Non-circular gear-magnetic negative stiffness coupled quasi-zero stiffness vibration isolation device

Abstract

The invention belongs to the technical field of mechanical vibration isolation, and particularly relates to a non-circular gear-magnetic negative stiffness coupled quasi-zero stiffness vibration isolation device. According to the non-circular gear-magnetic negative stiffness coupled quasi-zero stiffness vibration isolation device, the non-linear motion characteristic of a non-circular gear transmission mechanism and the adjustable non-contact force of a magnetic negative stiffness mechanism can be combined through a vibration isolator, and the adjustable quasi-zero stiffness characteristic within the wide displacement range is formed near the balance position. Therefore, the low-frequency vibration isolation performance is effectively improved. According to the technical scheme, the non-circular gear-magnetic negative stiffness coupled quasi-zero stiffness vibration isolation device comprises an upper bottom plate and a lower bottom plate which are horizontally arranged and vertically and correspondingly arranged, and vertical guide structures which are connected between the upper bottom plate and the lower bottom plate and symmetrically arranged in the left-right direction; the device is characterized by further comprising a gear rack mechanism and a non-circular gear transmission mechanism which are arranged between the upper bottom plate and the lower bottom plate.

Description

Technical Field

[0001] This invention belongs to the field of mechanical vibration isolation technology, specifically relating to a quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling. Background Technology

[0002] With the rapid development of high-end technology fields such as precision machining, aerospace, and precision measurement, vibration control technology is facing increasingly stringent performance requirements. Especially in typical application scenarios such as ultra-precision machining equipment, optical inspection instruments, and spacecraft payloads, there is often a need for effective isolation and suppression of low-frequency or even ultra-low-frequency vibrations. Traditional linear vibration isolators, constrained by their own linear stiffness, have an inherent design contradiction between their natural frequency and load-bearing capacity, making it difficult to achieve good low-frequency vibration isolation while maintaining sufficient load-bearing performance.

[0003] Quasi-zero stiffness isolators are based on the principle of parallel positive and negative stiffness mechanisms. They can achieve extremely low dynamic stiffness near the equilibrium position, thereby significantly reducing the system's natural frequency and expanding the isolation frequency band. Currently, existing quasi-zero stiffness isolators mainly use mechanical springs, magnetic springs, or air springs to generate negative stiffness, but these still generally suffer from problems such as difficulty in adjustment, limited nonlinear characteristics, and difficulty in maintaining quasi-zero stiffness characteristics over a wide displacement range.

[0004] Non-circular gears, as a special transmission mechanism capable of achieving specific nonlinear transmission ratios, are not yet widely used in vibration isolation. While magnetic stiffness mechanisms offer advantages such as non-contact, frictionless operation, and ease of adjustment, they often struggle to achieve quasi-zero stiffness characteristics over a wide frequency range when used alone. Therefore, there is an urgent need to develop a novel quasi-zero stiffness vibration isolator that combines the nonlinear transmission characteristics of non-circular gears with the advantages of magnetic negative stiffness mechanisms to overcome the limitations of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling. This vibration isolator can combine the nonlinear motion characteristics of the non-circular gear transmission mechanism with the adjustable non-contact force of the magnetic negative stiffness mechanism to form quasi-zero stiffness characteristics within an adjustable wide displacement range near the equilibrium position, thereby effectively improving low-frequency vibration isolation performance.

[0006] The technical solution provided by this invention is: A quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling includes an upper base plate and a lower base plate arranged horizontally and correspondingly arranged vertically, and a vertical guide structure connected between the upper base plate and the lower base plate and symmetrically arranged in the left and right directions. The device is characterized in that it further includes a gear rack mechanism and a non-circular gear transmission mechanism arranged between the upper base plate and the lower base plate. The gear and rack mechanism includes a circular gear that can rotate along a horizontal axis and a rack that is vertically fixed to the upper base plate and meshes with the circular gear. The non-circular gear transmission mechanism includes a first non-circular gear coaxially connected to the circular gear, a second non-circular gear rotatable along a horizontal axis and meshing with the first non-circular gear, and an array of permanent magnets mounted on the second non-circular gear.

[0007] The circular gear and the first non-circular gear are coaxially fixed to a horizontally arranged first connecting shaft, and the second non-circular gear is fixed to a horizontally arranged second connecting shaft; the two ends of the first connecting shaft are rotatably positioned on the lower base plate by two support seats, and the second connecting shaft is arranged parallel to the first connecting shaft and its two ends are fixed to the lower base plate by two support seats.

[0008] The first non-circular gear and the second non-circular gear have the same number of teeth and the same tip circle outer contour.

[0009] The permanent magnet array includes a plurality of first permanent magnets mounted on the end face of the second non-circular gear and a plurality of second permanent magnets mounted on the second connecting shaft; the plurality of first permanent magnets and the plurality of second permanent magnets are coaxially arranged with the second non-circular gear and arranged in two annular rings of different diameters.

[0010] The second non-circular gear has a large shaft hole and is coaxially provided with several first positioning grooves that pass through both ends of the non-circular gear and are arranged in a ring; several first permanent magnets are inserted into the several first positioning grooves and are sealed by two baffles; so as to realize the installation of the first permanent magnets.

[0011] A cylindrical protrusion, which is compatible with the shaft hole of the second non-circular gear, is coaxially fixed on the second connecting shaft. A plurality of second positioning grooves, which pass through both end faces and are arranged in a ring, are coaxially provided on the protrusion. The plurality of second permanent magnets are inserted into the plurality of second positioning grooves one by one, and are simultaneously sealed by the two baffles to realize the installation of the second permanent magnets.

[0012] The axial thickness of the protrusion is the same as the length of the shaft hole of the second non-circular gear, and the outer diameter is suitable for the shaft hole of the second non-circular gear, so that a relative sliding fit can be performed in the shaft hole.

[0013] The rack is vertically fixed to the bottom of the upper base plate via a rack seat, thus becoming an integral part of the upper base plate.

[0014] The vertical guide structure includes a first guide rod and a second guide rod that are vertically and symmetrically arranged on the left and right sides of the device; the bottom ends of the two guide rods are fixed to the bottom plate, and the upper ends of the two guide rods are slidably engaged with the slide cylinder connected to the bottom plate.

[0015] Springs are fitted onto the two guide rods, with the two ends of the springs abutting against the lower base plate and the slide cylinder, respectively, thus providing positive stiffness to the upper base plate.

[0016] The beneficial effects of this invention are: 1) Excellent low-frequency vibration isolation performance: By combining the nonlinear negative stiffness precisely generated by the non-circular gear transmission mechanism with the negative stiffness generated by the magnetic negative stiffness mechanism, and connecting it in parallel with the linear positive stiffness spring, a "quasi-zero stiffness" state can be achieved within a wide displacement range near the system's equilibrium position. This greatly reduces the system's natural frequency, thereby effectively isolating low-frequency and even ultra-low-frequency vibrations and expanding the vibration isolation frequency band.

[0017] 2) Adjustability and Adaptability: This invention features unique adjustability. By adjusting the gap between the magnets, the magnitude of the magnetic negative stiffness can be changed; by adjusting the initial meshing phase of the non-circular gears, the output characteristics of the nonlinear stiffness can be optimized. This design allows the vibration isolator to adapt to different load conditions and operating requirements, achieving optimized performance matching and making its application more flexible.

[0018] 3) Compact structure and easy integration: The entire device integrates gear transmission, magnetic mechanism, guide mechanism and other components into a support frame. The structure is compact and reasonable, with high space utilization, making it easy to install and use in space-constrained precision equipment.

[0019] 4) Controllable and superior nonlinear characteristics: Non-circular gears can generate specific and complex nonlinear stiffness characteristics according to a preset transmission ratio curve. This actively designed nonlinear characteristic is more accurate and controllable than many passively generated nonlinear characteristics, which helps to maintain an ideal near-zero stiffness effect over a wider displacement range and improve vibration isolation performance. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the main structure of an embodiment of the present invention.

[0021] Figure 2 This is an isometric view of an embodiment of the present invention.

[0022] Figure 3 yes Figure 1 Diagram showing the connection relationships between the upper and lower base plates, support base, guide rod, and springs.

[0023] Figure 4 yes Figure 1 Schematic diagram of the connection structure between the medium circular gear and the first non-circular gear (exploded state).

[0024] Figure 5 yes Figure 1 A schematic diagram of the arrangement of permanent magnets in the second non-circular gear (the arrows in the diagram indicate the direction of the magnetic field lines of each magnet).

[0025] Figure 6 yes Figure 1 Exploded view of the second non-circular gear.

[0026] Icon labels: 1-1, First guide rod; 1-2, First spring; 1-3, Lower base plate; 1-4, First support seat; 1-5, Second support seat; 1-6, Third support seat; 1-7, Fourth support seat; 1-8, Second guide rod; 1-9, Second spring; 2-1, First bushing; 2-2, Circular gear; 2-3, First connecting shaft; 2-4, First non-circular gear; 2-5, Second bushing; 3, Second non-circular gear; 3-1, Third bushing; 3-2, First baffle; 3-3, Second non-circular gear; 3-31, First positioning groove; 3-4, Second connecting shaft; 3-41, Protrusion; 3-411, Second positioning groove; 3-5, Second baffle; 3-6, Fourth bushing; 4-1, Upper base plate; 4-2, Rack; 4-3, Rack seat; 5, First permanent magnet; 6, Second permanent magnet. Detailed Implementation

[0027] The following description, in conjunction with the embodiments shown in the accompanying drawings, provides further details.

[0028] Figure 1 The non-circular gear-magnetic negative stiffness coupled quasi-zero stiffness vibration isolation device shown includes a lower base plate, an upper base plate, a vertical guide structure, a gear and rack mechanism, and a non-circular gear mechanism.

[0029] like Figure 3 As shown, the lower base plate 1-3 is horizontally arranged, and the upper base plate 4-1 is located above the lower base plate 1-3 and is horizontally arranged. The two base plates are connected by a vertically arranged and parallel first guide rod 1-1 and a second guide rod 1-8. The first guide rod 1-1 and the second guide rod 1-8 are symmetrically arranged on the left and right sides of the two base plates, respectively. The first support seat 1-4 and the second support seat 1-5 are fixedly installed on the front and rear directions of the upper surface of the lower base plate 1-3, and the top of each has a shaft hole. The first connecting shaft 2-3 is horizontally arranged, and its two ends are rotatably inserted and positioned in the shaft holes of the first support seat 1-4 and the second support seat 1-5 through bearings. The third support 1-6 and the fourth support 1-7, which have the same structure as the first support, are also fixedly installed on the upper surface of the lower base plate 1-3 in the front-rear direction, and are symmetrically arranged with the first support 1-4 and the second support 1-5 in the left-right direction; the second connecting shaft 3-4 is arranged parallel to the first connecting shaft, and its two ends are respectively inserted and fixed in the shaft holes of the third support 1-6 and the fourth support 1-7. As shown in the figure, the first connecting shaft and the second connecting shaft are supported by the support and are symmetrically arranged on the lower base plate.

[0030] A sliding cylinder is vertically fixed on each of the left and right sides of the lower surface of the upper base plate 4-1, and the inner diameter of the sliding cylinder is compatible with the guide rod. The first guide rod 1-1 and the second guide rod 1-8 are symmetrically arranged on the left and right sides of the upper base plate 4-1 and the lower base plate 1-3. The bottom ends of the two guide rods are fixed to the lower base plate, and the upper ends of the two guide rods are slidably inserted into the sliding cylinder, thus forming a vertical guide structure. The first spring 1-2 and the second spring 1-9 are respectively sleeved on the first guide rod 1-1 and the second guide rod 1-8, and the two ends of the springs abut against the lower base plate and the sliding cylinder, respectively, thereby providing positive stiffness to the upper base plate 4-1.

[0031] The gear and rack mechanism includes a circular gear 2-2 and a rack 4-2 meshing with it. The rack 4-2 is vertically fixed below the upper base plate 4-2 by a rack seat 4-3, thus becoming an integral part of the upper base plate. The circular gear 2-2 is fitted onto the first connecting shaft and is keyed to the first connecting shaft. One end face of the circular gear is limited by the step of the first connecting shaft, and the other end face is limited by the first bushing 2-1 (limiting the distance between it and the first support seat 1-4), thus meshing with the rack.

[0032] The non-circular gear transmission mechanism includes a first non-circular gear 2-4 and a second non-circular gear 3-3 meshing with the first non-circular gear 2-4; the first non-circular gear 2-4 is also coaxially mounted on the first connecting shaft 2-3 together with the circular gear, and the mounting method is the same as that of the circular gear; one end face of the first non-circular gear 2-4 is limited by the step of the first connecting shaft, and the other end face is limited by the second bushing 2-5 (limiting the distance between it and the second support seat 1-5).

[0033] Depend on Figure 6It can be seen that the second non-circular gear 3-3 is mounted on the second connecting shaft 3-4. The second non-circular gear 3-3 has a large shaft hole, and its end face is provided with a number of first positioning grooves 3-31 (6 in this embodiment) for mounting the first permanent magnet. These first positioning grooves are arranged in a ring that is coaxial with the second non-circular gear and has a distance between them. Each first positioning groove passes through both end faces of the non-circular gear and is fitted with a first permanent magnet 5 (6 in this embodiment) with a suitable shape profile. A cylindrical protrusion 3-41 is coaxially fixed on the second connecting shaft 3-4. The axial thickness of the protrusion is the same as the length of the shaft hole of the second non-circular gear, and the outer diameter is suitable for the shaft hole of the second non-circular gear, so that relative sliding fit can be performed in the shaft hole. A plurality of second positioning grooves 3-41 are provided on the protrusion (6 in this embodiment). These second positioning grooves are arranged in a ring coaxial with the second connecting shaft and spaced apart from each other. Each second positioning groove passes through both end faces of the protrusion and is fitted with a second permanent magnet 6 (6 in this embodiment) with a suitable outer contour. All the first permanent magnets 5 and all the second permanent magnets 6 together form a permanent magnet array. The first baffle 3-2 and the second baffle 3-5 are sleeved on the second connecting shaft 3-4 and fixed to the two end faces of the second non-circular gear 3-3 by bolts, respectively, for fixing and limiting the first permanent magnet and the second permanent magnet; and the two ends of the second connecting shaft are respectively sleeved with the third bushing 3-1 and the fourth bushing 3-6, for limiting the distance between the first baffle and the third support seat and the distance between the second baffle and the fourth support seat, respectively.

[0034] Furthermore, such as Figure 5 As shown: among the plurality of first permanent magnets, the magnetic field lines of two adjacent first permanent magnets are in opposite directions, namely radially inward and radially outward, respectively; among the plurality of second permanent magnets, the magnetic field lines of two adjacent second permanent magnets are in opposite directions, namely radially inward and radially outward, respectively. In the balanced state of this device, the magnetic field lines of the first and second permanent magnets in the same radial direction are in the same direction.

[0035] Working principle: When the upper base plate 4-1 is subjected to external vibration and undergoes vertical displacement, it drives the rack 4-2 to move as well. The rack 4-2 drives the circular gear 2-2 and its coaxial first non-circular gear 2-4 to rotate. The first non-circular gear 2-4, through meshing transmission, drives the second non-circular gear 3-3 to generate a specific non-linear rotational motion around the protrusion of the second connecting shaft (while the second connecting shaft remains stationary). The first permanent magnet fixed on the second non-circular gear 3-3 moves accordingly, causing a change in its relative position with the second permanent magnet fixed on the second connecting shaft 3-4, thereby generating a non-linearly changing magnetic force. This magnetic force provides negative stiffness near the system's equilibrium position. This negative stiffness, in parallel with the positive stiffness provided by the first spring 1-2 and the second spring 1-9, cancels each other out near the equilibrium position, making the system's combined stiffness close to zero, forming a quasi-zero stiffness region, thus achieving a low-frequency vibration isolation effect.

Claims

1. A quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling, comprising an upper base plate (4-1) and a lower base plate (1-3) arranged horizontally and correspondingly positioned vertically, and a vertical guide structure connected between the upper base plate and the lower base plate and symmetrically arranged in the left-right direction, characterized in that: The device also includes a gear and rack mechanism and a non-circular gear transmission mechanism disposed between the upper base plate and the lower base plate; The gear and rack mechanism includes a circular gear (2-2) that can rotate along a horizontal axis and a rack (4-2) that is vertically fixed to the upper base plate and meshes with the circular gear. The non-circular gear transmission mechanism includes a first non-circular gear (2-4) coaxially connected to the circular gear, a second non-circular gear (3-3) rotatable along a horizontal axis and meshing with the first non-circular gear, and an array of permanent magnets mounted on the second non-circular gear.

2. The quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling according to claim 1, characterized in that: the circular gear and the first non-circular gear are coaxially fixed on a horizontally arranged first connecting shaft (2-3), and the second non-circular gear is fixed on a horizontally arranged second connecting shaft (3-4); the two ends of the first connecting shaft are rotatably positioned on the lower base plate by two support seats, and the second connecting shaft is arranged parallel to the first connecting shaft and its two ends are fixed on the lower base plate by two support seats.

3. The quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling according to claim 2, characterized in that: the first non-circular gear and the second non-circular gear have the same number of teeth and the same tooth tip circle outer contour.

4. The quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling according to claim 3, characterized in that: the permanent magnet array includes a plurality of first permanent magnets (5) installed on the end face of the second non-circular gear and a plurality of second permanent magnets (6) installed on the second connecting shaft; the plurality of first permanent magnets and the plurality of second permanent magnets are coaxially arranged with the second non-circular gear and arranged in two annular rings with different diameters.

5. The quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling according to claim 4, characterized in that: the second non-circular gear (3-3) has a large shaft hole and is coaxially provided with a plurality of first positioning grooves (3-31) that pass through both ends of the second non-circular gear and are arranged in a ring; a plurality of first permanent magnets (5) are inserted one by one into the plurality of first positioning grooves and are sealed by two baffles; so as to realize the installation of the first permanent magnets.

6. The quasi-zero stiffness vibration isolation device of non-circular gear-magnetic negative stiffness coupling according to claim 7, characterized in that: a cylindrical protrusion (3-41) that is compatible with the shaft hole of the second non-circular gear is coaxially fixed on the second connecting shaft (3-4), and a plurality of second positioning grooves (3-411) that pass through both end faces and are arranged in a ring are coaxially provided on the protrusion; the plurality of second permanent magnets (6) are inserted into the plurality of second positioning grooves one by one, and are simultaneously blocked by the two baffles to realize the installation of the second permanent magnets.

7. The quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling according to claim 6, characterized in that: the axial thickness of the protrusion is the same as the length of the shaft hole of the second non-circular gear, and the outer diameter is suitable for the shaft hole of the second non-circular gear, so that it can be relatively slidingly fitted with the shaft hole.

8. The quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling according to claim 7, characterized in that: the rack is vertically fixed below the upper base plate by the rack seat (4-3), thereby being integrated with the upper base plate.

9. The quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling according to claim 8, characterized in that: the vertical guide structure includes a first guide rod (1-1) and a second guide rod (1-8) vertically and symmetrically arranged on the left and right sides of the device; the bottom ends of the two guide rods are fixed to the lower base plate, and the upper ends of the two guide rods are slidably engaged with the slide cylinder connected to the lower base plate.

10. The quasi-zero stiffness vibration isolation device with non-circular gear-magnetic negative stiffness coupling according to claim 9, characterized in that: springs are respectively sleeved on the two guide rods, and the two ends of the springs abut against the lower base plate and the slide cylinder respectively, thereby providing positive stiffness for the upper base plate (4-1).

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