Rigidity-adjustable three-degree-of-freedom quasi-zero stiffness vibration isolator

Abstract

The rigidity-adjustable three-degree-of-freedom quasi-zero rigidity vibration isolator comprises a top plate, a first air chamber and a second air chamber, a piston is installed in the first air chamber, a supporting rod is vertically installed in the middle of the bottom of the top plate, and the bottom of the supporting rod is connected with the inner side of the bottom of the piston through a flexible spherical hinge; a negative stiffness adjusting device is installed between the outer side of the bottom of the piston and the inner side of the bottom of the first air chamber, connecting rods A are installed on the left side and the right side of the piston correspondingly, and the connecting rods A penetrate through the air holes to be connected with the ball screws through ball nuts A. A connecting rod B is installed between the two ball screws below the piston. The two ends of the connecting rod B are connected with the ball screw through ball nuts B. A metal spring A is installed between the connecting rod B and the bottom of the first air chamber, and two metal springs B are installed between the bottom of the connecting rod B and the bottom of the second air chamber in parallel. The device is large in bearing capacity and high in positioning precision, and has the capacity of adjusting the bearing capacity and rigidity.

Description

Technical Field

[0001] The invention relates to the technical field of vibration isolation devices, in particular to a three-degree-of-freedom quasi-zero-rigidity vibration isolator with adjustable stiffness. Background Art

[0002] At present, the semiconductor industry is developing rapidly. The precision requirements of semiconductor production equipment are getting higher and higher, and the equipment is becoming more and more sensitive to environmental requirements such as micro-vibration. A small amount of micro-vibration will reduce the output yield of the equipment or even make the equipment unable to work normally. Therefore, the isolation of micro-vibration is becoming more and more important.

[0003] Micro-vibration caused by external environmental vibration and internal reaction force of equipment is one of the key factors restricting the measurement accuracy of ultra-precision instruments and the manufacturing accuracy of ultra-precision processing equipment. High-performance precision micro-vibration isolation technology has become a core key technology in the fields of precision engineering and ultra-precision manufacturing. The research on this technology has important practical significance and application value. The vibration frequency of interference generated by ultra-precision measuring instruments and ultra-precision processing and manufacturing equipment is mainly low-frequency vibration within 0.8 to 100 Hz. In principle, passive vibration isolators rely on reducing their natural frequency to filter out vibrations from the outside world. The vibration isolation effect depends on the size of their natural frequency. However, the natural frequency is proportional to the arithmetic square root of the stiffness of the vibration isolator, that is, the smaller the natural frequency, the smaller the stiffness. It is difficult to break through the shackles of achieving low stiffness without affecting the load-bearing capacity.

[0004] Quasi-zero stiffness isolator is a combination isolator that connects positive and negative stiffness elastic components in parallel at a static position to achieve zero stiffness. However, most quasi-zero stiffness isolators are only designed for a single vibration isolation object. Once the isolator is manufactured, the structural parameters cannot be changed. Therefore, when the isolation mass changes, such as overload or underload, the isolator no longer has the quasi-zero stiffness characteristic. A small number of isolators can still have quasi-zero stiffness characteristics under variable loads, but the isolation mass cannot change continuously. The isolator can only maintain quasi-zero stiffness at several specific masses. The scope of application is small, and generally cannot meet the vibration isolation requirements of large loads. At the same time, there are problems such as narrow vibration isolation band and poor versatility. Summary of the invention

[0005] The purpose of the present invention is to provide a three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness to solve the problems existing in the above-mentioned background technology.

[0006] The technical solution of the present invention is implemented as follows: a three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness, comprising a top plate, a first air chamber and a second air chamber, wherein the first air chamber is located at the top of the second air chamber, the first air chamber comprises a cavity wall A, the second air chamber comprises a cavity wall B, the top of the cavity wall A is connected to the top of the cavity wall B, air holes are provided on both sides of the first air chamber, a piston is installed inside the first air chamber, the top of the piston is connected to the top of the first air chamber through an air film, a support rod is vertically installed in the middle of the bottom of the top plate, the bottom of the support rod is connected to the inner side of the bottom of the piston through a flexible ball joint, a negative stiffness adjustment device is installed between the outer side of the bottom of the piston and the inner side of the bottom of the first air chamber, the negative stiffness adjustment device comprises a permanent magnet A and an electromagnet A, the permanent magnet A is installed on the outer side of the bottom of the piston, the electromagnet A is vertically corresponding to the permanent magnet A and is installed on the inner side of the bottom of the first air chamber, a ball screw is vertically installed inside the second air chamber and on the left and right sides of the first air chamber, a connecting rod A is installed on the left and right sides of the piston, the connecting rod A passes through the air hole and is connected to the ball screw through a ball nut A A connecting rod B is installed between the two ball screws below the piston, and both ends of the connecting rod B are connected to the ball screws through ball nuts B. A metal spring A is installed between the connecting rod B and the bottom of the first air chamber, and two metal springs B are installed in parallel between the bottom of the connecting rod B and the bottom of the second air chamber. An upper support plate and a lower support plate are installed between the left and right sides of the lower part of the cavity wall A and the cavity wall B, respectively. Permanent magnets B are installed on the bottom of the upper support plate and on the left and right sides of the ball screw, and permanent magnets B are installed on the top of the lower support plate and on the left and right sides of the ball screw. An electromagnet B is separately installed, a metal conductor is installed on the ball screw and between the permanent magnet B and the electromagnet B, four metal springs C are respectively installed between the front, rear, left and right sides of the support rod and the piston, a vertical voice coil motor is installed between the left and right sides of the top of the cavity wall B and the bottom of the top plate, support plates are installed at the front, rear, left and right middle positions of the top of the cavity wall A, a horizontal voice coil motor is installed between the support plate and the support rod, an acceleration sensor and a position sensor are also installed at the bottom of the top plate, and a controller is also installed on the top of the cavity wall B.

[0007] Furthermore, the cavity wall A and cavity wall B are both made of magnetic isolation material into a rectangular structure.

[0008] Furthermore, the ball screw vertically passes through the upper support plate and the lower support plate, and a gap is left between the upper support plate and the lower support plate.

[0009] Furthermore, the top and bottom of the ball screw are vertically connected to the cavity wall B through bearings respectively.

[0010] Furthermore, a gap is left between the connecting rod A and the air hole.

[0011] Furthermore, an air inlet pipe is provided on one side of the cavity wall B, and a servo valve is installed on the air inlet pipe.

[0012] Furthermore, a limiting device is provided on the top of the support plate.

[0013] Furthermore, the controller is connected to the acceleration sensor, the position sensor, the electromagnet A, the electromagnet B, the vertical voice coil motor, and the horizontal voice coil motor through cables.

[0014] The beneficial effects of the present invention are: The present invention enlarges the volume of the air chamber and reduces the natural frequency of the system by setting two series air chambers inside and outside, which not only meets the load-bearing requirements of the carrier, but also realizes the adjustment of the positive stiffness of the system; the positive stiffness of the system is adjusted by controlling the air pressure of the first air chamber, and the negative stiffness of the system is adjusted by controlling the magnetic field strength of the negative stiffness adjustment device. The first air chamber and the negative stiffness adjustment device form a positive and negative stiffness parallel system, so that the system reaches static quasi-zero stiffness at the initial equilibrium position.

[0015] For a vertical high-frequency vibration source, the present invention realizes three-time vibration reduction of the high-frequency vibration source by driving a metal spring A, a metal spring B and an adjustable eddy current damping system in parallel with a ball screw. For a horizontal high-frequency vibration source, vibration reduction is realized by a metal spring C in parallel, so that the system can realize vibration reduction for a higher vibration frequency. For a vertical low-frequency and horizontal low-frequency vibration source, vibration reduction is realized by a voice coil motor, so that the system can realize vibration reduction for a lower vibration frequency. The system has a wide vibration isolation band and can realize vibration control of 0.1 Hz to 300 Hz.

[0016] The system of the present invention has large static rigidity and large bearing capacity, which can meet the load-bearing requirements of 7000kg precision instruments, and has high positioning accuracy and the ability to adjust the bearing capacity and rigidity. It can be adapted to precision instruments of different models, has a wide range of applications, and is highly versatile. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention.

[0018] In the figure, 1-top plate, 2-first air chamber, 201-cavity wall A, 202-air hole, 203-air film, 3-second air chamber, 301-cavity wall B, 302-intake pipe, 303-servo valve, 4-piston, 5-negative stiffness adjustment device, 501-permanent magnet A, 502-electromagnet A, 6-support rod, 7-flexible ball joint, 8-ball screw, 9-connecting rod A, 10-ball nut A, 11-connecting rod B , 12-ball nut B, 13-metal spring A, 14-metal spring B, 15-upper support plate, 16-lower support plate, 17-permanent magnet B, 18-electromagnet B, 19-metal conductor, 20-metal spring C, 21-vertical voice coil motor, 22-support plate, 23-lateral voice coil motor, 24-acceleration sensor, 25-position sensor, 26-controller, 27-bearing, 28-limit device. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be described clearly and completely in conjunction with the embodiments below. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] like Figure 1As shown, a three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness includes a top plate 1, a first air chamber 2 and a second air chamber 3, wherein the first air chamber 2 is located at the top of the second air chamber 3, the first air chamber 2 includes a cavity wall A201, the second air chamber 3 includes a cavity wall B301, the top of the cavity wall A201 is connected to the top of the cavity wall B301, air holes 202 are opened on both sides of the first air chamber 2, a piston 4 is installed inside the first air chamber 2, the top of the piston 4 is connected to the top of the first air chamber 2 through an air film 203, a support rod 6 is vertically installed in the middle of the bottom of the top plate 1, and the bottom of the support rod 6 is connected to the inner side of the bottom of the piston 4 through a flexible ball The piston 4 is connected with a hinge 7, and a negative stiffness adjustment device 5 is installed between the outer side of the bottom of the piston 4 and the inner side of the bottom of the first air chamber 2. The negative stiffness adjustment device 5 includes a permanent magnet A501 and an electromagnet A502. The permanent magnet A501 is installed on the outer side of the bottom of the piston 4, and the electromagnet A502 is installed vertically corresponding to the permanent magnet A501 on the inner side of the bottom of the first air chamber 2. Ball screws 8 are vertically installed inside the second air chamber 3 and on the left and right sides of the first air chamber, respectively. Connecting rods A9 are installed on the left and right sides of the piston 4, respectively. The connecting rods A9 pass through the air holes 202 and are connected to the ball screws 8 through ball nuts A10. The bottom of the piston 4 A connecting rod B11 is installed between the two ball screws 8, and both ends of the connecting rod B11 are connected to the ball screws 8 through ball nuts B12. A metal spring A13 is installed between the connecting rod B11 and the bottom of the first air chamber 2. Two metal springs B14 are installed in parallel between the bottom of the connecting rod B11 and the bottom of the second air chamber 3. An upper support plate 15 and a lower support plate 16 are installed between the left and right sides of the lower part of the cavity wall A201 and the cavity wall B301, respectively. Permanent magnets B17 are installed on the bottom of the upper support plate 15 and on the left and right sides of the ball screw 8, respectively. Electromagnets are installed on the top of the lower support plate 16 and on the left and right sides of the ball screw 8, respectively. Iron B18, a metal conductor 19 is installed on the ball screw 8 and between the permanent magnet B17 and the electromagnet B18, four metal springs C20 are respectively installed between the front, rear, left and right sides of the support rod 6 and the piston 4, a vertical voice coil motor 21 is installed between the left and right sides of the top of the cavity wall B301 and the bottom of the top plate 1, support plates 22 are installed at the front, rear, left and right middle positions of the top of the cavity wall A201, a horizontal voice coil motor 23 is installed between the support plate 22 and the support rod 6, an acceleration sensor 24 and a position sensor 25 are also installed at the bottom of the top plate 1, and a controller 26 is also installed on the top of the cavity wall B301.

[0021] The cavity wall A201 and the cavity wall B301 are both made of magnetic isolation material and have a rectangular structure.

[0022] The ball screw 8 vertically passes through the upper support plate 15 and the lower support plate 16 , and a gap is left between the upper support plate 15 and the lower support plate 16 .

[0023] The top and bottom of the ball screw 8 are vertically connected to the cavity wall B301 through bearings 27 respectively.

[0024] A gap is left between the connecting rod A9 and the air hole 202 .

[0025] An air inlet pipe 302 is provided on one side of the cavity wall B301 , and a servo valve 303 is installed on the air inlet pipe 302 .

[0026] The top of the support plate 22 is provided with a limiting device 28 , which is a rubber block. The limiting device 28 is mainly used to prevent the equipment from being damaged when the system air pressure is too low.

[0027] The controller 26 is connected to the acceleration sensor 24 , the position sensor 25 , the electromagnet A502 , the electromagnet B18 , the vertical voice coil motor 21 , and the horizontal voice coil motor 23 through cables.

[0028] During installation, the precision instrument is placed on the top plate 1, and then the air pressure of the first air chamber 2 is controlled by adjusting the servo valve 303 according to the weight of the precision instrument to meet the load-bearing requirements. At the same time, the air pressure of the first air chamber 2 can be adjusted by the servo valve 303 to adjust the positive stiffness of the system; the current of the electromagnet A of the negative stiffness adjustment device 5 is controlled by the controller 26, so as to control the strength of the electromagnetic field generated by it, and then control the negative stiffness, forming a positive and negative stiffness parallel system with the first air chamber 2, adjusting the vertical positive and negative stiffness of the system, so that the system reaches a static quasi-zero stiffness at the initial equilibrium position, at which time the metal spring A13, metal spring B14 and metal spring C20 are all in a natural expansion and contraction state.

[0029] During operation, vibration signals are collected by the acceleration sensor 24 and the position sensor 25 , and then the signals are transmitted to the controller 26 . When the high-frequency vibration source is vertical, the piston 4 will move up and down, which will drive the ball screw 8 to rotate, and then drive the connecting rod B to move up and down. At this time, the parallel metal spring A and metal spring B will achieve two high-frequency vibration reductions. At the same time, the rotation of the ball screw 8 will drive the metal conductor 19 to rotate. Since there is a vertical magnetic field between the permanent magnet B17 and the electromagnet B18, when the metal conductor 19 rotates in the vertical magnetic field, eddy currents will be generated. The magnetic field excited by the eddy currents is opposite to the vertical magnetic field, thereby generating a damping effect and achieving the third high-frequency vibration reduction. The current of the electromagnet B18 can be controlled by the controller 26 to control the strength of the vertical magnetic field and then adjust the damping size of the eddy currents to adjust its vibration reduction performance; when the low-frequency vibration source is vertical, the vertical voice coil motor 21 is controlled by the controller 26 to achieve low-frequency vibration reduction; when the high-frequency vibration source is horizontal, the high-frequency vibration reduction is achieved by the parallel metal spring C20; when the low-frequency vibration source is horizontal, the horizontal voice coil motor 23 is controlled by the controller 26 to achieve low-frequency vibration reduction.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness, comprising a top plate, a first air chamber and a second air chamber, characterized in that: The first air chamber is located at the top of the second air chamber, the first air chamber includes a cavity wall A, the second air chamber includes a cavity wall B, the top of the cavity wall A is connected to the top of the cavity wall B, air holes are opened on both sides of the first air chamber, a piston is installed inside the first air chamber, the top of the piston is connected to the top of the first air chamber through an air film, a support rod is vertically installed in the middle of the bottom of the top plate, the bottom of the support rod is connected to the inner side of the bottom of the piston through a flexible ball joint, a negative stiffness adjustment device is installed between the outer side of the bottom of the piston and the inner side of the bottom of the first air chamber, the negative stiffness adjustment device includes a permanent magnet A and an electromagnet A, the permanent magnet A is installed on the outer side of the bottom of the piston, the electromagnet A is vertically corresponding to the permanent magnet A and is installed on the inner side of the bottom of the first air chamber, ball screws are vertically installed inside the second air chamber and on the left and right sides of the first air chamber, connecting rods A are installed on the left and right sides of the piston, the connecting rod A passes through the air hole and is connected to the ball screw through a ball nut A, and a connecting rod B is installed between the two ball screws below the piston , the two ends of the connecting rod B are connected to the ball screw through a ball nut B, a metal spring A is installed between the connecting rod B and the bottom of the first air chamber, two metal springs B are installed in parallel between the bottom of the connecting rod B and the bottom of the second air chamber, an upper support plate and a lower support plate are installed between the left and right sides of the lower part of the cavity wall A and the cavity wall B, respectively, a permanent magnet B is installed at the bottom of the upper support plate and the left and right sides of the ball screw, an electromagnet B is installed at the top of the lower support plate and the left and right sides of the ball screw, a metal conductor is installed on the ball screw and between the permanent magnet B and the electromagnet B, four metal springs C are installed between the front, rear, left and right of the support rod and the piston, a vertical voice coil motor is installed between the left and right sides of the top of the cavity wall B and the bottom of the top plate, support plates are installed at the front, rear, left and right middle positions of the top of the cavity wall A, a horizontal voice coil motor is installed between the support plate and the support rod, an acceleration sensor and a position sensor are also installed at the bottom of the top plate, and a controller is also installed at the top of the cavity wall B.

2. The three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness according to claim 1, characterized in that: The cavity wall A and cavity wall B are both made of magnetic isolation material and have a rectangular structure.

3. The three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness according to claim 1, characterized in that: The ball screw vertically passes through the upper support plate and the lower support plate, and a gap is left between the ball screw and the upper support plate and the lower support plate.

4. The three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness according to claim 1, characterized in that: The top and bottom of the ball screw are vertically connected to the cavity wall B through bearings respectively.

5. The three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness according to claim 1, characterized in that: A gap is left between the connecting rod A and the air hole.

6. The three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness according to claim 1, characterized in that: An air inlet pipe is provided on one side of the cavity wall B, and a servo valve is installed on the air inlet pipe.

7. The three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness according to claim 1, characterized in that: The top of the support plate is provided with a limiting device.

8. The three-degree-of-freedom quasi-zero stiffness vibration isolator with adjustable stiffness according to claim 1, characterized in that: The controller is connected with the acceleration sensor, the position sensor, the electromagnet A, the electromagnet B, the vertical voice coil motor, and the horizontal voice coil motor through cables.

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