CN112780724B - Rigidity-adjustable quasi-zero rigidity torsion vibration isolator and method - Google Patents
Rigidity-adjustable quasi-zero rigidity torsion vibration isolator and method 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
- F16F15/12—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
- F16F15/121—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 using springs as elastic members, e.g. metallic springs
- F16F15/1215—Leaf springs, e.g. radially extending
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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 quasi-zero stiffness torsion vibration isolator with adjustable stiffness and a method thereof, wherein the quasi-zero stiffness torsion vibration isolator comprises 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 oppositely arranged, the reeds are oppositely arranged, the semicircular pieces are provided with bulges, the bulges are obliquely arranged along the axial direction, and gaps are formed between the bulges of the two 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 and the spring leaf are fixedly connected with the stiffness adjusting mechanism, and the stiffness adjusting mechanism drives the inner magnetic ring and the spring leaf to move axially to adjust the stiffness. The invention can adapt to different working loads and has good low-frequency vibration isolation performance.
Description
Technical Field
The invention belongs to the technical field of torsional vibration isolation, and particularly relates to a quasi-zero stiffness torsional vibration isolator with adjustable stiffness and a method.
Background
The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The rotary machine is widely applied to the industrial fields of aerospace, processing and manufacturing, energy, transportation and the like. As a common dynamic phenomenon in a rotating mechanical system, torsional vibration interferes mechanical equipment, which not only affects machining precision and work efficiency, but also aggravates abrasion to internal precision parts and reduces the service life of the mechanical equipment. Also, the violent vibrations can cause noise problems.
Vibration isolation techniques are often preferred when dealing with the problem of unwanted vibrations. According to the theory of mechanical vibration, the critical vibration isolation frequency of the traditional linear vibration isolation system is the natural frequency of the system
Multiple, i.e. only if the excitation frequency is greater than
The system has vibration isolation effect only when the natural frequency of the system is multiplied. For low-frequency torsional vibration, if a linear vibration isolation method is still adopted, only the natural frequency of a mechanical system can be reduced, but the system rigidity is reduced, the bearing capacity is reduced, and the accuracy and the stability of the system are reduced. Compared with the quasi-zero stiffness vibration isolator, the quasi-zero stiffness vibration isolator has the characteristics of high static stiffness and low dynamic stiffness, has high bearing capacity, and can effectively isolate low-frequency torsional vibration.
At present, the quasi-zero stiffness technology has been applied to isolating torsional vibration, and some researchers have proposed vibration isolators or couplings for eliminating low-frequency torsional vibration of shafting, but such technologies can only effectively isolate low-frequency torsional vibration under design load, and when the load changes, the vibration isolation effect will be obviously reduced. In addition, some scholars propose quasi-zero stiffness torsional vibration isolators with adjustable negative stiffness, the technology can only adjust the negative stiffness but not the positive stiffness, can improve the vibration isolation effect to a certain extent, but still can only play a good vibration isolation role on fixed design load, and once the load changes greatly, the vibration isolators can deviate from the quasi-zero stiffness state greatly to influence 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 when the load is greatly changed, the rigidity cannot be adjusted, or the positive rigidity and the negative rigidity cannot be mutually offset to reach the quasi-zero rigidity state after the rigidity is adjusted, so that the good vibration isolation effect cannot be achieved.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a quasi-zero stiffness torsion vibration isolator with adjustable stiffness 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 invention provides a quasi-zero stiffness torsional vibration isolator with adjustable stiffness, which comprises 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 oppositely arranged, the reeds are oppositely arranged, the semicircular pieces are provided with bulges, the bulges are obliquely arranged on opposite planes of the two semicircular pieces along the axial direction, and gaps are formed between the bulges of the two 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 spring plate and the inner magnetic ring are fixedly connected with the stiffness adjusting mechanism, and the stiffness adjusting mechanism drives the spring plate and the inner magnetic ring to move axially to adjust the stiffness.
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, and the spline shaft extends out of the shaft hole to serve as the output shaft.
As a further technical scheme, the rigidity adjusting mechanism comprises a spline housing, and the spline housing is connected with the spline shaft through a spline; the spline housing is fixedly connected with a power device, and the power device is connected with the spline shaft through a screw rod nut mechanism.
As a further technical scheme, the feed screw nut mechanism comprises a sliding feed screw connected with the power device, the sliding feed screw is connected with a feed screw nut, and the feed screw nut is fixedly connected with the spline shaft.
As a further technical scheme, the power device is provided with a magnetic encoder, the spline shaft and the end cover are provided with a rotary encoder, the magnetic encoder and the rotary encoder are both connected with the controller, and the controller controls the power device to act.
As a further technical scheme, the spline housing is arranged in the outer shell, the reed is fixed on the periphery of the spline housing through two semicircular snap rings, and the snap rings are fixedly connected with the spline housing; the inner magnetic ring is fixed on the periphery of the magnetic shoe fixing ring, and the magnetic shoe fixing ring is fixedly connected with the spline housing.
As a further technical scheme, the inner wall of the clamping ring and the outer wall of the spline housing are both provided with a plurality of planes.
As a further technical scheme, a bearing is arranged between the spline shaft and the outer shell, a check ring is arranged on the periphery of the spline shaft and is tightly attached to an inner ring of the bearing.
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 and the number of the magnetic tiles of the inner magnetic ring are the same, 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 magnetic tiles of the outer magnetic ring and the magnetic tiles of the inner magnetic ring are staggered by a set angle in an initial state, the magnetizing directions of the corresponding magnetic tiles of the outer magnetic ring and the corresponding magnetic tiles of 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 alternate 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 does not bend and deform and does not transmit torque, and at the moment, the magnetic shoes of the outer magnetic ring and the inner magnetic ring are staggered by a certain angle theta in the circumferential direction0；
When the vibration isolator is in a 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. But the quasi-zero state corresponds to a fixed load torque Kr1θ0When the load of the system changes, the vibration isolator deviates from the optimal working position, and the vibration isolation effect is obviously reduced or even fails.
The vibration isolator can convert the angular displacement generated by the spline shaft relative to the shell into corresponding electric pulse signals through the rotary encoder and output the electric pulse signals, and the load torque of the vibration isolator can be obtained through the controller. The magnetic encoder can detect the rotating angle of the output shaft of the power device and control the operation of the power device, so that the power device can be controlled to rotate by a proper angle, the spline sleeve moves a proper distance relative to the spline shaft in the axial direction, and the contact position of the reed and the semicircular piece is changed, so that the effective acting length of the reed is changed, and the positive rigidity is adjusted; and simultaneously, the length of an air gap between the outer magnetic ring and the inner magnetic ring in the axial direction is changed, so that the magnitude of the negative stiffness is synchronously adjusted. When the new stable working state is reached, the positive stiffness and the negative stiffness are still approximately offset, so that the total stiffness of the vibration isolator is still close to zero. Different from the vibration isolator before adjustment, the positive stiffness generated by the reeds is changed, and the load torque transmitted by the reeds is different from that before adjustment, so that the vibration isolator can adapt to different load states, and can still effectively isolate low-frequency torsional vibration after the system load is changed.
In a second aspect, the embodiment of the present invention further provides an operating method of the quasi-zero stiffness torsional 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 load changes, the inner magnetic ring and the reed are driven to move axially through the rigidity adjusting mechanism, the contact position of the reed and the bulge and the axial length of an air gap between the inner magnetic ring and the outer magnetic ring are changed, so that the negative rigidity and the positive rigidity correspondingly change, the positive rigidity and the negative rigidity are offset with each other again, the vibration isolator reaches a quasi-zero rigidity state again, and low-frequency torsional vibration is effectively isolated after the load changes.
The beneficial effects of the above-mentioned embodiment of the present invention are as follows:
the quasi-zero stiffness torsional vibration isolator with adjustable stiffness utilizes the reed as a positive stiffness element and is connected with the permanent magnet negative stiffness element in parallel, has high static stiffness, can effectively transmit torque, has low dynamic stiffness, can effectively isolate low-frequency torsional vibration, and widens the vibration isolation frequency band.
The quasi-zero stiffness torsion vibration isolator with adjustable stiffness can drive positive and negative stiffness elements to synchronously move through the stiffness adjusting mechanism according to the change of working load so as to automatically and synchronously adjust the positive and negative stiffness, so that the vibration isolator can reach a quasi-zero stiffness working state under different loads, and the vibration isolation range and the vibration isolation performance of the vibration isolator are effectively improved.
The stiffness-adjustable quasi-zero stiffness torsional vibration isolator adopts one power device to adjust positive stiffness and negative stiffness simultaneously, and has the advantages of compact structure and simple control.
According to the quasi-zero stiffness torsion vibration isolator with the adjustable stiffness, the screw and nut mechanism in the stiffness adjusting mechanism has a self-locking function, namely when the working load is stable and adjustment is not needed, the quasi-zero stiffness torsion vibration isolator can keep the current working state without additionally providing energy, so that the energy consumption can be reduced.
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.
FIG. 1 is a schematic view of the vibration isolator of the present invention;
FIG. 2 is a view taken along line A-A of FIG. 1;
FIG. 3 is a schematic view of a spline housing structure and a reed installation;
FIG. 4(a) is a view from B-B in FIG. 1, showing the vibration isolator in a non-operational state;
FIG. 4(B) is a view from B-B in FIG. 1, showing the vibration isolator in an operating condition;
FIG. 5 is an enlarged view of a portion of FIG. 1 at C;
FIG. 6 is a schematic view showing the installation of part of the spline shaft;
FIG. 7 is a schematic view of the synchronous adjustment of positive and negative stiffness of the vibration isolator of the present invention;
FIG. 8 is a graph of torsional stiffness versus torsional angle for magnetic springs of different tuning lengths;
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;
the device comprises a left shell 1, a right shell 2, a spline shaft 3, a spline housing 4, an end cover 5, a semicircular piece 6, a bulge 6-1, a reed 7, a snap ring 8, an outer magnetic ring 9, an inner magnetic ring 10, a magnetic shoe fixing ring 11, a stepping motor 12, a sliding lead screw 12-1, a lead screw nut 13, a magnetic encoder 14, a rotary encoder 15, a reading head circuit board 15-1, a coded disc 15-2, a bearing 16 and a retainer ring 17.
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 up, down, left and right directions 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 referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus 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 described in the background of the invention, the prior art has shortcomings, and in order to solve the above technical problems, the invention provides a stiffness-adjustable quasi-zero stiffness torsional vibration isolator and a method thereof.
In an exemplary embodiment of the invention, as shown in fig. 1, a quasi-zero stiffness torsional vibration isolator with adjustable stiffness is provided, which comprises a left shell 1, a right shell 2, and a positive stiffness element, a negative stiffness element and a stiffness adjusting mechanism inside the shells.
Wherein, the left shell and the right shell are connected to form an outer shell; the left shell 1 and the right shell 2 are fixedly connected through bolts and nuts. And one side of the left shell 1 is provided with a shaft hole and a key groove which are connected with an input shaft. A spline shaft 3 and a spline housing 4 are arranged in the right shell, the spline housing is sleeved outside the spline shaft, the spline shaft and the spline housing are connected through a spline and synchronously rotate, the spline housing 4 can axially move relative to the spline shaft 3, and the spline housing and the outer shell are coaxially arranged; one side of the spline shaft 3 is provided with a key groove and extends out of the shell through a shaft hole of the end cover 5 to be used as an output shaft; the end cover 5 is fixedly connected with the right shell 2 through screws.
A positive stiffness element is disposed within the left housing. The positive stiffness element comprises a semi-circular piece 6 and a leaf 7 as shown in figure 2. The number of the semicircular pieces is two, the two semicircular pieces are fixedly connected to the inner part of the left shell through screws, and a semicircular column bulge 6-1 with a certain inclination is arranged on each semicircular piece 6; a narrow gap is formed between the bulges 6-1 of the two semicircular pieces 6 for the reeds 7 to extend into.
When the device works, the reed is contacted with the semi-cylindrical bulge on the semi-circular piece, and the generated torsional rigidity is positive and is used for transmitting driving torque.
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.
The bulge 6-1 is obliquely arranged along the axial direction of the semicircular piece, namely, the distance between the bulge and the center of the semicircular piece is gradually reduced from one end to the other end in the axial direction; in this embodiment, the distance between the protrusion and the center of the semicircular member is gradually reduced from the left end to the right end in the axial direction.
As shown in fig. 3, the upper and lower reeds 7 are installed between the left and right semicircular snap rings 8, and the two snap rings 8 are fixed on the spline housing 4 through bolts and nuts; the fit position of the snap ring and the spline housing is set to be a plurality of planes, and the inner wall of the snap ring 8 and the outer wall of the spline housing 4 are provided with partial planes, and connection is formed through the plane fit of the snap ring and the spline housing, so that no relative motion exists between the reed 7 and the spline housing 4. In this embodiment, through arc face, plane combination complex mode between spline housing outer wall and the snap ring inner wall, can be firm realize the two fixed connection and can not produce relative motion.
A negative stiffness element is disposed within the right housing. The negative stiffness element comprises an outer magnetic ring 9 and an inner magnetic ring 10, a certain air gap is arranged between the outer magnetic ring 9 and the inner magnetic ring 10, and the outer magnetic ring 9 and the inner magnetic ring 10 form a magnetic spring; the outer magnetic ring 9 is fixed on the inner wall of the right shell 2, the inner magnetic ring 10 is fixed on the magnetic shoe fixing ring 11, and the magnetic shoe fixing ring 11 is fixedly connected with the spline housing 4.
The torsional rigidity generated by the inner magnetic ring and the outer magnetic ring is negative.
In a further scheme, the outer magnetic ring 9 and the inner magnetic ring 10 are formed by combining a plurality of magnetic tiles, the number of the magnetic tiles of the outer magnetic ring 9 and the number of the magnetic tiles of the inner magnetic ring 10 are the same, 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 alternative, the angular width of the magnetic shoes of the outer magnetic ring 9 in the circumferential direction is slightly larger than the magnetic shoes of the inner magnetic ring 10, as shown in fig. 4 (b).
The rigidity adjusting mechanism is composed of a spline shaft 3, a spline housing 4, a stepping motor 12, a feed screw nut 13, a magnetic encoder 14 and a rotary encoder 15, wherein the stepping motor 12 (namely a power device) is fixed on the spline housing 4, and the feed screw nut 13 is fixed on the spline shaft 3; the output shaft of the stepping motor 12 is a sliding screw rod 12-1, the sliding screw rod 12-1 and a screw rod nut 13 form a screw rod nut mechanism, and the sliding screw rod 12-1 can be self-locked without active input; when the stepping motor 12 rotates, the sliding screw 12-1 and the screw nut 13 move relatively, so that the spline housing 4 moves axially relative to the spline shaft 3.
In this embodiment, the sliding screw 12-1 is disposed in the spline housing, and the screw nut is fixedly connected with the spline shaft in the spline housing.
The magnetic encoder 14 is fixed at the tail of the stepping motor 12; as shown in FIG. 5, the rotary encoder 15 is composed of a reading head circuit board 15-1 and a code wheel 15-2, the reading head circuit board 15-1 is fixed on the end cover 5, and the code wheel 15-2 is fixed on the spline shaft 3. The magnetic encoder and the rotary encoder are both connected with the controller, and the controller controls the stepping motor to act.
The inner ring of the bearing 16 is matched with the spline shaft 3, and the outer ring is matched with the right shell 2 and used for limiting the radial movement of the spline shaft 3 relative to the shell; as shown in fig. 6, a retainer ring 17 is mounted on the spline shaft 3 and abuts against the right side of the bearing inner race for limiting the axial movement of the spline shaft 3 relative to the housing; the bearing 16 and the retainer ring 17 cooperate to allow only a slight amount of rotation of the spline shaft 3 relative to the housing.
In an alternative embodiment, the spring 7 is made of a spring steel material, such as 65 steel in the present embodiment.
In a preferred embodiment, the magnetic shoes of the outer magnetic ring 9 and the inner magnetic ring 10 are made of neodymium iron boron material.
In a preferred embodiment, the left shell 1, the right shell 2, the spline shaft 3, the spline housing 4, the end cover 5, the semicircular piece 6, the snap ring 8 and the magnetic shoe fixing ring 11 are made of hard aluminum alloy materials.
The working principle and the control method of the invention are as follows:
when the vibration isolator is not in a working state, the reeds 7 are not in contact with the semicircular piece 6, so that the reeds 7 do not bend and deform and do not generate torque; the magnetic shoes of the outer magnetic ring 9 and the inner magnetic ring 10 are staggered by a certain angle theta0As shown in fig. 4 (a).
When the vibration isolator is in the optimal working state, the input shaft drives the shell to rotate relative to the spline sleeve 4 to generate a relative angular displacement theta0(allowed at θ)0Small-range fluctuation nearby), the reed 7 is contacted with the bulge 6-1 of the semicircular part to generate bending deformation, and the torsional positive rigidity K is generatedr1Providing a drive torque of Kr1θ0(ii) a At this time, the magnetic shoes of the outer magnetic ring 9 and the inner magnetic ring 10 are just opposite to each other, as shown in fig. 4(b), and the magnetic torque generated by the two is zero, but a large negative stiffness K can be generatedm1. Negative stiffness K produced by magnetic springm1Positive stiffness K with spring 7r1And the total rigidity of the system is just offset, so that the total rigidity of the system reaches a quasi-zero state, and the low-frequency torsional vibration is effectively isolated. And the working load of the vibration isolator is only the torque K provided by the reed 7 at the momentr1θ0Therefore, the vibration isolator can be ensured to have higher bearing capacity.
However, the quasi-zero state described above corresponds only to a fixed load torque Kr1θ0When the load of the system changes, the vibration isolator can deviate from the optimal working position, so that the vibration isolation effect is obviously reduced and even fails.
The stiffness adjustment principle of the present invention will be described below with reference to fig. 7 and 8, taking the reduction of the operational load of the vibration isolator as an example.
When the workload decreases, the isolator may not work optimallyIn the state, the angular displacement generated by the spline shaft 3 relative to the end cover 5 (namely the outer shell) can be converted into a corresponding electric pulse signal by the rotary encoder 15, and the electric pulse signal is output, so that the load torque of the vibration isolator after being changed is obtained through the controller; the magnetic encoder 14 detects the rotating angle of the sliding screw rod 12-1 of the stepping motor, controls the running of the stepping motor 12 and further controls the rotating angle of the sliding screw rod 12-1. When the magnetic encoder 14 detects that the rotation angle of the sliding screw rod 12-1 is alpha, the stepping motor stops working, and the spline sleeve 4 moves leftwards relative to the spline shaft 3 by a distance L; at this time, the contact position of the spring 7 with the projection 6-1 of the semicircular member and the air gap between the outer magnetic ring 9 and the inner magnetic ring 10 are changed in length in the axial direction as shown in fig. 7. The positive stiffness generated by the reed 7 is related to the effective acting length (bending length), and the greater the effective acting length is, the lower the stiffness is; because the semicircular bulge 6-1 in contact with the spring 7 is obliquely arranged in the axial direction, when the spring 7 moves leftwards relative to the semicircular bulge 6-1, the effective acting length of the spring 7 is increased, and the positive rigidity of the vibration isolator is reduced. Adjusting the positive stiffness of the front spring to Kr1Providing a torque of Kr1θ0And after the reed 7 moves leftwards, the positive rigidity is Kr2(Kr2＜Kr1) Providing a torque of Kr2θ0(ii) a The negative stiffness generated by the magnetic spring is related to the length of the air gap between the outer magnetic ring 9 and the inner magnetic ring 10 along the axial direction, as shown in fig. 8, which is a torsion stiffness-torsion angle relation curve of the magnetic spring under different adjustment lengths L, it can be seen that the larger the axial adjustment length L is, the smaller the negative stiffness generated by the magnetic spring at the equilibrium position is. When the inner magnetic ring 10 moves to the left by a distance L relative to the outer magnetic ring 9, the stiffness of the magnetic spring is changed from the original Km1Decrease to Km2The adjusted positive stiffness K can be realized through reasonable parameter designr2And negative stiffness Km2Approximately offset, the total stiffness of the system is still close to zero, so the vibration isolator can adapt to different load torques by adjusting the positive stiffness and the negative stiffness, and can still effectively isolate low-frequency torsional vibration after the load of the system is changed.
The vibration isolator has the characteristics of high static rigidity-low dynamic rigidity near the working position, can effectively transmit driving torque, and can effectively isolate low-frequency torsional vibration. Meanwhile, the positive stiffness and the negative stiffness of the vibration isolator can be synchronously adjusted through one motor, so that the vibration isolator can adapt to different loads, quasi-zero stiffness can be realized under different loads, and the working range of the vibration isolator is effectively enlarged.
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 quasi-zero stiffness torsional vibration isolator with adjustable stiffness 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 oppositely arranged, the reeds are oppositely arranged, the semicircular pieces are provided with bulges, the bulges are obliquely arranged along the axial direction, and gaps are formed between the bulges of the two 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 and the reed are fixedly connected with the stiffness adjusting mechanism, the stiffness adjusting mechanism drives the inner magnetic ring and the reed to move axially, the contact position of the reed and the bulge and the axial length of the air gap between the inner magnetic ring and the outer magnetic ring are changed, so that the negative stiffness and the positive stiffness are correspondingly changed, the positive stiffness and the negative stiffness are mutually offset again, and the vibration isolator reaches a quasi-zero stiffness state again to adjust the stiffness;
the outer shell comprises a left shell and a right shell; the reed is arranged between the left semicircular clamping ring and the right semicircular clamping ring; the bulges are arranged at the opposite positions of the two semicircular parts; the outer magnetic ring is fixed on the inner wall of the right shell;
the rigidity adjusting mechanism comprises a spline sleeve, and the spline sleeve is connected with the spline shaft through a spline; the spline housing is fixedly connected with a power device, and the power device is connected with the spline shaft through a screw rod nut mechanism;
the spline housing is arranged in the outer shell, the end parts of the reeds are fixed between the two snap rings, and the snap rings are fixedly connected with the spline housing; the inner magnetic ring is fixed on the periphery of the magnetic shoe fixing ring, and the magnetic shoe fixing ring is fixedly connected with the spline housing.
2. The quasi-zero stiffness torsional vibration isolator of claim 1 in which one end of the outer housing is connected to the input shaft and the end cap connected to the other end of the outer housing is provided with a shaft hole from which the splined shaft extends as the output shaft.
3. The quasi-zero stiffness torsional vibration isolator of claim 1 wherein the lead screw and nut mechanism includes a sliding lead screw coupled to a power plant, the sliding lead screw coupled to a lead screw nut, the lead screw nut fixedly coupled to the splined shaft.
4. The quasi-zero stiffness torsional vibration isolator of claim 1 wherein the power plant is provided with a magnetic encoder, the spline shaft and the end cap are provided with a rotary encoder, both the magnetic encoder and the rotary encoder are connected to a controller, and the controller controls the power plant to operate.
5. The quasi-zero stiffness torsional vibration isolator of claim 1 wherein the inner snap ring wall and the outer spline housing wall each define a plurality of flats.
6. The quasi-zero stiffness torsional vibration isolator of claim 2, wherein a bearing is disposed between the splined shaft and the outer housing, and a retaining ring is disposed around the splined shaft and abuts against an inner race of the bearing.
7. The quasi-zero stiffness torsional 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 one-to-one correspondence, and the magnetic shoes of the outer magnetic ring and the inner magnetic ring are staggered by a set angle in an initial state, 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 in the radial direction.
8. The method of operating a quasi-zero stiffness torsional vibration isolator of any of claims 1 to 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;
when the load changes, the inner magnetic ring and the reed are driven to move axially through the rigidity adjusting mechanism, the contact position of the reed and the bulge and the axial length of the air gap between the inner magnetic ring and the outer magnetic ring are changed, so that the negative rigidity and the positive rigidity correspondingly change, the positive rigidity and the negative rigidity are offset with each other again, and the vibration isolator reaches a quasi-zero rigidity state again.
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| CN202011636754.8A CN112780724B (en) | 2020-12-31 | 2020-12-31 | Rigidity-adjustable quasi-zero rigidity torsion vibration isolator and method |
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| CN202011636754.8A CN112780724B (en) | 2020-12-31 | 2020-12-31 | Rigidity-adjustable quasi-zero rigidity torsion vibration isolator and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US9593739B2 (en) * | 2013-12-06 | 2017-03-14 | Hrl Laboratories, Llc | Negative stiffness hydraulic system |
| CN105526270A (en) * | 2016-01-18 | 2016-04-27 | 西安交通大学 | Quasi-zero stiffness coupling |
| CN106402262B (en) * | 2016-11-11 | 2017-10-27 | 中国人民解放军海军工程大学 | A kind of adjustable magnetic quasi-zero stiffness vibration isolators of rigidity |
| CN108708927B (en) * | 2018-05-24 | 2019-04-30 | 上海大学 | A kind of Variable Stiffness Vibration Isolator based on multilayer dielectric elastomer film |
| CN108662055B (en) * | 2018-07-30 | 2019-09-27 | 上海大学 | A kind of quasi-zero stiffness vibration isolators of positive and negative Stiffness |
| CN109027124B (en) * | 2018-09-12 | 2020-02-11 | 西安交通大学 | Torsion quasi-zero stiffness vibration isolator with adjustable negative stiffness and control method |
| CN109139789A (en) * | 2018-10-22 | 2019-01-04 | 深圳鑫安满金融服务有限公司 | The adjustable quasi- zero stiffness vibration-isolating platform of positive negative stiffness |
| CN110513419B (en) * | 2019-09-23 | 2020-07-14 | 上海大学 | Adjustable quasi-zero stiffness vibration isolator based on magnetic circuit design |
| CN111734780B (en) * | 2020-06-29 | 2022-03-29 | 哈尔滨工业大学 | Ultralow frequency air spring vibration isolator based on axial magnetization magnetic ring negative stiffness structure |
| CN111927912B (en) * | 2020-07-15 | 2021-10-12 | 江苏大学 | Quasi-zero rigidity vertical vibration isolator capable of realizing balance position adjustment |
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