CN113909083B - Piezoelectric-Electromagnetic Hybrid Driven Dipole Acoustic Transducer - Google Patents

Abstract

The invention relates to the technical field of acoustic wave transducers, in particular to a piezoelectric-electromagnetic hybrid drive type dipole acoustic wave transducer. The permanent magnet; the cylindrical shell comprises a cylindrical bracket and two insulators, wherein two ends of the cylindrical bracket are respectively connected with the two outer end covers; the cylindrical support is made of a conductive material; the two insulators are oppositely arranged and are arranged on the cylindrical shell at positions far away from the two permanent magnets. The invention improves the structure of the existing transducer on the basis of the piezoelectric drive with limited strain of the piezoelectric ceramics, and realizes the hybrid drive of two effects by adding the electromagnetic drive, and the vibration amplitude of the cylindrical shell is improved by the hybrid drive, thereby enhancing the sound wave intensity and improving the detection distance.

Description

Piezoelectric-Electromagnetic Hybrid Driven Dipole Acoustic Transducer

technical field

The invention relates to the technical field of acoustic wave transducers, in particular to a piezoelectric-electromagnetic hybrid-driven dipole acoustic wave transducer.

Background technique

With the massive exploitation of oil and gas, logging technology has developed rapidly. Among them, the dipole acoustic wave logging technology is widely used, for example, the dipole acoustic wave can be used to calculate various elastic constants of the rock, and it can effectively identify the gas and fractures of the oil and gas reservoir, and analyze the rock structure. With the continuous exploitation of oil and gas, the logging distance that needs to be achieved is getting larger and larger. How to improve the distance of ultrasonic logging is particularly important.

Cylindrical piezoelectric oscillating acoustic transducer is one of the most widely studied acoustic transducers. The cylindrical piezoelectric oscillating acoustic wave transducer is composed of three laminations, metal skeleton, spring, cylindrical shell and so on. The tri-laminate consists of a metal substrate and piezoelectric devices on both sides. In the piezoelectric device principle, a sinusoidal voltage is applied to the side of the metal substrate, and one side of the metal substrate is grounded. Under the action of the excitation voltage, the tri-laminate will deform, and then drive the cylindrical shell to swing and contact the medium in the well. produce sound waves.

Existing dipole acoustic wave transducers are piezoelectrically driven, which can present a relatively pure dipole acoustic field. Although cylindrical piezoelectric swing acoustic wave transducers can generate acoustic waves well, they have been used in logging well in the past. However, due to the limited strain of the piezoelectric ceramic itself, the vibration amplitude of the cylindrical shell is small, the intensity of the generated sound wave will not be too strong, and the detection distance is limited. However, with the increase of logging distance requirements, the acoustic wave intensity generated by the cylindrical piezoelectric pendulum acoustic transducer cannot achieve the desired effect.

Therefore, there is an urgent need for a dipole acoustic wave transducer that can increase the vibration amplitude of the cylindrical shell and increase the detection distance.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is that, in view of the problem that the vibration amplitude of the existing dipole acoustic wave transducer involved in the background technology is small, on the basis of the original piezoelectric drive The above is driven by electromagnetic drive to realize the mixed drive of the dipole acoustic wave transducer and increase the vibration amplitude of the dipole acoustic wave transducer.

The technical scheme adopted by the present invention to achieve the above purpose is: a piezoelectric-electromagnetic hybrid-driven dipole acoustic wave transducer, comprising two oppositely arranged outer end caps, a cylindrical shell arranged between the two outer end caps magnet and two permanent magnets, the two permanent magnets are symmetrically arranged on both sides of the cylindrical shell;

The cylindrical shell comprises a cylindrical support whose ends are respectively connected with two outer end caps, and two insulators fixed on the cylindrical support;

the cylindrical support is made of conductive material;

The two insulators are arranged opposite to each other, and are arranged on the cylindrical shell at a position away from the two permanent magnets.

Further, the cylindrical bracket includes two inner end caps respectively connected with the two outer end caps, and two supporting brackets arranged between the two inner end caps, the two supporting brackets are arranged opposite to each other and are respectively It is located on the cylindrical support near the two permanent magnets.

Further, the two insulators and the two support frames are interspersed and arranged at intervals.

Further, the two inner end caps, the two support frames and the two insulators together form a fully enclosed cylindrical shell.

Further, the two permanent magnets are oppositely disposed on the right and left sides of the cylindrical shell.

Further, two sets of three laminations connected between the two inner end caps are arranged inside the cylindrical shell.

Further, the three-layered sheet includes a metal substrate, two piezoelectric ceramic sheets respectively arranged on both sides of the metal substrate, the two ends of the metal substrate are respectively connected with the two inner end caps, and the metal The positive and negative electrodes of the excitation voltage are respectively connected to the substrate and the piezoelectric ceramics.

Further, the positive and negative electrodes of the excitation current are respectively connected to the two inner end caps.

Further, a U-shaped spring is arranged between the inner end cover and the outer end cover.

Further, the permanent magnets are prism-shaped, the opposite surfaces of the two permanent magnets are parallel to each other, and the insulators are sector-shaped and made of carbon fibers.

The beneficial effects of the piezoelectric-electromagnetic hybrid-driven dipole acoustic wave transducer of the present invention are:

The invention improves the existing transducer structure on the basis of piezoelectric drive with limited strain of piezoelectric ceramic itself, adds electromagnetic drive, realizes the mixed drive of the two effects, and improves the vibration amplitude of the cylindrical shell through the mixed drive , enhance the sound wave intensity and improve the detection distance.

Description of drawings

Fig. 1 is the front view structure schematic diagram of the embodiment of the present invention;

Fig. 2 is a side view structural schematic diagram of an embodiment of the present invention;

FIG. 3 is a top-view structural schematic diagram of an embodiment of the present invention;

4 is a schematic side sectional view of a permanent magnet removed according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of three laminations according to an embodiment of the present invention;

6 is a schematic structural diagram of a U-shaped spring according to an embodiment of the present invention;

7 is a schematic structural diagram of a permanent magnet according to an embodiment of the present invention;

8 is a schematic structural diagram of an outer end cap according to an embodiment of the present invention;

9 is a schematic structural diagram of a cylindrical support according to an embodiment of the present invention;

10 is a schematic diagram of a B-B cross-sectional structure of an embodiment of the present invention;

11 is a schematic top view of a cylindrical support according to an embodiment of the present invention;

12 is a schematic structural diagram of an insulator according to an embodiment of the present invention;

13 is a sinusoidal voltage diagram of piezoelectric driving loading in Embodiment 2 of the present invention;

14 is a displacement diagram of the reference point of the piezoelectric simulation center in Embodiment 2 of the present invention;

Fig. 15 is the electromagnetic drive excitation current diagram of Embodiment 2 of the present invention;

16 is a displacement diagram of the reference point of the electromagnetic simulation center in Embodiment 2 of the present invention;

The parts in the figure are marked as follows:

Outer end cap 1, cylindrical shell 2, permanent magnet 3, cylindrical support 4, insulator 5, inner end cap 6, U-shaped spring 7, support frame 8, tri-laminate 9, metal substrate 10, piezoelectric ceramics Sheet 11.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments;

Example 1:

As shown in Figure 1-12, the piezoelectric-electromagnetic hybrid-driven dipole acoustic wave transducer includes two oppositely arranged outer end caps 1, and a cylindrical shell 2 arranged between the two outer end caps 1 and two permanent magnets 3, the two permanent magnets 3 are symmetrically arranged on the left and right positive sides of the cylindrical shell 2, the shape of the permanent magnet 3 is shown in Figure 7, and its cross section is arcuate, The planes of the two permanent magnets 3 are opposite and parallel to each other.

The cylindrical shell 2 includes a cylindrical support 4 whose ends are respectively connected with the two outer end caps 1. The cylindrical support 4 is made of a conductive material such as copper metal, and the cylindrical support 4 is fixed with a Two insulators 5; as shown in FIG. 12 , the insulators 5 are sector-shaped and made of carbon fiber. The two insulators 5 are disposed opposite to each other, and are disposed on the cylindrical shell 2 at a position away from the two permanent magnets 3 . As shown in FIG. 11 , the cylindrical bracket 4 includes two inner end caps 6 respectively connected with the two outer end caps 1 , and a U-shaped spring 7 is arranged between the inner end caps 6 and the outer end caps 1 . The shape of the U-shaped spring 7 is shown in FIG. 6 . When the cylindrical shell 2 vibrates, the U-shaped spring 7 can increase the vibration amplitude. The cylindrical bracket 4 also includes two support brackets 8 arranged between the two inner end caps 6 , the two support brackets 8 are arranged opposite to each other, and are respectively arranged on the cylindrical bracket 4 close to the two permanent magnets 3 . s position. The two insulators 5 and the two support frames 8 are interspersed and arranged at intervals. The two inner end caps 6 , the two support frames 8 and the two insulators 5 together form a fully enclosed cylindrical shell 2 . The sector-shaped insulator 5 can be directly fixed on the support frame 8 by screws, and the positive and negative electrodes of the excitation current are respectively connected to the two inner end caps 6, so that the current can pass through the cylindrical support 4 made of copper conductive material, The insulator 5 cannot pass through, so the current flows through the copper conductor directly opposite the permanent magnet 3, and the moving charged particles will be subjected to the Lorentz force in the magnetic field, so the cylindrical shell 2 will be deformed by the action of the Lorentz force.

The interior of the cylindrical shell 2 is provided with two sets of three laminations 9 connected between the two inner end caps 6 . The two piezoelectric ceramic sheets 11 on the side of the metal substrate 10 are connected to the two inner end caps 6 respectively, and the positive and negative electrodes of the excitation voltage are respectively connected to the metal substrate 10 and the piezoelectric ceramic sheet 11 .

The driving principle of the piezoelectric-electromagnetic hybrid driving dipole acoustic wave transducer of the present invention is as follows:

Piezoelectric drive principle: The three-layer laminate consists of two piezoelectric ceramic sheets and a metal substrate, the metal substrate is connected to the negative electrode of the excitation voltage, and the two piezoelectric ceramic sheets are connected to the positive electrode of the excitation voltage. According to the piezoelectric inverse effect of the piezoelectric device, one side of the piezoelectric ceramic sheet shrinks along the length direction, and the other side elongates along the length direction, so that the tri-laminate is bent. When the opposite voltage is applied to the tri-laminate, the tri-laminate will bend in the opposite direction. When a sinusoidal alternating voltage is applied to the tri-laminate, the tri-laminate will vibrate continuously due to the continuous change of the voltage, thereby driving the cylindrical The housing vibrates constantly. The cylindrical shell vibrates continuously, colliding with the medium in which it is placed to generate sound waves.

Electromagnetic drive principle:

Because of the existence of permanent magnets, a magnetic field along the X direction is generated between the two permanent magnets, as shown in Figure 1. Connect the positive and negative electrodes of the excitation current at both ends of the cylindrical shell. Since the carbon fiber is an insulator, the current will only flow on the copper conductor support frame directly opposite the permanent magnet. In the prior art, the entire cylindrical casing is directly set as a conductor, and the actual driving current is strengthened. The moving charged particles will be subject to the Lorentz force in the magnetic field, so the support frame of the cylindrical shell will be affected by the Lorentz force to drive the cylindrical shell to deform, and the moving charged particles will be subjected to the Lorentz force in the magnetic field. The force formula is as follows:

表示空间的电流密度，

表示磁通密度。当加载激励电流为交流电时，因为

方向不断地改变，而

是由永磁体产生，方向不会产生变化，所以

的方向会产生变化，圆柱形壳体形变方向变化，圆柱形壳体开始振动。in

represents the current density in space,

represents the magnetic flux density. When the loading excitation current is alternating current, because

direction is constantly changing, and

is generated by a permanent magnet, and the direction does not change, so

The direction of the cylindrical shell will change, the deformation direction of the cylindrical shell will change, and the cylindrical shell will start to vibrate.

On the basis of piezoelectric drive, electromagnetic drive is added to realize the hybrid drive of the two effects, and the vibration amplitude of the cylindrical shell is increased through the hybrid drive.

Increasing the length of the cylindrical shell can increase the vibration amplitude of the cylindrical shell under electromagnetic driving, but it will reduce the vibration amplitude of the cylindrical shell under piezoelectric driving. The vibration amplitude sum of the cylindrical shell under the two driving modes can be maximized by increasing the length of the cylindrical shell.

Example 2:

Firstly, the static simulation of the transducer structure is carried out to obtain its resonance frequencies of each order. Through observation, it is found that its vibration amplitude is the largest under the first-order resonance frequency, and the first-order resonance frequency is about 0.466Khz, which separates the piezoelectric drive and the electromagnetic drive. Simulation is carried out to observe the vibration of the cylindrical shell under the two driving modes.

Piezoelectric drive mode: load the two ends of the tri-laminate according to the measured first-order resonance frequency of the sinusoidal excitation voltage, and drive the tri-laminate to make the cylindrical shell vibrate.

Electromagnetic drive mode: load on the cylindrical shell according to the measured first-order resonance frequency as the frequency of the excitation current, drive the cylindrical shell, and make the cylindrical shell vibrate.

The improvement of the vibration amplitude of the piezoelectric-electromagnetic hybrid drive transducer compared with the piezoelectric transducer was observed by observing the displacement of the center point of the cylindrical shell.

The piezoelectric drive simulation loads the sinusoidal voltage as shown in Figure 13. The piezoelectric drive excitation voltage is a sinusoidal voltage with a peak value of 1000V and a frequency of 0.466Khz. The displacement of the center reference point (point A in Figure 1) is shown in Figure 14. Show:

It can be seen from the figure that the cylindrical shell of the transducer vibrates during the piezoelectric simulation. When a voltage is applied, the cylindrical shell will vibrate like a sine wave. After the applied voltage is over, the cylindrical shell will continue to vibrate due to inertia, but at a reduced frequency.

The electromagnetic simulation loads the excitation current shown in Figure 15. In Figure 15, the ordinate is the current I and the unit is A. The electromagnetic drive excitation current is the first derivative of the Gaussian function with a peak value of about 1000A and a frequency of 0.466Khz. The static magnetic field is 0.8T, and the displacement of the reference point (point A in Figure 1) is shown in Figure 16:

It can be seen from the figure that the cylindrical shell of the transducer vibrates during the electromagnetic simulation. When the current is loaded, the cylindrical shell will vibrate like a sine wave. After the applied current ends, due to inertia, the cylindrical shell will continue to vibrate, but the vibration amplitude is greatly reduced, and the vibration frequency is reduced.

From Figure 14 and Figure 16, it can be seen that the effect of the two driving methods in the time period of 0 to 3ms is highly consistent, and a good superposition effect can be achieved. Among them, the vibration amplitude is the largest near 2ms and 3ms. The sound wave generated by 3ms is stronger. Compared with the single piezoelectric driving method, the piezoelectric and electromagnetic hybrid driving method can increase the vibration amplitude of the cylindrical shell by about 10%.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention, and the purpose thereof is to enable those of ordinary skill in the art to understand the content of the present invention and implement them accordingly, and not to limit the protection scope of the present invention. All equivalent changes or modifications made according to the essence of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. Piezoelectric-electromagnetic hybrid drive type dipole acoustic wave transducer, is characterized in that: comprise two oppositely arranged outer end caps, be located in the cylindrical shell and two permanent magnets between the two outer end caps , the two permanent magnets are symmetrically arranged on both sides of the cylindrical shell; The cylindrical shell comprises a cylindrical support whose ends are respectively connected with two outer end caps, and two insulators fixed on the cylindrical support; the cylindrical support is made of conductive material; The two insulators are arranged opposite to each other, and are arranged on the cylindrical shell at a position away from the two permanent magnets; The cylindrical bracket includes two inner end caps respectively connected with the two outer end caps, and two supporting brackets arranged between the two inner end caps. The position on the bracket close to the two permanent magnets; The interior of the cylindrical shell is provided with two sets of three laminations connected between the two inner end caps; A U-shaped spring is arranged between the inner end cover and the outer end cover. 2 . The piezoelectric-electromagnetic hybrid-driven dipole acoustic wave transducer according to claim 1 , wherein the two insulators and the two support frames are interspersed and arranged at intervals. 3 . 3. The piezoelectric-electromagnetic hybrid-driven dipole acoustic wave transducer according to claim 1, wherein the two inner end caps, the two support frames and the two insulators are jointly enclosed into a fully enclosed Cylindrical shell. 4 . The piezoelectric-electromagnetic hybrid-driven dipole acoustic wave transducer according to claim 1 , wherein the two permanent magnets are oppositely arranged on the right and left sides of the cylindrical shell. 5 . 5 . The piezoelectric-electromagnetic hybrid-driven dipole acoustic wave transducer according to claim 1 , wherein the three-layer sheet comprises a metal substrate, and two are respectively arranged on both sides of the metal substrate. 6 . Piezoelectric ceramic sheet, two ends of the metal substrate are respectively connected with two inner end caps, and positive and negative electrodes of excitation voltage are respectively connected to the metal substrate and the piezoelectric ceramic sheet. 6 . The piezoelectric-electromagnetic hybrid-driven dipole acoustic wave transducer according to claim 1 , wherein the two inner end caps are respectively connected with positive and negative electrodes of excitation current. 7 . 7 . The piezoelectric-electromagnetic hybrid-driven dipole acoustic wave transducer according to claim 1 , wherein the permanent magnet is a prism, and the opposite faces of the two permanent magnets are parallel to each other, and the insulator is 7 . Scalloped, made of carbon fiber.

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