A Magnetostrictive Bending Cylindrical Transducer with Shell Conformal Driving and Its Preparation Method

Abstract

The present invention discloses a magnetostrictive bending cylindrical transducer driven by shell conformal and a preparation method thereof, which includes an open cylindrical shell, and the open cylindrical shell is a thin-walled cylindrical shell slotted along the generatrix direction; an open driving assembly, the driving assembly is located inside the open cylindrical shell and is arranged in contact with the inner wall of the open cylindrical shell, the open driving assembly includes an unclosed active element, the active element is made of a giant magnetostrictive material, the active element is wound with a coil, there are multiple active components and they are stacked up and down, and magnetic conduction blocks are respectively arranged at both ends of the multiple active elements stacked up and down, and together with the coil and the magnetic conduction blocks, a closed magnetic circuit is formed. The structure of the present invention is simple and easy to implement, the technological process is simple and controllable, and at the same time, it has a lower weight.

Description

Technical Field:

[0001] The present invention relates to the technical field of underwater acoustic transducers, and particularly to a magnetostrictive bending cylindrical transducer with conformal driving of a housing and a preparation method thereof. Background Art:

[0002] An underwater acoustic transducer is an important device for generating or receiving acoustic wave signals in a sonar system, and its main function is to realize the mutual conversion between electrical energy and acoustic energy. A transducer that converts electrical energy into acoustic energy and radiates it into water is called a transmitting transducer, while a transducer that converts received acoustic energy into electrical energy is called a receiver or hydrophone. Generally, a transducer has reciprocity and can be used both for transmission and reception.

[0003] Low-frequency acoustic waves have the characteristics of low absorption coefficient and long propagation distance in water. Therefore, to improve the long-range detection ability of a sonar, the operating frequency of its transducer must be extended to the low frequency. Chinese Patent CN201510662142.9 describes a low-frequency small-size slotted ring transducer driven by a giant magnetostrictive material. It constructs a non-closed polygonal driving structure through a giant magnetostrictive material rod, and uses the longitudinal vibration of the giant magnetostrictive material rod to push the bending vibration of the housing, and then radiates acoustic waves outward. The advantages of this technology are that compared with the traditional piezoelectric ceramic mosaic bar scheme, the magnetostrictive driving method adopted can obtain a larger vibration displacement output, and at the same time, the driving structure is simpler and easier to realize in the process. However, since the driving material is rod-shaped, a transition structure is required between the active material of the transducer and the housing to transmit the vibration displacement, which increases the structural complexity of the transducer. At the same time, the end face of the driving material is connected to the transition structure, and the contact area is small, so the transducer has poor resistance to hydrostatic pressure and vibration stress. Summary of the Invention:

[0004] The technical problem to be solved by the present invention is to provide a magnetostrictive bending cylindrical transducer with conformal driving of a housing and a preparation method thereof, which has a simple structure and is easy to realize, the process is simple and controllable, and at the same time has a lower weight.

[0005] The technical solution of the present invention is to provide a magnetostrictive bending cylindrical transducer with conformal driving of a housing, including

[0006] An open cylindrical shell, which is a thin-walled cylindrical shell slotted along the generatrix direction;

[0007] An open driving assembly, which is located inside the open cylindrical shell and is arranged in contact with the inner wall of the open cylindrical shell. The open driving assembly includes an unclosed active element made of a giant magnetostrictive material. A coil is wound around the active element. There are multiple active components stacked up and down. Magnetic conduction blocks are respectively arranged at both ends of the multiple stacked active elements up and down, and together with the coil and the magnetic conduction blocks, a closed magnetic circuit is formed;

[0008] Among them, the opening drive component drives the opening cylindrical shell to generate bending vibration through longitudinal vibration and bending vibration, and then promotes the water medium to generate vibration and radiate low-frequency sound waves. When the bending cylindrical transducer is in water, low-frequency radiation sound waves are generated.

[0009] Preferably, the active element is composed of a straight active element in the middle and curved active elements symmetrically distributed on both sides of the straight active element.

[0010] Preferably, positioning holes for fixing the magnetic conduction block and mounting holes for mounting the tooling fixture are provided near the opening of the opening cylindrical shell.

[0011] Preferably, the magnetic conduction block is generally made of a material with high magnetic permeability such as pure electrical iron. Its cross-section is a sector with a uniform thickness or a thick thickness at the connection of the curved active element and a thin thickness near the opening. The height of the magnetic conduction block is not less than the vertical distance between the two curved active elements at the top and bottom, and not greater than the height of the opening cylindrical shell, that is, it should be ensured that it can be in full contact with the upper and lower two curved active elements and can be at most as high as the cylindrical shell.

[0012] Preferably, the coil is wound around a wire hoop with enameled wire or a wire with an insulated outer surface and fixed in the middle outside the straight active element. The wire hoop is generally made of a lightweight non-metallic material such as epoxy board or polytetrafluoroethylene, which plays a role in restricting the shape of the coil.

[0013] Preferably, the opening cylindrical shell is a thin-walled cylindrical shell with a slot along the generatrix direction. Its cross-section has a uniform wall thickness or a gradually changing wall thickness with a thin slot and a thick thickness opposite the slot; its material is a metal material such as aluminum, stainless steel or titanium alloy, or a high-strength non-metallic material such as carbon fiber or glass fiber.

[0014] In the present invention, the magnetic conduction block, the coil, the straight active element and the curved active element form a magnetic conduction loop. Among them, an alternating current passes through the coil to generate an alternating magnetic field, and a direct current passes through the coil to generate a bias magnetic field, so that the straight active element and the curved active element generate alternating vibration displacements near the optimal working point. The coil can be wound with enameled wire. The wire diameter is determined according to the space size and the maximum design current. A single coil can be wound with a single enameled wire. When working, an alternating current with a bias is loaded. A single coil can also be wound with two enameled wires in the same direction. When working, one wire is loaded with an alternating current and the other wire is loaded with a direct current; the straight active element and the curved active element are giant magnetostrictive materials, generally giant magnetostrictive materials with a relatively high magnetic permeability such as iron-gallium alloy.

[0015] The present invention also provides a preparation method for the magnetostrictive bending cylindrical transducer with the above-mentioned conformal drive of the housing, including the following steps,

[0016] Step 1: Uniformly wind the enameled wire around the polytetrafluoroethylene wire hoop and fix the coil at the center of the linear active element.

[0017] Step 2: Place positioning pads inside the open cylindrical shell to support and fix the active element in the height direction of the open cylindrical shell. Then, place the linear active element with the coil on the positioning pads, and the centers of the coil and the linear active element are aligned with the opening of the open cylindrical shell.

[0018] Step 3: Then, place the curved active elements on both sides of the linear active element respectively. Next, place the magnetic conduction block beside the end face of the curved active element close to the opening of the open cylindrical shell. The magnetic conduction block, the linear active element, and the curved active element are all in contact with the inner wall of the open cylindrical shell. Place another set of positioning pads above the linear active element and the curved active element, and then place the linear active element and the curved active element of the second layer. Moreover, epoxy resin glue is applied to the mutually contacting surfaces between all the open cylindrical shells, magnetic conduction blocks, linear active elements, and curved active elements before installation.

[0019] Step 4: After assembling the open driving assembly and the open cylindrical shell, use a tooling fixture to tighten the driving structure composed of multiple layers of open driving assemblies, so that there is a prestress for the shell to contract inward.

[0020] Step 5: Wait for the epoxy resin glue between the expanded driving structure and the open cylindrical shell to cure. Machine a threaded hole on the magnetic conduction block through the positioning hole, and pass a screw through the positioning hole and tighten it with the thread in the magnetic conduction block to fix the relative position of the open cylindrical shell and the magnetic conduction block.

[0021] Step 6: Finally, remove the tooling fixture. At this time, the open cylindrical shell contracts inward, applying prestress to the driving structure.

[0022] After adopting the above scheme, compared with the prior art, the present invention has the following advantages:

[0023] Compared with the flextensional transducer and the flexural disk transducer, the present invention greatly reduces the volume and weight of the transducer at the same working frequency, improving the installability and usability of the small platform sonar. Using the Galfenol giant magnetostrictive material to drive the transducer, first, the magnetic permeability of Galfenol is much greater than that of Terfenol-D material, and the magnetic field required to drive the vibration of Galfenol is much smaller than that of Terfenol-D material. Therefore, the current loaded on the coil is small and the coil loss is small. Second, Galfenol has good machinability and high magnetic permeability, which plays both a driving role and a magnetic conduction role in the transducer. The multiplexing of functions makes the internal driving structure of the transducer simple and the process easy to implement, and also reduces the mass of the driving structure. Third, the driving structure is closely combined with the shell with a high degree of integration, increasing the internal stability during the vibration of the transducer. Description of the Drawings:

[0024] Figure 1 It is a schematic structural diagram of the vibrating component of a flexural cylindrical transducer.

[0025] Figure 2 It is a schematic diagram of the vibration mode of a flexural cylindrical transducer.

[0026] Figure 3 It is a schematic diagram of the magnetic flux conduction direction of a flexural cylindrical transducer.

[0027] Figure 4 It is a schematic diagram of the vibration mode of the housing of a flexural cylindrical transducer. Specific implementation manner:

[0028] The following further describes the present invention in conjunction with the accompanying drawings with respect to the specific implementation manner:

[0029] A driving structure of a flexural cylindrical transducer provided by the present invention is as Figure 1 shown, including

[0030] An open cylindrical shell 1, which is a thin-walled cylindrical shell grooved along the generatrix direction;

[0031] An open driving assembly, which is located inside the open cylindrical shell 1 and is arranged in contact with the inner wall of the open cylindrical shell 1. The open driving assembly includes an unclosed active element, and the active element is made of a giant magnetostrictive material. A coil 4 is wound around the active element. There are multiple active components arranged in upper and lower layers. Magnetic conduction blocks 2 are respectively arranged at both ends of the multiple vertically stacked active elements, and together with the coil 4 and the magnetic conduction blocks 2, they form a closed magnetic circuit; specifically, the active element is composed of a linear active element 5 in the middle and arc-shaped curved active elements 6 symmetrically distributed on both sides of the linear active element 5. The giant magnetostrictive material uses an iron-gallium alloy, which has the characteristics of high magnetic permeability and strong machinability. Therefore, it can be processed into a structure conformal to the transducer housing, enabling the giant magnetostrictive material in the transducer to simultaneously play the roles of driving and magnetic conduction, enhancing the structural compactness of the transducer, and enhancing the hydrostatic pressure resistance and vibration stability of the transducer.

[0032] Among them, the open driving assembly drives the open cylindrical shell 1 to generate bending vibration through longitudinal vibration and bending vibration, and then pushes the water medium to generate vibration and radiate low-frequency sound waves. When the flexural cylindrical transducer is in water, it generates low-frequency radiated sound waves.

[0033] In this embodiment, the open cylindrical shell 1 is made of duralumin. The thinnest part is at the opening of the housing, and the thickest part is at the position directly opposite to the opening. The thickness of the housing linearly increases from the thinnest part to the thickest part. The magnetic conduction block 2 is made of pure electrical iron, with the same height as the open cylindrical shell 1, and the cross-section is a sector with variable thickness. The wire hoop 3 is made of polytetrafluoroethylene and plays the role of installing, positioning, and shaping the coil 4. The coil 4 is wound with enameled wire. Both the linear active element 5 and the curved active element 6 are made of iron-gallium alloy.

[0034] In this embodiment, the preparation can be carried out in the following manner. First, the enameled wire is evenly wound around the polytetrafluoroethylene wire hoop 3. Then, the coil 4 is fixed at the center of the linear active element 5.

[0035] Positioning pads are placed inside the open cylindrical shell 1 to support and fix the active element in the height direction of the open cylindrical shell 1. Then, the linear active element 5 equipped with the coil 4 is placed on the positioning pads, and the centers of the coil 4 and the linear active element 5 are aligned with the opening of the open cylindrical shell 1. Then, the curved active elements 6 are respectively placed on both sides of the linear active element 5, and then the magnetic conduction block 2 is placed beside the end face of the curved active element 6 close to the opening of the open cylindrical shell 1. The magnetic conduction block 2, the linear active element 5, and the curved active element 6 are all in contact with the inner wall of the open cylindrical shell 1. Another set of positioning pads is placed above the linear active element 5 and the curved active element 6, and then the second-layer linear active element 5 and the curved active element 6 are placed. Epoxy resin glue is applied to the mutually contacting surfaces between all the open cylindrical shells 1, the magnetic conduction blocks 2, the linear active elements 5, and the curved active elements 6 before installation.

[0036] Since it is necessary to apply prestress to the drive structure composed of multiple layers of open drive components through the open cylindrical shell 1, after the drive structure and the housing are assembled, the drive structure is tightened by a tooling fixture, so that the housing has an inward contraction prestress.

[0037] Wait for the epoxy resin glue between the drive structure composed of multiple layers of open drive components that has been expanded and the housing to cure. Threaded holes are machined on the magnetic conduction block 2 through the positioning holes 7, and screws are passed through the positioning holes 7 and tightened with the threads in the magnetic conduction block 2 to fix the relative positions of the open cylindrical shell 1 and the magnetic conduction block 2. Finally, the tooling fixture is removed. At this time, the housing contracts inward, applying prestress to the drive structure.

[0038] The vibration mode of this kind of vibration component is as Figures 2-4 shown. Its working principle is: The coil 4 generates a constant magnetic field under the excitation of direct current, and this magnetic field makes the linear active element 5 and the curved active element 6 in a suitable working point. At the same time, the coil 4 generates an alternating magnetic field under the excitation of alternating current, and the direction of the magnetic force lines in the magnetic field is generally as shown by the solid arrows in Figure 3 . According to the magnetostrictive characteristics of the curved active element 6, it will generate alternating strain in the alternating magnetic field. The linear active element 5 and the curved active element 6 expand and contract in the direction shown by the hollow arrows in Figure 3 . The vibration directions of each mirror-symmetrical active element are also mirror-symmetrical. The multi-layer open drive component composed of the magnetic conduction block 2, the linear active element 5, and the curved active element 6 pushes the open cylindrical shell 1 to generate bending vibration, and the vibration mode of the housing is as Figure 3As shown. To ensure the magnetic circuit closing condition and the uniformity of the vibration distribution in the height direction of the open cylindrical shell 1, the multi-layer open driving structure should at least include two layers, and a relatively high parallelism and concentricity are required between them to ensure the consistency of the vibration phase and improve the effective coupling coefficient.

[0039] The above description is only for the preferred embodiments of the present invention, but it should not be construed as a limitation to the claims. Any equivalent structure or equivalent process transformation made using the specification of the present invention is included within the scope of the patent protection of the present invention.

Claims

1. A magnetostrictive bending cylindrical transducer driven by a conformal shell, characterized in that: Comprising An open cylindrical shell, which is a thin-walled cylindrical shell grooved along the generatrix direction; An open driving assembly, which is located inside the open cylindrical shell and is arranged in contact with the inner wall of the open cylindrical shell. The open driving assembly includes an unclosed active element made of a giant magnetostrictive material. The active element is wound with a coil. There are multiple active components stacked up and down. Magnetic conduction blocks are arranged at both ends of the multiple stacked active elements up and down, and together with the coil and the magnetic conduction blocks, a closed magnetic circuit is formed; Among them, the open driving assembly drives the open cylindrical shell to generate bending vibration through longitudinal vibration and bending vibration, and then promotes the water medium to generate vibration and radiate low-frequency sound waves; The active element is composed of a straight active element in the middle and curved active elements symmetrically distributed on both sides of the straight active element.

2. The magnetostrictive bending cylindrical transducer with conformal driving of the housing according to claim 1, wherein: The open cylindrical shell is provided with positioning holes for fixing the magnetic conduction blocks and mounting holes for mounting tooling jigs near the opening.

3. The magnetostrictive bending cylindrical transducer with conformal driving of the housing according to claim 1, wherein: The cross-section of the magnetic conduction block is a sector with a uniform thickness or a thick thickness at the connection with the curved active element and a thin thickness near the opening. The height of the magnetic conduction block is not less than the vertical distance between the two curved active elements at the top and bottom, and is not greater than the height of the open cylindrical shell.

4. The shell-conformal-driven magnetostrictive bending cylindrical transducer according to claim 2, characterized in that: The magnetic conduction block is fixed at the relative position of the open cylindrical shell through the positioning hole to maintain the prestress on the straight active element and the curved active element.

5. The shell-conformal-driven magnetostrictive bending cylindrical transducer according to claim 1, characterized in that: The coil is wound with enameled wire or a wire with an insulated outer surface on a wire hoop and fixed in the middle outside the straight active element.

6. The shell conformal drive magnetostrictive bending cylindrical transducer according to claim 1, wherein: The open cylindrical shell is a thin-walled cylindrical shell grooved along the generatrix direction, with a uniform wall thickness in cross-section, or a gradually changing wall thickness with a thin groove and a thick thickness opposite the groove; its material is aluminum, stainless steel or titanium alloy material, or carbon fiber, glass fiber material.

7. A preparation method of a shell conformal driving magnetostrictive bending cylindrical transducer as described in claim 1, characterized in that: Including the following steps Step 1: Uniformly wind the enameled wire on a polytetrafluoroethylene wire hoop and fix the coil at the center of the straight active element; Step 2: Place positioning pads inside the open cylindrical shell, and then place the straight active element with the coil installed on the positioning pads. The centers of the coil and the straight active element are aligned with the opening of the open cylindrical shell; Step 3: Then place the curved active elements on both sides of the straight active element respectively, and then place the magnetic conduction blocks beside the end faces of the curved active elements near the opening of the open cylindrical shell. The magnetic conduction blocks, the straight active element, and the curved active elements are all in contact with the inner wall of the open cylindrical shell. Place another set of positioning pads above the straight active element and the curved active elements, and then place the straight active element and the curved active elements of the second layer. Moreover, epoxy resin glue is applied to the mutually contacting surfaces of all the open cylindrical shells, magnetic conduction blocks, straight active elements, and curved active elements before installation; Step 4: After assembling the open driving assembly and the open cylindrical shell, tighten the driving structure composed of multiple layers of open driving assemblies through tooling jigs to make the shell have an inward contraction prestress; Step 5: Wait for the epoxy resin glue between the expanded driving structure and the open cylindrical shell to cure, process threaded holes on the magnetic conduction blocks through the positioning holes, and tighten the screws through the positioning holes and the threads in the magnetic conduction blocks to fix the relative positions of the open cylindrical shell and the magnetic conduction blocks; Step 6. Finally, remove the tooling fixture. At this time, the open cylindrical shell contracts inward, and prestress is applied to the driving structure.

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