectric driver 22 and a pre-tightening device 23. The door-shaped supporting frame 21 is fixedly installed on the base plate 11 and located between the first supporting column 12 and the second supporting column 13, so as to facilitate the installation of the door-shaped supporting frame 21. A positioning block is arranged beside each of the two longitudinal side plates of the door-shaped supporting frame 21. The positioning block is fixedly connected with the base plate 11 through bolts. The two longitudinal side plates of the door-shaped supporting frame 21 are fixedly connected with the side walls adjacent to the positioning blocks through bolts. The piezoelectric driver 22 is installed above the door-shaped supporting frame 21. The pre-tightening device 23 is installed above the second supporting column 13. The pre-tightening device 23 is connected with one end of the piezoelectric driver 22. One end of the negative stiffness adjusting mechanism 3 is fixedly connected with the first supporting column 12. The other end of the negative stiffness adjusting mechanism 3 is located above the door-shaped supporting frame 21 and abuts against the other end of the piezoelectric driver 22. Under the driving of the piezoelectric driver 22, the negative stiffness adjusting mechanism 3 generates negative stiffness. An installation hole penetrating the upper and lower portions is arranged on the negative stiffness adjusting mechanism 3. The positive stiffness mechanism 4 is installed on the base plate 11 and located below the negative stiffness adjusting mechanism 3. The lower end of the fixed connecting piece 5 is installed in the positive stiffness mechanism 4. The vertical direction transmits positive stiffness. The upper end of the fixed connecting piece 5 penetrates the installation hole on the negative stiffness adjusting mechanism 3 and is used for being connected with a vibration isolation object. The control end of the PID controller 6 is connected with the control end of the piezoelectric driver 22. The PID controller 6 actively controls the piezoelectric driver 22 to act according to the changes of the vibration environment and actual requirements, so as to drive the negative stiffness adjusting mechanism 3 to generate corresponding negative stiffness.

[0040] The vibration isolator in the above embodiment takes the base as the overall support. The PID controller actively controls the driving mechanism to drive the negative stiffness adjusting mechanism to generate corresponding adaptive negative stiffness according to the changes of the vibration environment and actual requirements. The positive stiffness of the positive stiffness mechanism and the negative stiffness of the negative stiffness adjusting mechanism are transmitted by the fixed connecting piece respectively, so as to achieve the purpose of vibration isolation.

[0041] In order to realize the stable limiting of one end of the negative stiffness adjusting mechanism 3, the driving mechanism 2 drives the negative stiffness adjusting mechanism 3 to adaptively adjust the negative stiffness. Referring to Figure 1The upper surface of the first support column 12 is provided with an L-shaped step, the bottom surface of the end part fixedly connected with the first support column 12 in the negative stiffness adjusting mechanism 3 is fixedly connected with the lower step in the L-shaped step, and the end surface is in abutment with the sidewall of the upper step in the L-shaped step.

[0042] The negative stiffness adjusting mechanism 3 is a buckling beam, and the adaptive adjustment of the negative stiffness is realized through the buckling movement of the buckling beam, as shown in Figure 1 The negative stiffness adjusting mechanism 3 mainly comprises two elastic steel plates 31, two end fixed blocks 32 and one middle fixed block 33. The two elastic steel plates 31 are arranged in an upper and lower spaced manner to form an elastic steel plate group. The central part of each elastic steel plate 31 is provided with a through upper and lower mounting hole. The two end fixed blocks 32 are arranged at the two ends of the elastic steel plate group and are located between the two elastic steel plates 31. The upper and lower surfaces of each end fixed block 32 are fixedly connected with the adjacent elastic steel plate 31. The middle fixed block 33 is fixedly installed at the center of the elastic steel plate group and is located between the two elastic steel plates 31. The middle fixed block 33 is provided with a through upper and lower mounting hole, and the mounting hole in the middle fixed block 33 is coaxially arranged with the mounting holes in the two elastic steel plates 31.

[0043] The buckling beam adopts two elastic steel plates 31 to form an elastic steel plate group, and the two elastic steel plates are assembled through two end fixed blocks and one middle fixed block, so that the structure is simple and the assembly is convenient.

[0044] As shown in Figure 2 , the positive stiffness mechanism 4 comprises a shell 41, a cover 42, a pressing plate 43, a first spiral spring 44 and a second spiral spring 45. The upper end of the shell 41 is open. The cover 42 is buckled at the upper end opening of the shell 41 and is screwed with the shell 41. An installation space is formed between the cover 42 and the shell 41. The cover 42 is provided with a through hole penetrating through the upper and lower surfaces. The first spiral spring 44 and the second spiral spring 45 are stacked and arranged in the installation space formed between the cover 42 and the shell 41. The lower end of the fixed connecting piece 5 is located between the first spiral spring 44 and the second spiral spring 45, and the positive stiffness is generated through the first spiral spring 44 and the second spiral spring 45.

[0045] As shown in Figure 1 , Figure 2 The fixed connecting piece 5 comprises a longitudinal threaded rod 51 and a bottom base plate 52. The bottom base plate 52 is installed in the installation space formed between the cover 42 and the shell 41. The lower surface of the bottom base plate 52 is in abutment with the second spiral spring 45, and the upper surface of the bottom base plate 52 is in abutment with the first spiral spring 44. The lower end of the longitudinal threaded rod 51 is fixedly connected with the upper surface of the bottom base plate 52. The upper end of the longitudinal threaded rod 51 penetrates through the first spiral spring 44, the through hole in the cover 42 and the mounting hole in the negative stiffness adjusting mechanism 3 in sequence, and is used for being connected with the vibration isolation object.

[0046] In the above scheme, the vibration control equation of the whole vibration isolator can be written as:

[0047] ;

[0048] wherein, k 1 is the positive stiffness, k 2 is the negative stiffness when the buckling beam buckles, k T is the linear stiffness of the piezoelectric driver, k T * U is the output displacement of the piezoelectric driver, L is the length of the buckling beam, U is the output voltage of the piezoelectric driver, and PID is the active control.

[0049] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0050] It is to be understood that the application is not limited to the embodiments described above, and various modifications and changes can be made without departing from the scope of the present application. The scope of the application is limited only by the claims that follow.

Claims

1. A time-varying stiffness vibration isolator based on active control, characterized in that, include: Base (1), drive mechanism (2), negative stiffness adjustment mechanism (3), positive stiffness mechanism (4), fixed connector (5), and PID controller (6); The base (1) includes: a base plate (11), a first support column (12) and a second support column (13); The first support column (12) and the second support column (13) are respectively disposed at both ends of the substrate (11), and the bottom surface of the first support column (12) and the bottom surface of the second support column (13) are fixedly connected to the upper surface of the substrate (11). The drive mechanism (2) includes: a portal support frame (21), a piezoelectric actuator (22), and a pre-tightening device (23); A portal frame (21) is fixedly installed on the base plate (11) and located between the first support column (12) and the second support column (13); The piezoelectric actuator (22) is mounted above the portal frame (21); The pre-tightening device (23) is installed above the second support column (13), and the pre-tightening device (23) is connected to one end of the piezoelectric actuator (22); One end of the negative stiffness adjustment mechanism (3) is fixedly connected to the first support column (12), and the other end is located above the portal support frame (21). The end located above the portal support frame (21) abuts against the other end of the piezoelectric actuator (22). Under the drive of the piezoelectric actuator (22), the negative stiffness adjustment mechanism (3) generates negative stiffness. A through mounting hole is provided on the negative stiffness adjustment mechanism (3). The positive stiffness mechanism (4) is mounted on the base plate (11) and located below the negative stiffness adjustment mechanism (3); The lower end of the fixed connector (5) is installed in the positive stiffness mechanism (4) to transmit positive stiffness in the vertical direction. The upper end of the fixed connector (5) passes through the mounting hole on the negative stiffness adjustment mechanism (3) for connection with the vibration isolation object. The control terminal of the PID controller (6) is connected to the control terminal of the piezoelectric actuator (22). The PID controller (6) actively controls the piezoelectric actuator (22) to operate according to the changes in the vibration environment and actual needs, thereby driving the negative stiffness adjustment mechanism (3) to generate the corresponding negative stiffness. The negative stiffness adjustment mechanism (3) includes: two elastic steel plates (31), two end fixing blocks (32) and one intermediate fixing block (33); Two elastic steel plates (31) are arranged at intervals above and below to form an elastic steel plate group, and a through mounting hole is provided in the center of each elastic steel plate (31). The two end fixing blocks (32) are respectively disposed at both ends of the elastic steel plate group, and are located between the two elastic steel plates (31). The upper and lower surfaces of each end fixing block (32) are respectively fixedly connected to the adjacent elastic steel plate (31). The intermediate fixing block (33) is fixedly installed in the center of the elastic steel plate group, located between the two elastic steel plates (31). The intermediate fixing block (33) is provided with mounting holes that pass through the upper and lower ends, and the mounting holes on the intermediate fixing block (33) are coaxially arranged with the mounting holes on the two elastic steel plates (31). The positive stiffness mechanism (4) includes: a housing (41), a cover (42), a pressure plate (43), a first helical spring (44), and a second helical spring (45). The upper end of the shell (41) is open; The cover (42) is fastened to the upper opening of the housing (41) and threadedly engaged with the housing (41). An installation space is formed between the cover (42) and the housing (41). A through hole is provided on the top surface of the cover (42). The first helical spring (44) and the second helical spring (45) are stacked and disposed between the cover (42) and the housing (41) to form an installation space; The lower end of the fixed connector (5) is located between the first helical spring (44) and the second helical spring (45); The fixed connector (5) includes: a longitudinal threaded rod (51) and a bottom base plate (52); The bottom substrate (52) is installed between the cover (42) and the housing (41) to form an installation space. The lower surface of the bottom substrate (52) abuts against the second helical spring (45), and the upper surface of the bottom substrate (52) abuts against the first helical spring (44). The lower end of the longitudinal threaded rod (51) is fixedly connected to the upper surface of the bottom substrate (52), and the upper end of the longitudinal threaded rod (51) passes through the through hole on the first helical spring (44), the cover (42) and the mounting hole in the negative stiffness adjustment mechanism (3) in sequence, for connection with the vibration isolation object.

2. The time-varying stiffness vibration isolator based on active control according to claim 1, characterized in that, The upper surface of the first support column (12) is provided with an L-shaped step. The bottom surface of the end of the negative stiffness adjustment mechanism (3) that is fixedly connected to the first support column (12) is fixedly connected to the lower step of the L-shaped step, and the end face of the end abuts against the side wall of the upper step of the L-shaped step.

3. The time-varying stiffness vibration isolator based on active control according to claim 1, characterized in that, The negative stiffness adjustment mechanism (3) is a buckling beam.

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