A rotor dynamic vibration absorber that suppresses axial vibrations

Abstract

The present application relates to a kind of rotor dynamic vibration absorber of inhibiting axial vibration, including vibration absorber body, fixed frame, guide component, vibration absorber body is connected with fixed frame by guide component, guide component is arranged in parallel with transmission shaft to be inhibited vibration, vibration absorber body moves along guide component and realizes inhibiting axial vibration;The fixed frame includes two symmetrical support plates arranged on left and right, and transmission shaft is installed on support plate by double-row tapered roller bearing;Vibration absorber body includes mass unit, linear bearing and spring unit, magnetic damping unit being arranged between mass unit and support plate.The present application has better inhibiting performance to the vibration and impact vibration in the frequency band range of ±15%~±20% of rotor system resonance frequency.

Description

Technical Field

[0001] This invention belongs to the field of vibration absorption technology, and particularly relates to a rotor-driven vibration absorber for suppressing axial vibration, used for suppressing axial vibration in ship shafting systems. Background Technology

[0002] During ship navigation, propeller blades create a non-uniform wake field at the stern. The pulsating force generated by the propeller's operation within this wake causes axial vibration in the propeller shafting at the propeller blade frequency or double the blade frequency. This axial vibration is transmitted through the propeller shafting, thrust bearing, and its base to the hull, causing hull vibration and ultimately underwater noise radiation. Therefore, the axial vibration of the ship's propeller shafting caused by propeller excitation directly affects the ship's quietness and comfort. Among a series of measures to reduce shafting axial vibration, installing a dynamic vibration absorber is an effective and feasible method.

[0003] Li Liangwei et al. theoretically derived the method for a passive Vogit-type dynamic vibration absorber to suppress vibrations of ship shafting systems subjected to harmonic forces. Their results showed that, theoretically, this type of absorber can effectively suppress the resonance peak during longitudinal resonance of the shafting. However, because the stiffness of the elastic element in this type of dynamic vibration absorber is constant, its ability to transfer shafting energy is limited. Yang Zhirong et al. designed a tunable semi-active vibration absorber using the controllable shear stiffness of magnetorheological elastomers. Tests showed that this absorber has a certain suppressive effect on axial vibrations of ship shafting systems. However, the structural properties of magnetorheological elastomers are unstable, and the stiffness variation range of the elastomer is limited, preventing large-scale frequency shifting of the rotor shafting. Furthermore, a control system is required, making the structure relatively complex. In addition, existing axial dynamic vibration absorbers do not show significant vibration suppression effects under impact loads. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a rotor dynamic vibration absorber that suppresses axial vibration. It suppresses axial vibration and impact vibration in the frequency band of ±15% to ±20% of the resonance frequency, has a relatively efficient axial vibration energy absorption capacity, and has good suppression performance for a wide frequency band of vibration and impact vibration of the rotor system.

[0005] A rotor-powered vibration absorber for suppressing axial vibration includes a vibration absorber body, a fixed frame, and a guide assembly. The vibration absorber body is connected to the fixed frame through the guide assembly. The guide assembly is arranged parallel to the drive shaft whose vibration is to be suppressed. The vibration absorber body moves along the guide assembly to achieve axial vibration along the drive shaft, thereby suppressing the axial vibration of the drive shaft.

[0006] The fixed frame is the load-bearing element of the vibration absorber body, including two symmetrically arranged support plates on the left and right. The support plates are support plates with perforated shoulders, and double-row tapered roller bearings are installed in the holes. The drive shaft is mounted on the support plates through the double-row tapered roller bearings.

[0007] The vibration absorber body includes a mass unit, a linear bearing, and a spring unit and a magnetic damping unit disposed between the mass unit and the support plate. The mass unit is a ring with multiple mounting holes evenly distributed around its circumference. The mounting holes are used to install the linear bearing, and the guide assembly is installed on the inner ring of the linear bearing.

[0008] The spring unit is a vibration absorber comprising an even number of springs, with every two springs symmetrically installed on both sides of the linear bearing between the mass unit and the support plate; the other end of the spring connected to the support plate is embedded in a spring fixing sleeve with a threaded hole, and the side with the smaller pitch is closer to the spring fixing sleeve; the side of the spring connected to the mass unit is fixed by a spring washer.

[0009] The spring is an unequal pitch helical cylindrical spring.

[0010] The spring washer is a helical spring washer, which is fixed to the mass unit by a first external hexagonal bolt.

[0011] The spring washer is provided with a first cylindrical locating pin, which is used to cooperate with the first external hexagonal bolt to fix the spring washer.

[0012] The magnetic damping unit includes eight sets of stepped magnetic damping devices, symmetrically installed between the mass unit and the support plate, and evenly distributed along the circumference of the mass unit; each stepped magnetic damping device includes a magnet, which is cuboid in shape, and each set of stepped magnetic damping devices includes a pair of magnets, which are mounted on the support plate by a magnet fixing plate and evenly installed along the circumference of the first and second support plates; magnetic line cutting discs are provided on the mass unit at the position corresponding to the magnet pair by a cutting disc connecting plate.

[0013] The magnetic wire cutting sheet is a magnetic wire cutting sheet with unequal cross-section. The end near the magnet pair has a stepped thickness, and the cross-section is smaller and the thickness is thinner as it gets closer to the magnet pair.

[0014] The guide assembly includes double-ended threaded studs corresponding to the number of mounting holes of the mass unit. The double-ended threaded studs are evenly distributed on the support plate, installed on the inner ring of the linear bearing, and arranged parallel to the drive shaft. The double-ended threaded studs pass through the first support plate, the spring between the first support plate and the mass unit, the mass unit, the spring between the first support plate and the mass unit, and the second support plate in sequence. The threaded ends are fixed to the support plate by hexagonal nuts and spring retaining sleeves with threaded holes.

[0015] The beneficial effects of this invention are:

[0016] 1. Four double-ended threaded studs are used in conjunction with linear bearings to support and guide the vibration absorber mass unit, which prevents the circumferential rotation of the vibration absorber mass unit and ensures the correct direction of motion when the vibration absorber mass unit generates axial vibration.

[0017] 2. This invention employs eight unequal-pitch helical cylindrical springs, divided into four groups. Each group has two springs symmetrically installed, and the four groups of springs are evenly distributed circumferentially on both sides of the vibration absorber mass unit, ensuring system equilibrium. Regardless of whether the vibration absorber mass unit vibrates to the left or right, the four springs on one side of the mass unit can be compressed. Due to the unequal-pitch structure of the springs, their stiffness increases non-linearly with the amount of compression. The amplitude changes due to different vibration frequencies, thus the variable stiffness characteristic of the springs allows the vibration absorber to have a vibration-absorbing effect within a frequency band of ±15% to ±20% of the resonant frequency.

[0018] 3. In this invention, eight sets of magnetic field line cutting discs with unequal cross-sections are used in conjunction with magnets to form a magnetic damping unit. When the rotor amplitude is small, the narrow cross-section of the magnetic field line cutting discs cuts the magnetic field lines, generating small damping; when the amplitude is large, the wide cross-section of the cutting discs participates in cutting the magnetic field lines, generating large damping. This damping variation characteristic related to rotor amplitude enables the rotor to have a certain vibration resistance effect when subjected to partial impact, thereby dissipating the energy of slight vibrations or strong impact vibrations, and thus achieving the purpose of suppressing impact vibrations. Attached Figure Description

[0019] Figure 1 This is a front view of the vibration absorber provided by the present invention;

[0020] Figure 2 for Figure 1 Sectional view along axis AA;

[0021] Figure 3 This is a schematic diagram of the support plate in this invention;

[0022] Figure 4 This is a front view of the spring retaining sleeve in this invention;

[0023] Figure 5 This is a right view of the spring retaining sleeve in this invention;

[0024] Figure 6 This is a schematic diagram of the stiffness curve of the spring in this invention;

[0025] in,

[0026] 1-Hexagonal nut, 2-First support plate, 3-Spring retaining sleeve, 4-Spring, 5-Spring washer, 6-First external hexagonal bolt, 7-Mass unit, 8-Linear bearing, 9-Cut disc connecting plate, 10-Second external hexagonal bolt, 11-Magnetic wire cutting disc, 12-Magnet pair, 13-Magnet fixing plate, 14-Third external hexagonal bolt, 15-Double-ended threaded stud, 16-Second support plate, 17-First cylindrical locating pin, 18-Second cylindrical locating pin. Detailed Implementation

[0027] To better explain and facilitate understanding of the present invention, the technical solution and effects of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1-2 As shown, a rotor power vibration absorber for suppressing axial vibration includes a vibration absorber body, a fixed frame, and a guide assembly. The vibration absorber body is connected to the fixed frame through the guide assembly. The guide assembly serves as a guide device and is arranged parallel to the transmission shaft whose vibration is to be suppressed. The vibration absorber body moves along the guide assembly to achieve axial vibration along the transmission shaft, thereby suppressing the axial vibration of the transmission shaft.

[0029] The fixing frame is the load-bearing element of the vibration absorber body, including two symmetrically arranged support plates, namely the first support plate 2 and the second support plate 16. The two have the same structure and can be used interchangeably; the first support plate 2 is as follows: Figure 3 As shown. The support plate is a support plate with a perforated shoulder, and a double-row tapered roller bearing is installed in the hole. The drive shaft is mounted on the support plate through the double-row tapered roller bearing. The axial vibration of the drive shaft can be transmitted to the fixed frame through the bearing, and then transmitted to the vibration absorber body by the fixed frame.

[0030] The vibration absorber consists of a mass unit 7, a linear bearing 8, and a spring unit and a magnetic damping unit disposed between the mass unit 7 and the support plate. The mass unit 7 is a ring with four evenly distributed mounting holes on its circumference. The four mounting holes on the ring are used to install the linear bearing 8, and a guide assembly is installed on the inner ring of the linear bearing 8. The linear bearing 8 is installed in the four evenly distributed mounting holes of the mass unit 7, enabling the vibration absorber mass unit 7 to achieve linear translation and smooth sliding during axial vibration. The spring unit includes eight springs 4, which are unequal pitch helical cylindrical springs. Every two springs 4 are symmetrically installed on both sides of the linear bearing 8 between the mass unit 7 and the support plate, with the side with the smaller pitch closer to the spring fixing sleeve 3. The other end of the spring 4 connected to the support plate is embedded in the spring fixing sleeve 3 with a threaded hole. The spring fixing sleeve 3 is as follows: Figure 4-5 As shown; the side of spring 4 connected to mass unit 7 is fixed by spring washer 5; the stiffness curve diagram of the unequal pitch helical cylindrical spring in this embodiment is shown in the figure. Figure 6As shown, the greater the compression of spring 4, the greater its stiffness. The spring washer 5 is a helical spring washer, which is fixed to the mass unit 7 by a first external hexagonal bolt 6. A first cylindrical locating pin 17 is provided on the spring washer 5, used to cooperate with the first external hexagonal bolt 6 to fix the spring washer 5. When the vibration frequency is different, the amplitude of the drive shaft and the vibration absorber are different. The unequal pitch helical cylindrical spring has different compression amounts according to the different amplitudes, and can achieve energy storage function within the frequency band of ±15% to ±20% of the resonant frequency. The magnetic damping unit includes eight sets of stepped magnetic damping devices, symmetrically installed between the mass unit 7 and the support plate, and evenly distributed along the circumference of the mass unit 7. Each stepped magnetic damping device includes a magnet, which is cuboid in shape. Each set of stepped magnetic damping devices includes a pair of magnets 12, which are mounted on the support plate via a magnet fixing plate 13, and are evenly installed along the circumference of the first support plate 2 and the second support plate 16. The magnet fixing plate 13 is connected to the support plate via a third external hexagonal bolt 14. Magnetic field line cutting discs 11 are provided on the mass unit 7 at the position corresponding to the magnet pair 12 via a cutting disc connecting plate 9. Similarly, the cutting disc connecting plate 9 is evenly installed on both sides of the mass unit 7 of the vibration absorber body via a second external hexagonal bolt 10. A second cylindrical positioning pin 18 is provided on the cutting disc connecting plate 9, which cooperates with the second external hexagonal bolt 10 to fix the cutting disc connecting plate 9. The magnetic field line cutting disc 11 is a magnetic field line cutting disc with an unequal cross-section. The end near the magnet pair 12 has a stepped thickness, and the cross-section becomes smaller and the thickness becomes thinner as it gets closer to the magnet pair 12. When the amplitude is different, the magnetic field line cutting disc 11 with different thicknesses cuts the magnetic field lines to generate damping. The larger the amplitude, the thicker the cutting disc participating in the cutting of the magnetic field lines, the longer the participating part, and the greater the damping generated, thereby achieving the purpose of consuming the energy of slight vibration or strong impact vibration.

[0031] The guiding assembly includes four double-ended threaded studs 15 corresponding to the number of mounting holes in the mass unit 7. These four studs 15 are evenly distributed on the support plate and mounted on the inner ring of the linear bearing 8, arranged parallel to the drive shaft. The double-ended threaded studs 15 sequentially pass through the first support plate 2, the spring 4 between the first support plate 2 and the mass unit 7, the mass unit 7, the spring 4 between the first support plate 2 and the mass unit 7, and the second support plate 16. The threaded ends are fixed to the support plate by hexagonal nuts 1 and spring retaining sleeves 3 with threaded holes. The unthreaded portion of the double-ended threaded studs 15 has a surface roughness of Ra0.8. The mass unit 7 of the vibration absorber body can slide left and right along the unthreaded portion of the double-ended threaded studs 15 via the linear bearing 8. The unthreaded portion serves as a guide rail for the movement of the mass unit 7, allowing it to move linearly left and right.

[0032] The assembly steps of the rotor dynamic vibration absorber for suppressing axial vibration described above are as follows:

[0033] Using eight sets of second hexagonal bolts 10 and second cylindrical locating pins 18, the cutting plate connecting plate 9 holding the magnetic wire cutting plate 11 is installed on the mass unit 7; four linear bearings 8 are respectively installed in the four mounting holes of the mass unit 7; spring washers 5 are installed on the mass unit 7 using first hexagonal bolts 6, for a total of eight sets; the two polar magnets of the magnet pair 12 are respectively pasted on the two magnet fixing plates 13, for a total of eight sets; then, using third hexagonal bolts 14 and second cylindrical locating pins 18, the magnet fixing plate 13 with the pasted magnet pair 12 is installed on the first support plate 2 and the second support plate 16. First support plate 2, mass unit 7, and second support plate 16 are sequentially fitted onto the transmission shaft section requiring vibration damping. The shoulder holes of first support plate 2 and second support plate 16 are respectively fitted with pre-installed double-row tapered roller bearings. Double-threaded studs 15 are passed through the through hole from the side of second support plate 16, and then sequentially through the inner ring of linear bearing 8 and the through hole of first support plate 2. During this process, two spring retaining sleeves 3 and springs 4 are sequentially fitted onto double-threaded studs 15. Note that the two springs 4 are installed facing each other, with the side with the smaller pitch closer to the spring retaining sleeve 3. The two hexagonal nuts 1 are then installed. At the threads at both ends of the double-ended threaded stud 15; install the remaining three sets of double-ended threaded studs 15, spring retaining sleeves 3, springs 4, and hexagonal nuts 1 on the remaining three holes of the first support plate 2 and the second support plate 16; tighten the two hexagonal nuts 1, and at the same time rotate the two spring retaining sleeves 3 so that the spring retaining sleeves 3 are tightly attached to the first support plate 2; adjust the first support plate 2 and the second support plate 16 to maintain an appropriate distance, which means ensuring that the spring 4 has a compression preload of 15% of its free length, and at the same time ensuring that the non-fixed end of the magnetic wire cutting piece 11 is exactly placed between the two magnetic pieces of the magnet pair 12.

[0034] The vibration absorption process and principle of the rotor dynamic vibration absorber for suppressing axial vibration described above are as follows:

[0035] The axial vibration of the drive shaft is transmitted to the first support plate 2 and the second support plate 16 through double-row tapered roller bearings, and further to the spring 4 for energy storage. Simultaneously, it is transmitted to the magnetic field line cutter 11 and the magnet pair 12. The magnetic damping of the stepped magnetic damping device formed by these two components consumes the vibration energy transmitted from the first support plate 2 and the second support plate 16. The more intense the axial vibration of the drive shaft, the greater the compression of the spring 4, and the more energy is stored. At the same time, the longer the magnetic field line cutter 11 cuts the magnetic field lines of the magnet pair 12, the more energy is consumed by the magnetic damping. The energy of the spring 4 is gradually transferred to the mass unit 7. Meanwhile, the vibration energy not consumed by the magnetic damping is transferred to the mass unit 7 through the magnetic field line cutter 11. The mass unit 7 vibrates axially, while the axial vibration amplitude on the drive shaft is reduced, and the vibration is suppressed to a certain extent.

Claims

1. A rotor dynamic vibration absorber for suppressing axial vibration, characterized in that: It includes a vibration absorber body, a fixed frame, and a guide assembly. The vibration absorber body is connected to the fixed frame through the guide assembly. The guide assembly is arranged parallel to the drive shaft whose vibration is to be suppressed. The vibration absorber body moves along the guide assembly to achieve axial vibration along the drive shaft, thereby suppressing the axial vibration of the drive shaft. The fixed frame is the load-bearing element of the vibration absorber body, including two symmetrically arranged support plates on the left and right. The support plates are support plates with perforated shoulders, and double-row tapered roller bearings are installed in the holes. The drive shaft is mounted on the support plates through the double-row tapered roller bearings. The vibration absorber body includes a mass unit, a linear bearing, and a spring unit and a magnetic damping unit disposed between the mass unit and the support plate. The mass unit is a ring with multiple mounting holes evenly distributed around its circumference. The mounting holes are used to install the linear bearing, and the guide assembly is installed in the inner ring of the linear bearing. The spring unit comprises an even number of springs, with every two springs symmetrically mounted on both sides of the linear bearing between the mass unit and the support plate. The other end of the spring connected to the support plate is embedded in a spring retaining sleeve with a threaded hole, with the side with the smaller pitch closer to the spring retaining sleeve. The side of the spring connected to the mass unit is fixed by a spring washer. The spring is a helical cylindrical spring with unequal pitch. Due to the unequal pitch structure of the spring, its stiffness increases nonlinearly with the amount of compression. The variable stiffness characteristic enables the vibration absorber to have a good vibration absorption effect in the frequency band of ±15% to ±20% of the resonance frequency. The magnetic damping unit includes eight sets of stepped magnetic damping devices, symmetrically installed between the mass unit and the support plate, and evenly distributed along the circumference of the mass unit. Each stepped magnetic damping device includes a magnet, which is cuboid in shape. Each set of stepped magnetic damping devices includes a pair of magnets, which are mounted on the support plate via a magnet fixing plate and evenly installed along the circumference of the first and second support plates. Magnetic field line cutting discs are provided on the mass unit at positions corresponding to the magnet pairs via a cutting disc connecting plate. The magnetic field line cutting discs are of unequal cross-section. When the rotor amplitude is small, the narrow cross-section of the magnetic field line cutting disc cuts the magnetic field lines, generating small damping. When the amplitude is large, the wide cross-section of the cutting disc participates in cutting the magnetic field lines, generating large damping. This damping variation characteristic related to rotor amplitude allows the rotor to have a certain vibration resistance effect when subjected to partial impact, thereby dissipating the energy of slight vibration or strong impact vibration. The guide assembly includes double-ended threaded studs corresponding to the number of mounting holes of the mass unit. The double-ended threaded studs are evenly distributed on the support plate, installed on the inner ring of the linear bearing, and arranged parallel to the drive shaft. The double-ended threaded studs pass sequentially through the first support plate, the spring between the first support plate and the mass unit, the mass unit, the spring between the second support plate and the mass unit, and the second support plate. The threaded ends are fixed to the support plate by hexagonal nuts and spring retaining sleeves with threaded holes.

2. The rotor dynamic vibration absorber for suppressing axial vibration according to claim 1, characterized in that: The spring washer is a helical spring washer, which is fixed to the mass unit by a first external hexagonal bolt.

3. A rotor dynamic vibration absorber for suppressing axial vibration according to claim 2, characterized in that: The spring washer is provided with a first cylindrical locating pin, which is used to cooperate with the first external hexagonal bolt to fix the spring washer.

4. A rotor dynamic vibration absorber for suppressing axial vibration according to claim 1, characterized in that: The magnetic wire cutting sheet has a stepped thickness at the end near the magnet pair, with the cross-section being smaller and the thickness thinner as it gets closer to the magnet pair.

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