CN116989096A - Longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity - Google Patents
Longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
- F16F15/10—Suppression of vibrations in rotating systems by making use of members moving with the system
- F16F15/18—Suppression of vibrations in rotating systems by making use of members moving with the system using electric, magnetic or electromagnetic means
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Abstract
The invention discloses a longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity, which is characterized in that a magnetic spring and a spiral arm torsion spring are connected in parallel on a central shaft; the magnetic spring is a negative stiffness spring with longitudinal negative stiffness and torsional negative stiffness, and the negative stiffness spring is composed of an outer magnetic ring and an inner magnetic ring which are coaxially arranged on a central shaft and can rotate relatively; the inner magnetic ring is fixedly connected with the central shaft, and the outer magnetic ring is positioned at the periphery of the inner magnetic ring; the spiral arm torsion spring is a positive stiffness spring with longitudinal positive stiffness and torsional positive stiffness, and the positive stiffness spring is composed of a first spiral arm torsion spring and a second spiral arm torsion spring which are arranged at two ends of a central shaft; the first spiral arm torsion spring and the second spiral arm torsion spring are fixedly sleeved on the central shaft through central holes and fixedly connected with the outer magnetic ring through peripheral through holes. The invention enables the vibration isolator to obtain high static rigidity and low dynamic rigidity characteristics in the longitudinal and torsion directions, effectively reduces the longitudinal rigidity and the torsion rigidity of the static balance position, and realizes the longitudinal and torsion coupling low-frequency vibration isolation.
Description
Technical Field
The invention relates to a vibration isolator, in particular to a vibration isolator for inhibiting low-frequency torsional vibration, low-frequency longitudinal vibration and coupled vibration response of a shafting.
Background
Mechanical vibration is commonly used in production activities, although vibration screening, vibration conveying and vibration pile sinking are often performed by utilizing vibration phenomena in industry, so that a plurality of convenience is provided for actual production activities; however, under most working conditions, vibration can damage mechanical systems, affect production practices, and even endanger life safety of workers. Shafting is commonly used in the fields of automobiles, ships, aerospace and the like, the shafting has the problems of longitudinal vibration and torsional vibration in the process of transmitting force and moment, the longitudinal vibration and the torsional vibration are often coupled, and the effect of independently inhibiting the longitudinal vibration or the torsional vibration is not ideal; in shafting of various precision equipment, low-frequency vibration responses lower than 10Hz are often existed, and if the low-frequency vibration responses cannot be effectively restrained, the damage such as mechanical fracture, fatigue damage, processing precision reduction, overlarge working noise and the like can be brought to precision devices, so that the vibration responses need to be effectively controlled.
In actual engineering, the vibration response source of the shafting is very complex, the vibration response source is difficult to inhibit from the source, and the vibration isolation technology is the preferred control method; in recent years, related researches show that compared with the traditional vibration isolation device, the nonlinear vibration isolation device can solve the problem of low-frequency and even ultra-low-frequency vibration control, and common shafting nonlinear vibration isolation devices comprise: torsion spring vibration isolator, high internal pressure air bag vibration isolator, inclined ring spring vibration isolator, but these shafting nonlinear vibration isolators have limited bearing capacity and unstable performance. Therefore, the passive quasi-zero stiffness vibration isolator designed by parallel connection of the negative stiffness structure and the positive stiffness element is widely focused, the vibration isolator has high static stiffness, can reduce static displacement, can provide smaller dynamic stiffness near a vibration balance position, reduces the resonance frequency of a system, and further improves the vibration isolation performance of the system; the passive quasi-zero stiffness vibration isolator has a good isolation effect on small-displacement vibration response, but cannot effectively isolate low-frequency large-displacement vibration response due to strong nonlinearity of the stiffness of the magnetic spring.
"a semi-active control vibration isolation system for longitudinal vibration of a propulsion shafting" is disclosed in patent document with publication number CN212220526U, "an inertial-to-capacity metamaterial vibration isolator for torsional vibration suppression of a rotor system" is disclosed in patent document with publication number CN114877019a, "a high-temperature superconductive magnetic levitation flywheel radial vibration isolation device" is disclosed in patent document with publication number CN114412963a, which are vibration isolators for suppressing longitudinal vibration response, torsional vibration response and radial vibration response of a shafting or rotor system, but these vibration isolators can only suppress vibration response of a single degree of freedom, and no effective vibration isolation device is yet available for coping with low-frequency vibration response of longitudinal and torsional coupling.
Disclosure of Invention
The invention aims to avoid the problems in the prior art and provides a longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity, so as to effectively isolate low-frequency longitudinal vibration, low-frequency torsional vibration and coupled vibration response of a shafting along the longitudinal and torsional directions.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention relates to a longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity, which is characterized in that:
the vibration isolator is used for power transmission between the outer end cover and the central shaft and isolating interference torque and interference longitudinal force; a magnetic spring and a spiral arm torsion spring are arranged on the central shaft in parallel;
the magnetic spring is a negative stiffness spring which is formed by an outer magnetic ring and an inner magnetic ring which are coaxially arranged on a central shaft and can rotate relatively and has longitudinal negative stiffness and torsional negative stiffness; the inner magnetic ring is fixedly connected with the central shaft, and the outer magnetic ring is positioned at the periphery of the inner magnetic ring;
the spiral arm torsion spring is a positive stiffness spring with longitudinal positive stiffness and torsional positive stiffness, and the positive stiffness spring is composed of a first spiral arm torsion spring and a second spiral arm torsion spring which are arranged at two ends of a central shaft; the first spiral arm torsion spring and the second spiral arm torsion spring are fixedly sleeved on the central shaft through central holes and fixedly connected with the outer magnetic ring through peripheral through holes;
the negative stiffness spring and the positive stiffness spring which are arranged in parallel are utilized to enable the vibration isolator to obtain high static stiffness and low dynamic stiffness characteristics in the longitudinal direction and the torsion direction, so that the longitudinal stiffness and the torsion stiffness of a static balance position are reduced, and the longitudinal and torsion coupling low-frequency vibration isolation is realized.
The longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity is also characterized in that:
the outer magnetic ring in the magnetic spring is formed by arranging a plurality of rubidium-iron-boron outer ring magnetic shoes which are magnetized in a circumferential direction, each outer ring magnetic shoe is clamped and fixed with the outer magnetic ring clamping teeth on the inner wall of the outer magnetic ring clamping groove, and two ends of the outer magnetic ring are respectively fastened by the left end cover and the right end cover of the outer magnetic ring;
the inner magnetic ring in the magnetic spring is formed by arranging a plurality of rubidium-iron-boron inner ring magnetic shoes which are magnetized in a circumferential direction, each inner ring magnetic shoe is clamped and fixed with inner magnetic ring clamping teeth on the inner wall of the inner magnetic ring clamping groove, and two ends of the inner magnetic ring are respectively fastened by an inner magnetic ring left baffle plate and an inner magnetic ring right baffle plate;
the outer ring magnetic shoes and the inner ring magnetic shoes are equal in number, and in the magnetic springs at the balance positions, the outer ring magnetic shoes and the inner ring magnetic shoes at the corresponding radial positions are magnetized in the same direction, and the sector angles are centered with the longitudinal heights.
The longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity is also characterized in that:
setting the magnetizing directions of adjacent outer ring magnetic shoes to be the same;
or the magnetizing directions of the adjacent outer ring magnetic shoes are set to be opposite, the number of the outer ring magnetic shoes is 2N, and N is an integer;
the longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity is also characterized in that:
the first spiral arm torsion spring is sleeved at the left end of the central shaft through a first central hole of the first spiral arm torsion spring, and is fixed on a first shaft shoulder of the central shaft through a first nut by utilizing a first thread section on the central shaft;
the second spiral arm torsion spring is sleeved at the right end of the central shaft through a second central hole of the second spiral arm torsion spring, and is fixed on a second shoulder of the central shaft through a third threaded section of the central shaft through a second nut;
the outer magnetic ring clamping groove is fixedly connected with the outer magnetic ring left end cover, the first spiral arm torsion spring and the outer end cover at the left end, and a first screw sequentially penetrates through a first countersink of the outer end cover, a first peripheral through hole of the first spiral arm torsion spring and a second outer Zhou Tongkong of the outer magnetic ring left end cover to be fixed with a first threaded hole of the outer magnetic ring clamping groove; the outer magnetic ring clamping groove is fixedly connected with the outer magnetic ring right end cover, the second spiral arm torsion spring and the torsion spring fixing ring sleeved at the right end of the central shaft at the right end, and a second screw sequentially penetrates through a second countersunk hole of the torsion spring fixing ring, a third peripheral through hole of the second spiral arm torsion spring and a fourth outer Zhou Tongkong of the outer magnetic ring right end cover to be fixed with a second threaded hole of the outer magnetic ring clamping groove;
the inner magnetic ring left baffle is fixed on a first shaft shoulder of the central shaft, and a third screw penetrates through a third countersunk hole of the inner magnetic ring left baffle to be fixed on a third threaded hole of the inner magnetic ring clamping groove;
the inner magnetic ring right baffle is fastened by a third nut, and the third nut is in threaded fit with a second threaded section at the right end of the central shaft.
The longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity is also characterized in that: in the spiral arm torsion spring, the first spiral arm torsion spring and the second spiral arm torsion spring are elastic sheets with the same material and size parameters, are provided with a plurality of spiral arms which have the same spiral direction, are in an Archimedean spiral line shape, have rectangular cross sections and can twist and longitudinally deform, and are arranged at two ends of a central shaft according to opposite spiral directions, so that the vibration isolator can obtain linear torsion positive rigidity when being twisted along two different directions.
The longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity is also characterized in that:
the vibration isolator is enabled to meet the formulas (1) and (2) by selecting the dimension parameters of the outer magnetic ring, the inner magnetic ring, the first spiral arm torsion spring and the second spiral arm torsion spring, so that the vibration isolator has quasi-zero stiffness characteristics in the longitudinal direction and the torsion direction;
K r_m ＝ K r_s1 +K r_s2 (1)
K z_m ＝2K z_s (2)
wherein:
in K r_m Indicating the torsional negative stiffness of the magnetic spring;
in K r_s1 The torsional rigidity of the spiral arm torsion spring in the clockwise direction;
in K r_s2 The torsional rigidity of the spiral arm torsion spring in the anticlockwise direction;
in K z_m Representing the longitudinal negative stiffness of the magnetic spring;
in K z_s Representing the longitudinal stiffness of the spiral arm torsion spring.
The longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity is also characterized in that: an electromagnetic coil is arranged: the coil frames are fixedly arranged in outer magnetic ring latches at one-to-one intervals, coils are wound on the peripheries of the coil frames, outer magnetic shoes in the outer magnetic ring latches at corresponding positions are embedded in the coil frames, and an electromagnetic negative stiffness spring is formed by the electromagnetic coils, the outer magnetic rings and the inner magnetic rings; the magnitude and the direction of current in the coil are regulated in real time according to the torsional displacement and the longitudinal displacement of the vibration isolator, so that a magnetic field generated by the coil along the circumferential direction is overlapped with a magnetic field generated by the outer magnetic ring, and the longitudinal negative stiffness value and the torsional negative stiffness value of the negative stiffness spring are regulated to realize active vibration isolation.
The longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity is also characterized in that: except the outer magnetic ring, the inner magnetic ring and the coil, the rest structures are made of non-magnetic or weak magnetic materials.
Compared with the prior art, the invention has the positive effects that:
1. the electromagnetic negative stiffness spring and the spiral arm torsion spring are connected in parallel to form the quasi-zero stiffness mechanism, and the low-frequency longitudinal vibration, the low-frequency torsional vibration and the coupled vibration response of the low-frequency torsional vibration can be isolated through the quasi-zero stiffness mechanism under the excitation of longitudinal-torsional coupled low-frequency vibration.
2. When the coil is not electrified, the inner magnetic ring and the outer magnetic ring provide permanent magnetic longitudinal negative rigidity and permanent magnetic torsion negative rigidity; when the coil is electrified, the electromagnetic longitudinal negative rigidity and the electromagnetic torsional negative rigidity can be adjusted by changing the current magnitude and the direction of the coil, so that ideal vibration isolation performance is obtained, and active and passive integrated vibration isolation is realized.
3. The vibration isolator can obviously inhibit torsional vibration, longitudinal vibration and coupled vibration response of a shafting, and has a very wide vibration isolation frequency band.
4. The vibration isolator has compact structure and can be applied to precise micro instruments.
Drawings
Fig. 1 is a schematic structural diagram of a longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity.
FIGS. 2a, 2b and 2c are views of FIG. 1 taken along A-A; fig. 2a is a schematic diagram of magnetizing directions of the outer ring magnetic shoe and the inner ring magnetic shoe counterclockwise along the circumferential direction, fig. 2b is a schematic diagram of magnetizing directions of the outer ring magnetic shoe and the inner ring magnetic shoe clockwise along the circumferential direction, and fig. 2c is a schematic diagram of alternately changing magnetizing directions of the outer magnetic ring and the inner magnetic ring clockwise along the circumferential direction and anticlockwise along the circumferential direction.
FIGS. 3a and 3b are diagrams showing the energizing of a coil in the present invention; wherein, fig. 3a is a diagram showing the magnetic field direction of the magnetic field generated by the coil after the coil is energized anticlockwise in the circumferential direction, and fig. 3b is a diagram showing the magnetic field direction of the magnetic field generated by the coil after the coil is energized clockwise in the circumferential direction, wherein the dotted arrows represent the magnetic field direction of the magnetic field generated by the coil, and the solid arrows represent the magnetic field direction of the magnetic field generated by the magnetic shoe.
FIG. 4 is a schematic view of an outer end cap of the vibration isolator of the present invention;
FIG. 5a is a schematic view of a first helical arm torsion spring in the vibration isolator of the present invention;
FIG. 5b is a schematic view of a second helical arm torsion spring of the present invention;
fig. 6a is a schematic view of a left end cap of an outer magnetic ring in a vibration isolator according to the present invention;
fig. 6b is a schematic view of a right end cap of an outer magnetic ring in the vibration isolator of the present invention;
fig. 7 is a schematic diagram of an outer magnetic ring clamping groove in the vibration isolator of the present invention;
FIG. 8 is a schematic view of the torsion spring retaining ring of the vibration isolator of the present invention;
figure 9 is a schematic view of the central axis of the vibration isolator of the present invention;
fig. 10 is a schematic view of an inner magnetic ring slot in the vibration isolator of the present invention;
FIG. 11 is a schematic view of a left baffle of a magnetic ring in the isolator of the present invention;
FIG. 12 is a torque versus rotational displacement graph of a helical arm torsion spring in the vibration isolator of the present invention;
figure 13 is a graph of total rotational stiffness versus rotational displacement of the vibration isolator;
figure 14 is a graph of the total longitudinal stiffness versus longitudinal displacement of the vibration isolator;
FIG. 15a is a graph of an evaluation of torsional vibration isolation performance of the vibration isolator;
fig. 15b is a graph of a longitudinal vibration isolation performance evaluation of the vibration isolator.
Reference numerals in the drawings: the magnetic ring comprises an outer end cover 1, a fifth threaded section 1.2, a first countersunk hole 2, a first screw, a first spiral arm torsion spring 3, a first peripheral through hole 3.1, a first central hole 3.2, a first outer magnetic ring left end cover 4, a second outer Zhou Tongkong, a clamping groove 5, a third threaded section 5.1, a first threaded hole 5.2, a second threaded hole 5.3, a second outer magnetic ring 6, a first inner magnetic ring 7, a second outer magnetic ring right end cover 8, a fourth outer Zhou Tongkong 8.1, a second screw 9, a second spiral arm torsion spring 10, a third peripheral through hole 10.1, a second central hole 10.2, a torsion spring fixing collar 11, a second countersunk hole 11.1, a central shaft 12, a first threaded section 12.1, a first shaft shoulder 12.2, a second threaded section 12.3, a second threaded section 12.4, a second shoulder 12.4, a third threaded section 12.5, a fourth threaded section 12.6, a third threaded section 13, a third nut 14, a second nut 15, a right baffle plate 16, a third clamping groove 16, a third threaded section 16.1, a third threaded section 12.6, a fourth threaded section 12.6, a third nut 13, a second nut, a third inner magnetic ring 16, a third inner magnetic ring, a third threaded coil 18, a third inner magnetic ring 18, a third threaded section 18.1, a third spiral arm, a third threaded section 18.2, a third spiral arm, a third threaded section, a third coil 18.1, a third spiral coil, a third spiral frame, a third threaded hole 18, a third spiral frame, a fourth inner coil 1 and a third spiral frame.
Detailed Description
As shown in fig. 1, the longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity in the present embodiment is used for power transmission between the outer end cover 1 and the central shaft 12, and isolates disturbance torque and disturbance longitudinal force; a magnetic spring and a spiral arm torsion spring are arranged on the central shaft 12 in parallel; the magnetic spring is a negative stiffness spring with longitudinal negative stiffness and torsional negative stiffness, which is formed by an outer magnetic ring 6 and an inner magnetic ring 7 which are coaxially arranged on a central shaft 12 and can rotate relatively; the inner magnetic ring 7 is fixedly connected with the central shaft 12, and the outer magnetic ring 6 is positioned at the periphery of the inner magnetic ring 7; the spiral arm torsion spring is a positive stiffness spring with longitudinal positive stiffness and torsional positive stiffness, which is composed of a first spiral arm torsion spring 3 and a second spiral arm torsion spring 10 arranged at two ends of a central shaft 12; the first spiral arm torsion spring 3 and the second spiral arm torsion spring 10 are fixedly sleeved on the central shaft 12 through central holes and fixedly connected with the outer magnetic ring 6 through peripheral through holes. The negative stiffness spring and the positive stiffness spring which are arranged in parallel are utilized to enable the vibration isolator to obtain high static stiffness and low dynamic stiffness characteristics in the longitudinal direction and the torsion direction, so that the longitudinal stiffness and the torsion stiffness of a static balance position are reduced, and the longitudinal and torsion coupling low-frequency vibration isolation is realized.
In specific implementation, the corresponding technical measures also comprise:
as shown in fig. 2a, 2b and 2c, an outer magnetic ring 6 in the magnetic spring is formed by arranging a plurality of rubidium-iron-boron outer ring magnetic shoes which are magnetized in a circumferential direction, each outer ring magnetic shoe is clamped and fixed with an outer magnetic ring clamping tooth 5.1 on the inner wall of an outer magnetic ring clamping groove 5, and two ends of the outer magnetic ring 6 are respectively fastened by an outer magnetic ring left end cover 4 and an outer magnetic ring right end cover 8; the inner magnetic ring 7 in the magnetic spring is formed by arranging a plurality of rubidium-iron-boron inner ring magnetic shoes which are magnetized in a circumferential direction, each inner ring magnetic shoe is mutually clamped and fixed with the inner magnetic ring clamping teeth 16.2 on the inner wall of the inner magnetic ring clamping groove 16, and two ends of the inner magnetic ring 7 are respectively fastened by the inner magnetic ring left baffle 18 and the inner magnetic ring right baffle 15; the outer ring magnetic shoes and the inner ring magnetic shoes are equal in number, in the magnetic springs at the balance positions, the magnetizing directions of the outer ring magnetic shoes and the inner ring magnetic shoes at the corresponding radial positions are the same, and the sector angles are centered with the longitudinal heights;
setting the magnetizing directions of adjacent outer ring magnetic shoes to be the same;
or the magnetizing directions of the adjacent outer ring magnetic shoes are set to be opposite, the number of the outer ring magnetic shoes is 2N, and N is an integer;
as can be seen from the magnetic charge model, when the magnetizing directions of the outer ring magnetic shoes and the inner ring magnetic shoes in the outer magnetic ring 6 and the inner magnetic ring 7 are the same, the magnetic charge on the circumferential section of each outer ring magnetic shoe in the outer magnetic ring 6 is opposite to the magnetic charge on the circumferential section of the adjacent outer ring magnetic shoe, so that the magnetic charge density between the adjacent outer ring magnetic shoes is reduced, the magnetic field generated by the outer ring magnetic shoes is weakened, and the magnetic force and the magnetic moment born by the inner magnetic ring 7 are obviously reduced; when the magnetizing directions of adjacent outer (inner) magnetic shoes in the outer magnetic ring 6 and the inner magnetic ring 7 are opposite, the magnetic charge on the circumferential section of each outer magnetic shoe in the outer magnetic ring 6 is the same as the magnetic charge on the circumferential section of the adjacent outer magnetic shoe, so that the magnetic charge density between the adjacent outer magnetic shoes is increased, the superposition of magnetic fields generated by the outer magnetic shoes is enhanced, and the magnetic force and the magnetic moment born by the inner magnetic ring 7 are obviously increased; the magnetizing directions of the adjacent outer (inner) magnetic shoes in the outer magnetic ring 6 and the inner magnetic ring 7 are opposite, so that the magnetic shoe has larger magnetic negative rigidity, the interval of the magnetic negative rigidity is larger, and the outer ring magnetic shoes and the inner ring magnetic shoes in the outer magnetic ring 6 and the inner magnetic ring 7 are more convenient to install due to the mutual attraction between the adjacent inner (outer) ring magnetic shoes in the same magnetizing direction.
As shown in fig. 1, 4, 5a, 5b, 6a, 6b, 7, 8 and 9, the first spiral arm torsion spring 3 is sleeved at the left end of the central shaft 12 by a first central hole 3.2, and is fixed on a first shaft shoulder 12.2 of the central shaft 12 by a first nut 19 by a first thread section 12.1 on the central shaft 12;
the second spiral arm torsion spring 10 is sleeved at the right end of the central shaft 12 through a second central hole 10.2, and is fixed on a second shoulder 12.4 of the central shaft 12 through a third threaded section 12.5 of the central shaft 12 by a second nut 13;
the outer magnetic ring clamping groove 5 is fixedly connected with the outer magnetic ring left end cover 4, the first spiral arm torsion spring 3 and the outer end cover 1 at the left end, and is formed by sequentially penetrating a first countersunk hole 1.2 of the outer end cover 1, a first peripheral through hole 3.1 of the first spiral arm torsion spring 3 and a second outer Zhou Tongkong 4.1.1 of the outer magnetic ring left end cover 4 through a first screw hole 5.2 of the outer magnetic ring clamping groove 5 through a first screw 2; the outer magnetic ring clamping groove 5 is fixedly connected with the outer magnetic ring right end cover 8, the second spiral arm torsion spring 10 and the torsion spring fixing ring 11 sleeved at the right end of the central shaft 12 at the right end, and is formed by sequentially penetrating a second countersunk hole 11.1 of the torsion spring fixing ring 11, a third peripheral through hole 10.1 of the second spiral arm torsion spring 10 and a fourth outer Zhou Tongkong 8.1.1 of the outer magnetic ring right end cover 8 through a second screw 9 to be fixed with a second threaded hole 5.3 of the outer magnetic ring clamping groove 5;
as shown in fig. 8, 9, 10 and 11, the inner magnetic ring left baffle 18 is fixed to the first shoulder 12.2 of the central shaft 12, and is fixed to the third threaded hole 16.1 of the inner magnetic ring clamping groove 16 by a third screw 17 passing through the third countersunk hole 18.1 of the inner magnetic ring left baffle 18;
the inner magnetic ring right baffle 15 is fastened by a third nut 14, and the third nut 14 is in threaded fit with the second threaded section 12.3 at the right end of the central shaft 12.
As shown in fig. 5a and 5b, in the spiral arm torsion springs, the first spiral arm torsion spring 3 and the second spiral arm torsion spring 10 are elastic sheets with the same material and dimension parameters, and are provided with a plurality of spiral arms which have the same spiral direction, are in an archimedes spiral shape, have rectangular cross sections and can twist and longitudinally deform;
as shown in fig. 12, when the torsion spring is torsionally deformed clockwise, the spiral arm is pressed, and the torsional rigidity gradually increases; when the torsion spring is deformed in a counterclockwise torsion mode, the spiral arm is stretched, and the torsional rigidity is gradually reduced; the first spiral arm torsion spring 3 and the second spiral arm torsion spring 10 are arranged at two ends of the central shaft 12 in opposite directions according to the rotation direction, so that the vibration isolator can obtain linear torsion positive rigidity when being twisted in two different directions;
the vibration isolator meets the formulas 1 and 2 by selecting the dimensional parameters of the outer magnetic ring 6, the inner magnetic ring 7, the first spiral arm torsion spring 3 and the second spiral arm torsion spring 10, so that the vibration isolator has quasi-zero stiffness characteristics in the longitudinal direction and the torsion direction;
K r_m ＝ K r_s1 +K r_s2 (1)
K z_m ＝2K z_s (2)
wherein:
in K r_m Indicating the torsional negative stiffness of the magnetic spring;
in K r_s1 The torsional rigidity of the spiral arm torsion spring in the clockwise direction;
in K r_s2 The torsional rigidity of the spiral arm torsion spring in the anticlockwise direction;
in K z_m Representing the longitudinal negative stiffness of the magnetic spring;
in K z_s Representing the longitudinal stiffness of the helical arm torsion spring;
as shown in fig. 2a, 2b, 2c, 3a and 3b, in order to achieve active vibration isolation, a solenoid is provided: the coil frameworks 21 are fixedly arranged in the outer magnetic ring clamping teeth 5.1 at one-to-one intervals, the coils 20 are wound on the peripheries of the coil frameworks 21, outer ring magnetic shoes in the outer magnetic ring clamping teeth 5.1 at corresponding positions are embedded into the coil frameworks 21, and an electromagnetic negative stiffness spring is formed by the electromagnetic coils, the outer magnetic rings 6 and the inner magnetic rings 7; the magnitude and direction of current in the coil 20 are adjusted in real time according to the torsional displacement and longitudinal displacement of the vibration isolator, so that the magnetic field generated by the coil 20 along the circumferential direction is overlapped with the magnetic field generated by the outer magnetic ring 6, and the longitudinal negative stiffness value and the torsional negative stiffness value of the negative stiffness spring are adjusted, thereby realizing active vibration isolation.
As shown in fig. 4 and 9, the fifth thread segment 1.1 of the outer end cap 1 and the fourth thread segment 12.6 of the central shaft 12 are used for connecting a driving shaft and a driven shaft.
Except for the outer magnetic ring 6, the inner magnetic ring 7 and the coil 20, the rest structures are made of non-magnetic or weak magnetic materials.
The working principle of the invention is as follows: the outer magnetic ring 6, the inner magnetic ring 7 and the coil 20 form a high static stiffness low dynamic stiffness structure with the first spiral arm torsion spring 3 and the second spiral arm torsion spring 10 when the central shaft 12 moves longitudinally and torsionally relative to the outer end cover 1, when the coil 20 is not energized, the magnetic torque and the longitudinal magnetic force of the magnetic spring are small in a small rotation displacement and small longitudinal displacement range near the balance position, and the total dynamic stiffness is basically zero as shown in fig. 13 and 14, and at the moment, the transmitted torque and the longitudinal force are provided by the first spiral arm torsion spring 3 and the second spiral arm torsion spring 10 only; when the coil 20 is electrified, the magnitude and the direction of the magnetic field generated by the coil 20 can be controlled by adjusting the magnitude and the direction of the current of the coil 20, so that the negative stiffness characteristic with longer stroke and larger amplitude can be obtained, and the high static stiffness and low dynamic stiffness characteristics can be realized in a large rotational displacement range and a large longitudinal displacement range near the balance position. As shown in fig. 15a and 15b, the longitudinal vibration isolation transmissibility and torsional vibration isolation transmissibility of the vibration isolator and its corresponding linear vibration isolator (i.e., the outer magnet ring 6 is eliminated, the inner magnet ring 7, the coil 20) have several advantages: 1. the vibration isolation frequency of the torsional movement and the longitudinal movement is reduced by more than 50 percent; 2. the torsional vibration isolation efficiency and the longitudinal vibration isolation efficiency in the low frequency region are far superior to those of the linear vibration isolator. Therefore, the present invention has the property of isolating low-frequency longitudinal vibration and low-frequency torsional vibration.
Claims (8)
1. A longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity is characterized in that:
the vibration isolator is used for power transmission between the outer end cover (1) and the central shaft (12) and isolating interference torque and interference longitudinal force; a magnetic spring and a spiral arm torsion spring are arranged on the central shaft (12) in parallel;
the magnetic spring is a negative stiffness spring with longitudinal negative stiffness and torsional negative stiffness, and the negative stiffness spring is composed of an outer magnetic ring (6) and an inner magnetic ring (7) which are coaxially arranged on a central shaft (12) and can rotate relatively; the inner magnetic ring (7) is fixedly connected with the central shaft (12), and the outer magnetic ring (6) is positioned at the periphery of the inner magnetic ring (7);
the spiral arm torsion spring is a positive stiffness spring with longitudinal positive stiffness and torsional positive stiffness, and the positive stiffness spring is composed of a first spiral arm torsion spring (3) and a second spiral arm torsion spring (10) which are arranged at two ends of a central shaft (12); the first spiral arm torsion spring (3) and the second spiral arm torsion spring (10) are fixedly sleeved on the central shaft (12) through central holes and fixedly connected with the outer magnetic ring (6) through peripheral through holes;
the negative stiffness spring and the positive stiffness spring which are arranged in parallel are utilized to enable the vibration isolator to obtain high static stiffness and low dynamic stiffness characteristics in the longitudinal direction and the torsion direction, so that the longitudinal stiffness and the torsion stiffness of a static balance position are reduced, and the longitudinal and torsion coupling low-frequency vibration isolation is realized.
2. The electromagnetic negative stiffness based longitudinal and torsional coupling low frequency vibration isolator of claim 1, wherein:
the outer magnetic ring (6) in the magnetic spring is formed by arranging a plurality of rubidium-iron-boron outer ring magnetic shoes which are magnetized in a circumferential direction, each outer ring magnetic shoe is clamped and fixed with an outer magnetic ring clamping tooth (5.1) on the inner wall of an outer magnetic ring clamping groove (5), and two ends of the outer magnetic ring (6) are respectively fastened by an outer magnetic ring left end cover (4) and an outer magnetic ring right end cover (8);
the inner magnetic ring (7) in the magnetic spring is formed by arranging a plurality of rubidium-iron-boron inner ring magnetic shoes which are magnetized in a circumferential direction, each inner ring magnetic shoe is mutually clamped and fixed with inner magnetic ring clamping teeth (16.2) on the inner wall of an inner magnetic ring clamping groove (16), and two ends of the inner magnetic ring (7) are respectively fastened by an inner magnetic ring left baffle (18) and an inner magnetic ring right baffle (15);
the outer ring magnetic shoes and the inner ring magnetic shoes are equal in number, and in the magnetic springs at the balance positions, the outer ring magnetic shoes and the inner ring magnetic shoes at the corresponding radial positions are magnetized in the same direction, and the sector angles are centered with the longitudinal heights.
3. The electromagnetic negative stiffness based longitudinal and torsional coupling low frequency vibration isolator of claim 2, wherein:
setting the magnetizing directions of adjacent outer ring magnetic shoes to be the same;
or the magnetizing directions of the adjacent outer ring magnetic shoes are set to be opposite, the number of the outer ring magnetic shoes is 2N, and N is an integer.
4. The electromagnetic negative stiffness based longitudinal and torsional coupling low frequency vibration isolator of claim 2, wherein:
the first spiral arm torsion spring (3) is sleeved at the left end of the central shaft (12) through a first central hole (3.2), and is fixed on a first shaft shoulder (12.2) of the central shaft (12) through a first nut (19) by utilizing a first threaded section (12.1) on the central shaft (12);
the second spiral arm torsion spring (10) is sleeved at the right end of the central shaft (12) through a second central hole (10.2), and is fixed on a second shoulder (12.4) of the central shaft (12) through a third threaded section (12.5) of the central shaft (12) by a second nut (13);
the outer magnetic ring clamping groove (5) is fixedly connected with the outer magnetic ring left end cover (4), the first spiral arm torsion spring (3) and the outer end cover (1) at the left end, and a first screw (2) sequentially penetrates through a first countersunk hole (1.2) of the outer end cover (1), a first peripheral through hole (3.1) of the first spiral arm torsion spring (3) and a second outer Zhou Tongkong (4.1) of the outer magnetic ring left end cover (4) to be fixed with a first threaded hole (5.2) of the outer magnetic ring clamping groove (5); the outer magnetic ring clamping groove (5) is fixedly connected with the outer magnetic ring right end cover (8), the second spiral arm torsion spring (10) and the torsion spring fixing ring (11) sleeved at the right end of the central shaft (12) at the right end, and a second screw (9) sequentially penetrates through a second countersunk hole (11.1) of the torsion spring fixing ring (11), a third peripheral through hole (10.1) of the second spiral arm torsion spring (10) and a fourth outer Zhou Tongkong (8.1) of the outer magnetic ring right end cover (8) to be fixed with a second threaded hole (5.3) of the outer magnetic ring clamping groove (5);
the inner magnetic ring left baffle (18) is fixed on a first shaft shoulder (12.2) of the central shaft (12), and a third screw (17) penetrates through a third countersunk hole (18.1) of the inner magnetic ring left baffle (18) to be fixed on a third threaded hole (16.1) of the inner magnetic ring clamping groove (16);
the inner magnetic ring right baffle (15) is fastened by a third nut (14), and the third nut (14) is in threaded fit with a second threaded section (12.3) at the right end of the central shaft (12).
5. The electromagnetic negative stiffness based longitudinal and torsional coupling low frequency vibration isolator of claim 1, wherein:
in the spiral arm torsion spring, the first spiral arm torsion spring (3) and the second spiral arm torsion spring (10) are elastic sheets with the same material and size parameters, and are provided with a plurality of spiral arms which are identical in rotation direction, are in an Archimedean spiral line shape, are rectangular in section and can twist and longitudinally deform, and the first spiral arm torsion spring (3) and the second spiral arm torsion spring (10) are arranged at two ends of a central shaft (12) according to opposite rotation directions, so that the vibration isolator can obtain linear torsion positive rigidity when being twisted along two different directions.
6. The electromagnetic negative stiffness based longitudinal and torsional coupling low frequency vibration isolator of claim 1, wherein:
the vibration isolator meets the formulas (1) and (2) by selecting the dimensional parameters of the outer magnetic ring (6), the inner magnetic ring (7), the first spiral arm torsion spring (3) and the second spiral arm torsion spring (10), so that the vibration isolator has quasi-zero stiffness characteristics in the longitudinal direction and the torsion direction;
K r_m ＝ K r_s1 +K r_s2 (1)
K z_m ＝2K z_s (2)
wherein:
in K r_m Indicating the torsional negative stiffness of the magnetic spring;
in K r_s1 The torsional rigidity of the spiral arm torsion spring in the clockwise direction;
in K r_s2 The torsional rigidity of the spiral arm torsion spring in the anticlockwise direction;
in K z_m Representing the longitudinal negative stiffness of the magnetic spring;
in K z_s Representing the longitudinal stiffness of the spiral arm torsion spring.
7. The electromagnetic negative stiffness based longitudinal and torsional coupling low frequency vibration isolator of claim 1, wherein:
an electromagnetic coil is arranged: the coil frameworks (21) are fixedly arranged in outer magnetic ring latches (5.1) at one-to-one intervals, coils (20) are wound on the peripheries of the coil frameworks (21), outer magnetic shoes in the outer magnetic ring latches (5.1) at corresponding positions are embedded into the coil frameworks (21), and an electromagnetic negative stiffness spring is formed by an electromagnetic coil, an outer magnetic ring (6) and an inner magnetic ring (7); the magnitude and the direction of current in the coil (20) are regulated in real time according to the torsional displacement and the longitudinal displacement of the vibration isolator, so that a magnetic field generated by the coil (20) along the circumferential direction is overlapped with a magnetic field generated by the outer magnetic ring (6), and the longitudinal negative stiffness value and the torsional negative stiffness value of the negative stiffness spring are regulated to realize active vibration isolation.
8. The electromagnetic negative stiffness based longitudinal and torsional coupling low frequency vibration isolator of claim 1, wherein: except for the outer magnetic ring (6), the inner magnetic ring (7) and the coil (20), the rest structures are made of non-magnetic or weak magnetic materials.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311005737.8A CN116989096A (en) | 2023-08-10 | 2023-08-10 | Longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311005737.8A CN116989096A (en) | 2023-08-10 | 2023-08-10 | Longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity |
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| Publication Number | Publication Date |
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| CN202311005737.8A Pending CN116989096A (en) | 2023-08-10 | 2023-08-10 | Longitudinal and torsional coupling low-frequency vibration isolator based on electromagnetic negative rigidity |
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