A quasi-zero stiffness vibration isolator

Abstract

The invention discloses a quasi-zero stiffness vibration isolator, which overcomes the problem that the current linear vibration isolation system cannot reduce the initial vibration isolation frequency while maintaining the necessary bearing capacity. The device comprises a negative stiffness mechanism and a positive stiffness mechanism; the negative stiffness mechanism comprises two sets of fixed joint structures, a support structure, a leaf spring, a base plate, four linear bearings, two bearing connection blocks, a stage and a neck flange, four short pins and five No. 2 short shafts; the two sets of fixed joint structures are installed between the two sides of the vertical axis and the two horizontal axes in the support structure, one end of the short rod of the two sets of fixed joint structures is connected to the two horizontal axes through the linear bearings in the bearing connection blocks, and the lower ends of the long rods of the two sets of fixed joint structures and the base plate which is sleeved on the lower end of the vertical axis and located above the fixed block are connected by short pins; the stacked neck flanges, leaf springs and the stage are bolted, and the neck flange is threadedly connected to the top end of the vertical axis; the positive stiffness mechanism is sleeved on the vertical axis, the top end of the positive stiffness mechanism contacts the bottom ends of the four cross connectors, and the bottom end of the positive stiffness mechanism is installed on the base plate.

Description

Technical Field

[0001] The invention relates to a device belonging to the field of low-frequency vibration isolation, and more specifically, to a nonlinear quasi-zero stiffness vibration isolator with positive and negative stiffness connected in parallel. Background Art

[0002] In actual engineering, some high-precision mechanical equipment needs to isolate the vibration transmitted from the foundation to the equipment during use to ensure the necessary accuracy of the equipment. In order to isolate this vibration, the traditional vibration isolation method is to install springs and rubber pads (damping) at the connection between the equipment and the supporting structure for linear vibration isolation. According to vibration theory, the starting vibration isolation frequency of the linear vibration isolation method is the natural frequency of the vibration isolation method. times. Therefore, to achieve vibration isolation in a lower frequency domain, the only way is to reduce the natural frequency of the vibration isolation system. For a linear vibration isolation system, this means reducing its stiffness. However, low stiffness will cause the system to produce a large static displacement. The quasi-zero stiffness isolator uses positive stiffness and negative stiffness mechanisms in parallel to achieve low dynamic stiffness of the overall vibration isolation system. Then, according to the natural frequency expression of the vibration isolation system, The reduced stiffness makes the vibration isolation system have a lower natural frequency. Compared with the linear vibration isolation system with the same static load-bearing capacity, the quasi-zero stiffness vibration isolator also has an isolation effect on vibrations in the lower frequency domain, while maintaining a high static stiffness and being able to carry a certain weight of load. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the problem that the linear vibration isolation system in the prior art cannot reduce the initial vibration isolation frequency while maintaining the necessary bearing capacity, and provide a quasi-zero stiffness vibration isolator.

[0004] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions: the quasi-zero stiffness isolator comprises a negative stiffness mechanism and a positive stiffness mechanism;

[0005] The negative stiffness mechanism comprises two sets of fixed joint structures with the same structure, a support structure, a leaf spring, a base plate, four linear bearings with the same structure, two bearing connection blocks with the same structure, a stage, a flange with a neck, four short pins with the same structure and five short shafts No. 2 with the same structure;

[0006] The fixed joint structure also includes 3 'I'-shaped joints with the same structure, 3 'Y'-shaped joints with the same structure, 2 round tube clamps with the same structure, a short shaft No. 1 and a fixed rod; the two ends of the long rod are threadedly connected with the two 'I'-shaped joints with the same structure; the two ends of the short rod are threadedly connected with the 'I'-shaped joint and the 'Y'-shaped joint; the two ends of the fixed rod are threadedly connected with the two 'Y'-shaped joints with the same structure; one end of the long rod and one end of the short rod on which the 'Y'-shaped joint is installed are connected by a short shaft No. 1, and two bearings with the same structure are sleeved on the two ends of the short shaft No. 1 extending out of the 'Y'-shaped light hole on the 'Y'-shaped joint; the two ends of the fixed rod are connected by short pins through two 'Y'-shaped joints with the two ends of the round tube clamps with the same structure sleeved on the long rod and the short rod;

[0007] The support structure also includes 4 'I'-shaped joints with the same structure, 9 cross connectors with the same structure and two identical fixed shafts; 3 No. 2 short shafts with the same structure are fixed in parallel to the left and right ends and the middle position of two horizontal shafts with the same structure through 2 vertical cross connectors with the same structure; to be more specific: the two ends of the No. 2 short shaft are respectively vertically connected to the two horizontal shafts with the same structure through cross connectors, wherein the No. 2 short shaft fixed in the middle position of the two horizontal shafts with the same structure is vertically cross-connected with the vertical shaft through a horizontal cross connector, so that the two horizontal shafts with the same structure are fixed in parallel and aligned on the front and rear sides of the vertical shaft and vertically cross in space; the two cross connectors fixed on the right side of the vertical shaft in the middle position of the two horizontal shafts with the same structure are used to form a bottom plane with the two cross connectors fixed on the left side of the vertical shaft in the middle position of the two horizontal shafts with the same structure, and the bottom plane is in contact with and connected to the No. 1 spring base;

[0008] One end of the 'I'-shaped joint of two fixed shafts with the same structure is connected to both ends of the fixed block by two short pins with the same structure, and the other end of the 'I'-shaped joint of two fixed shafts with the same structure is connected to two symmetrical cross connectors with the same structure installed at both ends of the two horizontal shafts with the same structure by two short shafts No. 2 with the same structure, the upper end of the vertical shaft is threadedly connected to the neck flange, and the lower end of the vertical shaft is threadedly connected to the fixed block;

[0009] The positive stiffness mechanism comprises a spring, a No. 1 spring base and a No. 2 spring base;

[0010] The two sets of fixed joint structures with the same structure are symmetrically installed on the left and right sides of the vertical axis in the supporting structure and are located between the two horizontal axes with the same structure in the supporting structure. One end of the short rod in the two sets of fixed joint structures with the same structure is connected to the two horizontal axes with the same structure through a linear bearing installed in the bearing connection block. The lower ends of the long rods in the two sets of fixed joint structures with the same structure are connected to the bottom plate which is sleeved on the lower end of the vertical axis and located above the fixed block in the supporting structure by a short pin; the stacked neck flange and the leaf spring are connected to the stage by bolts from bottom to top, the neck flange is threadedly connected to the top end of the vertical axis, and the bottom end surface of the leaf spring is contacted and connected to the four bearings with the same structure in the two sets of fixed joint structures with the same structure; the positive stiffness mechanism is sleeved on the vertical axis, the top end of the positive stiffness mechanism is contacted and connected to the bottom end surface of the four cross connectors with the same structure and placed in the middle of the two horizontal axes with the same structure through the No. 1 spring base, the bottom end of the positive stiffness mechanism is installed on the bottom plate through the No. 2 spring base, and the spring is installed between the No. 1 spring base and the No. 2 spring base.

[0011] The cross connector described in the technical solution is a rectangular structural member, and optical through holes with the same structure are arranged at both ends of the cross connector. The rotation axes of the two optical through holes with the same structure are vertically crossed in space, and the rotation axes of the two optical through holes with the same structure are equidistant from the left and right end faces. A gap of equal thickness is arranged along the radial direction of the two optical through holes with the same structure and perpendicular to the left and right end faces. The gap is connected with the two optical through holes with the same structure. A threaded hole is arranged on one side wall of the two side walls of the gap, and a light hole for mounting bolts is arranged on the other side wall of the two side walls of the gap. Bolts are inserted into the optical through holes on one side wall and then connected to the threaded holes on the other side wall.

[0012] The fixed block described in the technical solution is a rectangular structural member, and 'U'-shaped grooves with the same structure are symmetrically arranged at both ends of the fixed block, and light-through holes with colinear rotation axes are symmetrically arranged on the groove walls of the two 'U'-shaped grooves with the same structure. A central threaded hole that cooperates with the threaded end of the vertical axis is arranged at the center of the fixed block, and the rotation axis of the central threaded hole and the rotation axis of the light-through holes arranged on the groove walls of the 'U'-shaped grooves at both ends of the fixed block are spatially intersected and perpendicular.

[0013] The base plate described in the technical solution includes a base and four lugs with the same structure; the base is a rectangular plate, a two-section stepped through hole is arranged at the center of the base, the diameter of the small diameter section light hole is equal to the diameter of the vertical axis, and the two are slidingly matched, the large diameter section light hole is equal to the outer diameter of the No. 2 spring base, and four light holes are symmetrically arranged around the two-section stepped through hole, and the center line of the four light holes is a quadrilateral with the same symmetry axis as the base; the lug is a rectangular plate, one end of the lug is provided with a light hole, and the rotation axis of the light hole is far away from the other end of the lug, that is, the base installed, and four rectangular lugs with the same structure are vertically installed on the base, and the four rectangular lugs with the same structure are arranged parallel and symmetrically relative to the longitudinal and transverse symmetry lines of the base.

[0014] The bearing connecting block described in the technical solution is a U-shaped structural member, a groove is provided at the upper end of the bearing connecting block, groove wall light through holes with colinear rotation axes are provided on the two groove walls, and two groove bottom wall light through holes with the same structure that are parallel and symmetrical to the rotation axis are provided on the groove bottom wall of the bearing connecting block. The diameter of the groove bottom wall light through hole is equal to the outer diameter of the annular body in the flanged linear bearing, and threaded connection holes are respectively provided above and below the two groove bottom wall light through holes; the two threaded connection holes are aligned with the two light through holes on the flange seat in the flanged linear bearing.

[0015] The spring base No. 1 described in the technical solution includes a bottom disk No. 1 and a hollow cylinder No. 1; a light through hole No. 1 is arranged at the center of the bottom disk No. 1, and the diameter of the light through hole No. 1 is equal to the diameter of the vertical axis. The two are matched, and the bottom surface of the bottom disk No. 1 is in contact with the plane formed by the bottom end surfaces of four cross connectors with the same structure fixed in the middle of two horizontal axes with the same structure; the outer diameter of the hollow cylinder No. 1 is equal to the inner diameter of the spring; one end of the hollow cylinder No. 1 is connected to the upper surface of the bottom disk No. 1, and the rotation axis of the hollow cylinder No. 1, the light through hole No. 1 and the bottom disk No. 1 are collinear.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The quasi-zero stiffness vibration isolator described in the present invention can achieve the requirements of high static stiffness and low dynamic stiffness, and broaden the vibration isolation frequency range while maintaining the load-bearing capacity;

[0018] 2. The quasi-zero stiffness isolator described in the present invention has a wider quasi-zero stiffness range than other quasi-zero stiffness isolators, and also has a better isolation effect on low-frequency and large-amplitude vibrations. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings:

[0020] Figure 1Axonometric projection view of the structure of a quasi-zero stiffness vibration isolator according to the present invention

[0021] Figure 2 Axonometric projection view of the fixed joint structure used in a quasi-zero stiffness vibration isolator according to the present invention

[0022] Figure 3 It is an axonometric projection view of the supporting structure structure used in a quasi-zero stiffness vibration isolator described in the present invention;

[0023] Figure 4 It is an axonometric projection view of the bottom plate structure used in the quasi-zero stiffness vibration isolator described in the present invention;

[0024] Figure 5 It is an axonometric projection view of the bearing connection block structure used in a quasi-zero stiffness vibration isolator described in the present invention;

[0025] Figure 6 It is an axonometric projection view of the leaf spring structure used in the quasi-zero stiffness vibration isolator described in the present invention;

[0026] Figure 7 It is an axonometric projection view of the structure of the No. 2 spring support seat used in the quasi-zero stiffness vibration isolator described in the present invention;

[0027] Figure 8 It is an axonometric projection view of a neck flange structure used in a quasi-zero stiffness isolator according to the present invention;

[0028] Fig. 9 It is an axonometric projection view of the structure of the No. 1 spring support seat used in the quasi-zero stiffness vibration isolator described in the present invention;

[0029] Fig.10 It is an axonometric projection view of the structure of a flanged linear bearing used in a quasi-zero stiffness vibration isolator described in the present invention;

[0030] Fig.11 It is an axonometric projection view of the stage structure used in the quasi-zero stiffness vibration isolator described in the present invention;

[0031] Fig.12 It is an axonometric projection view of the 'Y'-shaped joint structure used in a quasi-zero stiffness vibration isolator described in the present invention;

[0032] Fig.13 It is an axonometric projection view of the 'I'-shaped joint structure used in a quasi-zero stiffness vibration isolator described in the present invention;

[0033] Fig.14It is an axonometric projection view of a circular tube clamp structure used in a quasi-zero stiffness vibration isolator according to the present invention;

[0034] Fig.15 It is an axonometric projection view of a cross connector structure used in a quasi-zero stiffness vibration isolator according to the present invention;

[0035] Fig.16 It is an axonometric projection view of the fixed block structure used in the quasi-zero stiffness vibration isolator described in the present invention;

[0036] Fig.17 It is a static characteristic curve of a quasi-zero stiffness vibration isolator described in the present invention;

[0037] In the figure: 1. fixed joint structure, 2. supporting structure, 3. leaf spring, 4. bottom plate, 5. linear bearing with flange, 6. bearing connecting block, 7. stage, 8. flange with neck, 9. spring, 101. spring base No. 1, 102. spring base No. 2, 11. 'I' type joint, 12. 'Y' type joint, 13. round tube clamp, 14. long rod, 15. short rod, 16. short shaft No. 1, 17. rolling bearing, 18. fixed rod, 19. cross connector, 20. fixed block, 21. short shaft No. 2, 22. short pin, 23. vertical axis, 24. horizontal axis, 25. fixed axis. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with the accompanying drawings:

[0039] The quasi-zero stiffness vibration isolator described in the present invention comprises a negative stiffness mechanism and a positive stiffness mechanism.

[0040] 1. See Figure 1 The negative stiffness mechanism includes two sets of fixed joint structures 1 with the same structure, a supporting structure 2, a leaf spring 3, a base plate 4, four linear bearings 5 ​​with the same structure, two bearing connecting blocks 6 with the same structure, a stage 7 and a neck flange 8, four short pins 22 with the same structure and five short shafts 21 with the same structure.

[0041] See also Figure 2 The fixed joint structure 1 includes three 'I'-shaped joints 11 with the same structure, three 'Y'-shaped joints 12 with the same structure, two round pipe clamps 13 with the same structure, a long rod 14, a short rod 15, a first short shaft 16, two bearings 17 with the same structure and a fixed rod 18;

[0042] The 'I'-type joint 11 is a standard part of the SC series cylinder joint, which is a cylindrical structural part as a whole. One end of the 'I'-type joint 11 is parallel to the axis and symmetrically provided with two countersunk planes, an 'I'-type light through hole is provided perpendicular to the countersunk plane, and an 'I'-type threaded blind hole is provided on the longitudinal rotation axis of the other end of the 'I'-type joint 11.

[0043] The 'Y'-shaped joint 12 is a standard part of the SC series cylinder joint. One end of the 'Y'-shaped joint 12 is symmetrically provided with two parallel clips, a 'Y'-shaped optical through hole is provided perpendicular to the two clips and passes through the two clips, and a 'Y'-shaped threaded blind hole is provided on the longitudinal rotation axis at the other end of the 'Y'-shaped joint 12.

[0044] A tube clamp light through hole is provided in the middle of the round tube clamp 13, and a gap of equal thickness for clamping that is connected to the tube clamp light through hole is provided on the left end protrusion along the radial direction of the tube clamp light through hole. The right end head is a sheet-like plate structure, and a right end light through hole is provided vertically through its surface, and a left end threaded through hole is provided at the center of the left end protrusion, the rotation axis of which intersects the rotation axis space of the tube clamp light through hole in the middle of the round tube clamp 13.

[0045] The long rod 14 is a cylindrical straight rod structure, and external threads are arranged at both ends of the long rod 14. The long rod 14 is connected to two 'I'-shaped joints 11 of the same structure through the external threads at both ends;

[0046] The short rod 15 is a cylindrical straight rod structure, and both ends of the short rod 15 are provided with external threads. The short rod 15 is connected to the 'Y'-shaped joint 12 through the external threads at both ends and the 'I'-shaped joint 11;

[0047] The No. 1 short shaft 16 is a cylindrical straight rod-type three-section stepped shaft, the first and third sections of the shaft at both ends have the same diameter and length, and are smaller than the diameter of the second section of the shaft in the middle, and two rolling bearings 17 are respectively provided on the first and third sections of the shaft;

[0048] The bearing 17 is a 6000 series deep groove ball bearing;

[0049] The fixing rod 18 is a cylindrical straight rod-like structural member, and both ends of the fixing rod 18 are provided with external threads, and the external threads at both ends of the fixing rod 18 are connected to two 'Y'-shaped joints 12;

[0050] One end of the short rod 15 is connected to the 'I'-shaped joint 11 through a thread, and the other end of the short rod 15 is connected to the 'Y'-shaped joint 12 through a thread; one end of the long rod 14 is connected to the second 'I'-shaped joint 11 through a thread, and the other end of the long rod 14 is connected to the third 'I'-shaped joint 11 through a thread; the No. 1 short shaft 16 is simultaneously inserted into the light holes on the I'-shaped joint 11 connected to the other end of the long rod 14 and the 'Y'-shaped joint 12 connected to the other end of the short rod 15, wherein the end of the 'I'-shaped joint 11 connected to the end of the long rod 14 is placed in the middle of the end of the 'Y'-shaped joint 12 connected to the end of the short rod 15, and the long rod 14 is rotatably connected to the other end of the short rod 15, and two bearings 17 of the same structure are sleeved on the two ends of the No. 1 short shaft 16 extending out of the Y'-shaped light hole on the 'Y'-shaped joint 12;

[0051] The two ends of the fixing rod 18 and the second Y'-shaped joint 12 are threadedly connected with the third Y'-shaped joint 12. One end of the Y'-shaped joint 12 at both ends of the fixing rod 18 is connected through two short pins 22 with the same structure and one end of two round tube clamps 13 with the same structure. That is, one end of the two round tube clamps 13 with the same structure is placed in the middle of one end of the two 'Y'-shaped joints 12 with the same structure. The two short pins 22 with the same structure are connected to the fixing rod 18. 22 Insert two pairs of round tube clamps 13 into the 'I'-shaped light holes and the Y'-shaped light holes on the 'Y'-shaped joint 12. The other ends of the two round tube clamps 13 with the same structure are sleeved in the middle of the long rod 14 and the short rod 15 and are clamped and fixed with bolts.

[0052] See also Figure 3 The support structure 2 includes 9 cross connectors 19 with the same structure, a fixing block 20, a vertical shaft 23, two horizontal shafts 24 with the same structure, two fixing shafts 25 with the same structure and 4 'I'-shaped joints 11 with the same structure.

[0053] See also Fig.15 The cross connector 19 is a rectangular parallelepiped structural member, with light through holes at both ends of the cross connector 19. The rotation axes of the two light through holes with the same structure are vertically crossed in space, and the rotation axes of the two light through holes with the same structure are equidistant from the left and right end faces. A 2mm thick gap is provided along the radial direction of the two light through holes with the same structure and perpendicular to the left and right end faces. The gap is connected to the two light through holes with the same structure. A threaded hole is provided on one side wall of the gap, and a light hole is provided on the other side wall of the gap. Bolts are inserted into the light through holes on one side wall and then connected to the threaded holes on the other side wall to realize the clamping function of the cross connector 19.

[0054] See also Fig.16The fixed block 20 is a rectangular parallelepiped structural member, and symmetrically arranged U-shaped grooves of the same structure are arranged at both ends of the fixed block 20. Light holes with colinear rotation axes are arranged on the two groove walls of the U-shaped groove. A central threaded hole that cooperates with the end of the vertical shaft 23 with threads is arranged at the center of the fixed block 20. The rotation axis of the central threaded hole and the rotation axis of the light holes arranged on the groove walls of the U-shaped grooves at both ends of the fixed block 20 are spatially crossed and perpendicular.

[0055] The No. 2 short axis 21 is a cylinder with equal diameter;

[0056] The short pin 22 is a cylinder of equal diameter;

[0057] The vertical shaft 23 is a cylindrical straight rod structure, and threads are respectively provided at both ends of the vertical shaft 23 .

[0058] The horizontal axis 24 is a cylindrical straight rod structure;

[0059] The fixed shaft 25 is a cylindrical straight rod-like structural member. External threads are arranged at both ends of the fixed shaft 25 . The two ends of the fixed shaft 25 are connected to two 'I'-shaped joints 11 through threads.

[0060] The three No. 2 short shafts 21 with the same structure are respectively fixed in parallel to the left and right ends and the middle position of the two horizontal shafts 24 with the same structure through two vertical cross connectors 19 with the same structure; to be more precise: the two ends of the short shaft 21 are respectively connected vertically to the two horizontal shafts 24 with the same structure through the cross connectors 19. The No. 2 short shaft 21 fixed in the middle position of the two horizontal shafts 24 with the same structure is vertically crossed with the vertical shaft 23 through a horizontal cross connector 19, so that the two horizontal shafts 24 with the same structure are fixed in parallel and aligned to the front and rear sides of the vertical shaft 23 and vertically cross in space; two cross connectors 19 are fixed on the right side of the vertical shaft 23 in the middle position of the two horizontal shafts 24 with the same structure to form a bottom plane with the two cross connectors 19 fixed on the left side of the vertical shaft 23 in the middle position of the two horizontal shafts 24 with the same structure, and the bottom plane is used to support the No. 1 spring base 101.

[0061] The two short pins 22 with the same structure are simultaneously inserted into the 'I'-shaped optical through hole on the 'I'-shaped joint 11 connected to one end of the two fixed shafts 25 with the same structure and the optical through holes at both ends of the fixed block 20. One end of the 'I'-shaped joint 11 is located in the 'U'-shaped groove at both ends of the fixed block 20. The other ends of the two fixed shafts 25 with the same structure are connected with the 'I'-shaped joint 11. The I'-shaped joint 11 is installed in the middle of the short shaft 21 connected by the cross connector 19 at both ends of the two horizontal shafts 24 with the same structure through the 'I'-shaped optical through hole thereon, that is, the end of the 'I'-shaped joint 11 at the other end of the two fixed shafts 25 with the same structure is placed between the cross connectors 19 at both ends of the two horizontal shafts 24 with the same structure.

[0062] See also Figure 6 The leaf spring 3 is a rectangular thin plate structural member, and four leaf spring light through holes with the same structure are arranged at the center of the leaf spring 3. The four leaf spring light through holes with the same structure are symmetrically arranged relative to the longitudinal and transverse symmetry axes of the leaf spring 3;

[0063] See also Figure 4 , the bottom plate 4 includes a base and four lugs with the same structure;

[0064] The base is a rectangular plate, and a two-stage stepped through hole is set at the center of the base. The diameter of the small diameter section of the light through hole is equal to the diameter of the vertical axis 23, and the two are slidingly matched. The large diameter section of the light hole is equal to the outer diameter of the second spring base 102. Four light through holes are symmetrically arranged around the two-stage stepped through hole, and the center line of the four light through holes is a quadrilateral with the same symmetry axis as the base.

[0065] The lug is a rectangular plate, and a light through hole is provided at one end of the lug. The rotation axis of the light through hole is far away from the other end of the lug, that is, the base on which it is installed. In the embodiment, the distance between the axis of the light hole and the upper surface of the rectangular base is 22 mm. Four rectangular lugs with the same structure are vertically installed on the base, and the four rectangular lugs with the same structure are arranged symmetrically relative to the longitudinal and transverse symmetry lines of the base; one end of the 'I'-shaped joint 11 connected to one end of the long rod 14 in the fixed joint structure 1 is installed between two front-to-back symmetrical lugs on one side of the base plate 4, and a short pin 22 is used to connect the 'I'-shaped joint 11 connected to one end of the long rod 14 in the fixed joint structure 1 with the two front-to-back symmetrical lugs on one side of the base plate 4.

[0066] See also Figure 1 and Fig.10The flanged linear bearing 5 comprises a circular ring body and a flange seat. The inner diameter of the circular ring body is equal to the diameter of the horizontal axis 24 in the support structure 2, and the outer diameter is equal to the inner diameter of the bottom wall light-through hole on the bearing connecting block 6; the long strip of flange seat is symmetrically provided with light-through holes at both ends along the longitudinal direction, and the distance between the axes of the two light-through holes is equal to the distance between the axes of the two threaded holes on the bearing connecting block 6. One end of the circular ring body is connected to a large end face of the flange seat, and the rotation axis of the circular ring body is colinear with the symmetry line of the flange seat; screws are used to connect the flanged linear bearing 5 and the bearing connecting block 6.

[0067] See also Figure 5 The bearing connection block 6 is a U-shaped structural member, a groove is provided at the upper end of the bearing connection block 6, and groove wall light through holes with colinear rotation axes are provided on the two groove walls. Two groove bottom wall light through holes with equal structures and parallel and symmetrical rotation axes are provided on the groove bottom wall of the bearing connection block 6. The diameter of the groove bottom wall light through hole is equal to the outer diameter of the annular body in the flanged linear bearing 5. Two threaded connection holes are respectively provided above and below the two groove bottom wall light through holes; the two threaded connection holes are aligned with the two light through holes on the flange seat in the flanged linear bearing 5; the No. 2 short shaft 21 is simultaneously inserted into the groove wall light through holes on the two groove walls and the 'I'-shaped light through hole on the 'I'-shaped joint 11 connected to one end of the short rod 15 in the fixed joint structure, and at the same time, one end of the 'I'-shaped joint 11 connected to one end of the short rod 15 is placed in the groove at the upper end of the bearing connection block 6.

[0068] See also Figure 8 The neck flange 8 includes a flange base and a neck. The flange base is a disc-shaped structural member. Four flange light through holes with the same structure are symmetrically arranged along the rotation axis on the flange base. The distance between the two opposite flange light through holes is equal. The four flange light through holes with the same structure on the flange base are aligned with the four leaf spring light through holes with the same structure on the leaf spring 3. A threaded through hole identical to the threaded hole in the neck is arranged at the center of the flange base; the neck is a torus, and the center hole of the neck is a threaded hole matched with the vertical shaft 23; one end of the neck is connected to the center of the flange base as a whole, and the rotation axes of the two are collinear;

[0069] See also Fig.11 The stage 7 is a rectangular plate, and 4 stage light through holes with the same structure are symmetrically arranged at the center of the longitudinal and transverse symmetric axes. The 4 stage light through holes with the same structure on the stage 7 are aligned with the 4 leaf spring light through holes with the same structure on the leaf spring 3. Bolts are inserted into the flange base of the neck flange 8, the leaf spring 3, the flange light through holes set on the stage 7, the leaf spring light holes and the stage light through holes in sequence, and then the nuts are tightened, so as to connect the neck flange 8, the leaf spring 3 and the stage 7.

[0070] 2. See Figure 1The positive stiffness mechanism includes a spring 9, a spring base No. 1 101, and a spring base No. 2 102.

[0071] The spring 9 is a cylindrical helical spring wound with spring wire. The two ends of the spring 9 are mounted on a No. 1 spring base 101 and a No. 2 spring base 102.

[0072] See also Fig. 9 , the spring base No. 1 101 comprises a bottom disc No. 1 and a hollow cylinder No. 1;

[0073] A light through hole No. 1 is provided at the center of the No. 1 bottom disc, and the diameter of the light through hole No. 1 is equal to the diameter of the vertical axis 23. The two are assembled, and the bottom surface of the No. 1 bottom disc is in contact with the bottom plane formed by four cross connectors 19 of the same structure in the middle position of two horizontal axes 24 of the same structure;

[0074] The outer diameter of the No. 1 hollow cylinder is equal to the inner diameter of the spring 9; the rotation axis of the No. 1 hollow cylinder, the No. 1 light hole and the No. 1 bottom disk in the No. 1 spring base 101 are collinear.

[0075] See also Figure 7 , the No. 2 spring base 102 comprises a No. 2 bottom disc and a No. 2 hollow cylinder;

[0076] A light through hole No. 2 is arranged at the center of the bottom disc No. 2, and the diameter of the light through hole No. 2 is equal to the diameter of the vertical axis 23. The two are matched, and the outer diameter of the bottom disc No. 2 is equal to the inner diameter of the large-diameter light hole in the two-stage stepped hole on the bottom plate 4. The bottom disc No. 2 is placed in the large-diameter light hole in the two-stage stepped hole on the bottom plate 4, and the bottom end surface of the bottom disc No. 2 contacts the annular shoulder formed in the two-stage stepped hole on the bottom plate 4 due to the diameter difference.

[0077] The outer diameter of the No. 2 hollow cylinder is equal to the inner diameter of the spring 9; the rotation axis of the No. 2 hollow cylinder, the No. 2 light hole and the No. 2 bottom disk in the No. 2 spring base 102 are collinear.

[0078] The working principle of the quasi-zero stiffness vibration isolator described in the present invention is as follows:

[0079] A quasi-zero stiffness vibration isolator uses a positive stiffness mechanism and a negative stiffness mechanism in parallel to achieve low dynamic stiffness of the overall vibration isolation system. According to the natural frequency expression of the vibration isolation system The reduced stiffness makes the vibration isolation system have a lower natural frequency; compared with the linear vibration isolation system, the quasi-zero stiffness vibration isolator has a better isolation effect on low-frequency vibrations, while maintaining a high static stiffness and being able to carry a load of a certain weight; when in use, the base plate 4 is fixed, the loading platform 7 carries heavy objects, the vibration isolator is compressed, the distance between the loading platform 7 and the base plate 4 is reduced, the bearing connection block 6 moves to both sides along the horizontal axis 24, and at the same time, the rolling bearings 17 in the fixed joint mechanisms 1 on both sides roll to both sides along the surface of the leaf spring 3, the long rod 14 rotates around the short pin 22, and the fixed angle formed by the long rod 14 and the short rod 15 is used to bend and deform the leaf spring 3, the entire negative stiffness mechanism generates negative stiffness in the vertical direction, the compression spring 9 generates positive stiffness in the vertical direction, and the negative stiffness mechanism generates negative stiffness in the vertical direction. The positive and negative stiffness cancel each other out, making the stiffness of the overall vibration isolator quasi-zero stiffness. When the loading platform 7 vibrates up and down at the equilibrium position, the dynamic stiffness of the vibration isolator is close to zero, and the natural frequency is naturally very low. Compared with the same excitation frequency, the quasi-zero stiffness isolator can produce a lower transmission rate, so that it can have a good isolation effect even for very low frequency vibrations.

Claims

1. A quasi-zero stiffness vibration isolator, characterized in that: The quasi-zero stiffness vibration isolator comprises a negative stiffness mechanism and a positive stiffness mechanism; The negative stiffness mechanism comprises two sets of fixed joint structures (1) with the same structure, a support structure (2), a leaf spring (3), a base plate (4), four linear bearings (5) with the same structure, two bearing connecting blocks (6) with the same structure, a stage (7), a flange with a neck (8), four short pins (22) with the same structure, and five short shafts No. 2 (21) with the same structure. The fixed joint structure (1) comprises three 'I'-shaped joints (11) of the same structure, three 'Y'-shaped joints (12) of the same structure, two round tube clamps (13) of the same structure, a long rod (14), a short rod (15), a first short shaft (16), two bearings (17) of the same structure and a fixed rod (18); The two ends of the long rod (14) are threadedly connected to two 'I'-shaped joints (11) of the same structure; the two ends of the short rod (15) and the 'I'-shaped joint (11) are threadedly connected to the 'Y'-shaped joint (12); the two ends of the fixed rod (18) are threadedly connected to the two 'Y'-shaped joints (12) of the same structure; one end of the long rod (14) and one end of the short rod (15) on which the 'Y'-shaped joint (12) is installed are connected by a No. 1 short shaft (16), and two bearings (17) of the same structure are sleeved on the two ends of the No. 1 short shaft (16) extending out of the 'Y'-shaped light hole on the 'Y'-shaped joint (12); the two ends of the fixed rod (18) are connected to one end of two round tube clamps (13) of the same structure sleeved on the long rod (14) and the short rod (15) through two 'Y'-shaped joints (12) of the same structure by a short pin (22); The support structure (2) further comprises four 'I'-shaped joints (11) of the same structure, nine cross connectors (19) of the same structure and two identical fixed shafts (25); Three No. 2 short shafts (21) with the same structure are respectively fixed in parallel to the left and right ends and the middle position of two identical transverse shafts (24) through two vertically arranged cross connectors (19) with the same structure; specifically: the two ends of the No. 2 short shaft (21) are respectively connected vertically to the two identical transverse shafts (24) through the cross connectors (19), wherein the No. 2 short shaft (21) fixed at the middle position of the two identical transverse shafts (24) is spatially vertically cross-connected with the vertical shaft (23) through a horizontally arranged cross connector (19), so that the two identical transverse shafts (24) are parallelly fixed to the front and rear sides of the vertical shaft (23) and spatially vertically cross-connected; the two cross connectors (19) fixed on the right side of the vertical shaft (23) at the middle position of the two identical transverse shafts (24) are used to form a bottom plane with the two cross connectors (19) fixed on the left side of the vertical shaft (23) at the middle position of the two identical transverse shafts (24), and the bottom plane is in contact with the No. 1 spring base (101); Two fixed shafts (25) with the same structure are connected to one end of the 'I'-shaped joint (11) by two short pins (22) with the same structure and the two ends of the fixed block (20); the other ends of the two fixed shafts (25) with the same structure are connected to the 'I'-shaped joint (11) by two short shafts (21) with the same structure and two symmetrical cross connectors (19) with the same structure installed at both ends of two horizontal shafts (24) with the same structure; the upper end of the vertical shaft (23) is threadedly connected to the neck flange (8); and the lower end of the vertical shaft (23) is threadedly connected to the fixed block (20); The positive stiffness mechanism comprises a spring (9), a No. 1 spring base (101) and a No. 2 spring base (102); The two sets of fixed joint structures (1) with the same structure are symmetrically installed on the left and right sides of the vertical axis (23) in the support structure (2) and are located between the two horizontal axes (24) with the same structure in the support structure (2). One end of the short rod (15) in the two sets of fixed joint structures (1) with the same structure is connected by a linear bearing (5) installed in the bearing connection block (6) and the two horizontal axes (24) with the same structure. The lower ends of the long rods (14) in the two sets of fixed joint structures (1) with the same structure and the bottom plate (4) which is sleeved on the lower end of the vertical axis (23) and located above the fixed block (20) in the support structure (2) are connected by a short pin (22); the neck flange (8) and the plate (20) are stacked from bottom to top. The spring (3) is connected to the stage (7) by bolts, the neck flange (8) is threadedly connected to the top of the vertical shaft (23), and the bottom end surface of the leaf spring (3) is in contact with and connected to four bearings (17) of the same structure in two sets of fixed joint structures (1) of the same structure; the positive stiffness mechanism is sleeved on the vertical shaft (23), the top of the positive stiffness mechanism is in contact with and connected to the bottom end surfaces of four cross connectors (19) of the same structure placed in the middle of two horizontal shafts (24) of the same structure through a No. 1 spring base (101), the bottom end of the positive stiffness mechanism is installed on the bottom plate (4) through a No. 2 spring base (102), and the spring (9) is installed between the No. 1 spring base (101) and the No. 2 spring base (102).

2. A quasi-zero stiffness vibration isolator according to claim 1, characterized in that: The cross connector (19) is a rectangular parallelepiped structural member. Both ends of the cross connector (19) are provided with optical through holes of the same structure. The rotation axes of the two optical through holes of the same structure are vertically crossed in space. The rotation axes of the two optical through holes of the same structure are equidistant from the left and right end faces. A gap of equal thickness is provided along the radial direction of the two optical through holes of the same structure and perpendicular to the left and right end faces. The gap is connected to the two optical through holes of the same structure. A threaded hole is provided on one side wall of the gap. A light hole for mounting a bolt is provided on the other side wall of the gap. The bolt is inserted into the optical through hole on one side wall and then connected to the threaded hole on the other side wall.

3. A quasi-zero stiffness vibration isolator according to claim 1, characterized in that: The fixing block (20) is a rectangular parallelepiped structural member, and U-shaped grooves of the same structure are symmetrically arranged at both ends of the fixing block (20), and light-through holes with colinear rotation axes are symmetrically arranged on the groove walls of the two U-shaped grooves of the same structure. A central threaded hole that cooperates with the threaded end of the vertical axis (23) is arranged at the center of the fixing block (20), and the rotation axis of the central threaded hole and the rotation axis of the light-through holes arranged on the groove walls of the U-shaped grooves at both ends of the fixing block (20) are spatially intersecting and perpendicular.

4. A quasi-zero stiffness vibration isolator according to claim 1, characterized in that: The bottom plate (4) comprises a base and four lugs with the same structure; The base is a rectangular plate, and a two-stage stepped through hole is arranged at the center of the base, the diameter of the small diameter section light through hole is equal to the diameter of the vertical axis (23), and the two are in sliding fit, the large diameter section light hole is equal to the outer diameter of the second spring base (102), and four light through holes are symmetrically arranged around the two-stage stepped through hole, and the center line of the four light through holes is a quadrilateral with the same symmetry axis as the base; The lug is a rectangular plate, one end of which is provided with a light through hole, the rotation axis of the light through hole is far away from the other end of the lug, i.e., the base on which it is installed, and four rectangular lugs with the same structure are vertically installed on the base, and the four rectangular lugs with the same structure are arranged parallel and symmetrically relative to the longitudinal and transverse symmetry lines of the base.

5. A quasi-zero stiffness vibration isolator according to claim 1, characterized in that: The bearing connection block (6) is a U-shaped structural member, the upper end of the bearing connection block (6) is provided with a groove, two groove walls are provided with groove wall light through holes with the rotation axis in line, the groove bottom wall of the bearing connection block (6) is provided with two groove bottom wall light through holes with the same structure and parallel and symmetrical with the rotation axis, the diameter of the groove bottom wall light through holes is equal to the outer diameter of the annular body in the flanged linear bearing (5), and threaded connection holes are respectively provided above and below the two groove bottom wall light through holes; the two threaded connection holes are aligned with the two light through holes on the flange seat in the flanged linear bearing (5).

6. A quasi-zero stiffness vibration isolator according to claim 1, characterized in that: The No. 1 spring base (101) comprises a No. 1 bottom disc and a No. 1 hollow cylinder; A light through hole No. 1 is provided at the center of the No. 1 bottom disc, and the diameter of the light through hole No. 1 is equal to the diameter of the vertical axis (23). The two are assembled, and the bottom surface of the No. 1 bottom disc is in contact with the plane formed by the bottom end surfaces of four cross connectors (19) with the same structure fixed in the middle of two horizontal axes (24) with the same structure; The outer diameter of the No. 1 hollow cylinder is equal to the inner diameter of the spring (9); one end of the No. 1 hollow cylinder is integrally connected to the upper surface of the No. 1 bottom disk; the No. 1 hollow cylinder, the No. 1 optical through hole and the No. 1 bottom disk have a colinear rotation axis.

Images