An underwater ultrasonic sensor

Abstract

The utility model discloses an underwater ultrasonic sensor, including matching layer, piezoelectric ceramic, metal shell, circuit board and signal transmission spare, one side of metal shell is equipped with the opening, piezoelectric ceramic sets up inside metal shell, and metal shell will piezoelectric ceramic's positive pole face completely surround, piezoelectric ceramic's negative pole face is directly opposite the opening, matching layer cover sets up on the opening of metal shell, and circuit board is connected with piezoelectric ceramic and signal transmission spare respectively. Circuit board is used at least to drive piezoelectric ceramic and vibrate along the radial or along the axial vibration. This underwater ultrasonic sensor will communication function and obstacle avoidance function integration, sets up metal shell and matching layer on the surface of piezoelectric ceramic respectively, and metal shell can pass through reflection and absorption to offset the interference of external electromagnetic wave signal to piezoelectric ceramic, and matching layer can pass through the degree of change of reducing acoustic impedance to improve the transmission efficiency of the ultrasonic wave produced by piezoelectric ceramic in its axial vibration direction.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, specifically to an underwater ultrasonic sensor. Background Technology

[0002] Underwater robots, also known as remotely operated vehicles (ROVs), are robots designed for extreme underwater operations. The underwater environment is harsh and dangerous, and human diving depth is limited, making underwater robots crucial tools for ocean exploration. Most existing underwater robots separate communication and obstacle avoidance, meaning they require multiple sensors, which is cumbersome. Furthermore, signals, especially communication signals, are easily interfered with when the robot is moving underwater.

[0003] Patent application CN120370322A discloses an underwater ultrasonic sensor and an underwater robot. Specifically, it discloses a circular piezoelectric ceramic, a sealed housing, and a cable. The circular piezoelectric ceramic is disposed inside the sealed housing, and the cable passes through the sealed housing and is electrically connected to the circular piezoelectric ceramic. The circular piezoelectric ceramic is used to emit ultrasonic signals in a preset direction and within a preset angle range upon receiving a control signal transmitted by the cable; and to output the ultrasonic echo signal through the cable upon receiving an ultrasonic echo signal in response to the ultrasonic signal. The preset direction extends outward along the radius of the circular piezoelectric ceramic. The preset angle range is a range of angles centered on the center of the circular piezoelectric ceramic.

[0004] The aforementioned patent can improve the detection range of underwater ultrasonic sensors, but it does not integrate communication and obstacle avoidance functions, nor can it prevent external electromagnetic signals from interfering with the ultrasonic sensors. Utility Model Content

[0005] In view of the problems existing in the prior art, the purpose of this utility model is to provide an underwater ultrasonic sensor that integrates communication and obstacle avoidance functions and prevents external electromagnetic signals from interfering with the ultrasonic sensor.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows:

[0007] An underwater ultrasonic sensor includes a matching layer, a piezoelectric ceramic, a metal housing, a circuit board, and a signal transmission device. One side of the metal housing has an opening. The piezoelectric ceramic is disposed inside the metal housing, and the metal housing completely surrounds the positive electrode surface of the piezoelectric ceramic. The negative electrode surface of the piezoelectric ceramic faces the opening. The matching layer covers the opening of the metal housing. The circuit board is connected to both the piezoelectric ceramic and the signal transmission device. The circuit board is used at least to drive the piezoelectric ceramic to vibrate radially or axially.

[0008] Furthermore, silicone is disposed between the metal housing and the piezoelectric ceramic.

[0009] Furthermore, the metal casing is made of copper.

[0010] Furthermore, the thickness of the matching layer is an odd multiple of a quarter wavelength.

[0011] Furthermore, the signal transmission component includes an enameled wire and a shielded wire. The positive end of the shielded wire passes through a through hole in the metal housing and is connected to the positive electrode surface of the piezoelectric ceramic. The circuit board is connected to the shielded wire via an IPEX2 terminal disposed on the negative end of the shielded wire. The negative electrode surface of the piezoelectric ceramic is connected to the circuit board via the enameled wire.

[0012] Furthermore, it also includes an adapter plate, through which the shielding layer of the shielded wire is soldered to the negative electrode of the piezoelectric ceramic using the enameled wire.

[0013] Furthermore, it also includes a housing, wherein the matching layer, the piezoelectric ceramic, the metal housing, the circuit board and the signal transmission component are respectively disposed inside the housing.

[0014] Furthermore, the interior of the outer shell is provided with a protruding structure, and the outer wall of the protruding structure, the inner wall of the bottom surface of the outer shell, and the inner wall of the side surface of the outer shell together form a placement space, and the matching layer is disposed in the placement space.

[0015] Furthermore, it also includes a sealant that fills the interior of the housing and encapsulates the mating layer, the piezoelectric ceramic, the metal housing, the circuit board, and the signal transmission element.

[0016] The beneficial effects of this utility model are as follows:

[0017] I. This utility model integrates communication and obstacle avoidance functions into one unit, thereby reducing its size.

[0018] II. This utility model has a metal shell and a matching layer respectively provided on the surface of the piezoelectric ceramic. The metal shell can cancel the interference of external electromagnetic wave signals on the piezoelectric ceramic by reflection and absorption. The matching layer can improve the transmission efficiency of the ultrasonic waves generated by the piezoelectric ceramic in its axial vibration direction (ultrasonic emission direction) by reducing the degree of change in acoustic impedance. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural schematic diagram of an embodiment of the present invention;

[0020] Figure 2 yes Figure 1 A schematic diagram of the decomposed structure;

[0021] Figure 3 yes Figure 1 A cross-sectional view;

[0022] Figure 4 yes Figure 1 A three-dimensional structural diagram of the inner shell.

[0023] Figure Labels

[0024] 100. Underwater ultrasonic sensor; 1. Matching layer; 2. Piezoelectric ceramic; 3. Metal housing; 4. Circuit board; 5. Signal transmission component; 6. Silicone; 7. Adapter board; 8. Raised structure; 81. Placement space; 9. Sealant; 10. Outer shell. Detailed Implementation

[0025] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "top surface", "bottom surface", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the position or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature. In this description of the utility model, "a number" means two or more, unless otherwise explicitly specified.

[0027] In this utility model, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0028] In this invention, "central axis" refers to a straight line that runs through the geometric center of an object and embodies its symmetry or main direction. "Radial" refers to the direction in which the object radiates horizontally outward from a point on the central axis or points horizontally outward towards a point on the central axis, i.e., the direction perpendicular to the central axis. "Axial" refers to the direction along the central axis.

[0029] In this embodiment, "interface" refers to the boundary line or contact surface between two different materials or media.

[0030] The utility model will be further described below with reference to the accompanying drawings and specific embodiments. The following description is merely exemplary and does not limit the scope of protection of the utility model.

[0031] Please refer to the details. Figures 1-4 This utility model discloses an underwater ultrasonic sensor 100, including a matching layer 1, a piezoelectric ceramic 2, a metal housing 3, a circuit board 4, and a signal transmission component 5. In this embodiment, one side of the metal housing 3 has an opening. The thickness of the piezoelectric ceramic 2 is less than or equal to the thickness of the metal housing 3. The piezoelectric ceramic 2 is disposed inside the metal housing 3, and the metal housing 2 completely surrounds the positive electrode surface of the piezoelectric ceramic 2. The negative electrode surface of the piezoelectric ceramic 2 faces the opening of the metal housing 3. The matching layer 1 is placed over the opening of the metal housing 3. Specifically, the top surface of the piezoelectric ceramic 2 is the positive electrode surface, and the bottom surface of the piezoelectric ceramic 2 is the negative electrode surface. During installation, the metal housing 3 completely covers the positive electrode surface and the side surface of the piezoelectric ceramic 2. The matching layer 1 seals the opening of the metal housing 3 and also covers the negative electrode surface of the piezoelectric ceramic 2. The circuit board 4 is connected to the piezoelectric ceramic 2 and the signal transmission component 5, and the circuit board 4 is used at least to drive the piezoelectric ceramic 2 to vibrate radially or axially. The piezoelectric ceramic 2 is used at least to transmit and receive ultrasonic signals, and the metal housing 3 is used at least to isolate the piezoelectric ceramic 2 from external signals (hereinafter referred to as electromagnetic waves).

[0032] In this embodiment, the piezoelectric ceramic 2 vibrates radially or is driven to vibrate axially, and the diameter of the piezoelectric ceramic 2 is greater than the thickness of the piezoelectric ceramic 2, so that the underwater ultrasonic sensor 100 can integrate communication and obstacle avoidance functions.

[0033] The radial vibration of the piezoelectric ceramic 2 is primarily used for communication. This is because the resonant frequency of the piezoelectric ceramic 2 during radial vibration is mainly determined by its diameter. The larger the diameter of the piezoelectric ceramic 2, the lower the vibration frequency. A lower vibration frequency results in less energy loss of the ultrasonic wave, meaning the ultrasonic wave can travel a greater distance. The ultrasonic waves generated in this vibration mode are oriented in all directions like a light bulb, meaning that the user, as the receiver, does not need to align the sensor with the underwater ultrasonic sensor 100, which is the transmitter, to achieve communication.

[0034] Specifically, a specific device sends a command, which is transmitted to the circuit board 4 via the signal transmission component 5. The circuit board 4 controls whether to apply voltage to the piezoelectric ceramic 2. When voltage is applied to the piezoelectric ceramic 2, it exhibits the inverse piezoelectric effect, that is, it generates low-frequency vibrations along the radial direction of the piezoelectric ceramic 2, such as 20kHz to 100kHz. This low-frequency vibration can propagate over a relatively long distance, at least 20 meters, and has low resolution, enabling communication through various underwater obstacles.

[0035] More specifically, when the piezoelectric ceramic 2 is used for communication, the negative electrode surface of the piezoelectric ceramic 2 can face either direction.

[0036] The axial vibration of the piezoelectric ceramic 2 is primarily used for obstacle avoidance (equivalent to ranging). This is because the resonant frequency of the piezoelectric ceramic 2 during axial vibration is mainly determined by its thickness. The thinner the piezoelectric ceramic 2, the higher the vibration frequency. A higher vibration frequency means a shorter wavelength of ultrasound waves. Shorter wavelength ultrasound waves are easier to distinguish smaller objects, and high-frequency ultrasound waves are easier to focus into a straight energy beam rather than spreading outwards. This enables directional detection and precise ranging. By measuring the time difference between sound wave emission and echo reception, the distance and outline of obstacles can be accurately calculated. In some preferred embodiments, the thickness of the piezoelectric ceramic 2 is half the wavelength.

[0037] Specifically, a specific device sends a command, which is transmitted via signal transmission element 5 to circuit board 4. Circuit board 4 controls whether to apply voltage to piezoelectric ceramic 2. When voltage is applied to piezoelectric ceramic 2, it exhibits the inverse piezoelectric effect, generating high-frequency vibrations, such as 1MHz or 2MHz. These high-frequency vibrations, upon contact with a medium, form ultrasonic waves. These ultrasonic waves propagate outward to a relatively short distance, approximately 0.5 to 10 meters, with high resolution, capable of detecting obstacles as small as a few centimeters. When these ultrasonic waves contact certain objects, they bounce off. These bounced ultrasonic waves strike the surface of piezoelectric ceramic 2, applying alternating pressure. This alternating pressure causes the piezoelectric ceramic 2 to produce minute mechanical vibrations, i.e., mechanical deformation. This mechanical deformation generates a high-frequency alternating voltage signal on the two electrodes of piezoelectric ceramic 2. This alternating voltage signal is processed by a built-in circuit (not shown in the figure) and converted into information such as distance, flow velocity, and image. This information is transmitted to a specific device to achieve advanced obstacle avoidance and navigation capabilities.

[0038] More specifically, when the piezoelectric ceramic 2 is used for obstacle avoidance (distance measurement), the negative electrode surface of the piezoelectric ceramic 2 must face the obstacle.

[0039] In this embodiment, a switching circuit (not shown in the figure) is provided on the circuit board 4. This switching circuit can determine whether the piezoelectric ceramic 2 vibrates radially or axially by changing the direction of the electric field. More specifically, in one vibration mode, the electric field passes perpendicularly through the thickness direction of the piezoelectric ceramic 2, and the piezoelectric ceramic 2 generates high-frequency vibration along the axial direction. In the other vibration mode, the switching circuit changes the direction of the electric field so that the electric field direction is parallel to the plane direction of the piezoelectric ceramic 2, and the piezoelectric ceramic 2 generates low-frequency vibration radially.

[0040] On one hand, the metal casing 3 can isolate the piezoelectric ceramic 2 from external signals. This is because: 1. Due to the large number of free electrons inside the metal, when external electromagnetic waves attempt to pass through the metal casing 3, these free electrons immediately move under the influence of the electric field, generating an induced electric field of equal magnitude but opposite direction to the external electric field. This ultimately cancels out the external electric field, achieving isolation. Essentially, the electromagnetic waves are canceled out by the reflected induced electric field. 2. Metal is not an ideal conductor and has a certain resistance. When electromagnetic waves, especially changing magnetic fields, enter the surface of the metal casing 3, eddy currents are induced inside the metal. These eddy currents dissipate the energy of the electromagnetic waves, converting it into heat. As the electromagnetic waves penetrate the metal, their energy is continuously attenuated, and their intensity drops sharply, essentially absorbing the electromagnetic waves. In summary, the metal casing 3 acts like a Faraday cage, canceling the interference of external electromagnetic wave signals on the piezoelectric ceramic 2 through reflection and absorption. This is particularly effective when the piezoelectric ceramic 2 vibrates radially for communication, especially in long-distance communication signal transmission, where the communication signal is unaffected by external electromagnetic wave signals.

[0041] On the other hand, the metal casing 3 can prevent the high voltage generated on the positive electrode surface of the piezoelectric ceramic 2 from affecting the signal of the circuit board 4 when the piezoelectric ceramic 2 vibrates.

[0042] Specifically, the metal housing 3 is a cylindrical shape with one open side, including a side and a bottom. In a preferred embodiment, the side and bottom are integrally formed. This is because, although electromagnetic waves are reflected and absorbed by the metal housing 3, they can easily pass through any gaps, thus interfering with the piezoelectric ceramic 2. The integral forming of the side and bottom ensures that the metal housing 3 has no gaps, thereby improving the working efficiency of the underwater ultrasonic sensor 100.

[0043] Please refer to Figure 3More specifically, in this embodiment, a silicone 6 is disposed between the metal shell 3 and the piezoelectric ceramic 2, and the shape of the silicone 6 matches the shape of the metal shell 3. The purpose of the silicone 6 is as follows: First, since the piezoelectric ceramic 2 is a hard but brittle material, if the piezoelectric ceramic 2 and the metal shell 3 are in direct rigid contact, the piezoelectric ceramic 2 is prone to breakage when a voltage is applied and it vibrates. Second, since whether the piezoelectric ceramic 2 is affected by electromagnetic interference depends on the degree of enclosure of the metal shell 3, and it is difficult to ensure that the metal shell 3 is perfectly flat at the microscopic level during the manufacturing process, the silicone 6, based on its fluidity, can fill these microscopic gaps, ensuring a stable mechanical coupling between the piezoelectric ceramic 2 and the metal shell 3 through the silicone 6. Even though the silicone 6 itself is not conductive, it makes the metal shell 3 a more complete shield to enclose the piezoelectric ceramic 2. Third, the silicone 6 has thermal conductivity, which can transfer the heat generated by the high-frequency vibration of the piezoelectric ceramic 2 to the metal shell 3, and then dissipate it outward from the metal shell 3, which helps to control the temperature of the piezoelectric ceramic 2.

[0044] In this embodiment, the metal shell 3 is made of copper. Its advantages are: 1. Copper has high electrical conductivity. When electromagnetic waves act on the copper metal shell 3, free electrons on the surface of the metal shell 3 move rapidly, generating an induced electric field opposite to the direction of the external electromagnetic field, thus reflecting away most of the electromagnetic energy and protecting the piezoelectric ceramic 2 from external electromagnetic interference. 2. Copper has high thermal conductivity, meaning it can quickly absorb the heat generated by the internal piezoelectric ceramic 2 under high-frequency vibration and evenly transfer it to the entire surface of the metal shell 3, ultimately dissipating it into the external environment, thereby improving the service life of the entire underwater ultrasonic sensor 100. 3. Since the underwater ultrasonic sensor 100 is used on the water surface or underwater, copper's excellent corrosion resistance can improve the service life of the metal shell 3 in this environment. Of course, in other embodiments, the metal shell 3 can also be made of aluminum, steel, or other metal materials; this is not a limitation.

[0045] In this embodiment, the matching layer 1 is provided because the piezoelectric ceramic 2 has a high acoustic impedance (i.e., the resistance of the medium to the propagation of sound waves), while water has a low acoustic impedance. When sound waves propagate from the high-impedance piezoelectric ceramic 2 to the low-impedance medium (water), a strong reflection occurs at the contact point, and the energy is bounced back into the piezoelectric ceramic 2. The matching layer 1 is designed with an acoustic impedance between that of the piezoelectric ceramic 2 and the medium to ensure that the change in acoustic impedance between the two contacts from the piezoelectric ceramic 2 to the matching layer 1 and then from the matching layer 1 to the medium is minimized. Therefore, the transmission efficiency of the ultrasonic waves generated by the piezoelectric ceramic 2 in its axial vibration direction can be improved, thereby maximizing the overall transmittance of the underwater ultrasonic sensor 100.

[0046] Specifically, in this embodiment, the thickness of the matching layer 1 is an odd multiple of a quarter wavelength. This is because when the ultrasonic wave enters the matching layer 1 from the piezoelectric ceramic 2, it generates a reflected wave R1 (not shown in the figure) towards the piezoelectric ceramic 2 at the first interface. As the ultrasonic wave continues to propagate through the matching layer 1, it reaches the second interface and generates a reflected wave R2 (not shown in the figure) towards the piezoelectric ceramic 2. The reason for designing the thickness of the matching layer 1 to be a quarter wavelength is that when the reflected wave R2 returns to the first interface, its propagation path is half a wavelength, and its phase is reversed by 180 degrees. That is, when the reflected wave R2 meets the reflected wave R1, their phases are opposite (the two reflected waves cancel each other out), ultimately increasing the transmittance of the ultrasonic energy.

[0047] More specifically, in one optional embodiment, the mating layer 1 is made by mixing epoxy resin and tungsten powder in a specific ratio. Of course, the mating layer 1 can also be made by mixing other materials, and this is not limited here.

[0048] Please refer to the details. Figures 3-4 The underwater ultrasonic sensor 100 also includes a housing 10, with a matching layer 1, piezoelectric ceramic 2, metal housing 3, circuit board 4, and signal transmission component 5 respectively disposed inside the housing 10. A protruding structure 8 is provided inside the housing 10. The outer wall of the protruding structure 8, the inner wall of the bottom surface of the housing 10, and the inner wall of the side surface of the housing 10 together form a placement space 81. The matching layer 1 is disposed in this placement space 81, and the thickness of the matching layer 1 is approximately the same as the height of the portion of the protruding structure 8 located on the inner wall of the bottom surface of the housing 10. This allows the matching layer 1, after being installed in the placement space 81, to form a plane with the top surface of the protruding structure 8, thereby providing continuous large-area contact for the piezoelectric ceramic 2. A larger contact area means greater friction between the piezoelectric ceramic 2 and the plane, making it less prone to slippage even when the underwater ultrasonic sensor 100 is subjected to external force and vibrates. Of course, in other embodiments, the thickness of the matching layer 1 can be greater or less than the height of the protruding structure 8; this is not limited here. Meanwhile, the protruding structure 8 on the inner wall of the side of the outer casing 10 is mainly used to limit the piezoelectric ceramic 2.

[0049] Please refer to the details. Figure 3The underwater ultrasonic sensor 100 also includes a sealant 9, which fills the interior of the housing 10 and encapsulates the matching layer 1, piezoelectric ceramic 2, metal housing 3, circuit board 4, and signal transmission component 5. The sealant 9 serves at least to isolate the interior space of the housing 10 from the external environment. Its functions are twofold: First, the sealant 9 forms a watertight barrier, isolating moisture and corrosive ions. This prevents water vapor (especially conductive seawater) from penetrating the interior of the metal housing 3, forming a conductive path between the two electrodes of the piezoelectric ceramic 2, or between the electrodes of the piezoelectric ceramic 2 and the metal housing 3, leading to high-voltage breakdown or signal short circuits and causing the underwater ultrasonic sensor 100 to completely fail. It also prevents water corrosion of the metal housing 3 and the electrodes of the piezoelectric ceramic 2. Second, during the assembly of the metal housing 3, piezoelectric ceramic 2, and matching layer 1, microscopic gaps inevitably exist. If these gaps are filled with air, the extremely low acoustic impedance of air causes near-complete reflection of sound waves at these air-filled locations, thus reducing sound energy transmission efficiency. As an acoustic coupling agent, sealant 9 can flow and fill these microscopic gaps, replacing the "air-metal" contact with a "sealant 9-metal" contact. Although the acoustic impedance of sealant 9 is not as good as that of metal matching, it is far superior to that of air, ensuring more efficient transmission of sound wave energy and forming a complete acoustic path.

[0050] Specifically, in this embodiment, the protruding structure 8 extends along the inner wall of the side of the outer shell 10 towards the opening of the outer shell 10 until it reaches the opening of the outer shell 10. When the metal shell 3 and the piezoelectric ceramic 2 are installed, due to the presence of the protruding structure 8 on the inner wall of the side of the outer shell 10, the metal shell 3 will be spaced at a predetermined distance from the inner wall of the side of the outer shell 10. The sealant 9 can fill the space between the metal shell 3 and the outer shell 10, preventing water, dust, mud or other contaminants from entering the interior of the outer shell 10. At the same time, it can also absorb the thermal stress generated by the expansion and contraction of the metal shell 3 and the piezoelectric ceramic 2 due to the different coefficients of thermal expansion, preventing the metal shell 3 and the piezoelectric ceramic 2 from cracking or detaching due to long-term stress fatigue.

[0051] In this embodiment, the signal transmission component 5 includes an enameled wire (not shown in the figure) and a shielding wire (not shown in the figure). The positive end of the shielding wire passes through a through hole (not shown in the figure) on the metal housing 3 and is connected to the positive electrode surface of the piezoelectric ceramic 2. The circuit board 4 is connected to the shielding wire through the IPEX2 terminal provided at the negative end of the shielding wire, and the negative electrode surface of the piezoelectric ceramic 2 is connected to the circuit board 4 through the enameled wire. Of course, in some other embodiments, the signal transmission component 5 can also be a wireless communication device such as Bluetooth, which is not limited here.

[0052] In this embodiment, the underwater ultrasonic sensor 100 also includes an adapter plate 7, through which the shielding layer of the shielding wire is soldered to the negative electrode of the piezoelectric ceramic 2 using enameled wire.

[0053] The working principle of this utility model is described below to facilitate a better understanding of it:

[0054] A specific device sends commands to circuit board 4, which controls whether voltage is applied to the piezoelectric ceramic 2 and the direction of the electric field when the voltage is applied. When the piezoelectric ceramic 2 vibrates radially, it generates low-frequency ultrasonic waves. The farther these low-frequency ultrasonic waves can travel, the less the user, as the receiver, needs to align with the underwater ultrasonic sensor 100, as the transmitter, to achieve communication. When the piezoelectric ceramic 2 vibrates axially, it generates high-frequency, short-wavelength ultrasonic waves. Short-wavelength ultrasonic waves are easier to distinguish smaller objects, while high-frequency ultrasonic waves are easier to focus into a straight energy beam rather than spreading outwards. This enables directional detection and precise distance measurement. By measuring the time difference between sound wave emission and echo reception, the distance and outline of obstacles can be accurately calculated, thus achieving obstacle avoidance.

[0055] In summary, this underwater ultrasonic sensor 100 integrates communication and obstacle avoidance functions. A metal housing 3 and a matching layer 1 are respectively disposed on the surface of the piezoelectric ceramic 2. The metal housing 3 can counteract the interference of external electromagnetic signals on the piezoelectric ceramic 2 through reflection and absorption, while the matching layer 1 can improve the transmission efficiency of the ultrasonic waves generated by the piezoelectric ceramic 2 in its axial vibration direction (ultrasonic emission direction) by reducing the degree of change in acoustic impedance. Ultimately, with the cooperation of the metal housing 3 and the matching layer 1, even long-distance communication will not experience significant signal interference, and the detection efficiency of obstacles will be higher.

Claims

1. An underwater ultrasonic sensor, characterized in that, include: The device comprises a matching layer, a piezoelectric ceramic, a metal housing, a circuit board, and a signal transmission device. One side of the metal housing has an opening. The piezoelectric ceramic is disposed inside the metal housing, and the metal housing completely surrounds the positive electrode surface of the piezoelectric ceramic. The negative electrode surface of the piezoelectric ceramic faces the opening. The matching layer covers the opening of the metal housing. The circuit board is connected to the piezoelectric ceramic and the signal transmission device, respectively. The circuit board is used to drive the piezoelectric ceramic to vibrate radially or to drive the piezoelectric ceramic to vibrate axially.

2. The underwater ultrasonic sensor according to claim 1, characterized in that: The metal casing is made of copper.

3. The underwater ultrasonic sensor according to claim 1, characterized in that: Silicone is disposed between the metal casing and the piezoelectric ceramic.

4. The underwater ultrasonic sensor according to claim 1, characterized in that: The thickness of the matching layer is an odd multiple of a quarter wavelength.

5. The underwater ultrasonic sensor according to claim 1, characterized in that: The signal transmission component includes an enameled wire and a shielded wire. The positive end of the shielded wire passes through a through hole in the metal housing and is connected to the positive electrode surface of the piezoelectric ceramic. The circuit board is connected to the shielded wire via an IPEX2 terminal located on the negative end of the shielded wire. The negative electrode surface of the piezoelectric ceramic is connected to the circuit board via the enameled wire.

6. The underwater ultrasonic sensor according to claim 5, characterized in that: It also includes an adapter plate, through which the shielding layer of the shielded wire is soldered to the negative electrode of the piezoelectric ceramic using the enameled wire.

7. The underwater ultrasonic sensor according to claim 1, characterized in that: It also includes a housing, and the matching layer, the piezoelectric ceramic, the metal housing, the circuit board and the signal transmission component are respectively disposed inside the housing.

8. The underwater ultrasonic sensor according to claim 7, characterized in that: The interior of the outer shell is provided with a protruding structure. The outer wall of the protruding structure, the inner wall of the bottom surface of the outer shell, and the inner wall of the side surface of the outer shell together form a placement space, and the matching layer is disposed in the placement space.

9. The underwater ultrasonic sensor according to claim 8, characterized in that: It also includes a sealant that fills the interior of the housing and encapsulates the mating layer, the piezoelectric ceramic, the metal housing, the circuit board, and the signal transmission element.

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