CN112709781B - Torsion quasi-zero stiffness vibration isolator with adjustable balance position and method - Google Patents

Torsion quasi-zero stiffness vibration isolator with adjustable balance position and method Download PDF

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Publication number
CN112709781B
CN112709781B CN202011639669.7A CN202011639669A CN112709781B CN 112709781 B CN112709781 B CN 112709781B CN 202011639669 A CN202011639669 A CN 202011639669A CN 112709781 B CN112709781 B CN 112709781B
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magnetic ring
vibration isolator
balance position
quasi
torsional
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CN112709781A (en
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李学勇
张硕
张春松
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Shandong University
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Shandong University
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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
    • F16F15/12—Suppression of vibrations in rotating systems by making use of members moving with the system using elastic members or friction-damping members, e.g. between a rotating shaft and a gyratory mass mounted thereon
    • F16F15/131—Suppression of vibrations in rotating systems by making use of members moving with the system using elastic members or friction-damping members, e.g. between a rotating shaft and a gyratory mass mounted thereon the rotating system comprising two or more gyratory masses
    • F16F15/133—Suppression of vibrations in rotating systems by making use of members moving with the system using elastic members or friction-damping members, e.g. between a rotating shaft and a gyratory mass mounted thereon the rotating system comprising two or more gyratory masses using springs as elastic members, e.g. metallic springs
    • F16F15/1336—Leaf springs, e.g. radially extending
    • 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
    • F16F15/12—Suppression of vibrations in rotating systems by making use of members moving with the system using elastic members or friction-damping members, e.g. between a rotating shaft and a gyratory mass mounted thereon
    • F16F15/131—Suppression of vibrations in rotating systems by making use of members moving with the system using elastic members or friction-damping members, e.g. between a rotating shaft and a gyratory mass mounted thereon the rotating system comprising two or more gyratory masses
    • F16F15/13121—Suppression of vibrations in rotating systems by making use of members moving with the system using elastic members or friction-damping members, e.g. between a rotating shaft and a gyratory mass mounted thereon the rotating system comprising two or more gyratory masses characterised by clutch arrangements, e.g. for activation; integrated with clutch members, e.g. pressure member
    • 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
    • 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
    • F16F2228/00—Functional characteristics, e.g. variability, frequency-dependence
    • F16F2228/06—Stiffness
    • 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
    • F16F2230/00—Purpose; Design features
    • F16F2230/0005—Attachment, e.g. to facilitate mounting onto confer adjustability

Abstract

The invention discloses a torsional quasi-zero stiffness vibration isolator with adjustable balance position and a method thereof, wherein the torsional quasi-zero stiffness vibration isolator comprises an outer shell, wherein a positive stiffness element, a negative stiffness element, a balance position adjusting mechanism and a clutch mechanism are arranged in the outer shell; the positive stiffness element comprises a semicircular piece and a reed, the semicircular piece is provided with a bulge along the axial direction, and a gap is formed between the bulges of the semicircular piece and the bulge of the semicircular piece for the reed to extend into; the negative stiffness element comprises an outer magnetic ring and an inner magnetic ring, an air gap is formed between the outer magnetic ring and the inner magnetic ring, the inner magnetic ring is connected with a balance position adjusting mechanism, and the balance position adjusting mechanism can drive the inner magnetic ring to rotate so as to adjust the balance position of the inner magnetic ring and the balance position of the outer magnetic ring; the balance position adjusting mechanism is connected with the clutch mechanism, an electromagnet in the clutch mechanism and an armature iron can be attracted or separated, positive rigidity and negative rigidity can be connected in parallel when attraction is carried out, and the balance position can be adjusted after separation. The vibration isolator can adapt to the working loads with different sizes and in the positive and negative rotation directions, and effectively improves the vibration isolation performance and the application range of the vibration isolator.

Description

Torsion quasi-zero stiffness vibration isolator with adjustable balance position and method
Technical Field
The invention belongs to the technical field of torsional vibration isolation, and particularly relates to a torsional quasi-zero stiffness vibration isolator with adjustable balance position and a method.
Background
The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.
Rotary machines have wide application in various industrial fields. Torsional vibrations, a ubiquitous dynamic phenomenon in rotating mechanical systems, can interfere with mechanical equipment, particularly sensitive low frequency vibrations. The amplitude of low-frequency vibration in the machining process is generally large, which not only affects the machining precision and the working efficiency, but also aggravates the abrasion of precision parts inside mechanical equipment and reduces the service life of the precision parts, and meanwhile, severe vibration can seriously harm the physical health of workers, so that the inhibition or isolation of the low-frequency vibration in the working environment is very important.
Vibration isolation techniques are often preferred when dealing with the problem of unwanted vibrations. The vibration isolator designed based on the quasi-zero stiffness principle has the characteristics of high static stiffness and low dynamic stiffness, and not only has high bearing capacity, but also can effectively isolate low-frequency vibration. At present, the quasi-zero stiffness technology has been applied to the field of isolating low-frequency torsional vibrations.
At present, related scholars propose a torsional quasi-zero stiffness vibration isolator, in order to eliminate a vibration isolator or a coupling with low-frequency torsional vibration of a shafting, the mode only has a good low-frequency vibration isolation effect on a fixed design load, and when the load changes, the vibration isolation effect can be obviously reduced. In addition, some students propose a quasi-zero stiffness coupling for isolating torsional vibration, the mode only has a vibration isolation effect on fixed design load, the coupling can only work under fixed steering, and if reverse load is input, the magnetic shoes of the inner magnetic ring and the outer magnetic ring deviate from a balance position, so that the system cannot reach a quasi-zero stiffness state, and the vibration isolation effect is seriously influenced. Some researchers have proposed torsional quasi-zero stiffness vibration isolators, which improve the vibration isolation effect to some extent by adjusting the negative stiffness, but basically only act on a fixed load, and once the load changes greatly, the vibration isolators deviate from the quasi-zero stiffness state to a greater extent, thereby affecting the vibration isolation effect.
In summary, the existing vibration isolator can only perform the vibration isolation function on the load in a fixed or small variation range, and can not achieve the good vibration isolation effect when the load is greatly changed.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a torsional quasi-zero stiffness vibration isolator with an adjustable balance position and a method thereof.
In order to achieve the purpose, the invention is realized by the following technical scheme:
in a first aspect, an embodiment of the present invention provides a torsional quasi-zero stiffness vibration isolator with an adjustable balance position, including an outer shell, wherein a positive stiffness element and a negative stiffness element are arranged in the outer shell; the positive stiffness element comprises two semicircular pieces and two reeds, wherein the semicircular pieces are arranged oppositely, the reeds are arranged up and down, the semicircular pieces are provided with protrusions along the axial direction, and gaps are formed between the protrusions of the semicircular pieces for the reeds to extend into; the negative stiffness element comprises an outer magnetic ring and an inner magnetic ring, an air gap is formed between the outer magnetic ring and the inner magnetic ring, the inner magnetic ring is connected with a balance position adjusting mechanism, and the balance position adjusting mechanism can drive the inner magnetic ring to rotate so as to adjust the balance position of the inner magnetic ring and the balance position of the outer magnetic ring.
As a further technical scheme, the balance position adjusting mechanism comprises an inner shell, an outer magnetic ring is fixed on the inner wall of the outer shell, an inner magnetic ring is fixed on the outer wall of the inner shell, the inner shell is connected with a power device, and the power device drives the inner shell to rotate.
As a further technical scheme, one end of the outer shell is connected with the input shaft, the end cover connected with the other end of the outer shell is provided with a shaft hole for the output shaft to extend out, and the reed is fixedly connected with the output shaft.
As a further technical scheme, the end part of the reed is fixed between two clamping rings, and the clamping rings are fixedly connected with the output shaft; the matching position of the output shaft and the snap ring is set to be a polygonal structure, and the matching position of the inner wall of the snap ring and the output shaft is set to be a plane.
As a further technical scheme, the balance position adjusting mechanism is connected with a clutch mechanism, the clutch mechanism comprises an electromagnet fixedly connected with the end part of the inner shell, the electromagnet and the armature can be attracted or separated, positive rigidity and negative rigidity can be connected in parallel when the electromagnet and the armature are attracted, and the balance position can be adjusted after the electromagnet and the armature are separated.
As a further technical scheme, the clutch mechanism further comprises a spline shaft, the end part of the spline shaft is connected with the spline housing through a spline, the armature is fixedly connected with the spline housing, and the spline housing can move axially along the spline shaft.
As a further technical scheme, the spline shaft is connected with the output shaft, and a bearing is arranged between the spline shaft and the inner shell; the periphery of the spline shaft is provided with a baffle plate, and a spring is arranged between the baffle plate and the spline housing.
As a further technical scheme, the output shaft and the end cover are also fixedly provided with a rotary encoder.
As a further technical scheme, the outer magnetic ring and the inner magnetic ring both include a plurality of magnetic tiles, the number of the magnetic tiles of the outer magnetic ring is the same as that of the magnetic tiles of the inner magnetic ring, the magnetic tiles of the outer magnetic ring and the magnetic tiles of the inner magnetic ring are arranged in a one-to-one correspondence manner, the magnetizing directions of the corresponding magnetic tiles of the outer magnetic ring and the inner magnetic ring are opposite, the magnetizing directions of the magnetic tiles of the inner magnetic ring and the outer magnetic ring face to the radial direction, and the magnetizing directions of the magnetic tiles of the outer magnetic ring and the inner magnetic ring are changed alternately along the radial direction.
The working principle of the vibration isolator provided by the invention is as follows:
when the vibration isolator is not in a working state, the reed is not bent and deformed, and torque is not transmitted; when the vibration isolator is in a stable working state, the reed is contacted with the semi-circular piece and is bent and deformed, so that the output shaft and the input shaft (outer shell) generate a relative rotation angle theta0Positive rigidity K of reed torsionrA torsional moment of Krθ0At the moment, the magnetic shoes of the outer magnetic ring and the inner magnetic ring are in a positive alignment state, the magnetic moment generated by the magnetic spring is zero, but great negative stiffness K can be generatedmBy reasonably designing the geometric parameters of the semicircular piece, the reed, the outer magnetic ring and the inner magnetic ring, the negative stiffness K generated by the magnetic spring can be ensuredmPositive stiffness K with reedrThe mutual offset makes the total rigidity of the vibration isolator approximate to zero, thereby realizing the effective isolation of the low-frequency torsional vibration; the working load of the vibration isolator is provided by the torque K provided by the reedrθ0Therefore, the bearing capacity is higher.
When a coil of an electromagnet in the clutch mechanism is not electrified, the electromagnet is separated from an armature, and the inner shell can rotate relative to the spline shaft due to the existence of the first bearing; when the coil is electrified, the electromagnet generates a magnetic field to attract the armature mutually, the spline housing overcomes the action of spring force to generate axial motion relative to the spline shaft, finally, the electromagnet is attracted with the armature, and the inner shell and the spline shaft keep synchronous motion.
When the vibration isolator is in a stable working state, the torsional positive stiffness generated by the reed and the negative stiffness generated by the magnetic spring are mutually offset, so that the total stiffness of the system reaches a quasi-zero state, and low-frequency vibration is effectively isolated. However, the quasi-zero stiffness state only corresponds to a fixed load torque, and when the magnitude or direction of the system load changes, the vibration isolator deviates from a balance position, and the vibration isolation effect is obviously reduced or even fails. At the moment, the invention can convert the relative angular displacement generated by the output shaft relative to the end cover (outer shell) into a corresponding electric pulse signal to be output through the rotary encoder, and the coil of the electromagnet is controlled to be powered off and the electromagnet is separated from the armature through the controller; then the controller sends a pulse signal to the power device, the motor is controlled to rotate by a corresponding angle in the same axial direction, the magnetic shoes of the inner magnetic ring and the outer magnetic ring are enabled to return to the opposite state (balance position) again, at the moment, the coil of the electromagnet is electrified, the electromagnet and the armature are mutually attracted, the inner shell and the spline shaft keep synchronous motion, and the vibration isolator reaches the quasi-zero rigidity state again. Compared with the quasi-zero stiffness state before adjustment, the positive stiffness generated by the reed and the negative stiffness generated by the magnetic spring are not changed, but the balance position of the vibration isolator is changed, so that the load torque transmitted by the reed is different from that before adjustment and corresponds to the changed load. Therefore, the device can adapt to different loads, and can still effectively isolate low-frequency torsional vibration after the system load is changed.
In a second aspect, the embodiment of the invention further provides an operating method of the torsional quasi-zero stiffness vibration isolator, which includes the following steps:
when the vibration isolator is not in a working state, the reed is not bent and deformed, and torque is not transmitted;
when the vibration isolator is in a stable working state, the reed is in contact with the semi-circular piece and is bent and deformed, the positive torsional rigidity generated by the reed and the negative rigidity generated by the inner magnetic ring and the outer magnetic ring are mutually offset, and the vibration isolator reaches a quasi-zero rigidity state to realize effective isolation of low-frequency torsional vibration;
when the size or the direction of the load changes, the vibration isolator deviates from a balance position, the inner magnetic ring is driven to rotate through the balance position adjusting mechanism, the inner magnetic ring and the outer magnetic ring reach the next balance position, the vibration isolator reaches a quasi-zero rigidity state again, and low-frequency torsional vibration is still effectively isolated after the load changes.
The beneficial effects of the above-mentioned embodiment of the present invention are as follows:
the vibration isolator has the advantages that the reed bending deformation can generate positive torsional rigidity, the inner magnetic ring and the outer magnetic ring can generate negative rigidity, the balance position adjusting mechanism can adjust the balance position of the negative rigidity element, so that the quasi-zero rigidity state can be achieved under different loads and positive and negative rotation directions, high static rigidity and low dynamic rigidity are realized near the working position, the torque can be effectively transmitted, the low-frequency torsional vibration can be well isolated, and the vibration isolation frequency band is widened.
When the load changes, the balance position of the negative stiffness element is adjusted by driving the inner magnetic ring to rotate through the balance position adjusting mechanism, and the positive stiffness and the negative stiffness are connected in parallel by combining the inner shell and the output shaft into a whole through electrifying the electromagnet coil in the clutch mechanism, so that the quasi-zero stiffness is realized, the structure is compact, and the control is simple.
When the vibration isolator starts to work or the load torque changes, the output shaft and the shell rotate relatively to cause the magnetic shoes of the inner magnetic ring and the outer magnetic ring to deviate, at the moment, the inner shell is driven by the power device to rotate relative to the output shaft, the magnetic shoes of the inner magnetic ring and the outer magnetic ring can be aligned again, the working state is not limited by load steering, and the adjustment is flexible. The vibration isolator can adapt to the working loads with different sizes and in the positive and negative rotation directions, and effectively improves the vibration isolation performance and the application range of the vibration isolator.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
Figure 1 is a schematic view of a vibration isolator according to one or more embodiments of the present invention;
FIG. 2 is a cross-sectional view A-A of FIG. 1;
FIG. 3 is a schematic view of the output shaft in cooperation with a positive stiffness element or the like;
FIG. 4 is a schematic view of a negative stiffness element;
FIG. 5 is a schematic view of a balance position adjustment mechanism;
FIG. 6 is an enlarged partial view of the clutch mechanism;
FIG. 7 is a schematic view of the installation of a rotary encoder;
FIG. 8(a) is a schematic view showing the state of the reed and the magnetic spring when the equilibrium position is reached;
FIG. 8(b) is a schematic view showing the state of the reed and the magnetic spring at the time of deviating from the equilibrium position;
FIG. 9 is a graph of the torsional moment versus torsional angle of the spring plate and the magnetic spring;
FIG. 10 is a graph of the total stiffness versus torsion angle of the vibration isolator of the present invention;
in the figure: the mutual spacing or size is exaggerated to show the position of each part, and the schematic diagram is only used for illustration;
1 left shell, 2 right shell, 3 end covers, 4 output shafts, 5 semicircular pieces, 5-1 bulges, 6 reeds, 7 snap rings, 8 outer magnetic rings, 9 inner magnetic rings, 10 inner shells, 11 spline shafts, 12 first bearings, 13 power devices, 13-1 stepping motors, 13-2 planetary reducers, 14 first check rings, 15 locating rings, 16 electromagnets, 16-1 magnetic yokes, 16-2 coils, 17 armatures, 18 spline sleeves, 19 baffle plates, 20 springs, 21 rotary encoders, 21-1 reading head circuit boards, 21-2 coded discs, 22 second bearings and 23 second check rings.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an", and/or "the" are intended to include the plural forms as well, unless the invention expressly state otherwise, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;
for convenience of description, the words "up", "down", "left" and "right" in the present invention, if any, merely indicate correspondence with the directions of up, down, left and right of the drawings themselves, and do not limit the structure, but merely facilitate the description of the invention and simplify the description, rather than indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the invention.
The terms "mounted", "connected", "fixed", and the like in the present invention should be understood broadly, and for example, the terms "mounted", "connected", "fixed", and the like may be fixedly connected, detachably connected, or integrated; the two components can be connected mechanically or electrically, directly or indirectly through an intermediate medium, or connected internally or in an interaction relationship, and the terms used in the present invention should be understood as having specific meanings to those skilled in the art.
As introduced by the background art, the prior art has shortcomings, and in order to solve the technical problems, the invention provides a torsional quasi-zero stiffness vibration isolator with adjustable balance position and a method thereof, which can adapt to working loads with different sizes and directions and have good low-frequency vibration isolation performance.
In an exemplary embodiment of the invention, as shown in fig. 1, a torsional quasi-zero stiffness vibration isolator with adjustable balance position is provided, which comprises a left shell 1, a right shell 2, and a positive stiffness element, a negative stiffness element, a balance position adjusting mechanism and a clutch mechanism inside the shells.
Wherein, the left shell and the right shell are connected to form an outer shell; one side of the left shell 1 is provided with a shaft hole and a key slot which are connected with an input shaft; one side of the right shell 2 is connected with an end cover 3, a shaft hole is formed in the middle of the end cover 3, an output shaft 4 extends out of the outer shell, and a key groove is formed in the extending end of the output shaft 4; the left shell 1 and the right shell 2 are fixedly connected through bolts and nuts, and the right shell 2 and the end cover 3 are fixedly connected through screws.
A positive stiffness element is disposed within the right housing. As shown in fig. 2, the positive stiffness element comprises a semi-circular piece 5 and a leaf 6. The semicircular pieces are arranged in two numbers, the two semicircular pieces 5 are fixedly connected inside the right shell 2 through screws, the semicircular pieces are horizontally provided with semicircular columnar bulges 5-1 along the axial direction, and narrow gaps are formed between the bulges 5-1 of the two semicircular pieces 5 and used for the reeds 6 to stretch into.
The semicircular pieces are of semicircular annular structures, the two semicircular pieces are arranged oppositely, and the protrusions are arranged at the opposite positions of the two semicircular pieces.
As shown in fig. 3, the upper and lower reeds 6 are mounted between the left and right semicircular snap rings 7, and the two snap rings 7 are fixed on the output shaft 4 through bolts and nuts; the matching position of the output shaft and the snap ring is set to be a polygonal structure, the inner wall of the snap ring 7 and the surface of the output shaft 4 are both provided with partial planes, and the reed 6 and the output shaft 4 are ensured not to move relatively through forming connection.
The negative stiffness element is disposed within the left housing. As shown in fig. 4, the negative stiffness element comprises an outer magnetic ring 8 and an inner magnetic ring 9. A certain air gap is arranged between the outer magnetic ring 8 and the inner magnetic ring 9, and the outer magnetic ring 8 and the inner magnetic ring 9 form a magnetic spring; the outer magnetic ring 8 is fixed on the inner wall of the left shell 1, the inner magnetic ring 9 is fixed on the outer wall of the inner shell 10, the inner shell is arranged in the left shell, and the inner shell and the left shell are coaxially arranged.
In a further scheme, the outer magnetic ring 8 and the inner magnetic ring 9 are formed by combining a plurality of magnetic tiles, the number of the magnetic tiles of the outer magnetic ring 8 is the same as that of the magnetic tiles of the inner magnetic ring 9, the number of the magnetic tiles is 2N, N is an integer and is designed according to needs. The magnetic shoes of the outer magnetic ring and the inner magnetic ring are arranged in one-to-one correspondence, the magnetizing directions of the corresponding magnetic shoes of the outer magnetic ring and the inner magnetic ring are opposite, the magnetizing directions of the magnetic shoes of the inner magnetic ring and the outer magnetic ring face to the radial direction, and the magnetizing directions of the magnetic shoes of the outer magnetic ring and the inner magnetic ring are alternately changed along the radial direction, namely the magnetizing directions of the magnetic shoes of the adjacent outer magnetic ring are opposite, and the magnetizing directions of the magnetic shoes of the adjacent inner magnetic ring are opposite.
In a further development, the magnetic shoes of the outer magnetic ring 8 have an angular width in the circumferential direction which is slightly larger than the magnetic shoes of the inner magnetic ring 9.
As shown in fig. 5, the balance position adjusting mechanism includes an inner housing 10, a first bearing 12, a power unit 13, a first retainer ring 14, and a retainer ring 15. Wherein, the inner ring of the first bearing 12 is matched with the spline shaft 11, and the outer ring is matched with the inner shell 10; the power device 13 consists of a stepping motor 13-1 and a planetary reducer 13-2, is fixed at the left shaft end of the spline shaft 11 through bolts and nuts, and keeps synchronous rotation of a motor shaft and the inner shell 10 through key connection; first retaining ring 14 is installed on integral key shaft 11, and the inside right side of interior casing 10 is provided with position circle 15, and first retaining ring 14 realizes the axial positioning to first bearing with position circle 15, guarantees that interior casing 10 and integral key shaft 11 can only rotate relatively, can not be at axial relative movement.
As shown in fig. 6 and 7, the clutch mechanism includes a spline shaft 11, an electromagnet 16, an armature 17, a spline housing 18, a stopper plate 19, a spring 20, and a rotary encoder 21. Wherein the spline shaft 11 is connected with the output shaft 4 through threads and moves synchronously; the electromagnet 16 consists of a magnet yoke 16-1 and a coil 16-2, and the electromagnet 16 is fixed at the right end of the inner shell 10; the electromagnet and the armature can be attracted or separated, the armature 17 is fixed on the spline housing 18, the spline shaft 11 is connected with the spline housing 18 through a spline, and the spline housing 18 can only move axially relative to the spline shaft 11 and cannot rotate relatively; an annular baffle plate 19 is sleeved on the spline shaft 11 and tightly attached to the first retainer ring 14, and a spring 20 is axially arranged between the baffle plate 19 and the spline housing 18; the rotary encoder 21 consists of a reading head circuit board 21-1 and a code wheel 21-2, the reading head circuit board 21-1 is fixed on the end cover 3, and the code wheel 21-2 is fixed on the output shaft 4. The inner ring of the second bearing 22 is matched with the output shaft 4, and the outer ring is matched with the inner wall of the right shell 2 to limit the radial movement of the output shaft 4 relative to the shell; a second retainer ring 23 is mounted on the output shaft 4 and cooperates with the end cap 3 to axially locate the second bearing 22 and limit axial movement of the output shaft 4 relative to the housing.
In an alternative embodiment, the spring 6 is made of a spring steel material, such as 65 steel in the present embodiment.
In an alternative embodiment, the magnetic shoes of the outer magnetic ring 8 and the inner magnetic ring 9 are made of neodymium iron boron material.
In an alternative embodiment, armature 17 is made of a soft magnetic material having a relatively high magnetic permeability, such as silicon steel in the present embodiment.
In the preferred embodiment, the left housing 1, the right housing 2, the end cover 3, the output shaft 4, the semicircular member 5, the snap ring 7, the inner housing 10, the spline shaft 11, the retainer ring 15 and the spline housing 18 are made of hard aluminum alloy materials.
The working principle and the control method of the vibration isolator are as follows:
according to the principle that the quasi-zero stiffness low-frequency vibration isolation is realized by connecting positive and negative stiffnesses in parallel, under any load torque, as shown in fig. 8(a), after the reed 6 of the positive stiffness element is contacted with the bulge 5-1 to generate bending deformation, the center of the magnetic shoe of the outer magnetic ring 8 and the center of the magnetic shoe of the inner magnetic ring 9 of the negative stiffness element are in a positive state (balance position), and the quasi-zero stiffness state and the vibration isolation effect of the system are optimal.
However, when the load changes, as shown in fig. 8(b), the spring 6 continues to bend and deform, and the inner housing 10 integrated with the spline shaft 11 rotates relative to the outer housing, at this time, the inner magnetic ring 9 and the outer magnetic ring 8 deviate from the equilibrium position, so that the quasi-zero stiffness effect is seriously reduced, and the purpose of low-frequency vibration isolation cannot be achieved. The existing vibration isolation structure rarely considers the problem of balance position deviation caused by load change, so that the vibration isolator only has better vibration isolation performance on fixed load or load in a small change range, and when the load change is larger or the rotation direction is reversed, the vibration isolation performance is seriously reduced or even fails, and the application range of the vibration isolator is influenced.
When the magnetic shoes of the inner magnetic ring 9 and the outer magnetic ring 8 are deviated due to load change, the relative angular displacement of the output shaft 4 relative to the outer shell (namely the deflection angle of the inner magnetic ring 9 relative to the outer magnetic ring 8) is detected through the rotary encoder 21, then the coil 16-2 is controlled to be powered off to release the clutch mechanism, the power device 13 is controlled to drive the inner shell 10 to rotate relative to the spline shaft 11, when the position (balance position) where the magnetic shoes of the inner magnetic ring 9 and the outer magnetic ring 8 are aligned is reached, the coil 16-2 is controlled to be powered on to enable the clutch mechanism to be attracted, at the moment, the reed 6 fixed on the output shaft 4 and the inner magnetic ring 9 fixed on the inner shell 10 are combined into a whole, and the positive rigidity K generated by the reed 6rNegative stiffness K produced by magnetic springmThe mutual offset enables the system to reach a quasi-zero rigidity state, and the vibration isolator effectively isolates low-frequency torsional vibration.
The working principle of the clutch mechanism is as follows: when the coil 16-2 is not energized, the spring 20 presses the spline housing 18 against the right end face of the reed 6, the electromagnet 16 and the armature 17 are separated by a small distance delta, and the clutch mechanism is disengaged, as shown in fig. 6. When the coil 16-2 is electrified, the electromagnet 16 and the armature 17 are mutually attracted by the generated magnetic field, the spline housing 18 overcomes the spring force and moves leftwards along the spline shaft 11, finally the electromagnet 16 and the armature 17 are contacted and synchronously move, the clutch mechanism is attracted, and the inner housing 10 and the spline shaft 11 are integrated into a whole because the spline housing 18 for fixing the armature 17 and the spline shaft 11 cannot relatively rotate.
The balance position adjustment principle of the present invention will be described below by taking an increase in the operating load of the vibration isolator as an example.
When the vibration isolator is in a stable working state, the coil 16-2 is electrified, the inner shell 10 and the spline shaft 11 are combined into a whole, and the load torque at the moment is Krθ0(ii) a When the load of the system changes, the output shaft 4 and the outer shell generate a new relative angular displacement delta theta, and the output shaft 4 generates a relative angular displacement theta relative to the initial state (when not in operation)1(θ1＝θ0+Δθ，θ1＞θ0) (ii) a As shown in fig. 8(b), the magnetic shoes of the inner magnetic ring 9 and the outer magnetic ring 8 also generate a new relative angular displacement Δ θ, and the magnetic spring becomes a deviated state, so that the vibration isolator deviates from the equilibrium position and cannot reach an optimal operating state.
The vibration isolator converts the angular displacement delta theta generated by the output shaft 4 relative to the end cover 3 into corresponding electric pulse signals through the rotary encoder 21 and outputs the electric pulse signals, the electric pulse signals pass through the controller, the control coil 16-2 is powered off, the clutch mechanism is disengaged, and the inner shell 10 is separated from the spline shaft 11; at the moment, the controller sends a pulse signal to the power device 13, so that the motor shaft drives the inner shell 10 to rotate by an angle delta theta in the same direction, and the magnetic shoes of the inner magnetic ring 9 and the outer magnetic ring 8 return to the opposite state again; when the power device 13 stops working, the control coil 16-2 is electrified, the clutch mechanism is closed, the inner shell 10 and the spline shaft 11 are integrated again, and the inner magnetic ring 9 and the outer magnetic ring 8 are kept in a state of being opposite to each other stably.
The positive rigidity generated by the reed 6 is related to the effective acting length (bending length), and because the semi-circular part bulge 5-1 contacted with the reed 6 is horizontally arranged in the axial direction, the effective acting length of the reed 6 is not changed after the load is changed, the positive rigidity of the system is also not changed, and the positive rigidity is still Kr. The negative stiffness generated by the magnetic spring is related to the axial overlapping length (axial length of an air gap) of the outer magnetic ring 8 and the inner magnetic ring 9, and the axial overlapping length of the outer magnetic ring 8 and the inner magnetic ring 9 is not changed in the process of adjusting the position of the inner magnetic ring 9 relative to the outer magnetic ring 8; so that when the magnetic shoes of the outer magnetic ring 8 and the inner magnetic ring 9 are aligned againThe negative stiffness generated by the magnetic spring is also unchanged and still is Km. Positive stiffness K produced by the leaf 6rWith K generated by magnetic springsmAnd mutually offset, and the system reaches a quasi-zero rigidity state again.
The curve of the relationship between the torsional moment and the torsional angle of the reed 6 and the magnetic spring is shown in fig. 9, and it can be seen that the shapes of the corresponding curves of the reed 6 and the magnetic spring are not changed before and after the adjustment, but the corresponding curve of the magnetic spring moves to the right, and the torque transmitted by the system after the adjustment is Krθ1(Krθ1＞Krθ0). The curve of the relation between the total rigidity and the torsion angle of the vibration isolator is shown in figure 10, and it can be seen that the shapes of the curves before and after adjustment are not changed, but the balance position of the system is changed, and the balance position of the system before adjustment is in theta0After adjustment, the equilibrium position is at theta1To (3). Therefore, the vibration isolator can realize quasi-zero rigidity by adjusting the balance position after the system load changes, and effectively isolate low-frequency torsional vibration under different load torques.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A torsion quasi-zero stiffness vibration isolator with an adjustable balance position is characterized by comprising an outer shell, wherein a positive stiffness element and a negative stiffness element are arranged in the outer shell; the positive stiffness element comprises two semicircular pieces and two reeds, wherein the semicircular pieces are arranged oppositely, the reeds are arranged up and down, the semicircular pieces are provided with protrusions along the axial direction, and gaps are formed between the protrusions of the semicircular pieces for the reeds to extend into; the negative stiffness element comprises an outer magnetic ring and an inner magnetic ring, an air gap is arranged between the outer magnetic ring and the inner magnetic ring, the inner magnetic ring is connected with a balance position adjusting mechanism, the balance position adjusting mechanism can drive the inner magnetic ring to rotate so as to adjust the balance position of the inner magnetic ring and the outer magnetic ring, the balance position adjusting mechanism comprises an inner shell, the outer magnetic ring is fixed on the inner wall of an outer shell, the inner magnetic ring is fixed on the outer wall of the inner shell, the inner shell is connected with a power device, the power device drives the inner shell to rotate, the balance position adjusting mechanism is connected with a clutch mechanism, the clutch mechanism comprises an electromagnet fixedly connected with the end part of the inner shell, the electromagnet and an armature can be attracted or separated, the positive stiffness and the negative stiffness can be connected in parallel during attraction, and the balance position can be adjusted after separation.
2. The torsional quasi-zero stiffness vibration isolator of claim 1 wherein one end of the outer housing is connected to the input shaft, an end cap attached to the other end of the outer housing defines a shaft hole for the output shaft to extend through, and the reed is fixedly attached to the output shaft.
3. The torsional quasi-zero stiffness vibration isolator of claim 2 wherein the reed ends are secured between two snap rings, the snap rings being fixedly connected to the output shaft; the matching position of the output shaft and the snap ring is set to be a polygonal structure, and the matching position of the inner wall of the snap ring and the output shaft is set to be a plane.
4. The torsional quasi-zero stiffness vibration isolator of claim 1 wherein the clutch mechanism further comprises a splined shaft, the end of the splined shaft is splined to the splined sleeve, and the armature is splined to the spline
The key sleeve is fixedly connected and can move axially along the spline shaft.
5. The torsional quasi-zero stiffness vibration isolator of claim 4 wherein the splined shaft is connected to the output shaft, a bearing being disposed between the splined shaft and the inner housing; the periphery of the spline shaft is provided with a baffle plate, and a spring is arranged between the baffle plate and the spline housing.
6. The torsional quasi-zero stiffness vibration isolator of claim 5 wherein the output shaft and end cap further fixedly mount a rotary encoder.
7. The torsional quasi-zero stiffness vibration isolator according to claim 1, wherein the outer magnetic ring and the inner magnetic ring each include a plurality of magnetic shoes, the number of the magnetic shoes of the outer magnetic ring and the number of the magnetic shoes of the inner magnetic ring are the same, the magnetic shoes of the outer magnetic ring and the inner magnetic ring are arranged in a one-to-one correspondence, the magnetizing directions of the corresponding magnetic shoes of the outer magnetic ring and the inner magnetic ring are opposite, the magnetizing directions of the magnetic shoes of the inner magnetic ring and the outer magnetic ring are both oriented to a radial direction, and the magnetizing directions of the magnetic shoes of the outer magnetic ring and the inner magnetic ring are alternately changed along the radial direction.
8. The method of operating a torsional quasi-zero stiffness vibration isolator of any of claims 1-7 including the steps of:
when the vibration isolator is not in a working state, the reed is not bent and deformed, and torque is not transmitted;
when the vibration isolator is in a stable working state, the reed is in contact with the semi-circular piece and is bent and deformed, the positive torsional rigidity generated by the reed and the negative rigidity generated by the inner magnetic ring and the outer magnetic ring are mutually offset, and the vibration isolator reaches a quasi-zero rigidity state to realize effective isolation of low-frequency torsional vibration;
when the size or the direction of the load changes, the vibration isolator deviates from a balance position, the inner magnetic ring is driven to rotate through the balance position adjusting mechanism, the inner magnetic ring and the outer magnetic ring reach the next balance position, the vibration isolator reaches a quasi-zero rigidity state again, and low-frequency torsional vibration is still effectively isolated after the load changes.
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