Ultrasonic sensors, electronics and wind measurement systems

Abstract

The present disclosure relates to an ultrasonic sensor, an electronic device and a wind measurement system, wherein the ultrasonic sensor comprises: a housing, comprising a first accommodating cavity with an opening at one end; an elastic sleeve, wherein the outer wall shape of the elastic sleeve is matched and fixed to the inner wall of the housing; a piezoelectric crystal, comprising a pole and a lead connecting the pole, wherein the piezoelectric crystal is fixed in the elastic sleeve; and a matching layer, which is sealed and installed at the open end of the first accommodating cavity. When in use, by fixing the piezoelectric crystal in the elastic sleeve and the elastic sleeve on the inner wall of the housing, on the one hand, the problem that the piezoelectric crystal is not easy to stick to the housing can be solved; on the other hand, the problem that the housing and the piezoelectric crystal have different expansion coefficients, which may cause the piezoelectric crystal to separate from the housing under the action of internal stress when used in an environment with a large temperature difference, can be avoided.

Description

Technical Field

[0001] The present disclosure relates to the field of sensors, and in particular, to an ultrasonic sensor, an electronic device, and a wind measurement system. Background Art

[0002] Commonly used ultrasonic sensors are assembled from a shell, a piezoelectric crystal, a sealing layer and leads. They can both transmit and receive ultrasonic waves. The reliability and durability of ultrasonic sensors mainly depend on the internal structure and the performance of the piezoelectric crystal.

[0003] The existing ultrasonic sensor assembly process is to stick the piezoelectric crystal into the shell. The shell used is metal or plastic. The piezoelectric crystal is not easy to stick to the plastic or metal. In addition, the plastic or metal has different expansion coefficients from the piezoelectric crystal. When used in an environment with a large temperature difference, the piezoelectric crystal will separate from the shell under the action of internal stress, resulting in a short product life cycle. The internal structure of this sensor directly affects the stability and reliability of ultrasonic measurement. Summary of the invention

[0004] The purpose of the present disclosure is to provide an ultrasonic sensor, an electronic device, and a wind measurement system to at least partially solve the problems existing in the related art.

[0005] In order to achieve the above-mentioned purpose, the present disclosure provides an ultrasonic sensor, comprising: a shell, comprising a first accommodating cavity with an opening at one end; an elastic sleeve, the outer wall of which is shaped to match and fit the inner wall of the first accommodating cavity; a piezoelectric crystal, comprising an electrode and a lead connecting the electrode, the piezoelectric crystal being fixed in the elastic sleeve; and a matching layer, which is sealed and installed on the open end of the first accommodating cavity.

[0006] Optionally, the elastic sleeve is configured to be tensioned by being pushed outward by the piezoelectric crystal.

[0007] Optionally, an adhesive is coated between the elastic sleeve and the shell.

[0008] Optionally, the matching layer is fixed to an end face of the piezoelectric crystal close to the open end.

[0009] Optionally, the ultrasonic sensor also includes a damping portion arranged in the elastic sleeve; the piezoelectric crystal is fixed in a position close to the open end of the elastic sleeve, and the damping portion is arranged in a position away from the open end of the elastic sleeve; wherein the two ends of the damping portion are respectively fixed on the piezoelectric crystal and on the end face of the closed end of the first accommodating cavity opposite to the open end.

[0010] Optionally, the damping portion is an elastic block structure and is fixed in the elastic sleeve in a shape-fitting manner.

[0011] Optionally, two ends of the damping portion elastically abut against the end surfaces of the piezoelectric crystal and the closed end.

[0012] Optionally, the material of the damping part is polyethylene foam.

[0013] Optionally, a through hole for the lead to extend out is formed in the cavity wall of the first accommodating cavity, and the housing further comprises a second accommodating cavity with one end connected to the through hole and the other end open, and the lead extends out of the through hole and in the second accommodating cavity.

[0014] Optionally, shielding layers are provided at all positions of the cavity walls of the first accommodating cavity and the second accommodating cavity.

[0015] Optionally, the open end of the second accommodating cavity is filled with a blocking block, and the blocking block has a wire hole for the lead wire to pass through.

[0016] 0 Optionally, the material of the shell is carbon fiber.

[0017] Optionally, the material of the matching layer is vulcanized rubber mixed with titanium dioxide.

[0018] Optionally, the cross-sections of the piezoelectric crystal and the matching layer are circular, the frequency of the piezoelectric crystal is 180 kHz-210 kHz, and the thickness of the matching layer is 0.95 mm-1.1 mm.

[0019] According to a second aspect of the present disclosure, there is provided an electronic device comprising the above-mentioned ultrasonic sensor 5 .

[0020] Optionally, there are multiple ultrasonic sensors.

[0021] Optionally, the electronic device is an ultrasonic anemometer.

[0022] According to a third aspect of the present disclosure, a wind measurement system is provided, comprising the above-mentioned electronic device.

[0023] Through the above technical solution, when in use, by fixing the piezoelectric crystal in the elastic sleeve and the elastic sleeve on the inner wall of the shell, on the one hand, the problem that the piezoelectric crystal is not easy to stick to the shell can be solved; on the other hand, it can avoid the problem that the shell and the piezoelectric crystal have different expansion coefficients, which will cause the piezoelectric crystal to separate from the shell due to internal stress when used in an environment with a large temperature difference.

[0024] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0026] Figure 1 is an exploded diagram of an ultrasonic sensor exemplarily shown according to the present disclosure;

[0027] Figure 2 is a cross-sectional view of an ultrasonic sensor exemplarily shown according to the present disclosure.

[0028] Figure 3 is a cross-sectional view of a housing exemplarily shown according to the present disclosure;

[0029] Figure 4 It is a schematic diagram of a combination of a piezoelectric crystal, a damping part and an elastic sleeve according to an exemplary embodiment of the present disclosure.

[0030] Description of Reference Numerals

[0031] 10-shell; 11-first accommodating chamber; 111-opening end; 12-second accommodating chamber; 13-through hole; 20-elastic sleeve; 30-piezoelectric crystal; 31-lead; 32-pole; 40-matching layer; 50-damping part; 60-blocking block; 61-wire hole; 70-shielding layer. DETAILED DESCRIPTION

[0032] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0033] In the present disclosure, unless otherwise stated, directional words such as "inside" and "outside" are used based on the structure of the relevant components themselves. For example, the "inner wall" of the shell refers to the wall surface forming the accommodation space inside the shell; the "inner diameter" of the elastic sleeve refers to the diameter of the accommodation space inside the elastic sleeve.

[0034] In addition, in the present disclosure, the terms "first", "second", etc. are used to distinguish one element from another element, and have no order or importance. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0035] Reference Figure 1-Figure 4The present disclosure provides an ultrasonic sensor, which includes a shell 10, an elastic sleeve 20, and a piezoelectric crystal 30 fixed in the elastic sleeve 20, wherein the shell 10 includes a first accommodating cavity 11 with an opening at one end, the outer wall of the elastic sleeve 20 is matched in shape and fixed to the inner wall of the first accommodating cavity 11, and the piezoelectric crystal 30 includes a pole 32 and a lead 31 connecting the pole. In addition, the ultrasonic sensor may also include a matching layer 40 sealed and installed at the open end 111 of the first accommodating cavity 11, the matching layer 40 has a coupled sound-transmitting effect to be described below, and can be used to seal the shell 10. Here, the pole 32 of the piezoelectric crystal 30 includes a positive pole and a negative pole, and the number of the lead 31 is two and they are respectively connected to the positive pole and the negative pole.

[0036] Piezoelectric crystal 30 refers to a non-centrosymmetric crystal. Under the action of mechanical force, it deforms, causing charged particles to undergo relative displacement, thereby generating positive and negative bound charges on the surface of the crystal. Such a crystal is called a piezoelectric crystal. Since the structure and working principle of the piezoelectric crystal 30 are well known to those skilled in the art, they will not be introduced in detail here.

[0037] The present disclosure does not limit the material of the elastic sleeve 20. For example, in the embodiment of the present disclosure, the elastic sleeve 20 may be a rubber tube. In addition, in some other embodiments, the elastic sleeve 20 may also be a nylon tube.

[0038] By using the above technical solution, when in use, by fixing the piezoelectric crystal 30 in the elastic sleeve 20 and the elastic sleeve 20 on the inner wall of the housing 10, on the one hand, the problem of the piezoelectric crystal 30 and the housing 10 not being easy to stick together can be solved; on the other hand, the problem of the housing 10 and the piezoelectric crystal 30 having different expansion coefficients, which may cause the piezoelectric crystal 30 to separate from the housing 10 under the action of internal stress when used in an environment with a large temperature difference, can be avoided. In addition, by designing the elastic sleeve 20 to abut between the piezoelectric crystal 30 and the housing 10, it can also play a role in buffering and shock absorption.

[0039] In order to fix the piezoelectric crystal 30 in the elastic sleeve 20, in the embodiment of the present disclosure, the elastic sleeve 20 can be configured to be tensioned by being pushed outward by the piezoelectric crystal 30. That is, in the natural state (the two are not assembled), the inner diameter of the elastic sleeve 20 is smaller than the outer diameter of the piezoelectric crystal 30. During assembly, the inner diameter of the elastic sleeve 20 is expanded by external force, and the piezoelectric crystal 30 is placed in the elastic sleeve 20, and then the external force is removed to make the elastic sleeve 20 recover its deformation until it tightly wraps the piezoelectric crystal 30 (tension), so as to fix the piezoelectric crystal 30 in the elastic sleeve 20. In addition, according to some other embodiments, an adhesive can be coated between the elastic sleeve 20 and the piezoelectric crystal 30 so that the piezoelectric crystal 30 can be fixed in the elastic sleeve 20.

[0040] In the embodiment of the present disclosure, in order to fix the elastic sleeve 20 to the inner wall of the housing 10 in a shape-matched manner, in the embodiment of the present disclosure, an adhesive may be applied between the elastic sleeve 20 and the housing 10 so that the elastic sleeve 20 can be bonded to the inner wall of the housing 10. The present disclosure does not limit the specific type of the adhesive. For example, in some embodiments, the adhesive may be an epoxy resin glue. In addition, in some other embodiments, the adhesive may be a polymer glue, an unsaturated resin glue, etc.

[0041] Reference Figure 2 In the embodiment of the present disclosure, the matching layer 40 can be fixed on the end surface of the piezoelectric crystal 30 near the open end 111. Specifically, since the matching layer 40 has a certain adhesiveness, it can be directly bonded to the piezoelectric crystal 30. Since the volume of the matching layer 40 will shrink after solidification, the diameter of the solid matching layer 40 can be slightly larger than the diameter of the piezoelectric crystal 30. The specific size difference between the two can be adaptively designed according to actual conditions. The present disclosure is not limited to this, as long as the matching layer 40 can just seal the first accommodation cavity 11 after solidification.

[0042] Reference Figure 1-Figure 2 , Figure 4 In the embodiment of the present disclosure, the ultrasonic sensor may further include a damping portion 50 disposed in the elastic sleeve 20, wherein the piezoelectric crystal 30 may be fixed at a position close to the open end 111 in the elastic sleeve 20, and the damping portion 50 may be disposed at a position away from the open end 111 in the elastic sleeve 20, wherein the two ends of the damping portion 50 are respectively fixed on the piezoelectric crystal 30 and on the end surface of the closed end of the first accommodating cavity 11 opposite to the open end 111. With such a design, one end of the piezoelectric crystal 30 abuts against the damping portion 50, and the damping portion 50 may damp the piezoelectric crystal 30 so that the piezoelectric crystal 30 may stop vibrating quickly, thereby reducing the residual vibration of the piezoelectric crystal 30 and ensuring the normal operation of the ultrasonic sensor.

[0043] The specific configuration of the damping part 50 is not limited in the embodiment of the present disclosure. For example, the damping part 50 can be a block structure with elasticity and fixed in the elastic sleeve 20 in a shape-matching manner. The elastic damping part 50 can quickly eliminate the residual vibration when the piezoelectric crystal 30 vibrates, and the damping part 50 is set to be elastic so that it can play a buffering and protective role when the piezoelectric crystal 30 is impacted by external forces. Compared with the damping part 50 formed by the combination of a rigid block structure and a spring, the embodiment using only an elastic block structure has the advantages of less difficulty in assembly process and low production cost.

[0044] In order to further reduce the residual vibration of the piezoelectric crystal 30, in the embodiment of the present disclosure, the two ends of the damping part 50 can elastically press against the end surface of the piezoelectric crystal 30 and the closed end. In this case, the damping part 50 can always form elastic pressure on the piezoelectric crystal 30, and when the piezoelectric crystal 30 vibrates, the residual vibration can be quickly eliminated until the vibration stops, thereby improving the stability of the sensor.

[0045] In order to enable the damping part 50 to form an elastic support for the piezoelectric crystal 30, during the production process, when the damping part 50 and the piezoelectric crystal 30 are assembled, the sum of the thickness of the piezoelectric crystal 30 and the damping part 50 can be configured to be greater than the height of the shell 10 (under the natural state). During assembly, the damping part 50 is mechanically compressed so that the sum of the thickness of the damping part 50 and the piezoelectric crystal 30 is equal to the height of the shell 10 (at this time, the damping part 50 is elastic). The damping part 50 has the characteristics of elasticity and non-deformation, so it plays a dual role of elastic support and damping, which can reduce the residual vibration of the piezoelectric crystal 30 to a greater extent.

[0046] Further, in the embodiments of the present disclosure, the material of the damping part 50 can be polyethylene foam, that is, pearl cotton, which is composed of countless independent bubbles produced by physical foaming of low-density polyethylene grease. When ultrasonic waves are transmitted through polyethylene foam, the sound waves pass through the small holes inside the pearl cotton and rub against the hole walls to convert into heat energy, which has a suppressive effect on residual vibration. In addition to the damping effect of sound absorption and shockproof, polyethylene foam has many advantages such as waterproof and moisture-proof, corrosion resistance, strong toughness and no deformation, and also has good chemical resistance. Polyethylene foam is selected as the damping part 50. Due to the special structure inside the polyethylene foam, the ultrasonic sensor can also transmit more energy and receive more efficiently. In addition, in some other embodiments, according to the requirements of the accuracy of the sensor, the material of the damping part 50 can also be sound-absorbing cotton, such as felt material, sponge, etc.

[0047] Reference Figure 3 In order to allow the lead wire 31 welded on the pole 32 to pass through the first accommodating cavity 11 and extend along the corresponding channel, in the embodiment of the present disclosure, the cavity wall of the first accommodating cavity 11 may be provided with a through hole 13 for the lead wire 31 to extend out, and the housing 10 further includes a second accommodating cavity 12 with one end connected to the through hole 13 and the other end open, and the lead wire 31 may extend out of the through hole 13 and extend in the second accommodating cavity 12. When in use, in addition to providing a routing channel for the lead wire 31 as described above, the second accommodating cavity 12 may also play a supporting and mounting role.

[0048] Reference Figure 3In the embodiment of the present disclosure, the through hole 13 can be opened at a position of the cavity wall of the first accommodating cavity 11 away from the open end 111. In addition, in some other embodiments, the through hole 13 can be opened at a middle position of the cavity wall of the first accommodating cavity 11 according to actual use requirements, and the present disclosure does not limit the opening position of the through hole 13.

[0049] Reference Figure 3 In order to prevent external electromagnetic signals from entering the circuit and thus affecting the normal operation of the ultrasonic sensor, in the embodiment of the present disclosure, shielding layers 70 can be provided at all positions of the cavity walls of the first accommodating cavity 11 and the second accommodating cavity 12. Such a design can ensure that the shielding layer 70 is formed on the periphery of all parts of the piezoelectric crystal 30 and the lead 31, and the lead 31 directly enters another metal accommodating cavity after extending from the second accommodating cavity 12, which still has the function of shielding external interference signals, thereby effectively preventing external interference signals from entering the circuit.

[0050] The present disclosure does not specifically limit the shielding layer 70, as long as it can prevent external interference signals from entering the circuit and affecting the normal use of the ultrasonic sensor. For example, in the embodiment of the present disclosure, the shielding layer 70 can be a copper foil layer embedded in the cavity wall of the first accommodating cavity 11 and the second accommodating cavity 12. In addition, in some other embodiments, the shielding layer 70 can be an aluminum foil layer embedded in the cavity wall of the first accommodating cavity 11 and the second accommodating cavity 12.

[0051] In order to prevent foreign matter, moisture, etc. from entering the housing 10 and thus reducing the service life of the ultrasonic sensor, all openings of the housing 10 need to be sealed. Figure 1-Figure 2 In the embodiment of the present disclosure, the open end of the second accommodating cavity 12 is filled with a blocking block 60, and the blocking block 60 has a wire hole 61 for the lead wire 31 to pass through. The blocking block 60 can seal the opening of the second accommodating cavity 12, thereby preventing impurities, moisture, etc. from entering the interior of the housing 10, so as to improve the service life of the ultrasonic sensor.

[0052] The present disclosure does not limit the formation method of the blocking block 60. For example, in the embodiments of the present disclosure, the blocking block 60 can be an epoxy resin block. When in use, it is only necessary to inject epoxy resin into the open end of the second accommodating cavity 12 and block the opening of the second accommodating cavity 12 and wait for it to solidify. In this case, the epoxy resin wraps the lead 31, that is, the lead 31 passes through the wire hole 61 on the epoxy resin block. In addition, in some other embodiments, the blocking block 60 can be a rubber block that matches the opening shape of the second accommodating cavity 12. The rubber block is provided with a wire hole 61 for the lead 31 to pass through. When in use, the lead 31 is first extended from the wire hole 61, and then the rubber block is inserted into the opening of the second accommodating cavity 12 for blocking. At this time, the size of the rubber block can be slightly larger than the size of the opening, that is, the rubber block is fixed to the open end of the second accommodating cavity 12 by interference fit. In addition, the rubber block can also be bonded to the opening of the second accommodating cavity 12 by adhesive.

[0053] In order to improve the corrosion resistance, aging resistance, fatigue resistance and other aspects of the ultrasonic sensor, according to some embodiments, the material of the ultrasonic sensor housing 10 may be carbon fiber. Carbon fiber has the characteristics of high strength, high temperature resistance, corrosion resistance, aging resistance, and fatigue resistance, and such a design can extend the service life of the ultrasonic sensor. In addition, in some other embodiments, the housing 10 may be specially treated, such as forming an oxide film on its outer layer, or the housing 10 may be made of a composite material with high corrosion resistance, aging resistance, and fatigue resistance.

[0054] In the related art, the common material of the matching layer 40 is resin glue. After such products are used for a long time in an environment with a large temperature difference, the bonding interface between the piezoelectric crystal 30 and the matching layer 40 will peel off due to the poor toughness and brittle cracking of the solidified material of the colloid itself, thereby affecting the normal operation of the ultrasonic sensor.

[0055] In view of the above technical problems, in the embodiment of the present disclosure, the material of the matching layer 40 can be vulcanized rubber mixed with titanium dioxide. Vulcanized rubber can be used for a long time in the temperature range of -60 to 200 ° C, has excellent chemical non-deformation function, is waterproof and moisture-proof, resistant to ozone and ultraviolet rays, resistant to weather aging, corrosion-resistant, insulating, shock-proof, and has excellent adhesion to a variety of metal and non-metallic materials. The most important characteristic is that it can maintain a large elasticity after long-term use, unlike the matching layer 40 of resin glue, which has the defects of poor toughness and easy brittle cracking, resulting in peeling of the bonding interface between the piezoelectric crystal 30 and the matching layer 40. In addition, the specific vulcanized rubber used in the present invention is transparent, and titanium dioxide is added and mixed in a certain proportion. In addition to achieving the whitening and covering effect, titanium dioxide can also prevent the rubber from yellowing and cracking during the vulcanization process, and enhance the viscosity of the rubber, increase the degree of adhesion with the shell 10, and the matching layer 40 mixed with titanium dioxide enhances the heat resistance, aging resistance, ultraviolet resistance and other characteristics.

[0056] In order to ensure the sealing of the matching layer 40 to the open end 111 of the first accommodating cavity 11 and to meet the coupled sound transmission effect of the matching layer 40, in the embodiment of the present disclosure, the cross-sections of the piezoelectric crystal 30 and the matching layer 40 can be circular, the frequency of the piezoelectric crystal 30 can be 180kHz-210kHz, and the thickness of the matching layer 40 can be 0.95mm-1.1mm.

[0057] Specifically, according to the common knowledge in the art, when the thickness of the matching layer 40 is equal to one-fourth of the wavelength of the ultrasonic wave transmitted in the matching layer 40 material, the attenuation of the acoustic wave energy will be reduced, that is, the optimal acoustically transparent thickness of the matching layer 40 is t=λ / 4, where λ is the wavelength, and λ=v / f, where v is the speed and f is the frequency. In the matching layer 40 of the vulcanized silicone rubber (mixed with titanium dioxide) disclosed in the present invention, the speed of sound is 800 m / s, so when the frequency of the piezoelectric crystal 30 is 180 kHz, the optimal acoustically transparent thickness t of the matching layer 40 is 1.1 mm after being substituted into the above formula; when the frequency of the piezoelectric crystal 30 is 210 kHz, the optimal acoustically transparent thickness t of the matching layer 40 is 0.95 mm after being substituted into the above formula.

[0058] It should be noted that the optimal sound-transmissive thickness of the matching layer 40 is based on the actual propagation speed of sound in the matching layer 40 and the frequency of the piezoelectric crystal 30, and is not limited to the above data range, which is only an exemplary description. The specific value needs to be designed according to the material of the actual matching layer 40 and the frequency adaptability of the piezoelectric crystal 30.

[0059] According to a second aspect of the present disclosure, an electronic device is provided, comprising the ultrasonic sensor described above. Since the electronic device has all the beneficial effects of the ultrasonic sensor described above, they are not described in detail here.

[0060] Furthermore, in the embodiment of the present disclosure, the number of ultrasonic sensors can be multiple. The size and mass of the damping part 50 of each ultrasonic sensor can be the same. When in use, one of the two ultrasonic sensors that cooperate with each other is used to transmit signals, and the other is used to receive signals. In order to ensure the coordinated use of the two ultrasonic sensors, it is necessary to ensure that the resolution and sensitivity of the two sensors are the same.

[0061] The sensitivity of the piezoelectric crystal 30 is similar, and the mechanical Q value of the piezoelectric crystal 30 directly affects the resolution and sensitivity of the sensor. 5 The traditional packaging method is to inject potting glue into the housing 10. This method is difficult to ensure the quantitative injection of glue.

[0062] This will result in different Q values ​​of the piezoelectric crystal 30, which will lead to large differences in the resolution and sensitivity of the ultrasonic sensor, resulting in poor product consistency. The present application configures the damping parts 50 of the two ultrasonic sensors to be the same in size and mass, thereby ensuring the mechanical Q value of the piezoelectric crystal 30.

[0063] Consistency, thereby indirectly ensuring the consistency of the two ultrasonic sensors that cooperate with each other (eliminating the 0 process of glue filling).

[0064] According to some embodiments, the electronic device mentioned above may be an ultrasonic anemometer.

[0065] According to a third aspect of the present disclosure, a wind measurement system is provided, comprising the above electronic device, such as an ultrasonic anemometer. Since the wind measurement system has all the beneficial effects of the above electronic device, they will not be described in detail here.

[0066] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0067] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0068] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. An ultrasonic sensor, characterized in that: include: The housing (10) comprises a first accommodating cavity (11) with an opening at one end; An elastic sleeve (20), the outer wall of the elastic sleeve (20) having a shape matching that of the inner wall of the first accommodating cavity (11); A piezoelectric crystal (30) comprising a pole (32) and a lead wire (31) connected to the pole, the piezoelectric crystal (30) being fixed in the elastic sleeve (20), the inner diameter of the elastic sleeve (20) being smaller than the outer diameter of the piezoelectric crystal (30), so that the elastic sleeve (20) is pressed against the piezoelectric crystal (30) and thus tensioned; and The matching layer (40) is installed in a closed manner at the opening end (111) of the first accommodating cavity (11).

2. The ultrasonic sensor according to claim 1, characterized in that: An adhesive is coated between the elastic sleeve (20) and the shell (10).

3. The ultrasonic sensor according to claim 1, characterized in that: The matching layer (40) is fixed on the end surface of the piezoelectric crystal (30) close to the opening end (111).

4. The ultrasonic sensor according to claim 1, characterized in that: The ultrasonic sensor further comprises a damping portion (50) arranged in the elastic sleeve (20); The piezoelectric crystal (30) is fixed at a position in the elastic sleeve (20) close to the opening end (111), and the damping portion (50) is arranged at a position in the elastic sleeve (20) away from the opening end (111); Wherein, two ends of the damping part (50) are respectively fixed on the piezoelectric crystal (30) and on the end surface of the closed end of the first accommodating cavity (11) opposite to the open end (111).

5. The ultrasonic sensor according to claim 4, characterized in that: The damping portion (50) is an elastic block structure and is fixed in the elastic sleeve (20) in a shape-fitting manner.

6. The ultrasonic sensor according to claim 5, characterized in that: Both ends of the damping portion (50) elastically abut against the piezoelectric crystal (30) and the end surface of the closed end.

7. The ultrasonic sensor according to claim 5, characterized in that: The material of the damping part (50) is polyethylene foam.

8. The ultrasonic sensor according to claim 1, characterized in that: The cavity wall of the first accommodating cavity (11) is provided with a through hole (13) for the lead wire (31) to extend out, and the housing (10) further comprises a second accommodating cavity (12) having one end connected to the through hole (13) and the other end open, and the lead wire (31) extends out of the through hole (13) and extends in the second accommodating cavity (12).

9. The ultrasonic sensor according to claim 8, characterized in that: The cavity walls of the first accommodating cavity (11) and the second accommodating cavity (12) are respectively provided with shielding layers (70).

10. The ultrasonic sensor according to claim 8, characterized in that: The open end of the second accommodating cavity (12) is filled with a blocking block (60), and the blocking block (60) has a wire hole (61) for the lead wire (31) to pass through.

11. The ultrasonic sensor according to claim 1, characterized in that: The material of the shell (10) is carbon fiber.

12. The ultrasonic sensor according to claim 1, characterized in that: The material of the matching layer (40) is vulcanized rubber mixed with titanium dioxide.

13. The ultrasonic sensor according to claim 12, characterized in that: The cross-sections of the piezoelectric crystal (30) and the matching layer (40) are circular, the frequency of the piezoelectric crystal (30) is 180 kHz-210 kHz, and the thickness of the matching layer (40) is 0.95 mm-1.1 mm.

14. An electronic device, characterized in that: The ultrasonic sensor comprises the ultrasonic sensor as claimed in any one of claims 1 to 13.

15. The electronic device according to claim 14, characterized in that: The number of the ultrasonic sensors is plural.

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