Longitudinally-driven slotted annular underwater acoustic transducer

Abstract

The invention relates to the technical field of underwater acoustic transducers, in particular to a longitudinally-driven slotted annular underwater acoustic transducer which comprises a slotted annular shell and a driving vibrator. The slotted ring shell is an annular cylinder, a slot is formed in the wall of the slotted ring shell in the longitudinal axis direction, and the slotted ring shell is in mirror symmetry along the tangent plane of the diameter where the slot is located, so that the slotted ring shell comprises a first shell arm and a second shell arm which are in mirror symmetry. Notches are formed in the inner wall of the slotted ring shell, are in mirror symmetry along the tangent plane of the diameter and are located at the connecting end of the first shell arm and the second shell arm; and the driving vibrator is mounted in the notch and is used for driving the first shell arm and the second shell arm to perform expansion and contraction vibration so as to radiate sound energy into the medium. According to the invention, the rigidity is extremely low, the resonant frequency can be designed in an ultra-low frequency band with a small size, the applicable driving form is wider, the response speed is higher, and the high-power driving linearity is better.

Description

Technical Field

[0001] The invention relates to the technical field of underwater acoustic transducers, and in particular to a longitudinally driven slotted annular underwater acoustic transducer. Background Art

[0002] As we all know, the lower the sound wave frequency, the less its energy is lost in the medium, and the longer the distance it propagates in the ocean. In recent years, the demand for underwater sound wave transmission in the ultra-low frequency band (20Hz~200Hz) has gradually increased. The ultra-low frequency band is mainly used in marine acoustics, including ocean acoustic tomography, ocean temperature measurement, etc. There are also special application requirements such as underwater transponders, underwater target interference, and platform active noise reduction.

[0003] At present, the sound sources in the ultra-low frequency band mainly include electromagnetic, electric, and moving magnetic transducers, as well as air guns, electric sparks, and electromagnetic pulse sound sources. Among them, air guns, electric sparks, and electromagnetic pulse sound sources are explosion sound sources. The sound waves they emit are low-frequency broadband noise. The sound source level is high, but the signal is not editable, and the application prospects are limited. Electromagnetic, electric, and moving magnetic transducers are editable sound sources. They use electromagnetic force to drive the radiating surface to radiate sound waves into the medium. The advantage is that they can emit various forms of pre-edited signals in terms of function. In terms of performance, the resonant frequency is low and the structure is compact. However, electromagnetic force-driven sound sources have problems such as long start-up time, nonlinear electromagnetic force, and unstable deep-water performance, which bring certain troubles to users.

[0004] However, traditional underwater acoustic transducers such as curved disc transducers, flex-tensional transducers, ring transducers, longitudinal vibration transducers and other resonant transducer technologies are difficult to achieve ultra-low frequency band (20Hz ~ 200Hz) transmission capabilities within a smaller size range. Since the eigenfrequency of the resonant transducer is to reach the frequency band range of 20Hz ~ 200Hz, its structural size will exceed the meter level, and the size will double for each frequency reduction, and the manufacturing difficulty will increase exponentially. Therefore, in ultra-low frequency band applications, it is very rare to use traditional resonant transducer technology to achieve it.

[0005] The slotted ring transducer is a resonant transducer that can be used for ultra-low frequency. Initially, the slotted ring transducer was formed by cutting an opening in the height direction of the ring wall of a conventional ring transducer. Researchers found that after the ring was cut, the structural stiffness was greatly reduced. Compared with other traditional transducers of the same size, the resonant frequency can be reduced by 50-80%. Subject to the limitations of the firing process of large-size ring ceramics, as shown in existing information at home and abroad (US8717849, US6678213, US5103130, CN 117460392 A), the subsequent slotted ring transducers almost all use a ceramic strip inlaid ring combined with a slotted metal shell. This type of slotted ring transducer cannot effectively apply prestress to the driving material, greatly reducing the high-power emission potential of the driving material, and also limits the size and shape of the driving material to long strips, square pieces, and other forms suitable for inlay. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the prior art, thereby providing a longitudinally driven slotted annular underwater acoustic transducer, which utilizes a longitudinally driven vibrator 2 to drive the slotted annular shell to expand and contract through longitudinal telescopic vibration, thereby converting electrical energy into underwater sound waves of acoustic energy for emission. The present invention can work in an ultra-low frequency band with a relatively small size and has fast response and resonant emission capabilities.

[0007] In order to solve the above technical problems, the technical solution of the present invention provides a longitudinally driven slotted annular underwater acoustic transducer, comprising: a slotted annular housing and a driving vibrator, wherein:

[0008] The slit ring housing is an annular cylinder, a slit is arranged on its wall along the longitudinal axis, and the slit is mirror-symmetrical along the section of the diameter where the slit is located, so that the slit ring housing includes a mirror-symmetrical first housing arm and a second housing arm;

[0009] The slotted ring housing is provided with a notch on its inner wall, the notch is mirror-symmetrical along the section of the diameter and is located at the connecting end of the first arm of the housing and the second arm of the housing;

[0010] The driving vibrator is installed in the slot to drive the first arm and the second arm of the shell to perform expansion and contraction vibrations, thereby radiating sound energy into the medium.

[0011] As an improvement of the above-mentioned underwater acoustic transducer, the slot includes a first slot and a second slot, the first slot is located on the inner wall of the first arm of the shell, the second slot is located on the inner wall of the second arm of the shell, and the first slot and the second slot are mirror-symmetrical along the cross-section of the diameter and are V-shaped.

[0012] As an improvement of the above-mentioned underwater acoustic transducer, the notch is mirror-symmetrical along the cross-section of the diameter to form a straight line, and is located opposite to the slit.

[0013] As an improvement of the above-mentioned underwater acoustic transducer, the thickness of the first arm of the shell and the thickness of the second arm of the shell gradually decrease from the connecting end to the slit end.

[0014] As an improvement of the above-mentioned underwater acoustic transducer, the driving vibrator includes: two transition blocks and a driving material located between the two transition blocks, wherein the cross-section of the transition block is D-shaped; both sides of the notch respectively have arc-shaped contact surfaces matching the D-shape, and the notch also has a planar contact surface that contacts the driving material.

[0015] As an improvement of the above-mentioned underwater acoustic transducer, the driving material includes at least one magnetostrictive material wrapped by a watertight material in a cylindrical shape; the axial direction of the magnetostrictive material is perpendicular to the longitudinal axial direction, and when multiple magnetostrictive materials are included, the multiple magnetostrictive materials are arranged along the longitudinal axial direction; wherein the magnetostrictive material includes: rare earth giant magnetostrictive material or iron-gallium alloy giant magnetostrictive material.

[0016] As an improvement of the above-mentioned underwater acoustic transducer, the driving material includes at least one piezoelectric material in the shape of a long strip wrapped by a watertight material, and the center line of the piezoelectric material is perpendicular to the longitudinal axis direction. When multiple piezoelectric materials are included, the multiple piezoelectric materials are arranged along the longitudinal axis direction and stacked to form a piezoelectric crystal stack; wherein the piezoelectric material includes: piezoelectric ceramics or relaxor ferroelectric single crystals.

[0017] As an improvement of the above-mentioned underwater acoustic transducer, the material of the slit ring shell includes: metal, carbon fiber or polymer.

[0018] As an improvement of the above-mentioned underwater acoustic transducer, the underwater acoustic transducer also includes: an internal supporting member and a sound-absorbing material; the internal supporting member is cylindrical, and its axis overlaps with the axis of the slit ring shell; the internal supporting member is located in the slit ring shell, and the sound-absorbing material wraps the internal supporting member in the slit ring shell, and the sound-absorbing material does not contact the slit ring shell.

[0019] As an improvement of the above-mentioned underwater acoustic transducer, the underwater acoustic transducer also includes two hanging mounting components and positioning keys; wherein, the slit ring shell is extended out from both ends of the internal supporting component respectively; the two end faces of the slit ring shell are respectively provided with shell connecting parts at positions opposite to the slit; the hanging mounting component is disc-shaped and is provided with a hollow area; the two hanging mounting components are respectively connected to the two ends of the internal supporting component, and are respectively connected to the shell connecting parts through the positioning keys, so that the first arm of the shell and the second arm of the shell are in a suspended state.

[0020] Compared with the prior art, the advantages of the present invention are that the longitudinally driven slotted annular underwater acoustic transducer of the present invention uses a magnetostrictive or electrostrictive material longitudinally driven vibrator to provide driving force, and the slotted ring structure shell is forced to vibrate and radiate sound waves into the medium. The slotted ring shell has extremely low stiffness, and the resonant frequency can be designed in the ultra-low frequency band with a smaller size. Compared with the traditional resonant transducer, it can achieve a smaller size and lower frequency operation; compared with the transducer driven by electromagnetic force, the magnetostrictive or electrostrictive material longitudinally driven vibrator has a shorter start-up time, faster response speed, and more linear response signal; compared with the traditional piezoelectric ceramic spliced ​​ring slotted ring, the longitudinal vibrator driven slotted ring structure has many advantages such as more diverse driving vibrator forms, simpler large-scale assembly process, and easier to apply prestress to the driving material. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1( a ) is a schematic diagram of the main structure of a slotted annular transducer driven in a V” shape;

[0022] FIG1( b ) is a schematic diagram of the main structure of a slotted annular transducer driven in a straight line;

[0023] FIG2( a ) is a detailed view of the main vibration structure of the slotted annular transducer;

[0024] FIG2( b ) is a main body diagram of a slotted annular transducer including internal components;

[0025] FIG3( a ) is an isometric view of the entire transducer;

[0026] FIG3( b ) is a side view of the entire transducer.

[0027] Figure ID

[0028] 1. Slit ring housing 2. Driving vibrator 3. Transition block

[0029] 4. Driving material 5. Sound absorbing material 6. Internal supporting components

[0030] 7. Shell connection part 8. Suspension mounting member 9. Positioning key DETAILED DESCRIPTION

[0031] The technical solution provided by the present invention is further illustrated below in conjunction with embodiments.

[0032] The longitudinally driven slotted annular underwater acoustic transducer provided in this embodiment has a main body including a slotted ring shell 1 and a driving vibrator 2. In addition to the main body, its auxiliary components include a piece of sound absorbing material 5, an internal supporting member 6, two suspension mounting members 8 and two positioning keys 9. When the underwater acoustic transducer is working, an electrical signal is applied to the driving vibrator 2, driving the two arms of the slotted ring shell 1 to expand and contract and vibrate, radiating sound energy into the medium. This structure has the advantages of ultra-low frequency band operation, small size, simple process, high reliability, etc. It is particularly suitable for being mounted on a small platform for low-frequency noise simulation, and can also be installed in a space-constrained location for active noise reduction of the platform.

[0033] The slotted ring housing 1 is in the shape of an annular cylinder. When viewed from the end face, it is an annular structure with a slot cut somewhere along the circumference. The entire housing is bilaterally symmetrical along the slotted section. The "V"-shaped slotted ring housing 1 has a cut notch on each of its left and right arms. The notch centerline of the "I"-shaped slotted ring housing 1 coincides with the symmetry plane. The processed notch is used to place the driving vibrator 2.

[0034] The driving vibrator 2 is composed of a driving material 4 and a transition block 3. The driving material can be divided into two categories. One category is a magnetostrictive material, which is cylindrical and has multiple cylindrical bars arranged along the height direction of the shell. The other category is an electrostrictive material, also called a piezoelectric material. The piezoelectric material can be a rectangular strip, and multiple pieces are stacked to form a piezoelectric crystal stack. The cross section of the transition block 3 is similar to a "D" shape, and the contact surface with the notch of the slotted ring shell 1 is an arc surface, and the contact surface with the active driving material 4 is a plane, which plays a role in transmitting the vibration force and vibration speed excited by the active driving material 4 to the slotted ring shell 1.

[0035] The shape of the sound absorbing material 5 is made into a special-shaped structure according to the inner contour line of the slotted ring shell 1, filling the interior as much as possible, but a certain gap is left between the edge and the inner wall of the slotted ring to avoid affecting the vibration of the shell.

[0036] The internal support member 6 is cylindrical, with a height slightly greater than the slotted ring shell 1 , and is wrapped with a sound absorbing material 5 on the outside and inserted into the slotted ring shell 1 . Threaded holes are provided at both ends for connecting the suspension mounting member 8 .

[0037] The hanging mounting member 8 is disc-shaped in appearance, with an outer diameter equivalent to that of the slotted ring housing 1 , and is hollowed out inside for rapid water inlet. A certain thickness is designed to ensure rigidity and avoid bending due to stress.

[0038] This embodiment includes a set of magnetostrictive or electrostrictive materials with faster response speed to provide driving force for longitudinal driving vibrators 2; it also includes a low-rigidity slotted ring housing 1, in which the driving vibrator 2 is embedded in a reserved groove in a "V" or "I" shape to form a slotted ring main vibration structure with a resonance frequency in the ultra-low frequency band. It also includes auxiliary components such as a suspension mounting member 8, an internal support member 6, and a sound absorbing material 5 to realize a transducer device with a suspension mounting function.

[0039] The magnetostrictive or electrostrictive material longitudinal driving vibrator 2 can be a single rod or multiple rods longitudinal vibration driving vibrator 2 made of rare earth giant magnetostrictive material or iron-gallium alloy giant magnetostrictive material, or it can be a driving crystal stack made of piezoelectric ceramics, relaxor ferroelectric single crystals and other electrostrictive materials.

[0040] The low-rigidity slotted ring shell 1 is a ring-shaped structure that is disconnected in the middle. Its material can be metal or non-metallic materials such as carbon fiber and polymer. The ring body is processed by modern processing methods to form a groove in which the driving vibrator 2 can be embedded, so as to embed the above-mentioned driving vibrator 2.

[0041] The low-rigidity slotted ring housing 1 can be stretched open by applying pressure to the two arms of the housing, so that the length of the groove is extended. After the driving vibrator 2 is embedded, the pressure of the two arms is released, and the driving vibrator 2 is squeezed by the rebound force of the housing to provide prestress for it. Compared with the traditional ceramic slotted ring, this structure can more conveniently provide controllable prestress for the driving material, so that the linear driving range of the transducer is larger.

[0042] The low-rigidity slotted ring shell 1 has a vibration node position at the midline of the two arms. This position has a small displacement when the shell is in a vibration state and has a strong ability to resist external interference, and can be used to install auxiliary components.

[0043] The suspension mounting component 8 is arranged at each of the upper and lower end surfaces of the main vibration structure, and is connected to the vibration node position of the low-rigidity slit ring shell 1 by bolts. When designing and installing, a certain size of gap should be reserved between the suspension mounting component 8 and the end surface of the low-rigidity slit ring shell 1. This gap provides free mechanical boundary conditions for the two arms of the low-rigidity slit ring shell 1, thereby preventing the slit ring main vibration structure from being affected by changes in boundary conditions, resulting in negative effects such as performance degradation and frequency shift.

[0044] The internal support member 6 is placed inside the ring body and connected between the two suspension mounting members 8 by bolts. Since the suspension mounting member 8 can only be installed at a single point at the node position of the shell and maintain a certain gap with the shell, a cantilever beam structure is formed with low rigidity. The internal support member 6 connects the two suspension mounting members 8 to form a four-point connection, which improves the rigidity of the entire auxiliary mounting member and is beneficial to the overall installation and hanging of the transducer.

[0045] The sound-absorbing material 5 can be a porous sound-absorbing material 5 or a resonant sound-absorbing material 5. Wrapping the material around the internal support member 6 and filling the inside of the ring body can achieve the effect of absorbing the inwardsound energy of the slotted ring, thereby reducing the phenomenon of "acoustic short circuit" of the slotted ring and improving the sound radiation ability of the slotted ring transducer.

[0046] This embodiment overcomes the problems of difficult prestress application and complex process of traditional piezoelectric ceramic slotted rings, simplifies the prestress application method, and improves the process reliability.

[0047] This embodiment overcomes the problem of a single driving element in traditional piezoelectric ceramic slotted rings, provides a new structural form of applying a "longitudinal oscillator" to a slotted ring transducer, and expands the technical approach for applying more excellent driving elements such as rare earth giant magnetostrictive materials and relaxor ferroelectric single crystals to this structure.

[0048] This embodiment can be used to simulate low-frequency noise on a small platform or installed in a space-constrained location for platform active noise reduction.

[0049] The following further describes this embodiment with reference to the accompanying drawings.

[0050] Referring to FIG. 1, the main structure of the slotted ring transducer can be "V"-shaped ( Figure 1a ) or "-"-shaped ( Figure 1b ), and its main structure is composed of a low-stiffness slotted ring housing 1 and a driving oscillator 2. Among them, the low-stiffness slotted ring housing 1 is circular in shape when viewed from the end face, and is designed as an opening structure at a certain position along the circle. The whole housing is symmetric left and right, so that the slotted ring housing 1 includes a mirror-symmetric housing first arm and housing second arm.

[0051] The slotted ring housing 1 is provided with a notch on its inner wall. The notch is mirror-symmetric along the section of the diameter and is located at the connecting end of the housing first arm and the housing second arm; the driving oscillator 2 is installed in the notch to drive the housing first arm and the housing second arm to expand and contract, so as to radiate sound energy into the medium.

[0052] The thicknesses of the housing first arm and the housing second arm gradually decrease from their connecting ends to the slotted ends. This design can reduce the co-vibration mass of the thicknesses of the housing first arm and the second arm, and thus reduce the mechanical Q value, that is, the quality factor, thereby improving the bandwidth.

[0053] In one embodiment, the notch includes a first notch and a second notch. The first notch is located on the inner wall of the housing first arm, and the second notch is located on the inner wall of the housing second arm. The first notch and the second notch are mirror-symmetric along the section of the diameter and are in a "V" shape. The "V"-shaped slotted ring housing 1 is as Figure 1aIn another embodiment, the notch is mirror-symmetrical along the cross section of the diameter and is located opposite to the slit. Figure 1b shown.

[0054] "V" shaped slotted ring housing 1 ( Figure 1a ) a cutting notch on each side, a "I" shaped slit ring housing 1 ( Figure 1b ) has a groove centerline that coincides with the symmetry plane, and the processed groove is used to place the driving vibrator 2.

[0055] The driving vibrator 2 is in the shape of a long strip when viewed from the end face, with the outer surface covered by a watertight material and the interior being an active driving material 4. The length of the driving vibrator 2 should be slightly longer than the length of the slot. Applying an outward pulling force to the two arms of the slit ring shell 1 can increase the length of the slot. After the driving vibrator 2 is inserted into the slot, the pulling force on the two arms is released, and the driving vibrator 2 is clamped by relying on the resilience of the material of the slit ring shell 1.

[0056] Referring to Figure 2, Figure 2 (a) is a detailed view of the main vibration structure, and the driving vibrator 2 is composed of transition blocks 3 at both ends and an internal active driving material 4. The transition block 3 has an arc surface in contact with the notch of the slotted ring housing 1, and a plane surface in contact with the internal active driving material 4, which serves to transmit the vibration force and vibration speed excited by the internal active driving material 4 to the slotted ring housing 1; the internal active driving material 4 can be arranged in multiple groups of cylinders or can be a cuboid, which is designed according to the characteristics of the active material.

[0057] Referring to Figure 2, Figure 2(b) shows the main body including the internal components, including the slotted ring shell 1, the driving vibrator 2, the sound absorbing material 5, the internal support member 6, and the shell connection part 7. Among them, the internal support member 6 is located at the center of the main vibration structure of the slotted ring transducer, and the height of the internal support member 6 in the axial direction is a certain size higher than the slotted ring shell 1; the sound absorbing material 5 is made into a special-shaped structure along the inner shape of the slotted ring shell 1, wrapped on the outer side of the internal support member 6, and kept a certain distance from the inner wall of the slotted ring shell 1 to avoid affecting the vibration of the shell; the shell connection part 7 is actually a keyway, and two threaded holes are provided for connecting the suspension mounting component 8.

[0058] Referring to FIG3 , the transducer as a whole includes a suspension mounting component 8 and a positioning key 9 in addition to the main structure. The suspension mounting component 8 is a fulcrum for external installation and hanging. It is positioned and connected through the positioning key 9 and the shell connection part 7 on the slit ring shell 1; the two suspension mounting components 8 on the two end surfaces are connected through the internal support component 6. The internal support component 6 is a certain size higher than the slit ring shell 1 in the axial direction, so that the two arms of the slit ring shell 1 are in a suspended state. In this way, when the slit ring transducer is working, the two arms of the slit ring shell 1 expand and contract under the telescopic drive of the driving vibrator 2, radiating sound energy outward, and the sound absorbing material 5 plays a role in absorbing the inward sound energy. The auxiliary structures such as the internal support component 6, the suspension mounting component 8, the positioning key 9 and the shell connection part 7 hardly vibrate, and play a role in external installation, hanging, and protecting the main structure.

[0059] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A longitudinally driven slotted annular hydroacoustic transducer, comprising: A slotted ring housing and a driving vibrator, wherein: The slit ring housing is an annular cylinder, a slit is arranged on its wall along the longitudinal axis, and the slit is mirror-symmetrical along the section of the diameter where the slit is located, so that the slit ring housing includes a mirror-symmetrical first housing arm and a second housing arm; The slotted ring housing is provided with a notch on its inner wall, the notch is mirror-symmetrical along the section of the diameter and is located at the connecting end of the first arm of the housing and the second arm of the housing; The driving vibrator is installed in the slot to drive the first arm and the second arm of the shell to perform expansion and contraction vibrations, thereby radiating sound energy into the medium.

2. The longitudinally driven slotted annular hydroacoustic transducer according to claim 1, characterized in that: The notch includes a first notch and a second notch, the first notch is located on the inner wall of the first arm of the shell, the second notch is located on the inner wall of the second arm of the shell, and the first notch and the second notch are mirror-symmetrical along the cross section of the diameter and are V-shaped.

3. The longitudinally driven slotted annular hydroacoustic transducer according to claim 1, characterized in that: The notch is mirror-symmetrical along the section of the diameter to form a straight line, and is located opposite to the slit.

4. The longitudinally driven slotted annular hydroacoustic transducer according to claim 1, characterized in that: The thickness of the first arm of the shell and the thickness of the second arm of the shell gradually decrease from the connecting end to the slot end.

5. The longitudinally driven slotted annular hydroacoustic transducer according to claim 1, characterized in that: The driving vibrator comprises: two transition blocks and a driving material located between the two transition blocks, wherein the cross section of the transition block is D-shaped; Both sides of the notch are provided with arc-shaped contact surfaces matching the D-shape, and the notch is also provided with a plane contact surface contacting with the driving material.

6. The longitudinally driven slotted annular hydroacoustic transducer according to claim 5, characterized in that: The driving material comprises at least one magnetostrictive material wrapped by a watertight material in a cylindrical shape; the axis direction of the magnetostrictive material is perpendicular to the longitudinal axis direction; when multiple magnetostrictive materials are included, the multiple magnetostrictive materials are arranged along the longitudinal axis direction; wherein, The magnetostrictive material includes: rare earth giant magnetostrictive material or iron-gallium alloy giant magnetostrictive material.

7. The longitudinally driven slotted annular hydroacoustic transducer according to claim 5, characterized in that: The driving material includes at least one piezoelectric material wrapped by a watertight material in a long strip shape, the center line of the piezoelectric material is perpendicular to the longitudinal axis direction, and when multiple piezoelectric materials are included, the multiple piezoelectric materials are arranged along the longitudinal axis direction and stacked to form a piezoelectric crystal stack; wherein, The piezoelectric material includes: piezoelectric ceramics or relaxor ferroelectric single crystals.

8. The longitudinally driven slotted annular hydroacoustic transducer according to claim 1, characterized in that: The materials of the slotted ring housing include: metal, carbon fiber or polymer.

9. The longitudinally driven slotted annular hydroacoustic transducer according to claim 1, characterized in that: Also includes: An internal support member and a sound absorbing material; the internal support member is cylindrical, and its axis overlaps with the axis of the slotted ring shell; The internal supporting member is located in the slit ring shell, the sound absorbing material wraps the internal supporting member in the slit ring shell, and the sound absorbing material does not contact the slit ring shell.

10. The longitudinally driven slotted annular hydroacoustic transducer according to claim 1, characterized in that: It also includes two hanging installation components and positioning keys; wherein, Both ends of the internal support member extend out of the slotted ring housing respectively; The two end surfaces of the slit ring housing are respectively provided with housing connection parts at positions opposite to the slit; The suspension installation member is in the shape of a disk and is provided with a hollow area; The two suspension installation components are respectively connected to the two ends of the internal support component, and are respectively connected to the shell connecting part through positioning keys, so that the first arm of the shell and the second arm of the shell are in a suspended state.

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